This PDF file contains the front matter associated with SPIE Proceedings Volume 12507, including the Title Page, Copyright information, Table of Contents, and Conference Committee.

The optical window of space optical system is important for optical observation. It been used to isolate the extreme space environment and protect precision optical elements. There is no thermal design for optical windows on traditional space systems. However, under the space thermal alternation application environments, the temperature change can lead to deformation of optical elements which will cause image distortion. Especially for the large-aperture optical system. The study on thermal design for space optical window becomes very meaningful. In this paper, by the way of heat conduction and radiation, two available heating region (the window frame and the light baffle inner surface) are utilized to indirectly affect the temperature of space optical window. Three thermal design methods are presented, and the effects of different methods have been evaluated by the simulation study on a fictional LEO earth camera’s optical window. The results show that the thermal design of heating two available region can both reduce the window’s temperature difference and improve its optical performance. Especially, the effect of heating frame is more significant. This study can be used as a reference for the thermal design and thermal control strategy of large aperture space optical window in the future.

We propose a structure based on fiber-optic gyroscopes for gravity measurement in accordance with the tilt-coupling effect, where Sagnac effect can remove the coupling between translational and rotational motion in the tilt-coupling effect. A fiber-optic gyroscope with a sensitivity of 2 × 10⁻¹¹ rad/s²/√ HZ in sub-millihertz frequencies is reported, which can be utilized to measure the rotational motion in gravity measurement. The application of dual-polarization configuration improves the adaptability of exploration environment.

Composite joint plays a significant role in the composite sandwich structural connection. However, its complex structure and environmental conditions can lead to difficulties in real-time monitoring. Regarding this, a threedimensional finite element simulation model has been developed for the prediction, propagation and improvement of adhesion failure in an adhesively bonded laminated structure. In this study, a tensile fracture monitoring test under fiber Bragg grating-based monitoring was designed using the Fiber Bragg Grating (FBG) sensors. The simulation, based on the cohesive zone method with Hashin, Chang-Chang, Hou criteria and the mixed criteria, also indicates that debonding of the filler area was the main failure behavior of this composite joint. Using the finite element simulation model based on mixed criterion, the predicted initial and final failure loads have a good agreement with experiments, and the effects of the FBG sensors layout were investigated and discussed on Acquisition and processing of failure signals of composite joint. The findings in this work are helpful to improve mechanical behaviour of composite joint and improve the FBG monitoring to meet the high criteria of the aerospace industry.

With the advancement of science and technology, Power over fiber (PoF) technology is gaining more and more popularity. This paper presents a detailed study of the output characteristics of PoF technology for long distance transmission in OPGW cables.

Multi-damage detection for composite materials has been a hot issue in the field of structural health monitoring. In order to further study the problem by means of FBG sensors, an optical fiber sensing system has been built to enable the detection of delamination damage in composite laminates. The system includes sensing strain, data processing and damage localization algorithms. A model of a carbon fiber/epoxy laminate is created using the finite element analysis. The stress cloud chart of the laminate when subjected to a hammering load is calculated and analyzed and it is concluded that stress waves propagate along 45 degree direction of carbon fiber and stress is concentrated at the delamination and then decreased obviously. The Fourier transform and wavelet transform are used to analyse the key level signal of the wavelet transform and to determine the area of delamination damage, and the experiment is checked by ultrasonic C-scan. The experimental results show that by building a network of fibre Bragg gratings(FBG) sensing systems, the hammering test can detect multi-delamination damages of different sizes in composite laminates, the smallest of which is 10mm in diameter, providing a basis for subsequent composite structures health monitoring in complex environments.

Aiming at the problem that the optical cable is wrongly disconnected due to false identification in the maintenance of the power optical cable, we propose a scheme of multi-channel optical cables identification based on phase sensitive optical time-domain reflection technology. Electric optical cables identification system based φ-OTDR is experimentally demonstrated, with a monitoring channel number of 4 and SNR over 15dB.

In order to reduce the phase noise introduced by the unbalanced interferometer in the distributed feedback (DFB) fiber microphone modulation system, a phase noise compensation method based on a stable laser source as an optical reference is proposed. The narrow linewidth laser source is incident on the unbalanced Michelson interferometer shared by the microphone, so that it has the same optical path difference. This optical phase noise information is used to offset the noise introduced by the interferometer, so as to achieve the purpose of noise suppression. The principle of the unbalanced interferometer composition and suppression are theoretically analyzed and experimentally verified. The experimental results show that under the quiet conditions of the laboratory, compared with the structure that has not been suppressed, the noise of the microphone primitive is reduced from about ± 0.2rad to within ± 0.04rad, the power spectral density is reduced to less than -58.95dB/Hz^1/2. It can be suppressed by more than 32dB at the noise peak, and the suppression effect of the phase noise is very obvious.

Deep learning methods have been widely used to complete the task of stereo matching in recent years, which is the key step in machine vision measurement. State-of-the-art methods are three-dimensional (3D) end-to-end networks that forms a cost volume by concatenating extracted features and processes it with 3D modules. Despite the strong performance in terms of accuracy, 3D networks mostly have high computational cost, heavy memory storge and long run-time. In this paper proposed Local Cost Volume Refinement Network (LCRN), which is a two-dimensional (2D) end-to-end network composed of feature extraction, disparity initialization, disparity refinement and disparity mergence module. LCRN initializes disparity maps by using correlation layer and residual blocks, and refines them by using local cost volumes, residual blocks and disparity regression. Local cost volumes are constructed by warping right features and giving a small disparity shift. To verify the effectiveness of LCRN, the network was pre-trained on SceneFlow dataset and fine-tuned on ROBI dataset. The network is evaluated on the test set of ROBI for robotic bin-picking. Experimental results show that LCRN maintains a competitive accuracy while having fast run-time and requiring less memory storage.

We simulated a large-aperture capacitively coupled plasma (CCP) using a two-dimensional fluid model, and explored the effects of radio frequency, electrode power, and gas pressure on the period-averaged electron density and electron temperature. The influence and control ability of various discharge parameters on the plasma uniformity are analyzed, which provides reference for the selection of plasma process parameters.

We verify the relationship between strain response wavelength of strain sensor and force magnitude and force point in practical engineering measurement. Six strain sensors with wavelength intervals of 2 nm were cascaded in a single channel and fixed on the surface of a thermal pipeline with an inner diameter of 50 cm and an outer diameter of 58 cm covered with thermal insulation material. The spacing of the fixed points is 1 m, and the package angle is 30° , 60°, 90°, 330°, 300° , 270° respectively. By changing the position of the external force point and the size of the force, through the theoretical analysis of the mechanical model, good results are obtained. The amplitude of the wavelength response can feedback the magnitude and position of the corresponding force.

At present, there are many problems such as high cost and high pollution in fabrication methods of anti-reflective structures on silicon surfaces. To solve this problem, the utilization of nanosecond pulse infrared laser processing technology is proposed to realize the fabrication of anti-reflective structures on silicon surfaces. Compared with polished silicon, the reflectance of the silicon surface with the anti-reflective structure can be reduced by 89% in the visible light band. In order to unfold the anti-reflection mechanism of the black silicon substrate and optimize the structures, finite difference time domain (FDTD) is adopted to simulate the anti-reflective conical structure with tunable aspect ratios and generate the corresponding reflectance spectrums. To optimize the aspect ratio of silicon surface structure, the processing parameters of nanosecond pulse infrared laser are investigated, which not only realizes the morphology control of the surface structure but also optimizes the anti-reflective performance of the silicon surface. The result shows that the reflectance of the silicon surface is reduced to 3.87% in the visible light band by the anti-reflective structure fabricated by nanosecond pulse infrared laser processing. Also, the variation of aspect ratio of the structure could be monitored and predicted by acoustic signal detection technique. This detection technique provides potential applications in structural integrity monitoring during the fabrication process.

The system performance of many industrial products is dominated by the surface profile accuracy of their primary component, thus it is of great essence to achieve high precision profile characterization. The chromatic confocal technology provides an effective means for precise measurement of surface profile, yet there exists non-negligible errors when measuring transparent curved component. The aim of this paper is to investigate the effects of the curvature of component on the confocal rays and obtain its bilateral surface profile by chromatic confocal technology simultaneously. The assumption of tilted plate approximation for curved specimen was made. By adopting the optical ray tracing analysis, a modified model was then proposed to correct the measurement error existed in the traditional one. The validity of the proposed model is conducted by 2D bilateral profile measurements of the hemispherical shells after the calibration with tilted fused silica plates. Experimental results show that the proposed model significantly improves the measurement accuracy of bilateral profile of curved transparent components at large equivalent tilt angle. This method overcomes the drawbacks of other spatial coordinate based profile measurement methods, and achieves high accuracy simultaneous measurement of bilateral profile of transparent components.

To discover and understand the solidification characteristics of energetic materials in the melting and casting process, the distributed optical fiber based on back Rayleigh Scattering was embedded in TNT/Octogen-based melting and casting explosives to monitor the solidification process from the liquid phase, to finally achieve realtime online monitoring of the strain of melt-casting during curing. The method of implanting the strain sensing optical fiber is to fix the optical fiber at the position in contact with the mold according to a predetermined path, fix the temperature sensing optical fiber in the center of the mold from top to bottom, and record the change of the center wavelength Rayleigh Scattering during the curing process, then converted into a stress index. The solid-liquid phase transition interface identification method based on an optical fiber sensor and proposed here, allows direct determination without decoupling from the temperature field. Therefore, the method of implanted distributed optical fiber sensing can monitor the solidification process of molten-cast explosives, which provides an effective and reliable method for more detailed and comprehensive analysis and monitoring of the solidification characteristics of energetic materials.

Existing aspheric testing methods are sensitive to environmental effects. The digital moire interferometric technique (DMIT) demodulates surface errors from a single interferogram by building a virtual interferometer to avoid environmental effects. This method requires the actual carrier and the virtual carrier to be the same. In this paper, the effect of carrier deviation on DMIT is investigated. It was found that the carrier deviation would extend the spectrum of low-frequency information. Spectrum expansion can deteriorate the noise immunity of DMIT. Spectrum expansion may also lead to spectrum overlap. Method for determining the actual carrier from frequency domain is analyzed. A carrier alignment algorithm is proposed, and the simulation results deviate from the true value by only 6%.

A method to compensate for the dispersion-induced power fading in a radio-over-fiber (RoF) link is proposed and experimentally demonstrated based on stimulated Brillouin scattering (SBS). In the central office, a part of the optical carrier is used to generate frequency-definable two-tone pump light via carrier-suppressed double-sideband modulation. The two-tone pump light generates both Brillouin loss and gain spectra at the vicinity of the optical carrier when it counter-propagates with the signal light in a spool of single-mode fiber (SMF) located in the central office. Hence, the relative phase difference between the optical carrier and the ±1st -order modulation sidebands of the signal light can be freely varied by using the SBS-induced carrier phase shift, which can compensate for the power fading induced by the group-velocity dispersion in the transmission fiber between the central office and the base station. In the experiment, a flat gain in the frequency range of 10 MHz to 10 GHz is achieved for the signal transmission over 45-km SMF. The error vector magnitudes (EVMs) of the transmitted 64 QAM signals centered at 4.8 GHz and 5.0 GHz are greatly improved after dispersion-induced power fading compensation.

With the advent of the "Industry 4.0" era, the requirements for measurement efficiency, size and accuracy in the assembly process of large-scale equipment have been continuously improved. In the assembly process of large-scale equipment, due to the limitations and occlusions of components and assembly tooling, a single laser tracker cannot complete the measurement of all target points. Therefore, it is necessary to use multiple trackers to work together to build a measurement network covering the entire assembly space. In this paper, through the forensic-based investigation optimization algorithm, the three-dimensional coordinates of the stations of multiple laser trackers are used as the high-dimensional input parameters, the side of the bounding box of the large-scale measurement field is used as the feasible region of the high dimensional parameters, the ray accessibility of the laser tracker is used as the statistical result, the number of public transit points of adjacent stations of the laser tracker and the number of visible digital-analog key points are used as constraints, the ratio of the number of visible points of multiple laser trackers to the total number of points is used as the objective function, the optimization is carried out in the form of greedy iterative fitness function, and finally the maximum coverage rate under the measurement network is obtained in complex environments such as tooling occlusion. In a word, this method shortens the station layout time and the overall assembly period through autonomous calculation, and has certain practical significance for improving the assembly efficiency of large-scale equipment.

In this paper, a mirror with 400mm aperture is taken as the research object. A test system and experimental method for the study of the mechanism of action between the surface shape of the mirror and the actuating force are designed. The system is composed of five parts: optical element, the metering type surface shape control device, a stress-strain testing system, a measuring device for the mirror surface shape and a multi-dimensional translation table. Firstly, the support mode of φ400mm aperture plane mirror is determined by means of optically integrated analysis technique. Secondly, the design of the metrological surface shape control device is completed. The metrological surface shape control device can realize the micro-stress support of the mirror and provide the initial state for the experimental study. At the same time, the actuator component on the back can test and display the driving force in real time. Thirdly, with the mirror shape as the optimization target and the force applied on the back of the mirror as the control variable, the size of the force can be obtained by using the optic-mechanical integrated analysis technology for simulation optimization. In the experiment, the mirror shape can meet the expected requirements by applying the corresponding tension or pressure through the back actuator. In addition, set up a mirror surface shape - promoting the motivation mechanism research and testing system. The research flow of mirror shape regulation mechanism is put forward, through reflection mirror shape detection, the form data processing, and actuating force calculation, and the power, surface shape control effect assessment, through several rounds of iteration calculation and adjustment, realize the regulation and optimization of reflection mirror. The experimental system and method proposed in this paper provide a theoretical basis for the further study of active control technology of large aperture mirror.

It is known that the sensitivity of X-ray phase-contrast grating interferometry with regard to electron density variations present in the sample is related to the minimum detectable refraction angle. In this article an X-ray phase template is developed that allows for a realistic and quantitative determination of the sensitivity in X-ray phase-contrast imaging using cascaded grating interferometers. The template is designed as a periodic structure composed of different inclination angles and fabricated on a PMMA substrate. Fourier analysis of the moiré fringe patterns generated by the interferometer is used to obtain the phase-contrast image of the template. Experimental results show that the sensitivity, i.e. the minimum detectable refraction angle of this interferometer, is between 0.1 μrad and 0.2 μrad for the template with structure period of 4 mm. This work will help to evaluate and optimize existing cascaded grating interferometers for x-ray differential phase-contrast imaging.

Frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR) can transmit and receive high frequency signals, up to 10G~100GHz, and can achieve micron-level high precision measurement and three-dimensional imaging of objects. If the frequency sweep of FMCW LiDAR is linearized, it can be extracted by Fourier transform, but most existing lasers do not have ideal linearity. In this paper, an iterative learning method of frequency sweep compensation is used to improve the linearity of frequency sweep. The semiconductor laser is one of the core components in the control system to improve the linearity of frequency sweep. Its performance determines the signal frequency and measurement accuracy of FMCW LiDAR. In this paper, the vertical cavity surface emitting laser (VCSEL) as an example, the equivalent circuit model of VCSEL is established by rate equation. An experimental platform is built to simulate the equivalent circuit model of the parasitic network, calculate and analyze each parameter, and verify the accuracy of the parameters of the equivalent circuit model and the parameter extraction method.

At present, most polarization imaging techniques cannot recover objects with different polarization characteristics in the same field of view. In this work, the shortcoming is overcome by estimating the global varying Mueller matrix of the target. After that, the illumination light with globally varying polarization state is estimated to inhibit the noise caused by computational imaging. The descattering imaging experiments through turbid water indicate that the images recovered by our method present the similarity to the targets without scattering, and the noise is suppressed to some extent. In addition, the superiority of the proposed method is proved by comparing with other polarization underwater imaging strategies.

In order to achieve replication of the ultra-thin metal x-ray focusing mirrors with high accuracy and efficiency, which is the key component of the EP satellite independently developed and manufactured in China, the simulation and experimental research on the demolding process of the x-ray focusing mirrors are carried out in this paper. The temperature and stress fields of the entire mandrel (aluminum) and the shell (nickel) during cooling process is simulated by finite element analysis, and the evolution of the interface stress during the demolding process is analyzed. When the temperature of the mandrel and shell decreases from 45℃ to 10℃, the equivalent stress at the interface between the mandrel and the mirror reaches 5.5MPa, which is larger than the adhesion strength between Au film and mandrel. Due to the difference in material thermal expansion coefficient between the mandrel and the mirror, it can be used to release the x-ray focusing mirror shell from the mandrel by cooling according to the experimental validation. Furthermore, the shell could separate from the mandrel by means of high precision demolding automatic device. After demolding, the angular resolution of the mirror is 25.1 "HPD (Half Power Diameter) by the x-ray testing, which meets the requirements of the project. The reliability and advancement of the technology are verified.

With the rapid development of 5G/6G communication technology, people's requirements for transmission rate and delay experience are also increasing. The digitized radio-over-fiber (DRoF) technology greatly simplifies the front-end hardware due to the use of digital processing, which has aroused great interest in digital-centric systems or centralized networks. Aiming at the series of bottlenecks faced by traditional RoF systems in mobile fronthaul (MFH), such as high cost, high complexity and low spectral utilization, a delta-sigma-over-fiber (DSoF) transmission technology based on delta-sigma modulation is proposed, which can push digital signal processing into the transmission chain as soon as possible, and has strong competitiveness in MFH. Firstly, the modulation principle of delta-sigma is analyzed, and then the delta-sigma signal transmission system is designed. Finally, factors affecting the delta-sigma signal transmission performance are deeply studied through MATLAB simulation and experiment. The results show that this system can realize the digital transmission of orthogonal frequency division multiplexing (OFDM) signals, which can provide reference for the development of next-generation mobile communications.

As an important parameter to reflect the degree of disordered movement of granular system, granular temperature needs to be measured by speckle visibility spectroscopy (SVS). The traditional reflected SVS requires polarizers at the light source and detector to filter the reflected light from the surface and the large thickness of the particle is required. In this paper, a transmission speckle visibility spectroscopy method is proposed. Results show that the method can effectively improve the signal-to-noise ratio of speckle signal and reduce the complexity of measuring device. Moreover, it has great compatibility for the granular system with different thickness.

With the wide application of optical thin films, the requirements for the spectral transmission range and refractive index of thin film materials are getting higher and higher. In this paper, a new type of thin film material sintered from SiO₂ and Al₂O₃ is studied. The single-layer film was evaporated by electron beam evaporation, and its refractive index uniformity was measured by ellipsometer and its spectral transmission range was measured by spectrophotometer and Fourier spectrometer. Finally, a multi-layer high-reflection film is prepared by using the material, and the film has a high reflectivity and a flat and uniform surface.

Precision glass molding (PGM) technology is one of the best methods for processing optical glass lenses, but the incomplete filling in the PGM process has a negative impact on the accuracy of the fabricated aspherical glass microlenses (AGM). It is found that the main reason for this phenomenon is trapped gas between the mold and the glass preform during PGM process. This study observed the gas trapping morphology of the prepared AGM, theoretically analyzed and numerically simulated the formation of trapped gas, and developed the method of eliminating trapped gas induced filling defects. Specifically, in the molding process, the gas trapped in the molding chamber is difficult to be released. We proposed to lower the temperature of the glass and mold to make the softened glass return to the glass state, so that the gas can flow between the two surfaces to achieve the purpose of releasing the trapped gas. When the pressure gas is released, a second molding can effectively improve the filling effect. We call this process cooled down molding (CDM). Experimental results prove that CDM can effectively improve the filling rate in a short period of time and filling defects can be effectively eliminated by designing CDM molding process.

With the continuous development of advanced optical manufacturing method, ultra-precision optical components are widely used in aerospace, microelectronic equipment, optical precision measurement and other major application fields. Surface defect is one of the key parameters of ultra-precision optical components. It can be challenging to the surface defect measurement method of ultra-precision curved optical components. Optical micro-imaging measurement method is an effective defect measurement device. Illumination system optimization is one of the key technologies. This paper mainly provided the experimental results of the surface defect measurement of typical curved optical components with microscopic imaging, analyzed the influence of different light source types, different illumination angles, different illumination brightness and other parameters on the imaging effect of curved surface defects, and the comparative experiments of various types of curved optical components were carried out. The experimental results were analyzed and discussed from the aspects of image contrast, light uniformity, and capacity of weak defect measurement. The results of the paper can provide a certain reference for the optimization and improvement of the surface defect measurement method of ultra-precision curved optical components.

A coherent dual-band microwave photonic (MWP) radar system is proposed and experimentally demonstrated in this paper. In the transmitter, coherent dual band linear frequency modulation (LFM) waves with the characteristics of tunable central frequency and the same large bandwidth are generated based on an improved optical frequency operation module (OFOM). In the receiver, the information of targets is obtained after the echoes at two bands are received and de-chirp processed simultaneously. Experimentally, the presented coherent dual-band MWP radar system operating in X band and Ku band with an instantaneous bandwidth of 3GHz is constructed. A target-detection experiment verifies that centimeter level resolution can be achieved by the system.

Circularly polarized light is widely used in wireless communications, polarized imaging and circular dichroism spectroscopy. The existing miniature circular polarization detection structure cannot guarantee high transmission efficiency and extinction ratio at the same time. In this paper, we propose a terahertz circularly polarized detection metasurface based on dielectric materials. The proposed structure can well distinguish the handedness of circularly polarized light. At 2.3Thz, the transmission efficiency is greater than 95% and the extinction ratio is greater than 250dB. I believe our design could facilitate the development of devices such as small biomedical imaging.

Based on the theory of reflection and rotation for vector, this paper theoretically analyzes the scanning scheme by rotating the coaxial two-mirror, and constructs the transformation matrix for vector. On this basis, the relationship between the five control parameters for the scanning scheme by rotating coaxial two-mirror and the scanning trajectory (corresponding to different scanning strategies) is deeply analyzed. The scanning scheme by rotating the coaxial two-mirror designed and analyzed in this paper has the advantages of simple control (with uniform circular motion), high scanning efficiency (100%), and flexible scanning strategy and so on. It can realize the functions of rapid scanning for imaging, region ergodic searching, random or complex path for scanning and so on.

Off-axis aspherical surface have the advantages of excellent optical performance and simplified system structure. In order to satisfy the requirements of high-precision off-axis aspheric mirror in the telescopic system of some equipment, the research on ultra-precision manufacturing technology of off-axis aspheric mirror is carried out, and a composite polishing and detection technology based on robot-controlled optical surfacing and ion beam figuring is proposed. In the processing stage, the robotic flexible polishing and gadget polishing are used to quickly grind and polish the aspheric surface, and then the pitch lap is used to smooth the mid-spatial-frequency errors. Finally the aspheric surface is machined to the final requirement by ion beam figuring. In the detection stage, the coordinate measuring machine is used to detect the surface shape in the grinding stage, and the stigmatic null test is used to detect the aspheric shape in the fine polishing stage. Using the proposed method, the off-axis aspheric surface of a caliber 408mm is machined and tested, and the final surface figure error was 0.015 λ (λ = 632.8nm), which meets the requirements of the index.

Photo-thermo-refractive (PTR) glasses exhibit promising characteristics for volume Bragg grating fabrication, one of key devices for construction of high performance lasers, among other optical device and systems. Aiming at employing this type of glass materials in the field of integrated photonics, buried optical channel waveguide is manufactured in PTR glass substrate by Ag⁺/Na⁺ thermal ion exchange and subsequent field assisted ion migration. The Ag⁺ doped zone in glass substrate, which is also the waveguide core, can be driven to several micrometers under the glass substrate surface, which decreases the propagation loss to a value as low as 0.12dB/cm, by eliminate scattering loss at glass substrate defects. Cross section of the waveguide core can be also engineered to match the core of single mode fiber, ensures a low coupling loss to single mode fiber. Analysis demonstrated that the buried optical waveguide fabrication proves can be expected to be applied in functional integrated optical device implementation.

The improvement of surface shape accuracy and surface quality is an important aspect of ultra-precision grinding. In this paper, experiments were carried out by using a four-axis ultra-precision grinder to analyze the influence mechanism of grating machining and polar axis machining on surface shape accuracy and surface quality, and to clarify the advantages and disadvantages of the two machining processes. In the process of polar axis machining, the influence of polishing on the surface shape accuracy is analyzed, and the influence of different feed modes and x direction offset on the surface shape accuracy is clarified. By establishing the influence model of the error source on the surface shape accuracy, the error factors of the tool alignment were analyzed emphatically. Through numerical calculation and analysis of the specific form of tool alignment error, a reasonable grinding wheel center alignment scheme was put forward. The wear law of grinding wheel was analyzed through process test, and a reasonable dressing method of grinding wheel was put forward.

Transient structural information of matter can be obtained by time-resolved X-ray measurement, such as ultrafast X-ray diffraction (UXRD) and ultrafast X-ray absorption Spectroscopy (UXAS). A time-resolved ultrafast X-ray source is necessary for ultrafast X-ray spectroscopy measurements, such as XFEL or synchrotron radiation source. Because of the high cost of X-ray free electron laser (XFEL) and synchrotron radiation source, we designed a laboratory ultrafast plasma X-ray source driven by 800Hz high-energy laser. The X-ray pulse duration is shorter than 100fs. Copper was chosen as the target material of the source, and the expected photon flux can reach 10⁷ photons/s. The target material can also be replaced by other common target materials.

With the continuous development of the technology and informatization, the current research and application of the technology of the digital twin has become a hot spot. The technology of the digital twin is applied to the optical-mechanical system design, the optical-mechanical manufacturing, the optical-mechanical installation and calibration, as well as the inspection over the whole process and the whole life cycle. The objective of this paper is to study the construction of the digital twin in the crucial links of the installation and calibration process over the whole process of the optical-mechanical system, as well as the modeling and simulation of the digital twin in the optical-mechanical installation and calibration process, including the ideal model simulation, the optical-mechanical part-level simulation, the optical-mechanical thermal coupling simulation, the total integration simulation, as well as the prediction of the use effect of the optical-mechanical system. In the past, the ex post data were collected in order to feed back for the model design and the process, so as to improve the accuracy of the simulation. Accordingly, the actual measured data of the optical-mechanical part entity are substituted into the model. Moreover, the results of the simulation integration are used to correct the technical scheme of the process. Furthermore, the physical entity data generated during the execution of the correction scheme are transmitted to the simulation model once again, so as to achieve the dynamic data interactive application of the optical-mechanical system in the physical entity and the virtual model. Thus, the dynamic system is formed. In the end, the data exchange, sharing as well as the mutual mapping between the physical entity and the virtual entity during the installation and calibration of the optical-mechanical system can be realized. In conclusion, the provision of the real-time data, the analysis and optimization of the installation and calibration process, as well as the decision making of the implementation plan in the aspect of the installation and calibration application of the optical-mechanical system, which provide an effective way for the process design of the installation and calibration of the optical-mechanical system as well as the digital improvement of the installation and calibration technology.

An image-rejection multi-band frequency down-conversion scheme is proposed and demonstrated based on photonic sampling. In this scheme, two radio-frequency (RF) signal replicas with a quadrature phase difference are sampled by two ultra-short optical pulse trains in orthometric polarization via the linear electro-optic modulation in a dual-polarization dual-drive Mach-Zehnder modulator (DP-DDMZM). After being polarization demultiplexed, the two sampled optical pulses are separated from each other and detected by using two photodetectors (PDs), respectively. Hence, the RF signals in multiple frequency bands are simultaneously down-converted to the intermediate-frequency (IF) band. Finally, the two IF signals are combined by using an electrical 90° hybrid coupler to eliminate the image-frequency components. In the experiment, an ultra-short optical pulse train with a repetition frequency of 8 GHz is generated by employing an electrooptic modulation-based time lens with the chirp compensation, and is used to achieve photonic sampling. The experimental results indicate that image-rejection down-conversion is achieved for the input signal in the frequency range of 6 GHz to 27 GHz, where the image rejection ratio is larger than 58 dB.

In order to solve the problems of complexity and inefficiency in traditional processing modes of aspherical optical components, the paper designs a compound machine tool based on the gantry structure and capable of double-sided machining. The tool spindles on both sides can be modularly replaced according to the selected combination process, thus guarantee a certain degree of flexibility in processing. Firstly, the structure of the machine tool is designed and 3D modeled. After that, the stiffness models of the classical joints are analyzed, and the finite element analysis of the whole machine is carried out based on the virtual structure method. On the basis of structural design and simulation analysis, the mathematical model of the beam optimization problem is established, and the lightweight design of the beam is carried out by using the adaptive multi-objective method. The simulation results show that the design and analysis of the multi-axis optical compound machining machine tool is reasonable and effective.

A non-mechanical photoelectric tracking technology based on liquid crystal phased array was proposed. A mathematical model of a liquid crystal phased array photoelectric tracking closed-loop system was established. The laser emits incident light of a specified wavelength. Incident light enters the liquid crystal phased array through polarizers, waveplates and other optical devices. The difference between the deflected beam and the incident light is received with the camera after the liquid crystal phased array. The liquid crystal phased array adopts voltage control to achieve the deflection of the incident beam and achieve the purpose of accurate tracking. The motion state of the simulated target is analyzed and a modern control algorithm is designed. Subsequent simulations and experiments were conducted. Simulation results show that the dynamic tracking error of the liquid crystal photoelectric tracking system is better than 18μrad. Its closed-loop bandwidth exceeds 2.3HZ. On the basis of the above work, a desktop demonstration experiment platform was built. Experimental results show that the dynamic tracking error of the liquid crystal tracking control system is better than 20μrad, which has good robustness.

KDP (potassium dihydrogen phosphate) is often chosen as a frequency doubling component for lasers because of its strong nonlinear optical properties and its possession of a high laser damage threshold. However, due to its inherent physical properties, KDP crystals are not easy to machine. In this paper, we try to polish KDP using fixed abrasive polishing technique. Copper oxide, carbon powder and phenolic resin are selected for the preparation of pellets for polishing. Orthogonal tests on the workpiece without destroying the KDP and the best process parameters were decided for the lowest roughness. The thermodynamic simulation is also used to analyze the heat of the polishing process to ensure that no thermal damage occurs to the workpiece during the machining process.

Facing the urgent needs of piano teaching informatization construction in the post-epidemic era, a research on optical teaching instrument suitable for remote online guidance on piano practice is carried out. According to the teacher’s active correction on students’ hand shape and fingering in the process of piano teaching, an optical instrument design method for projection and imaging integrated light path design is proposed to meet needs of the online visual analysis and optical guidance of the teacher in the process of individual piano fingering exercises which is usually carried out offline. By adopting the spherical off-axis four-inverted optical structure, the teaching instrument realizes the compact design of the large field of view and wide spectrum optical system, and the optical system envelope is only 110mm×35m m×30mm. The design results show that the teaching instrument can realize the projection and imaging of the surface within the range of 1240mm of line length at a height of 500mm from the keyboard (the top of the piano score bracket), which can fully cover the imaging requirements of the whole piano keyboard (1200mm); The imaging spectrum of the optical system covers 450nm to about 900nm, and the MTF of the full field of view reaches 0.6 (@33lp/mm) or more, which can fully meet the requirements of the digital and symbolic optical projection of any piano key as well as the clear imaging of the fingers, and thus realizes the effect of offline teaching in the process of online piano teaching.

UlE, as a kind of ultra-low thermal expansion glass, has been widely applied in large-aperture optical mirrors and space telescopes. However, hard-brittle material feature of ULE brings certain difficulty for machining. In this paper, rotary ultrasonic vibration-assisted peripheral grinding (RUPG), combining rotary ultrasonic vibratio (UV) and conventional grinding (CG) is proposed, and grinding process and quality characteristic are investigated in terms of surface morphology, grinding force, surface roughness, subsurface damage depth, and subsurface morphology. A serious of comparative experiments for between RUPG and CG were conducted. The results show that rotary UV in RUPG can markedly decrease the grinding force with a factor of 46.78%. The change rule of grinding force with the varying of grinding parameters in RUPG is consistent with that in CG, i.e., grinding force increases as the increasing of grinding depth and feed rate, while it decreases with the growth of spindle speed. Grinding surface marks were found to be obviously weakened by UV and surface consistency was accordingly improved. Besides, measurement results of surface roughness also real that UV plays a positive role in diminishing surface roughness by almost 23.01%, and reducing the subsurface damage depth by a factor of 17.19%.

Single crystal germanium, which is a typical infrared optical crystal used for aerospace and astronomy applications due to their excellent mechanical, optical, and chemical property is difficult to obtain super smooth surface in ultra-precision turning and easy to cause tool wear owing to its inherent brittleness and hardness. In the processing process of single crystal germanium optical elements, good surface roughness is beneficial to improve the diffraction efficiency of single crystal germanium, while small cutting force can effectively lower the diamond tool wear caused by high hardness of germanium. In this paper, the single variable method is used to study the influence of the main factors in the single point diamond turning process on the surface roughness and cutting force of single crystal germanium, including spindle speed back cutting depth and feed. The experimental results are used to guide the machining process of the single crystal germanium diffraction surface, and the appropriate process parameters are selected to perform ultra-precision turning on the single crystal germanium with a very small cutting force to obtain a sub-nanometer ultra-smooth surface to improve the diffraction efficiency and reducing tool wear.

Gas ionization chambers were the first detector devices used for radiation detection, and they are widely used in the field of non-destructive testing because of their long service life and reliability. The time response characteristic is an important performance parameter of gas ionization chamber detectors, which has been studied for many years through experimental tests and simulations. In gas ionization chambers operating in the cumulative mode, the response time of the detector is determined by the drift rate of the ions. The existing parallel plate ionization chambers have low electric field strength in some areas, which prolongs the response time of the gas detector. In this paper, a detector with a fast response time is proposed and a variety of simulation tools are used to simulate the ionization chamber. A glass plate ionization chamber model was built using SolidWorks, and the detector inter-pole electric field distribution and detector output signal were simulated using the finite element analysis software MagNet and Garfield++. The results show that the interpolar electric field strength of the new electrode structure reaches 7.4 x 10⁵V/m, which is 48% higher than that of the parallel plate ionization chamber, and the response time of the glass plate detector is reduced to 0.15 to about 0.44 ms. Therefore, the development of the new electrode structure can effectively reduce the response time of the detector, which is important for the development and application of high-performance gas ionization chamber detectors. It is of great significance to promote the development and application of high-performance gas ionization chamber detectors.

In order to quickly obtain the optimal bonding styles in the adhesive bonded mirror, the simulation and experimental study of the adhesive bonding assembly process for plane mirror were carried out. A single-factor experiment was designed to study the variation of the PV and RMS values of the surface-shape of optical plane mirror with the change of various factors. Then, an orthogonal experiment was designed to study the optimal parameters for the optimal bonding process by taking the PV and RMS of the surface-shape as comprehensive indexes. A finite element model named "Mirror-Adhesive -Frame" was developed using ANSYS Parametric Design Language (APDL) to calculate the PV and RMS values of the surface-shape of the mirror after bonding. In addition, a interference instrument named ZYGO is used to verify the correctness of the surface shape from simulation. The results show that the prediction results of the developed simulation model are in good agreement with the measurement results. The values of surface shape index PV and RMS increase with the increase of adhesive layer diameter and thickness, and gradually decrease with the increase of adhesive layer position in R direction and H direction. The orthogonal experiment with four factors and three levels revealed that the diameter of adhesive layer is the main factor to change the shape of the surface. The optimal process parameters are as follows: adhesive layer diameter of Φ4mm, adhesive layer thickness of 0.1 mm. adhesive layer position in R-direction of 40 mm and adhesive layer position in H-direction of 9.5mm.

Microwave photonic mixer owns the advantages of wide frequency coverage range and large processing bandwidth. However, the LO spurious of the mixer is still high, which severely limits its application where the LO spurious locate at the band of interest. In this paper, a novel microwave photonic mixer with complete suppression of LO spurious is proposed. A dual-drive mach-zehnder modulator (DD-MZM) is adopted. The LO signal and RF signal are applied to the DD-MZM through the two driven ports. The optical signal is controlled to make the LO signal to be the phase modulation and the IF signal to be the intensity modulated. Finally, after the intensity detection completed by the photodetector, only the IF signal will be preserved and the LO spurious can be all suppressed. A proof-of-concept experiment is performed. Experimental result shows that 50-dB suppression of LO spurious can be realized.

Photovoltaic cells are an important component of a PoF system and their conversion performance is critical to the efficiency of the PoF system. The experimental results prove that EPCV enhances the reliability and overall efficiency of PoF technology and therefore drives the development of PoF technology in power systems and public safety.

In order to better utilize the broadband advantage of microwave photonic radar, a signal transmission model is proposed to analyze the transmission of electric signal and optical signal on microwave photonic link. In this model, signal transmission is divided into three processes: electro-optical conversion, optical signal process, and optical-electrical conversion. For each process, the connection of devices is established by the radar design, and the input output relationship of each device is modeled by the parameters. And for each device, its effect on the performance of the microwave photonic link can be calculated by its parameters. Therefore, this signal transmission model is able to help researchers to design and analyze the microwave photonic radar. Proven by the experimental results, this signal transmission model can explain the important phenomena of the microwave photonic link, and can effectively analyze the influence of each device on performance of microwave photonic link.

Coaxial transmission optical systems can be assembled by optical centering processing and optical centering assembly to eliminate the eccentricity and tilt of each lens, thus ensuring the coaxiality of the lens. Non-coaxial transmission optical systems cannot be assembled by the traditional optical centering method, and this type of system poses a new challenge to the assembly method. Aiming at a non-coaxial transmissive optical system, this paper proposes a precise assembly method based on the spatial coordinate change and the principle of self-collimation imaging. Firstly, we calculate the spatial angle and eccentricity value of different axis mirror groups, and then use two self-collimating theodolites and optical reticle centering tools to construct the spatial angle reference and eccentricity reference for different axis mirror groups. Then, the spatial position of each lens group is determined by the adjustment method of auto-collimation. The article finally carried out the alignment experiment. The wavefront RMS of the optical system after alignment is 0.026λ@632.8nm which meets the design requirements and verifies the effectiveness of the proposed method.

In order to realize the real-time on-line monitoring of motor rotor temperature, a Fiber Bragg Grating (FBG) temperature sensing system using fiber optic rotary joint to transmit signals was built. The effects of the acceleration of the rotor and the mounting angle of the sensors chain on the central wavelength of the FBG were studied. The temperature measurement test of a rotating shaft was carried out. The following conclusions can be drawn. The central wavelength variation of the FBG is related to the linear acceleration of the rotor surface, the density and thickness of the grating coating. For the rotor whose surface linear acceleration is within 100m/s 2 , when the thickness of the coating is within 100μm, the effect of acceleration on the center wavelength of the polyimide-coated or gold-coated FBG can be ignored. For the motors with higher linear acceleration, in order to prevent the impact on the temperature measurement accuracy, the angle between the FBG sensors chain and the rotating shaft is preferably controlled within 20°. For the motors with lower linear acceleration, the installation angle can be compromised according to the rotor surface structure. The experiment shows that the FBG temperature measurement system can run stably and measure the temperature change accurately during the variable speed process of the rotor. Compared with other rotor temperature measurement systems, the FBG temperature measurement system has a simple composition, and the sensors chain is light and small. It is a very promising rotor temperature monitoring system.

The axial compact fixing position of the optical element is mainly carried out in the form of tightening the compression ring in the optical lens assembly process. Most of the existing compression ring tightening methods use forceps and other general press ring tightening tools, the degree of tightening of the pressure ring when used mainly depends on the experience and feel of the assembler, cannot quantify the compression ring tightening torque. In order to solve the above technical problems, the research topic of optical lens compression moment quantification process technology is proposed. Based on the principle of strain sensor, a special digital explicit compression moment device was successfully developed. According to the mass production project of XX optical lenses, the test scheme of the tightening moment of each lens press is designed, and multiple compression ring tightening tests are carried out using a special digital explicit compression moment device, and the corresponding change relationship between the compression moment range of the whole lens and the lens surface type (RMS) is summarized. According to GB/T 34516-2017 "Spacecraft Vibration Test Method", the random vibration test method in the vertical direction of "sweep-vibration-sweep frequency" was used to complete the compression moment tightening performance and reliability verification. The test results are shown that the characteristic sweep curve of the optical lens before and after the vibration has not changed, the modality has always remained stable, the lens shape (RMS) remains unchanged, the optical lens is not loosened, the digital explicit compression moment device developed meets the technical requirements of the optical lens assembly process, and the compression ring tightening torque is quantified, which further improves the assembly quality reliability and assembly efficiency.

Compared with the traditional electronic reconnaissance receiver, the electronic reconnaissance receiving system using optical frequency comb down-conversion technology can simultaneously down-convert all the electromagnetic signals from the wide-band range (1MHz-20GHz) to the first repetition frequency interval range(DC-110MHz) for reception and measurement. This method can significantly improve the measuring speed and reduce the receiving cost. However, when the captured signal is a type with bandwidth like radar signal, the down-conversion spectrum may be aliased, resulting in the change of signal spectrum shape, which will affect the modulation type identification and frequency recovery of the signal. In order to solve the problem of modulation type identification of radar signals with spectrum aliasing after optical down-conversion, a modulation type identification method based on radar signal auto-correlation feature extraction is proposed in this paper. According to the characteristic that the auto-correlation function is insensitive to the spectrum aliasing after optical down-conversion, this method extracts the type identification features of auto-correlation envelope and its spectrum, such as skewness, kurtosis, impact factor, and finally uses SVM to identification the modulation type. Simulation results show that this identification method can accurately identify the modulation type of radar signal with spectrum aliasing after optical down-conversion, and has good anti-noise performance. When the SNR is higher than -3dB, the identification accuracy of this method for LFM and SIN after optical down-conversion is higher than 99%. For NP, BPSK, QPSK, BFSK, LFM and SIN signals with dynamic SNR between -6db and 10dB , the identification accuracy is more than 95%.

A robust algorithm is proposed for real-time abnormal behavior recognition in dynamic challenge including illumination change and pose variations. To cope with these factors, we present a new method through segmented sampling processing evenly divides the original video into several fragments and according to a certain sampling density, the description of one I frame and the description information of several P frames are obtained from each video clip. Through the Res2Net18 network, a behavior classifier based on the cumulative motion vector of P frames and a behavior classifier based on the cumulative residuals of P frames are built. The various frame information extracted from each video clip is entered into the corresponding network, and each network outputs a classification score. According to the type of frame information entered, the classification score based on each type of input in all video clips is summed and averaged, and the classification score based on each type of input is obtained at the original video level. The ensemble is carried out by means of weighted summation, and the total classification score is obtained as the output of the abnormal behavior recognition network. Experimental results on benchmark datasets demonstrate that the proposed method performs robustly and favorably.

The beamline optical system in the fourth generation synchrotron radiation light source and free-electron laser facilities puts forward harsh requirements on the performance of optical components, among which, the bimorph mirror is an adaptive optical component designed to meet the ultra-high surface shape progress regulation of the component and the wavefront compensation of the beamline. Domestic design and processing of bimorph mirror technology is still in urgent need of technical breakthroughs. To address this issue, we have studied the fabrication process of bimorph mirror, analyzed the design of the brake unit size in the bimorph mirror and the influence of the mirror clamp support method on the deformation process.

Reaction-bonded silicon carbide (RB-SiC) is a typically hard and brittle material that is prone to a large number of machining defects in conventional processing. In this study, laser in-situ assisted diamond cutting (In-situ LAC) technique was proposed to reduce the machining defects of RB-SiC in order to achieve a mirror machined surface. Firstly, a nano-indentation study of SiC, Si phase and position at the phase boundary under a constant load of 100 mN and 300 mN was carried out. The measured hardness value data and the indentation morphology observed by scanning electron microscopy (SEM) were used to investigate the weak position of RB-SiC and analyze the causes of the defects deeply. Then In-situ LAC and ordinary cutting (OC) of RB-SiC experiments were carried out to compare the machined surface quality. The SEM analysis of the machined surface features was also used to point out the suppression effect of the machined surface defects by the laser. It was found that brittle fractures on the surface of SiC particles were suppressed, leading to a significant increase in the ductile processing regions of SiC and Si. To further investigate the effect and mechanism of laser on the suppression of subsurface defects in processing. The surface was cut by focused ion beam (FIB) and the cross-sectional morphology was observed in-situ. The extension of subsurface cracks and fracture defects were further analyzed to explore the defect suppression mechanism more comprehensively.

Large container radiation imaging systems have a wide range of applications and play an important role in national defense and security inspection areas. In recent years, the development of detectors with photon counting capability will help to improve the detection performance of inspection systems. With individual pulses as the output, the photon-counting system carries energy and time information of radiating particles. The no-load count rate is high in large container radiation imaging systems and the pulse width is narrow under the standard of more than 90% no-pileup rate. Therefore, high-speed voltage comparators are more suitable for obtaining energy information. The chosen time interval to recognize crosstalk signals is 5 to 10ns, which can be achieved by most of the main control chips in data processing systems. The Steel Penetration model is simulated, and the results show that energy and time information have different optimal application conditions, but both can improve the performance of large container radiation imaging systems.

In this paper, based on the Laplace deformation technique of differential coordinates, a surface deformation technique of large-scale complex components based on optimal control points is proposed. Firstly, according to the structural characteristics and constraint conditions of the members, the force and deformation trend of the model are analyzed. The force on the curved surface is simplified into a simply supported beam section for force analysis. The deflection curve trend of the members under different constraint conditions is qualitatively analyzed. The control points are arranged at the maximum deformation to ensure the consistency of the maximum shape variables; Secondly, the arrangement of control points of components is optimized according to the deflection curve, and the points are collected in proportion along the direction of the deflection curve at a certain distance. After multiple deformation superimposition, the spacing and position distribution of control points are continuously optimized; Then, based on the centroid, the mapping relationship between the control points of the source model and the control points measured after deformation is established, and the corresponding positions of the corresponding points on the original model and the deformed model are determined; Finally, the Laplace deformation of the surface is carried out through experiments to realize the surface reconstruction. The results show that the accuracy of surface reconstruction can be controlled within 0.15mm, which overcomes the limitation of traditional large-scale deformation, greatly shortens the time and improves the actual operation level.

Hemispherical resonator gyro is a novel type of high-precision and high reliability inertial grade solid gyro. In addition to have the features of simple structure, reduction in the number of parts, small volume, light-weight, stable performance, strong anti-interference ability, no need of temperature compensation, which makes it widely used in inertial system. The hemispherical resonator is the core component of high-precision hemispherical resonator gyro. The effect factors affecting the precision of hemispherical resonator gyro are roundness, concentricity, roughness, quality factor (Q factor) and frequency splitting after the hemispherical resonator is machined. The processing method and strictly process control determine the precision and Q factor of the hemispherical resonator. The loss of hemispherical resonator is discussed. The mechanical loss factors of hemispherical resonator include surface loss, thermal elastic loss, anchor loss and internal friction loss. The limiting factors of hemispherical resonator Q factor are surface quality, processing stress and geometrical structure. The structure of hemispherical resonator is designed using Corning 7979 fused silica as material. The designed surface roughness should be less than 0.02μm, the roundness and concentricity should be less than 0.3μm. Comprehensively considering theoretical precision and engineering application, we proposed a set of precision machining technology, including precision machining, precision polishing, and chemical etching. Using such technology, the roundness of resonator sphere is 0.17μm, the surface roughness of resonator sphere is 15.2nm, Q factor is 3.11× 10⁷ .

In order to enhance wireless communication system’s robustness against interferences, a method of multi-channel backup transmission based on microwave photonics is proposed. It utilizes a spectrum replicating structure composed of optical frequency comb and other optoelectronic devices. The transmitter replicates the spectrum of signal to be sent onto multiple different channels and sends them simultaneously. The receiver carries out spectrum replicating with a certain overlap, which down-converts different channels’ receiving signals to the same band, so that they can be extracted by the same designed filters and then demodulated separately. In this way, multi-channel backup transmission for the same information is achieved. A five-channel backup transmission system is simulated as an example. Simulation results show that when parts of channels are interfered, the communication system can still work well using the other non-interference channels. This method provides a candidate for exploring new wireless communication anti-interference technique regimes.

In order to fulfill the traffic localization, the network coding (NC) paradigm is a promising approach that can significantly improve the throughput, end-to-end (E2E) delay, and energy efficiency for passive optical network (PON). On the other hand, more recently, the hierarchical modulation (HM) incorporates with advanced digital signal processing (DSP) technology can optimize the total available capacity of PON. In this paper, in order to optimize the network performance, we propose a joint physical layer NC (PLNC) and HM in PON. Subsequently, we evaluate the bit error rate (BER) of MQAM modulated PLNC that uses the proposed mapping scheme. Afterwards, as an application, a rate adaptation scheme for the method of PLNC is proposed. Simulation results show that combined HM and PLNC mechanism has better BER in OFDM-PON than the conventional NC. Meanwhile, the rate-adaptive PLNC is advantageous in various scenarios.

This paper primarily focuses on power-domain multiplexing in downstream intensity-modulation direct-detection (IMDD) and vestigial side band (VSB) based orthogonal frequency division multiple passive optical network (OFDM-PON). At the transmitter, according to the data’s importance, we utilize superposition coding (SC) by power controlling method which separates data into hierarchical layers and transmits the layers of data in the same frame adaptively. At the receiver, we propose successive interference cancellation (SIC) and subcarrier-to-subcarrier intermixing interference (SSII) mitigation. The simulation results show that the proposed power-domain for OFDM-PON system namely PD-OFDM-PON achieves a set of significant desirable bit error rate (BER) performance when we consider the different power allocation ratio depending on the signal to noise ratio (SNR) in this paper.

To mitigate the accumulated linearity chromatic dispersion (CD), this paper numerically analyzes the transmission performance of the Nyquist-pulse-shaped 16-quadrature amplitude modulation (Nyquist-16QAM) subcarrier modulation (SCM) in intensity modulation direct detection (IM/DD) using different digital equalizations. We first theoretically study the tolerance penalties performance of IM/DD system. Then we compare the CD sensitivity between multi-modulus modulus algorithm (MMA), modified MMA (MMMA), parallel MMA blind adaptation equalization, OFDE equalization based on training sequence and vestigial side band optical domain equalizer. It is shown that blind channel estimation achieves low-cost short-distance transmission, up to 30 km, while OFDE outperforms the blind adaptation compensation capability and provide up to 45 km transmission in terms of system BER at the forward error correction (FEC) threshold. In addition, the vestigialside band (VSB) filter is necessary in Nyquist-16QAM after transmission over 60km standard single mode fiber (SSMF). The receiver sensitivity is improved by 2.4dB at BER of 3.8×10^-3 for the 60km and 80km transmission under the VSB combining the OFDE.

An improvement project of LAMOST will be implemented soon. To improve the observation accuracy and spectral acquisition rate, a new integrated fiber positioner was designed for the new robotic Focal Plane System. This paper designs the drive system for the integrated fiber positioner, and introduces the mechanical, electronic and software design in detail. We also built a vision measurement platform with a telecentric lenses to test the position performance. The fiber positioner positions the fiber to target by first blind positioning and multiple position corrections. After the positioner completes the first blind move, the camera takes the fiber image and calculates the offset between the actual position of the fiber from its target position. Then, the drive system controls the fiber positioner move according the offset value to correct the fiber position. We achieve the final accuracy through iterative position corrections. Experimental results show that both the drive system and the fiber positioner have reliable performance and high efficiency. With a first blind move inside of its workspace, the positioner can position the fibers with a planar precision better than 100um, the position error is less than 10um after the second correction and the RMS error is less than 3um.

The multispectral high-resolution imaging system is composed of four wide-spectrum cameras, which can detect targets in the visible, short-wave infrared, medium-wave infrared and long-wave infrared spectrum simultaneously. In order to reduce the size of the system, the four wide-spectrum cameras use the same telescope. To achieve operating wavelengths covering four wavebands, the telescope uses a fully reflective design with a coaxial aspherical surface with a hole in the center of the primary mirror. If aberration-free testing is used, the central aperture will occur, resulting in incomplete aperture of surface shape detection. Thus, in this paper, a compensator is designed which can achieve the whole aperture of surface testing without centralized obscuration. At the same time, the impact of the misalignment of compensator in the optical path during the test is analyzed. The optical testing path adopts infinite conjugate working distance to reduce one adjustment amount of compensator. And the first surface of compensator is coordinated with the interferometer to adjust the angle of compensator quickly and accurately, which further reduces the measurement error introduced by the optical testing path. The design of the compensator can realize the control of sensitive misalignment, reduce the surface measuring error caused by the compensator misalignments, and eventually reduce the precise processing error.

Quartz material, as an important material, is widely used in aerospace, micro-optics, microelectronics and other fields due to its high hardness and good thermal stability. With the rapid development of science and technology, the demand for the machining accuracy and machining size of quartz material is increasing. However, due to the brittleness and hardness of quartz material, the traditional machining methods have problems such as edge collapse, high roughness, and difficulty in machining small size. Femtosecond laser direct writing technology, with its super high machining accuracy, can focus on the interior of transparent material or focus on the back surface of material through transparent material to remove the material. It has become the most widely studied micromachining method in China and abroad. In this paper, we studied the different medium assisted femtosecond laser treatment of quartz, the results show that the liquid environment can effectively reduce the surface roughness of laser treatment.

With the rapid development of microwave photonic technology in recent years, microwave photonic radar can generate and process signals far beyond the relative bandwidth of traditional radar, and can achieve centimeter-level resolution when imaging. However, the echo characteristics of microwave photonic radar are quite different from those of traditional radar, which degrades the performance of traditional imaging algorithms. Therefore, it is crucial to propose an imaging algorithm that is compatible with the characteristics of microwave photonic imaging radars. This paper first summarizes the development of microwave photonic imaging radar. Then analyzes the typical problems in the imaging process of microwave photonic radar, and proposes corresponding solutions to these problems. Finally the processing results of some measured data of microwave photonic imaging radar are shown.

A recently proposed frequency hopping receiver based on the simultaneous photonics filtering and digitizing system can provide large receiving frequency range as well as high hopping speed by rapidly tuning the optical sampling pulses. With the increase of the hopping speed, the shape of the optical sampling pulses is changed rapidly, and the receiving performance, including the off-band suppression and receiving bandwidth of the proposed frequency hopping receiver is degraded. The performance degradation is indicated in experiments, evaluated theoretically, and analyzed by numerical simulations. Simulations on the shortest frequency hopping time indicate that the receiving passbands are broadened less than 10% with more than 25 sampling periods, and less than 1% with more than 225 sampling periods. The proposed frequency hopping receiver can receive frequency hopping signals with higher hopping speed by utilizing higher sampling rates.

Partial discharge (PD) is an early warning for deterioration of oil-paper insulated equipment, which seriously endangers the safety of power system. It is significant to realize online detection of PD in oil-paper insulated equipment. Due to the advantages of anti-electromagnetic interference and locating the discharge source, the acoustic emission (AE) method is widely used in online PD detection. Conventional piezoelectric transducer (PZT) acoustic sensors cannot be installed inside equipment in practical applications, resulting in low sensitivity and susceptibility to electromagnetic interference from electrical equipment. To solve the above issues, an ultrasonic sensor based on Fabry-Perot (FP) interferometer with gold-coated circular fused silica diaphragm is proposed and experimentally verified. The results show that the fiber optic ultrasonic sensor can be placed inside the oil-paper insulated equipment for partial discharge detection, and has higher sensitivity compared with the traditional PZT.

In modern complex battlefield environment, it is important to obtain the frequency spectrum precisely. We propose an operational method of instantaneous frequency measurement (IFM) assisted by photonics, which can achieve high precision based on stimulated Brillouin scattering (SBS), giving the credit to the narrow linewidth of gain spectrum of SBS. By setting the scanning frequency, the amplitude comparison function (ACF) can be formed in the narrow lineband based on SBS effect. And the measurement of full frequency band is realized through a reference signal, the measured frequency range is limited only by photoelectric device. Estimation of multiple RFs can also be achieved with a resolution of 250MHz. In the numerical simulation, the average measurement error less than 1MHz is achieved in this scheme.

We propose a novel image-like channelization method that utilizes a convolutional recurrent neural network (CRNN) for channel synthesis to reduce the bandwidth requirements of the electrical hardware. In this study, the spectrum of a 30-GBaud QPSK signal is spectrally sliced and received by four low-speed coherent receivers based on a conventional coherent optical communication system. After the recovery of the trained CRNN, the average error vector magnitude (EVM) of the 30-GBaud baseband signal is improved from over 60% by uncorrected channel synthesis to around 15%.

The large array multichannel detector itself has the problems of inconsistent dark current and uneven response between various channels, and after geometric splicing, the image output uniformity between multiple detectors is lower, which is difficult to meet the requirements of further image processing such as target recognition, early warning, tracking, prospection and so on. This paper researches the output image uniformity of multichannel large array detectors after splicing based on the integrating sphere radiometric calibration system, aiming at the problems of high difficulty in real-time imaging correction of space multichannel large array camera and the storage capacity of correction coefficient per pixel limited by hardware, a multichannel large array image uniformity adjustment approach applied to space camera is proposed. Firstly, the dark current correction is carried out to make the detector response consistent under the condition of full darkness. Then the edges of image points in adjacent boundary regions are fitted, and the correction coefficient is obtained. Finally, the correction coefficient is modified according to the saturation value of detector response. This approach significantly improves the uniformity and continuity of large array multichannel spatial remote sensing camera images, which provides the basic guarantee for subsequent image processing such as target recognition and tracking to improve the sensitivity and reduce the false alarm rate. This approach has few correction coefficients, small storage capacity and low hardware implementation difficulty. It has important reference significance for improving output uniformity of stitched focal plane images of large field of view space remote sensing cameras.

Optical fiber sensor is a kind of passive optical fiber device, which has the advantages of small size, high precision, strong anti-electromagnetic interference ability, easy wavelength division multiplexing, good compatibility with the structure to be measured, etc. It can measure various physical quantities such as strain and temperature, and it is easy to realize distributed measurement. With the development of solid rocket motor shell materials from metal materials to composite materials, it is also possible to embed optical fiber sensors for measurement. In this paper, the method and technology of embedding the optical fiber sensor into the composite solid rocket motor shell are designed, and the physical experiment is carried out. It shows that the method of embedding the optical fiber sensor into the composite solid rocket motor shell for strain testing is feasible, which can provide technical support for smart rockets and smart weapons.

Dichroic mirrors, as core optical elements, are widely used in biomedical testing instruments based on the principles of absorbance detection, fluorescence detection and Raman detection. In this paper, the application principle of dichroic mirrors for biomedical detection was introduced, and some key technical indexes for high-performance dichroic mirrors were proposed according to their application characteristics. With the equivalent layer substitution method, a dichroic mirror film system of high-performance based on two conventional materials was designed. Using the plasma assisted reactive magnetron sputtering technology, the dichroic mirror film system with 146 layers was coated, and a kind of dichroic mirror with some important technical indicators such as high steepness (<1%), depolarization (polarization separation <3.5nm), wide range of high transmission (T>96% range > 300nm) was manufactured. The influence of wavefront distortion of dichroic mirror on imaging was described in detail. Our dichroic mirrors can meet the performance of low transmitted wavefront distortion (TWD<λ/4) and low reflected wavefront distortion (RWD<λ/2). The manufactured dichroic mirror products showed satisfying application results when used in high-end medical testing instruments with fine imaging requirements.

Spherically Bent Crystal Analyzers (SBCAs) are the core optical components of x-ray spectrometers. They have been widely used in many x-ray spectroscopy end-stations at synchrotron radiation and x-ray free electron laser facilities around the world. Owing to the monochromatic and focal properties of SBCAs, x-ray spectrometers with high efficiency and high energy resolution can be well applied to the study of x-ray absorption spectroscopy (XAS) and emission spectroscopy (XES). Hence, the quality of SBCAs is the key factor in determining the performance of x-ray spectrometers. Previously, we have investigated the focal properties of Si(444) SBCAs by using a laboratory’s Rowland circle device. However, the original device is limited by movement distance of motors and the space between detector and x-ray source. It is only applicable to SBCAs with a radius of curvature of 500 mm, and the maximum Bragg angle is 86°. Here, we present a new simple near backscattering detection device, which is based on a long linear guideway, to inspect the surface morphology, crystal face morphology, and focal performance of SBCAs at Bragg angle of 88°. By simply adjusting the distance between the source, SBCAs, and detector, focal performance at the focal point can be detected, while crystal face can be imaged off the focal point. By switching the x-ray source to the LED light source, surface morphology is able to be imaged as well. Furthermore, SBCAs with different radius of curvatures within 1000 mm are all measurable by this new device.

In this paper, we propose and demonstrate a novel Tilted Fiber Bragg grating (TFBG) sensing demodulation scheme based on microwave photonic technique. In the proposed approach, the optical power spectrum from BBS (Broadband source) is shaped by a TFBG and then sent to a dispersive element to perform the linear wavelength-to-time mapping. A nonuniform microwave photonic filter with the center frequency depending on the shaped optical spectrum is obtained at the output of a high-speed photodetector. The central frequency and the envelope of the generated microwave photonic filter will shift according to the change of environment. Theory and a proof-of-principle experiment are implemented to verify the proposed approach.

In order to realize the high precision alignment of a catadioptric infrared optical system and improve the imaging quality of the system, a method of using visible light interferometer, infrared interferometer and articulated arm to align infrared optical system was proposed in this paper. First, the characteristics of the infrared optical system were introduced, and the alignment tolerances of each optical element were simulated and analyzed. Then, by aligning the R-C system of primary mirror assembly, the primary mirror assembly reference was extended to the mechanical mechanism, which provided the reference for subsequent precise alignment. The articulated arm was used to monitor the three-dimensional position of the lens assembly, in order to ensure the accuracy of the lens assembly initial alignment. Finally, the infrared interferometer was used to monitor the wavefront aberration of the system, and the relationship between the misalignment of the lens assembly and the zernike coefficient of the system was established, which could guide the alignment work, clear the direction of alignment, and finally realize the accurate alignment of the optical system. The experimental results indicated that the wavefront aberration values of the optical system were better than 1/15 λ (λ =3.39 μm), and each field amplitude transfer function(MTF) was better than 0.25, which met the requirements of imaging quality. It provided a feasible way for the catadioptric infrared optical system to be aligned, and also could be extended to the alignment of the remote sensors of similar structures space flight and aviation.

Single crystal silicon carbide (SiC), the third-generation semiconductor material, has many advantages, such as wide band gap, low thermal expansion coefficient and high thermal conductivity, etc. It has a wide application space in the field of electronic equipment. Its surface quality has great influence on the performance of electronic devices. Therefore, the ultrasmooth polishing of single crystal silicon carbide is very important. At present, the main problems of single crystal silicon carbide processing are poor surface quality and low removal efficiency. In this paper, the ultra-smooth and efficient polishing of single crystal silicon carbide materials is the main research goal. The polishing experiment is carried out by using a uniaxial polishing machine, and the computer-controlled optical shaping (CCOS) immersion polishing is introduced. To achieve super smooth and efficient polishing of single crystal silicon carbide, the corresponding polishing fluid was prepared by Fenton reaction for chemical mechanical polishing (CMP), and KMnO4 polishing fluid was also used for CMP. A series of experiments were carried out by setting different process parameters. The effects of pH value of Fenton fluid, catalyst concentration, type of polishing pad on polishing efficiency and surface roughness were studied, and the influence rules on polishing effect were summarized, so as to seek the optimal process parameters and realize ultrasmooth and low defect polishing of single crystal silicon carbide by combination.

In this paper, the geometric structure of the nozzle in fluid jet polishing is optimized by computational fluid dynamics simulation. The design of small-diameter nozzle is carried out, the relationship between nozzle structure and fluid movement is analyzed, and the influence of machining error on nozzle to fluid stability is considered. Firstly, according to Bernoulli's Principle, the velocity at the nozzle outlet is theoretically calculated, and the holding length of the outlet velocity is defined. Based on computational fluid dynamics simulation, the ability to maintain fluid energy of different nozzle diameters with different length-diameter ratio is analyzed. The results show that the larger the nozzle diameter, the smaller the effect of the length-diameter ratio on the ability of maintain fluid energy. The divergence ratio is defined to explain the ability of constraining the divergence of the fluid. The larger the diameter, the smaller the influence of length-diameter ratio on the position of peak shear force. Then, aiming at the verticality of the cylindrical section in nozzle outlet caused by machining error is difficult to guarantee, the influence of inclination of cylindrical section on ability to maintain fluid energy and constraint the divergence of the fluid is analyzed. The shear force distribution on the workpiece surface still presents a circular shape within the inclination angle is small, and the acceptable error range of inclination angle is given. Finally, a fixed-point experiment of nanoparticle jet polishing is carried out on the surface of fused quartz, and the material removal profile is obtained.

Aiming at the problem of obvious diffraction when light encounters small-diameter components during transmission, we analyze the diffraction effect of micro-lens arrays in this paper. Since the fill factor of the micro-lens array determines the amount of light entering the system, which affects the diffraction effect, and ultimately affects the imaging quality together with the diffraction of the small components, we first use the scalar diffraction theory to analyze and establish the mathematical model of the fill factor of the aperture array and propose a theoretical calculation method. According to this method, different forms of aperture arrays with the same fill factor can be given through geometric relations and system parameters, and then we use an optical analysis software VirtualLab to simulate the diffraction effect. By comparing the light intensity distribution forms and exploring the diffraction effect of the aperture array form on the imaging quality, corresponding conclusions are drawn and a more advantageous structural form is selected.

In this paper, a novel optical vector analyzer (OVA) is proposed and experimentally demonstrated by us based on coherent optical frequency modulated continuous-wave (FMCW) interferometry. The optical vector analysis of optical devices under test (ODUTs) maintains high accuracy despite strong sweep nonlinearity with our method. Basically, due to the linear frequency sweep of optical FMCW, the beat photocurrent consisting of a baseband frequency (BF) signal and an intermediate frequency (IF) signal is generated. Usually we extract the IF signal by filtering and then Hilbert transform to get the frequency response. However, when the sweep nonlinearity is strong, the spectral overlap will occur, and simple filtering will cause severe distortion. We innovatively introduced a common mode branch whose signal is the same as the BF signal in the beat photocurrent. Due to the introduction of the common mode signal, the non-aliased IF signal can be extracted without filtering, which solves the measurement distortion caused by spectrum aliasing and filtering. What’s more, an optical tunable bandpass filter (OTBPF) is added to the correction path to locate the optical frequency for the first time. The phase-shift-fiber grating (PS-FBG) in 1550nm band is measured, and the effectiveness of this method is verified. We eliminate the distortion brought about by the spectral aliasing and filtering with the introduction of the common mode signal path and the measurement accuracy is greatly improved. Frequency response resolution accuracy of this method reaches 33MHz which is mainly limited by the presentation difference.

The microlens array (MLA) scanning system is a relatively new solution for beam scanning, and are used in numerous applications, such as laser radar and optical communications. Excrescent light generated by overlapping divergent beams from adjacent microlenses increases with scanning angle and as a result, the rays do not fill the clear aperture of the MLA. The fill factor is proposed to characterize the fill rate of beams, and its effects on the point spread function (PSF) and modulation transfer function (MTF) are analyzed, this work can benefit the design and evaluation of MLA systems.

With the development of the micro/nano machining technology, various devices tend to be miniaturized and lightweight. Micro-optical elements as one of most important devices, for its easy integration and broad functions, has been extensively studied. Microlens have been widely used in the fields of imaging, detection and sensing. In order to enhance the stability and broaden the application environment of the microlens, fabricating the microlens based on hard and brittle materials is necessary. Hard and brittle material different from soft materials, which have high thermal and mechanical stability, and have the ability used in harsh conditions. In this study, we combined femtosecond laser single pulse fabrication with HF wet etching on fused silica to realized concave microlens on fused silica. Moreover, microlens with different focus can be realized by adjusting fabrication parameters. The results indicated that the fabricated microlens have excellent focusing and imaging properties. The femtosecond laser single pulse fabrication assisted with HF wet etching exhibits high flexibility and shows the huge potential of fabrication micro-optical elements on fused silica.

In recent years, with the development of rotation direct measurement instruments, rotational seismology has gradually become a hot field, and it is proposed that observation needs high sensitivity. The rotational seismometer based on fiber optic gyroscopes (FOG) has gradually become the preferred choice for seismic rotation observation due to its insensitivity to translational motion, fully solid state and high sensitivity. In order to meet the demands of multi station observation network in seismic exploration, the FOG which is the core sensing element of the rotational seismometer, needs to have the characteristics of high sensitivity and low cost. In this paper, a budget-friendly dual-polarization FOG scheme based on a Lyot depolarizer is proposed, and the ports difference method is employed to suppress the short-time noise and improve the sensitivity. The experiment adopts 2km polarization maintaining fiber ring, and the two ports have stable output. After the difference of the two port signals, the self-noise over 0.03Hz~50Hz is reduced from 260nrads^-1Hz^-1/2 to 120nrads^-1Hz^-1/2. It shows that the rotational seismometer using this structure has low cost and high sensitivity, and has a good application prospect.

In recent years, terahertz communication has attracted extensive attentions due to its large bandwidth for supporting terabit-per-second capacity. Along with the rapid evolution of terahertz optoelectronic devices, remarkable achievements have been witnessed in developing photonic terahertz communication systems with large capacities. In fact, photonics-assisted terahertz communication systems have exhibited some advantages, for instance, bridging a seamless connection between the existing optical fiber network and wireless network, offering flexible carrier switching over a wide radio frequency range, as well as supporting easy implementation of high-order complex modulation formats and multicarrier multiplexing terahertz channels. However, due to high atmospheric propagation loss, limited terahertz component bandwidth and low terahertz emission power, achieving simultaneous transmission of single-lane data rates beyond 200 Gbps is still challenging based on a single pair of terahertz transceivers. In this work, by employing subcarrier (SC) multiplexing, high-order 64-ary quadrature amplitude modulation (64-QAM) format, well-defined digital signal processing (DSP) and wideband terahertz transceivers, a multicarrier terahertz photonic-wireless communication link operating in the 300 GHz band is proposed and experimentally demonstrated. At the transmitter side, a baseband pseudo-random binary sequence (PRBS-15) signal with a baud rate of 12 Gbaud is generated from an arbitrary waveform generator (AWG), and then modulated onto an optical carrier centered at 193.414 THz. The modulated optical signal is combined with three optical carriers centered at 193.7035 THz, 193.7165 THz, and 193.7295 THz, for multi-carrier THz generation at a uni-traveling carrier photodiode (UTC-PD) featuring large bandwidth (100 GHz), which consists of three SCs centered at 286.5 GHz, 299.5 GHz and 312.5 GHz, respectively. At the receiver side, we employ a Schottky diode mixer with high sensitivity to down-convert the three terahertz SCs into the intermediate frequency (IF) domain, with three IF signals cantered at 6.5 GHz, 19.5 GHz, and 32.5 GHz, respectively, which are then processed using home-made advanced DSP routine, including a linear adaptive equalizer, compensation algorithms of frequency offset and phase noise. In the experiment, a total line data rate of 216 Gbps (72 Gbps/SC × 3 SC) over a wireless distance of 30 m is successfully transmitted, and the performance of all three SCs can reach below the hard decision forward-error-correction (HD-FEC) with 6.25 % overhead, reaching an aggregated net transmission capacity of up to 202.5 Gbps. This achievement of single-lane simultaneous transmission of beyond 200 Gbps using a single pair of 300 GHz transceivers is considered a significant step towards next-generation wireless communications.

The optical beamforming network (OBFN) is a promising alternative of traditional electronic phase shifter due to the advantage of eliminating the so-called beam squint behavior. Herein, a series of optical true time delay lines (OTTDLs) based on silicon on insulator (SOI) platform are proposed to produce OBFNs with multi-beam steering characteristics. A series of OBFN chips is designed to realize 34 specific delay steps between -21~+21 ps in order to achieve a nominal equal difference beam steering angle between ±45°. To pursue good beam quality, 32 delay waveguide channels are proposed according to the number of array elements. The optical carriers in each channel are densely multiplexed off-chip with a frequency difference of 100 GHz in C-band, and coupled on-chip by a grating coupler. Variable optical attenuators (VOAs) based on Mach-Zehnder interferometer (MZI) structure are introduced to tune the optical outputs of the 32 channels with a discrepancy less than ±1 dB. The OTTDLs are compatible with CMOS process, and appeared in a compact footprint of only 0.163 mm² for a maximum true time delay of 651 ps. Such a compact waveguide layout leads to the footprint of a single chip within 2.5 mm×7.5 mm. Meanwhile, the operating temperature is under closed-loop control via a pair of thermoelectric cooler (TEC) and negative temperature coefficient thermistor (NTC). Together with hermetic package, the reliability of the OBFN chips can also be promoted.

We propose a novel method to optimize the transmission performance of the UWB-over-fiber system. In the proposed UWB-over-fiber system, an UWB signal generator based on microwave photonics is used as the signal source in the central unit. The UWB signal generator is used to generate high-order UWB signal. Direct sequence binary phase shift keying (DS-BPSK) modulation and convolutional coding are applied to the baseband UWB signal. The dispersion and transmission loss of the fiber can be compensated by a chirped fiber Bragg grating and an erbium-doped fiber amplifier, respectively. The coherent receiving technology is applied for demodulation, and the Viterbi decoding technique is used for channel decoding. The feasibility of the proposed scheme is demonstrated by simulations. At the forward error correction (FEC) threshold of 3.8×10×⁻³ , the receiver sensitivity is around −16 dBm and the power penalty is around 0.2 dB, after 25-km fiber transmission.

The classical Preston equation considers that the material removal is linearly related to time, velocity, and pressure. However, in the wheel polishing technology, it is found through experiments that there is a nonlinear relationship between the rotational speed of the polishing wheel and the amount of material removed. In order to accurately control the material removal in the polishing wheel variable speed machining strategy, it is necessary to modify the classical Preston equation. In this paper, the control variable method is used to carry out the sampling experiment: the time and pressure are set as fixed values, and the polishing wheel speed is set as a variable and the value is between 0-4rps. Then the data points were analyzed and a least squares fit was used to obtain a non-linear function between the rotational speed of the polishing wheel and the amount of material removed. Finally, the classical Preston equation is modified to obtain the removal equation suitable for the variable speed machining strategy.

With the development of science and technology, the industry has an increasing demand for high-precision optical detection, such as wave aberration detection of the lithography objective lens, the core component of the lithography machine . System errors inevitably exist in the process of optical detection. Because the random averaging method has the characteristics of simple operation, this paper studies the system error calibration of the measuring device based on the random sphere method. Rotate the direction of the ball lens with a certain accuracy at random in the optical path, eliminate the random error in the measurement system and the uneven error of the spherical lens surface on average, and then subtract the inherent spherical aberration of the ball lens from the average measurement data to realize the measurement. Self-calibration of device systematic errors. The experimental platform for the verification of this method includes: a 632.8 nm light source, a 10 μm pinhole, a common lens, a spherical lens with a refractive index of 1.52 and a diameter of 40 mm, and a SID4 camera. After experimental verification, the method can realize the purpose of calibrating the system error of the measuring device with high precision and low cost by using a low-precision ball lens.

A high-sensitivity optical fiber acoustic probe based on extrinsic Fabry-Perot interferometer (EFPI) is designed, fabricated, and analyzed. The sound sensitive diaphragm fabricated by silicone rubber exhibits excellent properties including good adhesion, high mechanical strength, flexibility, aging resistance, and biocompatibility. The acoustic pressure change introduces the periodic vibration of silicone rubber diaphragm, which causes the fluctuation of the output voltage. The FP cavity is formed by a cleaved end face of fiber and the silicone rubber diaphragm. The silicone rubber is prepared by a simple spin-dip method, which is easy to fabricate and suitable for mass production. A high acoustic pressure sensitivity and a high signal-to-noise ratio (SNR) of 387 mV/Pa and 48 dB at 1.5 kHz were obtained, respectively. The sensor is expected to be suitable for photoacoustic spectroscopy, week acoustic detections and biological application.

AlON ceramic is widely used in the fabrication of high-quality infrared optical components, and has broad application prospects in aerospace, transparent armor, and infrared weapon windows. A laser can be applied to the processing of AlON ceramic in order to achieve a more flexible and efficient processing of AlON ceramic. In this paper, laser drilling experiments were carried out on AlON samples to investigate the mechanism of laser processing of AlON ceramic. A two-dimensional simulation model of laser ablation of AlON ceramic was established, and the process of material removal was analyzed. By comparing the experimental results with the theoretical analysis, the effect of defocus distance on the quality of AlON laser processing is analyzed.

In order to explore the dynamic variation rule of temperature distribution on surface of optical element, the temperaturerise effect of atmospheric plasma processing was analyzed by using simulation model, and the corresponding thermal stress mathematical model was established for fused silica. On this basis, the experiment of plasma processing was carried out, the dynamic variation rule of temperature distribution on surface of four materials of aluminum, aluminum alloy, SiC and fused silica during the atmospheric plasma processing was analyzed, and the verification and comparison with the simulation results were carried out. The results show that the arc discharge atmospheric plasma polishing technology can effectively remove the damage layer of fused silica optical element by physical polishing, and the simulation model can provide data support for the atmospheric plasma processing technology.

The macroscopic property of optical material depends on the chemical composition as well as its mesoscopic structure. Thus, the processing of micro- and nanostructures of soft matter, including liquid crystal, is of great importance and can be exploited in many areas. The laser-assisted mechanical injection brings the concept of laser micro-nano manufacturing to the field of liquid crystal (LC) and injects a certain number of microdroplets (MDs) of the water solution with a uniform size into a host LC drop by using a laser beam. With the help of the elasticity of the LC medium, the injected water MDs spontaneously self-assemble into colloidal crystals as inner structures within the closed 3D space of the host LC drop in the microscale. The self-assembly structure of injected MDs in 3D has been scanned using the confocal microscope. In addition, by introducing the cholesteric LC drops with a topological defect line as the host, the injected MDs are captured by the defect line and self-assembled along its geometry into a chain. Moreover, it is proved that laser-assisted mechanical injection is also available for the interface of two immiscible fluids with a relatively high viscosity. The results provide a new method for fabricating and developing customized hierarchical microemulsion, drug delivery system, biosensor, and functionalized microstructure of soft matter.

The sol-gel antireflective films have been applied in Large-scale, high-power laser facility for several years to improve its output capability. While, the loose, porous films are under the baneful influence of contamination. The concentration of contamination and the optical properties of films are difficult to be measured when the laser facility is operated. Therefore, it will be important to study the stability of optical property of the coated substitute optics. To study the optical property stability of films in different environments, the samples coated with technological process at present were placed under 10⁵Pa, 10³Pa, 10^-3Pa in laser facility, and spectrum transmittance of them was tested before and during the storage. The spectrum transmittance decrease of the films with storage time is described quantitatively. The tested results shows that, the sol-gel antireflective films consequently can maintain its high transmittance under room pressure. The transmittance will be decreased significantly under 10^-3Pa owing to plenty of contamination. The test under 10³Pa shows that there is much more contaminants on higher fluent. Further experiment after intensified NH₃ and HMDS posttreatment has been performed at the same time. The results shows that these samples have lower rate of the transmittance decrease. Both the control of the cleanliness and the intensified post-treatment will extend the lifetime of the sol-gel antireflective films.

As the most widely used optical structure, coaxial optical system has become the critical component of many elaborate compound machines. However, with the development of science and technology, aerospace and lithography technology has put forward higher requirements on the imaging quality of ultra-precision coaxial optical system. And the optical axis consistency condition plays a critical role in the system imaging quality. In this paper, the dual optical path system based on light splitting prism is introduced, in which the coaxiality of the dual optical path become a critical issue. For the high coaxiality assembly, the optical centering assembling technology based on optical imaging principle is applied to ensure the coaxiality among the optical axis of optical element, the rotation axis of corresponding machine part and the rotation axis of lathe. According to the optical auto-collimation imaging principle, the visualization and transmission of the main datum of the optical system is completed, which will ensure the datum conversion completed with high precision. Finally, the experiment has been conducted and the coaxiality of the actual dual optical system is better than 0.05mm.

An ultra-wideband random OEO using both stimulated Brillouin effect and Rayleigh scattering effect is proposed, which can generate random oscillating microwave signals covering all frequency bands. By using stimulated Brillouin scattering effect to amplify weak reverse Rayleigh scattering, the microwave signals with random characteristics which is independent of fixed cavity length can be generated. Experimentally, the work realized the generation of ultra-wideband (DC up to 32 GHz) random microwave signals. Compared with previous methods，the proposed random OEO mechanism is realized in an easier way, which can avoid using 1450 nm laser and promote its application in electronic interference.

In this study, a coded aperture collimator and a 3D position-sensitive detector are combined to form the detection part of the coded aperture imaging system. Different types of detectors are irradiated with radioactive sources of different energies through the Monte Carlo method, and the depth information of detectors is studied on imaging performance. In the simulations, the coded collimator adopted the M-M coded method, and the detector types used included CZT, GAGG(Ce), NaI(Tl), CsI(Tl) and BGO. The detector arrays of different layers are reconstructed by direct convolution algorithm. The simulation results showed that when the gamma-ray energy was 60keV, the SNRs of the reconstructed images in the first layer array of various detectors were similar, reaching about 65, and the images in other layers could not be reconstructed accurately. For the gamma-rays with energy in the range of 122keV-511keV, the SNRs of reconstructed images in each layer of various detectors showed a step-like decline, and the SNRs of the reconstructed images in the first layer of the 3D position-sensitive detectors were greater than that of the conventional detectors. When the ray energy was 662keV or above, the SNRs of reconstructed images in each layer of various detectors were similar, especially for detectors with low density. Moreover, the SNRs of the images in first layer of all types of detectors were lower than that of the conventional 2D position-sensitive detectors, demonstrating that the depth information could not improve the detection performance for the energy above 662keV. Using the full-energy peak for image reconstruction had not improved the SNRs, because the majority of interactions were scatters events in this energy end. From the perspective of the whole energy range, the difference of the SNRs between each layer of BGO detector was the largest, when that of NaI(Tl) detector was the smallest, which was determined by the blocking ability of the detector. The angular resolutions of the reconstructed images in different layers of the 3D position-sensitive detectors for different energy rays varies slightly, whose values were about 2.9° (along the x-axis direction).

Lamost can precisely locate 4,000 optical fibers according to the star catalog position within a few minutes, which greatly improves the observation efficiency. There is no blind area, and the observation area of the fiber optic unit must be overlapped, but this will cause the adjacent units to collide during the movement process. Once the collision occurs, the observation accuracy and service life of the unit will be reduced. In order to solve the collision problem between optical fiber units, this paper proposes an anti-collision planning scheme for optical fiber units based on the idea of divide and conquer weighting. This scheme simplifies the overall collision problem into a small set of collision problems. The unit sequential is adjusted, and simulation experiments show that, compared with the commonly used path planning scheme, this method can better improve the observation efficiency of astrological phenomena and reduce the processing times of the unit.

An all-fiber mid-infrared enhanced supercontinuum laser source, spanning from ~2 μm to ~4.2 μm, was demonstrated in an erbium-doped ZBLAN fiber amplifier. A 2 μm low repetition rate noise like-pulse mode-locked fiber laser was adopted as the pulse seed for the system. Thanks to using a new-type homemade silica-fluoride fiber pump combiner, the 2.8 μm pulses in the supercontinuum were amplified in the erbium-doped ZBLAN fiber amplifier with all-fiber structure. Due to soliton self-frequency shift, long wavelength components were generated and a 1.4 W mid-infrared enhanced supercontinuum with up to 97% of the power beyond 2.7 μm was obtained in the erbium-doped ZBLAN fiber. This research demonstrated a compact and simple in-amplifier mid-infrared supercontinuum generation with all-fiber structure.

In this paper, the assembly and rectification method of the new optical system is studied. According to the characteristics and difficulties of the diffraction camera, the assembly and rectification scheme is formulated. Firstly, the space angle of the mirror is determined by the spatial attitude measurement and the reference conversion matrix method. The coaxial adjustment and combined detection and adjustment of each transmission lens group are completed by the self alignment method. The method of sensitivity matrix iterative fine adjustment based on aberration is applied in the whole machine assembly and adjustment process. Finally, the high-precision assembly and detection of the complex offset axis infrared diffraction camera were completed, and the wave aberration on the axis reached 0.119λ@3.39μm. The MTF reached 0.13@33lp/mm, meeting the design requirements. This method provides engineering experience and reference for similar camera assembly and adjustment process methods.

Optical freeform surface with high geometric complexity requires appropriate sampling strategy to achieve holistic measurement with improved efficiency and accuracy. This paper presents an adaptively sampling plans to measure the points based on particle swarm optimization algorithm for the problem of freeform surface measurement. In order to provide mathematical foundation for parametric modeling of freeform surfaces, the mathematical model of the freeform surface was then analyzed. The particle swarm optimization algorithm was studied, and the error optimization function between the interpolation surface of sampling points and the original freeform surface was constructed, and the coordinates of the sampling points were converted into particle positions for optimization, so as to distribute the sampling points adaptively. Simulation studies was conducted by using serval complex freeform surfaces. The results shows that the adaptively measured points can achieve the optical surfaces with improved accuracy and with less sampling points compared the traditional method.

On-orbit Assembling Space Telescope (OAST) technology, which was firstly presented by NASA around early 2000s, is one of the most feasible paths to the implement of 10m-class aperture large scale space telescope. Unlike traditional monolithic aperture telescope (like HST) or deployable space telescope (like JWST), OAST is modularly designed, modularly manufactured and modularly launched, the telescope modules are assembled and co-phased to diffraction limit in spatial environment. Considering the development of OAST involves multiple interfaces and new subsystems, on-orbit assembling and aligning procedure, the top-level design methods and considerations are quite different from monolithic space telescopes. this article introduces and discusses several op-level design consideration including optical and mechanical structure, on-orbit assembling and aligning method, and on-orbit testbed developing method.

Neutron and X-ray CT are powerful nondestructive testing techniques, they can penetrate sample, interact with the material, and comes out internal structure information in three dimensions. However, as the neutrons and X-rays interact with elements by different mechanisms, imaging by them can be used to provide a better understanding of the samples. The Energy-Resolved Neutron Imaging instrument (ERNI) in Chinese Spallation Neutron Source (CSNS) is equipped with in situ X-ray micro-CT which is used to combine neutron CT and provide more structure and composition information of sample. The designed best resolution of the X-ray imaging system is 2 micrometers when using the minimum operating power, also a favorable compensation for neutron imaging whose resolution is about 40 micrometers.

With the development of ultra-precision machining technology, parts with microstructures on the surface are playing an increasingly important role in engineering practice. The scanning interference microscope measurement method is widely used in the measurement of microscopic surface topography. This paper proposes a method of interference microscopy combined with subaperture stitching. The first step is to divide and measure the sub-aperture. There is a partial overlap area between the divided adjacent subapertures. The white light interferometer measures each sub-aperture in turn. The second step is edge feature detection. There are highly steep edge features between the bottom of the groove and the surface of the surface microgroove. The stitching algorithm detects edge features by detecting the slope threshold of the sub-aperture. The third step is to correct the abscissa. Project the detected edge feature data onto the OXY plane to generate a 2D data set. The multi-dimensional motion scanning platform inevitably has motion errors in the measurement process, so the edge characteristic curves of adjacent sub-apertures have obvious lateral displacement in the overlapping area. The lateral displacement and angle of the lateral coordinate of each sub-aperture are corrected by the least square method. The fourth step is the height coordinate correction. The stitching algorithm minimizes the height difference between the corresponding points in the overlapping area, and solves it with a linear least squares problem model. We have completed the measurement of the fringe pattern on the computer-generated hologram (CGH) substrate and the complete topography of the long groove on the 10mm hemisphere. After the sub-aperture global iterative stitching algorithm, there is no stitching trace in the simulation result. For the long groove on the hemisphere, we designed a four-dimensional scanning motion platform and a special fixture to ensure that the long groove on the hemisphere rotates around an axis perpendicular to the geodesic line. The center of the white light interference fringe is always at the center of the long slot aperture.

It is expected that the ongoing and future space-borne planet survey missions including TESS, PLATO will detect thousands of small to medium-sized planets via the transit technique, including over a hundred habitable terrestrial rocky planets. To conduct detailed study of these terrestrial planets, particularly those cool ones with wide orbits, the exoplanet community has proposed various followup missions. The currently proposed ESA mission ARIEL is a first step for this purpose, and it is capable of the characterizations of planets down to warm super-Earths. The NASA HabEx and LUVOIR missions are mega projects to further tackle down to habitable rocky planets, which are now merged and to be launched in 2040-2045 if approved. In the meanwhile, China is funding a concept study of a 6-m class UV to optical space telescope named Tianling (a Chinese word meaning neighbours in the sky) that aims to start its operation around 2035 and last for 5+ years. Tianling will be mainly dedicated for the characterization rocky planets in the habitable zones (HZ) around nearby stars. We describe briefly the concept study of this mission and propose a baseline requirement of the telescope and instrumental parameters based on our preliminary simulation results.

Based on chemical-mechanical polishing and combining mechanical and tribochemical polishing techniques, a precision lapping method suitable for parabolic polishing specified by grazing incident X-rays is introduced. Various factors affecting the polishing process are analyzed, and the results show that the proposed method is consistent with Preston's equation and Hertz contact principle. Therefore, this paper proposes a general material removal model based on the above two methods. The mid and high-spatial frequency errors are demanded to reach the requirements with an angular resolution consistently < 6 arcsec HEW and a roughness of 0.3 nm rms (between 1 mm and 0.002 mm spatial frequency range). To achieve the conformal ultra-smooth polishing of focusing mirrors, the process of full-aperture super-smooth pitch polishing is investigated. The influences of key polishing parameters are revealed. The evolution of the surface topology has been studied. A polishing setup is established to carry out experimental polishing to verify the optimum processing parameters obtained by simulations and previous polishing tests. Besides, the effect of abrasive particle size on the roughness is also verified. The roughness of the polished mandrel is measured at different positions, and the optimum roughness reaches Ra 0.359 nm. The polishing approach can significantly reduce the surface roughness of the replication mandrel, satisfying the low energy band focusing requirement of grazing incidence X-ray mirrors.

Optoelectronic Oscillator (OEO) adapts photoelectric hybrid method to realize a high frequency precision and high stability through optical fiber energy storage and delay method, which is generally better than microwave oscillator. This paper outlines the composition, working mechanism, and the design principles of a millimeter-wave OEO system. Additionally, the effects of long fiber and filter on the OEO loop and its phase noise have been experimentally demonstrated. In the experiment, a phase noise of -98dBc/Hz@10kHz can be observed from a 31.4GHz signal generated by the OEO.