This PDF file contains the front matter associated with SPIE Proceedings Volume 8418, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

As semiconductor feature sizes continue to shrink, the allowable error margins for Critical Dimension (CD) is getting increasingly tight. However multiple errors are inherent in the lithography system which could have severe impact on CD control and process latitude. It is indispensable to analyze and balance the influences of various errors in order to get larger tolerance for errors within allowable error margins for CD. In this paper, by using PROLITH^TM X3 and in-house software IntLitho, we study the cross-talk of the dominative errors of numerical aperture, coherent factors, mask CD, flare and analyze its influence on lithography performance. The results show that the tolerance for the errors can be released when some errors impact on CD is counterpoised by that arising from another error in usable process window. Moreover multiple combinations of errors or tolerances can be used for such compensations. Finally we supply a method to perform the compensation of multi errors impact on CD and process window, which is the essence of co-design or cooptimization of lithography tool for rigorous CD control.

We consider the problems of focal length and focal depth of subwavelength imaging via a silver slab of metallic superlens. The performance limit of the metallic superlens was associated with the losses in the metallic film. The transmittance through a metal film is quite low and decreases exponentially with the thickness of the metal film. In the visible wavelength region, the permittivity of Ag can be approximated by the Drude model, so it can be described as the plural permittivity. The real part ( Ε′ ) of permittivity of the metal slab has been preferably index matched to the host material, and the imaginary part ( Ε″ ) is considered to prevent ideal reconstruction of the image. Because superlens are usually made of metals with significant intrinsic loss ( Ε″>0 ), the image is blurred and it is regarded as an ultimate limitation to a near field perfect lens. The real part ( Ε′ )and the imaginary part ( Ε″ ) of permittivity of the metal slab is the function of the incident wavelength, so we discuss the relationship of the focal length, focal depth and the incident wavelength. We also derive the expression for the resolution limit of metallic lens and demonstrate that the area of its subwavelength performance is usually limited to the near-field zone.

Although the long-focal-depth (LFD) function of cylindrical microlenses was previously realized by the phase modulation method, however, there still has no report of obtaining a uniform axial intensity distribution through the pure phase modulation mechanism. In this paper, the amplitude modulation mechanism is proposed for designing LFD cylindrical microlenses. An apodized window function of the incident light is used to suppress the axial intensity oscillations, so that a uniform axial intensity profile is achieved. Rigorous electromagnetic theory and the boundary element method are applied to analyzing focal performance of the designed cylindrical microlenses. Through replacing the incident plane wave with a two dimensional Bessel beam, numerical results demonstrate that the designed cylindrical microlens not only holds an LFD property, but also maintains a uniform axial intensity distribution as we expected. Moreover, the designed LFD cylindrical microlens has a high diffraction efficiency on the real focal plane. It is believed that the designed LFD cylindrical microlens with a uniform axial intensity profile should have wide application prospects in many micro optics systems.

A novel curved compound eye imaging system is put forward in this paper. Non-uniform hexagonal lens array is arranged on the inner surface of a plano-concave substrate. Based on the geometrical optics, the parameters of each microlens are set according to the position of the lens, and even orders of aspheric lens are used to correct some primary aberrations. Optical parameters of this configuration are entered into numerical ray-tracing simulations (ZEMAX). The result shows that the new curved compound eye can enlarge the field of view (FOV) approximately 50% compared to the lateral compound eye, and the FOV can be up to 150°. The principles and functions of all parts of system are described in detail. At last, the feasibility of ultra-precision machining is studied in this paper.

Micro V-groove array is a critical fundamental component of optical fiber array for optical communication system of next generation. The accuracy of micro V-groove directly determines the precision of optical fiber array. The test precision of the image method and the light intensity search method can't satisfy the test requirements including micro V-groove pitch and depth currently. A new stylus measurement method is presented for the ultra-precision testing of micro V-groove array. Stylus profilometer is used to travel over the surface of micro V-groove, the measurement data points are fitted by cubic spline curve. The center of optical fiber circle in the V-groove is calculated according to the theory of equidistant line. The least square theory is used to qualify the error of core pitch and depth combined with theoretical analysis of measurement accuracy in the error theory. The impact of deviation error in the workpiece clamping is analyzed, and a differential method is presented to eliminate the deviation error. The experimental result indicates that the new measurement method can accurately detect the precision of micro V-groove array.

This paper introduced a new method to fabricate free-form micro lens array. A conductive template was deformed by applied voltage on its underneath electrodes, and polymer primer was poured in this template to form a micro lens array after curing and de-molding process. A integrate simulation process of the micro lens array was proposed. The geometry of the template at a certain bias was figured out through multiple physical field simulation. Next, a three dimensional solid body was generated surrounded by the deformed surface of the template and a flat surface. Finally, This solid body was input into an optical lens simulation environment to obtain its optical performance. As a demonstration, a PDMS free-form micro lens array was designed and fabricated using this Molding by Electrostatic Force Deformed Template (MEFDT) method successfully. Metal electrodes layer, SU-8 layer and conductive membrane layer were deposited and patterned in sequence to realize the template, and then PDMS micro lens array was duplicated using this template with an applied voltage. Through changing the initial shape of the template as well as the position and bias of the electrodes, this MEFDT method is believed to have the ability to achieve micrometer size lens with precisely controlled geometry.

To realize the measurement of atmospheric parameters, a kind of real time processor based on FPGA and DSP is proposed and designed. When Adaptive Optical (AO) system is close-loop, the FPGA reconstructs the open-loop Zernike coefficients from the close-loop data of residual slopes and corrected voltages, which are used for the later complex statistical calculations of the coherence length r0, the outer scale L0, the wind speed v and the coherence time t0 by the DSP. The errors of the open-loop Zernike coefficients reconstructed by FPGA are less than 3x10^-8 λ ( λ is the wavelength). The errors of the atmospheric parameters computed by DSP are less than 7.8x10^-8 cm (r0), 5.3x10⁻⁵ m (L0), 7.5x10^-7 m/s (v) and 4.0x10^-6 ms (t0), respectively. For 127-element AO system at 1.8m telescope with 2000Hz sampling frequency, the processing latencies of FPGA and DSP are 19.65us and 553.8ms respectively, and the refresh time of atmospheric parameters is 1.85s. The results show that the proposed processor can be used to measure the real time atmospheric parameters.

FDTD method can be used to compute the electromagnetic field scattered by the particles. FDTD method only provides the 6 vector electromagnetic field components ( Ex Ey Ez Hx Hy Hz) in discrete coordinates, and each component located on different physical point of the so called Yee cell. The values of the components are transient in time domain. For calculating the specific problem such as absorption cross section, scattering cross section and extinction cross section of the scatters, we usually integrates the time-averaged Poynting vector across a closed surface surrounding the scatters. The transient values of the field components derived from FDTD located at the Yee Cell grids must be translated into the values of the same physical point at the same physical time to get the time-averaged Poynting vectors. By this way we can get the highly accurate calculation results. The method of integrating the time-averaged Poynting vector over a certain closed surface is given in the paper. Comparing with the method of integrating the divergence of time-averaged Poynting vector over the volume region, our method of face integration is not only much more time saving for large size scatteres, from O(N³) to O(N²) in time complexity, and having a more direct physical meaning, but keeping the same calculating accurateness at the same time. We calculate the scattering efficiencies and the absorption efficiencies of the sphere of gold in 825 nm incident wave length, in size parameter ranging from 0.5 to 10 and from 0.1 to 1, respectively. The results of our calculation are compared with Mie theory, which are analytical results, to verify the correctness and the accurateness of our method. The spring models for simulating nano coil structures are studied by our method.

Photon sieve is a new nano-scale imaging aperture. When the diameter of pinholes of photon sieve is less than the wavelength of incident light, scaler diffraction theory is no longer valid for this condition. So vector theory must be used. The finite difference time domain (FDTD) is an effectual tool of numerical calculation and analysis of light field. We put forward researching high NA photon sieve with FDTD method. First we analyze the imaging properties of a single pinhole of photon sieve with vector diffraction theory and then introduce the principle and realization of FDTD. At last FDTD method is used to the numerical simulation of a pinhole. The simulation results are aslo compared to the results using scaler diffraction theory. It shows that scaler diffraction theory is not valid. The necessity and feasibility of using FDTD method to analyze and design high NA photon sieve is proved.

Critical Dimension Uniformity (CDU) is quite sensitive in 45nm node lithography and beyond, thus, more attentions should be paid on the controlling of CDU. Moving Standard Deviation (MSD) and Mask Manufacture Errors (MMEs) including the Mask Critical Dimension Error (MCDE), Mask Transmittance Error (MTE) and Mask Phase Error (MPE) are the two important factors influencing CDU. The study on the impact of MSD and MMEs is a helpful way to improve the lithographic quality. Previous researches often emphasize on the single impact of MSD or MMEs, however the impact of both of them usually exists simultaneously. The studies on the co-impact of MSD and MMEs are more significant. In this paper, the impact and the cross-talk between MSD and MMEs on Critical Dimension (CD) and Exposure Latitude verse Depth of Focus (EL-DOF) for different pattern under various illumination conditions have been evaluated by simulation, which is carried on PROLITH^TM X3 and in-house software IntLitho. And then, the MSD’s tolerance with the existence of MMEs is discussed. The simulation results show that CD error caused by the co-existence of MSD and MMEs is not the simple algebraic sum of the individual CD error caused by MSD or MMEs. The CD error becomes more pronounced when the MSD and MMEs interact with each other. The studies on the tolerance reveal that the tolerance of MSD decreases due to MMEs’ existence and mainly depends on the mask pattern’s pitch.

More and more factors influence the lithography performance with the shrinkage of Critical Dimension (CD). CD error raised by litho tools imperfection cannot be ignored any more. Flare control and Numerical Aperture (NA) adjustment play a critical role in 90nm node dry lithography. In this paper, the respective and the joint impact of flare and NA error for 90nm dense line, semi-dense line and isolated line have been studied by simulation. The results show that the change of CD error is approximately linear with flare and NA error respectively. CD error and Depth of Focus (DOF) error for dense line are sensitive to the change of flare and NA error, especially the sensitivity of CD error to flare and NA error of dense line is larger than that of semi-dense line and isolated line. The placement error caused by flare and NA error is less than 10^-3 nm for these patterns. The joint impact of flare and NA error on lithography performance is not the linear sum of the results that two factors change respectively; there is a certain coupling effect between these two factors. For these patterns, the sensitivity of CD error to flare is larger than that to NA error, but a larger NA error can compensate the effect caused by flare. Therefore, the tolerance of flare can be relaxed by adjusting NA.

Polarization laser direct-writing system was designed and the recording and research using the azobenzence polymer film on the system was investigated. Only single laser beam was used, and move the laser focal spot on the sample film pointto- point. By composite control of the optical power density, polarization direction and exposure time of the inscribing laser, a special phase-delay distribution graph which have different etching depth in different point can be achieved. Diffractive devices, such as grating and zone plate, have been inscribed. The anisotropy and surface topography was measured by polarizing optical microscopy (POM) and profilometer. Some qualitative analysis was made. Using the red light which is insensitivity to the azo polymer film, the diffractive devices’ focal spots were collected by CCD. Compared with the holographic interference method, the method is more flexible, undemanding for the experimental environment and any two-dimension distribution graph can be written in theory. It may get extensive application.

Patterned microstructured surfaces are widely adopted in advanced optics applications such as LED backlight guide, which can be fabricated by precision roller embossing. Ultra-precision rollers with microstructured patterns are key components for the precision roller embossing process. However, ultra-precision roller is not only difficult to be fabricated due to the heavy load and high precision requirements, but is also expensive in terms of its manufacturing cost. This paper presents a framework for research and development of an ultra-precision roller machining equipment for the fabrication of ultra-precision rollers for the precision embossing of microstructured optics applications. The framework includes the machine design concepts and key technologies, such as the machine mechanical configuration, development breakdown, and some key technologies including roller cutting mechanism, tool path planning and generation, pattern mapping from plane to roller, cutting tool position setup and error analysis, etc. Compared with the existing equipments for ultra-precision roller machining, the designed machine equipment aims to be high precision which can be produced in a low cost. This allows the equipment can be potentially used in mass production to support optical-electro-mechanical industries in Mainland China.

Microtoroidal is of great use in a wide range of fields including photonics, biosensors, micro-lasers, nonlinear optics, cavity quantum electrodynamics(C-QEDs). In this paper we described ready techniques to fabricate microtoroidals, which included photolithography, isotropic wet etching, and CO₂ laser reflow. Two different methods of fabricating biconical optical fiber tapers were also described, which had potential application in near field coupling with microcavity. One of them was to etch a standard single mode fiber(SMF) with buffered hydrofluoric(BHF) acid solution while another was to heat and pull a SMF under control simultaneously. The taper waists as small as 1~3 μm and insertion loss less than 0.46 dB were obtained easily through the two methods. Finally, The values of Δλ_FSR (Free Spectrum Range) and Q (Quality Factor) of a fiber-taper and microtoroidal coupled system were measured.

The quality of the reference wave front in point diffraction interferometer (PDI) is mainly determined by pinhole diameter, pinhole edge roughness and so on. The edge roughness of an actually electric beam etched pinhole is determined by least square fitting method. The Gaussian noise with zero means and σ root mean square (RMS) is added to a perfect pinhole to model the edge roughness pinhole. Based on Rayleigh-Sommegeld diffraction formula, the quality of the far field wave front diffracted by a rough edge pinhole is analyzed in detail. Pinhole edge roughness mainly causes trefoil and coma aberrations in diffracted wave front. For pinholes with diameters from 400 nm to 1000 nm, when the edge roughness σ are 0 nm, 15 nm and 30 nm, the RMS deviation of the diffracted wave fronts are in the order of 10^-8 λ, 10^-4 λ and 10^-3 λ, respectively. The results show that pinhole edge roughness has a significance infection on wave front errors, while it has little to do with the intensity distribution in the diffracted wave front. The edge roughness of the reality pinhole used in PDI is 2.37 nm, and the wave front errors of the wave front diffracted from this pinhole can reach 0.08 nm RMS.

A fast-steering mirror (FSM) with self-aligning ball bearing supporting structure was designed to accurately control the transmission direction of high-octane laser. First, linear voice coil actuators were selected and SiC mirror, rigid supporting structure, precise grating sensors for measuring mirror position were designed respectively on the basis of the fast-steering mirror working conditions and performing requirements. After finishing accurately manufacturing and assembling of mechanism parts, the servo control system was constituted, and then the designed FSM system was tested by experiments. The results showed that the FSM with self-aligning ball bearing supporting structure has not only great carrying capacity and resonance frequency, but it also has excellent angle stability (the stable precision of mirror is more than 2″). Furthermore, the FSM system has great adaptability to vibrancy, impact and rotation. Therefore, the designed FSM can satisfy application requirements of precise beam control system.

The main drawback of diode laser array is the inhomogeneous intensity distribution in the far field. So the beam shaping technology is very important in the application of laser diode array. This work present a novel beam shaping optical system based on fly’s eye lens. The system can homogenize the diode laser array based on the multi-aperture beam integrating theory. Such beam shaping system was designed by ray tracing method using ZEMAX™ Non-Sequential Components analysis tools. The ray-tracing simulation shows that a 5 × 5 mm² Top-Hat intensity profile was got at a working distance of 40 mm and the homogeneity of the intensity distribution is better than 90%. And it is verified that such beam shaping system is adapted for the aberrations of bars very well by simulation. Based on the design, a relative experimental research on the beam shaping system for 5 bars LD stack is carried out. Through the beam shaping system the laser diode power intensity is improved 4 times, light field distribution nonuniformity is less than 10%, and the system coupling efficiency is more than 80%, which validated the engineering feasibility and applied value of this novel LD array beam shaping system.

Pulse laser micromachining technology, as a branch of laser processing technology, has been widely used in MEMS device processing, aviation, instruments fabrication, circuit board design etc.. In this paper, a novel nanosecond pulse laser micromachining system is presented, which consists of nanosecond pulse LASER, optical path mechanical structure, transmission system, motion control system. Nanosecond pulse UV laser, with 355 nm wavelength and 40ns pulse width, is chosen as the light source. Optical path mechanical structure is designed to get ideal result of laser focusing. Motion control system, combining PMAC card with the PC software, can control the 3-D motion platform and complete microstructure processing. By CCD monitoring system, researchers can get real-time detection on the effect of laser beam focusing and processing process.

The relative position of wafer and mask can be calculated by information of Moiré fringe during alignment, a maskless lithography alignment method based on circular gratings Moiré fringes phase-shifting technique is proposed in this paper. Circular grating Moiré fringes have characteristics of measuring simultaneously angular displacement and line displacement. Location information of wafer in alignment can be real-time reflected in spatial phase of Moiré fringes. A digital micromirror device controlled by a computer is used to generate phase-shifting grating labels, and phase-shifting Moiré fringes will be formed by superposition of phase-shifting grating labels with grating label on the wafer. The position information of wafer can be abstained by phase analysis using Fourier transform method combined with phase-shifting technique，and gives feedback to the displacement stage to realize alignment. The theory basis of this method is emphatically introduced. Also, application of this method in maskless lithography alignment is analyzed in detail. Simulation results show that this method is high in accuracy, simple in operation and simple in algorithm. It provides a feasible method for lithography alignment technique.

For step and scan lithography systems, the synchronization of reticle stage and wafer stage during exposure is one of the most important factors that decides the image quality. In this paper, their principle is analyzed through investigating the structure of step and scan lithography systems. And the coarse and fine laminated model is built. Based on this model, three different kinds of synchronous control structures containing parallel, series and cross-coupled are proposed. Then, the reticle stage is used to compensate the error of the synchronous control system of wafer and reticle stage. Simulation results demonstrate that this control strategy has good synchronization performance, and the synchronous error of wafer stage and reticle stage is less than 0.5nm without disturbance.

Dynamic infrared scene generator is an essential means for testing the performance of infrared imaging systems. DMD(Digital Micromirror Device) is widely adopted as spatial light modulator for the dynamic infrared scene generator. We present a new optical architecture for illumination and projection, in which a relatively large aperture lens both contributing focal power in illumination and projection. At present, the rotation of each micromirror array of DMD is limited to ±12 deg. The narrow tilt angle of micromirror of DMD makes it difficult to separate the incident and the reflected light beams when telecentric architecture is applied. A TIR (total internal reflection) prism is commonly introduced to avoid this interference of illumination system and projection system. In this article, a field lens is introduced to replace the TIR prism to do the separation, in respect that the TIR prism for infrared is not available normally and has a great energy loss during the beams travelling through the prism. The matching of exit pupil of illumination and entrance pupil of projection is a basic requirement for DMD illumination and projection system design. This lens reused structure makes exit pupil of illumination and entrance pupil of projection at infinity from the device surface, since we locate the position of stops of illumination and projection system at the focal plane of the field lens. This architecture with fold mirror added could offer a relatively compact optical mechanic structure.

As a new type of grating, the freestanding blazed transmission grating combines the advantages of traditional transmission gratings (low mass, relaxed alignment and flatness figure insensitivity) with those of reflection gratings (high broadband diffraction efficiency, high spectral resolution). A freestanding blazed transmission grating with period of 1μm was successfully fabricated by holographic lithography and anisotropic wet etching of silicon. The duty cycle is about 0.13. The aspect ratio of a single grating bar is about 77. The thickness is 10μm and the open area fraction is about 58.8%. The size of a single die is 15mm×15mm divided into four 5mm ×5mm windows. The diffraction efficiency of the grating was measured at the National Synchrotron Radiation Laboratory in the wavelength region of 5-50nm. The results show a strong blazing effect in the direction of specular reflection from mirror-like grating sidewalls, as expected.

Nondestructive surface inspection technology is getting mature, nevertheless, there is an urgent requirement for method capable of detection and characterization of the subsurface defects at micron to nanometer scales. In this paper, we propose a method for the detection and characterization of the subsurface defects based on the depth-segmented partial-wave microscopic spectroscopy. By combination of optical coherence tomography with partial-wave microscopic spectroscopy, depth-segmented partial-wave microscopic spectroscopy capable of micro-nano structure detection and characterization at specific depth range is put forward.

A design method of diffractive optical element is presented for converting a single modal Gaussian beam into a flat-top beam in the far field of the source. The design is based on geometrical method and modified Gerchberg-Saxton method. Geometrical method derives from the conservation of energy and the constant optical path length. This method could supply initial phase distribution of the modified Gerchberg-Saxton method. To find the optimization design results, the modified Gerchberg-Saxton method is important to choose the feedback factor to increase the convergent speed. In addition, tolerances and limitations of such elements result in a reduction of the diffraction efficiency and as a result of stray light. Further study indicates that deviation of the laser wavelength, incident beam, and observation plane can greatly influence flat-top beam shaping quality. On the basis of theoretical and experimental results, limitations for the application of diffractive beam shaping elements are investigated.

Aspheric optical surfaces are often tested using computer generated holograms (CGHs). CGHs can generate any desired wavefronts to realize phase compensation. In addition to fabrication errors of CGH, adjustment errors of testing system can seriously affect the precision of aspheric surfaces testing. In order to eliminate adjustment errors of CGH and the tested aspheric, this paper designs a new layout of CGH that has the advantages of high adjustment accuracy and simple experimental operation. What is more, this paper provides a full set of design idea and design process for the engineering application of aspheric surfaces testing. Finally, combined with the current international processing and testing levels, simulation analysis results of all kinds of errors in the aspheric testing system, which shows that this system meets the requirements of high precision aspheric surfaces testing.

Image denoising is the process of getting the location coordinates of the star point. The extent of denoising determines the measurement accuracy of star sensor attitude. As the star sensor accuracy increasing, the need for star chart-depth study of the noise reduction process, thus reducing the false rate of the target extraction. Noise sources are: Star background noise, molecular noise, electronic noise, etc. In order to reduce the noise, analyze noise source and characteristicness; compare three Laplacian noise reduction effect; and put forward the associative templates. The results show that Laplacian typically is unacceptably sensitive to noise, will produce double edges, and is unable to detect edge direction; LOG has a voluminous convolving mask so that the computation is complex; The improved mask has good edge detection and high antinoise performance.

In this paper a new manufacture technology of the micro-lens generated on needing positions is suggested. This technology doesn’t need mould or masks, it generates the micro-lens on the needing positions directly according to needing curve shape. It is a simple and quick laser micro-manufacture technology, which solves the difficulties of high accurate separation the micro-lens from substrate and adhesion the micro-lens to working face coaxially. A microdetector to fluorescence spectrum using the micro-lens generated on needing positions is made. The detector has many advantages, for example high sensitivity and micro volume. It can be inserted in biochip, and it is used in alarm system of harmful microbes in spacecraft also.

In current study we perform molecular dynamics simulations of nanoscratching of amorphous polystyrene. The AIREBO potential is utilized to describe intermolecular and intramolecular interactions in simulated polystyrene system. In addition, the effect of chain length on the deformation behavior of polystyrene chains, force variation, and increment of temperature and potential energy is studied. Our simulations results demonstrate the permanent deformation of polystyrene during nanoscratching is governed by chain sliding and deformation of chain itself, i.e.. change in chain structure and rotation of phenyl group. There is strong chain length dependence of the mobility of the chain, which in turn affects deformation behavior of polystyrene and machining force. The influence of chain mobility on temperature and potential energy variations is also discussed.

Circularly symmetrical phase etched computer-generated hologram (CGH) are widely used to test aspheric surface. In CGH fabrication errors, pattern distortion errors not only strongly affect the test precision but also can’t be facilely eliminated. In order to improve the test accuracy of system, a moiré fringes method is described for testing circularly symmetrical pattern distortion. Compared with the conventional method of using microdensitometer, the new method is more accurate and quicker for measuring the pattern distortion. Then, based on the accurate measurement of CGH pattern distortion, the impact on test accuracy that pattern distortion brings is eliminated with synthetic wavefront error map. Finally, through computer simulating, it is proved that the new method can effectively reduce the impact on test accuracy that pattern distortion brings.

Optical component is the key to large-scale laser device developed by one of its load capacity is directly related to the device output capacity indicators, load capacity depends on many factors. Through the optical components will damage parameters database load capacity factors of various digital, information technology, for the load capacity of optical components to provide a scientific basis for data support; use of business processes and model-driven approach, the establishment of component damage parameter information model and database systems, system application results that meet the injury test optical components business processes and data management requirements of damage parameters, component parameters of flexible, configurable system is simple, easy to use, improve the efficiency of the optical component damage test.

Lithography is one of the most important and complicated key equipments for the Integrated Circuit (IC) manufacture. The ultra-precision stage is the important subsystem of lithography and its motion performance impacts directly on the resolution and throughput of lithography. In this paper, a robust and high response speed control strategy for dual-stage manipulator is presented. The coarse/fine dual-stage uses the linear motor driven coarse (macro) positioning stage and the Lorenz plane motor driven fine (micro) positioning stage. By adopting merits of both coarse and fine actuator, a desirable system having the capacity of large workspace with high resolution of motion is enabled. The feedback controller is constructed so that the fine stage tracks the coarse stage errors. The controller is robustly designed as the master-slave control strategy. In addition, the position decoupling which translates fine stage’s machine position command into its actual position command are discussed and, as a result, the overall coarse/fine dual-stage servo system exhibits robust and high response speed performance. Simulation shows that master-slave controller can much decrease positioning error and improve response speed of the coarse/fine dual-stage system.

With the shortening printing wavelength and increasing numerical aperture of lithographic tool, the depth of focus(DOF) sees a rapidly drop down trend, reach a scale of several hundred nanometers while the repeatable accuracy of focusing and leveling must be one-tenth of DOF, approximately several dozen nanometers. For this feature, this article first introduces several focusing technology, Obtained the advantages and disadvantages of various methods by comparing. Then get the accuracy of dual-grating focusing method through theoretical calculation. And the dual-grating focusing method based on photoelastic modulation is divided into coarse focusing and precise focusing method to analyze, establishing image processing model of coarse focusing and photoelastic modulation model of accurate focusing. Finally, focusing algorithm is simulated with MATLAB. In conclusion dual-grating focusing method shows high precision, high efficiency and non-contact measurement of the focal plane, meeting the demands of focusing in 193nm projection lithography.

Piezoelectric ceramic driving power is one critical technology of achieving the piezoelectric ceramic nano-precision positioning, which has been widely used in precision manufacturing, optical instruments, aerospace and other fields. In this paper, piezoelectric ceramic driving power will be summarized on micro-displacement driving technical development and research. The domestic and overseas piezoelectric-driven ways will be compared and control model algorithms will be discussed. Describe the advantages and disadvantages of piezoelectric ceramic driving power in a different driving and control model, and then show the scope of application of driving power.

In course of developing, testing, launching and working in orbit, Space camera has to undergo the shock of external loads and changing environment. The optical performance of a long focal length space camera is largely determined by external mechanical loads and ambient temperature. The performance of the camera is a result of the interaction between environment factors. The performance of the optical system should be making an accurate forecast when a modern optical instrument is designed. In this paper, the research methods are reviewed firstly. Then the related technologies are described. The analysis methods of environment temperature and structural characteristics effecting space camera imaging performance are also discussed.

In the waveguide grating structures (WGS), strong resonance between the diffraction waves and waveguide modes will result in a narrow peak in the extinction spectrum. In this article, a plane-wave transfer matrix method is used to investigate quantitatively the influence of the perturbation in the structural parameters on the narrow-band optical response of the WGS. These parameters include the modulation depth and the duty cycle of the grating structures, the thickness of the uniform intermediate layer between the waveguide and the grating structures. Numerical results and theoretical analyses indicate that the adjustment of the tuning range of the resonant signals can be realized by optimizing the relevant parameters. For example, the resonant signal shifts to longer wavelengths with increasing the modulation depth or the duty cycle of the grating. The intermediate layer between the grating and waveguide will results in multiple resonant modes in the extinction spectra and all of these signals shift to the longer wavelengths with increasing this extra layer. These results can be used as a guidance for the applications of the WGS and is important for the applications of the WGS or the waveguided metallic grating structures in sensors and optical switch.

For fabricating high-quality mesh pattern in a deep concave spherical substrate by laser direct writing technique, the exposure dose must be kept constant during the whole scanning process. The principle of the equipment for fabricating mesh pattern in a deep concave spherical substrate via laser direct writing technique was introduced. And the formulas that express the mathematical relationships between the dimension of the substrate, parameters of mesh pattern and the scanning velocity have been deduced by analyzing motion state for scanning arbitrary latitude line. And the mathematical model of scanning motion with constant exposure dose was built. Then the servo control system including software and hardware was developed. The scanning angular velocity could be tuned precisely according to line’s latitude by the control system, which could maintain the linear velocity invariantly to keep the exposure dose constant, so the lines’ quality could be improved. Mesh pattern with 500 μm gridding period was written in a deep concave spherical substrate with a rise-span ratio 0.31 utilizing the control algorithm. After development, the lines on the substrate have good uniformity, and there steep and straight side walls parallel to each other, error of linewidth and gridding period is within ±1% and ±5%, respectively.

With the development of Super Large Scale Integration (SLSI) and integrated optics, high-resolution photolithography has become more and more important. Traditional photolithography is limited by the optical diffraction of the system. Recent discovery of extraordinary behaviors of the surface plasmon polaritons suggests a novel method of photolithography beyond the diffraction limit. In this paper, we report on a novel subwavelength nanolithography technique using a surface plasmonic resonant cavity formed by two metallic layers separated by a photoresist layer with two incident beams illuminating from two sides. Finite-difference time-domain (FDTD) simulations show that a two-dimensional (2D) dot array pattern with a period of 70 nm can be obtained using an exposure radiation of 436nm wavelength. It is also found that the period of the 2D dot array is tunable which can be implemented by varying the cavity length.

In this paper, we present a novel photolithographic technique to achieve variable 1D or 2D nanostructural patterns using a fixed 2-D metallic phase mask based on surface plasmonic interference. With different polarizing orientations of the incident light and a diffraction-limited phase mask which is formed by a metallic square array with a large period, surface plasmons (SPs) interferometric parttens with resolutions beyond diffraction limit can be obtained. The effects of different polarizing orientations of the linearly polarized incident light on the generation of uniform nanostructures have been investigated by the finite-difference time-domain (FDTD) method. Numerical simulation results show that 1D and/or 2D tunable nanostructures with resolutions beyond diffraction limit can be obtained by controlling the polarizing orientation of the incident light.

In 45nm technology node and beyond with hyper NA and Off-axis Illumination (OAI) lithography, mask induced polarization effect is remarkable. At this scale, traditional Kirchhoff approximation, in which the masks are considered to be infinitely thin objects, is no longer valid. Rigorous three-dimensional (3D) mask model is required for precise evaluation of mask diffraction. In this paper, a general 3D mask model based on the rigorous coupled-wave analysis (RCWA) is presented, and the change of polarization state as a function of mask and incident light properties is evaluated. The masks considered are the binary chrome mask and 10% Si-Si₃N₄ attenuated phase shifting mask. The results show that the mask induced polarization effects depend on the mask and incident light properties, such as mask material, absorber thickness, mask pitch, feature size, the polarization and incident angle of the light.

The quality of the microfluidic chip will influence the separations, injections, reactions and measurements of samples in the microfluidic system, it is essential to detect the structure such as the width, depth and roughness for evaluating its performance. Aiming at this requirement, digital holography microscope method is developed to achieve the quantitative, non-contact phase imaging with the full field. Firstly, the digital image plane holographic microscopy is designed, and the complex amplitude of the whole wave field is reconstructed by the angular spectrum method. The two-step phase subtraction and surface fitting methods are combined to eliminate the phase aberration, and the unwrapped phase information is extracted using the least-squares phase-unwrapping algorithm. Meanwhile, we acquire the profile parameters of the microchannel using white light interferometer, and the results demonstrate that the digital image plane holographic microscopy is feasible and effective for the profile measurement of microchannels in the microfluidic chip.

To measure the radii of curvature (ROC) for micro-accessories in precision and ultra-precision with high accuracy, the thesis put forward a new technology based on digital images of scanning electron microscope (SEM), in which the contour line of specimen was attained and the ROC was calculated after data fitting. The Canny edge detection and some other image processing techniques were successively adopted to extract the edge profile of single diamond particle. Then a high order polynomial was used in view of the least square law to fit the sampling point coordinates of contour line nonlinearly. Lastly, the ROC could be computed according to the metric ruler of SEM and the proposed formula. The measurement result shows that the deviation between the technology and current methods is no more than 10%, as the magnification rate of SEM, the amount of sampling points on contour line and the order of fitting model are 1200, 80, 20 respectively. Besides, the measurement accuracy can reach a nanometer scale. This research also indicates that it is suitable for the ROC measurement of non-optical small parts or other micro-accessories with high feasibility and application value.

Lithography occupies an important position in the development of integrated circuits. As a core component - the wafer stage is a high accuracy, real-time and large travel control important equipment, which has a significant impact on lithography alignment accuracy and exposure quality. The complexity of the wafer stage control and the real-time feedback of synchronization errors are the practical needs in high quality communication. As a general-purpose communication device—USB in various fields has a wide application, and its reliability has been sufficiently validated. In this paper, USB is used as data transmission device to achieve entire communication process. Grating data in FPGA is processed and transferred into host computer, and then it is used to do error analysis. Meanwhile the feedback of grating data from FPGA is aimed to promote the stage orientation precision. The host computer transfers data and custom command through USB to monitor the state of stage motion and guarantees the high-precision control.

According to the assembly accuracy of fusion ignition targets, the process of the Hohlraum inserted into the TMP (Thermal Mechanical Package) is analyzed, and its tolerance range is determined. Based on the analysis, the scheme of the precision robotic assembly is designed, and its prototype system is developed. The experiment of Hohlraum inserted into the TMP is carried out by the prototype system for the first time. The experiment results verify the feasibility of insertion and offer the needed transformation of the precision robotic system.

In optical trapping, annular beam as a kind of hollow beam is used to increase the axial trapping efficiency as well as the trapping stability. In this paper, a method for producing an annular beam by a system consisting of a single axicon and a pair of lens is proposed. The generated beam was also used as the optical tweezers. We use the geometrical optics to describe the propagation of light in the system. The calculated intensity distribution in three-dimensional space after the system shows a good agreement with the experimental results. The advantages of this method are simplicity of operation, good stability, and high transmittance, having possible applications in fields like optical microscopic, optical manipulation and electronic acceleration, etc.

It is difficult to process quartz to get a large aperture ratio micropore(Φ127μm) by the mechanical tools, but it is possible processed by MEMS technology. The fluorine etching technology is used in experiments. The etching rate of quartz is proportional to the concentration of the HF acid. The etching rate of the mixtures of different proportions of the HF acid (49%) and the NH4F solution (35%) can be acquired, and the etching rate is lower if NH4F solution (35%) replace by the saturated NH4F solution. The experimental results conform to the chemical equation of Judge J S. In the experiment of the micropore etch, the wafers are respectively put in the mixtures of 1:1 and 3:2 ratio of the hydrofluoric acid (49%) and the ammonium fluoride solution (40%), and the morphology of micropore can be observed by the scanning electron microscopy and the confocal microscopy, and then the deepest depth of the micropore is tested by the confocal microscopy, the relationship between etching rate and the proportional of mixed solution can be got.

Using Hartmann-Shack (H-S) wave-front sensor to test lenses with high numerical aperture, the reference spherical wave-front from pinhole is used to calibrate the Hartmann sensor to improve the precision of calibration, but intensity uniformity of the reference spherical wave-front affects the precision of Hartmann sensor’s calibration. Based on the vector diffraction theory, intensity uniformity is calculated with finite-difference time-domain method in case of a converging Gaussian incident visible light on pinhole. In order to proof the correctness of the intensity model of pinhole vector diffraction, experimentation of intensity is performed in visible-light. When the pinhole is the material aluminum with thickness 200nm and pinhole diameter 500nm, the absolute error of intensity uniformity is about 2.57% and 2.31% within 0.75 NA and 0.5 NA of diffracted wave-front by comparing experiment result with simulation result, so the intensity model is accurate.

This paper demonstrates a novel tunable CW THz source design, which can generate a THz wave with frequency from 0.75 THz to 1.75 THz, based on nonlinear laser frequency mixing on a photoconductivity structure. The device consists of a semi-insulating GaAs substrate with silicon nitride antireflective coating, an epitaxially low-temperature-grown In0.52Ga0.48As thin film and an Archimedean spiral metal antenna with two electric contact pads. The Multiphysics software COMSOL was used to simulate the THz source system. Different dimensions of the metal antenna have been modeled. It is shown that when the dimensions of the metal antenna are given as inner radius 15 μm, outer radius 95 μm, spacing between each turn 10 μm, width of each arm 10 μm, and turns number 2, respectively, the spiral antenna’s frequency band is from 0.5 THz to 3.2 THz, which can sufficiently cover the frequency range of a desirable wideband tunable THz source. This paper also presents some related THz radiation simulation results based on the proposed structures.

A novel decoupling method is proposed to tackle the temperature-strain decoupling issue conveniently and economically for distributed fiber temperature and strain sensing systems (DTSS). Because Rayleigh backscattered light is not sensitive to either temperature or strain, a faction of it is taken as a reference light to eliminate the influence from emitting light caused instability and to ameliorate interference factors such as light path’s disturbance in the system. On the other hand, using a RF frequency filter, we were able to distinguish factors from Brillouin backscattered light intensity or its frequency shift on the heterodyne signal. In this paper, the working principles and related experiment results are presented. After calibration, the length of the sensing fiber is 13 km and the spatial resolution is 7 m. Other parameters are anticipated as temperature resolution 1°C, and strain resolution 20 εμ in this system.

A one-step introduction of functional defects into a photonic crystal (PC) is demonstrated. By using a multi-beam phasecontrolled holographic lithography and a diffracting optical element, large area one dimensional (1D) and two dimensional (2D) PCs with periodic waveguide were fabricated. The uniform area is up to 4 mm2, and tens of waveguide have been introduced in the one dimension and two dimension PC structure. This technique gives rise to a substantial reduction of the fabrication complexity and a significant improvement on the accuracy of the functional defects in photonic crystals. This method can also been used to design and fabricate metamaterials.

ZnO has a significant advantage for applications in optical devices. Especially ZnO doped with the rare earths (RE) shows great electronic and optical properties. Based on the density functional theory, using the first-principles calculations method, the crystal structure, electronic structure and optical properties of ZnO doped with various concentrations of Er were investigated. The calculated results show that with the increase of concentrations of Er, the volume of ZnO system is expanded. Simultaneously, the band gap of ZnO with dopant system becomes broad. However, the conductivity of system is enhanced with the decrease of Er concentration. On the other hand, imaginary part of the dielectric function of ZnO doped with Er also changes certainly. A new peak is observed in the low energy region. The results are helpful to gain a systematic understanding of geometrical structures, electrical structures and optical properties of Er-doped ZnO.

In order to develop silicon-based modulation or emission materials, silicones covered by porous silicon (ps) thin film were characterized about terahertz transmission and emission properties from 0.5T to 10T frequency by THz Time Domain spectrograph. Ps films were etched different morphologies through hydrothermal method. According to SEM, micro-surface-structures of these ps films were divided into three types: crater, quasi nano-pillar-array and porous. Terahertz wave transmission amplitude of cater samples was decreased largest and its transmission time delay was the least among the three samples. Compare to cater sample, THz transmission intensity of quasi-nano-pillar sample increased 27%, porous one increased 53%. For time delay, quasi-nano-pillar sample was 0.04ps, porous one was 0.3ps. The first two type's samples had low-pass characteristics and porous samples had cascade band-pass characteristic. There were much absorption peaks in the spectrum of quasi nano-pillar-array sample and porous one. Positions of these peaks had very closed relationship to the micro-surface-structures of ps thin films. In addition, samples could generate μW THz emission at 10THz area after excitation by femtosecond laser. Experiments showed that, both shape and size of these ps films appeared to change and control transmission and emission properties of silicon in 0.5T to 10T, such as transmitted intensity, absorption frequency and emission properties, so nano-micro system porous silicon could be considered as a new material for THz modulation, emission and it could be applied to make integration wide-spectral device.

Piezo-electric actuators with advantage of fast responsiveness, large force output, low power consumption, negligible friction and no backlash are widely used in precision positioning, adaptive optics and vibration conduction. However its inherent hysteresis brings difficulty to high precision positioning. To describe the hysteresis, a mathematical model based on experimental data is used. And the inverse of the model is connected to the piezo-electric actuator as a controller to compensating the hysteresis. In this paper KP operator is used to model the hysteresis of piezo-electric actuators and a numerical algorithm is proposed to compute the inverse. Experiments data of major hysteresis loop and minor loop collected on a nano-positioning stage are used to identify the model Γ based on which the inverse model Γ^-1 is developed. Experiments show that given a voltage series the model Γ can give displacement prediction which has an error of 6% relative to experimental results and Γ^-1 can give voltage prediction with the error of 5% relative to the experimental data.

Fiber Bragg Gratings (FBGs) are candidates for a number of applications in space-borne systems not only owing to their optical functionality but also because they have low mass, small dimensions, and because they are immune to electromagnetic interference. In the case of Earth observation and telecommunication satellites the multiplexing in the optical domain, based on the FBGs, allows a significant reduction of the complexity of on-board electronic systems. Another perspective domain is the fiber sensor systems, such as strain sensors integrated into fuel tanks or structural health monitoring of large space structures. In order to be actually used in space-born systems, FBGs must demonstrate a high stability of their properties over the whole mission time. However, radiation may affect its properties. The possible ways of improving the radiation tolerance of FBGs should be researched. The influence of grating fabrication on radiation sensitivity of the FBGs has been investigated experimentally in this paper. The FBGs were fabricated in different process and GeO₂ concentrations. Pre-irradiation and H₂-loading were applied to change the radiation sensitivity of the FBGs. The FBGs were fabricated in photosensitive fiber and coupling single mode fiber with a GeO₂ concentration in a range from 0.33 to 23 mol%. The lowest Bragg wavelength shift (13 pm) was obtained by a grating written in photosensitive fiber PSF-GeB-125, with pre-irradiation and without H₂-loading for a total dose of about 50 kGy.

To avoid lock-in phenomenon, a rotational oscillation is implemented in mechanically dithered ring laser gyros. This oscillation or dither is typically provided by a dither motor. The dither motor needs to be driven at the resonant frequency, so dither controlling systems must track the resonant frequency of dither motors. In this paper, a frequency track method based on phase sensitive detector technology is put forward and compared with the traditional selfoscillation method in details. In high-low temperature experiments (-40℃ to 60℃), this method and the traditional one are compared. The results show that the new method has the equivalent accuracy as the traditional one. But this method has more compact dimension, and the amplitude evaluation and noise injection are easier.

To improve the optoelectronic tracking ability and rope-hanged platform attitude stability, against the interact effect between rope-hanged platform and optoelectronic system during system tracking process, the optoelectronic system fixed on rope hanged platform simplified dynamic model, according to the system’s Lagrange dynamic model, was established. Backstepping method was employed to design an integrated controller for both optoelectronic system azimuth direction steering and platform attitude stabilizing. To deal with model’s uncertainty and disturbance, a sliding mode controller form based exponential reaching law was adopted to structure the integrated controller. Simulation experiments simulated an optoelectronic system with 600mm caliber telescope, whose inertia fluctuation is 6%. The maximal control moment is 15Nm. And the external disturbance and internal friction effected together. When the line of sight(LOS) azimuth angular input is a step signal with 1rad amplitude, the response’s overshoot is 6%, and the response time is 6.2s, and the steady state error is less than 4×10^-4rad. When the input is a sinusoidal signal of 0.2rad amplitude with 0.0318Hz frequency, the LOS azimuth angular error amplitude is 5. 6×10^-4rad. It is concluded that the controller designed in this article has excellent ability and can ensure the system’s stability.

High temperature pressure pipes were widely used in the chemical, oil companies and power plants, but the pipe burst incidents occurred from time to time, which had caused some damages on people’s lives and property. Thus, in this paper, with the aim to solve this problem, a FBG (FBG: Fiber Bragg Grating) strain gauge structure which consists of three FBGs is designed and fabricated based on the theoretical strain and stress analysis. The strain gauge can be used for the real-time surface strain monitoring of high temperature pressure pipes. In the strain gauge, the elastic hightemperature alloy(10MoWVNb) is chosen as the substrate. The three FBGs with a similar performance are fabricated on the substrate with the high-temperature glue. Among the three FBGs, FBG1 is used for the horizontal strain sensing of high temperature pressure pipes., FBG2 is used for the longitudinal strain of high temperature pressure pipes, and FGB3 is used for temperature compensation. The strain gauge has a feature of high temperature resistance, temperature compensation and two-dimensional strain measurement. The experiment result shows that : the sensing ranges of temperature is 0~300°C, the transverse strain sensitivity is 1.110nm/με, the temperature sensitivity is 0.0213nm/°C; The longitudinal strain sensitivity is 1.104nm/με, the temperature sensitivity is 0.0212nm/°C; the temperature sensitivity is 0.0103nm/°C. Therefore, the strain gauge can meet the needs of the high temperature and pressure pipes.

This paper focuses on a micro-temperature controller which can be used in Antarctic telescope. This controller uses integrated digital temperature sensors and platinum sensors for temperature measurement, and uses single-chip for the system control, and single-bus for signal and data information transmission, which can meet different kinds of heating. With this controller we can solve the problems about temperature of the telescope, such as there are too many temperature test pots on the telescope, the complex control of mirror defroster, and the problem of wiring in such low temperature. In this paper there are only 4 cables needed to make the connection between center computer and power supply. And the remote control and monitoring can be achieved by the center computer. It is very space less, components and energy less, and after series of tests, it can meet the temperature control need of Antarctic telescope.

Infrared thermal wave technology has gained widely adopted as a nondestructive method in many fields, especially in the aerospace, manufacturing industries, etc. In this paper, pulsed thermography method was used to detect a structure with big curvature. The structure, in which there are five pre-designed debonding defects, is steel shell / insulation bonding structure. However, the characteristics of large curvature and complex surface will lead to uneven heat loading and serious non-uniformity of the thermograms. In order to solve the problem, oblique segment detection method was used. Watershed method was adopted to process the acquired thermograms for noise reduction, enhancement and segmentation. Eventually, the size of the defect has been identified. Through the experiment we concluded that, in the same depth, a larger defect is more easily to be identified, and the recognition accuracy is higher; Compared with conventional nondestructive testing methods, infrared thermal wave nondestructive testing is a better curvature tolerant method; For thin specimens, small defects can be well identified; When curvature specimen is in parallel with the pulsed flash tube, there would be a serious reflection phenomenon on the surface. By using the method of surface treatment and oblique segment detection, the results have been greatly improved.

The working principle of LPFG(Long-Period Fiber Grating) is based on coupling effect between propagating core-mode and co-propagating cladding-modes. The effective refractive index of cladding-modes could be obviously influenced by the environmental changes resulting in LPFG more sensitive than FBG (Fiber Bragg Grating) in sensing areas, such as temperature, strain, concentration, bending and etc. LPFG should have more potential in the field of sensors compared with FBG. One of the challenges in using LPFG for environmental sensing is how to interrogate the signal from the LPFG transmission spectrum, due to the large spectral range of the resonant dip. Nowadays the application of LPFG is normally limited in signal interrogation of FBG as optical edge filter. The signal interrogation of LPFG itself needs further research. Presently research on signal interrogation of fiber grating focuses on wavelength interrogation. The aim of wavelength interrogation is to get the wavelength shift caused by environmental change. To solve these problems, a kind of strain sensing interrogation technique for LPFG with low-cost based on tunable FBGs has been developed. Comparing with the method using Fabry-Perot cavity, tunable FBGs can lower the cost with the guarantee of sensing precision. The cost is further lowered without using expensive optical instruments such as optical switch. The problem of temperature cross-sensitivity was solved by using reference gratings. An experiment was performed to demonstrate the interrogation system. And in the experiment, the sensing signal of LPFG applied 0-1300με was successfully interrogated. The results of the interrogation system and OSA are similar.

This paper reports a thick nickel coating for CO₂ laser-induced long- period fiber grating (LPFG) by an electrolesselectroplating method. The thickness of the metal coating is more than 150 micrometer. As well as affording effective protection, the thick metal coating can give the LPFG enough stiffness to overcome its cross-sensitivity between bend and other measurements. In our metallization, electroless Ni-P was deposited on a bare LPFG at 86°C. We observed degradation with broadened spectrum and lessened peak value after the LPFG was electroless plated and was cooled down to room temperature. The degradation may be caused by the new metal coating instead of air and stress. Degradation was also observed in the later electroplating nickel which was induced by the stress. The mechanisms of the stress, such as thermal stress, film growing, hydrogen, and excess energy, were studied. To reduce the degradation, we took optimal plating, such as reducing the cooling speed after electroless plating, higher and stable electroplating temperature, mixing timely and proper electrodes distribution. Under the optimal condition, we got a metallized LPFG whose 3-dB bandwidth was 3.942nm, peak loss was -15.389dB, resonant wavelength was 1547.354nm, and external diameter was 0.425mm. Following temperature sensor experiments showed the metal coated LPFG presented high temperature sensitivity from 10°C to 80°C. Its temperature sensitivity was 44.9 pm/°C, and R-square was 0.9977.

Nonreciprocity is the main contribution of drift error in fiber optic sensors based on Sagnac interferometer, such as the fiber optic gyroscope. When the sensor has to suffer from wide range of temperature, thermal nonreciprocity becomes the most important one required to overcome for it to retain similar performance over all application condition. In this paper, thermal nonreciprocities induced by both pure temperature and thermal stress in the Sagnac interferometer are analyzed respectively. First we deduce the expressions of nonreciprocities in form of phase error of the Sagnac interferometer’s fiber coil, induced by pure temperature and thermal stress respectively. Then a FEA model of such a fiber coil is build up, based on which pure temperature nonreciprocity and thermal stress nonreciprocity are investigated in detail, and their numerical values are also calculated. Finally an experimental system is set up to verify the numerical results and the corresponding errors of the system is measured, which shows good agreement to the simulation value. At the end of this paper, we discuss some methods for reducing the thermal nonreciprocity in the fiber coil, some of which are proposed for the first time.

VO₂ thin films were prepared on soda-lime glass substrates by DC magnetron sputtering at room temperature using vanadium target and post annealing in air. X-ray diffraction and FTIR spectroscopy analyses showed that the films obtained at the optimized parameters have high VO₂ (011) orientation. Both low temperature deposition and post annealing method were beneficial to grow the nano-films with pure VO₂ phase-structure and composition. Metalinsulator transition properties of the VO₂ films in terms of infrared transmittance, transmittance variation and film thickness were investigated under varying annealing temperature. Results showed that infrared transmittance variation and transition temperature of the nano-films were significantly improved and reduced respectively. Therefore, this study was able to develop practical low-cost preparation methods for high-performance intelligent energy-saving thin films.

Different from common liquid crystal displays (LCDs), LCDs in aircraft cockpits have to satisfy some special requirements, including high luminance, high contrast ration, anti-reflection (AR), and electromagnetic compatibility (EMC). Indium-tin oxide (ITO) glasses are usually attached on the top surface of LC cells by optical adhesive for AR and EMC, forming laminated structure. The characteristics of optical adhesive and lamination processing have direct effects on display. This paper creates a finite-element-analysis model of the laminated LC cell with ITO glass. The simulation results show that the stress concentration happens in the case that there are defects (bubbles, cracks, nonuniform thickness) in the optical adhesive when the operation temperature raises to 70º C. Based on the analysis of the stress on the top surface of the LC cell in Y direction, it is found that the location of the stress concentration is just under where the defects exit. The comparison on the stress of 3 possible defects shows that the concentrated stress caused by the cracks are far more large than the stress by the bubbles and nonuniform thickness of optical adhesives, which should try best to avoid.

We present a novel fiber optic flow sensor system by using two fiber Bragg gratings (FBGs) and a cantilever beam structure in this paper. This fiber optic flow sensor uses two FBGs that are bonded on both sides of a cantilever beam to measure the flow rate by monitoring the FBG wavelength changes caused by the bending of the cantilever beam. Cross sensitivity of the temperature dependence of the sensor can be compensated automatically. We fabricate the FBG flow sensor and test it in the laboratory-scaled flow set-up. The testing results demonstrate its high resolution and repeatability for the fluid flow rate measurements. Based on the analysis of test results, the fiber optic flow system will be optimized in the materials of the cantilever beam and the process of sensor fabrication, so as to finally be used in the oil field.