This PDF file contains the front matter associated with SPIE Proceedings Volume 8201, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Detection of pollution, inflammable, explosive gases such as methane, acetylene, carbon monoxide and so on is very important for many areas, such as environmental, mining and petrochemical industry. Intra-cavity gas absorption sensing technique (ICGAST) based on Erbium-doped fiber ring laser (EDFRL) is one of novel methods for trace gas with higher precision. It has attracted considerable attention, and many research institutes focus on it. Instrumentation and optimization of ICGAST was reported in this paper. The system consists of five parts, which are variable gain module, intelligent frequency-selection module, gas cell, DAQ module and computer respectively. Variable gain module and intelligent frequency-selection module are combined to establish the intra-cavity of the ring laser. Gas cell is used as gas sensor. DAQ module is used to realize data acquisition synchronously. And gas demodulation is finished in the computer finally. The system was optimized by adjusting the sequence of the components. Take experimental simulation as an example, the absorptance of gas was increased five times after optimization, and the sensitivity enhancement factor can reach more than twenty. By using Fabry-Perot (F-P) etalon, the absorption wavelength of the detected gas can be obtained, with error less than 20 pm. The spectra of the detected gas can be swept continuously to obtain several absorption lines in one loop. The coefficient of variation (CV) was used to show the repeatability of gas concentration detection. And results of CV value can be less than 0.014.

In the letter, we propose a novel refractometer based on a microstructure fiber (MF) to measure water-samples with a large refractive index. The designed MF is a hollow-core fiber and supports only fundamental mode when the MF is filled with a tested liquid whose refractive index is larger than 1.45. The fundamental mode's effective index of the filled MF is linearly proportional to the refractive index of the liquid. Utilizing this property of the designed MF, the Mach-Zehnder interferometer based sensor is realized. The theoretical result shows that the proposed sensor can works well in the refractive index range of 1.48 to 1.60 and the sensitivity of the proposed refractometer is about 6.41*10^-6.

The ultra-stable laser can be converted to microwave signal with very high fidelity combining with the optical frequency comb, and the ultra-stable microwave down converted can be used as a local oscillator for Cs fountain clocks. To produce such a microwave source, we are developing a 1542 nm laser with a potential relative stability of 10^-15 in one second. In this paper, the ultra-stable laser system with some key parameters and the Pound-Drever-Hall (PDH) locking system are introduced. Furthermore, the method and procedure of coupling the laser into the cavity resonator is described and a coupling efficiency of better than 30% is achieved. Further experiments are carried out and final results will be reported in the future.

The ground deformation observation is the method that estimates the ground deformation according to the displacement change of work spot measured periodically. By using the repeatability of the mechanical transducer and the reliability of the wavelength modulation, the differential fiber Bragg grating settlement gauge reduces availably the disturbance of the artificial causation and the weather. In this scheme, the drive rod converts the displacement of settlement block into the strain of beam, and causes the Bragg wavelength shifts of the sensing gratings mounted on the top and bottom surfaces of the beam, on which the temperature-compensated is achieved by the differential operation of the shifts of Bragg wavelengths. Because the collapse of slope is caused by the cutting slippage as the shearing strength in the soil body of slope exceeded the anti-shearing intensity, the slide prevention pier is the regular retaining structure for treating slope. The differential fiber Bragg grating settlement gauge is developed and fixed on the pier, which converts the settlement of the observation point into the Bragg wavelength shifts of the sensing gratings. Applied in Bai Ni-jing Slope, the measurement precision between the settlement gauges and Wild N3 precise level is 0.03, which is satisfied with the engineering order measure precision 0.05~0.1. By subtract the displacement-induced settlement deviation, the corrected precision between the settlement gauges compensated by Leica J2 theodolite and the precise level is improved to 0.007, which is satisfied with the scientific research order measure precision 0.01~0.05.

We report about fiber Bragg gratings (FBGs) inscribed in two different types of small-core Ge-doped photonic crystal fibers with a UV laser. Sensing applications of the FBGs were systematically investigated by means of demonstrating the responses of Bragg wavelengths to temperature, strain, bending, and transverse-loading. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. Moreover, the bending and transverse-loading properties of the FBGs are sensitive to the fiber orientations. The reasonable analyses for these sensing properties also are presented.

A long period grating (LPG) with agarose gel coating has been developed for relative humidity (RH) monitoring for first time. Increase of RH will result in volume expansion and refractive index increment of the agarose gel cladding coating. Since the LPG is sensitive to applied strain and ambient refractive index, the spectral properties of agerose-gel-coated LPG changes accordingly as the ambient humidity levels ranges from 25% to 95% RH. Both the resonance wavelength and coupling strength turn out particular responses to RH for two different RH ranges (25%-65% RH and 65%-95% RH). The coupling strength decreases within a lower RH range while increases throughout a higher RH range. The resonance wavelength is sensitive to RH only for higher RH levels, and the highest sensitivity reaches 108.67 pm/% RH, sharing a same RH turning point with coupling strength response. From a practical perspective, the proposed RH sensor would find its potential applications in temperature-independent RH sensing and multi-parameter sensing based on wavelength/power hybrid interrogation and even static RH alarm for automatic monitoring of a fixed RH value owing to its non-monotonic RH dependence of the transmission power within the whole tested RH range.

The theory of fiber Brillouin amplifier is investigated by numerical solution combinating interpolation method and Runge-Kutta method. Meanwhile, the most complete characterization and comparison of FBAs for pump power, initial signal power and fiber length is obtained. Through the analysis and comparison, the results show that the amplification efficiency can reach 90% based on the SBS and the most of the power transfer occurs within the first 20% of the fiber length. The output signal power is linear increased with increasing of the initial pump and initial signal, respectively. The high-gain Brillouin amplifier can be obtained when then fiber length is about 26km.

We propose and demonstrate a novel processing cycle for sheet-metal working based on the computerized image processing techniques. The interconnected test system based on the cross network communication enables the effective fabrication cycle that realizes automatic inspection, quick delivery, and cost reduction.

We design two laser ranging instruments (chaotic lidar and chaotic optical time domain reflectometer) using broadband chaotic light for free space and optical fiber. The laser diode with external optical feedback cavity is utilized to realize the chaotic light, and the chaotic light is divided into reference light and probe light by a splitter or an optical coupler. The target position can be achieved from the main peak of the cross-correlation trace, computed by the correlation function between the reference and probe light, and the spatial resolution is independent of the length which is determined by the full width at half maximum of correlation curve. Our instruments can range at least 130 m with 18 cm resolution in free space and 68-km with 6cm resolution in optical fiber.

This paper aims at developing a method to use satellite retrievals aerosol optical thickness (AOT) and filed measured AOT to monitor air particulate pollution. This work is applied during the entire year of 2009, on Wuhan area, central China. The ground level daily mean PM10 mass concentration is measured by tapered element oscillating microbalance. Meanwhile, local daily mean AOT is obtained by using field spectrometer. After that, the correlations between local daily mean AOT and PM10 concentrations are calculated. As the AOT MODIS retrieval AOT has good agreement with field measured ones, the good correlation between MODIS AOT and PM10 mass concentration is demonstrated, and the correlation coefficients range from 0.67 to 0.77. This correlation coefficient has strong season dependence which indicates that the correlation in spring and summer is high, while it is much lower in winter. Then the correlation is improved according to the impact of relative humidity. Based on the good correlation condition, the linear regression analysis is completed with the help of SPSS Statistics.

This paper studied the 3-D reconstructing technology of free curved surface. Initially, it scanned the local model of flight vehicle to use the new digital measuring equipment-laser tracker, got the point clouds of the model. And then, it reconstructed curved surface of the model by using the powerful modeling function of CATIA. Finally, the paper also utilized the units of alignment and data processing to make a relative error analysis of the reconstructed model and point clouds. The experiment conclusion showed that the method of measurement accorded with error requirements, and had the practical value of industrial application and production.

Receiving system for the laser equipment performance testing, although the use of laser simulation testing equipment can overcome the high cost of traditional methods equipment, strict environmental requirements on the venue and other issues. But in the practical application of various laser devices under test, wavelength and frequency are varies. So that laser simulation testing equipment requires a higher degree of comprehensive and intelligence. Therefore, we propose a new comprehensive multi-wavelength laser simulated-testing technology, and study the design and application of comprehensive laser simulated-testing instrument in the test of receiving system of laser equipment. Our design process in these devices there are two technical bottlenecks for us and we propose efficient solutions:(1)Complex structure of the optical system, the volume mass is too large; (2)Different wavelength laser firing unit with low degree of integration and the high cost of processing. The instrument has the advantage, the ability to easily and real-time test different wavelengths and frequency of laser devices to receiving system with a high degree of device comprehensive and low cost.

In order to measure the angle variation property of the mechanical-electrical structure in the system integration measurement and environmental experiments, a laser two-dimensional angle dynamic measurement system using the optical auto-collimation principle is developed, which can achieve the high precise and real-time measurement. The experiments indicate that the angle measurement precision is less than 10 second, the measurement range is within ±0.5 degree and the measurement rate is 1 KHz. The developed system provides a new technique for the high precision and rate measurement of the two-dimensional small angles.

For any tunable diode laser absorption spectroscopy (TDLAS) system, its performance is often degraded by long-term distortion and fluctuations of light intensity. The source of long-term distortion and the corresponding proposal are discussed at first in this paper. It is proved that the long-term distortion of the system is mainly induced by the change of wavelength dependent transfer function. A balanced optical path can be used to reduce it effectively. In order to decrease the disturbance of intensity fluctuation, a novel method for online correction is presented. It is developed according to the linear relation between the peaks of harmonic power spectra and the incident light intensity. It is demonstrated by the experiments and explained as residual sum frequency and difference frequency power of signal and reference after the lock-in amplifier. This method could achieve real-time light intensity correction with only little calculation. By using a 17.5m multi-pass cell, the experiments show that the system can achieve about 20ppmv stability for long-term continual monitoring. Allan variance indicates that the detection limit for short-term measurement is between 0.3ppmv and 1.5ppmv depending on the response time allowed by the instrument.

It is difficult in interferometric metrology to maintain high spatial resolution over a large field of view. In this paper this characteristic is achieved by scanning two focused laser beams over an object surface and a reference mirror surface, respectively, with a rotating mirror, a lens, and a polarization beam splitter. An electric-optic phase modulator generates the phase difference of a sinusoidal waveform of 10 MHz between the two focused beams. Sinusoidal phase-modulating interferometry is used to calculate the phase of the interference signal caused by the two focused beams. The scanning speed of the beams is 20 m/s, and the sampling interval of the interference signal is 1/80 microseconds. The spatial resolution is 2.0 microns over the measurement region of 18.8mm. The measurement results show that the measurement error is less than 5nm.

The wavefront collimation of the optical interferometric systems must be controlled strictly. A scanning cube corner retro-reflector is introduced to divide the wavefront of the interferometer into a series of sub-wavefronts. The tilt angles of all the sub-wavefronts are obtained to reconstruct the tested wavefront thus the collimation test of the wavefront can be realized. The wavefront in the horizontal direction of a 100mm aperture interferometer is tested and reconstructed. The PV and RMS value of the collimated wavefront are 0.629λ and 0.130λ. The effect of system error on the experimental results is analyzed. The experimental results show that this method is of low cost and high accuracy, and is particularly applicable to the collimation test of a large aperture wavefront.

Dispersed Rayleigh Interferometer (DRI) is designed for 3 degree-of-freedom alignment of a grating pair contained in chirped-pulse-amplification laser pulse system. The working Gaussian pulse laser spectrally centered at 1053 nm with an FWHM bandwidth of 5 nm is utilized as the broadband light source. The relationship of DRI interferograms and alignment errors is simulated, based on which the alignment criteria by image processing method are determined. Structural parameters of the DRI are carefully designed according to the simulations. Theoretically, the final coarse measurement range for piston error is 5 mm, with positional sensitivity of 20 nm and angular sensitivity of 8 μrad within a fine measurement range of 500 μm.

Based on the ray matrix theory, we theoretically analyzed the property of the optical axis perturbation versus L/r (L means the total length of the resonator and r is the radius of curvature of the mirrors in the resonator) in the nonplanar ring resonators by using statistical method for the first time as we know in this paper. The results show that the root mean square of the optical axis tilt change evidently versus L/r while the optical axis decentration have a subtle change versus L/r for the case that the mirror misalignments are confined in a certain scope and chosen arbitrarily. From the perspective of optical axis perturbation, we can find the configuration parameters with which the optical axis perturbation in the resonator responds violently to the mirror radial displacement or misalignment angle. These interesting findings are important for cavity design, improvement, and alignment of nonplanar ring resonators.

In this paper, a novel method based on simulated annealing algorithm (SAA) was described for polarization errors suppression in distributed perturbation sensor based on dual Mach-Zehnder interferometer(DMZI). It was shown both theoretically and experimentally that the inaccuracy (±100m) of the position of the perturbation is caused by polarization-induced phase errors. By applying high speed polarization controller based on SAA, the polarization-induced phase errors were suppressed and the accuracy of the position of the perturbation is up to±10m.

A sensor which exploits dual-interferometric technique for absolute displacement measurement is proposed. The interferometer performing the measurement task operates low coherent-optical interferometry and highly coherent-optical interferometry simultaneously. The absolute measurement range, which is determined by the bandwidth of the Bragg wavelength reflected by the Fiber Bragg Grating (FBG) in the sensor, is larger than 6mm. And the measurement resolution, which is determined by the highly coherent-optical interferometry, is less than 1nm.

The characterization of spray behavior especially the droplets parameters are very important for many industrial applications. In this paper, the droplets parameters of a flat fan water spray were measured using a new developed global rainbow refractometry. the global rainbow mechanism of spray is studied in detail. The effects of discrete parameter, distribution function, mean diameter and disperse coefficient on global rainbow of spray are concerned. a new rainbow parameter inversion algorithm of particles is proposed. This algorithm can inverse both particle diameter distribution and refractive index simultaneously, without pre-knowledge of droplets diameter distribution function and range. The algorithm removes the noised using empirical mode decomposition (EMD) method, and inverses the data based on regularized NNLS and regularization method. The experimental measurements are performed on a flat fan air-blast atomizer spray, and the droplets size distribution and the refractive index have been measured under five different gasliquid ratio conditions.

Optical pickup head is composed by many optical elements, and the relative position of the optical elements should be adjusted precisely and be bonded carefully. Different bonding process may lead to different influence of the optical pickup head's function; worse bonding process even may destroy the optical pickup head. In order to ensure the product quality of optical pickup head we develop one kind of method to study the influence of bonding process and introduce one kind of solution. We use 24 pieces of optical pickup heads to measure the objective lens' focus voltage and analyze the statistical distribution. After 2 hours' saving under 70°C and 2 hours' saving under normal temperature we measure the objective lens' focus voltage and analyze the statistical distribution again. Through comparing the above two groups' data we can know the variation after 2 hours' saving under 70°C and 2 hours' saving under normal temperature. Through changing the primary position of the objective lens and measuring and comparing again and again we can control all optical pickup heads' objective lens' position in the range we wanted. Once we find objective lens' ideal primary position and bonding process we can fix these conditions and apply them to manufacture. It suggests that such kind of method is useful and necessary for optical pickup head's industrial production.

The traditional detection of minimum resolvable temperature difference (MRTD) is mostly under laboratory conditions, and the results are obtained by the tester's subjective interpretation. Because of its large and complex system Structure, it is very difficult to apply in the field on-line detection. In this paper a set of field on-line detection system of infrared thermal imager is designed, single blackbody control technology is adopted to simulate temperature difference of four bars target and environment, and a coaxial Cassegrain collimator is used to simulate infinity target, through this way volume and quality of the detecting equipment is effectively reduced. Instead of human eyes we use CCD to capture the thermal imager's imaging result, an effective filtering method which combine linear filter and nonlinear filter is adopted to reduce noise and enhance the captured image, then four bars target area is accurately extracted as the target area, to reduce noise a rectangular area which just contains four bars target is extracted as the background area. Using relationship between temperature difference of four bars target and environment and gray level difference in corresponding infrared image, the parameter MRTD of the infrared thermal imager can be calculated, the experiments show that the result is in good agreement with the result of the human eye observation. The detection system has a simple structure, small size, low cost, high level of automation, etc. It can realize the on-line automatic detection of MRTD under field conditions better.

In view of the difficulties of testing the range accuracy of infrared phase range finder under field conditions, this paper establishes a simulated testing model. This model receives the infrared wave emitted by the phase range finder, and then makes spectrum analysis on the sampled received wave to obtain its initial phase. Therefore the initial phase of the local oscillation source in the phase range finder can be estimated. According to the preset simulated range value the initial phase of the simulated echo can be calculated and set. By examining the response after the phase range finder receiving the simulated echo, it is possible to judge whether its range accuracy is up to the technical specification. This paper presents functional simulation experiments, and the results confirm the feasibility of the simulated testing system model.

Cube Mapping is a popular and promising environment mapping technology in which six cubic images containing the information of entire environment are used to enhance the reality of the virtual object in the Augmented Reality system. In this paper, a new method is proposed, which generate the six cubic images in real time from a pre-process unplanned image sequence gotten by a calibrated camera. As a part of system initialization, a series of unplanned image sequences were recorded, as well as the camera extrinsic-parameter of each image. While every virtual object is rendered, several images are chosen according to the camera's position and attitude information to build an environment sphere model whose center is same as the virtual object's. Each of the select images is filled to corresponding area of the sphere model's surface due to its orientation and the upper direction of the camera. After the surface of the sphere is full of filling, the model is constructed to reflect the all surrounding scene like a mirrored sphere. According to the equirectangular projection algorithm, the surface of the sphere model with longitude and latitude coordinate system can be unfold to rectangular image which is called equirectangular panoramic image. Then the six cubic images can be segmented from the equirectangular panoramic image by a special algorithm.

We used terahertz time-domain spectroscopy (THz-TDS) technology to measure liquid bactericide quintozene and obtained its absorbance spectrum in THz region. Meanwhile, its theoretical spectrum was obtained by software package Gaussian 03. Experimental characteristic absorption peak in 1.84 THz was agreement with theoretical peak in 1.81THz, which was caused by flexural vibration of the benzene ring. Quantitative experiments were carried out on quintozene MtBE solutions in the concentration range of 30-100 μg/ml. We analyze the relationship with simple linear regression (SLR) method between the amplitude value and concentration of the solutions in 0.1-1.05 THz region, which included the THz pulse peaks and the first order value of the linear fit of absorbance spectrum. The overall results indicate that the simple linear regression is an effective method for the quantitative analysis of quintozene solutions.

Optical incremental encoders are used widely in rotating machinery to obtain the motion information, such as CNC machine tools and robotics. The motion information can be employed to investigate the dynamic properties for the rotating machinery. For example, the instantaneous angular speed (IAS) obtained via this way contains a lot of useful information related to the operating condition and health state of the machine, which can be used for condition monitoring and fault diagnosis. The measurement scheme for IAS by using optical incremental encoder is investigated. Subsequently, the relationship between estimation error of IAS and some parameters are discussed, such as the sampling frequency, the count number of encoder and the interpolation selection of the sinusoid output signal. Finally, an IAS estimation approach based on polynomial fitting is given. At the same time, the relationship between IAS estimation accuracy and the order of polynomial, the number of fitting points is also investigated. The effectiveness of this approach is verified by using some simulations and experiments on a CNC machine tool. The vibration source is determined successfully by using the proposed method.

High-precision measurement for fluorescence quantum efficiency of solid materials has been a very cumbersome and complex process. In recent years, though many scholars have done a lot of studies, the relative and simplified measurement are mainly been emphasised on, and it is very difficult to obtain the accurate measurement uncertainty. Refering to NRC, on the basis of the little appropriate transformation on commercial instruments, this paper introduces the absolute quantum efficiency measurement for solid materials, based on double monochromator method. Currently, the measuring wavelength covers 250-800nm, the uncertainty of quantum efficiency is about 5%(k=2) .

A distributed optical fiber grating wavelength interrogator based on fiber Fabry Perot tunable filter(FFP-TF) was proposed, which could measure dynamic strain or vibration of multi-sensing fiber gratings in one optical fiber by time division way. The wavelength demodulated mathematical model was built, the formulas of system output voltage and sensitivity were deduced and the method of finding static operating point was determined. The wavelength drifting characteristic of FFP-TF was discussed when the center wavelength of FFP-TF was set on the static operating point. A wavelength locking method was proposed by introducing a high-frequency driving voltage signal. A demodulated system was established based on Labview and its demodulated wavelength dynamic range is 290pm in theory. In experiment, by digital filtering applied to the system output data, 100Hz and 250Hz vibration signals were measured. The experiment results proved the feasibility of the demodulated method.

According to technical requirements and the structure characteristics of long-focal-length optical system, the paper analyzes the advantages and shortcomings of reflective system and refractive system in details. By the aberration theory and ZEMAX optical design software, a long-focal-length space optical system which is characterized by the catadioptric configuration,with the spectrum band 500~ 800 nm is designed. And evaluations show that the image quality is close to the diffraction limit. After being manufactured, the optical transfer function (simplified MTF) of long-focal-length lens is tested, and it shows that the best focal planes of spectrum 500nm~800nm, 550 nm, 650nm are not in the same position and deviate greatly, which is chromatic aberration. Whereas, after remeasuring the long-focal-length lens, it is found that the MTF values of the three wavebands can meet the qualification requirements simultaneously if we defocus 57.7μm from the best focal plane of spectrum 500nm~800nm. Finally, the cause of chromatic aberration phenomenon in the measurement of catadioptric optical system is deeply discussed at the first time based on the structure characteristics of optical system, then the improvement is achieved correspondingly and the results show as below: the full-aperture spherochromatic aberration of improved optical system is reduced from 0.45μm to 0.25μm, and its MTF values are up to 0.6 plus. The technical requirements of high-precision, small size, light weight, good image quality are fulfilled.

A new apparatus for continuous measuring the falling velocity of wind-dispersal seeds is presented in this paper. The key unit of this apparatus is the photo-detectors installed on the ends of a vertical tube. The photodetector is composed of a LED and a photo-sensor. The LED light goes through a horizontal slit to from a flat light plane, which be received by the photo-sensors on the opposite side. When a plant seed falls down and passes through the flat light plane, a pulse signal will be detected by the photo-sensor. The average falling velocity of the seed is calculated according to the falling time and the distance from the starting point to the testing point. By using several tubes and photo-detectors, the apparatus can continuously measure the velocity of a seed falling down to different height. This apparatus avoids the affect of the static electricity and airflow to the seeds.

The Lunar Laser Ranging (LLR) System is a part of the Lunar Exploration. It is used to detect the photons reflected by the retroreflector on the moon, and to accurately calculate range from the earth to the moon at a certain time, so as to improve the pointing precision of the telescope and correct the lunar orbit. The data is indispensable for other research about the moon. This paper not only analyses the main factors (the performance of chosen telescope, the power of laser used in LLR, the capability of detector) in affecting the detection capability of the Lunar Laser Ranging system, but also analyses the whole detection capability under the situation of all parts of an apparatus that could be attainable around the international areas. At last, the economic, feasible, with high performance-to-price ratio supporting programs are presented.

Strapdown inertial navigation technology, which is widely used in aerospace, is a navigation technology in which the gyros sensor and accelerometers sensor are rigidly attached to the body of the object. This article describes an application of strapdown inertial navigation technology in indoor dynamic positioning system. The hardware design of the node include the master controller, data collection, sensors, antenna and related peripheral circuit. Positioning algorithm, data acquisition and transmission are done by software programming based on the hardware circuit. The strapdown inertial navigation composed of the hardware and the software could calculate the position of the object. Simulation software(matlab) is used to confirm the correctness of the positioning algorithm which is implemented by software programming in the system. The system uses the wireless sensor network to expand the range of the positioning. The system of which the information transmission is reliable and the mobility is strongly can satisfy the requirements of the emergency.

Changchun Station completed Kilo Hertz SLR and daylight tracking system upgrade the year before last. Routine operation has been over 2 years since July, 2009. We have obtained about 16 thousand passes in total, including more than 40 hundred passes in daylight. The main upgrades of Kilo Hertz SLR and daylight tracking in Changchun observatory includes new Kilo Hertz Laser, Event timer, Ranging control system, Spectrum filter, Higher pointing stability and optic route adjust etc. these contain related research contents such as optics, machinery, electron and automatic control and so on.

Rotary position sensors are widely used in many applications that require precise shaft unlimited rotation: including control systems, robotics and AR (Augmented Reality) systems. However, traditional data acquisition system is often a PC-based (Personal Computer-based) one with complex structures and complicated electrical connections, which means that the system has limited application for its size as well as its poor portability. That is a main drawback, especially for AR system in which the user is supposed to walk freely. In this paper, a novel portable data acquisition system (PDAS) based on USB interface technology with a succinct hardware structure is proposed. Implemented on an 8051-based microcontroller AT89C5131, the proposed system can receive signal from optical encoder, decode the signal and transfer the data to the computer through USB interface. The experimental results show that this system can provide the possibility to realize portable and improve performance of AR, which demonstrate the efficiency of the proposed system.

The optical performance is severely degraded by surface scattering effects, especially for short wavelength imaging systems. Surface scattering effects is one of important factors degrading imaging performance. Study of non-intuitive surface scatter effects resulting from practical optical fabrication tolerances is a necessary work for optical performance evaluation of high resolution imaging systems. In this paper, surface scattering numerical model of grazing incidence imaging systems is discussed at first. Then Soft X-ray optical scattering distribution is measured by a soft X-ray reflectometer, for different sample mirrors, wavelength and grazing angle. By dealing with experimental data, different factors effects on surface scattering, such as glancing angle, wavelength and roughness is computed and analysised. It is indicated that the scattering increases as the grazing angle increases, surface roughness increases and the wavelength decreases, and optical system performance decreases.

Due to the special properties of cylindrical lens, the testing of it is more difficult than that of spherical lens. In this paper, a new method for testing the radius of infrared cylindrical lens is introduced, and the error analysis is discussed. The method is presented based on the real ray tracing method. The parallel beam incidents on the cylindrical lens and the width of the beam reflected from the cylindrical lens is measured by CCD. The width of the rays is related to the radius, so the radius of the infrared cylindrical lens can be calculated.

The quantitative rainbow schlieren technique was applied to measure density grads and density in flow flied widely. The experiment took the axis-symmetry unexpended supersonic free jet as a object, used the typical "Z" schlieren system and replaced the edge with rainbow filter. Different rainbow filter was designed to study the sensitivity and validity in the quantitative measurement. While schlieren measurements were compared with numerical value using FLUENT. Good agreement between the measurement and numerical value was achieved on the unexpended-supersonic jet.

Abstract: the orbit determination exclusively using single station SLR(Satellite Laser Ranging) data is unviable, which limits the application of SLR technology in the observation of space debris. The paper puts forward that the orbit determination can be achieved through using SLR data assisted by the proper weighted telescope pointing data of the SLR system. To process the SLR data of AJISAI satellite by the above method, the data consist of the orbital arcs with 3-day spans, the precision of orbit determination is about 10 cm. Discussion shows that space debris orbit determination by the above method is also feasible.

Raman spectrometer has been widely used as an identification tool for analyzing material structure and composition in many fields. However, Raman scattering echo signal is very weak, about dozens of photons at most in one laser plus signal. Therefore, it is a great challenge to design a Raman spectrum data acquisition system which could accurately receive the weak echo signal. The system designed in this paper receives optical signals with the principle of photon counter and could detect single photon. The whole system consists of a photoelectric conversion module H7421-40 and a photo counting card including a field programmable gate array (FPGA) chip and a PCI9054 chip. The module H7421-40 including a PMT, an amplifier and a discriminator has high sensitivity on wavelength from 300nm to 720nm. The Center Wavelength is 580nm which is close to the excitation wavelength (532nm), QE 40% at peak wavelength, Count Sensitivity is 7.8*10⁵(S^-1PW^-1) and Count Linearity is 1.5MHZ. In FPGA chip, the functions are divided into three parts: parameter setting module, controlling module, data collection and storage module. All the commands, parameters and data are transmitted between FPGA and computer by PCI9054 chip through the PCI interface. The result of experiment shows that the Raman spectrum data acquisition system is reasonable and efficient. There are three primary advantages of the data acquisition system: the first one is the high sensitivity with single photon detection capability; the second one is the high integrated level which means all the operation could be done by the photo counting card; and the last one is the high expansion ability because of the smart reconfigurability of FPGA chip.

Spot-image based aberration retrieval method determines aberration directly from optical system's spot image with no extra hardware. In this paper, we propose a new spot-image based aberration retrieval method using the parametric model of point spread function (PSF). This model is built with scalar diffraction integral and its Bessel series representation. In this model, complex amplitude of PSF is represented by linear combination of function series with Zernike coefficients of wave aberration at pupil plane. With this PSF model, intensity distribution of spot image can be calculated without fast Fourier transform or numerical integration. Conjugate gradient method is used in our aberration retrieval routine and the proposed method is simulated with MATLAB. The retrieval results are satisfying for both noise-free and noisy star image.

A continuous emission monitoring system (CEMS) using hot wet extractive method based on differential optical absorption spectroscopy (DOAS) is designed. The developed system is applied to retrieving the concentration of SO₂ and NOx in flue gas on-site. The flue gas is carried along a heated sample line into the sample pool at a constant temperature above the dew point. In this case, the adverse impact of water vapor on measurement accuracy is reduced greatly, and the on-line calibration is implemented. And then the flue gas is discharged from the sample pool after the measuring process is complete. The on-site applicability of the system is enhanced by using Programmable Logic Controller (PLC) to control each valve in the system during the measuring and on-line calibration process. The concentration retrieving method used in the system is based on the partial least squares (PLS) regression nonlinear method. The relationship between the known concentration and the differential absorption feature gathered by the PLS nonlinear method can be figured out after the on-line calibration process. Then the concentration measurement of SO₂ and NOx can be easily implemented according to the definite relationship. The concentration retrieving method can identify the information and noise effectively, which improves the measuring accuracy of the system. SO₂ with four different concentrations are measured by the system under laboratory conditions. The results proved that the full-scale error of this system is less than 2%FS.

Online inspection of glass containers is important to guarantee the high quality production, safe use and effective recovery, so high precision and low cost online detection system has important practical value. The system introduced in this paper consists of LED linear array as the light source, a linear CCD as the detector, and a dual core processor with ARM and DSP as well. The self rotating stage for glass bottles and the digital image process technology enable this system to acquire the complete data and improve the traditional detection method. As a result, a detection speed over 100 bottles per minute, and a precision over 99.99% were achieved with the relatively simple structure and low cost.

Digital data acquisition system is a key part of the whole lidar system, which plays an important role in ensuring detecting accuracy and is the emphasis of this paper. Lidar system could detect both Raman and Mie backscattering signal simultaneously. A digital data acquisition system is designed to capture the signal in this paper. A FPGA chip is used as an essential part in the digital data acquisition system to control time sequence and process capturing data. Then the data is transmitted into the computer through a USB interface, and displayed in the real-time by dedicated software. Three channels of the system can be programmed separately to measure Mie and Raman scattering signal simultaneously within a single measurement. Moreover, acquisition resolution can be chosen among 15m, 30m and 45m. Meanwhile, some other detecting parameters can also be specified, such as height layers and so on. In the aspect of communicating with PC, a Cypress USB CY7C68013A chip is used in this design. The interface is set to work in Slave FIFO mode in the USB firmware, by which FPGA can control USB easily, just like controlling a normal external FIFO. Usually, USB interface can transmit the data faster and more convenient than other PC interfaces. Results of experiments demonstrate that the digital data acquisition system works correctly and accurately.

During KHz daylight tracking, the KHz laser beam is high repetition frequency and low pulse energy. And it is difficult to maintain receive and transmit path parallel. This paper introduces a new method of daylight visibility of KHz laser beam real-time. It resolved the problem of too much background noise at daylight and used the high sensitivity CCD to require the daylight KHz laser beam imaging real-time. It applied the spectrum filtering technology, exposure superposition, changing exposure time and image processing technology in the experiment. The clear backscatter image of KHz laser beam had been required real-time. It has important significance to enhance daylight KHz satellite laser ranging (SLR) system in detecting ability.

In SLR system, the pointing precision of telescope significantly influences the tracking efficiency. Compensating the pointing precision commonly uses mathematical models to fit the error of the telescope pointing which are restricted by the quantity and visibility of the stars conditions. To avoid these limitations, this paper proposes a new method to utilize SLR tracking data to fit the deviation between the observed data and predictions. It takes the data density into consideration, and makes use of the residual analysis to aid the model-fitting. We will utilize the observed data of Changchun station to calibrate the pointing precision of our telescope in time.

The wearing degree of the wheel set is one of the main factors that influence the safety and stability of running train. Measurement of wheel set wear has significant importance to railway safety. An automatic measurement method for geometrical parameters of wheel set based on optoelectronic technique was proposed. In the method, linear structured laser light was projected on the wheel tread surface. The geometrical parameters can be deduced from the profile image. An online image acquisition system was designed based on asynchronous reset of CCD. The entire time sequence of asynchronous reset was designed. The image was acquired only when wheel moved into the designed position. Image acquisition was fulfilled by hardware interrupt mode. Quantitative relation between position accuracy and speed, timedelay error, CCD resolution and imaging region was deuced. Relation between moving blur and speed, exposure time was also decided. The measuring system was installed along the straight railway section. When the wheel set was running in a limited speed, the devices placed alone railway line can measure the geometrical parameters automatically. Position accuracy achieved 1.1mm when moving speed reached 2km/h and moving blur was limited in less than one pixel size while exposure time set to be 1/5550s. The image definition can meet the demand of real and online measurement.

People with neuromuscular disorders are difficult to communicate with the outside world. It is very important to the clinician and the patient's family that how to distinguish vegetative state (VS) and minimally conscious state (MCS) for a disorders of consciousness (DOC) patient. If a patient is diagnosed with VS, this means that the hope of recovery is greatly reduced, thus leading to the family to abandon the treatment. Brain-computer interface (BCI) is aiming to help those people by analyzing patients' electroencephalogram (EEG). This paper focus on analyzing the corresponding activated regions of the brain when a subject responses "yes" or "no" to an auditory stimuli question. When the brain concentrates, the phase of the related area will become orderly from desultorily. So in this paper we analyzed EEG from the angle of phase. Seven healthy subjects volunteered to participate in the experiment. A total of 84 groups of repeatability stimulation test were done. Firstly, the frequency is fragmented by using wavelet method. Secondly, the phase of EEG is extracted by Hilbert. At last, we obtained approximate entropy and information entropy of each frequency band of EEG. The results show that brain areas are activated of the central area when people say "yes", and the areas are activated of the central area and temporal when people say "no". This conclusion is corresponding to magnetic resonance imaging technology. This study provides the theory basis and the algorithm design basis for designing BCI equipment for people with neuromuscular disorders.

A novel absolute distance measurement method based on the optical frequency comb of the Ti:sapphire femtosecond laser was presented. In the spectrally-resolved interferometry (SRI), all modes interference signals of the optical frequency comb was obtained by the femtosecond light pulses traveling along different optical path between the reference and measurement arms. The interference intensity in the frequency domain was inverse Fourier-transformed into the time domain, and the phase peak was isolated by use of an appropriate Hamming window, then the phase difference which was caused by the distance was resolved in the frequency domain. The simulation results indicated that this algorithm could satisfy the demand of the small scale profile measurement with the non-ambiguity range of millimeter level, and the resolution of nanometer level. Furthermore, combined with the conventional phase ranging method, the max measurement distance of our method can be extended to several dozen meters.

Broadband UV radiometers are widely used for measuring UV irradiance or radiant exposure in various areas of health, industry, and science, such as in weather aging of materials, semiconductor lithography, non-destructive testing, UV curing, catalytic process, environmental monitoring, atmospheric research, water purification, medical diagnostics and therapy, space-based astrophysical observations and other applications. The accuracy of measurement is influenced by many factors such as the characteristics of the radiometer, operating conditions, environmental conditions and the UV sources to be measured. Due to the lack of spectral resolving power, significant measurement errors may occur if the radiometer has poor quality. Five different calibration and traceability methods of UV radiometers were realized and analyzed at National Institute of Metrology (NIM), including absolute spectral irradiance method based on standard lamps, absolute spectral power responsivity method of detectors, absolute thermoelectric radiometer method, electrically calibrated pyroelectric radiometer method and method of comparing with the standard radiometer. The above methods were used to realize the irradiance responsivity of a broadband UVA meter independently. Compared to absolute spectral irradiance method based on standard lamps, relative deviation of these traceability methods are 0%, 0.18%, 2.50%, -3.04% and 4.11% respectively. Absolute spectral power responsivity method of detectors is adopted by the most national metrology institute to realize UV irradiance responsivity. The deviation of absolute thermoelectric radiometer method results from poor signal-to-noise of the combination of radiation source and a UV filter, near to the sensitivity limit of the absolute radiometer. The largest deviation of method of comparing with the standard radiometer comes from different response wavelength, different receiving area between the standard radiometer and the test radiometer. Spectral irradiance method based on standard lamps is the principal traceability method of NIM tracing to the national spectral irradiance primary standard directly. This method was proved by international comparison of "Irradiance Responsivity of UVA Detectors APMP PR-S1". The comparison results showed that the consistency between the NIMs' value and the international reference one is the best among the seven participants. On the basis of the above theories and methods, the uncertainty of broadband ultraviolet irradiance standard under the defined conditions was cut down to 2.0% (k=1) from 10% (k=1).

Liquid prism is a sort of prism composed of liquid. It can create adaptive systems by taking advantage of the unique properties of liquids. The liquid prism can be applied in optical communication, biochemistry and medicine, optical imaging system, etc.. Here the liquid prism is applied in refractometers to analyze the refractive index, density, concentration and dispersion of liquid. Comparing with Abb refractometer, this refractometer uses a liquid prism instead of several solid prisms, thus its weight and cost are reduced. In addition, the measuring range of the refractive index may be 1.15~2 and excels Abb refractometer (n:1.33~1.70) to meet measurement of some new liquid materials such as ionic liquids, liquid crystals, and so on. Moreover, it can avoid the measuring error resulting from liquid uniformly coating on the prism and leaking light in Abbe refractometer. So it takes on broad market foreground.

At present, Multi-spectral pyrometer (MSP) used in high-temperature measurement has already had high resolution and high signal to noise ratio. However, the non-source temperature (higher than 3000°C) calibration falls far behind the development of MSP and has already seriously hindered the precision and application range of the pyrometer. In order to break through the limitation of calibration of non-source temperature, a new calibration method has been put forward in this paper. The temperature-voltage (T-U) model is formed based on power function where output voltage U of the MSP is derived from its corresponding known temperature point. Based on the model, Derivative least square method is used to obtain the parameters of the model to realize the non-source temperature calibration. Both theoretical and experimental data have proved the efficiency and precision of the calibration method. In addition, within the spectral range of high-temperature measurement pyrometer (0.4um~1.1um), the theoretical aberration within 1800°C extrapolation range is less than 13.54°C.

Work-pieces registration is a crucial item in flexible manufacture assembly. In order to finish work-pieces registration, a method is proposed based on affine invariant. After the CAD model data and actual measurement data of a work-piece are acquired, the method consists of the following five steps: sampling point clouds data, extracting characteristic four-points set, searching characteristic congruent four-points set, computing transformation congruent matrix and the last, further precise point clouds data registration. Point clouds data of CAD and measuring model are sampled respectively through calculating the curvature of the two sets of data and selecting the obvious curvature points as their reduced characteristic points. Based on this, the characteristic four-points set from the reduced ones of CAD model and the corresponding matching congruent four-points set of the measuring model are extracted according to RANSAC algorithm. The rotation matrix R and translation vector T of any two matching four-points are then calculated through the algorithm of quaternion. After that, the measuring model is rotated and translated and then compared with the CAD model data, the most congruent transformation matrix is selected as the coarse registration result. Furthermore, Iterative Closest Point (ICP) algorithm is applied to the congruent transformation to improve registration precision. The experiment shows that the run time of the algorithm is 129.56s and mean-error of point-to-point distance is 0.062mm when accessing measuring model data more than 80000 points. Compared with the traditional curvature registration, the experiment also shows that the algorithm is more efficient and robust when the volume of point clouds data is larger.

A vibration-displacement measurement system by tracking the phase variation of an optical fiber Michelson interferometer with an electronic feedback loop is presented. The measurement system includes an electronic feedback loop which is used to track the phase variation induced by the measured vibration-displacement and provides a sense of direction of the displacement simultaneously. The measurement system is designed to be capable of measuring vibration-displacement with frequencies up to 200Hz and the measurement resolution can reach 13nm.

Camera calibration is a necessary step in 3D vision measurement. Classic technique uses a volume calibration pattern with control points distributing in a 3D space, which is expensive to be made and difficult to be used everywhere. Zhang proposed a planar pattern based calibration method, making the calibration process accessed to almost everyone. Nowadays, consume camera with zoom lens is populated and always used for measurement. Such a camera has the advantage to zoom the lens to get a maximum resolution images for objects with different sizes at an adequate distance. The size of Zhang's planar pattern is fixed, not suitable for a zoom lens. In this paper, a multiple sheets planar pattern is used to deal with this situation. The calibration pattern is made of 1-4 sheets of planar pattern distinguished with coded markers, and the total size .can be modified by changing the distance between the planar sheets or the number of sheets to suit for different lens setting. Such composed calibration pattern is easy used both for laboratory and industrial situation. In the calibration process, one sheet of the planar pattern is first used to get an initial calibration according Zhang's method, and also the initial coordinates of all the control points in the sheets of planar patterns. Then a bundle adjustment algorithm is carried out incorporating of the planar constraints and distance constraints in the planar patterns to obtain a set of precision parameters. Some examples are presented to show the effeteness of the method.

The infrared thermal imaging systems are widely used for distinguishing target radiation temperature difference and they can also be used to measure the absolute temperature of the target. There may be great difference between the true value and the measurement results in the actual application of the infrared thermal imaging systems, just because of the unstable condition and the lack of compensation of the imager's own heat radiation. In order to obtain the accurate temperature of the target in some special conditions, such as aircraft internal and pilotless platform, we present a stationary infrared thermal imaging system to gather the goal gradation images and a method to compensate the influence of the imager's own heat radiation and the unstable condition. In radiation calibration experiment, we establish corresponding relationships between the gradation difference and the temperature difference by using a goal blackbody and a cooperation calibration blackbody between 0°C and 150°C. We also analysis the relationships mentioned above under the normal temperature and the high temperature separately. The results show that the proposed method may be useful in increasing the temperature measurement precision.

In this paper, a novel intensity modulated strain sensor is proposed and demonstrated by employing a solid core photonic crystal fiber (PCF)-based cascaded Mach-Zehnder interferometer, in which a middle collapsed region is introduced at the middle point of the PCF to improve the sensitivity of the sensor. Experimental results show that this proposed structure has high temperature stability without any compensation process and a high sensitivity of 15.5 dBm/mε over range of 1.3 mε can be achieved.

In order to measurement of Triglycerides in human serum with reagent-less using near-infrared (NIR) spectroscopy. Interval partial least square (iPLS) was proposed as an effective variable selection approach for multivariate calibration. For this purpose, an independent sample set was employed to evaluate the prediction ability of the resulting model. The spectrum was split into different interval. Then, the informative region of Triglycerides (1654-1746nm), in which the PLS model has a low RMSEP with 0.157mmol/L and a high R with 0.967, is selected with 18 intervals. The results show that the informative region of Triglycerides can be obtained by iPLS and applied to design the simpler reagent-less NIR instruments for inexpensive Triglycerides measurement in future.

A new approach based on laser differential confocal technique is potential to achieve high accuracy in radius of curvature (ROC) measurement. It utilizes two digital microscopes with virtual pinholes on the CCD detectors to precisely locate the cat's-eye and the confocal positions, which can enhance the focus-identification resolution. An instrumental system was established and experimental research was carried out to determine how error sources contribute to the uncertainty of ROC measurement, such as optical axis misalignment, dead path of the interferometer, surface figure error of tested lenses and temperature fluctuation, etc. Suggestions were also proposed on how these factors could be avoided or suppressed. The system performance was tested by employing four pairs of template lenses with a serial of ROC values. The relative expanded uncertainty was analyzed and calculated based on theoretical analysis and experimental determination, which was smaller than 2x10^-5 (k=2). The results were supported by comparison measurement between the differential confocal radius measurement (DCRM) system and an ultra-high accuracy three-dimensional profilometer, showing good consistency. It demonstrated that the DCRM system was capable of high-accuracy ROC measurement.

A simultaneous phase-shifting Fizeau interferometer based on birefringent thin film and Dammann grating is presented. The circularly polarized laser is reflected by the reference plate to form the reference beam and transmitted from the reference plate with the birefringent thin film to form the test beam. The test beam is reflected by the test surface and transmitted from the reference plate again. Its rotation direction is reversed. The orthogonally circularly polarized reference and test beams are obtained. A Dammann grating and an analyzer array are used to achieve simultaneous phase shift. This interferometer can reduce the effect of residual birefringence to increases the measurement accuracy. It is strictly common-path simultaneous phase-shifting Fizeau interferometer with simple structure and easy operation. In experiments, a wedge plate was measured and its simultaneous phase-shifting interferograms were obtained. With these results, the feasibility of the interferometer is verified.

Optical observation for space objects plays more and more important roles in space objects surveillance. Based on the analysis of the motion characteristics of space objects, this study proposes a detection algorithm for space objects, which is based on the operation of frame-to-frame difference, auto threshold segmentation and morphological filtering (Top-Hat operator). According to the slowly varying characteristics of star background, the detection algorithm utilizes a method named frame-to-frame difference to eliminate stars, and detects space objects through auto threshold segmentation and morphological filtering. The algorithm is used easily to process the sequence of star images that are focused in the real condition, and detects space objects reliably in complicated back-ground of star background, which is also convenient to further target recognition and track.

This paper mainly discusses the measuring and traceable methods of spectral irradiance and ultraviolet irradiance in order to advance the accuracy of the two quantities. The contents include: 1.The working principal of the primary standard apparatus of spectral irradiance and spectral radiance and the value transferring methods of spectral irradiance. 2. The traceable methods of ultraviolet irradiance to spectral irradiance primary standard apparatus. 3. Introduce the international comparison of spectral irradiance and the comparison of irradiance responsivity of UV detectors. 4. The influence factors that decrees measuring accuracy of UV radiometer and the capability evaluated methods. We put forward a fitting function of spectral irradiance of standard lamp and an optimizing method for parameters. The relative deviation of the fitting function is acceptable comparing to the uncertainty of national primary standard of spectral irradiance lamp. We also defined evaluated capabilities of UV radiometers to reflect the instrument condition and promote measuring accuracy.

The routine spectral calibration is time-consuming and is difficult to use in the field. In this paper, we present a new rapid spectral calibration method based on the holmium oxide panel which has rich of absorbed feature. The ratio of the Spectalon panel signals to the holmium oxide panel signals can be used to calibrate the imaging spectrometer. The spectral resolution of the spectrometer and the wavelength position on the detector array are determined by curve fitting method including Gaussian response model setting and spectral convoluting. The iteration strategy and Pearson coefficient are mix used to confirm the correlation or similarity between the measured and modeled spectral curve. Spectral calibration experiment shows that new method base on the absorbed feature panel can fulfill the quick, accurate and repeatable spectral calibrating requirement.

Wavelength calibration is important for monochromator and spectrograph before accurate application. In the case of a Czerny-Turner double monochromator, work have been down to find out the relationship between slit widths and wavelength error. We do wavelength calibration in different widths of entrance and exit slits, then get wavelength error. The result shows that different widths of entrance slit and exit slit lead to different wavelength error, and wavelength error can be presented as a function of wavelength and slit widths through curve fitting. Thus, correction can be done by solving this function before accurate measurement.

In this paper, one approach of angle measurement of optical wedge used dual-frequency laser interferometer is referred. The asymmetry of the optical corner cubes in reflector housing is analyzed which has a notable effect on the uncertainty of the measurement result. The asymmetry is constituted by two components: ▵h, the height difference between optical corner cubes, and ▵α, the non-parallelism between two front surfaces of optical corner cubes. At last the influence of this error is obtained, and a precision compensation model for angle measurement is established. Keywords: dual-frequency laser interference, sinusoidal measurement angle, optical corner cube, asymmetry

In this letter, a simple but novel temperature sensor based on an alcohol-filled photonic crystal fiber-long period grating (PCF-LPG) is proposed and studied theoretically. For the sensing principle, a section of alcohol-filled PCF-LPG works as a sensor head. As temperature changes, effective indices of the core mode and the cladding mode change obviously because of the high temperature sensitivity of the filled alcohol so that the difference of effective indices of the core mode and the cladding mode is highly affected by temperature. Therefore, the resonant wavelength which arises from light coupling from the fundamental mode to the forward-propagating cladding modes is very sensitive to temperature due to the mode couplings. By monitoring the output resonant wavelength, we can realize the detection of temperature change. Simulation analysis predicts the sensor has high temperature sensitivity, which reaches up to 8.5 nm/°C as the period of the grating is 650 μm.

Pesticide residues on the fruit skin are measured by terahertz time-domain spectroscopy (THz-TDS) in 0.2-1.3THz. Pesticide is mainly residues for fruit, which threatens health of human, so the research about the fruit residues is absolutely important. In the experiment, a kind of pesticide carbendazim, orange, and the mixture of them are measured by THz-TDS, and then calculate absorption spectrums through Fourier transform and Fresnel formula. Experiment results indicate that THz-TDS is an effective tool for the measurement of pesticide residues on the fruit skin.

Various methods for surface form measurement of aspheric and complex optics exist at present. Each method is just suitable for several limited optic surface form measurement. Hartmann measurement is a method that reconstructs the surface form of a test mirror from form slope. It gives quantitative evaluation of a test mirror in a short time. Compared with interferometry, it has advantages such as relatively simple setup, good anti-disturbance property and low cost. However, it is difficult for conventional Hartmann and Shack-Hartmann methods to increase their measurement dynamic range and resolution simultaneously, and they can not be used to measure steep aspheric surface form. A novel method named inverse Hartmann surface form measurement based on spherical coordinates is presented. The method increases the measurement dynamic range and resolution simultaneously. It reduces the measured ray slope, increases the measurement range, and its accuracy of form error is higher than that in rectangular coordinates. It can be applied in online optic product evaluation rapidly and accurately with low cost.

With the explosive growth in the solar industry, it has intensified the need for test and measurement solutions that can quickly and accurately collected characteristics of solar cells and modules. A low-cost out-door solar cell in-line measurement is presented. It provides distributed working parameters collecting for solar cells in each node. And a Zigbee wireless network is imbedded for communicating between measuring node, central station and host computer. The measuring nodes collect working parameters of solar cell, such as short circuit current, open circuit voltage, max power point, shunt/series resistance and so on. In each node, 3-4 solar cells can be measured simultaneously. A Microchip PIC16F690 MCU is employed for I-V curve controlling and measuring by adjusting internal programmable voltage reference. The collected data is sent to central station by Zigbee wireless network. Solar illumination amplitude and ambient temperature are measured in central station, and data from measuring node is forward to host computer by central station too. Host computer get related data and compute fill factor and other important parameters of solar cells in long-term.

The paper describes a fiber sensor for the evaluation of static axis strain and dynamic vibration. A section of high birefringence polarization maintaining fiber (Hi-Bi PMF) is incorporated in a Sagnac fiber loop as the sensing element. The static axis strain measurement is realized by analyzing the attenuation peak wavelength shifts and the strain sensitivity of 1.09 pm/μs is achieved. Using the power intensity demodulation method, the experimental results of dynamic acoustic vibration measurement show that it can detect the acoustic vibrations over the frequency range of 50Hz to 22 kHz.

In this paper, a two locking lasers BOTDR (Brillouin optical time domain reflectometry) system is demonstrated. Two narrow linewidth DFB lasers are used as the light sources. Their frequencies are locked with a frequency difference of about 11 GHz, which can greatly improve the measurement accuracy and system stability. At a 5-km standard single-mode fiber, distributed temperature measurements can be achieved in lab with a spatial resolution of 10m and a temperature resolution of 2°C.

Although 3D scanning system is used more and more broadly in many fields, such computer animate, computer aided design, digital museums, and so on, a convenient scanning device is expansive for most people to afford. In another hand, imaging devices are becoming cheaper, a stereo vision system with two video cameras cost little. In this paper, a hand held laser scanning system is design based on stereo vision principle. The two video cameras are fixed tighter, and are all calibrated in advance. The scanned object attached with some coded markers is in front of the stereo system, and can be changed its position and direction freely upon the need of scanning. When scanning, the operator swept a line laser source, and projected it on the object. At the same time, the stereo vision system captured the projected lines, and reconstructed their 3D shapes. The code markers are used to translate the coordinate system between scanned points under different view. Two methods are used to get more accurate results. One is to use NURBS curves to interpolate the sections of the laser lines to obtain accurate central points, and a thin plate spline is used to approximate the central points, and so, an exact laser central line is got, which guards an accurate correspondence between tow cameras. Another way is to incorporate the constraint of laser swept plane on the reconstructed 3D curves by a PCA (Principle Component Analysis) algorithm, and more accurate results are obtained. Some examples are given to verify the system.

Spectral irradiance scale of 250nm-400nm has been realized with the temperature of blackbody traced back to the eutectic fixed-points blackbody. Since the ITS-90 can only be extended to 2473 K and spectral irradiance of 250 nm-400nm requests that the blackbody be operated around 3000 K. The temperature determination of blackbody is calculated using the ratio of spectra radiance at working temperature and a temperature no more than 2473 K. In the experiment, a pyrometer is calibrated by the Pt-C and Re-C eutectic fixed-points blackbody. Accordingly, the measuring scope of the pyrometer can be extends to 2747 K, which is more close to the working temperature. On the other hand, high temperature blackbody BB3500M is first used as the primary standard of spectral irradiance at the National Institute of Metrology (NIM).

Because of the global characteristic of the Fourier transform method for fringe pattern analysis, it has been extensively developed and widely used in optical metrology. Many other works were published afterward; however, the spatial spectrum characteristic of the Fourier transform method has not been fully and systematically investigated. The spatial spectrum characteristic and its relationship with factors such as the quantization of grey levels, random noise, and spatial carrier frequency are discussed. The results indicate that, the maximum bandwidth can be measured by the Fourier transform method is close to Nyquist sampling theorem. That provides a theoretical quantitative basis for the study of extending the measurement range of the Fourier transform method, also builds the relationship between the spatial frequency can be measured and the resolution of interferogram detector.

We designed and built a measuring system to detect a very small optical rotation. The total measuring system consists of a laser, a Faraday modulator, a photo-detector, and a lock-in amplifier. To test the sensitivity of the system, we built another system to generate the small polarization rotation angle. The rotation-generating system includes a dense coil around a magneto-optic crystal, a power amplifier working at modulation frequency about 1 kHz. The rotationgenerating system can drive probe beam polarization by 2°due to the Faraday effect under 0-2 kHz modulation frequency. We monitor the frequency and amplitude of the modulating signal by observing the second harmonic signal received by the photo-detector. Some factors which influence the detection system have been analyzed experimentally to found the best working setup of the system. Recently we can detect an angle of magnitude at 10^-6rad and the SNR of the output of the lock-in amplifier is above 331.The resolution of the angle detection is better than 10^-7rad.

Using laser interference structure light for profilometry is a rapid, non-contact, full-field profile and high accuracy measuring method.And it has been a promising technique in complicated geometrical shape measurement. In this paper, a fast and cost-effective measurement method of coplanarity inspection of ball grid array (BGA) solder balls is proposed. Laser interference structure light can be obtained by using the principle of shearing interferometry. The collimated and beam expanded laser produced interference fringe by the high reflection rate optical flat. After laser interference fringe project on the surface of object and the structured light would modulated. The light signal pass through the image optical grabber and captured by the CCD image sensor. The height of each point on object can be demodulated by the imaging processing software.This method to construct the measurement appliance for coplanarity inspection of ball grid array (BGA) chip solder ball. Experiments have shown that the coplanarity measurement of BGA solder balls is very efficient and effective with the measurement. The measurement accuracy achieve micrometer level. The processing time of the measurement accuracy is less than 3s on a personal computer. This measurement appliance could completely meet the demand of measure.

With the high-speed development of the social economy, the requirements of the positioning precision and response speed of product on the production line become higher and higher. A new type of photoelectricity automatic positioning system is developed, which consists of vision sensor charge coupled device (CCD), digital image processing and stepper motor controller. They form a closed loop control system, which captures the images by the optical system, achieves photoelectric signal conversion by data image processing and controls the movements of worktable along the X and Y directions by stepper motors. As a result, it achieves fast automatic positioning and compensates the systematic errors effectively, which improves the positioning precision dramatically. In the photoelectric on-line of detecting throttle position sensor resistor, as an example of design, the photoelectric positioning system proves the correctness of the novel photoelectricity automatic positioning system. The positioning time of the system is 0.7s and the positioning precision of the system is 0.35mm, which get ideal results. The experiment of the application has proved that the new type of photoelectric automatic positioning system can be applied in the correlative production line, which has vital significance to improve the accuracy of product processing, reduce the processing time, and increase economic efficiency.

In spectral extinction particle sizing technique, the particle size distribution (PSD) can be retrieved based on the measurement of extinction values at multiple wavelengths. If the measurement is performed at wavelengths within only a narrow spectral range, the accuracy and the antinoise ability of retrieval results will be affected to some degree. In this paper, the retrieval of PSD at multiple wavelengths in the ultraviolet-visible-infrared spectral region is proposed. The extinction efficiency calculated by the Mie theory with different wavelengths is studied, and then the retrieval of PSD in multispectral region is performed. Simulation tests both in the dependent model and in the independent model indicate that the retrieval results in the multispectral region are more stable and accurate than that of only in the visible spectrum region. The retrieval results are satisfactory in the multispectral region with the presence of 5% random noise for unimodal distribution and 3% random noise for bimodal distribution.

Two configurations of orthogonal double-pulse laser-induced breakdown spectroscopy (DP-LIBS) and their corresponding signal enhancement mechanisms were investigated in this paper. For pre-ablation DP-LIBS configuration, the first laser was input in parallel to the sample surface while the second laser was perpendicularly input onto the sample surface. For reheating DP-LIBS configuration, the first laser was perpendicularly input onto the sample surface and the second laser was input in parallel to the sample surface. The signal intensities were enhanced using both orthogonal DP-LIBS configurations compared to single laser pulse LIBS. The differences of physical mechanisms involved for both schemes were analyzed using time-resolved spectroscopic technique. Continuous spectrum intensity was reduced using pre-ablation DP-LIBS excitation while it was increased with reheating DP-LIBS excitation. Nine consecutive intensity measurements were performed. Fifteen spectral lines were investigated. The average relative standard deviation of fifteen lines for pre-ablation, reheating DP-LIBS and single pulse LIBS was 5.83%, 1.69% and 4.82%, respectively. It was demonstrated that signal repeatability of reheating configuration was better than that of pre-ablation configuration. A correlation between the enhancements of emission line intensities and their excitation energy levels was established for reheating and pre-ablation double-pulse approach. It was found that reheating configuration showed better improvement in sensitivity at high excitation energy levels compared with pre-ablation configuration.

In this paper, ultrashort, unipolar electric-field (terahertz) pulses have been used to coherently control population transfer between Rydberg states in lithium atom. Our numerical results show that populations of lithium atoms can be driven to lower or higher n levels with a train of half-cycle pulses, and the the transition rate is sensitive to the static-electric-field strength, the main laser frequency, the optical pulse profile, and the chirp of the laser pulse. If the paramerters of the half-cycle pulses is optimized appropriately, the population can be transferred to the target state completely.

The housing and the camera of video security system are usually manufactured by different companies. During the combining use of camera and housing the main attention points are size, strength, power cord and video cable connecting method and their output channel; the optical matching is less considered and correspondingly poor image output occurs frequently. For improving the image output of video security system it is necessary to study the optical matching between the housing and the camera. VSS camera SCC-C6435 is one kind of indoor camera. SHG-222 is one kind of outdoor housing. The core of camera SCC-C6435 and the cover of SHG-222 are used to combine a new outdoor camera. But after this combination is finished the final image output is not good in some directions. Through measuring and analyzing we can know that the rotating center of SCC-C6435 lens does not coincide with the center of the cover of SHG-222, which is the basic reason of poor image output. After adjusting SHG-222 housing's inner structure accurately and combining them again, we can obtain perfect image output from the newly combined outdoor camera. After considering the optical matching between the housing and the camera we can improve the combined camera's image output greatly. It suggests that during combining one housing and one camera into one new camera with new function the optical matching is one important factor, and optical matching should be added as one important factor during housing design and camera design.

Solar simulators are widely used for indoor measurement of current-voltage (I-V) characteristics as well as irradiance exposure tests of terrestrial photovoltaic (PV) devices. The influence of solar simulator's performance, commonly including spectral mismatch and irradiance uniformity/temporal stability, can never be ignored, especially in the case of I-V characteristics measurement. Herein, we present an integrated system for solar simulator's performance calibration according to IEC 60904-9, which proposed requirements and defined classifications for solar simulators, with items of spectral mismatch compared with AM 1.5 reference solar spectral irradiance (AM 1.5 G), non-uniformity and temporal instability of irradiance. This integrated system is composed of two major departments, i) a calibrated optic fiber spectrometer for spectral mismatch characteristic, ii) data acquisition equipments for detecting irradiance uniformity/temporal stability and calibrating Isc/Voc measurements. It is applicable to various kinds of solar simulators and portable to satisfy the requirements of on-site calibration for solar simulator users.