Contents
2014
Volume: 34 Issue 8
52 Article(s)
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[in Chinese]
Influences Analysis of the Spectral Filter Transmission on the Performance of High-Spectral-Resolution Lidar
Cheng Zhongtao, Liu Dong, Luo Jing, Yang Yongying, Wang Zhifei, Zhou Yudi, Huang Hanlu, and Shen Yibing
Influences of transmission parameters of the spectral filter on the retrieval accuracy for atmospheric aerosol optical properties in high-spectral-resolution lidar (HSRL) are studied. The theoretical analysis model for retrieval error estimation related to the spectral transmission parameters is established based on a Influences of transmission parameters of the spectral filter on the retrieval accuracy for atmospheric aerosol optical properties in high-spectral-resolution lidar (HSRL) are studied. The theoretical analysis model for retrieval error estimation related to the spectral transmission parameters is established based on a general three-channel HSRL configuration and the correctness of this error analytical model is validated by Monte Carlo (MC) simulations. The model and the MC simulation results indicate that the larger the molecular transmittance and the spectral discrimination ratio (SDR) of the filter are, the larger the HSRL accuracy is. Moreover, SDR dominates the retrieval accuracy at low altitudes while the molecular transmittance attaches more influences to the retrieval accuracy at high altitudes. These results are expected to be adaptable to many HSRLs which have the similar multi-channel layout thus can provide certain guidelines to the choosing or designing of the filter..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 801003 (2014)
Atmospheric Optics and Oceanic Optics
Research on Radiation Characteristic of the Multi-Azimuth/Multi-Waveband Earth Limb Ultraviolet Imager
Yang Xiaohu, Wang Shurong, and Huang Yu
Considering the design feature and the difficulty in radiation calibration of the multi-azimuth/multi-waveband earth limb ultraviolet (UV) imager, a method which firstly calibrated the segmented field and then integrated the data has been proposed. With a radiated comparison between the whole field and the segmented fiConsidering the design feature and the difficulty in radiation calibration of the multi-azimuth/multi-waveband earth limb ultraviolet (UV) imager, a method which firstly calibrated the segmented field and then integrated the data has been proposed. With a radiated comparison between the whole field and the segmented field, the output of detector shows a consistence within 1% measurement reproducibility error of the instrument, which returns back to prove the calibration method feasibility. The combined standard uncertainty of the three 290 nm, 310 nm and 355 nm UV bands is 3.93%, 3.90% and 3.84% respectively, which conforms the 3%~5% range of radiation calibration uncertainty of the UV sensors presently. With the successful accomplishment of the segmented field method for the limb UV imager, radiation calibration for greater field or more complicated sensors has been made available..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 801001 (2014)
Model-Based Sensorless Adaptive Optics System
Yang Huizhen, Wu Jian, and Gong Chenglong
A closed-loop control algorithm for sensorless adaptive optics system is proposed based on a relationship where the second moments of the wavefront gradients are approximately proportional to the modified far-field intensity distribution. An adaptive optics system simulation platform is established with a 61-element deA closed-loop control algorithm for sensorless adaptive optics system is proposed based on a relationship where the second moments of the wavefront gradients are approximately proportional to the modified far-field intensity distribution. An adaptive optics system simulation platform is established with a 61-element deformable mirror and a CCD imaging device. The convergence rate,the correction capability and the adaptability of the adaptive optics system are investigated through correcting wavefront aberrations under different strengths of turbulence. The results show that the model-based sensorless adaptive optics system can converge rapidly and obtain correction capability closing to the ideal correction of deformable mirror. The system only needs N+1 photodetector measurements when N order aberrations are corrected and the number of times of measuring far-field intensity is greatly reduced in comparison with existing control algorithms for sensorless adaptive optics system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 801002 (2014)
Error Analysis of Differential Image Motion Lidar
Guo Jie, Sun Dongsong, Qiang Xiwen, Xia Haiyun, Shu Zhifeng, Han Yuli, Zhao Ruocan, and Shangguan Mingjia
Differential image motion lidar is used to measure profiles of atmospheric turbulence. A formula is deduced to quantify the error of differential image motion variance, which provides the basis of qualitative analysis and improvement of system performance. With reasonable arrangement of distance resolution and time resDifferential image motion lidar is used to measure profiles of atmospheric turbulence. A formula is deduced to quantify the error of differential image motion variance, which provides the basis of qualitative analysis and improvement of system performance. With reasonable arrangement of distance resolution and time resolution, the best measurement results can be obtained. According to analysis, two mainly error sources are the errors from centroid position of image and statistical uncertainty of finite sample. The simulation results show that statistical error is the dominant factor at lower altitude, while centroid calculation error plays an increasingly important role with the increasing of distance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 801004 (2014)
Correction Method of Atmospheric Scattering Effect through Optical Path in CO2 Retrieval
Jiang Xinhua, Wang Xianhua, Ye Hanhan, Wei Qiuye, Li Zhiwei, and Bu Tingting
CO2 as the most important greenhouse gas effecting climate change, inversion accuracy within 1% is essential requirement in climate research. One of key points to improve CO2 retrieval precision is account for atmospheric scattering in inversion processing. The spectral range of greenhouse gas monitoring satellite geneCO2 as the most important greenhouse gas effecting climate change, inversion accuracy within 1% is essential requirement in climate research. One of key points to improve CO2 retrieval precision is account for atmospheric scattering in inversion processing. The spectral range of greenhouse gas monitoring satellite generally is narrow to achieve excellent spectral resolution. High spectral resolution has high sensitivity in CO2 concentration changing, however, traditional differential optical absorption spectroscopy (DOAS) methods are hard to assure accuracy in scattering atmosphere. Aim to meet inversion algorithm development, the influence of scattering in CO2 retrieval from path length is studied, compared with traditional DOAS method in desert and meadow. Result indicates that path length method can improve retrieval accuracy and obtain precision close to 1%, and correlation and dispersion of inversion results also can achieve improvement. It is implied that path length method is capable of reducing the impact due to atmospheric scattering in CO2 retrieval..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 801005 (2014)
Research of Spatial Heterodyne Spectroscopy for Atmospheric CO2 Remote Sensing with High Precision
Wei Qiuye, Wang Xianhua, Ye Hanhan, Li Zhiwei, Jiang Xinhua, and Bu Tingting
Considered the rigorous requirement on satellite measurement technology for achieving high precision retrieval of atmospheric CO2, compared with dispersive spectroscopy and interferometric spectroscopy, a novel technology as spatial heterodyne spectroscopy is introduced. According to the requirements on sensor aboard oConsidered the rigorous requirement on satellite measurement technology for achieving high precision retrieval of atmospheric CO2, compared with dispersive spectroscopy and interferometric spectroscopy, a novel technology as spatial heterodyne spectroscopy is introduced. According to the requirements on sensor aboard on satellite, measurement principle and instrument structure are introduced in detail, which exhibits the superiority of this technology as the ability of achieving ultrahigh spectral resolution and high signal to noise ratio, and the key technical advantages of small volume, light mass and low power. Based on these, atmospheric CO2 measurement experiments are carried out using spatial heterodyne spectroscopy (SHS) prototype developed by our institute. The results show that the measurements can satisfy the atmospheric CO2 retrieval, and the consistency of experiment results with greenhouse gases observing Satellite (GOSAT) CO2 is verified that spatial heterodyne spectroscopy has the ability of measuring atmospheric CO2 from space..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 801006 (2014)
Detectors
Optimization for Spatial Resolution and Count Rate of a Far Ultraviolet Photon-Counting Imaging Detector Based on Induced Charge Position-Sensitive Anode
Ni Qiliang
A new prototype of two-dimensional photon-counting imaging detector with induced charge WSA anode in far ultraviolet (FUV) region has been developed based on the FUV imaging spectrometer′s requirements on high output count rate and spatial resolution. The detector is mainly composed of a CsI Chevron microchannel plate A new prototype of two-dimensional photon-counting imaging detector with induced charge WSA anode in far ultraviolet (FUV) region has been developed based on the FUV imaging spectrometer′s requirements on high output count rate and spatial resolution. The detector is mainly composed of a CsI Chevron microchannel plate (MCP) stacks operating in pulse-counting mode, induced-charge wedge-strip position-sensitive anode (WSA) and correlative analog and data processing circuit. A three electrode induced-charge WSA anode with 48 mm diameter active area is designed and fabricated, and front-end analog and data collection circuit are also been developed. The space resolution for induced-charge WSA anode depends on the signal-to-noise ratio (SNR) of front-end analog circuit, while the SNR is relative to the shaping time of shaping amplifier. The longer is the shaping time, the higher is the SNR, and the lower is the maximum output rate of the front-end analog circuit. Both resolution and maximum count rate are measured for different shaping time such as 0.25, 0.5, 1, 2 and 4 μs. The measured results show that the resolution is between 4 lp/mm and 9 lp/mm, and maximum output rate is between 11 kcounts/s and 105 kcounts/s. The shaping amplifier with 0.5 μs shaping time can only completely satisfy the requirement of FUV imaging spectrometer on the spatial resolution and maximum output rate..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 804001 (2014)
Diffraction and Gratings
Design of Parallel Flat-Field Gratings in Soft X-Ray Region
Wang Qingbo, Liu Zhengkun, Chen Huoyao, Wang Yu, and Fu Shaojun
In order to broaden the wavelength range of flat-field holographic concave grating (FHCG), the optimization method of parallel flat-field holographic concave gratings (PFHCGs) is proposed. Two flat-field gratings working in different wavebands, one for 2~5 nm and the other for 5~30 nm, are designed on the same substratIn order to broaden the wavelength range of flat-field holographic concave grating (FHCG), the optimization method of parallel flat-field holographic concave gratings (PFHCGs) is proposed. Two flat-field gratings working in different wavebands, one for 2~5 nm and the other for 5~30 nm, are designed on the same substrate based on genetic algorithm, and the two gratings can work simultaneously because of the same working structure. Theoretical spectral resolution of PFHCGs is studied via ray-tracing method, which is pretty the same as that of existing commercial FHCG. Based on the optical path function theory, the recording optical path of PFHCGs is given. The results demonstrate the line density deviation is less than ±1 line/mm between theoretical value and optimization value. Simulation results show that the waveband of HPFCGs is broaden and the resolution is also ensured, so it is suitable for recording wider waveband of soft X-ray..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 805001 (2014)
Effects of Substrate Position on Laser-Focused Cr Atom Deposition
Zhang Baowu, Zhang Wentao, Wang Daodang, and Yu Guiying
In order to study the effect of substrate position on laser-focused Cr atom deposition, the simulations of optical potential of Gaussian laser standing wave, atomic trajectories and deposited lines are performed based on the perspective of atomic trajectory with different substrate positions in the focusing laser. EffeIn order to study the effect of substrate position on laser-focused Cr atom deposition, the simulations of optical potential of Gaussian laser standing wave, atomic trajectories and deposited lines are performed based on the perspective of atomic trajectory with different substrate positions in the focusing laser. Effects on the above three aspects are fully indicated by substrate position. In spite of diffraction by substrate, the optimal substrate position occurs when substrate surface coincides with the laser axis. At the optimal position, with diffractive laser, deposited lines have full width at half maximum (FWHM) 0.96 times and the center peak value 1.03 times of that deposited by non-diffractive laser. Further more, in spite of diffraction by substrate, the deposited lines along y direction perpendicular to the laser axis have monotone decreasing center peak values and monotone increasing FWHM with different values of y..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 805002 (2014)
Fiber Optics and Optical Communications
Priority Based Resource Reservation Algorithm in Wavelength Division Multiplexing Networks
Tian Xiangxuan, Yang Jungang, Niu Junyong, Du Jia, and Liu Gujing
The priority based source and destination initial reservation protocol (PSDIRP) is put forward in wavelength division multiplexing, which is aimed at solving the optical resource reservation for multiple connection requests arriving at the same time. The source-destination initialized reservation protocol is proposed tThe priority based source and destination initial reservation protocol (PSDIRP) is put forward in wavelength division multiplexing, which is aimed at solving the optical resource reservation for multiple connection requests arriving at the same time. The source-destination initialized reservation protocol is proposed to improve the reservation efficiency. The least utilization rate of wavelengths by the Markov model to determine the available resource factors of multiple requests is got. The algorithm sets the priority and the wavelength assignment model combining with the connection requests′ characteristics, such as total load factor (TLF), through the way of combination of serial control and parallel control. From the simulation, it is can concluded that the algorithm has a better performance in the increase of the resource reservation ratio and the optical network resource utilization rate comparing with the traditional algorithms..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 806001 (2014)
Implementation Method of a Frequency-Doubling Optoelectronic Oscillator
Liu Jingxian, Zhou Tao, Zhong Xin, and Li Wenliang
A frequency-doubling optoelectronic oscillator using the nonlinear effect of the electro-optical modulator is proposed. By introducing a frequency divider, it is possible to produce frequency-doubling microwave signal with high frequency using low frequency modulator. Therefore, the requirement for high frequency modulA frequency-doubling optoelectronic oscillator using the nonlinear effect of the electro-optical modulator is proposed. By introducing a frequency divider, it is possible to produce frequency-doubling microwave signal with high frequency using low frequency modulator. Therefore, the requirement for high frequency modulator is weakened. Theoretical and experimental results show that, when the input microwave power is low, the modulator can introduce large additional noise, which severely deteriorates the phase noise of the optoelectronic oscillator. By introducing another microwave amplifier in the feedback path to reduce the additional noise, the phase noise of the frequency-doubling signal can be largely improved. When the fiber length is 1 km, the phase noise of the frequency-doubling signal is -104 dBc/Hz at 10 kHz frequency offset from 9 GHz, which is 6 dB worse than the conventional optoelectronic oscillator. Meanwhile, the output power is remained. The agreement of experimental results and theoretical analysis justifies the feasibility of this method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 806002 (2014)
Ultra-Short Optical Prescaled Clock Recovery Based on an Improved Optoelectronic Oscillator
Xie Xi, Huo Li, Wang Qiang, Wang Dong, and Lou Caiyun
An optoelectronic oscillator (OEO) on the basis of two phase modulators is proposed. The incident continuous wave (CW) light is modulated firstly by a phase modulator (PM). The PM is driven by the electrical prescaled clock extracted from this improved OEO. The spectrum of the modulated CW light is then sliced by an opAn optoelectronic oscillator (OEO) on the basis of two phase modulators is proposed. The incident continuous wave (CW) light is modulated firstly by a phase modulator (PM). The PM is driven by the electrical prescaled clock extracted from this improved OEO. The spectrum of the modulated CW light is then sliced by an optical band-pass filter (OBPF) on the blue side or red side to the original center wavelength. The generated 7.6 ps optical pulses are subsequently launched into a pulse compressor, which consists of a PM and a single-mode-fiber (SMF). Thereby, optical prescaled clock with a narrow width is then obtained. 25 GHz optical clock and electrical clock are experimentally extracted from 4×25 Gbit/s signal. The width of optical clock pulse is 3.1 ps, which corresponds to a duty cycle of 7.75%. The resulted timing-jitter (100 Hz to 10 MHz) is 135 fs. The carrier-to-noise ratio of electrical clock is 61.7 dB and its timing jitter (100 Hz to 10 MHz) is 118 fs..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 806003 (2014)
Polarization-Maintaining Photonic Crystal Fiber Hydrogen Sensor Based on Sagnac Interferometer
Yang Yuanhong, Wang Huan, Yang Fuling, Liu Qirong, Diao Xungang, Zhang Yi, Zhuang Zhi, and Mao Yongjian
A polarization-maintaining photonic crystal fiber (PM-PCF) hydrogen sensor based on Sagnac interferometer is proposed. A sensing model is established and experimentally studied and tested. With the facing target sputtering process, Pd/Ag composite film is deposited on PM-PCF fast and uniformly. The birefringence of PM-A polarization-maintaining photonic crystal fiber (PM-PCF) hydrogen sensor based on Sagnac interferometer is proposed. A sensing model is established and experimentally studied and tested. With the facing target sputtering process, Pd/Ag composite film is deposited on PM-PCF fast and uniformly. The birefringence of PM-PCF can be modified by the deformation of film after absorbing hydrogen, realizing the measurement of hydrogen concentration by detecting the wavelength shift of one specific valley. The results show that good repeatability is obtained within the measuring range of 4%. This sensor′s sensitivity is higher at low hydrogen concentration and the wavelength shift is 1.307 nm when the hydrogen concentration increases from 0% to 1%. The birefringence of the PM-PCF is not sensitive to temperature, restraining the interference brought up by the fluctuation of environment temperature..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 806004 (2014)
Optimal Design of Multi-Channel Fiber Bragg Grating Filters Based on Particle Swarm Optimization Algorithm
Liu Tundong, Ye Zengruan, Chen Jing, Tao Jiping, and Jiang Hao
With the increasing number of channels, fabricating a multi-channel fiber Bragg grating (FBG) filter requires a considerably high maximum index modulation, which is beyond a physically realizable level. Hence, an effective optimization method based on particle swarm optimization (PSO) algorithm and direct design methodWith the increasing number of channels, fabricating a multi-channel fiber Bragg grating (FBG) filter requires a considerably high maximum index modulation, which is beyond a physically realizable level. Hence, an effective optimization method based on particle swarm optimization (PSO) algorithm and direct design method to design a multi-channel FBG filter is proposed. By introducing the tailored group delay coefficients into the target reflectivity spectrum, a mathematical model aiming at minimizing the maximum index modulation of the grating is established. The PSO algorithm is employed to find the optimal group delay parameter for each channel. It leads to a more even distribution of the refractive index modulation, thereby reduces the maximum index modulation to a physically realizable level. Design examples of the 40-channel and 106-channel FBG filters both with uniform reflection spectra demonstrate that the proposed method yields a remarkable reduction in the maximum index modulation which is below 0.001..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 806005 (2014)
Quasi-Distributed Fiber Bragg Grating Sensing Network Based on Fiber Chaotic Laser
Wang Feifei, Zhang Li, Yang Lingzhen, and Liu Yanyang
A novel type of quasi-distributed fiber Bragg grating sensing system based on fiber chaotic laser is demonstrated. The light source is the wavelength tunable chaotic fiber laser. The identical weak fiber Bragg gratings are utilized as the sensors. According to delta function characteristics of the correlation of chaotiA novel type of quasi-distributed fiber Bragg grating sensing system based on fiber chaotic laser is demonstrated. The light source is the wavelength tunable chaotic fiber laser. The identical weak fiber Bragg gratings are utilized as the sensors. According to delta function characteristics of the correlation of chaotic light sources, the correlation peaks of the cross-correlation between the reflected light from sensors and reference light from chaotic fiber laser can locate the positions of the sensors. The center wavelength of the identical weak fiber Bragg grating with stress can be demodulated by using tunable optical fiber grating filter and the quasi-distributed fiber Bragg grating sensing system is realized. The experimental results show that the single fiber link of the identical fiber Bragg grating sensor using the tunable chaotic fiber laser is realized and it is expected to achieve the intensive weak fiber grating sensing network..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 806006 (2014)
Holography
A Focusing Criterion Function for Automatic Reconstruction of Digital Holograms
Tang Chunming, Liu Yucui, and Yu Xiang
The autofocus is a key technique for automatic reconstruction in digital holography, and the performance of the focusing criterion function influences the effect of the autofocus greatly. After analyzing and researching existing focusing criterion functions and studying the theories about image definition, for the digiThe autofocus is a key technique for automatic reconstruction in digital holography, and the performance of the focusing criterion function influences the effect of the autofocus greatly. After analyzing and researching existing focusing criterion functions and studying the theories about image definition, for the digital holograms of marine microorganism, a new focusing criterion function is proposed. The method proposed is based on features that local standard deviation distribution is able to reflect image detail information and standard deviation which is taken as measurement of discrete degree has high robustness. It makes the discrete degree of reconstruction image detail as image definition index, and makes reconstruction distance corresponding to maximum of the definition as the best distance to accomplish the autofocus. Simulation results illustrate that compared with the existing methods, the proposed method has the stronger single peak, higher sensibility and signal to noise ratio (SNR) and better unbiasedness. In addition, it has strong universal and practical for the digital holograms of marine microorganism. So it can satisfy the requirements of automatic reconstruction of the marine microorganism holograms..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 809001 (2014)
Sub-Pulse Train Generation with Continuously Adjustable Pulse Interval Based on Birefringent Crystal
Sun Xuna, Yang Xiaoping, Yang Yong, Ma Zhonghong, Ge Qi, and Xu Zhenxin
To achieve real-time detection with adjustable exposure interval in ultrafast events, a triple-wedge crystal pulse splitting method with continuously adjustable pulse interval is proposed for obtaining collinear propagated sub-pulses. The generated sub-pulses have the characteristics of equal energy and high similarityTo achieve real-time detection with adjustable exposure interval in ultrafast events, a triple-wedge crystal pulse splitting method with continuously adjustable pulse interval is proposed for obtaining collinear propagated sub-pulses. The generated sub-pulses have the characteristics of equal energy and high similarity. Moreover the compact structure of the triple-wedge crystal makes it easier to be embed into the optical system. The accurate relationship between the pulse interval and the structural angle，dimension and moving distance of the birefringent crystal is mathematically derived. A linear relationship exists between the pulse interval and the moving distance of the crystal at a given structural angle and crystal size. The impacts of error terms and dispersion on the pulse interval are theoretically analyzed. The feasibility of the proposed method is confirmed by mathematical analyzation and experimental results. The results will provide a reference knowledge base for multi-pulse splitting..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 809002 (2014)
Image Processing
Research of Lightfield Acquisition and Reconstruction Based on Mask
Liu Yongchun, Gong Huajun, and Shen Chunlin
In view of the existed problems of the existing light field acquisition methods: high hardware cost and big volume in camera array acquisition; to be limited to static light field in single camera ordinal sampling; low spatial resolution of the light field in integral imaging light field acquisition. A method of light In view of the existed problems of the existing light field acquisition methods: high hardware cost and big volume in camera array acquisition; to be limited to static light field in single camera ordinal sampling; low spatial resolution of the light field in integral imaging light field acquisition. A method of light field acquisition and reconstruction based on a mask has been studied. A light field acquisition model is set up. Light field imaging process is analyzed in Fourier domain. Utilizing a random mask to randomly encode the light field, which leads to get a coded sensor image. An overcomplete light-field dictionary is learned offline. The coded sensor image is optimized through compressed sensing and the overcomplete light-field dictionary. The original light field is restored..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 810001 (2014)
Image Deblurring with Adaptive Signal-Noise Ratio Estimation for Computational Imaging System
Lu Huimin, Xu Ming, and Li Xun
It is significant to realize effective image deblurring for improving the performance of the computational imaging system based on spherical optics. The image blurring model in the spherical optics is analyzed, and the image deblurring algorithm based on Wiener deconvolution is introduced. To deal with the problem thatIt is significant to realize effective image deblurring for improving the performance of the computational imaging system based on spherical optics. The image blurring model in the spherical optics is analyzed, and the image deblurring algorithm based on Wiener deconvolution is introduced. To deal with the problem that the signal-noise ratio (SNR) should be estimated accurately in the image deblurring based on Wiener deconvolution, a novel adaptive SNR estimation algorithm based on image denoising is proposed. The experiments are performed using the images acquired by Zemax software and the implemented prototype of the computational imaging system based on spherical optics. The results show that the noise variance and SNR can be estimated with high accuracy by using the proposed algorithm, and good image deblurring results can be achieved using Wiener deconvolution with the adaptively estimated SNR, so the clear and high resolution images can be acquired by the computational imaging system based on spherical optics after integrating the work presented..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 810002 (2014)
Image Encryption Based on Iterative Amplitude-Phase Retrieval and Nonlinear Double Random Phase Encoding
Chen Yixiang, and Wang Xiaogang
A novel image encryption method based on iterative amplitude-phase retrieval and nonlinear double random phase encoding is proposed. In this method, a fake image is first used to generate the cipher text with the help of two public keys in the nonlinear double random phase encoding scheme. Two private keys are generateA novel image encryption method based on iterative amplitude-phase retrieval and nonlinear double random phase encoding is proposed. In this method, a fake image is first used to generate the cipher text with the help of two public keys in the nonlinear double random phase encoding scheme. Two private keys are generated in the encryption process, where the original image to be encoded and the cipher text are applied as two constraints in the fast iterative amplitude-phase retrieval algorithm. The decryption processes can be finished in linear doubled random-phase encoding system based on 4f system. This encryption method has the advantages of fast convergence speed and high security. The proposed image encryption method has a resistance against on the amplitude-phase retrieval-based attack. The theoretical analysis and simulation experiments both validate the feasibility and security of the proposed scheme..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 810003 (2014)
A FBG Spectrum Peak Detection Technique Based on Steger Image Algorithm
Wang Qiaoni, and Yang Yuanhong
A super Gaussian model is established to describe the characteristics of real fiber Bragg grating (FBG) reflective spectrum. Utilizing image processing technique, a FBG peak detection technique based on Steger image algorithm is proposed, which provides a modified formula for the condition of asymmetric spectrum and a A super Gaussian model is established to describe the characteristics of real fiber Bragg grating (FBG) reflective spectrum. Utilizing image processing technique, a FBG peak detection technique based on Steger image algorithm is proposed, which provides a modified formula for the condition of asymmetric spectrum and a sub-step modified formula. Steger peak detection algorithm performs the function of both filter and peak detector to help eliminate the influence of noise, step and asymmetrical spectrum. Theoretical simulations and practical experiments are carried out to estimate the performance of this algorithm under different steps, signal noise ratio (SNR) and level of asymmetry. The results show that the proposed algorithm shows better adaptability and higher accuracy than the Centroid method and Gaussian curve fitting..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 810004 (2014)
Imaging Systems
Active Compensation of Thermal Aberrations in Lithographic Projection Lens
Chen Hua, Su Dongqi, Sui Yongxin, Zhang Mingchao, Tian Wei, Yang Huaijiang, and Zhang Wei
Thermal aberrations caused by absorption of laser energy are the key factors that make the image performance of lithographic projection lens degrade. Compensation of thermal aberrations is inevitable. A new compensation method of wavefront aberrations by controllable heating of a lens using film heater matrix is presenThermal aberrations caused by absorption of laser energy are the key factors that make the image performance of lithographic projection lens degrade. Compensation of thermal aberrations is inevitable. A new compensation method of wavefront aberrations by controllable heating of a lens using film heater matrix is presented. For the refractive index of glass changes with temperature, heating on the periphery of a lens will produce a controlled wavefront change that can compensate for the system′s thermal aberrations. The feasibility of the compensation method is validated by compensating the wavefront of a plate lens. The results show that the wavefront of lens changes from 12.52 nm root mean square (RMS) to 2.95 nm (RMS) after compensation, indicating that the compensation method is effective and feasible..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 811001 (2014)
Foundation and Application of Model for Multilayers Analysis in Extreme Ultra-Violet Lithography Projection
Wang Jun, Jin Chunshui, Wang Liping, Guo Benyin, and Yu Bo
The thickness of multilayer coatings in extreme ultraviolet lithography (EUVL) projection system is about 300 nm which is much greater than the work wavelength of 13.5 nm. The most energy can not punch the substrate and optical path difference of dozens of wavelength is induced. Then the image degrades. A model named eThe thickness of multilayer coatings in extreme ultraviolet lithography (EUVL) projection system is about 300 nm which is much greater than the work wavelength of 13.5 nm. The most energy can not punch the substrate and optical path difference of dozens of wavelength is induced. Then the image degrades. A model named equivalent work surface (EWS) is built up for coating analysis based on the principle of energy conservation. From the point of erengy modulation, the EWS model transforms the complex physical optics into brief and intuitive geometrical optics, getting recognizable data for commercial softwares. Finally with the aid of EWS, a diffraction-limited virtually-coated system is confirmed, proving the significance of the EWS model. The model can be used for the direction of following alignment and multi-reflection system optimization and coating analysis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 811002 (2014)
Instrumentation, Measurement and Metrology
Three-Dimensional Coordinate Measurement with Point-Diffraction Interferometer Based on Levenbery-Marquardt Algorithm
Wang Daodang, Wang Fumin, Chen Xixi, Kong Ming, and Zhao Jun
Aiming at the precise demodulation of three-dimensional coordinate with point-diffraction interferometer, a method based on Levenbery-Marquardt (L-M) algorithm is proposed for three-dimensional coordinate measurement. With the phase distribution demodulated in point-diffraction interferometry, a double-iterative methodAiming at the precise demodulation of three-dimensional coordinate with point-diffraction interferometer, a method based on Levenbery-Marquardt (L-M) algorithm is proposed for three-dimensional coordinate measurement. With the phase distribution demodulated in point-diffraction interferometry, a double-iterative method based on L-M algorithm is applied to reconstruct the three-dimensional coordinate of point-diffraction source. Both computer simulation and experimental measurement comparing with coordinate measurement machine are carried out to verify the feasibility of the proposed measurement method. Experimental results show that the proposed method can both reach the measurement precision in the order of micron within a 100 mm×100 mm×300 mm working volume. This measurement method does not rely on the initial iteration value, and also has high measurement precision, fast processing speed and preferable anti-noise ability. It is of great practicality for measurement of three-dimensional coordinate and calibration of measurement system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 812001 (2014)
Indoor Test Method of Attitude Measurement Accuracy of Photoelectric Theodolite
Tian Liude, Liu Chaohui, Zhao Jianke, Duan Yanxuan, Pan Liang, Zhao Huaixue, Duan Jiong, Long Jiangbo, and Wang Zhengfeng
In order to realize indoor test and evaluation of attitude measurement accuracy of range optical attitude measurement equipment, some research work has been done. The principle of intersection surveying the attitude of spatial axisymmetric target with photoelectric theodolites is introduced. The device is introduced toIn order to realize indoor test and evaluation of attitude measurement accuracy of range optical attitude measurement equipment, some research work has been done. The principle of intersection surveying the attitude of spatial axisymmetric target with photoelectric theodolites is introduced. The device is introduced to simulate the attitude of infinite object indoor, which is composed of measurement rack, collimator, light source, and targets with different angles. Precise mathematical model is established, which is relation with target attitude angle and azimuth and elevation of target feature points. Firstly, several feature points on the target are measured with high precision theodolite. Secondly, according to the above mathematical model, the target attitude is fitted by using the least square method, then, the target attitude angle is got. It has been proved that the calibration precision can reach 0.05°. Consider the calibration results as true value of the target attitude angle, dynamic measurements are performed on the same target by using photoelectric theodolite and attitude measurement error of the theodolite can be obtained in comparsion with two measurement results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 812002 (2014)
Non-Null Annular Subaperture Stitching Interferometry for Aspheric Test
Zhang Lei, Tian Chao, Liu Dong, Shi Tu, Yang Yongying, and Shen Yibing
A novel non-null annular subaperture stitching interferometry (NASSI) is proposed for steep aspheric test. It combines the non-null test and annular subaperture stitching method, in which a partial null lens is employed as an alternative to the transmission sphere, to generate aspherical wavefront as the reference. TheA novel non-null annular subaperture stitching interferometry (NASSI) is proposed for steep aspheric test. It combines the non-null test and annular subaperture stitching method, in which a partial null lens is employed as an alternative to the transmission sphere, to generate aspherical wavefront as the reference. The aspherical wavefront has a better performance in matching the local slope of subapertures. This approach greatly reduces the subaperture number required to cover the full-aperture of test surface. On one hand, subapertures are broadened and thus the stitching accuracy increased. For another, accumulated error is decreased. Based on the system modeling, the retrace error can be corrected for each subaperture individually and the testing accuracy is further improved. A numerical simulation exhibits the high theoretical accuracy of the NASSI method, in which a high-order aspheric of 25 μm asphericity is tested. Comparing experiments with Zygo VerifireTMAsphere interferometer for paraboloid, whose diameter is 101 mm, are performed. The peak-valley error is better than λ/20, the root-mean-square error is better than λ/100. The high accuracy and good repeatability of NASSI are presented..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 812003 (2014)
Analysis of Diffraction Wavefront Error Caused by Alignment Error of Pinhole
Gao Fen, Jiang Zhuangde, and Lin Bing
Alignment error of the pinhole is the main error factor that affects the quality of diffraction reference wavefront in a point diffraction interferometer. Based on Rayleigh-Sommerfeld vector diffraction theory, a theoretical model of non-paraxial Gaussian beams diffracted through a pinhole is established, and diffractiAlignment error of the pinhole is the main error factor that affects the quality of diffraction reference wavefront in a point diffraction interferometer. Based on Rayleigh-Sommerfeld vector diffraction theory, a theoretical model of non-paraxial Gaussian beams diffracted through a pinhole is established, and diffraction wavefront error caused by different alignment errors is numerically analyzed. The influence of focusing spot size is especially considered. The research results show that the introduction of even a small alignment error can make the diffraction wavefront error increases quickly, diffraction wavefront error increases linearly as the alignment error increases; under same alignment error, the bigger the focusing spot size, the smaller the diffraction wavefront error. In order to reach the same level of diffraction wavefront accuracy, the allowable alignment error increases nearly in same multiples as the focusing spot size increases. Diffraction wavefront error distribution of 0.5~3 μm pinholes in different spot size and alignment error are acquired in the analysis, it can provide favorable reference data for the selection of focusing lens, determination of pinhole alignment accuracy requirements and the evaluation of diffraction wavefront error in certain condition..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 812004 (2014)
Lasers and Laser Optics
Study on a Light-Intensity Control System of Total Reflection Prism Laser Gyros
Jia Huixia, Zhang Yingmin, Zhang Qiong, Li Ganghu, and Ma Jiajun
The light intensity control system and the cavity length control system are used in the design of the laser gyro. Transfer functions of the light intensity control system of prism laser gyros are established based on the theory of the control system. The equivalent mathematical model of the ring laser in the light inteThe light intensity control system and the cavity length control system are used in the design of the laser gyro. Transfer functions of the light intensity control system of prism laser gyros are established based on the theory of the control system. The equivalent mathematical model of the ring laser in the light intensity control system is established by experiments and tests. Based on theoretical analysis and Matlab simulation, performance of the laser gyro light intensity control system can be evaluated accurately. It offers theoretic base for system design and improves performance of the laser gyro and debugging efficiency..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 814001 (2014)
High-Order Harmonic Mode-Locked Yb-Doped Fiber Laser with All Normal Dispersion
Zhu Xiaojun, Zhang Guoan, Cao Zhanghua, Zeng Feng, and Zhu Youhua
A high-order harmonic and passively mode-locked Yb-doped with all-normal dispersion fiber laser is reported and demonstrated. With the mode-locking mechanism of nonlinear polarization evolution (NPE) effect and a cascade long period fiber grating (C-LPFG) as an all-fiber format spectral filter for the strong pulse shapA high-order harmonic and passively mode-locked Yb-doped with all-normal dispersion fiber laser is reported and demonstrated. With the mode-locking mechanism of nonlinear polarization evolution (NPE) effect and a cascade long period fiber grating (C-LPFG) as an all-fiber format spectral filter for the strong pulse shaping, a maximum of 21th-order harmonic mode-locked (HML) Yb-doped fiber laser can be tunably achieved with the repetition rate from 1.544 MHz to 32.42 MHz. It is further confirmed that the order of the HML is dependent on the cavity length and the pump power..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 814002 (2014)
Single-Pass High-Gain 1.9 μm Optical Fiber Gas Raman Laser
Wang Zefeng, Yu Fei, William J Wadsworth, and Jonathan C Knight
A single-pass high-gain 1.9 μm fiber gas laser, based on vibrational stimulated Raman scattering in a hydrogen-filled hollow core photonic crystal fiber, is reported. Efficient conversion to the first-order vibrational Stokes wave of 1907 nm is obtained in a low loss negative curvature hollow core fiber with a length oA single-pass high-gain 1.9 μm fiber gas laser, based on vibrational stimulated Raman scattering in a hydrogen-filled hollow core photonic crystal fiber, is reported. Efficient conversion to the first-order vibrational Stokes wave of 1907 nm is obtained in a low loss negative curvature hollow core fiber with a length of 6.5 m, which is filled with high pressure hydrogen pumped with a linearly polarized 1064 nm microchip pulse laser. The maximum power conversion efficiency, which is more than 27% at 2.3 MPa hydrogen pressure, and a quantum conversion efficiency of 48% are achieved. The maximum laser average power is about 10 mW，and the maximum peak power is more than 2000 W. It provides a potentially effective method to obtain broadly tunable mid-IR fiber lasers of high power and narrow linewidth..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 814004 (2014)
Machine Vision
Correspondence Method Based on Spatial Intersection in Portable Visual Metrology
Long Changyu, Zhu Jigui, Guo Yin, and Lin Jiarui
In portable visual metrology, a large number of un-coding targets are stuck on the surface of the measured object. Since the shapes of the image points are similar in different station images, there is not sufficient information to classify and identify the image points. Therefore, matching of un-coding targets betweenIn portable visual metrology, a large number of un-coding targets are stuck on the surface of the measured object. Since the shapes of the image points are similar in different station images, there is not sufficient information to classify and identify the image points. Therefore, matching of un-coding targets between multiple images is an important task in portable visual metrology. Numerous researches prove that epipolar line matching method is an effective way to do the match. However, the camera is not calibrated before the measurement in portable visual metrology. The solving accuracy of fundamental matrix is low due to image distortion, which results in great amount of mismatches. To solve this problem, an un-coding points matching method based on spatial intersection is proposed. With the automated match of coding targets between multiple images, internal and external parameters of stations are obtained combining with bundle adjustment optimization. Utilizing these parameters, two-dimensional image points are re-projected into corresponding three-dimensional spatial lines and the matching image points can be determined with the intersecting relationship of lines on space. Multiple experiments indicate that this method can find more match points than epipolar line matching method and is more suitable for portable visual metrology..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 815001 (2014)
Nonlinear Optics
Harmonic Conversion Rule for Gaussian Pulse with Nonideal Conditions
Li Keyu, Feng Bin, Wang Fang, Jia Huaiting, Han Wei, Zhao Runchang, and Xiang Yong
The harmonic conversion rule of I/II angle-tuned third harmonic gemeration (THG) system will be far away from the ideal rule on actual large-aperture and high-intensity laser facility. To study actual harmonic conversion rule and guide the crystal debugging, the nonideal conditions, such as 1ns Gauss pulse, different wThe harmonic conversion rule of I/II angle-tuned third harmonic gemeration (THG) system will be far away from the ideal rule on actual large-aperture and high-intensity laser facility. To study actual harmonic conversion rule and guide the crystal debugging, the nonideal conditions, such as 1ns Gauss pulse, different wave radius and crystal loss have been studied. It is proved that the THG external efficiency will reduce 10% than flat-temporal pulse. To obtain the highest THG efficiency, the optimal SHG internal tuned angle is not 220 μrad but 160 μrad impacted by 1 ns Gauss pulse and crystal loss. And the optimal second harmonic generation (SHG) internal efficiency is not 67% but 60%~63%. The higher of crystal loss, the lower of SHG internal efficiency. And the higher of 1ω intensity, the greater of infection of wave radius and divergence angle on harmonic conversion..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 819001 (2014)
Propagation of Hyperbolic-Cosine Gaussian Beams in Strongly Nonlocal Media
Dai Zhiping, Yang Zhenjun, Zhang Shumin, Pang Zhaoguang, and You Kaiming
With the nonlinear Schrodinger equation descripting of beam propagation in strongly nonlocal media, the interaction and propagation properties of (2+1)-dimensional hyperbolic-cosine Gaussian beams in strongly nonlocal nonlinear media are studied. The analytical expressions of propagation of hyperbolic-cosine Gaussian bWith the nonlinear Schrodinger equation descripting of beam propagation in strongly nonlocal media, the interaction and propagation properties of (2+1)-dimensional hyperbolic-cosine Gaussian beams in strongly nonlocal nonlinear media are studied. The analytical expressions of propagation of hyperbolic-cosine Gaussian beams in strongly nonlocal nonlinear media and second moment beam width are obtained, while the interactions between two hyperbolic-cosine Gaussican beams are resolved and analysized numerically. The results show that when the incidence is a single beam, there exists a critical power. When the input power is equal to the critical power, the second moment beam width remains invariant on propagation, otherwise the second moment beam width varies with a period during propagation. When two hyperbolic-cosine Gaussian beams propagate together, they always attract each other, and the transverse intensity distribution becomes complicated. The on-axis intensity evolution and the intensity distributions of the interaction between two beams during propagation are discussed in detail..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 819002 (2014)
Optical Design and Fabrication
Selecting System Compensators for Small Scale Projected Objective Using Displaced Parameters Vector
Zhao Yang, Wang Ping, Zhao Lei, Liu Chunlai, Hua Yangyang, and Men Shudong
Because of the large number of the lenses in a small scale projected objective, it is unsuitable to use a traditional method that each compensator only compensates the corresponding misalignment. A sensitivity matrix is utilized to solve this problem. The sensitivity matrix is decomposed using singularly valuable decomBecause of the large number of the lenses in a small scale projected objective, it is unsuitable to use a traditional method that each compensator only compensates the corresponding misalignment. A sensitivity matrix is utilized to solve this problem. The sensitivity matrix is decomposed using singularly valuable decomposition method. The values and signs of displaced parameters vector are analyzed, and the correlations among each displaced parameter are obtained. A method of selecting a set of optimum combination of system compensators which only need to analyze a few displaced parameters vectors is proposed. The selected compensators are proved as correct by massive simulation calculations with the aiding of macro commands modes. After the original assembling, a pre-aligning procedure of optical system is carried out to ensure the feasibility of the aligning scheme. Test results show that the wave front errors root mean square (RMS) reduced to 29.6 nm from 70 nm after compensating, which is better than the requirements of the qualifications. The results prove the methods of selecting compensators are right and effective..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 822001 (2014)
Research on the Optical Design and Stray Light Suppression for Off-Axis Reflective Space Astronomical Telescope
Zhu Yang, Zhang Xin, Wu Yanxiong, Qu Hemeng, Zhang Jizhen, and Wang Lingjie
In order to aim at a telescope system with large F number, long focal length, miniaturized dimension, high image quality and high stray light suppression, a three mirror off-axis anastigmatic telescope is designed based on the Cook type, of which f′ is 24 m, F number is 16, field of view is 1.6°×1°. The In order to aim at a telescope system with large F number, long focal length, miniaturized dimension, high image quality and high stray light suppression, a three mirror off-axis anastigmatic telescope is designed based on the Cook type, of which f′ is 24 m, F number is 16, field of view is 1.6°×1°. The outer baffle and the structures inside are designed. The stray light of telescope system is analyzed with stray light program to calculate the point sources transmittance (PST). The forward and backward ray tracing is combined to find the key surface and modify the optical and mechanical structure with optimization and iteration. The result shows that the modulation transfer functions (MTF) approaches the diffraction limit at all fields. When the evadable angle out of the field is 40°, the PST is less than 10-11 and the system can achieve the requirement of stray light suppression..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 822002 (2014)
Freeform Surfaces Reconstruction Based on Zernike Polynomials and Radial Basis Function
Ye Jingfei, Gao Zhishan, Liu Xiaoli, Wang Wei, and Zhang Congyang
For optical freeform surfaces with steep slopes, the accuracy of overall surface shape reconstruction by modal method is limited and cannot meet the requirements, and the local surface features cannot be characterized accurately. A method based on Zernike polynomials and radial basis function to reconstruct freeform suFor optical freeform surfaces with steep slopes, the accuracy of overall surface shape reconstruction by modal method is limited and cannot meet the requirements, and the local surface features cannot be characterized accurately. A method based on Zernike polynomials and radial basis function to reconstruct freeform surface is proposed to improve the freeform surface reconstruction accuracy. The entire freeform surface is decomposed into many circular subdomains. The local surface patch is fitted by Zernike polynomials acting as base functions in each subdomain and the overall surface is formed by radial basis function. Numerical experiments are carried out with reconstruction accuracy analysis for five different surfaces. According to the experiments, freeform surface reconstruction accuracy is better than nanometer level. The adaptability and high accuracy of the proposed method are verified, which has great application prospect in the manufacturing and measuring of modern optical systems. At the same time, a few key issues have been discussed and analyzed in the freeform surface reconstruction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 822003 (2014)
Two-Lens Athermalized Infrared Telephoto Objective
Zhang Xin, Qiao Yanfeng, Zhu Mingchao, He Fengyun, and Jia Hongguang
A method to design athermalized infrared two-lens telephoto objectives is proposed to reduce the number of lenses and simply the structure of an athermal optical system. The telephoto structure is composed of a front refractive-diffractive positive single lens and a rear negative single lens. A diffractive surface is uA method to design athermalized infrared two-lens telephoto objectives is proposed to reduce the number of lenses and simply the structure of an athermal optical system. The telephoto structure is composed of a front refractive-diffractive positive single lens and a rear negative single lens. A diffractive surface is used to compensate most of chromatic aberration and a small amount of thermal aberration, and residual aberrations are balanced by the rear negative lens. A long-wavelength infrared objective used for uncooled focal plane arrays is designed, whose focal length is 120 mm, F number is 1.2 and telephoto ratio is 0.9. The designed modulation transfer function (MTF) is close to the diffraction limit and the measured result of MTF is greater than 0.45 at the spatial frequency of 30 lp/mm. The results of temperature tests show that the target image remained sharp in the temperature range from -40 ℃ to 60 ℃. The proposed two-lens structure can be applied in airborne and missile-borne electro-optical equipments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 822004 (2014)
Optical System Design of Multi-Model Hyperspectral Imager for Spaced-Based Atmospheric Remote Sensing
Xue Qingsheng
Space-based atmospheric remote sensing urgently requires multi-model hyperspectral imager. Based on the research objective of multi-model space-based atmospheric remote sensing, an optical system of space-based multi-model hyperspectral imager with nadir and limb models is designed using a scanning system, an off-axis Space-based atmospheric remote sensing urgently requires multi-model hyperspectral imager. Based on the research objective of multi-model space-based atmospheric remote sensing, an optical system of space-based multi-model hyperspectral imager with nadir and limb models is designed using a scanning system, an off-axis parabolic telescope and a spectral imaging system with a cascade double spectrometer. The instantaneous field of view of hyspectral imager is 1.8°×0.045°, relative-aperture is 1/2, and working waveband is from 250 nm to 500 nm. The waveband from 250 nm to 500 nm is devided two wavebands, one is from 250 nm to 330 nm, the other one is from 320 nm to 500 nm. Ray tracing, optimization are performed by ZEMAX-EE software. The root mean square (RMS) spot radius for different wavelengths are less than 9.5 μm. The spectral resolution is 0.17 nm in the waveband from 250 nm to 330 nm, the spectral resolution is 0.37 nm with waveband from 320 nm to 500 nm, and both of them satisfy the requirement of specification which is less than or equal to 0.6 nm. The modulation transfer function (MTF) for different wavelengths of hyperspectral imager is more than 0.9 at characteristic frequency in the spatial direction. The design results satisfy the requirements of imaging quality, and is suitable for the application of space-based remote sensing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 822005 (2014)
Optical Devices
Testing and Monochromatic Light Verification of Optical Path Difference Distribution of Liquid Crystal Devices Under the White Light
Qi Mingchun, Huang Ziqiang, and Wang Xiangru
A approach that liquid crystal variable retrader (LCVR) is used as a compensator to test the 2-D distribution of optical path diffevence (OPD) of liquid crystal device under the condition of white light irradiation of polarizing microscope is proposed. The system used for testing and verifying 2-D distribution of OPD uA approach that liquid crystal variable retrader (LCVR) is used as a compensator to test the 2-D distribution of optical path diffevence (OPD) of liquid crystal device under the condition of white light irradiation of polarizing microscope is proposed. The system used for testing and verifying 2-D distribution of OPD under the orthogonal polarization is set up. The OPD of LCVR is tested by using the system. The results tested by using this system and the Senamont are calibrated, the error is within 3%. On that basis, the 2-D distribution of OPD of liquid crystal light deflecter (DLD) and optical addressable-transimission space light modulater (OA-TSLM) are measured by using that system, and their regularities of distribution can also be obtained. It can be used to test the liquid crystal-optical phased array (LC-OPA), when the method is further optimized. Research significance lies in many aspects, such as, the 2-D distribution of OPD′ microstructure, which the electronic liquid crystal devicesare in multiple wavelengths and include near-infrared band can be used to test by this way with the system. The flyback,phase valley and nonlinear driving voltage, LC-OPA′ characteristics can be corrected and detected. It can also be used for optical addressable-space light modulator (OA-SLM) of gamma correction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 823001 (2014)
Formation and Suppression of Multi-Component Exciplex in White Organic Light Emitting Devices
Zhao Jiang, He Zhiqun, Zhang Jiao, Zhang Xiaojin, Yang Liu, Meng Tengfei, Liu Shujie, Liang Chunjun, and Liu Shu
A systematical investigation in fabrication of white organic light emitting devices (OLED) in combination of fluorescent and phosphorescent materials is reported. In these devices, OXD-7 as blue layer and Ir(MDQ)2acac as a red dopant are doped into host material(s) to make dual-band white OLED. It is discovered that a A systematical investigation in fabrication of white organic light emitting devices (OLED) in combination of fluorescent and phosphorescent materials is reported. In these devices, OXD-7 as blue layer and Ir(MDQ)2acac as a red dopant are doped into host material(s) to make dual-band white OLED. It is discovered that a joint interaction between three components, OXD-7, Alq3 and NPB cause a formation of electroplex in multilayered structure. And a red shift can be observed, which undermines the device performance. This problem can be solved by inserting TDAF as an intermediate layer, which effectively inhibit the electroplex formation and hence eliminate the red shift. Thus, the luminous intensity and efficiency of device are improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 823002 (2014)
Influence of Pixel-Mapping Ratio on Hardware-in-the-Loop Simulation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In the design process of hardware-in-the-loop scene simulator of a guidance system, in order to establish an accurate basis for the selecting of the pixel-mapping-ratio (PMR), the influence of PMR on the simulation has been analyzed based on the sampling properties of the detector of unit under test and the spatial ligIn the design process of hardware-in-the-loop scene simulator of a guidance system, in order to establish an accurate basis for the selecting of the pixel-mapping-ratio (PMR), the influence of PMR on the simulation has been analyzed based on the sampling properties of the detector of unit under test and the spatial light modulator of simulator. The unique characteristic of the spectral distribution of the random targets has been introduced into the simulation model to calculate the modulation transfer function. Furthermore, the modulation transfer function curves at different PMR and phases have been obtained. The results show that if the PMR is either 0.31 or 0.71, the influence of the phase variation on the modulation transfer function is negligible, and the modulation transfer function′s value shows minimum attenuation and good stability. The quantitative criterion can be provided in the design of scene simulators..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 823003 (2014)
Design and Experiment of Focal Plane for High Speed TDI CCD Space Camera
Jia Xuezhi, Zhang Lei, An Yuan, and Jin Guang
Time delay integration (TDI) CCD focal plane assembly is one of the most important components for a space camera, which mainly fulfill photoelectric conversion and output video signal of analog CCD. Due to the hard condition resulted from the transportation and launch of a space camera, it is difficult to keep a TDI CCTime delay integration (TDI) CCD focal plane assembly is one of the most important components for a space camera, which mainly fulfill photoelectric conversion and output video signal of analog CCD. Due to the hard condition resulted from the transportation and launch of a space camera, it is difficult to keep a TDI CCD with high interleaving precision. Therefore, in this work, we design a TDI CCD focal plane assembly with a good performance based on the optimization both on structural control and thermal control. According to the analysis of the factors that affect the interleaving precision of a TDI CCD focal plane assembly and the maximal error of three axes theoretically, we design an especial structure for a TDI CCD focal plane assembly to keep the high interleaving precision of a TDI CCD which can fit the hard condition for the transportation and launch of a camera and the harsh on-orbit operating temperature. The effectiveness of the modified TDI CCD focal plane assembly is supported by the results obtained from dynamic test and thermal vacuum test. For the dynamic test, the response result shows that the assembly can conquer the interference of dynamic environment and keep a high interleaving precision of TDI CCD. For the thermal vacuum test, thermal balance test indicates that the highest temperature of TDI CCD is 30 ℃ in 1.5 min, which can work properly. The interleaving precision of focal plane is done after the dynamic environment and thermal vacuum tests. The linearity error of the TDI CCD is 3.5 μm, the interleaving error is 4 μm, the parallelism error between two lines of the TDI CCD is 3.5 μm, and the coplanar error of 4 TDI CCD is 5 μm. These results satisfy the optical design very well. Therefore, the aforementioned course proves that this design is feasible and precise, and it can achieve a high interleaving precision for a TDI CCD..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 823004 (2014)
Quantum Optics
Quantum Properties of a New Three-Mode Squeezed Vacuum State
Lu Daoming
The three-mode squeezed vacuum state is proposed by using of a new three-mode squeezing operator acting on a three-mode vacuum state. With two of the three modes measured, the influence of the selective measurement on squeezing effect, antibunching effect and photon statistical distribution of the third mode is discussThe three-mode squeezed vacuum state is proposed by using of a new three-mode squeezing operator acting on a three-mode vacuum state. With two of the three modes measured, the influence of the selective measurement on squeezing effect, antibunching effect and photon statistical distribution of the third mode is discussed. The results obtained show that on the one hand, if the first and the second modes are selectively measured in a two-mode squeezed state, the state vector of the third mode collapses onto single-mode squeezing state and squeezing of the third mode is strengthened. On the other hand, nonclassical properties of photon statistical distribution is strongthened by measuring the quantum state, which has no effect on antibunching of the third mode..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 827001 (2014)
Algorithm of Multidimensional Reconciliation for Continuous-Variable Quantum Key Distribution
Wang Yunyan, Guo Dabo, Zhang Yanhuang, Wang Xiaokai, and He Zhuanling
Data reconciliation is an important part of quantum key distribution, which is also the key step for the continuous-variable quantum key distribution (CVQKD). Based on Leverrier′s prove about the security of CVQKD, a low density parity check code (LDPC) algorithm for multidimensional reconciliation is presented. The miData reconciliation is an important part of quantum key distribution, which is also the key step for the continuous-variable quantum key distribution (CVQKD). Based on Leverrier′s prove about the security of CVQKD, a low density parity check code (LDPC) algorithm for multidimensional reconciliation is presented. The minimum convergence signal-to-noise ratio threshold of the algorithm is evaluated and the corresponding maximum key transmission distance of the CVQKD scheme is also estimated. By calculating the reconciliation efficiency and analyzing the noise, the maximum safe key capacity is further calculated. Simulation results indicate that the transmission distance between Alice and Bob increases from 30 km to 47 km, the decoding speed is 4 times of the sliced error correction (SEC) protocol, and the raw secret rate can reach 8.61 kb/s..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 827002 (2014)
Remote Sensing and Sensors
A Method to Select Receiving Channels for the Multi-Spectral Earth Observation LiDAR
Du Lin, Ma Yingying, Zhu Bo, Shi Shuo, Gong Wei, and Song Shalei
A multi-spectral earth observation LiDAR is a new means to monitor vegetation, and its applications are increasingly widespread. The existing multi-spectral earth observation LiDAR system adopts blazed grating and multi-channel photosensitive detector arrays as its data reception mode. Increasing the number of receivinA multi-spectral earth observation LiDAR is a new means to monitor vegetation, and its applications are increasingly widespread. The existing multi-spectral earth observation LiDAR system adopts blazed grating and multi-channel photosensitive detector arrays as its data reception mode. Increasing the number of receiving channels only to improve the spectral resolution and receiving range will cause such problems as data redundancy, difficulty in system integration and high cost etc. How to determine the number of channels and how to adjust the characteristic wavelength just to the center of the appropriate channel by selecting blazed grating and its blazed wavelength is discussed; in the meantime the characteristic wavelength outside the channel or not at the center of the channel is amended by using the feature weighting method based on the principal component analysis. Thus, not only the effectiveness on receiving information is improved, but also the wavelength selection theory is supplemented to some extent while spectral information of vegetation is not reduced, and the adaptation of the multi-spectral earth observation LiDAR system in practical applications is improved as well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 828001 (2014)
Electrically Controlled Parabolic Wavefront Scanner in Down-Looking Synthetic Aperture Imaging Ladar
Lu Zhiyong, Sun Jianfeng, Zhi Ya′nan, Zhou Yu, Liu Fuchuan, and Liu Liren
Electrically controlled parabolic wavefront scanner in down-looking synthetic aperture imaging ladar (SAIL) is developed. The scanner is composed of electro-optic crystal and cylindrical lens with the advantages of small shape and high-speed. A linear phase modulation in electro-optic crystal is generated by four trianElectrically controlled parabolic wavefront scanner in down-looking synthetic aperture imaging ladar (SAIL) is developed. The scanner is composed of electro-optic crystal and cylindrical lens with the advantages of small shape and high-speed. A linear phase modulation in electro-optic crystal is generated by four triangle electrodes. The systematical experiments confirm that the parabolic wavefront from the scanner agrees with the theoretical value well and is controlled accurately. The usefulness of the scanner is verified..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 828002 (2014)
Scattering
Modulating the Amplitude of Scattering light for Focusing
Sun Cunzhi, Chen Ziyang, and Pu Jixiong
Light will be scattered when passes through turbid media such as white paint or human tissue. It is of great significance for modulating and controlling the scattering light. The real-time amplitude modulation and feedback method is used to compensate the amplitude disorder produced by the turbid media. The light intenLight will be scattered when passes through turbid media such as white paint or human tissue. It is of great significance for modulating and controlling the scattering light. The real-time amplitude modulation and feedback method is used to compensate the amplitude disorder produced by the turbid media. The light intensity of a certain area can be strengthened by introducing a pre-modulation on the incident light. According to the real-time feedback data from the detector, the amplitude disorder can be better compensated by controlling the amplitude of light on certain area of the spacial light modulator. The experimental result showes that the modulated intensity can be 11 times that without modulation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 829001 (2014)
Spectroscopy
Measurement of Ethanol Vapor in Air with Tunable Diode Laser Absorption Spectroscopy
Geng Hui, Liu Jianguo, Zhang Yujun, Kan Ruifeng, Xu Zhenyu, Yao Lu, Ruan Jun, and Zeng Lizhong
The detection method for ethanol vapor concentrationin air based on tunable diode laser absorption spectroscopy is studied using narrow absorption peak in the vicinity of 7180 cm-1 (1393 nm) as an identification feature of ethanol molecule. To eliminate the interference of coexisting water vapor with the detection for The detection method for ethanol vapor concentrationin air based on tunable diode laser absorption spectroscopy is studied using narrow absorption peak in the vicinity of 7180 cm-1 (1393 nm) as an identification feature of ethanol molecule. To eliminate the interference of coexisting water vapor with the detection for ethanol vapor concentration in air, multidimensional linear regression analysis is applied to solve the problem of the coexistence of multiple molecule absorptions. A modification equation is promoted to resolve the problem of spectral error in the spectral data processing procedure, which is proved by experiments. The detection limit of integrated concentration is obtained by open-path measurement experiments as 30×10-6 m..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 830001 (2014)
Research on Grating Spectrum Reconstruction Based on Compressed Sensing and Its Application Characteristics
Jiang Shanchao, Wang Jing, Sui Qingmei, Lin Lanbo, Cao Yuqiang, and Wang Zhengfang
Based on the status that the existing grating spectrum demodulation methods require large amount of data which limited the data transformation and processing, compressed sensing is introduced to reconstruct high-precision grating spectrum through acquiring a few spectrum data. Fiber Bragg grating (FBG) and linearly chiBased on the status that the existing grating spectrum demodulation methods require large amount of data which limited the data transformation and processing, compressed sensing is introduced to reconstruct high-precision grating spectrum through acquiring a few spectrum data. Fiber Bragg grating (FBG) and linearly chirped fiber Bragg grating (LCFBG) are selected as the research objects. Grating spectrum FBG calibration experiment platform is built with tunable Fabry-Perot (F-P) filter demodulation algorithm (TFPDA) as the reference to validate the reconstructing practicability of compressed sensing. Gaussian nonlinear curve fitting is utilized to extract the center wavelengths reconstructed by TFPDA and compressed sensing under different temperatures. TBG temperature sensitivity coefficient obtained by compressed sensing is 20.3 pm/℃. Compared with the coefficient obtained by TFPDA, the relative error is 0.5%. Comparative analysis of LCFBG spectra collected by these two methods, the maximum error in 3 dB bandwidth is 1.03% and center wavelength is 0.69%. All these experimental results confirm that compressed sensing has certain application value in grating spectrum acquisition and reconstruction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 830002 (2014)
Thin Films
A New Approach to Eliminate Half-Wave Holes in Short-Wave Pass Filters with Layer Inhomogeneity
Bao Ganghua, Jiao Hongfei, Cheng Xinbin, Liu Huasong, and Wang Zhanshan
Short-wave pass filter is an important optical component in high power laser systems which has the repetitive structure of (0.5LH0.5L)N. But its optical property is significantly influenced by the half-wave hole due to layer inhomogeneity. Analysis by admittance theory shows the key reason for the presence of half-waveShort-wave pass filter is an important optical component in high power laser systems which has the repetitive structure of (0.5LH0.5L)N. But its optical property is significantly influenced by the half-wave hole due to layer inhomogeneity. Analysis by admittance theory shows the key reason for the presence of half-wave hole: the end point of the admittance locus of the periodic structure based on the quarter-wave stack doesn′t return to the initial point again. The greater the deviation, the worse the half-wave hole. By inserting matching layers between high and low index materials, a new method is presented to eliminate half-wave hole. The new short-pass film is designed and successfully fabricated, which has a super wide and smooth region with low reflectance at around second harmonic.The experimental results consistent well with the theoretical performance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 831001 (2014)
Design and Fabrication of a Near-Infrared Dichroic Beam Splitter Used for Space Laser Communication System
Zhang Qiuhui, Fu Xiuhua, and Liu Guojun
45° near-infrared dichroic beam splitter, with the spectrum 1530 nm transmitted and 1560 nm reflected, is designed and fabricated. Ta2O5 and SiO2 are selected as high and low refractive index materials. The structure of multiple cavity Fabry-Perot filter with 4H spacer is used to reduce the transitional region bet45° near-infrared dichroic beam splitter, with the spectrum 1530 nm transmitted and 1560 nm reflected, is designed and fabricated. Ta2O5 and SiO2 are selected as high and low refractive index materials. The structure of multiple cavity Fabry-Perot filter with 4H spacer is used to reduce the transitional region between transmittance and reflectance wavelength. The materials are evaporated by ion-assisted electron beam deposition, and optical monitoring method is used to control the thickness of each layer. The spectrum of the dichroic beam splitter is measured by spectrophotometer. The result shows that the optical energy transfer efficiency is higher than 92%, and the dichroic beam splitter is suitable for space laser communication system to separate different wavelength efficiently..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 831002 (2014)
Dispersive Properties of Optical Constants of Some Metallic Oxide Thin Films in the Mid-Infrared Regions
Liu Huasong, Ji Yiqin, Zhang Feng, Liu Dandan, Leng Jian, Wang Lishuan, Jiang Yugang, Chen Deying, Jiao Hongfei, Bao Ganghua, and Cheng Xinbin
Based on the application demands of metallic oxide thin films in the mid-infrared, the optical constants dispersion characteristics of four kinds of metallic oxide films of TiO2, HfO2, Ta2O5 and Y2O3 in the mid-infrared (2.5~5 μm) region in moisture state are studied, the four kinds of metallic oxide films are preparedBased on the application demands of metallic oxide thin films in the mid-infrared, the optical constants dispersion characteristics of four kinds of metallic oxide films of TiO2, HfO2, Ta2O5 and Y2O3 in the mid-infrared (2.5~5 μm) region in moisture state are studied, the four kinds of metallic oxide films are prepared on the super polishing silicon substrates using electron beam evaporation deposition technology, and based on the Lorentz oscillator dielectric constant dispersion model, the optical constants of the four kinds of oxide thin films are calculated using the transmittance spectra inversion method. The results show that all the four kinds of oxide films have a small amount of water molecules and hydroxyl. In increasing order of water content of these films are TiO2, HfO2, Ta2O5 and Y2O3, and far away from the location of the water absorption, in increasing order of extinction coefficient of these films are TiO2, HfO2, Ta2O5 and Y2O3. In order to reduce the effects of water absorption, TiO2 and HfO2 are the comparative ideal metallic oxide materials in the mid-infrared region under the condition of the electron beam evaporation deposition process..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 8, 831003 (2014)
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