Contents
2010
Volume: 30 Issue 10
54 Article(s)
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Research Article
Atmospheric Optics and Oceanic Optics
Simulation of the Profile Distribution of Water-Leaving Radiation Contribution in Taihu Lake in Winter and Summer
Zhao Qiaohua, and Qiu hui
Based on the measured scattering and absorption coefficient at fifty points in Taihu lake in winter and summer, the profile distribution of water-leaving radiation contribution and the depth of the same contribution of water-leaving radiation at different point in Taihu lake are simulated by multiple scattering models Based on the measured scattering and absorption coefficient at fifty points in Taihu lake in winter and summer, the profile distribution of water-leaving radiation contribution and the depth of the same contribution of water-leaving radiation at different point in Taihu lake are simulated by multiple scattering models assurning that the radiation field has no internal light source, no inelastic scattering and the water is uniformly mixed. The results show that, the depth for the sum of water-leaving radiation contribution reaching 99.5% (accumulated downward from the surface) has significant difference in different space on the account of wind wave action and the concentration of phytoplankton in winter and in summer. In summer, the smallest depth is in Meiliang bay and Zhushan bay, followed by the center of the lake and Gonghu bay, in the south-east of Taihu lake the depth is the biggest and the contribution of sediments reflection in east Taihu lake and Xishan hills can not be ignored. In winter, the sediments reflection need to doesn′t be considered since the depth for the sum of water-leaving radiation contribution reaching 99.5% is less than the water depth. In Meiliang Bay, Zhushan Bay, western coast, Gonghu Bay, east Taihu Lake and Xishan Hills the depth is relatively large, but not more than 450 mm. In summer the suspended particulate and chlorophyll are the mainly factors which effected the depth, in winter the mainly factor is suspended particle. The spatial inhomogeneous distribution of the interior water body optical characters determins the spatial difference of the water-leaving radiation contribution which is caused by the upward radiation due to the different depth scattering. Coupling the profile distribution of water-leaving radiation contribution has a great improvement on remote sensing of the quality parameters of water Ⅱ..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2821 (2010)
Comparison of Remote Sensing Aerosol Optical Depth from MODIS Data with In-Situ Sky Radiometer Observations Over East China Sea
Li Dong, and Chen Wenzhong
The in-situ data of sky radiometer observed on ship at East China Sea during five cruises from April 2006 to November 2007 are used to validate the corresponding 869 nm aerosol optical depth data included in MODIS standard ocean color products. The spatial box of 10 km×10 km and temporal interval of ±1 h are The in-situ data of sky radiometer observed on ship at East China Sea during five cruises from April 2006 to November 2007 are used to validate the corresponding 869 nm aerosol optical depth data included in MODIS standard ocean color products. The spatial box of 10 km×10 km and temporal interval of ±1 h are used as the matching criterion. The results show that: 72% of the match-up data fall close to, or within the expected error range of Δτ＝±0.03±0.05τ. As there are some differences in the precision of MODIS-derived aerosol optical depth according to regions and seasons, data consistency over the East China Sea is better than the Yellow Sea, while the consistency in the winter of 2006 is better than the fall of 2007. In the fall of 2007, MODIS retrieval values are systematically overestimated. The reason for this phenomenon was analyzed. It seems that twelve pre-calculated aerosol models used by MODIS retrieval algorithms can′t match the optical properties of the actual aerosol very well, and further analysis with all of match-up data confirmed the conclusion..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2828 (2010)
Experimental Study of Satellite Retrieval of Dust Aerosol Optical Thickness Using AERONET SACOL Site Observations
Bai Hongtao, Feng Jiandong, Chen Yonghang, Huang Jianping, Zhang Wu, Kang Yanming, and Pan Hu
Employing the 6S atmospheric radiation transport model and Terra moderate-resolution imaging spectroradiometer (MODIS) L1B data, the experimental retrieval of dust aerosol optical thickness is performed using surface reflectance atmospheric correction and dust aerosol model built with aerosol observations at Semi-arid Employing the 6S atmospheric radiation transport model and Terra moderate-resolution imaging spectroradiometer (MODIS) L1B data, the experimental retrieval of dust aerosol optical thickness is performed using surface reflectance atmospheric correction and dust aerosol model built with aerosol observations at Semi-arid Climate and Environment Observatory of Lanzhou University (SACOL). The results show that the four schemes of regional algorithm are feasible. The retrieval result derived from the atmospheric correction scheme using the aerosol model built by SACOL data with consideration for the ngstrm exponent is closest to the surface observation. The relative error is -7.3%. The quantitative analysis of error using a numerical test is performed and the results show that the retrieval is stable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2837 (2010)
Propagation Equation of the Effective Radius of Curvature of General Beams
Ji Xiaoling
The propagation equation of the effective radius of curvature of general beams in atmospheric turbulence and free space is given, and the formula of the position where the effective radius of curvature reaches its minimum is also derived. The properties of the effective radius of curvature are studied analytically, andThe propagation equation of the effective radius of curvature of general beams in atmospheric turbulence and free space is given, and the formula of the position where the effective radius of curvature reaches its minimum is also derived. The properties of the effective radius of curvature are studied analytically, and illustrated by numerical calculation examples. It is shown that the effective radius of curvature of general beams obeys the same free-space propagation equation as the wavefront curvature of an ideal Gaussian beam. In free space the wavefront of general beams can be regarded as a spherical surface when the propagation distance is long enough. However, in turbulence the effective radius of curvature of general beams depends on the beam parameters when the propagation distance is long enough, and the effective radius of curvature decreases when the strength of turbulence-increases..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2845 (2010)
Diffraction and Gratings
Wave-Front Quality Analysis of Three-Dimension Pinhole Vector Diffractional in Extreme Ultraviolet Region
Lu Zengxiong, Jin Chunshui, Zhang Lichao, and Wang Liping
The quality of the reference wave front in phase shifting point diffraction interferometer depends on the pinhole diameter, roundness and thickness, where the first one is the most critical factor. The requirement for pinhole diameter should be known before the manufacture in actual maching. Three-dimensional pinhole dThe quality of the reference wave front in phase shifting point diffraction interferometer depends on the pinhole diameter, roundness and thickness, where the first one is the most critical factor. The requirement for pinhole diameter should be known before the manufacture in actual maching. Three-dimensional pinhole diffraction is calculated based on the vector diffraction theory. How the pinhole diameter affects the diffracted wave-front quality is analyzed under the uniform incident light with TE and TM polarization. The appearance of the astigmatism and coma in the wave front is brought about by the linear polarization of incident light. The calculation and analysis show that in order to obtain reference wave front with 0.1 numerical aperture (NA), the root mean square of (RMS) wave-front error below 0.005 λ (λ=13.55 nm), together with 0.4 intensity uniformity, for a 90 nm thickness pinhole, the diameter of 70 nm is suitable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2849 (2010)
Fiber Optics and Optical Communications
High-Precision Transverse-Pressure Sensing System Utilizing Mechanically-Induced Long-Period Fiber Grating
Jiang Mingshun, Feng Dejun, and Sui Qingmei
A high precision transverse pressure sensing system using mechanically-induced long period fiber gratings(MLPFG), is designed and studied experimentally. 60 mm-long periodic pressure grooves are made by mechanical line processing technology with the groove period of 600 μm. The relation between transverse pressure and A high precision transverse pressure sensing system using mechanically-induced long period fiber gratings(MLPFG), is designed and studied experimentally. 60 mm-long periodic pressure grooves are made by mechanical line processing technology with the groove period of 600 μm. The relation between transverse pressure and MLPFG resonance peak is measured. Furthermore, a demodulation system is constructed employing a fiber Bragg grating(FBG), the results show that MLPFG transverse pressure has good linear relation with MLPFG resonance peak in the range of 0～60 N. Linearity is up to 0.9950 and the sensitivity is about 0.35 dB/N. Keeping the MLPFG transverse pressure 45 N for more than 20 h, the MLPFG resonance peak′s maximum fluctuation is less than 0.06 dB. The FBG with central-wavelength at 1542.890 nm is adopted to realize system demodulation, the system sensitivity is 0.12 μW/N, and the practicality of detecting system is further improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2855 (2010)
Analysis on Error Rate of Wireless Optical Communication Using Subcarrier Modulation on Turbo Code
Chen Dan, and Ke Xizheng
Optical wireless communication based on the log-normal model under the turbulence channel was introduced. Combining the characteristics of atmospheric channel, we analyzed the error rate of atmospheric laser communication using several kinds of subcarrier modulation system is analyzed. Under different scintillation disOptical wireless communication based on the log-normal model under the turbulence channel was introduced. Combining the characteristics of atmospheric channel, we analyzed the error rate of atmospheric laser communication using several kinds of subcarrier modulation system is analyzed. Under different scintillation distribution, the error rate of wireless optical communication using subcarrier modulation on turbo code was analyzed, and the bit error rate (BER) performance between Turbo coded and uncoded systems was compared. The simulation results showed that the error performance of binary phase shift keying (BPSK) was better than others, and turbo coded is efficient to improve jamming-rejection capability of system with the low signal-noise ratio (SNR) and strong scintillation index..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2859 (2010)
Study on 90° Docking Error Control in Polarization Maintaining Fiber Resonator of Resonant Fiber Optic Gyroscope
Lin Huizu, Yao Qiong, and Hu Yongming
Polarization fluctuation in polarization maintaining fiber (PMF) resonator caused by cross-polarization coupling is one of the major noise sources in resonant fiber optic gyroscope. Polarization axis 90° butt joint is an effective way to overcome the polarization fluctuation, and the size of butt docking error hasPolarization fluctuation in polarization maintaining fiber (PMF) resonator caused by cross-polarization coupling is one of the major noise sources in resonant fiber optic gyroscope. Polarization axis 90° butt joint is an effective way to overcome the polarization fluctuation, and the size of butt docking error has important effect on the gyroscope noise suppression effects. The 90° butt joint error control of double-coupler PMF resonator based on Mickelson white-light interfero meter is studied theoretically and obtains the interference formula of polarization mode, and then the butt joint error degree. Finally, 90° docking error control in two-coupler PMF resonator is studied in experiment, and the experimental butt joint error of 0.37° is obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2864 (2010)
Self-Assembly of Colloidal Microspheres on the Cylindrical Substrate of Optical Fibers
Guo Wenhua, Wang Ming, Liu Qing, Xia Wei, and Dai Lihua
A standard single-mode silica optical fiber is selected as an ideal cylindrical substrate for the three-dimensional colloidal crystal coated with silica microspheres through isothermal heating evaporation induced self-assembly at certain temperature and liquid surface dropping velocities. The optical fiber is verticallA standard single-mode silica optical fiber is selected as an ideal cylindrical substrate for the three-dimensional colloidal crystal coated with silica microspheres through isothermal heating evaporation induced self-assembly at certain temperature and liquid surface dropping velocities. The optical fiber is vertically inserted into the silica microspheres colloidal solution at the center of the vial, and three-dimensional nanostructures colloidal crystal film is fabricated by capillary force. The silica spheres used have an average diameter of 390 nm. It takes only 12 h for the sphere particles to completely form crystal film. The photonic crystal cylindrical annulus is characterized by scanning electron microscopy (SEM). Scanning electron micrographs illustrate the ［111］ and ［100］-oriented regions, and the two zones of regularly intercrossed pattern. Qualitative analysis and discussion are carried out for the the different alignment of crystal orientation of sililca micro-spheres and the cross pattern..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2869 (2010)
Phase Control of Coherent Fiber Laser Array Using Stochastic Parallel Gradient Descent Algorithm and its Application
Wang Xiaolin, Zhou Pu, Ma Yanxing, Ma Haotong, Xu Xiaojun, and Zhao Yijun
Active phasing coherent beam combination of fiber laser array is an efficient way to scale high power laser while holding good beam quality simultaneously. The key technique of active phasing coherent beam combining system is active phase-locking control of the coherent fiber laser array. Active phase-locking using stoActive phasing coherent beam combination of fiber laser array is an efficient way to scale high power laser while holding good beam quality simultaneously. The key technique of active phasing coherent beam combining system is active phase-locking control of the coherent fiber laser array. Active phase-locking using stochastic parallel gradient descent (SPGD) algorithm holds the advantage of easy strategy and compact bulk. Furthermore, by choosing appropriate metric function and iteration parameter, special phase control state of the system can be realized and corresponding multiform coherent combined laser beams can be achieved, which are agree with the requirement of adaptive photonics phase-locked element (APPLE) array system. With SPGD algorithm-based active phase-locking system, in-phase phase locking of coherent beam combination, beam steering of the main lobe of combined laser beams, generation of dark-hollow beam are analyzed theoretically and demonstrated experimentally, and the feasibility of multiform beam control of coherent fiber laser array using SPGD algorithm is validated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2874 (2010)
The Research on OCDMA Encoder/Decoder Based on Photonic Crystal Waveguides
Li Chuanqi, Chen Hui, Zhou Xu, Zhao Lilong, Song Biao, and Sun Tingting
The mechanism of a new optical function device——photonic crystal (PC) filter is discussed. Subsequently, the basic theory for encoder/decoder in optical code division multiple access (OCDMA) system based on multiple channel PC filter consisting of band-pass filter and band-stop filter is proposed. Light signals are divThe mechanism of a new optical function device——photonic crystal (PC) filter is discussed. Subsequently, the basic theory for encoder/decoder in optical code division multiple access (OCDMA) system based on multiple channel PC filter consisting of band-pass filter and band-stop filter is proposed. Light signals are divided into several chips by the defect resonate cavity to encode/decode the user signals in frequency domain, according to the coupled-mode theory. Thus, the decoder in 2D-OCDMA can be performed. A waveguide decoder/encoder in OCDMA system consisting of three-channel photonic crystal filter, whose wavelength centered at 1527.70, 1551.10, 1570.00 nm is designed. To elevate the transmission efficiency, an extra defect is attached in at the sideway of the bus waveguide. As a results, the efficiency of the second chip is up to 95%. In emulation, the full width at half maximum is 0.3 nm, so there won′t be interference between signals in each channel. Also, energy loss in the process of decoding/encoding by PC waveguide encoder/decoder is small, which plays an important part in remote communication..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2879 (2010)
Image Processing
Dynamic 3D Reconstruction and Pipelined 3D Modeling Based on Stripe Boundary Encoding
Guo Jiping, Peng Xiang, Liu Xiaoli, Li Ameng, and Yin Yongkai
An approach for dynamic 3D shape acquisition of moving object and pipelined 3D modeling is proposed. Based on a brief review of previously reported methods a modified sensor prototype to realize the proposed approach is designed, which relies on color stripe boundary encoding. By locating the ghost boundary and removinAn approach for dynamic 3D shape acquisition of moving object and pipelined 3D modeling is proposed. Based on a brief review of previously reported methods a modified sensor prototype to realize the proposed approach is designed, which relies on color stripe boundary encoding. By locating the ghost boundary and removing its influence on boundary tracking, it is possible to reduce the erroneous range data and improve the scanning efficiency. Moreover, an efficient method for pipelined 3D modeling based on the registration using markers is proposed. An interactive view planning method in the modeling is also presented, leading to an improved accuracy and efficiency for registration and resulting in a modeling process with minimum range images. Experiment results show that the proposed approach can not only reconstruct the range image of single viewpoint accurately, but also automatically register the range images from different viewpoints, achieving 3D modeling in a pipeline mode..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2884 (2010)
Modulation Transfer Function Calculation and Image Restoration Based on Slanted-Edge Method
Li Tiecheng, Tao Xiaoping, Feng Huajun, and Xu Zhihai
The modulation transfer function (MTF) is one of the key indicators characterizing the signal transfer characteristics of an imaging system as a function of spatial frequency in terms of linear response theory. Various methods have been proposed to determine the MTF of an imaging system which is based on point, slit orThe modulation transfer function (MTF) is one of the key indicators characterizing the signal transfer characteristics of an imaging system as a function of spatial frequency in terms of linear response theory. Various methods have been proposed to determine the MTF of an imaging system which is based on point, slit or edge images. The slanted-edge method to calculate the MTF is used. The method is modified to correct the bias caused by sensor and calculation procedure. The designed MTF, measured MTF, and calculated MTF have all been utilized to restore the remote sensing images by MTF compensation. All of the improved images are compared and the result verifies the effectiveness and reliabilities of the calculated MTF in the restoration of the degraded images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2891 (2010)
K-Edge Digital Subtraction X-Ray Imaging for Observation of Cu2+ Adsorption in Polymer Particles
Guo Rongyi, Ma Hongjuan, Xue Yanling, Xie Honglan, Deng Biao, Du Guohao, Wang Min, and Xiao Tiqiao
The investigation and development of novel functional organic material for the adsorption of heavy metal ion in water is one of the important solutions to water pollution. However, with traditional techniques, it is very difficult to observe directly the distribution of heavy metal ion inside the adsorptive material. BThe investigation and development of novel functional organic material for the adsorption of heavy metal ion in water is one of the important solutions to water pollution. However, with traditional techniques, it is very difficult to observe directly the distribution of heavy metal ion inside the adsorptive material. By means of the tunability and penetrability of the X-rays, this problem is researched with K-edge digital subtraction (KES) imaging. Systematical investigation is carried out successfully, resorting to optimization for experimental conditions, image registration and median filtering etc.. The experimental results demonstrate that the adsorbed copper ions can infiltrate into the adsorber. The results also indicate that sizes of the adsorbing particles do not have obvious impact on the infiltrating depth of the copper ions. The mass of the copper ions adsorbed per unit time is mainly affected by the superficial area..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2898 (2010)
Extracting Straight Lines from Building Image Based on Edge Orientation Image
Ding Weili, Wang Wenfeng, Zhang Xuguang, and Su Liancheng
Detecting lines in a digital image is a crucial step in many applications, such as visual navigation, feature recognition and remote sensing image processing, In this paper, an algorithm which is based on edge orientation image is proposed for extracting straight lines from comples building image. Firstly, edges are deDetecting lines in a digital image is a crucial step in many applications, such as visual navigation, feature recognition and remote sensing image processing, In this paper, an algorithm which is based on edge orientation image is proposed for extracting straight lines from comples building image. Firstly, edges are detected based on Canny detector. Secondly, an edge direction coding strategy is proposed by detecting the local line in 9×9 window. Thirdly, edges are split into a series of straight lines, curves and points, and a new secondary image — the edge orientation image is generated. Finally, the straight lines are extracted from the edge orientation image by analyzing the direction distribution, and using the straightness errors evaluation strategy and the sparse line fitting algorithm. Experiment results show that the proposed algorithm is better than hough transform and phase grouping algorithm. It can detect lines correctly in complex building images with high accuracy rate, low false and low missing rate and good robustness..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2904 (2010)
Imaging Systems
Effects of Detector Size and Defocusing Length on Lensless Ghost Diffraction
Lin Jie, and Cheng Jing
Recently, ghost imaging with thermal light attracts a lot of attention both theoretically and experimentally. The effects of the detector size and defocusing length on lensless ghost diffraction are investigated. Through analyzing the intensity correlation function of lensless ghost diffraction, the defocusing will leaRecently, ghost imaging with thermal light attracts a lot of attention both theoretically and experimentally. The effects of the detector size and defocusing length on lensless ghost diffraction are investigated. Through analyzing the intensity correlation function of lensless ghost diffraction, the defocusing will lead to a chirp modulation on the phase of the transmission function of the object, while the finite size of the detector makes the lensless ghost diffraction system equivalent to a partially coherent imaging system. These effects lead to the degradation of the imaging quality. Via calculating the correlation of the idealized images and realistic images under different conditions, the dependences of diffraction qualitites on different parameters are quantitatively analysed, so that the results may be used to provide quantitative references for realistic experiments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2912 (2010)
Instrumentation, Measurement and Metrology
Speckle Correlation Used in Measurement of Elliptical Gaussian Beam Divergence
Huang Zhanhua, Zhu Meng, Cai Huaiyu, and Zhang Yinxin
Divergent angle of laser beam which used in laser guidance and measurement is an important parameter. Large area illumination of laser is also an important application in large-scale speckle interferometry. The relation between speckle size and elliptical Gaussian laser beam illumination parameter is derived by using sDivergent angle of laser beam which used in laser guidance and measurement is an important parameter. Large area illumination of laser is also an important application in large-scale speckle interferometry. The relation between speckle size and elliptical Gaussian laser beam illumination parameter is derived by using speckle auto-correlation, and the effective two-dimensional lighting size at receiving plane is calculated, the divergence according to the lighting sizes at different distances futhermore determined. This device is simply constructed. Using laser speckle auto-correlation metrology methods the dynamic range of laser intensity is enlarged, ignoring the off-axis influence, and environmental light is suppressed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2918 (2010)
A New Calibration Method of Systematic Errors in Phase-Shifting Point Diffraction Interferometer
Liu Ke, and Li Yanqiu
Because the phase-shifting point diffraction interferometer (PS/PDI) uses lateral shearing of test and reference waves to generate carrier frequency fringe pattern, significant systematic measurement errors are consequentialty introduced. A new calibration method of PS/PDI systematic errors, named rotating grating methBecause the phase-shifting point diffraction interferometer (PS/PDI) uses lateral shearing of test and reference waves to generate carrier frequency fringe pattern, significant systematic measurement errors are consequentialty introduced. A new calibration method of PS/PDI systematic errors, named rotating grating method, is proposed. Based on the PS/PDI measurement results obtained with two gratings in orthogonal directions, the proposed method utilizes the orthogonal and symmetric property of Zernike polynomials in unit circle to calibrate the systematic errors of PS/PDI. The calibration experiment of visible light PS/PDI is performed to verify the method. The result shows that the geometric coma of the system is －0.116 λ which is consistent with the theoretical value of －0.133 λ, which proves the validity of the method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2923 (2010)
All-Phase Fourier Transfrorm Spectrum Analysis
Jia Fangxiu, Ding Zhenliang, Yuan Feng, and Ge Dongsheng
The traditional laser range finder cannot meet the need of real-time, high-resolution measurement because of its low anti-jamming capability and time-consuming measurement. Owing to this, multi-channel transmitting and receiving system for phase-shift laser range finder based on parallel digital signal processor (DSP) The traditional laser range finder cannot meet the need of real-time, high-resolution measurement because of its low anti-jamming capability and time-consuming measurement. Owing to this, multi-channel transmitting and receiving system for phase-shift laser range finder based on parallel digital signal processor (DSP) was designed. Multi-frequency modulation laser can be transmitted and received at the same time, whish improves the measurement speed and avoids the wrong data fusion because of target moving. A new frequency correction method was proposed according to the amplitude spectrum acquired by all-phase FFT, amplitude spectrum is expanded into Taylor series and the correction value of frequency is calculated by relation of spectral lines. Monte-Carlo simulation results proved that the new frequency correction method had higher resolution and better stability than Rife method and centro-baric method. In experiments, the sampling frequency of AD converter is 937.5 kHz, the all-phase FFT transform point number is 1024, the phase difference resolution better than 0.003° and the frequency resolution better than 0.033 Hz are obtained. Experiments proved that the system can meet the need of high-accuracy, real-time distance measurement of moving target..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2928 (2010)
Research on Detection Sensitivity of Space-Based Visible Sensor
Pan Haibin, Song Guanghua, Xie Lijun, Zhu Bo, He Lisha, and Zheng Yao
Along with the development of remote sensing technique, performance demands of load become higher and higher. Especially the detection sensitivity of load is related to the ability of detecting target. How to meet and increase detection sensitivity of load is becoming a problem of developing high-performance remote senAlong with the development of remote sensing technique, performance demands of load become higher and higher. Especially the detection sensitivity of load is related to the ability of detecting target. How to meet and increase detection sensitivity of load is becoming a problem of developing high-performance remote sensing device. Based on the theories of photometry and radiometry, space target detection signal intensity is analyzed and calculated. According to classical detection theory, the model of detection sensitivity of space-based visible (SBV) sensor is derived based on the mathematical expression of target and noise. By substituting American SBV sensor parameters into the model, the error between calculation result (15.55 visual magnitude) and design specification (15.5 visual magnitude) of detection sensitivity is only 0.05 visual magnitude. This shows that the detection sensitivity model has considerable accuracy, and will provide a theoretical reference for space-based visible sensor research and design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2935 (2010)
Influence of Mode Pulling Effect on Beat Frequency in Dual-Frequency He-Ne Laser
Wang Zhiguo, Long Xingwu, Liang Jing, and Wang Fei
In order to improve beat frequency stability in the dual-frequency laser with piezoelectric transducer for frequency stability, various error factors were analyzed, and with special attention on mode pulling effect. Due to mode pulling effect, beat frequency stability was influenced by path length, gain and temperatureIn order to improve beat frequency stability in the dual-frequency laser with piezoelectric transducer for frequency stability, various error factors were analyzed, and with special attention on mode pulling effect. Due to mode pulling effect, beat frequency stability was influenced by path length, gain and temperature. When an ordinary power supply was used, the beat frequency stability of the laser was 4.5×10-8 in a constant temperature room. When a high-stability power supply was used, the beat frequency stability was 1.2×10-9. Beat frequency has relation between current and temperature was obtained, which also showed gain and temperature had important influence on beat frequency. Therefore, in order to obtain high beat-frequency stability in the dual-frequency lasers, variations of path length, current and temperature should be reduced..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2941 (2010)
Absolute Distance Measurement by Using 117 μm Synthetic Wavelength
Liang Jing, Long Xingwu, Zhang Bin, and Jin Shilong
To overcome the defects of large error in two-longitudinal-mode wavelengths interferometer for absolute distance measurement, a new kind of multi-wavelength absolute distance interferometer is introduced. A double-mode 633 nm He-Ne laser and a 629 nm He-Ne laser are employed to generate 117 μm synthetic wavelength, witTo overcome the defects of large error in two-longitudinal-mode wavelengths interferometer for absolute distance measurement, a new kind of multi-wavelength absolute distance interferometer is introduced. A double-mode 633 nm He-Ne laser and a 629 nm He-Ne laser are employed to generate 117 μm synthetic wavelength, with which distance with high precision is measured by using the double heterodyne interferometric technique. The static and dynamic experiments show that due to the shorter synthetic wavelength, the uncertainty can reaches 3.8×10-6L+57 nm and the error is 2 μm within 500 mm. From the uncertainty of synthetic wavelength, the error of the new interferometer is also discussed. The interferometer could measure distance with high precision if coupled with two-longitudinal-mode beat measurement system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2947 (2010)
Lasers and Laser Optics
Building and Effect Evaluation of Multi-Beam Coherent Combining Control Model
Yang Yuchuan, Jing Feng, Li Fuquan, Wang Xiao, Huang Xiaojun, Feng Bin, and Luo Hui
A coherent beam combining model with 2×2 segment mirrors is developed with a 3D adjustment including 2D rotation and 1D translations to realize phase lock between individual beams for the higher output power. The combining model is simulated using ray tracing and diffraction method, and the accuracy of adjusting pA coherent beam combining model with 2×2 segment mirrors is developed with a 3D adjustment including 2D rotation and 1D translations to realize phase lock between individual beams for the higher output power. The combining model is simulated using ray tracing and diffraction method, and the accuracy of adjusting parameters with rotations of ±0.5 μrad and translation of ±105.3 nm are obtained. Considering the adjusting tolerance, the system performance is estimated by Monte-Carlo error analysis for flat wavefront and non-flat wavefront. The power ratio within 20 μm diameter spot in symmetrical layout is statistically analyzed compared with that in asymmetrical layout. The results show that the symmetrical layout is effectively beneficial to raise output power level of large-scale high-power solid-state laser by coherent combining..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2952 (2010)
Experimental Study on Non-Boiling Heat Transfer with Air-Assist Atomization for High-Power Laser
Si Chunqiang, Xu Hongbo, Tang Mingsheng, and Tian Changqing
Keeping the heat flux density and the temperature of water at inlet constant, cooling experiments on non-boiling heat transfer with air-assist atomization are carried out. The influences of liquid mass flow rate and pressure, air to liquid ratio and nitrogen pressure on sauter diameter dSMD are analyzed. The heat transKeeping the heat flux density and the temperature of water at inlet constant, cooling experiments on non-boiling heat transfer with air-assist atomization are carried out. The influences of liquid mass flow rate and pressure, air to liquid ratio and nitrogen pressure on sauter diameter dSMD are analyzed. The heat transfer capacity and temperature uniformity are further studied respectively. The results show that when the air-liquid mass flow ratio is above 5%, the same nitrogen and liquid pressure can get a better heat transfer due to optimal match of gas-liquid relative velocity, the nitrogen kinetic energy utilization and gas consumption rate, and as the liquid pressure is slightly lower than the nitrogen pressure uniform temperature distribution can be achieved. When the air-liquid mass flow ratio is below 5%, a better heat transfer and temperature distribution can be gotten under the condition of the nitrogen pressure slightly higher than the liquid pressure, which ensure the utilization of gas kinetic energy while increase the relative velocity and optimize the droplet atomization and distribution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2958 (2010)
Study of a Diode-Pumped Actively Q-Switched Nd:YAG Ceramic 1319 nm Laser
Li Ping, Chen Xiaohan, Wang Qingpu, and Zhang Xingyu
An efficient diode-pumped actively Q-switched Nd:YAG ceramic laser operating at 1319 nm was demonstrated. At an incident pump power of 23.7 W, average output power of 4.8 W at pulse repetition frequency of 30 kHz and pulse duration of 110 ns was obtained. The corresponding optical-to-optical conversion efficiency is 20An efficient diode-pumped actively Q-switched Nd:YAG ceramic laser operating at 1319 nm was demonstrated. At an incident pump power of 23.7 W, average output power of 4.8 W at pulse repetition frequency of 30 kHz and pulse duration of 110 ns was obtained. The corresponding optical-to-optical conversion efficiency is 20.3%. A maximum single pulse energy of 316 μJ with a pulse duration of 78.5 ns is obtained at incident pump power of 19.4 W at pulse repetition frequency of 10 kHz..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2963 (2010)
Materials
Well Width Dependence of Band Gap Renormalization of Single ZnO/MgZnO Quantum Well
Li Xiaolong, Jiang Xiaofang, Lei Xiaoyan, Qiu Zhiren, Zhang Baoping, Ding Cairong, and Zeng Xueran
Band gap renormalization of ZnO/Mg0.1Zn0.9O single quantum well (QW) with gradual well width (Lw) is studied by room-temperature time integrated photoluminescence (PL) spectra at high excitation power density. The photo-generated carrier density is n=1.6×1014 cm-2 and the magnitude of red shift of PL spectrum peakBand gap renormalization of ZnO/Mg0.1Zn0.9O single quantum well (QW) with gradual well width (Lw) is studied by room-temperature time integrated photoluminescence (PL) spectra at high excitation power density. The photo-generated carrier density is n=1.6×1014 cm-2 and the magnitude of red shift of PL spectrum peak increases from 5.9 meV to 97.1 meV with Lw changing from 2.3 nm to 4.3 nm. With Lw increaseing, the red shift increases but the increase rate gradually decreases. When Lw>2αB(αB, the exciton Bohr radius of ZnO bulk, is about 2 nm)， the red shift starts to be gradually saturated. It is found that the red shift is the competition result of energy gap contraction due to many body effect and intraband filling effect at high excitation power density. The result is useful for designing and application of ZnO QW-based optoelectronic devices..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2967 (2010)
Transversal Electro-Optic Effect of Light Propagating in Arbitrary Direction in LiNbO3
Su Shida, Wan Lingyu, Zhou Yu, Sun Jianfeng, and Liu Liren
Transversal electro-optic effect of light propagating in arbitrary direction in LiNbO3 is studied based on the index ellipsoid equation. The characteristics of inductive refractive index of crystal in different directions are investigated. When the electric field is applied along y axis, besides light propagating alongTransversal electro-optic effect of light propagating in arbitrary direction in LiNbO3 is studied based on the index ellipsoid equation. The characteristics of inductive refractive index of crystal in different directions are investigated. When the electric field is applied along y axis, besides light propagating along the c axis, for the cases of light propagating in the c-y or c-x plane, the inductive refractive index is linearly proportional to the applied electric field and the linear curves are different in different propagation directions. In other cases, the inductive refractive index and the applied electric field have different curves of nonlinear variation in different directions. When the electric field is applied along x axis, the inductive refractive index has the similar characteristics. But the propagating directions holding linear relation are related to the c axis by a 45°rotation. The results will be helpful to the new applications of electro-optic effect of LiNbO3 crystal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2972 (2010)
Research of Passivation and Anti Reflecting Layer on GaN Based Blue LED on Silicon Substrate
Liu Junlin, Qiu Chong, and Jiang Fengyi
SiON passivation layer is deposited on GaN blue LED based on Si substrate. It improves the light output power of LED by 12% and reduces the luminous decay of LED during aging efficiently. The analysis results of the samples with and without SiON passivation layer demonstrate that SiON layer can separate the epoxy from SiON passivation layer is deposited on GaN blue LED based on Si substrate. It improves the light output power of LED by 12% and reduces the luminous decay of LED during aging efficiently. The analysis results of the samples with and without SiON passivation layer demonstrate that SiON layer can separate the epoxy from hot surface of LED during aging, which prevents epoxy resin from carbonization. In addition, the SiON layer can partly relax tensile stress of device from epoxy resin, and reduce the generation probability of non-radiation centers. Furthermore, SiON layer can reduce sidewall leakage current of LED. In a word, SiON layer can improve the stability of LED..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2978 (2010)
Optical Properties of Coumarin 102 Incorporated in Sol-Gel Mesoporous Aluminum Phosphate Glass
Li Rihong, Fan Youyu, Fan Jintai, and Zhang Long
Mesoporous AlPO4 glass with high surface area is prepared with new sol-gel processing, followed by incorporating coumarin 102 with dipping method. The effects of coumarin 102 concentration on the optical properties of AlPO4 glass and molecular formation of coumarin 102 are studied by excitation spectra and emission speMesoporous AlPO4 glass with high surface area is prepared with new sol-gel processing, followed by incorporating coumarin 102 with dipping method. The effects of coumarin 102 concentration on the optical properties of AlPO4 glass and molecular formation of coumarin 102 are studied by excitation spectra and emission spectra methods. The main excitation band placed at 366 nm is ascribed to monomeric coumarin 102 in excitation spectra, and the main excitation band is broadened due to the aggregating of fluorescent dimers in the mesoporous glass as coumarin 102 concentration increases from 5×10-6 mol/L to 5×10-3 mol/L. Red shift of emission band from 459 nm to 479 nm is observed in emission spectra as coumarin 102 concentration increases from 5×10-6 mol/L to 5×10-3 mol/L. The tunable width is 135 nm when the concentration is 5×10-3 mol/L. The stability of the coumarin 102 absorbed in the AlPO4 mesoporous glass is investigated by bleaching experiment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2983 (2010)
New Mid-Infrared Oxyfluoride Glass and Technique Utilizing Radar Latent Functionality
Che Hong, Fan Youyu, Yang Yi, Yuan Xinqiang, Tang Bin, Li Jiacheng, Jiang Xiongwei, and Zhang Long
Infrared-transparent glass is one of the key window materials for some important military applications. It′s still a great challenge to fabricate the infrared-transparent glass with high-properties and large size. With the great development of infrared technology and electro-optical countermining technique, the infrareInfrared-transparent glass is one of the key window materials for some important military applications. It′s still a great challenge to fabricate the infrared-transparent glass with high-properties and large size. With the great development of infrared technology and electro-optical countermining technique, the infrared windows with the capacity of radar latent and electro-magnetic shielding (EMS) are essentially required. In this paper, our philosophy is demonstrated to face the challenge in making infrared glass with high-properties and large size, and a new mid-infrared gallium oxyfluoride (FGa) glass is deveosped. Based on FGa glass, some new EMS techniques are developed to make the infrared-windows radar latent..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2988 (2010)
Medical Optics and Biotechnology
Hand Shape Verification Method Based on Hand Geometry Feature
Yuan Weiqi, and Dong Qian
A method for personal identification based on hand geometric feature according to the measurable characteristic of hand shape is presented. Firstly feature points are localized by using curvature, according to which the absolute length of some parts of hand can be calculated. Then an eigenvector composed of relative leA method for personal identification based on hand geometric feature according to the measurable characteristic of hand shape is presented. Firstly feature points are localized by using curvature, according to which the absolute length of some parts of hand can be calculated. Then an eigenvector composed of relative lengths is obtained. The relative lengths in the eigenvector are generated from the absolute lengths of some parts of hand. At last, personal identification is achieved by computing Euclidean distance between eigenvectors. In the experiment, the accurate recognition rate is 91.08% by using only five characters, and 93.27% when the character number used to identify is 11. The experimental results show that, personal identification can be achieved by using the relative length of hand geometric feature. It can reach a high recognition rate only by use a few characters using the method proposed, and the method is easy to realize with characteristic of high utility..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2994 (2010)
Nonlinear Optics
(1+1)-D Breathers Solution in Nematic Liquid Crystals
Zhu Yeqing, Hu Wei, and Cao Longgui
The evolution of (1+1)-D breathers in nonlocal nonlinear media is theoretically discussed, and it is modeled by the nonlocal nonlinear Schrdinger equation (NNLSE) which is got from the normalized equations and corresponding Fourier transform. In the balance, the potenfial is approximate to the 2nd order, a fundamentalThe evolution of (1+1)-D breathers in nonlocal nonlinear media is theoretically discussed, and it is modeled by the nonlocal nonlinear Schrdinger equation (NNLSE) which is got from the normalized equations and corresponding Fourier transform. In the balance, the potenfial is approximate to the 2nd order, a fundamental breathers solution is presented, and the solutions of the period and the maximal (minimal) beam width is obtained too. Without approximation, precise solutions of the period and the maximal (minimal) beam widths are also calculated here. Compared with the numerical simulations, it is obviously found that the analytical solutions are suitable in the strongly nonlocal case and the breathers solution in the 2nd approximation is always less accurate than that with no apptoximation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3000 (2010)
Effect of Temporal and Spatial Modulation on Noncollinear Autocorrelation
Sun Zhihong, Xia Yanwen, Liu Hua, and Fu Xuejun
The slip step Fourier transform method is adopted to study the coupled-wave equation of noncollinear autocorrelator. The influence of spatial intensity distribution and pulse chirp of the fundamental beams on measurement of pulse duration of second-order autocorrelation signal are simulated. Two fundamental beams and oThe slip step Fourier transform method is adopted to study the coupled-wave equation of noncollinear autocorrelator. The influence of spatial intensity distribution and pulse chirp of the fundamental beams on measurement of pulse duration of second-order autocorrelation signal are simulated. Two fundamental beams and only one fundamental beam modulated by spatial intensity distribution are respectively discussed. It is shown that the irregular spatial intensity distribution modulation of the second harmonic beams increases with the fundamental beam modulation and decreases with modulated intensity increase of the fundamental beam. The outside envelope of the autocorrelation with irregular spatial intensity distribution is the same as that of the autocorrelation without modulation. The pulse chirp only leads to efficiency decrease of autocorrelation. The method of pulse duration derived from outside envelope of autocorrelation is presented. The analyzing results are of reference value for the exact measurement of pulse duration..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3005 (2010)
Light-Controlled Spatial Solitons in Homeotropically Aligned Nematic Liquid Crystals
Pu Shaozhi, Zhan Kaiyun, and Hou Chunfeng
The propagation of spatial solitons in homeotropically aligned nematic liquid crystal is discussed by using the split-step Fourier algorithm. Applying one plane wave to generate pretilt angle in homeotropically aligned nematic liquid crystals′ and another incident beam is injected into the liquid crystal cell through tThe propagation of spatial solitons in homeotropically aligned nematic liquid crystal is discussed by using the split-step Fourier algorithm. Applying one plane wave to generate pretilt angle in homeotropically aligned nematic liquid crystals′ and another incident beam is injected into the liquid crystal cell through the cell′s centre. Then the evolution equation of the incident beam is given. When the incident beam enters 70 μm thick liquid crystal cell, the refractive index and orientation angle of the liquid crystal in the cell are numerically calculated. At last, the incident beam propagation in 70 μm and 100 μm thick homeotropically aligned nematic liquid crystal is obtained numerically. According to the theoretical analysis, it shows that the pretilt angle in the liquid crystal can be generated by one parallel beam instead of electric field. It is also found that in the 70 μm thick liquid crystal cell, the soliton is difficult to be found. However, in 100 μm thick liquid crystal cell, it is easy not only to get the soliton but also to get the breather whose vibration cycle changes with the intensity of incident beam..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3010 (2010)
Optical Design and Fabrication
Design of Multi-Layer Diffractive Optical Element with Bandwidth Integral Average Diffraction Efficiency
Xue Changxi, Cui Qingfeng, Pan Chunyan, and Tong Jingbo
The relation between bandwidth integrated average diffraction efficiency (BIADE) of multi-layer diffractive optical elements (MLDOE) and corresponding phase retardation expression is discussed, and the maximum BIADE and the corresponding design wavelengths are determined when the optical materials are selected, then thThe relation between bandwidth integrated average diffraction efficiency (BIADE) of multi-layer diffractive optical elements (MLDOE) and corresponding phase retardation expression is discussed, and the maximum BIADE and the corresponding design wavelengths are determined when the optical materials are selected, then the design of the BIADE of the MLDOE is realized exactly and maximumly. Based on the principle, to design a MLDOE with (PMMA) and polycarbonate as materials respectively, the maximum BIADE is 99.3% in visible waveband (0.4～0.7 μm), the corresponding design wavelengths are 0.435 μm and 0.598 μm, the heights of harmonic diffractive element (HDE) are 16.460 μm and 12.813 μm respectively, and the BIADE of the MLDOE designed with this method is 3.9% higher than that with the former method in which design wavelengths are 0.4 μm and 0.7 μm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3016 (2010)
Optical Design of Imaging Spectrometer Based on Acousto-Optic Tunable Filter
Chang Lingying, Zhao Baochang, Qiu Yuehong, Wen Desheng, and Ma Xiaolong
In order to acquire space, spectrum, and polarization information, the optical system which is applied to acousto-optic tunable filter(AOTF) imaging spectrometer is designed. The work principle of AOTF is described, then on the basis of instrument and system considerations, the optical parameters of the telescope and cIn order to acquire space, spectrum, and polarization information, the optical system which is applied to acousto-optic tunable filter(AOTF) imaging spectrometer is designed. The work principle of AOTF is described, then on the basis of instrument and system considerations, the optical parameters of the telescope and collimating optics are distributed reasonably. The optical design software CODE-V is used for the design, optimization and analysis of the optical system, and a refractive grating halfway along the crystal is used to simulate the effects of the AOTF. The +1 and -1 orthogonally polarized orders are produced by the AOTF at the same time. The whole system is achromatized from 400～900 nm using only three types of glass and imaging resolution excelled 32 lp/mm when the modulation transfer function (MTF) reaches 0.75..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3021 (2010)
Optical System Design of Space Sensor with Two Long Focal Length Lens
He Yinghong, Ma Zhen, Zhao Baochang, Chang Lingying, Chen Liwu, Ma Xiaolong, and Yi Hongwei
A compact space optical system without moving parts which can get two focal lengths is designed. Ritchey-Chrétien (R-C) mirror is common for long-focus system and short-focus system. A splitter prism is used for splitting the light into two beams relayed by transmitting optical system. The focal length is 4700 mm A compact space optical system without moving parts which can get two focal lengths is designed. Ritchey-Chrétien (R-C) mirror is common for long-focus system and short-focus system. A splitter prism is used for splitting the light into two beams relayed by transmitting optical system. The focal length is 4700 mm and F number is 13.4 for the long-focus system, and the focal length is 2350 mm and F number is 6.7 for the short-focus system. Some measure is taken to make sure the less degradation of MTF for thermal distortion, such as a kind of material with small thermal expansion using comrection between the primer mirror and the second mirror and material with good thermal property as mirror substrate for reduce surface distortion. The modulation transfer function (MTF) of optical system in condition of (19±3) ℃ is analyzed, which shows a good result for user′s requirement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3027 (2010)
Design of Reflective Zoom Systems with 3 Mirrors
Zhang Tingcheng, Wang Yongtian, Chang Jun, and M. M. Talha
A method based on the 3rd-order aberration theory is described for the design of mechanically compensated reflective zoom systems with 3 mirrors. By constrained optimization of a set of Seidel aberration coefficient functions, the initial construction parameters of the optical system can be achieved, and the design resA method based on the 3rd-order aberration theory is described for the design of mechanically compensated reflective zoom systems with 3 mirrors. By constrained optimization of a set of Seidel aberration coefficient functions, the initial construction parameters of the optical system can be achieved, and the design results prove the feasibility of this method. The limitation of the above method and the necessity of the design of reflective systems without obscuration are also pointed out. A new design theory is explored which could eliminate obscuration and correct aberrations at the same time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3034 (2010)
Optical Devices
Investigation of Uniform Illumination of Near-Field Targets Using a Conic Light-Emitting Diode Array
Huang Qilu, and Wu Fengtie
Based on geometrical optics and irradiance theory, a conic light-emitting diode array with uniform near-field lighting was analyzed. Formulas for calculating total irradiance from source to collecting screen was deduced. According to Sparrow′s criterion, the expression was calculated by using Matlab optimization toolboBased on geometrical optics and irradiance theory, a conic light-emitting diode array with uniform near-field lighting was analyzed. Formulas for calculating total irradiance from source to collecting screen was deduced. According to Sparrow′s criterion, the expression was calculated by using Matlab optimization toolbox. Furthermore, the software TracePro was used to simulate the designed array. The ray-tracing simulations showed that an array of light-emitting diodes assembled upon a conic surface can produce a wider angle distribution of light field than a flat array. The analysis and simulation of two-dimensional and three-dimensional of conic are carried out, and the uniformity of the illumination of the target is optimize. This method provided valuable reference to the LED lighting modules design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3039 (2010)
Reliability Assessment of Superluminescent Diodes from Performance Degradation Data
Chao Daihong, Ma Jing, and Zhang Chunxi
As the most important and fragile part of fiber optic gyroscopes (FOG), the reliabiliey of superluminescent diodes (SLD) determines the operational reliability and maintenance expenses of FOGs. Reliability of SLDs is studied based on degradation data for their long life characteristics. Based on analysis of degradationAs the most important and fragile part of fiber optic gyroscopes (FOG), the reliabiliey of superluminescent diodes (SLD) determines the operational reliability and maintenance expenses of FOGs. Reliability of SLDs is studied based on degradation data for their long life characteristics. Based on analysis of degradation mechanisms of SLDs under environmental stress firstly, normal-poisson hybrid stochastic process model is presented as their life distribution model whose parameters can be estimated from the degradation measures of the SLDs. The proposed method can obtain SLDs′ reliability without failure data, therefore overcomes the drawbacks of traditional time-to-failure analysis method which requires failure data. This estimation method shows its significance in test costs and time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3044 (2010)
Optics at Surfaces
Effect of Probe on Surface Plasmon Resonance
Hong Xiaogang, Xu Wendong, Zhao Chengqiang, and Tang Xiaodong
In order to get the best lithography conditions, the effect of the probe on surface plasmon resonance (SPR), which is utilized in probe induced surface plasmon resonance coupling nanolithography (PSPRN), has been investigated by using finite difference time domain (FDTD) method. The results show that SPR field enhancemIn order to get the best lithography conditions, the effect of the probe on surface plasmon resonance (SPR), which is utilized in probe induced surface plasmon resonance coupling nanolithography (PSPRN), has been investigated by using finite difference time domain (FDTD) method. The results show that SPR field enhancement effect is small with a small waist radius of fundamental mode Gaussian beam. When working in contact mode, Si probe with a tip radius of curvature of 10 nm, and 35 nm and 100 nm for Au prodes, make the SPR resonance angle change 0, 0.8°, 1°respectively. For Au prodes, smaller tip radius of curvature can get stronger local field enhancement effect. Analysis showed that with a Si probe of 10 nm tip radius of curvature or a Au probe of 35 nm tip radius of curvature probe, by adjusting the incident angle, it is likely to realize experimentally a 50 nm recording spot with a suitable SPR film structure..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3049 (2010)
Physical Optics
Theoretical Analysis of Influence of Laser Signal Strength on Range Precision in Single Photon Ranging
Wang Fei, Zhao Yuan, Zhang Yu, and Sun Xiudong
The range precision of single photon pulsed ranging system is influenced by the random arrival of echo photon. Based on the statistical property of echo photon and photoelectron, the influence of the echo signal strength and pulse width on the range precision is discussed. For normal rectangular echo signal, the relatiThe range precision of single photon pulsed ranging system is influenced by the random arrival of echo photon. Based on the statistical property of echo photon and photoelectron, the influence of the echo signal strength and pulse width on the range precision is discussed. For normal rectangular echo signal, the relation between the range precision and signal strength and pulse width is obtained. Results show that higher signal strength and narrower pulse width produce better range precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2771 (2010)
Lock-In Infrared Thermography for the Non-Destructive Testing of Fatigue Specimen with Defects
Zhao Yanguang, Guo Xinlin, and Ren Mingfa
Lock-in infrared thermography method is gradually used in fatigue studies because of its advantages such as real-time, quick-reaction, non-destructive, non-contact and so on. Non-destructive testing is applied to fatigue specimen with defects, and the fatigue limit is detected rapidly based on lock-in infrared thermogrLock-in infrared thermography method is gradually used in fatigue studies because of its advantages such as real-time, quick-reaction, non-destructive, non-contact and so on. Non-destructive testing is applied to fatigue specimen with defects, and the fatigue limit is detected rapidly based on lock-in infrared thermography. In parallel, the results are analyzed using lock-in infrared thermography system developed by Cedip in French. It shows that more information of internal detects can be found from phase image than from amplitude image. The experimental procedure indicates that a proper testing frequency is the key to the non-destructive testing. The datas reveale that larger area of defect leads to a precise testing result and the fatigue limit of the specimen decreases with the increase of the defect depth..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2776 (2010)
Study on Characteristics and Structures of Amorphous Silicon Nitride Thin Films Applied in Micro-Bolometer
Zhou Dong, Xu Xiangdong, Wang Zhi, Wang Xiaomei, and Jiang Yadong
Silicon nitride films are widely used in micro-bolometer focal plane arrays as supporting layer and insulation layer. In this paper, silicon-rich hydrogenated amorphous silicon nitrides (α-SiNxH，0.80≤x≤1.16) were prepared by radio-frequency plasma-enhanced vapor deposition. The film microstructures were analyzed using Silicon nitride films are widely used in micro-bolometer focal plane arrays as supporting layer and insulation layer. In this paper, silicon-rich hydrogenated amorphous silicon nitrides (α-SiNxH，0.80≤x≤1.16) were prepared by radio-frequency plasma-enhanced vapor deposition. The film microstructures were analyzed using X-ray photoelectron spectroscopy (XPS) and Fourier transimission infrared spectroscopy (FTIR). Results reveal that α-SiNxH contain the basic structural units of Si3N4. Moreover, the Si-N stretching modes located at 790, 820 and 950 cm-1, are ascribed to Si3-Si-N, N2-Si-H2, and H-Si-N3 configurations, respectively. The residual stresses were measured by curvature measurement, indicating that the residual stress in the film generally exhibits tension, but this tensile stress gradually decreases while the SiH4 flow rate increases. The theoretical analysis shows that the H-Si-N3 configuration is helpful for developing tensile stress, while the Si3-Si-N and Si-Si configurations are helpful for compressive stress. Therefore, by optimizing the processing conditions, α-SiNxH, with suitable microstructures can be prepared, by which the film stress can be better controlled..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2782 (2010)
Infrared Image Enhancement Method Based on Stationary Wavelet Transformation and Retinex
Zhan Bichao, Wu Yiquan, and Ji Shouxin
As infrared image enhancement method based on wavelet transformation has the problem of unperfect visual effect, and Retinex enhancement algorithm can enhance visual effect of the image by improving brightness uniformity, a method based on stationary wavelet transformation and Retinex is proposed. Firstly, the infraredAs infrared image enhancement method based on wavelet transformation has the problem of unperfect visual effect, and Retinex enhancement algorithm can enhance visual effect of the image by improving brightness uniformity, a method based on stationary wavelet transformation and Retinex is proposed. Firstly, the infrared image is decomposed into high-frequency detail and low-frequency approximation components at various resolutions, and the low frequency subband image of the largest scale is enhanced by multiscale Retinex algorithm. Then, the high-frequency subband images are denoised by Bayesian shrinkage method, and the gain coefficients of high-frequency subbands are available by calculating the local contrast of the enhanced low-frequency subband based on fuzzy rules to get the enhanced high-frequency subband images. Finally, the enhanced image is reconstructed by the low-frequency subband and high-frequency subbands. Experiments with qualitative and quantitative evaluation are carried out for many images, and the proposed method is compared with histogram double equalization method, second generation wavelet transform method, curvelet transform method, and multiscale Retinex method. Experimental results show that the proposed method can enhance image details and suppress noise better, and the whole visual effect is improved significantly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2788 (2010)
Infrared Optical Properties of Thermochromic Energy-saving Thin Films with Nanostructure
Zhu Huiqun, Li Yi, Wang Haifang, Yu Xiaojing, Zhou Sheng, Huang Yize, Zhang Hu, Zhang Wei, Sun Ruoxi, and Zhang Yuming
The low cost nanostructure thermochromic energy-saving thin films are fabricated by magnetron sputtering deposition at room temperature and oxidation in air atomsphere. The film properties are studied through SEM, XRD, Raman spectroscopy and infrared spectrum analyzer. The relation between the oxidation annealing and mThe low cost nanostructure thermochromic energy-saving thin films are fabricated by magnetron sputtering deposition at room temperature and oxidation in air atomsphere. The film properties are studied through SEM, XRD, Raman spectroscopy and infrared spectrum analyzer. The relation between the oxidation annealing and microstructure and infrared switching characteristics of VO2 thin films with temperature are analyzed. The major factors which affect the film properties such as the grain size, crystal lattice structure, composition, thermal hysteresis and infrared transmittance and their control methods are obtained. The optimal processing parameters are used to fabricate VO2 nanostructure thermochromic energy-saving thin films on glass with high energy efficiency. The average grain size of VO2 nanocrystals is about 45 nm, calculated by the correlation equation based on XRD and Raman spectrometer. The measured results shows that the infrared light transmittance at 2.5 μm is more than 50%, the phase transition temperature is 39 ℃, visible light transmittance is about 53%, and the VO2 nanostructure energy-saving thin film have good thermochromic properties..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2794 (2010)
Visual Attention-Driven Geodesic Active Contour Model and Its Application
Liu Bin, and Hu Chunhai
In order to detect multi-motion targets in time sequenced forward looking infared (FLIR) images, a novel automatic detection method is proposed. First, the speed of 3D spatiotemporal texture vectors is used to measure motion features. Then, the saliency of motion target is defined under the frame of visual attention. SIn order to detect multi-motion targets in time sequenced forward looking infared (FLIR) images, a novel automatic detection method is proposed. First, the speed of 3D spatiotemporal texture vectors is used to measure motion features. Then, the saliency of motion target is defined under the frame of visual attention. So salient moving objects are detected and extracted by accumulating directionally-consistent optical flow. The regions are regarded as final visual attention regions. An improved geodesic active contour model is built, where the topology-free deformable evolving curve is attracted by the boundaries of attention regions. A gradient based convergence term forces the curves evolution to stop on the object boundaries. The validity of the proposed method is proved experimentally and the results of multi-dataset are given. Compared to other traditional methods, the proposed method has a good noise tolerance and can handle fast or slow image variations. It has no response to unnecessary motion and only focuses on the salient motion targets. The multiple targets boundaries are located due to implementation of level set scheme, which gives a reliable input for targets identifying and tracking or 3D reconstruction and representation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2800 (2010)
Detection of Small Target in Infrared Image Based on Background Predication by FLS-SVM
Wu Yiquan, and Yin Danyan
A detection method of small target in infrared image is proposed, which is based on the background predication by fuzzy least squares support vector machine (FLS-SVM) and threshold segmentation by fuzzy Tsallis-Havrda-Charvat entropy. Firstly, the fitting function is obtained from the training samples by using FLS-SVM A detection method of small target in infrared image is proposed, which is based on the background predication by fuzzy least squares support vector machine (FLS-SVM) and threshold segmentation by fuzzy Tsallis-Havrda-Charvat entropy. Firstly, the fitting function is obtained from the training samples by using FLS-SVM and the background in infrared image is predicted. Then, the predicted image subtracted from the source image gives the residual-error image. The residual-error image is segmented by the proposed threshold selection method based on fuzzy Tsallis-Havrda-Charvat entropy so as to separate small target and noise from the residual background. Finally, the true small target is further detected based on the stability of the target gray and the consistency of target trajectory. The experimental results are given and analyzed. They are compared with the detection results of the background predication methods based on LS-SVM or least squares. The results show that the proposed method has higher detection probability and the gain of signal-to-noise ratio (GSNR) and it is superior to the above-mentioned methods..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2806 (2010)
Multiscale Truncation for Dim and Small Target Background Suppression
Zhou Huixin, Qin Hanlin, Lai Rui, and Liu Shangqian
Complex background suppression of infrared dim and small target detection is a key problem for finding long-distance target in infrared warning system. A complex background suppression algorithm based on multiscale truncation, which combines the singular value decomposition with the dual tree complex wavelet transform Complex background suppression of infrared dim and small target detection is a key problem for finding long-distance target in infrared warning system. A complex background suppression algorithm based on multiscale truncation, which combines the singular value decomposition with the dual tree complex wavelet transform (DTCWT), is presented. Firstly, DTCWT is adopted to decompose the input infrared image, which extracts multi-scale detail features of images. Then, according to difference between targets and background clutter signals, the singular value decomposition is introduced to process sub-bands, and maximum eigenvalues are utilized to compose the sub-bands. Finally, the image is synthesized by the modified sub-bands, then targets and background details are separated, by which background suppression is realized. Experimental results validate that the presented method could suppress the structured background in some degree, and preserve and enhance the target signal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2812 (2010)
CMOS Compatible Self-Aligned Micromachined Thermopile IR Detector
Xu Dehui, Xiong Bin, and Wang Yuelin
Due to its advantages of uncooling, ease of operation and low cost, micromachined thermopile infrared (IR) detectors have a broad application. A novel complementary metal-oxide-semiconductor (CMOS) compatible self-aligned micromachined thermopile IR detector is proposed to reduce the fabrication complication and fabricDue to its advantages of uncooling, ease of operation and low cost, micromachined thermopile infrared (IR) detectors have a broad application. A novel complementary metal-oxide-semiconductor (CMOS) compatible self-aligned micromachined thermopile IR detector is proposed to reduce the fabrication complication and fabrication difficulty of micro etching windows. Compared with conventional micromachined thermopile IR detectors, the etching windows in the self-aligned thermopile structure are determined by space between polysilicon thermocouple legs rather than by photolithographic processing. Two types of thermopile structures are designed and fabricated in order to study the influence of device structure on IR detector performance. Experimental results show that the rectangular thermopile structure has a higher output voltage and responsivity, whereas the circular IR detector exhibits a smaller response time and a higher specific detectivity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 2817 (2010)
Quantum Optics
Nonclassical Properties of Fields in Pair Coherent States Interacting With Two Two-Level Atoms
Zheng Xiaolan, and Chen Zihong
Under the Jaynes-Cummings model, the evolution of nonclassical properties of two cavity modes is discussed, such as squeezing, sub-Poissonian statistics and violations of Cauchy-Schwarz inequalities and Bell inequalities are discussed. The two cavity modes are initially in pair coherent states, each mode interacts withUnder the Jaynes-Cummings model, the evolution of nonclassical properties of two cavity modes is discussed, such as squeezing, sub-Poissonian statistics and violations of Cauchy-Schwarz inequalities and Bell inequalities are discussed. The two cavity modes are initially in pair coherent states, each mode interacts with two two-level atoms resonantly. Numerical simulation results show that some nonclassical properties can be enhanced after resonant interaction between the atoms and the cavity and the performance of a selective atomic measurement. Moreover, after atom-cavity interaction, a resonant classical microwave field is applied to the atoms, which performs a unitary transformation on the atomic states, a selective measurement is performed to the atoms after selecting transform parameters the two-mode squeezing can be somehow enhanced..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3054 (2010)
Scattering
Diffusion Properties of Brownian Particles in Dense Suspensions by Low-Coherence Dynamic Light Scattering
Xia Hui, Li Fushi, Chen Zhiquan, Lin Xu, Xiao Yuanyuan, Huang Hao, and Li Qinglin
A method of low-coherence dynamic light scattering is used to study the diffusion properties of Brownian motion particles in concentrated colloidal suspensions. Based on the single scattering theory, considering the variation of refractive index of suspensions with the volume fraction, the effective diffusion coefficieA method of low-coherence dynamic light scattering is used to study the diffusion properties of Brownian motion particles in concentrated colloidal suspensions. Based on the single scattering theory, considering the variation of refractive index of suspensions with the volume fraction, the effective diffusion coefficients are obtained by analyzing the single scattering spectra that are measured by using low-coherence dynamic light scattering method. The effective coefficients for three different particles are investigated as a function of volume fractions. As a result, the diffusion properties of Brownian particles are influenced by hydrodynamic interactions and statistical structure factor of particles. The diffusion coefficient decreases with increase of the volume fraction. In the volume fraction range from 0.01 to 0.2, the measured effective diffusion coefficients are in good agreement with the theoretical values by considering the Percus-Yevick and Cohen-de Schepper approximations. It is confirmed that the low-coherence dynamic light scattering technique can be used to measure the diffusion properties of Brownian particles with different volume fractions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3059 (2010)
Thin Films
Design and Error Analysis of Infrared Dual-Channel Band Pass Filter with Wide Rejection Band for Detection Application
Chen Youhua, and Wang Zhibing
In order to meet the requirements of high transmittance in pass bands, high reflectance in rejection bands, small ripple coefficient for detecting 1, 2-propanediol dinitrate with infrared detector cell, an infrared dual-channel band pass filter with proper rejection band has been designed using the combined method of tIn order to meet the requirements of high transmittance in pass bands, high reflectance in rejection bands, small ripple coefficient for detecting 1, 2-propanediol dinitrate with infrared detector cell, an infrared dual-channel band pass filter with proper rejection band has been designed using the combined method of the Herpin refractive index principle and local optimization, as well as choosing PbTe/ZnSe as the material of high/low refractive index. A dual channel filter with pass bands of 5.9～6.2 μm and 11.9～12.2 μm and the average transmittance exceeds 90% and 65% respectively was designed. An error analysis of layer physical thickness and refractive index has been done for the design, which shows that the precision of deposition rate should be controlled within 3.5%, meanwhile, the refractive index accuracy should be lower than 3%, the refractive index has greater effect on the reflectance than the thickness, and the double half-wave film is more sensitive in the changes of refractive index and the thickness..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 30, Issue 10, 3064 (2010)
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