Contents
2015
Volume: 35 Issue 2
52 Article(s)
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Atmospheric Optics and Oceanic Optics
Cyclic Spectral Density Analysis of Free Space Optical Sub-Carrier Signals
Xie Mengqi, and Ke Xizheng
The background of atmosphere turbulence on free space optical sub-carrier modulation is set. The expressions of the cyclic auto- correlation function and the cyclic spectral density of quadrature phase shift keying (QPSK) signals are derived and the cyclic auto- correlation function and the cyclic spectrum density of sThe background of atmosphere turbulence on free space optical sub-carrier modulation is set. The expressions of the cyclic auto- correlation function and the cyclic spectral density of quadrature phase shift keying (QPSK) signals are derived and the cyclic auto- correlation function and the cyclic spectrum density of series of experimental QPSK data are analysed. The results show that both additive and multiplicative noises in the experimental data are influenced by the atmosphere turbulence. And the turbulence which is not very strong can not disturb cyclostationarity of QPSK signals. The main factor of received signal to noise ratio is the power difference between the signal and low frequency noise. By adding a time window which can restrain low frequency noise, the signal to noise ratio of free space optical subcarrier modulation system can be improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 201001 (2015)
Measurement of PM 2.5 Concentration Based on the Charge-Coupled Device Backward Scattering Lidar
Hu Miao, Xie Jialiang, Wu Duanfa, Zeng Rong, Li Qiliang, Zhou Xuefang, Qian Zhengfeng, Wei Yizhen, Xiang Zhen, and Cai Ju
A theoretical measurement model of atmospheric particulate concentration is built, considering Mie scattering theory and laser propagation equation. An experimental device is designed to monitor the real-time PM 2.5 concentration is introduced by using a charge- coupled device (CCD) backward scattering lidar. The experA theoretical measurement model of atmospheric particulate concentration is built, considering Mie scattering theory and laser propagation equation. An experimental device is designed to monitor the real-time PM 2.5 concentration is introduced by using a charge- coupled device (CCD) backward scattering lidar. The experimental system consists of a 532 nm wavelength laser as the light source and a CCD as detector of back scattering light. According to the real time image captured by the CCD, the gray level value matrix is extracted, while the intensity distribution of the scattering image is analyzed. Compared with the results of a PM 2.5 monitor for Thermo Fisher Scientific Company, five formulas about PM 2.5 concentration and scattering lighting are concluded with a fitting degree better than 0.95. A further popularization of this atmospheric particulate concentration monitoring device which is low in cost and convenient in use, will play a significant role in investigating the movement of PM 2.5 and depicting pollutant distribution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 201002 (2015)
Detectors
Investigation on the Mechanism and Positioning Error of Multi-Star Spots Extraction of Iteratively Weighted Center of Gravity algorithm
Zhang Jun, Hao Yuncai, and Liu Da
Improving the positioning accuracy of star spots is still one of crucial technologies in high precision star trackers. The minimum meansquared error of the conventional center of gravity (COG) and Gaussian curve fitting (GCF) algorithm for positioning is about 0.1 pixel, hardly to meet the future demand for highprecisiImproving the positioning accuracy of star spots is still one of crucial technologies in high precision star trackers. The minimum meansquared error of the conventional center of gravity (COG) and Gaussian curve fitting (GCF) algorithm for positioning is about 0.1 pixel, hardly to meet the future demand for highprecision positioning. In the field of adaptive optics, an iteratively weighted center of gravity (IWCOG) is proposed for wave- front localization of Shack- Hartmann sensor with superior performance to the first two algorithms in locating accuracy. However, the positioning mechanism of IWCOG and the performance on the multi-star positioning accuracy are currently unknown. On the one hand, this paper introduces the positioning mechanism of the algorithm from a theoretical perspective of Meanshift and proves the convergence of the IWCOG algorithm. On the other hand, 10000 randomly star spots are generated with Monte Carlo method in every single simulation to study the influence of IWCOG algorithm on multi- star positioning accuracy in star tracker by studying relationship between the star point parameters, signal to noise ratio and positioning errors. The result shows that there are 44% samples with positioning error lower than 0.02 pixel and 72% with error lower than 0.04 pixel using IWCOG algorithm under signal to noise ratio R equal to 40, much better than the COG with only 0.8% and 1.9% , basically meeting the positioning requirements of super- high accuracy star tracker..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 204001 (2015)
Integration Time Optimization for TDI CMOS Image Senor
He Chunliang, Li Binqiao, Liu Zhenwang, and Xu Jiangtao
In order to improve the image quality of the time delay integration complementary metal oxide semiconductor (TDI CMOS) image sensor, the influence of integration time selected on image quality is studied. Based on the rolling shutter readout principle, the impacts of integration time on signal to noise ratio (SNR) and In order to improve the image quality of the time delay integration complementary metal oxide semiconductor (TDI CMOS) image sensor, the influence of integration time selected on image quality is studied. Based on the rolling shutter readout principle, the impacts of integration time on signal to noise ratio (SNR) and modulation transfer function (MTF) are analyzed respectively. According to the results of the analysis, it is proposed that in the case of series selected，the optimal value exists in the selection of integration time, which makes a better image quality. To validate the conclusion, on the basis of self-developed TDI CMOS image sensor chip and field programmable gate array (FPGA) development board, the imaging testing system of TDI CMOS image sensor is set up. By using MTF × SNR as the image quality evaluating index in the experiment, the experimental results show that under the selected camera parameters, the stage is 8, and the light intensity is 20 lx, when the integration time is 64 ms, the best image quality can be obtained and the MTF× SNR is maximum..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 204002 (2015)
Fiber Optics and Optical Communications
Mode Field Measurement and Discharge-Redress Techniques for Polarization-Maintaining Photonic Crystal Fibers
Li Hongying, Yang Yuanhong, and Yang Wei
The model for characterizing the mode field of polarization-maintaining photonic crystal fiber (PMPCF) is proposed. The on-line mode field testing setup for PM-PCF is established based on the near field spot imaging method and the absolute measurement of mode field parameters is achieved with an infrared camera system.The model for characterizing the mode field of polarization-maintaining photonic crystal fiber (PMPCF) is proposed. The on-line mode field testing setup for PM-PCF is established based on the near field spot imaging method and the absolute measurement of mode field parameters is achieved with an infrared camera system. The effect of discharge on the PM- PCF mode field redress is investigated and the evolutions of mode field parameters are also obtained by numerical simulations. The calculation model of the splicing loss between PM- PCF and conventional polarization maintaining fiber is derived, and the low loss splicing condition is also determined and experimentally verified. The result demonstrates that the loss splicing between PM-PCF and conventional polarization maintaining fibers is successfully realized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 206001 (2015)
Photonic Crystal Fiber Sensor Based on Surface Plasmonic and Directional Resonance Coupling
Shi Weihua, and Wu Jing
A novel photonic crystal fiber refractive index sensor with a large dynamic detection range is proposed. Two air holes are used as analyte channels. One coated with gold layer is used as surface plasmon resonance to measure the liquid index below that of the quartz substrate and the other filled with the test liquid isA novel photonic crystal fiber refractive index sensor with a large dynamic detection range is proposed. Two air holes are used as analyte channels. One coated with gold layer is used as surface plasmon resonance to measure the liquid index below that of the quartz substrate and the other filled with the test liquid is used as the directional resonance coupling to measure the index that of above the quartz substrate. A broad index range of analyte from 1.33 to 1.52 with high sensitivity can be achieved. The properties of the index sensor are analyzed by finite element method (FEM) with the boundary condition of anisotropic perfectly matched layer (PML). The results show that the maximal sensitivities reach 13500 nm/RIU and 28700 nm/RIU when refractive index is in the range of 1.32 to 1.44 and 1.46 to 1.52 respectively, where RIU is refractive index unit..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 206002 (2015)
Improved Designs of All-Fiber 3×3 Interleaver with Flat-Topped Passband
Lu Huaiwei, Lu Yan, Pu Huilan, and Luo Guanwei
In order to improve the transmission performance of the all-fiber 3×3 interleaver, the output expression is derived and simulation is performed. Through the analysis and optimization, the optimal structure parameters is put forword. The calculating and experimental results indicate that the crosstalk characteristiIn order to improve the transmission performance of the all-fiber 3×3 interleaver, the output expression is derived and simulation is performed. Through the analysis and optimization, the optimal structure parameters is put forword. The calculating and experimental results indicate that the crosstalk characteristics, the channel isolation, stopband rejection, passband flat-topped degrees and the rolloff in transition band can be improved greatly, and the reduced sidelobe level of channel of the proposed device is more than 16 dB in comparison with that of the convention all-fiber 3×3 interleaver. A 100 GHz three-port interleaver with a flat-topped passband bandwidth is demonstrated by experiment. The experimental and theoretical results coincide with each other..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 206003 (2015)
Fourier Optics and Signal Processing
Application of EMD Threshold Filtering for Fiber Optical Gyro Drift Signal De-Noising
Cui Bingbo, Chen Xiyuan, and Song Rui
The drift signal of fiber optic gyroscope (FOG) is often buried in noise. It is difficult to compensate drift directly, and a novel threshold filtering method based on empirical mode decomposition (EMD) (designated as EMD-T) is proposed as a pre-processing tool. Based on the noise spread model of EMD, a bounded noise aThe drift signal of fiber optic gyroscope (FOG) is often buried in noise. It is difficult to compensate drift directly, and a novel threshold filtering method based on empirical mode decomposition (EMD) (designated as EMD-T) is proposed as a pre-processing tool. Based on the noise spread model of EMD, a bounded noise assist analysis method is introduced to improve the decomposition accuracy of EMD. The noises with low magnitude and high frequency are compressed into early intrinsic mode functions. The static output of interferometric FOG is adopted to verify the effectiveness of EMD-T. Comparison analysis with filtering methods based on wavelet packet transform (WPT) and conventional EMD (CEMD) is done. Experimental and Allan variance analysis results show that EMD-T outperforms denoising method based on WPT and CEMD. The quantization noise (Q) and angle random walk (N) are decreased from 0.7862 μrad and 4.58×10-3（°）·h-1/2 to 0.1340 μrad and 9.03×10-4（°）·h-1/2, respectively, after applying EMD-T..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 207001 (2015)
Geometric Optics
Study of the Optical Systems with Illuminance and Luminance Uniformity Simultaneously for LED Lighting
Qian Keyuan, and Hu Xiaojia
For road lighting, the human eyes observe surface luminance rather than the illuminance. An ideal road lighting system should be able to achieve both the uniformity of illumination and luminance. A design method is presented to realize the illumination and luminance uniformity of road surface. According to the CommissiFor road lighting, the human eyes observe surface luminance rather than the illuminance. An ideal road lighting system should be able to achieve both the uniformity of illumination and luminance. A design method is presented to realize the illumination and luminance uniformity of road surface. According to the Commission Internationale Ed I′eclairage (CIE) standard simplified luminance coefficient table, the luminance coefficient of all road surface points can be obtained. Then these parameters are analyzed by using the least square method, so as to obtain the optimal illumination distribution. According to the minimum energy block iterative methodology, we mesh both the light source and the receiving surface. With the three- dimensional free- form surface design method, the optical lens are obtained which can get the illumination uniformity of 93.47% and the luminance uniformity of 86.94% and 89.26% for a C1 double lane road surface..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 208001 (2015)
Free-Form Reflector Design for Beam Shaping of Laser Diode
Tang Jian, and Yang Bo
Laser with straight- line light pattern and uniform illumination is required in many measurement systems and laser welding systems. Instead of the traditional methods using diffractive optical elements and cylindrical lens, a free- form surface design method for laser diode source is proposed to improve the utilizationLaser with straight- line light pattern and uniform illumination is required in many measurement systems and laser welding systems. Instead of the traditional methods using diffractive optical elements and cylindrical lens, a free- form surface design method for laser diode source is proposed to improve the utilization efficiency of the light energy and the optical lighting effect, utilizing a free- form reflector to distribute the light uniformly in one direction and collimate the light in the orthogonal direction. Through the establishment of free surface model, constructing the partial differential equation, and solving the point cloud of surface, the shape of the freeform surface is obtained. Compared with the traditional methods in the line pattern design, the efficiency and uniformity are both significantly enhanced by this method. The simulation result shows that an illuminance uniformity is about 90% and an efficiency about 99% (without considering the reflectance loss) are achieved within 150° of the spread angle..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 208002 (2015)
Materials Choose for Mid-Wave/Long-Wave Dual-Waveband Infrared Optics
Fu Qiang, and Zhang Xin
To apply the new generation infrared detector successfully, it is necessary to design dual-band/multi-band optical imaging systems. A calculation evaluation method to select materials for dual-band infrared optical imaging systems is proposed. The criterion includes the absolute lens power and the average defocus evaluTo apply the new generation infrared detector successfully, it is necessary to design dual-band/multi-band optical imaging systems. A calculation evaluation method to select materials for dual-band infrared optical imaging systems is proposed. The criterion includes the absolute lens power and the average defocus evaluated at a number of wavelengths in the designing radiation waveband. Evaluation of all potential combinations of materials by using this method, the optimal combination of materials and the initial focal power distribution for optical components can be obtained rapidly and efficiently. Through analysis and evaluation, ZnS/IG2 is the best two-lens material combination mode for mid-wave/long-wave dual-waveband infrared optics. Ge/ZnS/GASIR1 is the best three-lens material combination mode for mid-wave/long-wave dual-waveband infrared optics. As it is proved that the method is valued through designing and analyzing the combinations detailed. These best combinations can be used as lens elements to provide a good starting point for designing actual optical systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 208003 (2015)
Holography
A New Look-up Table Method of Holographic Algorithms Based on Compute Unified Device Architecture Parallel Computing
Jiang Xiaoyu, Cong Bin, Pei Chuang, Yan Xingpeng, and Zhao Kai
We propose a new look- up table algorithm, named trigonometric look- up tables (T- LUT) method to increase the speed of coherent ray trace (CRT）algorithm in generating holograms. The proposed algorithm is based on the original ray tracing method. By using a series of mathematical approximation changes and identical traWe propose a new look- up table algorithm, named trigonometric look- up tables (T- LUT) method to increase the speed of coherent ray trace (CRT）algorithm in generating holograms. The proposed algorithm is based on the original ray tracing method. By using a series of mathematical approximation changes and identical transformations, we generate a pure phase look- up table. This look- up table has three- dimensional features, fast generating speed, high precision, less memory capacity and so on. The new method overcomes CRT′ s shortcomings in computing the phase repeatedly. We implement T- LUT on graphics processing unit (GPU) using parallel computing by compute unified device architecture (CUDA), and optimize it three times. After algorithm optimizing, a series of experiments are carried out to verify the results by using a single GPU card. Our results indicate that the T- LUT algorithm can effectively shorten the computing time without sacrificing the quality of hologram reconstruction. Due to the different quantities of spatial samples, the speed has increased 30 to nearly a thousand times compared with original ray tracing algorithm implemented on GPU..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 209001 (2015)
Encrypted Holographic Watermarking Technology with Decrypted Image Superposed No Noise
Liu Zhen, Bai Taotao, and Lu Peng
A new encrypted computer-generated holographic technique is presented. The watermark image is encoded with double-random-phase encoding. The encrypted image with complex value is transformed to hologram by conjugate symmetric extension and Fourier transform. The decrypted image is not superimposed by perceptual noise. A new encrypted computer-generated holographic technique is presented. The watermark image is encoded with double-random-phase encoding. The encrypted image with complex value is transformed to hologram by conjugate symmetric extension and Fourier transform. The decrypted image is not superimposed by perceptual noise. The original watermark is quick response (QR) code. The hologram generated from the preprocessed QR code is embedded in the intermediate frequency coefficients of original image. The extracted QR code from the watermarked image under print-scan attack can be decoded correctly. The QR code represents not only a picture, but also text message. So the message decoded from the QR code makes authority verification more precisely. The proposed algorithm is of high practical value..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 209002 (2015)
Image Processing
Real-Time Point Feature Extraction Based on Connected Components Labeling and Distributed Computing
Yu Xiaoyu, Guo Yubo, Chen Gang, and Ye Dong
In the vision measurement for high speed moving target, the image sequence with high resolution and high frame rate brings a lot of datas. How to recognize the cooperation target quickly and extract the feature information in real-time is becoming a challenge in vision measurement system. In each clock cycle of high spIn the vision measurement for high speed moving target, the image sequence with high resolution and high frame rate brings a lot of datas. How to recognize the cooperation target quickly and extract the feature information in real-time is becoming a challenge in vision measurement system. In each clock cycle of high speed camera, multi- pixel is transmitted in parallel. In this situation, a hardware accelerating structure based on multi- dimensional pyramid is proposed, the task of global searching and connected components labeling is realized, the features of connected components are extracted real- timely based on the labeling results. In field programmable gate array, with the pyramid structure formed by two- dimensional processing element (PE) array and multi-label feature statistical structure formed by one-dimensional PE array, the high density computing process of data flow is distributed into each PE node equally. Combining with the parallel pipeline, the global searching and labeling process which takes a remarkable time- consuming in ordinary vision system is accomplished synchronously with image transmission. It is verified that the distributed computing structure for feature extraction can deal with real- time data processing at the flow rate of 680 Mpixel/s at the frequency of 85 MHz with CameraLink interface. As a preprocess part, it can be used in high-speed vision measurement system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 210001 (2015)
A Fast Lens Focus Measurement Method Based on Blurred Image Processing
Chen Rongjun, Tan Hongzhou, Tan Weiqing, Xiong Wenting, and Zhu Xiongyong
The precise measurement of the focal length is directly related to the normal use of optical instruments and give full play to its technical performance. A new practical method based on the model of optical out of focus imaging and blurred image processing of quickly and automatically measuring the focal length is propThe precise measurement of the focal length is directly related to the normal use of optical instruments and give full play to its technical performance. A new practical method based on the model of optical out of focus imaging and blurred image processing of quickly and automatically measuring the focal length is proposed. Based on the principle of optical imagery the mathematical model of focus measurement principle is proposed under the condition of blurred image. The proposed method adopts the least square method for fitting circles and calculates the distance between two diffuse light spots in blurred image. The lens focal length use the calculated distance is calculated. Experiments prove that the proposed method can estimate the distance between diffuse light spots with high accuracy so as to realize the measurement of automatic focus more accurately and quickly. The proposed approach takes only one blurred image, compared with traditional focus measurement method, the amount of calculation is reduced, the speed and reliability is improved, the complexity of system is reduced..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 210002 (2015)
Imaging Systems
Improving Image Quality by Using CCD Subpixel Imaging
Li Yapeng, and He Bin
In order to overcome the disadvantages in existing charge coupled device (CCD) subpixel imaging realization ways, such as complex structure, high subpixel precision and so on, a subpixel imaging method with single CCD camera by using high precision two- axis translation table to imaging the target at a certain distanceIn order to overcome the disadvantages in existing charge coupled device (CCD) subpixel imaging realization ways, such as complex structure, high subpixel precision and so on, a subpixel imaging method with single CCD camera by using high precision two- axis translation table to imaging the target at a certain distance is proposed and implemented. The multiple low- resolution images, which have half- pixel shift with each other attained by photographing target in fixed object distance using the proposed method, are interpolated and reconstructed based on cubic B spline interpolation and interlacing, and high resolution images are achieved. Then, point spread function is estimated by using knife edge method, and final high resolution image is got after performing image restoration to above reconstructed high resolution image. Results show that visual spatial resolution is improved to 1.4 times and image aliasing effect is reduced by using subpixel imaging and modulation transfer function area (MTFA) is increased to 0.2937 from 0.1577 by performing image restoration. Experiment demonstrates that subpixel imaging can enhance spatial resolution, reduce image aliasing and improve image quality. Image restoration can effectively compensate modulation transfer function (MTF) of reconstructed high resolution image, which solves the problem of spatial resolution enhancement but MTF reduction in subpixel imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 211001 (2015)
Low Contrast Target Polarization Recognition Technology Based on Lifting Wavelet
Zhang Su, Fu Qiang, Duan Jin, Zhan Juntong, and Jiang Huilin
To resolve the low recognition ratio problem of the target captured in the low contrast environment, a polarization information fusion method based on wavelet lifting algorithm is proposed. The target is detected by the use of polarization technology, and the wavelet lifting algorithm with the advantage of less computaTo resolve the low recognition ratio problem of the target captured in the low contrast environment, a polarization information fusion method based on wavelet lifting algorithm is proposed. The target is detected by the use of polarization technology, and the wavelet lifting algorithm with the advantage of less computation and higher processing speed is applied to decompose the polarization angle and degree of the polarization into high and low parts, then these two parts are fused with different rules to make the target edge contour distinguish from the low contrast background with full and clear details, which is more suitable for human eyes to recognize the target. A large number of target recognition experiments in low contrast environment and fusion results evaluation standards show that the proposed algorithm can effectively enhance the target recognition ratio, and its feasibility in low contrast environment is verified..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 211002 (2015)
High-Precision On-Orbit Assessment of MTF for Space CCD Camera
Li Jin, Xing Fei, and Wang Chong
Given that on-orbit modulation transfer function (MTF) for space charge coupled device (CCD) camera has the disadvantage of low assessing precision caused by noise in the process of image acquisition, a new high-precision assessment approach of MTF for space CCD camera is proposed. The accurate knife-edge direction is Given that on-orbit modulation transfer function (MTF) for space charge coupled device (CCD) camera has the disadvantage of low assessing precision caused by noise in the process of image acquisition, a new high-precision assessment approach of MTF for space CCD camera is proposed. The accurate knife-edge direction is extracted according to the image motion velocity model which is built based on the characteristics of CCD dynamic imaging. The theory model of MTF is corrected when noise is considered. And the line spread function (LSF) is computed based on the parameter transfer function model of CCD camera. The LSF performs the derivative operation and Fourier transform to obtain the MTF. Experimental analysis denotes that the proposed method can efficiently estimate on-orbit MTF. Compared with the traditional knife-edge method, the assessment value of MTF has improvement of 28.71% . The proposed approach can effectively solve the problem of lower precision on-orbit assessment of MTF..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 211003 (2015)
Principle and Simulation of a Spatially Modulated Full Stokes Parameters Polarization Imaging System
Hu Qiaoyun, Yang Weifeng, Hu Yadong, and Hong Jin
This paper introduces a new polarization detecting method which uses a birefringent crystal to encode the two-dimensional Stokes quantities S0~S3 into an image，so that it obtains the information of four Stokes quantities with a single detection. The paper presents the working principle and mathematical model of the polThis paper introduces a new polarization detecting method which uses a birefringent crystal to encode the two-dimensional Stokes quantities S0~S3 into an image，so that it obtains the information of four Stokes quantities with a single detection. The paper presents the working principle and mathematical model of the polarimeter. Also, the reconstructing method，as well as the effect of system parameters is theoretically demonstrated. The encoded image is obtained from numerical simulation according to real system configuration. By using a simple algorithm, we get acceptable reconstructed images which verifies the feasibility and provides references for the design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 211004 (2015)
Terahertz/Visible Dual-Band Image Registration Based on Hybrid Powell Algorithm
Qiao Yulong, Zhao Yuanmeng, Zhang Cunlin, Zhao Yuejin, and Wu Hong
A hybrid algorithm combining improved Powell algorithm with genetic algorithm is proposed for terahertz and visible dual- band image registration from human security check apparatus. Using mutual information as similarity measure to overcome the difficulty of extracting feature points from passive terahertz images. TheA hybrid algorithm combining improved Powell algorithm with genetic algorithm is proposed for terahertz and visible dual- band image registration from human security check apparatus. Using mutual information as similarity measure to overcome the difficulty of extracting feature points from passive terahertz images. The approximate solutions of seven affine transformation parameters are obtained by genetic algorithm and set as the initial point of improved Powell algorithm, and then local search capabilities of improved Powell algorithm are used to obtain the exact solutions of seven transformation parameters. Single genetic algorithm, single Powell algorithm and the proposed hybrid algorithm are respectively used to registrate two groups of terahertz and visible images. Root-mean-square error is used as index to evaluate the registration results.The experimental results show that compared with single genetic algorithm and Powell algorithm, the proposed algorithm can achieve higher matching accuracy. The study can be further used for terahertz/visible dual- band image fusion, to improve the recognition accuracy of concealed object in clothes and enhance the practicability of terahertz human security check apparatus..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 211005 (2015)
A Real Time Imaging Method for Internal Targets of Strongly Scattering Media with High Resolution
Wen Zhengbo, Wu Yulin, Zhang Xiuda, Yan Huimin, and Wei Shaopeng
The scattering effect of strongly scattering medium makes the traditional optical imaging system can not detect the internal targets of scattering medium. To resolve this problem, a method is proposed to real-time detect the object locates in the strongly scattering medium with high resolution. According to the principThe scattering effect of strongly scattering medium makes the traditional optical imaging system can not detect the internal targets of scattering medium. To resolve this problem, a method is proposed to real-time detect the object locates in the strongly scattering medium with high resolution. According to the principle of wave front shaping theory, in condition of convergent lighting, pure phase spatial light modulator is employed to obtain a clear image of a spot target on the surface of the scattering medium. After the illumination is expanded , objects near the pre-corrected point can be clear imaged with a large field of view and a long depth of field with the modulation pattern unchanged. The experimental results prove this method can achieve high acuity real-time imaging. The imaging quality of the traditional optical imaging system without scattering medium and the scattering imaging system with scattering medium is compared. The experimental results show that the scattering imaging system has a better imaging acuity than the conventional optical imaging system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 211006 (2015)
Instrumentation, Measurement and Metrology
High-Accuracy Measurement of Sub-Pixel Image Motion Based on Hybrid Photoelectirc Joint Transform Correlator
Hong Xueting, and Qian Yixian
To measure the sub-pixel image motion which is caused by satellite attitude instability and vibration, an effective approach to measure image motion is presented based on Hybrid Photoelectirc joint transform correlator. Firstly, captured image sequences are optically calculated by joint transform correlator, then the aTo measure the sub-pixel image motion which is caused by satellite attitude instability and vibration, an effective approach to measure image motion is presented based on Hybrid Photoelectirc joint transform correlator. Firstly, captured image sequences are optically calculated by joint transform correlator, then the acquired joint power spectrum is processed by Laplace transform, an improved correlation peak is obtained. Lastly, a modified centroid algorithm is proposed to get more accurate motion measurement. Motion measurement based on optical correlation is discussed, and the optical experimental system is also set up. The experimental results show that the measurement error is as low as 0.03 pixel, the accuracy is improved greatly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212001 (2015)
Three-Dimensional Microsphere Tracking Using Off-Focus Images Based on Cross-Correlation Matching Algorithm
Xie Xiangjun, Lei Hai, Chang Xinyu, Zeng Yanan, Hu Xiaodong, and Hu Xiaotang
To improve the resolution of three-dimensional position measurement of micrometer scale spheres in liquid, especially the resolution in the axial axis, a method named three-dimensional microsphere tracking using off-focus images based on cross-correlation matching algorithm is developed. It is a combination of the crosTo improve the resolution of three-dimensional position measurement of micrometer scale spheres in liquid, especially the resolution in the axial axis, a method named three-dimensional microsphere tracking using off-focus images based on cross-correlation matching algorithm is developed. It is a combination of the cross-correlation algorithm which has high precision matching characteristics to similar images and the idea of tracking three-dimensional microspheres using off-focus images. As a result, the experiments show that a standard deviation of about 0.64 nm is reflected when tracking the same microsphere continuously in the axial direction in four minutes, and a resolution of 1 nm step measurement in all three axes is achieved. This is significant to the study of single biological molecule dynamics and particle image velocimetry etc. Under the same experimental conditions, the comparative measurement and analysis of three-dimensional microsphere tracking with digital in-line holographic microscopy show that the method exhibits high feasibility and resolution in practical measurement applications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212002 (2015)
LED-Based Single Star Simulator with Multi-Color-Temperature and Multi-Star-Magnitude Output
Liu Hongxing, Ren Jianwei, Liu Zexun, Wan Zhi, and Li Baoyong
A LED-based single star simulator system with multi-color-temperature and multi-star-magnitude output is developed to calibrate star sensor′s optical signal, and it can significantly diminish the calibration error caused by the non- matching between star simulator′ s color temperature and star sensor′ s detecting colorA LED-based single star simulator system with multi-color-temperature and multi-star-magnitude output is developed to calibrate star sensor′s optical signal, and it can significantly diminish the calibration error caused by the non- matching between star simulator′ s color temperature and star sensor′ s detecting color temperature. The mechanism of how color temperature′ s non- matching affects star sensor′ s optical signal calibration accuracy is analyzed. The design scheme of LED-based single star simulator is determined, which is divided into four key issues, the determination of light source, the design of drive circuit and control system, the design of color temperature and star magnitude matching algorithm, and the design of control software. The LEDbased single star simulator is calibrated and tested, the spectral matching errors of starlight with 4000 K color temperature, 0 star magnitude and starlight with 7000 K color temperature, 3 star magnitude are 6.37% and 8.76% respectively, and their star magnitudes are 0.03 and 2.93 respectively. The irradiance non-uniformity in Φ100 mm area of LED-based single star simulator is 6.5%. They all meet design requirements..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212003 (2015)
Establishment and Application of Infrared Camera Response Attenuation Model due to Contamination in Satellite
Zhang Yin, Cong Mingyu, and Zhou Yuxing
On- orbit radiometric calibration data from some types of atmospheric radiation measurement satellite are analyzed to investigate the impact of pollutants on the response performance of space- based infrared camera. An attenuation model of camera responded grayscale is established with a clear physical meaning, whose pOn- orbit radiometric calibration data from some types of atmospheric radiation measurement satellite are analyzed to investigate the impact of pollutants on the response performance of space- based infrared camera. An attenuation model of camera responded grayscale is established with a clear physical meaning, whose parameters are fitted using the practical data with the relative root mean square errors less than 1% , and the fitted values coincide with their physical meanings well. In order to determine the pollution tolerance in satellite, rules based on the constraints of camera linear response range and the minimum radiance resolution requirements are proposed, and the recommended decontamination interval of 1250 h is obtained. The method of using the attenuation model to predict calibration coefficients at any moment is presented, and calibration coefficients from model prediction, history calibration tests and the time- matched calibration test are used to convert measuring grayscale data to radiance. Results show that the modelpredicted coefficients can control the calibration errors with less than 3% and are able to improve the measurement accuracy while ensuring image quality..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212004 (2015)
Nano Focusing Method Based on Moire Fringe Phase Analysis
Feng Jinhua, Hu Song, Li Yanli, and He Yu
With the improvement of lithography resolution node, high precision focus detection method becomes more and more important. The focus detection method which is based on moire fringe phase analysis and the triangulation principle is introduced. By analyzing optical modulation of photoelastic modulator and Savart plate, With the improvement of lithography resolution node, high precision focus detection method becomes more and more important. The focus detection method which is based on moire fringe phase analysis and the triangulation principle is introduced. By analyzing optical modulation of photoelastic modulator and Savart plate, adjusting the parallel plate, the light intensity modulation which is caused by focal plane displacement changes in sine or cosine form. By analyzing the experimental data, focusing accuracy of this method is at nanoscale, hard real- time, and non- contact. It can meet the need of projection lithography with the line width of less than 100 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212005 (2015)
Research on Infulence of Acousto-Optic Frequency Shifter to Micro-Doppler Effect Detection
Guo Liren, Hu Yihua, Li Zheng, and Xu Shilong
In order to detect and recognize remote targets based on micro-Doppler effect，the influence of heterodyne lidar system composed by acousto-optic frequency shifters to micro-Doppler feature extraction is researched. Mathematical models between driving power of frequency shifter and signal to noise ratio are established,In order to detect and recognize remote targets based on micro-Doppler effect，the influence of heterodyne lidar system composed by acousto-optic frequency shifters to micro-Doppler feature extraction is researched. Mathematical models between driving power of frequency shifter and signal to noise ratio are established, and simulations and experiments are performed through 1550 nm experimental system to verify their validity. The research shows that within the limiting driving voltage scope, the higher the voltage, the better the detection result is, which is in accordance with the theoretical analysis. Through the contrast experiment，heterodyne detection system is found better than homodyne in time-frequency curve of target feature acquisition. The smaller extracting error and the higher readability indicate that heterodyne system is more conductive than complicated remote target detection..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212006 (2015)
Quasi-Isentropic Compression Experiment with Free Surface in Laser Direct-Drive Condition Based on Shenguang-III Laser Prototype
Wang Feng, Peng Xiaoshi, Xue Quanxi, Xu Tao, and Wei Huiyue
Laser indirect-drive has the potential to get ultra-high pressure which is very useful for shock physics. The isentropic compression experiment with long pulse in laser direct-drive is very sensitive to the laser intensity variation. The important technique for isentropic compression experiment with long pulse in laserLaser indirect-drive has the potential to get ultra-high pressure which is very useful for shock physics. The isentropic compression experiment with long pulse in laser direct-drive is very sensitive to the laser intensity variation. The important technique for isentropic compression experiment with long pulse in laser direct-drive has been introduced with the diagnosis of free surface velocity. The improvement way can be obtained from the experimental data. The target, experimental data and the important technique can be analyzed. The full velocity history of free surface can be achieved after design and control the laser pulse with the comparison of experiment data under 1000 J laser energy. The signal of free surface disappears when the free surface velocity reaches 11.3 km/s. After comparing the simulation data with Multi-1D program and experimental result, the complex of shock wave system in Al sample has been shown because there is no confinement on the free surface. However, this technology is useful to study the main shock wave in the sample. When the sample with transparent window is difficult to manufacture, these experimental data show the technology for the further development of isentropic compression experiment with long pulse in laser direct-drive..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 212007 (2015)
Integrated Optics
Design of a Metallic Waveguide All-Optical Switch Based on Surface Plasmon Polaritons
Shi Zhendong, Zhao Haifa, Liu Jianlong, and Liu Shutian
A novel metallic waveguide Bragg grating all- optical switch based on surface plasmon polaritons (SPP) is proposed using the enhancement and constraint to light by metal- dielectric- metal waveguide Bragg grating. The material and structure size of this switch are decided according to their modulation affection to the A novel metallic waveguide Bragg grating all- optical switch based on surface plasmon polaritons (SPP) is proposed using the enhancement and constraint to light by metal- dielectric- metal waveguide Bragg grating. The material and structure size of this switch are decided according to their modulation affection to the effective refractive index. By adding a metal waveguide filter structure in the switch, the pump and signal light are separated, preventing the disturbance of the pump light to signal light and subsequent light path. The simulation of finite-difference time-domain method results show that the extinction ratio reaches 7.2 dB when the intensity of the pump is 50 MW/cm2, response time is less than 2 ps, and the transverse dimension of this structure is about 400 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 213001 (2015)
Machine Vision
Navigation Line of Vision Extraction Algorithm Based on Dark Channel
Li Yong, and Ding Weili
The farm machinery vision navigation line extraction algorithm is influenced by the external environment, suitability and stability. An algorithm to extract the line for vision navigation based on dark channel is presented. Getting the gray image from the color image using dark channel, then obtaining the two values grThe farm machinery vision navigation line extraction algorithm is influenced by the external environment, suitability and stability. An algorithm to extract the line for vision navigation based on dark channel is presented. Getting the gray image from the color image using dark channel, then obtaining the two values grayscale and filtering it using morphological method and Otsu method, and using the vertical projection method to extract the interested navigation region, next determining the navigation point in the region of interest. The navigation line location is extracted by the least squares fitting. The experimental results show that this method can be applied to different farmlands and road scenes. Compared with the traditional algorithm, the precision can meet the requirements of navigation line, and this method has faster speed. Besides, this method has wider applicability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 215001 (2015)
Adaptive Point Cloud Registration Method Based on Geometric Features and Photometric Features
Wu Mengqi, Li Zhongwei, Zhong Kai, and Shi Yusheng
Multi-view data registration is an important step in the process of large objects three-dimensional (3D) measurement. But the available unmarked 3D surface auto-registration methods can result in unstable registration results when measuring objects with different surface feathers. Aiming to solve this problem, an adaptMulti-view data registration is an important step in the process of large objects three-dimensional (3D) measurement. But the available unmarked 3D surface auto-registration methods can result in unstable registration results when measuring objects with different surface feathers. Aiming to solve this problem, an adaptive 3D autoregistration algorithm is presented based on both geometric and photometric features. In this algorithm. a registration selection model is built to generate a registration judgment factor for synthetically evaluating the complexity of surface geometry and texture. Based on this model, an appropriate registration strategy can be adaptively selected to promise a reliable registration result. Moreover, random sample consensus（RANSAC） algorithm is used to remove the remaining wrong correspondence. The experiments use various registration results to illustrate the performance of the proposed method in different measurement applications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 215002 (2015)
Materials
Optimization of Light Trapping Structure on Textured Silicon Substrate for Heterojunction Solar Cells
Wang Liguo, Zhao Zhenyue, Zhang Xiaodan, Wang Fengyou, Jiang Yuanjian, Du Jian, Zhao Ying, Liu Caichi, Wei Changchun, Xu Shengzhi, and Hao Qiuyan
Silicon heterojunction (SHJ) solar cells as a new high efficient solar cell have been paid much more attention in the past years is prepared by hydrogenated amorphous silicon films deposited on crystalline silicon. The textured structure in high efficiency heterojunction solar cells reduces the reflection and improves Silicon heterojunction (SHJ) solar cells as a new high efficient solar cell have been paid much more attention in the past years is prepared by hydrogenated amorphous silicon films deposited on crystalline silicon. The textured structure in high efficiency heterojunction solar cells reduces the reflection and improves the light trapping. As a result, there is a subsequent higher short circuit current density in the solar cells. Wet chemical etching process is used to obtain texture on monocrystalline silicon substrate. Several key parameters which influence texturing processes, including concentration of isopropyl alcohol, etching time, substrate type and the content of sodium silicate, are selected to optimize and achieve the low reflection on silicon substrate. After that, the reflectance reduces from 34.7% to 9.14% (1011 nm) and the short circuit current density enhances from 32.06 mA/cm- 2 to 36.16 mA/cm- 2. The textured substrate can effectively improve the performance of SHJ solar cells..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 216001 (2015)
Experimental Study of Resonance Characteristics of Split Ring Resonators in Terahertz Band
Ding Yuan, Zhu Junwei, Guo Yuhan, Yuan Zhe, Xu Shiyao, Yang Yi, Zhang Baoshan, and Tang Dongming
The scattering parameters of the micrometer sized split ring resonators (SRR) samples are measured in the frequency range of 0.1 to 2 THz. The incident wave with different polarization directions producs an single electric resonance or both electric and magnetic resonances simultaneously in the normal incidence case. TThe scattering parameters of the micrometer sized split ring resonators (SRR) samples are measured in the frequency range of 0.1 to 2 THz. The incident wave with different polarization directions producs an single electric resonance or both electric and magnetic resonances simultaneously in the normal incidence case. The effect of the material conductivity on the resonant frequency of SRRs is discussed. Based on the simulation results, the relationship between the effective permeability and permittivity and the frequencies are shown, and the curve of resonance frequencies with respect to the different size enlargement factors (k) of the SRR unit is plotted. Both the experimental and the simulation results indicate that the electric and magnetic resonance frequencies linearly depend on 1/k..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 216002 (2015)
Medical Optics and Biotechnology
Influence of Different Defocus Conditions on Vapor Channel Induced by Pulsed CO2 Laser
Li Xuwei, Chen Chuanguo, Zhang Xianzeng, Zhan Zhenlin, and Xie Shusen
The dynamic process of generation, propagation and collapse of vapor channel induced by pulsed CO2 laser is monitored by a high speed camera. The influence of different defocus conditions on vapor channel is investigated. Sequence images of vapor channel process are captured, and coefficients that characterize vapor chThe dynamic process of generation, propagation and collapse of vapor channel induced by pulsed CO2 laser is monitored by a high speed camera. The influence of different defocus conditions on vapor channel is investigated. Sequence images of vapor channel process are captured, and coefficients that characterize vapor channel such as maximum depth are acquired. The results show that different defocus conditions have significant impact on kinetic process of vapor channel. Under pre-focus and focus plane conditions, the shape is similar to a funnel as the vapor channel propagates to the maximum depth, however, under the post-focus condition, the shape is similar to U. The experiment results provide reference for laser medicine, underwater laser processing and energy fields..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 217001 (2015)
Optical Design and Fabrication
Research on the Autonomous Star Sensor Based on Indirectly Sensing Horizon and its Optical Design
Wu Yanxiong, Zhang Xin, Zhang Jizhen, Wang Lingjie, Qu Hemeng, Zhu Yang, and Zeng Fei
Based on stellar refraction indirectly sensing of autonomous navigation for horizon star sensor, a parameter design is analyzed for stellar refraction star sensor which is included by detect waveband, observation field, detect probability and threshold value of magnitude. The field of view (FOV) of star sensor is dividBased on stellar refraction indirectly sensing of autonomous navigation for horizon star sensor, a parameter design is analyzed for stellar refraction star sensor which is included by detect waveband, observation field, detect probability and threshold value of magnitude. The field of view (FOV) of star sensor is divided into two parts of refraction star and unrefraction star. The FOV decreases as orbit attitude increases. Limited by atmosphere absorption, the waveband needs to be 600~900 nm, and the signal-to-noise ratio (SNR) decreases as atmosphere height increases. High sensitive back-thinned charge coupled device (CCD) is applied and athermalizing optical system design is achieved. The result shows that imaging quality is good enough and measure precision of single star sensor achieves 1″, which can meet the requirement of autonomous star sensor measure precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 222001 (2015)
Research and Design of Prefixing Objective with Large Aperture in Imaging Spectrometer
Yu Jiandong, Liang Zhongzhu, Liang Jingqiu, Lü Jinguang, Qin Yuxin, Tian Chao, and Wang Weibiao
Containing stepped micro- mirror and flaky beam splitter, prefixing objective of spatio- temporally modulated Fourier transform imaging spectrometer is not only to match with parameters of ladder micromirror,but also to have telecentric characteristic with a real entrance pupil. To this end, this paper studies a methodContaining stepped micro- mirror and flaky beam splitter, prefixing objective of spatio- temporally modulated Fourier transform imaging spectrometer is not only to match with parameters of ladder micromirror,but also to have telecentric characteristic with a real entrance pupil. To this end, this paper studies a method to transform the ordinary infrared lens into a telecentric construction with a real entrance pupil.Meanwhile, the study of off axis aberrations caused by the sheet beam splitter and compensation plate proposes a correction method applying a combination of cylindrical and Zernike surface to improve image quality. Based on the method, with the specific requirements of 3~5 mm spectral range, F number of 4, 400 mm effective focal length, no vignetting within full field of view of 4.58° , an infrared optical system is designed.Simulation results show that: the image quality of front objective is closed to the diffraction limit with the maximum root mean square (RMS) spot diameter 5.9 mm in full field, and the distortion less than 0.3% . So this method can be used for the design of the front lens with large aperture in spatio-temporally modulated Fourier transform imaging spectrometer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 222002 (2015)
Design of 20× Double-Linkage Continuous Zoom Optical System
Li Hongzhuang, and Zhang Zhenduo
For the complexity of double- linkage zoom system, the design process is settled first, and the visible assist design software is developed. The function of the software includes Guassian optical calculation, compensation curve drawing, aberration and lens size analysis, relative aperture curve output, etc. Using the sFor the complexity of double- linkage zoom system, the design process is settled first, and the visible assist design software is developed. The function of the software includes Guassian optical calculation, compensation curve drawing, aberration and lens size analysis, relative aperture curve output, etc. Using the software, rational Guassian parameters can be selected conveniently, and the relative aperture and its variation of each group can be given, which can help the designer to select the initial configuration. Then utilizing the software, the initial design can performed for a double- linkage zoom system with focal length range from 25mm to 500mm. And through integrated optimization, the system aberration is corrected and balanced. The design results demonstrate that the total optical length is 478 mm, and the modulation transfer function (MTF) at 50 lp/mm for each zoom configuration is higher than 0.6 for center field, and higher than 0.4 for edge field. All indexes satisfy the command of system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 222003 (2015)
Optical Devices
A Dimming Method for RGB LED Based on Three Channels′ PWM
Song Pengcheng, Wen Shangsheng, Shang Jun, Shi Chenyang, and Chen Yingcong
This paper presents a dimming method that based on three channels′ pulse- width modulation (PWM) and light- mixing technology. A quantitative calculation model is established among chromaticity coordinate, correlated color temperature and three channels′ duty cycles. The functional relationship between chromaticity cooThis paper presents a dimming method that based on three channels′ pulse- width modulation (PWM) and light- mixing technology. A quantitative calculation model is established among chromaticity coordinate, correlated color temperature and three channels′ duty cycles. The functional relationship between chromaticity coordinate and maximum luminous flux is also setuped. This method has been verified favorably by light mixing experiments with tricolor LED, which shows that the deviation of chromaticity is less than 2.5% between the theoretical value and the measured value. In addition, the color temperature change of sunlight has been simulated by this quantitative calculation model, and the deviation of CCT is less than 50 K. This model with the advantage of high precision can be applied to various types of LED dimming color and has a beneficial value for practicality..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 223001 (2015)
An Optical Device for On-Line Measurement of Thickness
Xiao Qing, Wang Xinglong, Fu Qian, Zhang Dalong, Liu Xia, Deng Jianqin, and Cao Dingxiang
An optical device based on Michelson interferometer configuration is introduced, which can be used for on-line film thickness measurement. Optical cement is used to splice the glass modules with different lengths and thermal properties, so that the device can make compensation to the environmental temperature variationAn optical device based on Michelson interferometer configuration is introduced, which can be used for on-line film thickness measurement. Optical cement is used to splice the glass modules with different lengths and thermal properties, so that the device can make compensation to the environmental temperature variation. Additionally, the double-fiber collimator which is used to input and output the optical signal and the device containing the glass modules are a whole. So the device will not be disturbed by the environment compared to the other interferometers during testing. The stability of the device is tested by an Agilent wavelength measurement system, and the output interference signal shows the excellent performance that the 95% confidential interval of the variation of the free spectral range (FSR) is ± 0.0005 nm in the disturbed environment (while the acquisition resolution of the Agilent system is 0.001 nm). So we believe this device can be used for on-line interference measurement. To demonstrate the feasibility of the automatic measurement of this device in real- time, the thickness of the cover slice is measured, the result is (177.4 ± 0.7) mm, which is comparable with the commercial thickness measurement equipment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 223002 (2015)
Research of Laser Emission in the Photonic Liquid Crystal Fiber
Wu Rina, Wu Xiaojiao, Wu Jie, and Dai Qin
The random laser radiation is researched by filling the air hole of photonic crystal fiber with dyedoped DCM chiral nematic liquid crystal. At room temperature, by using doubled frequency 532 nm Nd∶YAG laser as optical excitation, the emission spectrum of random laser can be detected in all directions. When the angle bThe random laser radiation is researched by filling the air hole of photonic crystal fiber with dyedoped DCM chiral nematic liquid crystal. At room temperature, by using doubled frequency 532 nm Nd∶YAG laser as optical excitation, the emission spectrum of random laser can be detected in all directions. When the angle between the incident direction of the laser and the axial direction of the sample is 30°, the random laser radiation is obtained in the horizontal direction and vertical direction and a plurality of discrete and sharp random laser radiation peak can be measured in the range from 600 nm to 650 nm, with the line- width of multi- mode peaks less than 0.3 nm. When the sample is heated up to the isotropic temperature, the laser radiation peaks disappear. Among the photonic crystal fiber, the chiral nematic liquid crystal as a strong scattering medium exhibits different molecular orientations and refractive index distributions at various temperatures, which is the fundamental cause of the random laser generation and disappearance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 223003 (2015)
Optics at Surfaces
Plasmon Excitation in C60 Fullerene Dimers Connected by a Sodium Atom
Yin Haifeng, Zeng Chunhua, and Zhang Hong
Plasmon resonances in C60 fullerene dimers connected by a sodium atom are investigated using time-dependent density functional theory. Because of the coupling between alkali metal sodium atom and C60 fullerene, in the infrared spectral region, plasmon resonances emerge in C60 fullerene dimers connected by a sodium atomPlasmon resonances in C60 fullerene dimers connected by a sodium atom are investigated using time-dependent density functional theory. Because of the coupling between alkali metal sodium atom and C60 fullerene, in the infrared spectral region, plasmon resonances emerge in C60 fullerene dimers connected by a sodium atom. With the gradual decrease of the gap between two C60 fullerenes, plasmons of the infrared spectral region firstly show red shift, and then show blue shift. For large gap, the coupling between fullerenes is capacitive, and the plasmon of mid-infrared spectral region is a multipole plasmon resonant mode. For the smaller gap, the plasmon of mid-infrared spectral region gradually evolves into another plasmon resonant mode of near-infrared spectral region due to the electron tunneling. This mode is the coupling of the charge transfer plasmon mode and the multipole plasmon resonant mode..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 224001 (2015)
Quantum Optics
Optimal Solution of Phase-Remapping Attack
Han Baoyuan, and Kong Xiangjin
The plug- and- play structure is bidirectional and stable system in theory. However, the practical system can be attacked effectively due to the imperfect phase modulator. The modified phase- remapping attack is demonstrated. The minimal value of the bit error rate (BER) is derived, which is caused by the modified phasThe plug- and- play structure is bidirectional and stable system in theory. However, the practical system can be attacked effectively due to the imperfect phase modulator. The modified phase- remapping attack is demonstrated. The minimal value of the bit error rate (BER) is derived, which is caused by the modified phase- remapping attack. The effect of the success rate of communication to the practical system is also considered. Under this attack, the BER can be kept the minimum value and a much better success rate of communication can be achieved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 227001 (2015)
Influence of Higher Nonlinearity to Optical Solitons in Electromagnetically Induced Transparency Medium
Du Yingjie, Yang Zhanying, Xie Xiaotao, and Bai Jintao
Effect of higher nonlinearity to optical solitons in the medium of electromagnetically induced transparency is investigated theoretically. By applying semi-classical theory, the response of the medium to the optical field is obtained. Based on the feature of the medium and by using the wave theory, a cubic- quantic nonEffect of higher nonlinearity to optical solitons in the medium of electromagnetically induced transparency is investigated theoretically. By applying semi-classical theory, the response of the medium to the optical field is obtained. Based on the feature of the medium and by using the wave theory, a cubic- quantic nonlinear Schrodinger equation describing the evolution of the optical wave is obtained. The linear and nonlinear susceptibilities of the medium determine the group velocity dispersion parameter, third- order and fifth- order nonlinearities of the nonlinear equation. It is found that the bright soliton and dark soliton can be induced under the presence of higher nonlinearity, and the occurrence of both solitons determined by the signs of the group velocity dispersion and third-order nonlinearity. When the former is negative while the latter is positive, bright soliton occurs; when both of them are negative, dark soliton occurs. The sign of the two parameters can be got by management of the frequency shift between the carrier frequency and the relative atomic transition. Compared with the general nonlinear Schrodinger equation, the cubic- quantic nonlinear Schrodinger equation has tough requirement of input and parameters condition for the occurrence of bright and dark solitons..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 227002 (2015)
Spectroscopy
Study on Real-Time Temperature Measurement Based on Wavelength Modulation Technology
Sun Pengshuai, Zhang Zhirong, Xia Hua, Pang Tao, Wu Bian, Cui Xiaojuan, Shen Fengjiao, Wang Yu, and Dong Fengzhong
Tunable diode laser absorption spectroscopy (TDLAS) has been widely used in the gas concentration and temperature online monitoring because of its excellent characteristics such as fast response, high spectral resolution and non-contact feature. In order to reduce error values and simplify experimental equipments, the Tunable diode laser absorption spectroscopy (TDLAS) has been widely used in the gas concentration and temperature online monitoring because of its excellent characteristics such as fast response, high spectral resolution and non-contact feature. In order to reduce error values and simplify experimental equipments, the temperature inversion theory and derivation formula based on wavelength modulation absorption spectroscopy are analyzed. Two distributed feed back (DFB) lasers with output wavelengths of 760.21 nm and 760.88 nm generate laser covering two oxygen absorption lines with time-sharing sawtooth scanning, respectively. Only one laser beam passes through the same optical path after coupling by a 2×1 fiber coupler. Average temperature in the tube-furnace is obtained by the peak-ratio of second harmonic signals. A method to calibrate required parameters for temperature inversion at indoor temperature is used to correct the impact of line-shape and spectral intensity. The experimental results show that the measured temperatures and the preset values within the temperature of 300 K~900 K are consistent, and the measurement error is within ±20 K..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 230001 (2015)
Study on Influence of X-Ray Beam Spot Intensity on EDXRF Analytical Precision
Qin Xulei, Duanmu Qingduo, Song Zhonghua, Li Ye, Li Shen, Liu Youyin, and Wang Guozheng
When energy dispersive X-ray fluorescence (EDXRF) spectroscopy is used to analyze low-content element in samples with complicated background, interference from X-ray scattering will affect system detection precision, and X-ray scattering is closely related to X-ray beam spot intensity. A shimmer image intensifier is utWhen energy dispersive X-ray fluorescence (EDXRF) spectroscopy is used to analyze low-content element in samples with complicated background, interference from X-ray scattering will affect system detection precision, and X-ray scattering is closely related to X-ray beam spot intensity. A shimmer image intensifier is utilized to collect projection image of X-ray beam spot under different working current and the intensity of mixed and scattered ray around the projection flare is used to characterize X-ray scattering intensity, two methods to reduce X-ray beam spot intensity, i.e. reducing X-ray tube current and collimator diameter, are obtained so as to reduce the impact of the mixed and scattered ray on X-ray. It is found that when the EDXRF method is used to analyze low-content element in samples, the method of reducing collimator diameter is more effective than the method of reducing X-ray tube current for decrease of X-ray scattering, and the system detection precision can be improved when the collimator diameter is reduced and the X-ray tube current is increased meanwhile. The experimental results show that for detecting microelement Cr in the soil, actual relative error of this method is 0.9%~6.6%, and relative standard deviation is 0.7%~1.5%. p is higher than 0.05 in t test, and the test result has no significant difference with standard samples statistically..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 230002 (2015)
A Study on Mechanism of Interactions between DNA and Anthragallol of Madder Color
Gao Yan, Li Junsheng, Li Weilun, Huang Guoxia, and Yan Liujuan
Under the physiological condition that pH is 7.41, the mechanism of interactions between anthragallol (Ant) and deoxyribonucleic acid (DNA) is investigated by ultraviolet- visible spectroscopy and fluorescence spectroscopy using ethidium bromide (EB) as probe. The electrochemical characterization of Ant on glassy carboUnder the physiological condition that pH is 7.41, the mechanism of interactions between anthragallol (Ant) and deoxyribonucleic acid (DNA) is investigated by ultraviolet- visible spectroscopy and fluorescence spectroscopy using ethidium bromide (EB) as probe. The electrochemical characterization of Ant on glassy carbon electrode is determined by cyclic voltammetry. Based on the curves of cyclic voltammetry and the effect of EB on the interactions of Ant with DNA, it is proposed that the binding of Ant to DNA conforms to an intercalative mode. The results show that the binding ratio of Ant and DNA is 3.68:1, the binding constant (K) of Ant with DNA is 2.084×103 L/mol at 25 oC and the apparent molar absorption coefficient (e) is 2.21×104 L·mol-1·cm-1. The influence of salt effect on the interactions of Ant with DNA is studied, and the electrochemical changing rule of Ant is similar to EB with DNA. The results also show that Ant can bind with DNA, intercalation binding is the binding mode between Ant and DNA..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 230003 (2015)
Preparation of Zn Ion Implantation LiNbO3 Crystal and Its Infrared Spectral Properties
Zheng Lijie, Zhang Chuanyi, Zhang Jicheng, Tian Jing, and Su Hong
LiNbO3 samples with different kinds of Zn ions implantation concentration are prepared by ion implantation technology and the influence of Zn ions implantation on the infrared properties of LiNbO3 crystal is also studied. The results show that Zn ions have successfully been implanted into the surface of LiNbO3 crystal LiNbO3 samples with different kinds of Zn ions implantation concentration are prepared by ion implantation technology and the influence of Zn ions implantation on the infrared properties of LiNbO3 crystal is also studied. The results show that Zn ions have successfully been implanted into the surface of LiNbO3 crystal in the form of nanoparticles and the depth is about 80 nm. The pure LiNbO3 crystal occurs the primary and secondary peaks where are in 3486 cm- 1, 2851 cm- 1, 2917 cm- 1, respectively. And the primary absorption peaks of the samples with three different kinds of Zn ions implantation concentration are all in 3483 cm- 1. With respect to pure LiNbO3 crystal, the position of the primary absorption peaks occur slight redshift. The position of the secondary absorption peaks almost do not changes. Zn ions implantation enhances the transmittance of x-cut LiNbO3 crystal, but reduces the transmittance of z-cut LiNbO3 crystal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 230004 (2015)
Research on High Sensitivity Measurement of N2O and CO Based on MIR-QCL and Novel Compact Multi-Pass Gas Cell
Tan Tu, Liu Kun, Wang Guishi, Wang Lei, Chen Weidong, and Gao Xiaoming
A quantum cascade laser (QCL)-based absorption sensor using a novel compact multi-pass gas cell (MGC) for the simultaneous monitoring of CO and N2O is reported. A wide-tunable continuous wave, mode-hopfree external-cavity QCL operating at 4.3 mm is used in the sensor. The QCL can scan over the absorption peaks of N2O (A quantum cascade laser (QCL)-based absorption sensor using a novel compact multi-pass gas cell (MGC) for the simultaneous monitoring of CO and N2O is reported. A wide-tunable continuous wave, mode-hopfree external-cavity QCL operating at 4.3 mm is used in the sensor. The QCL can scan over the absorption peaks of N2O (2203.73333 cm-1) and CO (2203.161 cm-1) within a short scan process (1 s), and achieve the simultaneous detection of N2O and CO. The laser is reflected for 243 times, and the cell has an effective optical path length of 29 m with the physical length of 12 cm. Wavelength modulation spectroscopy with second harmonic (2f) detection is performed to achieve the high sensitivity detection of N2O and CO. The detection limit of this sensor is 2.0 × 10-9 for N2O and 1.7×10-9 for CO..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 230005 (2015)
Ultrafast Optics
Nonlinear Transmittance Based on Transient Behavior of an Ultra-Short Pulse Laser
Chen Sumei, Zhao Peide, Zhang Yong, Fang Zhengji, and Duan Lisong
A partial differential equation (PDE) in the form of transient light intensity is derived for describing the nonlinear absorption of an ultra-short pulse laser in the isotropic dielectric media with only the third order susceptibility. For a Gaussian pulse laser, an analytical solution to PDE is obtained under some appA partial differential equation (PDE) in the form of transient light intensity is derived for describing the nonlinear absorption of an ultra-short pulse laser in the isotropic dielectric media with only the third order susceptibility. For a Gaussian pulse laser, an analytical solution to PDE is obtained under some approximation. The related nonlinear transmittance depends on not only the peak intensity of the pulse laser, sample thickness and two-photon absorption coefficient, but also the frequency and the full width at half maximum (FWHM) of a laser pulse. The simulations of the experimental results of the materials such as Rhodamine show that the two-photon absorption coefficients of the media based on the approximate solution to PDE are generally lager than the ones based on the existing nonlinear transmittance, which are qualitatively the same as the conclusion given by fluorescence method. The results suggest that the active nonlinear transmittance may have some deviations due to the absence of the reasonable deals with the transient behavior of an ultra fast laser..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 232001 (2015)
Vision, Color, and Visual Optics
Depth Anti-Aliasing Algorithm Based on Classified Mapping for Volumetric True-3D Display
Fang Yong, Zhang Yingsong, Wu Huaxia, Lü Guoqiang, and Hu Yuehui
To solve the problem of depth discontinuity of three-dimensional (3D) images having steep surface on imaging depth direction when using current multi-planar anti-aliasing technique, a depth anti-aliasing algorithm based on classified mapping is proposed. As the imaging of solid-state volumetric true-3D display is charaTo solve the problem of depth discontinuity of three-dimensional (3D) images having steep surface on imaging depth direction when using current multi-planar anti-aliasing technique, a depth anti-aliasing algorithm based on classified mapping is proposed. As the imaging of solid-state volumetric true-3D display is characteristic of three-dimensional surface, two-dimensional curves generating from interception of YOZ (or XOZ) planar and three-dimensional surface are analyzed. A method of voxel decomposition based on adjacent multi-layers mapping is introduced, which conforms with human stereoscopic vision, as well as a type judgment algorithm of voxel mapping. The off-axis viewing angles under the conditions of depth continuity are expanded to some extent by means of self-adapted classified mapping of raw voxels. A solid-state volumetric true-3D display system is developed, and 3D images are tested on the system. The result shows that most 3D images have completely smooth surfaces out to large off-axis viewing angles (about 45° ), and a good depth continuity can be obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 233001 (2015)
X-Ray Optics
Numerical Simulation of Polycapillary X-ray Lens
Peng Shiqi, Liu Zhiguo, Sun Tianxi, Wang Kai, Yi Longtao, Yang Kui, and Chen Man
To optimize the design and fabricate the X- ray lens, the method of rotating coordinate system is used to establish the equation of the tubes. Some mathematical transformations and formulae are used instead of iterative method to find out the intersection of the X- ray and the wall of the capillary, so that X- ray′ s tTo optimize the design and fabricate the X- ray lens, the method of rotating coordinate system is used to establish the equation of the tubes. Some mathematical transformations and formulae are used instead of iterative method to find out the intersection of the X- ray and the wall of the capillary, so that X- ray′ s trajectory can be traced. The transmission rule of the X- ray propagation in the X- ray lens can be got, after tracing a large number of X- ray beams. A program based on ray- tracing method is designed to simulate the transmission efficiency of the X- ray lens and the light spot gained from it. Two parallel lenses are tested to verify the rationalization of the model. As to the transmission efficiency, the experimental result is 13.0% and the simulation result is 14.2% when the energy of the photon is 8.05 keV. And there is a notable similarity between optical and simulated images of the light spot. The results show that the mathematical model is reasonable, and it has the potential of designing and fabricating X-ray lenses..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 234001 (2015)
Total Variation Constrained Iterative Filtered Backprojection CT Reconstruction Method
Ma Jiming, Zhang Jianqi, Song Guzhou, Wang Qunshu, Han Changcai, and Duan Baojun
Reconstruction algorithm is the core technology in computerized tomography (CT). It is intractable to utilize priori information and constraint condition in analytical CT reconstruction algorithm. To resolve the problem, by analyzing the principle of the filtered backprojection (FBP) reconstruction algorithm, the relatReconstruction algorithm is the core technology in computerized tomography (CT). It is intractable to utilize priori information and constraint condition in analytical CT reconstruction algorithm. To resolve the problem, by analyzing the principle of the filtered backprojection (FBP) reconstruction algorithm, the relationship between the ideal CT image and the reconstructed CT image is proposed, an iterative method based on FBP is put forward. To suppress the spot artifacts induced by the iterative algorithm, a total variation (TV) model is introduced into the procedure and a TV constrained iterative filtered backprojection is built. In numerical simulation, images reconstructed by this method show high consistency with the ideal image, whether the sinograms are ideal, sparse, metal or limited angle. The results indicate that it is an adaptable and high precision CT reconstruction method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 2, 234002 (2015)
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