Contents
2012
Volume: 32 Issue 5
50 Article(s)
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Atmospheric Optics and Oceanic Optics
Atmospheric Turbulence Phase Screen Simulation Based on Random Unit Expansion
Hua Zhili, and Li Hongping
Accurately generating the phase screen (PS) is a key step to numerical simulation of the atmospheric turbulence. According to the statistical characteristics of turbulence, a new method called random unit expansion mainly focusing on the scale distribution randomness and small scale phase fluctuation of turbulence is iAccurately generating the phase screen (PS) is a key step to numerical simulation of the atmospheric turbulence. According to the statistical characteristics of turbulence, a new method called random unit expansion mainly focusing on the scale distribution randomness and small scale phase fluctuation of turbulence is induced by use of the phase structure function (PSF). Based on the PS generated, Kolmogorov atmospheric turbulence model is obtained. Expansion result shows that the phase structure function derived from the simulation is very close to the ideal one. Compared with power spectrum method, performance in low-frequency part is better. Meanwhile, as the grid number of PS increases, characteristic in high frequency part appears obviously and gradually closer to the ideal function. To evaluate the accuracy of the atmospheric turbulence numerical model, scintillation ratio is computed. In the condition of weak and moderate turbulence, the simulated result agrees with theoretical one, while to the strong turbulence, max relative error will be about 40%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 501001 (2012)
Optical Model of Image Degradation in Atmospheric Inhomogeneous Path
Wu Pengfei, Xu Qingshan, Fang Shuai, and Rao Ruizhong
The optical model of image degradation in homogeneous path is widely used in restoration of degraded image in atmosphere. However, when observing in slant path, the illumination and optical characteristic are inhomogeneous in the path of sight. This also occurs even though in horizontal path. The optical model of imageThe optical model of image degradation in homogeneous path is widely used in restoration of degraded image in atmosphere. However, when observing in slant path, the illumination and optical characteristic are inhomogeneous in the path of sight. This also occurs even though in horizontal path. The optical model of image degradation in inhomogeneous path is founded based on radiative transfer theory of the parallel plane atmosphere, and the simulation analysis on the model under typical atmospheric and observing conditions is performed. From the results, the degradation model in inhomogeneous path is reduced to the model in homogeneous path when observing near horizontally. While the observing distance is short, the two models are consistent in expression form. And compared with longer wavelengths, the conclusion is better satisfied at shorter wavelengths. The effect of different azimuthal angle differences on degradation model lies only in the difference of background skylight in the position of observer. In addition, the degradation model depends on the near-ground horizontal visibility..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 501002 (2012)
Study on Effect of Polarization Filter for Suppressing Sky Background Light in Daytime
Zhang Ruijin, Xian Hao, Rao Changhui, Zhang Xuejun, and Zhang Ang
Most of adaptive optics systems work in nighttime. Polarization filter technique is applied to suppress sky background for detecting the weak objects in daytime. The theory of polarization filter is introduced. Different kinds of polaroid sheets are placed between the adaptive optics system and the secondary mirror of Most of adaptive optics systems work in nighttime. Polarization filter technique is applied to suppress sky background for detecting the weak objects in daytime. The theory of polarization filter is introduced. Different kinds of polaroid sheets are placed between the adaptive optics system and the secondary mirror of 1.8 m telescope in Lijiang observation station. Experimental results indicate that polarization filter technique can suppress sky background light effectively and improve the detectability of adaptive optics system. It is shown that polarization filter technique can be used for observing the stellar stars in daytime..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 501003 (2012)
Coherence and Statistical Optics
Ghost Imaging Based on Sparse Array Pseudothermal Light System
Chen Mingliang, Li Enrong, Wang Hui, Shen Xia, Gong Wenlin, and Han Shensheng
Great breakthroughs have been made in research of ghost imaging in recent years. The application value of ghost imaging is increasingly obvious. The precondition of ghost imaging is that its light source should be random fluctuating thermal light. Presently, pseudothermal light is usually generated by passing a laser bGreat breakthroughs have been made in research of ghost imaging in recent years. The application value of ghost imaging is increasingly obvious. The precondition of ghost imaging is that its light source should be random fluctuating thermal light. Presently, pseudothermal light is usually generated by passing a laser beam through a revolving ground glass. In view of the limitations of such a method, this paper proposes to generate pseudothermal light via sparse array independent source combining system, and discusses the differences between two algorithms, i.e., linear correlation algorithm and sparsity constraint nonlinear algorithm, in ghost imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 503001 (2012)
Diffraction and Gratings
Modified Algorithm for Designing of Diffractive Optical Element to Decrease the Phase Singular Spots
Lü Yanfei, Dong Yuan, Li Shutao, Li Qingsong, Jin Guangyong, and Zhang Xihe
A new modified Gerchbery-Saxton (G-S) algorithm based on the technology of the digital image processing to decrease the phase singular spots is presented. The comparisons of the new modified G-S algorithm to the ordinary G-S algorithm are made, and the results show that the new modified G-S algorithm has the ability ofA new modified Gerchbery-Saxton (G-S) algorithm based on the technology of the digital image processing to decrease the phase singular spots is presented. The comparisons of the new modified G-S algorithm to the ordinary G-S algorithm are made, and the results show that the new modified G-S algorithm has the ability of making the phase distribution curve sleek and further decreasing. Finally, the phase distribution of the diffractive optical elements needed as the hollow beams are transformed from Gaussian beams is obtained by this algorithm, 8.31% RMS error is achieved and the phase values of about 33.2% of the total pixels are modified which make the curve of phase distribution of the diffractive optical elements sleek for ease of microprocessing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 505001 (2012)
Fiber Optics and Optical Communications
Water Sound Sensor Using the Optical Fiber Grating Sensitivity Enhanced Through Side Pressure and End Surface Pulling
Li Dongming, Chen Jun, Ge Huiliang, and Sang Weibing
Hydroacoustic sensor of the passive optical fiber grating sensitivity enhanced through side pressure and end surface pulling is investigated. The filling and the elastic slice is used to enhance the sensitivity of the optical fiber grating sensor. The research results indicate that the resonance frequency using the filHydroacoustic sensor of the passive optical fiber grating sensitivity enhanced through side pressure and end surface pulling is investigated. The filling and the elastic slice is used to enhance the sensitivity of the optical fiber grating sensor. The research results indicate that the resonance frequency using the filling method is too low (300 Hz), and high frequency sensitivity is too low (<-205 dB) too. The technology is complex. The Be-Cu (beryllium-copper) elastic slice is used to enhance sensitivity. In a frequency range of 100~1000 Hz the sensitivity reaches (-175±2) dB. The casing of the enhanced sensitivity sensor is made and applied to water sound detection. The results indicate that its sensitivity and frequency response can meet the application requirement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 506001 (2012)
Large-Separation Dual-Peak Filtering Characteristics of Phase-Shifted Long-Period Fiber Gratings with Film Coatings
Chen Haiyun, Gu Zhengtian, and Yang Ying
The large-separation dual-peak filtering characteristics of phase-shifted long-period fiber gratings (PS-LPFG) with film coatings are studied. When an LPFG is designed to work at the phase-matching turning point (PMTP), the coupling between core mode and a higher-order cladding mode produces a single resonant peak whosThe large-separation dual-peak filtering characteristics of phase-shifted long-period fiber gratings (PS-LPFG) with film coatings are studied. When an LPFG is designed to work at the phase-matching turning point (PMTP), the coupling between core mode and a higher-order cladding mode produces a single resonant peak whose bandwidth reaches 288 nm and above. The introduction of a phase-shift into the center of this LPFG gives rise to two band-rejection peaks locating at the two sides of the central wavelength. The separation between these two peaks reaches 388 nm which is much larger than that of the PS-LPFG based on the coupling between core mode and a lower-order cladding mode. When the LPFG is devised uniformly by introducing M (M>1) π phase shifts, the separation increases with the increase of M. The loss at central wavelength is constant at zero when M is odd, whereas the loss at central wavelength decreases with the increase of M when M is even. The increase of film thickness and refractive index causes the two peaks to shift towards short wavelength and increases the separations. Furthermore, the increment of grating length changes the peak loss of dual peaks and decreases the separation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 506002 (2012)
40 Gb/s Reconfigurable All-Optical Logic Gate Based on Nonlinear Optical Loop Mirror
Wang Wenrui, Yu Jinlong, Luo Jun, Han Bingchen, Guo Jingzhong, Wang Ju, Liu Yi, and Yang Enze
All-optical ultra-fast and reconfigurable logic gates have been implemented by exploiting simple and low-cost schemes based on nonlinear optical loop mirrors (NOLM). Conventional NOLM-based all-optical logic gates utilize the self-phase modulation effects or cross-phase modulation effects. Thus, types of logic gates thAll-optical ultra-fast and reconfigurable logic gates have been implemented by exploiting simple and low-cost schemes based on nonlinear optical loop mirrors (NOLM). Conventional NOLM-based all-optical logic gates utilize the self-phase modulation effects or cross-phase modulation effects. Thus, types of logic gates that can be achieved are limited by the low degree of freedom in reconstruction of the transmission function. Here, an improved scheme of NOLM-based all-optical logic gate is proposed by exploiting the nonlinear polarization rotation in the NOLM. The evolution of the polarized state of light is analyzed as well as the effect of the polarization of the input light and the polarization controller in NOLM. Theoretical analysis and numerical simulation results show that all the basic logic gates can be realized using a single NOLM structure, only by adjusting the polarization controller. Because it is more free to rebuild the transmission function when the nonlinear polarization rotation effect is taken into account. We demonstrate the feasibility of the scheme experimentally by realizing all-optical logic gates of “NOT”, “AND”, “OR”, “NOR”, “XOR”, “NXOR” at 40 Gb/s operation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 506003 (2012)
Influence and Suppression of Coherent Rayleigh Noise in Fiber-Optic-Based Phase-Stabilized Microwave-Frequency Transmission System
Chang Le, Dong Yi, Sun Dongning, Zhang Damin, Xie Weilin, and Hu Weisheng
Distribution of phase-stabilized microwave frequency reference over a wide area is a key technology in a variety of applications including long-baseline interferometry for radio astronomy, fundamental physics metrology and multi-static radar system. Based on the round-trip phase correction, a theory model of phase-stabDistribution of phase-stabilized microwave frequency reference over a wide area is a key technology in a variety of applications including long-baseline interferometry for radio astronomy, fundamental physics metrology and multi-static radar system. Based on the round-trip phase correction, a theory model of phase-stabilized microwave frequency reference distribution through optical fiber with opto-electronic delay locked-loop is established. Theoretical and experimental efforts are made to investigate the influence of the coherent Rayleigh-scattering noise on the system stability. Coherent Rayleigh-scattering noise not only leads to degradation of signal-to-noise rotio, but also further degrates the stabiling of remote signal by transforming phase locked loop into residual phase noise, which is the key factor of phase-stabihzed transmission. A dual wavelength transmission technology is proposed to overcome its influence, the concept by transmitting a 10 GHz microwave frequency reference over 100 km single-mode fiber is demonstrated, and the root mean square-jitter is measured under 730 fs at the remote end..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 506004 (2012)
Fourier Optics and Signal Processing
Research for Fast Spectrum Recovery Algorithm of PEM Nonequiphase Phase Interference Signal
Wang Mingyan, Wang Zhibin, Zhang Jilong, Zhang Mingjuan, Chen Youhua, and Jing Ning
In the photoelastic modulator-Fourier transform spectrometer (PEM-FTS), because the modulation optical path difference is nonlinear, the fast Fourier transform (FFT) cannot be directly used for spectrum recovery, and direct computing cost is too much. The phase of PEM interference signal is simulated by Matlab with theIn the photoelastic modulator-Fourier transform spectrometer (PEM-FTS), because the modulation optical path difference is nonlinear, the fast Fourier transform (FFT) cannot be directly used for spectrum recovery, and direct computing cost is too much. The phase of PEM interference signal is simulated by Matlab with the non-uniform fast Fourier transform algorithm (NUFFT), and then the core of the spectrum information processing system is designed with TMS320C6713 floating-point digital signal processer (DSP), finally, it realized the real-time processing of the spectrum on hardware. The result shows that the algorithm for spectrum recovery has some advantages, such as fast running speed, high accuracy and so on. 1024 point spectrum recovery speed is 20 times more than direct operation speed, recovery precision can reach 0.78%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 507001 (2012)
Instrumentation, Measurement and Metrology
Measurement Technique on Nanoparticles with Laser-Diode Self-Mixing Interferometry Based on Bandpass Filters
Zhang Qiuchang, Shen Jianqi, Wang Huarui, and Chen Xianqing
The laser-diode self-mixing interferometry can be employed to measure the sizes of nanoparticles. The standard nanoparticles whose sizes are labeled as 180, 100 and 60 nm are measured and the corresponding power spectra of the self-mixing signals are obtained with a series of bandpass filters. As a comparison, the poweThe laser-diode self-mixing interferometry can be employed to measure the sizes of nanoparticles. The standard nanoparticles whose sizes are labeled as 180, 100 and 60 nm are measured and the corresponding power spectra of the self-mixing signals are obtained with a series of bandpass filters. As a comparison, the power spectral densities (PSD) are achieved from the Fourier transform of the self-mixing signals which are recorded in real time. With the inversion algorithm, the particle-size distributions are extracted from either the PSD or the power spectra with bandpass filters (PS-BPF). It is showed that the particle-size distributions obtained from these two methods agree with each other and consist satisfactorily with those measured by the commercial particle-size analyzer. The analysis on the illness condition of modal matrices of these methods indicates that the technique based on bandpass filters is better than that based on the PSD..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512001 (2012)
Fast Algorithms on Center Location of Two Dimensional Gaussian Distribution Spot
Feng Xinxing, Zhang Liyan, Ye Nan, and Yang Bowen
The Gaussian surface fitting (GSF) is considered to be an excellent target location algorithm with high precision. But it is too expensive in computation to be utilized in real-time applications, such as dynamic tracking, dynamic measurement and autonomous navigation. By dividing the coordinate of the spot center into The Gaussian surface fitting (GSF) is considered to be an excellent target location algorithm with high precision. But it is too expensive in computation to be utilized in real-time applications, such as dynamic tracking, dynamic measurement and autonomous navigation. By dividing the coordinate of the spot center into integer pixel value and subpixel value, a new fast algorithm, named Gaussian surface analyzing (GSA) is deduced, in which the center is located with analytical formulas and the intensity values of all pixels in the region of interest (ROI). In addition, an improved version of the traditional GSF algorithm, called fixed-coefficient Gaussian fitting (FCGF) is proposed as well, in which the expensive computation of the generalized inverse matrix is avoided. Compared to the GSF, the GSA and the FCGF have similar performanece in accuracy and robustness, however their running time is no more than 1/278 and 1/78 of the GSF respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512002 (2012)
Fringe Reflection Photogrammetry Based on Pose Estimation with Free Planar Mirror Reflection
Xiao Yongliang, Su Xianyu, and Chen Wenjing
Since liquid crystal display (LCD) screen locates outside of the camera′s field of view in fringe reflection photogrammetry, fringe is obtained through specular reflection by a fixed camera. Thus, the pose calibration between camera and LCD screen is the main challenge in fringe reflection photogrammetry. A markerless Since liquid crystal display (LCD) screen locates outside of the camera′s field of view in fringe reflection photogrammetry, fringe is obtained through specular reflection by a fixed camera. Thus, the pose calibration between camera and LCD screen is the main challenge in fringe reflection photogrammetry. A markerless planar mirror is used to reflect the LCD screen 3 times, and the fringe is mapped into camera. The geometrical calibration can be accomplished by estimating the pose between the camera and virtual image of fringe. With the help of the relation beween their pose, incidence and reflection ray can be unified in the camera frame, triangulation can be operated in the camera frame to measure 3D shape of specular. Results of simulations and experiments demonstrate that the approach is simple, feasible and has high accuracy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512003 (2012)
Double-Step Phase-Shifting Algorithm for Fringe-Projection Measurement
Zheng Dongliang, and Da Feipeng
Double three-step phase shifting algorithm (PSA) works well in reducing the measurement error for a digital fringe projection profilometric system. Based on theoretical analysis and experiments, double four-step PSA and double five-step PSA are proposed. In addition, a new method to average two obtained phase maps and Double three-step phase shifting algorithm (PSA) works well in reducing the measurement error for a digital fringe projection profilometric system. Based on theoretical analysis and experiments, double four-step PSA and double five-step PSA are proposed. In addition, a new method to average two obtained phase maps and to generate the correct phase map is presented, which is simple and effective for double-step PSA. Experiment verifies the correctness of double four-step PSA and double five-step PSA which can reduce much more measurement error than double three-step PSA in the practical applications. The advantages of three-step, four-step and five-step PSA are kept through projecting double the number of fringe patterns which are needed for traditional phase shifting algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512004 (2012)
Study of Photoelastic Stress Distribution and Imaging Method Based on Stokes Parameters
Li Zhicheng, Tang Zhilie, Chen Ping, and Chen Feihu
A measuring and imaging method based on Stokes parameters with a division-of-amplitude polarimeter (DOAP) is presented. The theoretical calculation and parameters measurement are investigated. A DOAP system is designed and calibrated by Equator-Poles (E-P) method. Then, the Stokes parameters can be measured rapidly by A measuring and imaging method based on Stokes parameters with a division-of-amplitude polarimeter (DOAP) is presented. The theoretical calculation and parameters measurement are investigated. A DOAP system is designed and calibrated by Equator-Poles (E-P) method. Then, the Stokes parameters can be measured rapidly by use of four photoelectric detectors with the same performance. The Stokes parameters of monochromatic linearly polarized light that passed through the photoelastic sample are measured with the DOAP. Then the phase retardation between the emergent and incident polarized light is calculated and the stress value in the sample is obtained. A plate glass sample and an organic glass sample, which is subjected to axial compressive load, are scanned with this method separately, and their stress distribution are obtained. The experimental results show that, this method can measure the stress at any position of the photoelastic sample accurately, rapidly and nondestructively. It′s a real time measuring method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512005 (2012)
Compensating Algorithm for the Nonlinear Phase-Shift Error for Phase-Shifting Shadow Moiré Technique
Du Hubing, Zhao Hong, Li Bing, Zhao Jinlei, and Cao Shixu
Due to the nonlinear nature of height-phase relation, the traditional phase shifting shadow Moiré can only be fulfilled under certain approximations. Thus a systematic error source is introduced. Therefore, a general phase extraction algorithm with arbitrary phase step based on iterative self-tuning algorithm is pDue to the nonlinear nature of height-phase relation, the traditional phase shifting shadow Moiré can only be fulfilled under certain approximations. Thus a systematic error source is introduced. Therefore, a general phase extraction algorithm with arbitrary phase step based on iterative self-tuning algorithm is proposed. In the proposed method, the estimation of phase shift is calibrated by the least squares fitting in spatial domain. Then, the accurate phase is obtained by an iterative process. Numerical experiments show that the proposed method can effectively minimize the nonuniform phase-shift error and can determinate the precise phase shifts during the process of demodulation. In the noisy case, the calibration error of the proposed is less than 3.4%. The experimental results prove the effectiveness of this technique. The proposed method improves measurable depth range..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512006 (2012)
Camera Radial Distortion Calibrating Method Based on Moving Characteristic Target
Wang Huifeng, and Wang Bingjian
In order to reduce the measurement error caused by camera radial distortion in measurement system based on image, a new distortion calibration method is designed, resorting to characteristic concentric circles target. A character target rode on a two-dimensional fine platform is situated in a known position of the objeIn order to reduce the measurement error caused by camera radial distortion in measurement system based on image, a new distortion calibration method is designed, resorting to characteristic concentric circles target. A character target rode on a two-dimensional fine platform is situated in a known position of the object side which is vertical to the optical axis, then the target images are collected and processed. A least square arithmetic is introduced to compute the fitting radius according to which the characteristic target is moved in a scheduled mode until the radius is maxim or in the demanded range. At the very time the center of the concentric circles is the camera distortion center, the coefficients of the distortion polynomial are gotten recurring to relation of arithmetical radius and imaging model radius of the camera. To find the distortion center coordinate rapidly, a coordinate alternating optimization arithmetic is applied. Experimental results show that the precision of the camera radial distortion center location demarcating can reach 0.6 pixel, and the repeated error of significant figures for polynomial coefficients is less than 0.02, and all can be realized with one character target. The distorted image can be corrected perfectly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512007 (2012)
Windowed Fourier Transform Profilometry Based on Advanced S-Transform
Dong Fuqiang, Da Feipeng, and Huang Hao
An adaptive windowed Fourier transform (WFT) profilometry based on the ridge algorithm of S-transform is presented. The practical use of one-dimensional S-transform in processing fringe pattern is discussed, and the S-transform expression is derived. Every point′s instantaneous frequency is calculated by taking advantaAn adaptive windowed Fourier transform (WFT) profilometry based on the ridge algorithm of S-transform is presented. The practical use of one-dimensional S-transform in processing fringe pattern is discussed, and the S-transform expression is derived. Every point′s instantaneous frequency is calculated by taking advantages of S-transform′s frequency sensitivity and its ridge idea. The influence of φ″(b) on the ridge of S-transform is derived in the sharp phase transition region, and a more accuracy instantaneous frequency is calculated after removing this deviation. Then an accurate phase map of fringe pattern is calculated by using the windowed Fourier transform based on the window which is the reciprocal of instantaneous frequency. Finally, the simulation which compares the accuracy of phase map calculated by WFT based on S-transform (SWFT) before and after removing the influence from deviation of φ″(b) is carried out. Experiments show its advantages in anti-noise and accuracy of the wrapped phase comparing to WFT based on wavelet-transform (WWFT)..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512008 (2012)
Research on Detection Technology of Bio-Aerosols with Tryptophan Intrinsic Fluorescence Measurement
Cai Shuyao, Zhang Pei, Zhu Linglin, Xie Chengke, Sun Zhengyu, Cheng Weilin, Zhao Yongkai, and Huang Huijie
Bio-aerosols are closely related to environment quality and human health. Aerosol detection technology with optical measurement method, which is rapid, nondestructive and sensitive, becomes to the mainstream of research. So far, there is no national standard about the evaluation and calibration method to the detection Bio-aerosols are closely related to environment quality and human health. Aerosol detection technology with optical measurement method, which is rapid, nondestructive and sensitive, becomes to the mainstream of research. So far, there is no national standard about the evaluation and calibration method to the detection system. Based on the measurement of intrinsic fluorescence, a set of bio-aerosol detection equipment including virus aerosols is developed, with which a method of calibration is proposed using tryptophan as the target. The experimental results show a good linear response between the detection equipment to tryptophan aerosol with an excellent correlation (R2≥0.99), the sensitivity of 4000 L-1. The research demonstrates the reliability of the bio-aerosol fluorescence detection by measuring the content of tryptophan. Further more, the feasibility of prejudgment to the species of bio-aerosol particles with the multi-channel fluorescence detection technology is discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 512009 (2012)
Lasers and Laser Optics
Laser Beam Shaping Based on Liquid-Crystal Spatial Light Modulator
Yu Xiaochen, Hu Jiasheng, and Wang Lianbao
A hybrid algorithm based on the phase mixture algorithm (PMA) and profile-smoothing algorithm is used for laser beam shaping, reducing mean square error and nonuniformity of output beam at the same time. Using the phase-modulation characteristics of liquid-crystal spatial light modulator (LCSLM), an experimental opticaA hybrid algorithm based on the phase mixture algorithm (PMA) and profile-smoothing algorithm is used for laser beam shaping, reducing mean square error and nonuniformity of output beam at the same time. Using the phase-modulation characteristics of liquid-crystal spatial light modulator (LCSLM), an experimental optical system is built up. The input Gaussian laser beam is shaped to flat top circular beam and rectangle beam respectively. The top beam nonuniformity and mean square error of the output beams received by CCD are less than 5%, and the energy concentration is higher than 90%. This mehod is proved to be a real-time, controllable and efficient laser beam shaping method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 514001 (2012)
Attenuation of Self-Mixing Interference Signal of Laser Diode with External-Cavity Length
Hu Xianfeng
Characteristics and laws of the variation of self-mixing interference signal of laser diode along with the increase of external-cavity length are analyzed theoretically. The self-mixing interference signal attenuating exponentially along with increase of external-cavity length is deduced from the composite cavity interCharacteristics and laws of the variation of self-mixing interference signal of laser diode along with the increase of external-cavity length are analyzed theoretically. The self-mixing interference signal attenuating exponentially along with increase of external-cavity length is deduced from the composite cavity interference function. The attenuation coefficient is direct ratio to imaginary part of light frequency. A group of transcendental equations for imaginary part and real part of light frequency are also presented. By solving the equations, at external-cavity length more than a critical value, along with the increase of external-cavity length, the imaginary part is inversely proportional to attenuation, so the self-mixing interference signal attenuates very slowly. When external-cavity length is less than the critical value, feedback light increases the imaginary part, moreover, the imaginary part oscillates along with external-cavity length. The self-mixing interference signal appears as a complicated state. The greater the intensity of the external cavity feedback or the single-mode line-width of laser is, the smaller the critical value is. Analysis of the laser diode self-mixing interference also needs to consider the effect of feedback light on the imaginary part..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 514002 (2012)
Machine Vision
Monocular Multi-Viewpoints Stereo Imaging and Application
Song Zhendong, and Jiang Wei
A monocular imaging system is designed to capture the multi-viewpoints stereo images. Several identical isosceles trapezoidal planar mirrors are placed around a wide view-angle camera. The light rays from an object projected onto the camera include direct light and the light reflected by the mirrors, and divide the camA monocular imaging system is designed to capture the multi-viewpoints stereo images. Several identical isosceles trapezoidal planar mirrors are placed around a wide view-angle camera. The light rays from an object projected onto the camera include direct light and the light reflected by the mirrors, and divide the camera′s image into several regions; thus a multi-viewpoints image is captured. These regions correspond to observations with multiple cameras at different positions and orientations, and can be used for multi-views stereo images to reconstruct three-dimensional (3D) information. The system design guideline and calibration method are described, and an application of 3D shape measurement is proposed. Experimental results indicate that the proposed system can capture monocular multi-viewpoints stereo images, and achieve highly robust 3D measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 515001 (2012)
Moving-Objects Interaction Recognition Based on the Spatial-Temporal Semantic Information
Jin Biao, Hu Wenlong, and Wang Hongqi
A method for recognizing human-human interaction is proposed based on the spatial-temporal semantic information. Different from traditional methods to model the interactions, this framework achieves recognizing activities based on the transformation of the spatial semantic meaning. First, with detection and tracking reA method for recognizing human-human interaction is proposed based on the spatial-temporal semantic information. Different from traditional methods to model the interactions, this framework achieves recognizing activities based on the transformation of the spatial semantic meaning. First, with detection and tracking results, the spatial semantic meaning (front, back, face to face, back to back, and left or right) between the persons are extracted based on motion directions and spatial relationships (including topological and directional relations). Then, stochastic context-free grammar is used to recognize interactions that the rules are learned based on the transformation of spatial semantics. Extensive experiments have been executed to validate the effectiveness of the proposed approach, and the method can recognize the interactions without additional training..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 515002 (2012)
Materials
Application of the Novel Porous Gel Electrolyte in Flexible Quasi-Solid-State Dye-Sensitized Solar Cell
Li Qinghua, Wang Yingmin, Li Wenjie, Zhang Tingting, Cai Li, Cheng Zexiu, and Li He
A novel gel polymer electrolyte based on poly(acrylic acid-g-CTAB)-polypyrrole is prepared. Based on the gel electrolyte, a flexible quasi-solid-state dye-sensitized solar cell (DSSC) is fabricated by using a low-temperature filming technique. The researches by scanning electron microscopy, thermal degradation analysisA novel gel polymer electrolyte based on poly(acrylic acid-g-CTAB)-polypyrrole is prepared. Based on the gel electrolyte, a flexible quasi-solid-state dye-sensitized solar cell (DSSC) is fabricated by using a low-temperature filming technique. The researches by scanning electron microscopy, thermal degradation analysis and cyclic voltammetry show the effect of the gel polymer electrolyte on flexible DSSC. Owing to high conductivity and the catalytic function of polypyrrole for I-/I-3 redox reaction for the gel electrolyte, the flexible quasi-solidstatedye-sensitized solar cell shows a light-to-electric energy conversion efficiency of 1.28%, under simulated solar light irradiation with intensity of 100 mW/cm2 [air mass (AM) 1.5]..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 516001 (2012)
Photonic Band Gap Splitting Based on Optical Tamm States of Photonic Crystal
Chen Zefeng, Han Peng, and Chen Yihang
Two kinds of one-dimensional photonic crystals are repeated alternatively to construct the superlattice structure. The energy-band structures and transmission spectra of the superlattice are analyzed. Results show that multiple interface tunneling modes emerge and they couple each other to form a new pass band. As the Two kinds of one-dimensional photonic crystals are repeated alternatively to construct the superlattice structure. The energy-band structures and transmission spectra of the superlattice are analyzed. Results show that multiple interface tunneling modes emerge and they couple each other to form a new pass band. As the periods of the one-dimensional photonic crystals vary, the width of the transmission band changes while the position of the band remains invariant. For specific periods of the photonic crystals, the pass band will split and a zero-phase or π-phase gap emerges..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 516002 (2012)
Effect of Al Doping Concentration on Electronic and Optical Properties of CrSi2
Yan Wanjun, Zhou Shiyun, Xie Quan, Guo Benhua, Zhang Chunhong, and Zhang Zhongzheng
By using pseudo-potential plane-wave method of the first principle based on the density function theory, geometrical structure, electronic structure and optical properties of Al-doped CrSi2 are calculated and analyzed. The calculated results on geometrical structure and electronic structure show that the lattice constaBy using pseudo-potential plane-wave method of the first principle based on the density function theory, geometrical structure, electronic structure and optical properties of Al-doped CrSi2 are calculated and analyzed. The calculated results on geometrical structure and electronic structure show that the lattice constant a and b increase while c has little change, the volume of lattice expands, the band structure is still indirect and the Fermi energy moves into the valence band deeper and deeper with Al increase from 0 to 0.3333, the density of electronic states near the Fermi energy level is mainly composed of Cr-3d. Optical properties calculation indicates that after doping Al, static dielectric constant, the first peak of ε2(ω) and refractive index n0 increase, the average reflective effect decreases, the light absorption of CrSi2 effectively enhances, and then improves the photoelectric conversion efficiency after doping Al. These results offer theoretical guide for design and application of optoelectronic material of CrSi2..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 516003 (2012)
Medical Optics and Biotechnology
Brain Functional Analysis of Photon-Stimulation Functional Magnetic Resonance Imaging Based on Small-World Networks
Ding Shangwen, Qian Zhiyu, Li Weitao, Tao Ling, and Hu Guangxia
Differences of information transmission network hub, network aggregation and minimum path of information transmission under the states of photon stimulation and resting are studied. The brain functional network is constructed based on the small-world network theory. By analyzing the network connectivity of brain functiDifferences of information transmission network hub, network aggregation and minimum path of information transmission under the states of photon stimulation and resting are studied. The brain functional network is constructed based on the small-world network theory. By analyzing the network connectivity of brain function, cluster coefficient and the minimum path, the conclusion is drawn that stronger functional areas of information transferring are the insula and the posterior cingulate state. Thalamus and hippocampus have a greater aggregation. The information amount of photon stimulation from superior frontal gyrus to the middle occipital gyrus is passed through middle temporal gyrus under the photon stimulation. Those are drawn under rest state that stronger functional areas of information transferring are the cuneus and the lingual gyrus, the central lobule and superior temporal gyrus have a greater aggregation; the information amount of photon stimulation from left superior frontal gyrus to left the middle occipital gyrus is passed through middle temporal gyrus, cuneus and that from right superior frontal gyrus to right the middle occipital gyrus is passed through anterior cingulate gyrus and inferior occipital gyrus..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 517001 (2012)
Method of Sliding Focus Photoacoustic Microscopic
Liu Yanyan, Yang Xiaoquan, and Luo Qingming
Absorbers locating in the area of finite focal depth can be imaged with high resolution and signal-to-noise-ratio (SNR) using high resolution photoacoustic microscopy, whereas contours of actual biological tissues turn out to be irregular, causing non-uniform resolution and SNR in photoacoustic images. Sliding focus meAbsorbers locating in the area of finite focal depth can be imaged with high resolution and signal-to-noise-ratio (SNR) using high resolution photoacoustic microscopy, whereas contours of actual biological tissues turn out to be irregular, causing non-uniform resolution and SNR in photoacoustic images. Sliding focus method based on sparse contour scanning is introduced, first scan contour sparsely based on fixed focus, manually choose contour locations, then obtain the full contour matrix using biharmonic interpolation, which is then transformed to sliding focus matrix, second scanning is done in the last, during which the focus location is adjusted before each scanning step to make sure the absorbers locate in the area of focal depth, thereby images with uniform resolution and SNR can be obtained. Phantom experiment and in vivo blood vessels imaging are conducted to prove the validity of the method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 517002 (2012)
Nonlinear Optics
Condition for Suppression of Small-Scale Self-Focusing of High-Power Laser Beams by Spectral Bandwidth
Deng Jianqin, Zhang Jin, Yang Hua, Fu Xiquan, and Wen Shuangchun
Broadband laser can be used to relax restriction of nonlinear effect and obviously improve output power of high-power solid laser systems, because of the spectral bandwidth of such kind of broadband laser can delay the onset of self-focusing. It is found that the degree of self-focusing suppression is closely related tBroadband laser can be used to relax restriction of nonlinear effect and obviously improve output power of high-power solid laser systems, because of the spectral bandwidth of such kind of broadband laser can delay the onset of self-focusing. It is found that the degree of self-focusing suppression is closely related to the ratio of bandwidth and pulse duration, in the same pulse duration the bigger bandwidth is, the more obvious restraint effect is, and in the same bandwidth the restraint effect of bandwidth will become weaker with increasing the pulse duration. In actual neodymium-glass laser amplifying system, limited bandwidth can propagate through the amplification system due to the limited gain bandwidth and the gain narrow, which indicates clearly that the pulse duration as short as picoseconds is needed in this kind of solid laser system to achieve restrained small-scale self-focusing effect, while for longer pulse such as tens of picoseconds even nanoseconds, such limited bandwidth almost cannot influence the evolution of self-focusing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 519001 (2012)
Optical Design and Fabrication
Design and Study of Achromatic Phase-Only Superresolving Pupil Filter
Zhu Huafeng, Xu Dan, Wang Xiumin, Yun Maojin, Nan Yujie, Wang Ning, Li Dailin, and Tian Yanjie
An achromatic phase-only superresolving pupil filter based on Bessel function is proposed and designed. The effect of the design parameters of the pupil filter on the superresolving figures of merit such as normalized compression ratio and Strehl ratio is discussed, respectively. Achromatic phase-only superresolving puAn achromatic phase-only superresolving pupil filter based on Bessel function is proposed and designed. The effect of the design parameters of the pupil filter on the superresolving figures of merit such as normalized compression ratio and Strehl ratio is discussed, respectively. Achromatic phase-only superresolving pupil filters with the materials of calcite crystal and optical quartz glass can realize achromatic superresolution in the ranges of 380~555 nm and 300~600 nm respectively with the normalized compression ratio of 0.83, and a relatively high Strehl ratio is also obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 522001 (2012)
Design of Compact Optical System in Panoramic Three-Dimensional Head Mounted Display
Lu Haiping, Liu Weiqi, Kang Yusi, Wei Zhonglun, Feng Rui, and Fu Hanyi
To meet the command of panoramic three-dimensional head mounted display that is wide field of view (FOV), high resolving power and compact, light-weight structure, an optical system of eyepieces is designed. The dispersion characteristics of binary optical element (BOE) is used to correct the chromatic aberration, and To meet the command of panoramic three-dimensional head mounted display that is wide field of view (FOV), high resolving power and compact, light-weight structure, an optical system of eyepieces is designed. The dispersion characteristics of binary optical element (BOE) is used to correct the chromatic aberration, and the aspheric surface is selected to correct the aberrations (spherical aberration,astigmatism, coma and distortion). The organic light-emitting diode (OLED) micro-displayer is used to achieve compact and light-weight structure. Furthermore, the field-of-view-stitching method is used to obtain wide field of view. Obtained optical system can offer the horizontal FOV of 120°, the vertical FOV of 60°. Moreover, resolving power is 43 pixel/(°), the modulaiton transfer function (MTF)is higher than 0.45 at the spatial frequency of 45 lp/mm across the entire visual field, and the maximum distortion is less than 0.2% . The optical system has perfect performance and can meet the domanial demands of virtual reality display..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 522002 (2012)
Optical Devices
Design of Star Charts Simulator for High-Precision Star Simulator
Sun Xiangyang, Zhang Guoyu, Duan Jie, Sun Gaofei, and Gao Yue
In order to meet the demands of calibration on the ground for optical navigation sensor with high precision, a method is given to design precise star charts simulator based on the characteristics of conventional technique by combined the OLED light source with fiber-optic light guide technology. The general structure oIn order to meet the demands of calibration on the ground for optical navigation sensor with high precision, a method is given to design precise star charts simulator based on the characteristics of conventional technique by combined the OLED light source with fiber-optic light guide technology. The general structure of star charts simulator is presented after the analysis of its design. The coupling efficiency between the OLED and fiber is improved by a rebuilding of the coupling structure between the optical fiber and the light source as well as the fiber holding plate. By optimizing the design of the self-focusing lens in coupling system and the detail design of filters in stellar magnitude simulation system, a precise control is achieved to 5~10 for the stars positional accuracy. It is found that the design for star charts simulator approaches the requirement for the calibration of precise optical navigation star sensor through the theoretical analysis and the measurements for the magnitude and the stars positional accuracy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 523001 (2012)
Application of Dual-Peak-Transmission Sodium FADOF in Solar Velocity Field Observation
Zou Zhaowei, Cheng Xuewu, Yang Yong, and Gong Wei
Faraday anomalous dispersion optical filter (FADOF) is a precision spectrometer with high spectral resolution and spectral stability. This article analyzes the method using dual-peak-transmission FADOF for solar Doppler observation, which develops FADOF transmission spectrum calculating software, and carries out the prFaraday anomalous dispersion optical filter (FADOF) is a precision spectrometer with high spectral resolution and spectral stability. This article analyzes the method using dual-peak-transmission FADOF for solar Doppler observation, which develops FADOF transmission spectrum calculating software, and carries out the prototype experiment of sodium atoms FADOF with bimodal type transmission spectrum. Experiment shows good agreement between experimental results and theoretical ones, and the parameters meet the requirement of solar Doppler observation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 523002 (2012)
Novel Resonant Micro-Opto-Electro-Mechanical Scanning Mirror and Lissajous Pattern Display
Yan Bin, Yuan Weizheng, Qiao Dayong, and Liu Yaobo
Based on the micro-opto-electro-mechanical systems (MOEMS) technology, a new resonant micro scanning mirror is designed and fabricated. It is actuated by electrostatic combs fingers. Base on the employed silicon-on-insulator (SOI) technology the residual stress during the process is used to create vertical offset in coBased on the micro-opto-electro-mechanical systems (MOEMS) technology, a new resonant micro scanning mirror is designed and fabricated. It is actuated by electrostatic combs fingers. Base on the employed silicon-on-insulator (SOI) technology the residual stress during the process is used to create vertical offset in comb structures, which is regard as starting electrode. In order to realize their electromechanical characterizations, an optical experimental equipment is established. The results show that the device has advantages such as simple fabrication process, low driving voltage, and large scanning angle. In addition, two one-dimensional micro scanning mirrors are reasonably combined to make many different Lissajous scanning patterns, which agree very well with Matlab simulations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 523003 (2012)
Stray Light Suppression Property of Baffle with Honeycombed Wall
Chen Xue, Sun Chuang, and Xia Xinlin
Stray light propagation in the baffle with honeycombed wall is divided into two levels, the scattering inside honeycomb structures and the transmission by the equivalent surface of inner wall. An anisotropic reflection model is established to predict the bidirectional reflectance distribution function (BRDF) data of thStray light propagation in the baffle with honeycombed wall is divided into two levels, the scattering inside honeycomb structures and the transmission by the equivalent surface of inner wall. An anisotropic reflection model is established to predict the bidirectional reflectance distribution function (BRDF) data of the surface. By simulating the stray light propagation with the Monte-Carlo method, the suppression property of the baffle and the effects of coating reflectivity and geometric parameter of honeycomb are investigated. The results show that the baffle with honeycombed wall has a good performance of stray light suppression, and lower reflectivity of coating can enhance the performance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 523004 (2012)
Step Refractive Index Combined Triangular-Section Prism Generating Non-Diffracting Linear Structured Beam
Wu Zhiwei
A novel optical element - step refractive index combined triangular-section prism generating non-diffracting linear structured beam with longer distance is proposed. This element is designed with gluing positive and negative isosceles triangular-section prisms. Its property is the same as single positive isosceles triaA novel optical element - step refractive index combined triangular-section prism generating non-diffracting linear structured beam with longer distance is proposed. This element is designed with gluing positive and negative isosceles triangular-section prisms. Its property is the same as single positive isosceles triangular-section prism for beam transformation, and its equivalent index of refraction is decided by the difference of refraction index of positive and negative isosceles triangular-section prisms. Therefore, we can get an equivalent index of refraction closer to 1 by combining positive and negative isosceles triangular-section prisms with the approximate index of refraction. And also the non-diffracting linear structured beam with longer distance can be obtained. The technical problem of difficulty in machining the small bottom corner is solved. The formation mechanism of the non-diffracting linear structured beam is analyzed by geometrical optics, and the relevant parameters are also calculated. The intensity distribution is simulated by diffraction and interference theory. The results show that when a plane wave illuminates on the novel optical element, a non-diffracting linear structured beam is formed in longer distance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 523005 (2012)
Spectral Characteristics of Fiber Bragg Gratings in Large-Mode-Area Double-Clad Fibers
Xu Tuanwei, Li Fang, and Liu Yuliang
Based on the analysis of large-mode-area (LMA) double-clad fiber′s mode properties and optical power distribution in the measurement setup, reflection and transmission spectra of LMA fiber gratings are numerically simulated by using coupled-wave theory and transfer-matrix approach. Theoretical results indicate that theBased on the analysis of large-mode-area (LMA) double-clad fiber′s mode properties and optical power distribution in the measurement setup, reflection and transmission spectra of LMA fiber gratings are numerically simulated by using coupled-wave theory and transfer-matrix approach. Theoretical results indicate that the spectral shape depends on the power distribution between modes, and the reflectivity of LMA fiber grating can be calculated from the transmission spectrum of the fundamental mode. LMA fiber grating with the reflectivity of more than 99.7% has been fabricated in 20/400 μm double-clad fiber by phase mask method, the reflection and transmission spectra under different conditions are measured, and the experimental results agree well with the theoretical analysis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 523006 (2012)
Physical Optics
Effect Factors of the Focal Shift in Spatial-Variant Polarized Vector Beams
Leng Mei, Yang Yanfang, He Ying, Liu Haigang, Chang Qiang, and Li Chunfang
The intensity distribution of focused spatial-variant polarized Bessel-Gauss vector beams is numerically simulated in the vicinity of the focal plane by using Richards-Wolf vectorial diffraction method. The existence of the focal shift in the negative direction of propagation is proved. The magnitude of the focal shiftThe intensity distribution of focused spatial-variant polarized Bessel-Gauss vector beams is numerically simulated in the vicinity of the focal plane by using Richards-Wolf vectorial diffraction method. The existence of the focal shift in the negative direction of propagation is proved. The magnitude of the focal shift is closely associated with the order number of beam, beam width, wavelength and local polarization. The polarized state can be changed by adjusting the phase delay angle of the liquid crystal variable retarder, which can be continuously varied from 0 to π. The controllability of the focal shift in real time aroused by the phase delay angle will have great potential applications in optical micro-manipulations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 526001 (2012)
Quantum Optics
Influence of Polarized Light in Non-Abelian Cavity Quantum Electrodynanics Model
Xie Liangwen, Wang Faqiang, Liang Ruisheng, Jin Wei, and Guo Jianjun
In non-Abelian cavity quantum electrodynamics (QED) model, by using field quadrature operators instead of typical boson ladder operators, the interaction properties between atoms and polarized light are investigated. The effects of the initial two-mode polarized light on atomic population reversion and squeezing properIn non-Abelian cavity quantum electrodynamics (QED) model, by using field quadrature operators instead of typical boson ladder operators, the interaction properties between atoms and polarized light are investigated. The effects of the initial two-mode polarized light on atomic population reversion and squeezing properties of polarized light are also examined. The results show that relative phase angle and ellipticity angle are both important to the evolution of the atomic population reversion, which will not be changed and goes to the initial value 0 for the right-handed circularly polarized light, but which will present periodic collapse-revival phenomenon for the left-handed circularly polarized light. Furthermore, the left-handed circularly polarized light can be periodically squeezed for the left-handed circularly polarized light, however, it could not appear continually for the right-handed circularly polarized light..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 527001 (2012)
Entropy Exchange and Entanglement in Intensity-Dependent Coupling J-C Model with Atomic Motion
Hu Yaohua
Considering a moving two-level atom coupling with a single-mode thermal light field through intensity-dependence, reduced entropy change and entropy exchange between the atom and the field is studied by using quantum reduced entropy, entanglement is measured by using concurrence, the effect of initial atomic state, theConsidering a moving two-level atom coupling with a single-mode thermal light field through intensity-dependence, reduced entropy change and entropy exchange between the atom and the field is studied by using quantum reduced entropy, entanglement is measured by using concurrence, the effect of initial atomic state, the mean photon number of thermal field and the field-mode structural parameter on entropy exchange and entanglement are investigated. The results show that reduced entropy change and entanglement exhibit periodic evolution. When initial parameters are suitable, the complete exchange between the atomic and field reduced entropy occurs, which means there is a form of anti-correlated behavior between field and atom. In addition, the increase of field-mode structural parameter weakens reduced entropy exchange, and shortens period of entropy exchange. Entanglement between atom and field decreases as the transition photon number increases..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 527002 (2012)
Remote Sensing and Sensors
Thermal Effect on Spectral-Line Shift of Spaceborne Imaging Spectrometer
Zhang Junqiang, Yan Changxiang, and Lin Chao
To study the thermal effect on spectral-line shift of spaceborne imaging spectrometer, the relation between spectral-line shift and rigid-body motion of the mirror is analyzed, and the theoretical model, which is verified and corrected by simulation and thermal-optical test, is established to describe the spectral-lineTo study the thermal effect on spectral-line shift of spaceborne imaging spectrometer, the relation between spectral-line shift and rigid-body motion of the mirror is analyzed, and the theoretical model, which is verified and corrected by simulation and thermal-optical test, is established to describe the spectral-line shift property. The mathematical model based on linear optics model is established to describe the relation between spectral-line shift and rigid-body motion of the mirror, and the Mont Carlo method is employed to do the verification. The finite element analysis (FEA) method is used to get the rigid-body motion of mirror under different thermal loads. Code V API functions are used, in Matlab environment, to calculate the variation of the spectral line caused by rigid-body motions, and the spectral-line shift property is studied at the same time. The spectral-line shift model is corrected and verified by thermal-optical test. The results show that spectral-line integral deviation without extension and compression under the temperature from 8 ℃ to 28 ℃. Spectral-line shift values obtained by the thermal optical test are well coincident with the ones calculated by theoretical model. The maximum deviation between theoretical analysis and thermal optical test is not exceeding 12%. The new spectral-line shift model, corrected by the test data, realizes a high precision spectral line shift forecasting. The relative error is less than 5% and the absolute accuracy is better than 0.2 pixel..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 528001 (2012)
Study on Spectral Calibration of a Novel Interferometric Spectrometer with Supper-Resolution Capability
Shi Hailiang, Fang Yonghua, Wu Jun, and Xiong Wei
In connection with the new spatial heterodyne spectroscopy (SHS), integrated grating diffraction and space interference, a study on the spectral calibration technology is done. From interference mechanism of SHS, the spectral calibration difference between SHS and traditional dispersive spectrometer is analyzed, study In connection with the new spatial heterodyne spectroscopy (SHS), integrated grating diffraction and space interference, a study on the spectral calibration technology is done. From interference mechanism of SHS, the spectral calibration difference between SHS and traditional dispersive spectrometer is analyzed, study on ILS, spectral resolution, bandwidth calibration principle and method of SHS is done, and spectral calibration method of tunable laser with integrating sphere is designed and calibration data processing algorithm according to hyper-spectral data features is explored. Finally, using the above method CO2 spatial heterodyne spectrometer is calibrated experimentally, and calibration accuracy is validated using magnesium lamp. The results show that spectral calibration method can meet the requirements of SHS spectral calibration, and are consistent with theoretical values of prototype..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 528002 (2012)
Demonstration of a Laboratory Fresnel Telescope Synthetic Aperture Imaging Ladar
Dai Enwen, Sun Jianfeng, Yan Aimin, Zhi Ya′nan, Zhou Yu, Wu Yapeng, and Liu Liren
A laboratory demonstration of Fresnel telescope synthetic aperture imaging ladar system is presented. The target is two-dimensional (2D) scanned by a beam that is combined by two concentric and coaxial quadratic wavefont laser beams with orthogonal polarization. The scattered signal light from the target is collected bA laboratory demonstration of Fresnel telescope synthetic aperture imaging ladar system is presented. The target is two-dimensional (2D) scanned by a beam that is combined by two concentric and coaxial quadratic wavefont laser beams with orthogonal polarization. The scattered signal light from the target is collected by a telescope and is split into two beams by a polarized beamsplitter. The two separated beams then pass through a half and quarter waveplate, respectively, and enter a 90 degree 2×4 optical hybrid. The four outputs of optical signals from optical hybrid are detected by two pairs of balanced detectors and then stored in computer using AD converters. The image of the target can be reconstructed from the data acquired by 2D scanning through data processing. A point image of 0.3 mm×0.3 mm and 2D Chinese character are reconstructed in experiments with high resolution and contrast. The expected speckles are also observed in the reconstructed image that commonly existed in coherent imaging. The experimental results prove the correctness of the concept of the Fresnel telescope synthetic aperture imaging ladar..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 528003 (2012)
A New Method Based on Multimodal Stationary Sequence Modeling for Radar HRRP Target Recognition under Small Training Set Conditions
Wang Penghui, Xia Shuangzhi, Pan Mian, Zhang Xuefeng, Du Lan, and Liu Hongwei
A new recognition method is developed to relax the heavy requirement of training sample size in the radar high resolution range profile (HRRP) target recognition. The statistical characteristics of HRRP′s frequency spectrum amplitude (FSA) are analyzed. Then a linear Gaussian mixture state space model (LGMSSM) is propoA new recognition method is developed to relax the heavy requirement of training sample size in the radar high resolution range profile (HRRP) target recognition. The statistical characteristics of HRRP′s frequency spectrum amplitude (FSA) are analyzed. Then a linear Gaussian mixture state space model (LGMSSM) is proposed to describe the stationarity and multimodality of the FSA. Afterwards, an expectation maximization (EM) algorithm is derived for model parameter estimation. Finally, experimental results based on measured data show that the proposed method can obtain satisfactory recognition accuracy and rejection performance even with a very few training samples..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 528004 (2012)
Spectroscopy
Preprocessing Methods of Near-Infrared Spectrum Based on NLMS Adaptive Filtering
Chen Cong, Lu Qipeng, and Peng Zhongqi
The normalized least mean square(NLMS) adaptive filtering method is introduced to get the preprocessing of near-infrared (NIR) spectrum in order to deduct the noise from Near-infrared spectrum. Fifty-one soil samples are served as the target and the application of NLMS adaptive filtering method in NIR spectrum preproceThe normalized least mean square(NLMS) adaptive filtering method is introduced to get the preprocessing of near-infrared (NIR) spectrum in order to deduct the noise from Near-infrared spectrum. Fifty-one soil samples are served as the target and the application of NLMS adaptive filtering method in NIR spectrum preprocessing is discussed. The result after denoising is related to the real organic content of soil samples, then constructing a model according to this. Experimental results show that the correlation coefficient of the prediction set is improved from 0.8284 to 0.9654, and the root mean square error of prediction (RMSEP) is reduced from 0.3385 to 0.1606 after denoising with NLMS adaptive filter. So NLMS adaptive filter has a good effect in denoising the NIR spectrum. And it is also very useful to make the final model more representative, stable and robust. NLMS adaptive filter provides a new method for near-infrared sprctrum preprocessment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 530001 (2012)
Thin Films
High-Efficiency Polymer Solar Cells without Optical Spacer
Yang Shaopeng, Zhao Yanxin, Han Lingjie, Yang Qiman, Han Li, and Fu Guangsheng
Orgnic polymer solar cells are fabricated with the poly ［N-9′-heptadecany 1-2,7-carbazole-alt-5, 5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)］ (PCDTBT) with lower bandgap than poly (3-hexylthiophene) (P3HT) parforming as electron donor material and (［6,6］-phenyl C70-butyric acid methyl ester) (PC70BM) instead of [6Orgnic polymer solar cells are fabricated with the poly ［N-9′-heptadecany 1-2,7-carbazole-alt-5, 5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)］ (PCDTBT) with lower bandgap than poly (3-hexylthiophene) (P3HT) parforming as electron donor material and (［6,6］-phenyl C70-butyric acid methyl ester) (PC70BM) instead of [6,6]-phenyl-C60-butyric acid methyl ester (PC60BM), which has wider spectra absoption capability as electron accepter. The power conversion efficiency (PCE) has enhanced to 5.65% by controlling the growth rate and the environment of active layer. Then the thickness of active layer film is optimized, the PCE is improved to 5.84% with the short-circuit current density of 14.2 mA/cm2. The results demonstrate that even without optical spacer the active layer can also have a higher absoption rate and PCE with the control of growth rate and the thickness of active layer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 531001 (2012)
Preparation and Properties of Vanadium Oxide-Carbon Nanotube Composite Films
Wen Yuejiang, Xu Xiangdong, He Qiong, Fan Taijun, Yang Shubing, Huang Long, Ao Tianhong, Ma Chunqian, and Jiang Yadong
Multi-walled carbon nanotubes (MWCNTs) are functionalized by hydrogen peroxide under UV, then they are used to prepare vanadium oxide-carbon nanotube composite films by Sol-Gel, and a new method is proposed to produce vanadium-oxide thermistor films. Compared with the single vanadium oxide films, the as-prepared composMulti-walled carbon nanotubes (MWCNTs) are functionalized by hydrogen peroxide under UV, then they are used to prepare vanadium oxide-carbon nanotube composite films by Sol-Gel, and a new method is proposed to produce vanadium-oxide thermistor films. Compared with the single vanadium oxide films, the as-prepared composite films possess lower square resistance and optical band gap, larger temperature coefficient of resistance and light absorbance, and higher carrier migration rate. Therefore, such composite films are more suitable to be applied in uncooled infrared detectors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 531002 (2012)
Fabrication of Modified Polydimethylsiloxane and Multimode Optical Waveguides
Feng Xianghua, Ji Jiarong, and Dou Wenhua
The modified polydimethylsiloxane (M-PDMS) is synthesized by adulterating cross-linking of polysiloxane (HPSO) and divinylbenzene (DVB) into polydimethylsiloxane (PDMS). M-PDMS refractive index contrast PDMS are changed by 1%~1.8%. PDMS and M-PDMS bulk samples have well transmittance and low propagation loss. These benThe modified polydimethylsiloxane (M-PDMS) is synthesized by adulterating cross-linking of polysiloxane (HPSO) and divinylbenzene (DVB) into polydimethylsiloxane (PDMS). M-PDMS refractive index contrast PDMS are changed by 1%~1.8%. PDMS and M-PDMS bulk samples have well transmittance and low propagation loss. These benefits realize high productivity and low-cost mass production of large core multimode optical waveguides for optical interconnection. M-PDMS and PDMS are used for the core layer and the cladding layer. Large core(50 μm×50 μm) multimode optical waveguides are fabricated by the soft molding and simple replication, the length of waveguides is more than 20 cm. The optical propagation loss of waveguides is 0.137 dB/cm measured by digital scattering method at 633 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 531003 (2012)
Vision, Color, and Visual Optics
Establishment and Evaluation of Color Appearance Datasets about Low-Glossiness Color Printing Atlas
Liang Jing, Liao Ningfang, Song Li, Dong Shuwen, Lian Yusheng, and Wu Xiaohui
The prediction of color appearance is the basic theory and technology in modern color science field. To evaluate the color appearance of low-glossiness color printing atlas Liyin offset paper color printing atlas is taken as the experimental samples. Then based on color science and visual psychophysics methods, datasetThe prediction of color appearance is the basic theory and technology in modern color science field. To evaluate the color appearance of low-glossiness color printing atlas Liyin offset paper color printing atlas is taken as the experimental samples. Then based on color science and visual psychophysics methods, datasets of the samples′ color appearance are established. The mathematical statistics methods, correlation coefficient R2 and coefficient of variation CV, are used to evaluate the visual prediction results of Y-M in this color atlas under three different light sources. The experiment shows that the results are very different between A and the other two kinds of light sources, D65 and TL84. All findings indicate that the assessment of lightness and hue is more accurate than chroma..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 533001 (2012)
X-Ray Optics
Ring Artifacts Correction of Computerized Tomography Image Based on Polar-Coordinate Transform
Zhang Guoqiang, Zhou Hu, He You, Liu Huiqiang, Wang Yudan, Xue Yanling, Xie Honglan, and Xiao Tiqiao
Ring artifacts in computerized tomography (CT) images are introduced by the nonuniform response of the detector elements and the instabities of light source, which greatly influence three-dimensional reconstruction and quantitative analysis. A correction algorithm based on polar-coordinate transform and Fourier transfoRing artifacts in computerized tomography (CT) images are introduced by the nonuniform response of the detector elements and the instabities of light source, which greatly influence three-dimensional reconstruction and quantitative analysis. A correction algorithm based on polar-coordinate transform and Fourier transform is proposed. Through polar coordinate transform, ring artifacts are transformed to line artifacts. Then, Fourier transform is applied to the line artifacts image. Furthermore, the frequency-domain filtering processing by a two-dimensional low-pass filter is taken. The corrected image is got by the inverse transform process of both Fourier and coordinates. Experiments are carried out by Matlab software, the result indicates that the proposed algorithm not only eliminates the ring artifacts effectively, but also keeps the image edges and increases the signal-to-noise ratio (SNR). In addition, the correction speed proves that it can be applied for batch processing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 5, 534001 (2012)
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