Contents
2014
Volume: 34 Issue 1
48 Article(s)
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Atmospheric Optics and Oceanic Optics
New Method of Aerosol Extinction Coefficient Measurement
Gong Chunwen, Li Xuebin, Li Jianyu, Cao Yanan, Zhu Wenyue, Xu Qingshan, and Wei Heli
A new method is proposed for measurement of aerosol extinction coefficient by taking advantage of the characteristic of light transmission through coated glass tubes. When a ray of light of a particular wavelength penetrates through a glass tube filled with aerosols at a certain angle, the optical path length will be gA new method is proposed for measurement of aerosol extinction coefficient by taking advantage of the characteristic of light transmission through coated glass tubes. When a ray of light of a particular wavelength penetrates through a glass tube filled with aerosols at a certain angle, the optical path length will be greatly increased due to multiple reflection of the light on the tube wall, and the amount of light diminished by aerosols can be measured by the sensors at both ends of the glass tube. The ratio calculation method is used to remove the effect of measurement errors caused by the light intensity fluctuation, uneven tube wall, molecular scattering, etc. during the photoelectric conversion. The sensitivity for measuring the extinction coefficients of aerosols is raised. Finally, this method is used to measure the extinction coefficients of aerosols in the wavelength of 550 nm. Compared with the results obtained with a visibility meter, the results obtained with this method are reasonable. In addition, based on simple principles, this method can be easily applied..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 101001 (2014)
Prediction for Wavefront Correction Effect of Discrete Deformable Mirror Based on Filter Function
Ma Xuemei, Han Kai, and Zhang Bin
The correction about distorted wavefront of discrete deformable mirror is simulated by using the influence function, and the simulated correction result is fitted by super-Gaussian filter function. Consequently, a quantitative relationship between the crosslinking value of deformable mirror and the smooth factor of supThe correction about distorted wavefront of discrete deformable mirror is simulated by using the influence function, and the simulated correction result is fitted by super-Gaussian filter function. Consequently, a quantitative relationship between the crosslinking value of deformable mirror and the smooth factor of super-Gaussian filter function is determined, and a prediction model for correction effect on distorted wavefront of discrete deformable mirror based on filter function is established and improved. The validity and adaptability of the prediction model are verified and analysed for annular beams with distorted wavefront. In practical applications, the prediction model can be used to predict the correction effect of deformable mirror for laser beams with different wavefronts conveniently and accurately as long as the driver spacing and crosslinking values of the discrete deformable mirror are given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 101002 (2014)
Detectors
Light Emission Propenties Generated by a Single Electrode Discharge
Li Xuechen, Zhao Huanhuan, Bao Wenting, and Chang Yuanyuan
A stable plasma is generated in argon by using a single needle discharge device. The characteristics of the discharge are investigated by optical methods. Results show that the plasma plume length increases with increasing the peak value of the applied voltage or gas pressure, decreases with increasing the air content.A stable plasma is generated in argon by using a single needle discharge device. The characteristics of the discharge are investigated by optical methods. Results show that the plasma plume length increases with increasing the peak value of the applied voltage or gas pressure, decreases with increasing the air content. Spatially resolved measurement of light emission is conducted on the plasma plume with photomultiplier tubes. It has been found that the discharge near the needle point has a different behavior with other part of the plasma plume. The discharge in the plasma head originates from a corona discharge which emits light strongly at the negative half cycle, its emission is too weak to be detected in the positive half cycle. The other part of the plasma plume originates from the propagation of luminous cluster (plasma bullet) in the positive half cycle, and every position of which is almost volley in the negative half cycle..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 104001 (2014)
Fiber Optics and Optical Communications
Performance Analysis of High Altitude Platform Optical Communication Links with Spatial Diversity
Wang Xiang, Zhao Shanghong, Zheng Guangwei, Li Yongjun, Chu Xingchun, Zhao Guhao, and Zhu Zihang
Because of the position instability and atmospheric turbulence are two of the major influences on high altitude platforms (HAPs) optical links, the method to improve the performance of HAPs optical links using spatial diversity is presented. The expressions of HAPs optical links bit error rates (BER) for multiple-inputBecause of the position instability and atmospheric turbulence are two of the major influences on high altitude platforms (HAPs) optical links, the method to improve the performance of HAPs optical links using spatial diversity is presented. The expressions of HAPs optical links bit error rates (BER) for multiple-input multiple-output (MIMO) scheme and cooperative diversity scheme are obtained with on off keying (OOK) modulation system. And the optimum place for the relay platform is shown. The simulation results show that the improvement of cooperative diversity and optical MIMO on HAPs optical communications may be restricted by tracking error. The BER performance of MIMO optical links based on transmit laser selection is the best. Compared with MIMO optical links based on repetition coding, cooperative diversity is suited to optical communication links with bigger pointing error. The optimum place of the relay platform for HAPs optical links with cooperative diversity is independent on relay strategy and pointing error. The cooperative diversity scheme is superior to the HAPs MIMO optical links with repetition coding when the place of the relay platform is optimum..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 106001 (2014)
Fast Channel Allocation Method in Wireless Ultraviolet Network Based on Particle Swarm
Zhao Taifei, Li Qiong, Wang Yidan, and Zhang Aili
A fast channel allocation method in wireless ultraviolet network based on particle swarm is adopted aiming at the characteristic of non-line-of-sight and channel interference model. Fully considering the influence of conflict matrix caused by the space angle, a directional and fast channel allocation is designed. The rA fast channel allocation method in wireless ultraviolet network based on particle swarm is adopted aiming at the characteristic of non-line-of-sight and channel interference model. Fully considering the influence of conflict matrix caused by the space angle, a directional and fast channel allocation is designed. The relationship between average number of iterations, interference degree, convergence time and particle swarms number, channels are simulated and analyzed. Experimental results show that the channel allocation method of ultraviolet light network in this paper has the advantages of fast convergence speed and small degree of conflict. Meanwhile, it can ensure the quickness and accuracy of the channel allocation in wireless ultraviolet network..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 106002 (2014)
Fiber Optic Acoustic Vibration Sensor for the Monitoring of Water Sublimator
Zhao Peng, Liu Tiegen, Jiang Junfeng, Zhang Jingchuan, Liu Kun, Wang Shuang, Yin Jinde, Song Luyao, and Wu Fan
For the monitoring requirements of water sublimator, a fiber optic acoustic vibration sensor is developed based on the Fabry-Perot interference microcavity. The low temperature resistant polymer film material is used to make a ultra-thin diaphragm by stretching around as the sensitive components to detect acoustic vibrFor the monitoring requirements of water sublimator, a fiber optic acoustic vibration sensor is developed based on the Fabry-Perot interference microcavity. The low temperature resistant polymer film material is used to make a ultra-thin diaphragm by stretching around as the sensitive components to detect acoustic vibration information and reflecting surface of interference microcavity. The diaphragm is 1.2 μm in thickness. The sensitivity of system is 93 mV/Pa, and the linearity is up to 99.8%. A relatively flat frequency response is achieved from 1 kHz to 20 kHz. The monitoring experiment of water sublimator in the space environment simulator show that the sensor can survive in space environment where the temperature is below 77 K, and detect the real-time acoustic vibration signals generated by spewing ice when the water sublimator is going wrong..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 106003 (2014)
Fiber Sensor for Simultaneous Measurement of Temperature and Refraction Index Based on Multimode Fiber Core-Offset
Tong Zhengrong, Han Wei, and Cao Ye
A novel fiber interferometer sensor based on core-offset for simultaneously measuring refractive index and temperature is proposed. It makes a multimode fiber MMF2 left weld with a multimode fiber MMF1 which has a same core diameter and length in core-offset way, and right weld with a multimode fiber MMF3 which has a lA novel fiber interferometer sensor based on core-offset for simultaneously measuring refractive index and temperature is proposed. It makes a multimode fiber MMF2 left weld with a multimode fiber MMF1 which has a same core diameter and length in core-offset way, and right weld with a multimode fiber MMF3 which has a larger core diameter to be the sensor head. By observating the wavelength shifts of the interference dips, temperature and refraction index (RI) can be measured simultaneously since the core modes and the cladding modes have different sensitivities to the two parameters. The dips at 1536.98 nm and at 1545.24 nm are chosen to measure the temperature and the RI. Experiments indicate that the temperature sensitivities of the dips at 1536.98 nm and at 1545.24 nm are 0.105 nm/℃ and 0.052 nm/℃. The RI sensitivity coefficient of the dip at 1545.24 nm is 32.2 nm/RIU, whereas the dip at 1536.98 nm is insensitive. This fiber interferometer sensor can also be applied in other sensing fields and has good prospects..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 106004 (2014)
Design and Optimization of Multi-Core Fibers with Low Crosstalk and Large Effective Area
Yang Fang, Tang Ming, Li Borui, Fu Songnian, Liu Shuang, Wei Huifeng, Cheng Yu, Tong Weijun, and Liu Deming
Currently, optical communication network is developing rapidly towards large scale and large capacity. Higher request in optical fiber communication system is put forward to face with the huge pressure of transmission bandwidth. Under this background, multicore fiber (MCF) based on space division multiplexing (SDM), ovCurrently, optical communication network is developing rapidly towards large scale and large capacity. Higher request in optical fiber communication system is put forward to face with the huge pressure of transmission bandwidth. Under this background, multicore fiber (MCF) based on space division multiplexing (SDM), overcomes the congestion problem caused by the theoretical transmission limit of single mode fiber. Multicore fiber cannot be used in the transmission system only if it has the optical properties of low crosstalk and large effective area. Intensive simulation work based on beam propagation method (BPM) and finite element method are performed to find out key parameters which have a great influence on crosstalk and effective area in multicore fibers, which are used in the experiment to prove the correctness of simulated results. The designs of core pitch, the size and the refractive index of core and trench are optimized simultaneously to theoretically achieve optical properties suitable for the future large capacity transmission with low crosstalk less than -45 dB after 100 km and large effective areas larger than 130 μm2..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 106005 (2014)
Low-Loss Lens-Coupling Technique on Photonic Crystal Fibers
Zhang Lu
Based on the aligned lens transformation theory of Gaussian beam, a new lens-coupling method of photonic crystal fibers (PCFs) with low loss and high strength is put forward. Compared with the splicing method, this technique can eliminate the mode mismatch loss between two fibers, and is effective in connecting PCF witBased on the aligned lens transformation theory of Gaussian beam, a new lens-coupling method of photonic crystal fibers (PCFs) with low loss and high strength is put forward. Compared with the splicing method, this technique can eliminate the mode mismatch loss between two fibers, and is effective in connecting PCF with any other fibers, or connecting two fibers whose thermo-physical properties are so different that they cannot be spliced or jointed together. A PCF lens-coupling connection and test experimental platform is set up to achieve a 0.4 dB connection loss between endlessly single-mode PCF and G.652 fiber, and a 0.65 dB connection loss between polarization-maintaining PCF and G.652 fiber with good repeatability and high strength. Further error analyses, existed questions and improvements are given finally..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 106006 (2014)
Fourier Optics and Signal Processing
Study on Improved Hilbert-Huang Transform-Based Ultra-Narrow-Bandwidth Laser Gas Detection Noise Elimination
Jiang Shanchao, Cao Yuqiang, Sui Qingmei, Wang Jing, Wang Zhengfang, and Wang Ning
In order to reduce the effect of electric circuit and optical path noise on the trace gas detection and achieve the purpose that further improving the accuracy of trace gas detection system, ultra-narrow-bandwidth laser is utilized as the system light source, and harmonic detection and improved Hilbert-Huang transform In order to reduce the effect of electric circuit and optical path noise on the trace gas detection and achieve the purpose that further improving the accuracy of trace gas detection system, ultra-narrow-bandwidth laser is utilized as the system light source, and harmonic detection and improved Hilbert-Huang transform (IHHT) filtering algorithm are applied as the key algorithms of the data processing to construct the high precision trace gas detection system. Methane is used as the detect object, and theoretical calculation result shows that when the output center wavelength of the system light is 1650.959 nm, the correlation coefficient between methane gas volume concentration C and the first, second harmonic generation ratio of the output intensity I2f/If is 0.084639. The sensitivity experiment is carried out by inject specific fraction volume methane into the platform optical gas cell. The experimental data show that after the application of IHHT to reduce noise, the correlation coefficient between methane C and I2f/If is upgraded from 0.062585 which is obtained by applying fast Fourier transform (FFT) to process the data to 0.074884. The better effect of improved IHHT noise reduction depends on the less methane gas volume fraction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 107001 (2014)
Imaging Systems
Design and Analysis about Rapid Geometric Correction of Space Whiskbroom Time Delayed and Integration CCD Camera
Yang Fei, Jin Guang, Qu Hongsong, Yang Xiubin, Xu Kai, and Zhang Guixiang
High-resolution space-borne remote sensors usually adopt mobile imaging, combining pushbroom and whiskbroom modes. In these modes, to achieve fast and accurate splicing and imaging application, a mathematical modeling method is proposed to match optical image motion tracing. Through the analysis of impact of scan angleHigh-resolution space-borne remote sensors usually adopt mobile imaging, combining pushbroom and whiskbroom modes. In these modes, to achieve fast and accurate splicing and imaging application, a mathematical modeling method is proposed to match optical image motion tracing. Through the analysis of impact of scan angle and earth surface, the degrees of velocity mismatch and imaging deformation are computed and fast geometric correction is achieved by compensating the image shift for camera image plane at each point. Finally, physics time delayed and integration (TDI) CCD imaging simulation system is used for the simulation analysis of imaging. Simulation results show that the image shift amount increases and the image distortion turns serious with the increase of the scan angle. Velocity mismatch imaging is geometrically rapidly corrected under different scanning angles using optical tracing matching model. The mean square errors of simulation and experimental imaging quality are analyzed. The difference reaches to -0.000011 between simulation and experimental imaging and the mean square error of the corrected image turns small. The results show that this method can meet the demand of the ground satellite camera imaging simulation. The calibration method has high efficiency and is easy to splice..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 111001 (2014)
Investigation on Back-Modulation Long Distance Three-Dimensional Imaging Based on Compressed Sensing
Li Dong, Cang Ji, Xia Xinxing, Li Haifeng, Liu Xiangdong, and Liu Xu
Based on the theory of compressed sensing (CS), the method that the distant target object is illuminated by high power nanosecond pulsed laser and the target object is imaged by the telescope to digital micro-mirror device (DMD) plane is proposed. With the use of the loaded DMD patterns, the image of the target object Based on the theory of compressed sensing (CS), the method that the distant target object is illuminated by high power nanosecond pulsed laser and the target object is imaged by the telescope to digital micro-mirror device (DMD) plane is proposed. With the use of the loaded DMD patterns, the image of the target object is modulated (back-modulation), and a photomultiplier tube (PMT) as a single-pixel detector is applied to collect the total light modulated by the patterns, and the reconstruction of three-dimensional (3D) image of the distant target object is completed by the computation of compressed sensing. This system is applied to the imaging of the long-range 3D object. By the built of experimental system, the measurement of the absolute distances of the object at a distance of 230 m and 4.5 km is implemented and the 3D imaging of 64 pixel×64 pixel is realized. It is also demonstrated that for the image recovery of long distance using CS, with the increase of sampling rate, the quality and contrast of the recovered image are improved to some extent. The sparser the image of the object is, the less the number of required samplings for image reconstruction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 111002 (2014)
Sparse Angular Differential Phase-Contrast Computed Tomography Reconstruction Using L1-Norm and Curvelet Constraints
Li Mengjie, Li Jing, and Sun Yi
Differential phase contrast computed tomography (DPC-CT) is a novel X-ray inspection method which has obvious advantage in detecting weak absorption substance compared with conventional CT reconstruction methods. However, DPC-CT usually need to scan many times in order to obtain enough refraction angle information, whiDifferential phase contrast computed tomography (DPC-CT) is a novel X-ray inspection method which has obvious advantage in detecting weak absorption substance compared with conventional CT reconstruction methods. However, DPC-CT usually need to scan many times in order to obtain enough refraction angle information, which leads to unacceptably long exposure time and huge X-ray doses. Thus, the study of sparse angular DPC-CT reconstruction algorithm is particularly important. After analyzing the characteristics of the DPC-CT. Based on the theoretical framework of projection on convex set (POCS), a reconstruction algorithm for DPC-CT is proposed by combining L1 norm, curvelet coefficient constraint and dassical algebra reconstruction technique (ART). The numerical simulation and experimental results show that the proposed algorithm can significantly improve the image quality of the sparse angular DPC-CT reconstructions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 111003 (2014)
Analysis and Study on Detection Capability of Satellite Photoelectric Imaging System
Zhang Ying, Niu Yanxiong, Yang Lu, Niu Haisha, Xu Bing, Li Jiyang, Lü Jianming, Li Jianping, Liu Wenwen, and Zhang Chao
Satellite photoelectric imaging system can detect and recognize target at long distance. Maximum detection distance is its main property parameter. Based on the sun retro-reflection light of space target, several factors including sun light incidence angle, effective aperture of optics system, detector′s signal-to-noisSatellite photoelectric imaging system can detect and recognize target at long distance. Maximum detection distance is its main property parameter. Based on the sun retro-reflection light of space target, several factors including sun light incidence angle, effective aperture of optics system, detector′s signal-to-noise ratio (SNR) threshold and exposure time are analyzed to provide the mathematical model of the maximum detection distance. The results show that the limitation detection distance improves notly when the optics system effective aperture increases; the decrease in SNR threshold can improve the detection capability markedly and sun light incidence angle change has little influence when SNR threshold and sun light incidence angle vary simultaneously..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 111004 (2014)
Research on Principle and Experimentation of High-Resolution Optical Compressive Spectral Imaging
Chen Yuheng, Zhou Jiankang, Chen Xinhua, Ji Yiqun, and Shen Weimin
Optical compressive spectral imaging method is a novel spectral imaging technique that draws in the inspiration of compressed sensing, which has the features such as reducing acquisition data amount, realizing snapshot imaging for certain scenery, increasing signal to noise ratio and so on. Considering the influence ofOptical compressive spectral imaging method is a novel spectral imaging technique that draws in the inspiration of compressed sensing, which has the features such as reducing acquisition data amount, realizing snapshot imaging for certain scenery, increasing signal to noise ratio and so on. Considering the influence of the sampling quality on the ultimate imaging quality, matching the sampling interval with the modulation interval in the former reported imaging system, while the depressed sampling rate leads to the loss on the original spectral resolution. To overcome that technical defect, the demand for the matching between sampling interval and modulation interval is disposed and the spectral resolution of the designed experimental device increases more than threefold comparing with that of the previous method. Optimization method is improved and a variation term that represents the spectral-dimension continuousness of the data is added to the regularization function, which enhances the controllability and reliability for the data reconstruction. Result proves that the spectral channel number increases to a great extent effectively, the average spectral resolution reaches 1 nm, and the spectral images and curves are able to perform the spatial and spectral character of the target accurately..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 111005 (2014)
Instrumentation, Measurement and Metrology
Study on High Precision Ritchey-Common Test and Analysis of Test Distance Influence
Zhu Shuo, and Zhang Xiaohui
In order to realize high precision Ritchey-Common test for large flat mirrors, the relationship between the system pupil coordinate and test flat mirror surface coordinate is utilized to dispose the test wavefront, and then combine with the least square method to detach the alignment errors which are caused by the adjuIn order to realize high precision Ritchey-Common test for large flat mirrors, the relationship between the system pupil coordinate and test flat mirror surface coordinate is utilized to dispose the test wavefront, and then combine with the least square method to detach the alignment errors which are caused by the adjustments of optical system, after this an exact flat surface can be obtained. It analyzes the effects of the test distance on the relationship between the two coordinates and the value of Ritchey angle, and makes the test program according to analysis. In the test process, two measurements in different angles have been taken and the wavefront is found, after detaching the power errors, the peak-valley (PV) and root mean square (RMS) of the final results are 0.182λ and 0.0101λ, compared with the results of Zygo which are 0.229λ and 0.013λ for PV and RMS, the test accuracies of PV and RMS can reach λ/20 and λ/100, respectively. The experimental results prove that this method is effective to calculate the test flat surface and the theory of accuracy analysis is correct, it also realizes the high accuracy of Ritchey-Common test..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 112001 (2014)
Camera Pose Estimation Algorithm Based on Particle System Kinematics
Chen Peng, Hu Guangda, and Yan Guirong
Most pose estimation algorithms using a single two-dimensional (2D) image are designed based on totally or partially knowing the correspondence between three-dimensional (3D) and 2D feature points, but few have involved in a correspondenceless case. A camera pose estimation algorithm is proposed by using particle systeMost pose estimation algorithms using a single two-dimensional (2D) image are designed based on totally or partially knowing the correspondence between three-dimensional (3D) and 2D feature points, but few have involved in a correspondenceless case. A camera pose estimation algorithm is proposed by using particle system kinematics in classical mechanics. It can simultaneously decide the correspondence and the camera pose. Besides, by introducing object space collinear error and matching matrix, the proposed algorithm can be used not only in the case when the correspondences of 3D/2D feature points are one to one, but also in the case when the 3D feature points are partially occluded and when there are 2D false feature points in an image. Through experiments and comparison with other algorithms, the result shows that the proposed algorithm can effectively find the correct correspondence and estimate camera pose without increasing computational complexity, and the impact of image noises and 2D false feature points on the algorithm is little..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 112002 (2014)
Lasers and Laser Optics
Theoretical Modulation and Experiment on the Self-Reconstruction of Periodic Bottle Beam
Du Tuanjie, Wu Fengtie, Wang Tao, Li Pan, and Ouyang Yumei
The theories of diffraction integral and interference are used to analyze the whole process of self-reconstruction of periodic bottle beam which is generated by line-focusing the non-diffracting Bessel beam through an axicon. The intensity distributions along the propagation distance of the periodic bottle beam and theThe theories of diffraction integral and interference are used to analyze the whole process of self-reconstruction of periodic bottle beam which is generated by line-focusing the non-diffracting Bessel beam through an axicon. The intensity distributions along the propagation distance of the periodic bottle beam and the cross-section intensity distribution in different distance after the circle obstacle is simulated numerically; the minimum distance of self-reconstruction is calculated. The results of the proposed work show that after encountering obstacles, the periodic bottle beam will transport around obstructions, transmit along and restore the original characteristics after a distance transmission cycle bottle beam. Optical system is designed to prove the theoretical simulation, the cross-section intensity distribution around a circle or quadrate obstacle can be observed by a microscope and camera system and the experimental results agree well with the theoretical analysis. The results expand the application of the periodic bottle beam..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 114001 (2014)
Theoretical Study of the Threshold Power of Mode Instability in High-Power Fiber Amplifiers
Tao Rumao, Wang Xiaolin, Xiao Hu, Zhou Pu, and Liu Zejin
Mode instability refers to an abruptly mode change when the average output power increases above certain threshold power, which results in degrading of beam quality. Based on the mode-coupled model, the threshold power of onset mode instability, which is induced by quantum noise seeding or intensity noise seeding, is iMode instability refers to an abruptly mode change when the average output power increases above certain threshold power, which results in degrading of beam quality. Based on the mode-coupled model, the threshold power of onset mode instability, which is induced by quantum noise seeding or intensity noise seeding, is investigated and analyzed in detail. Analysis results show that the threshold power can be improved by 2~5 times for adopting tandem pumping technology and partially doping technology. Increasing the initial signal laser power, suppressing the intensity noise of the signal laser and reducing the power launched into the high order mode can also improve the threshold power. The investigation provides a reference to the design of high-power fiber laser systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 114002 (2014)
Power Limit of Different Single-Frequency Yb3+-Doped Fibers
Zhang Hanwei, Zhou Pu, Wang Xiaolin, and Xu Xiaojun
The characters of different Yb3+-doped fiber materials are integratedly studied and the single-frequency power limits of Yb3+-doped silica fiber, phosphate fiber, YAG crystal (or ceramic) fiber and sapphire fiber are carefully analyzed. The numerical result shows that the extractable power of YAG crystal (or ceramic) fThe characters of different Yb3+-doped fiber materials are integratedly studied and the single-frequency power limits of Yb3+-doped silica fiber, phosphate fiber, YAG crystal (or ceramic) fiber and sapphire fiber are carefully analyzed. The numerical result shows that the extractable power of YAG crystal (or ceramic) fiber and sapphire fiber can be more than 10 kW. The further study of the power limit shows that YAG crystal (or ceramic) fiber and sapphire fiber also have an advantage in single-mode working condition, indicating that these two kinds of fibers still have potentials to power scaling. For the fiber material of single-frequency fiber laser, the effective ways to boost the power limit are to reduce the stimulated Brillouin scattering (SBS) gain coefficient and improve the performance of heat conducting..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 114003 (2014)
Backward Focus Engineering with Controlled Cylindrical Vector Beams under Different Numerical Apertures
Liu Xuening, Wang Jiming, He Chongjun, and Liu Youwen
Based on the electro-magnetic radiation theory and the optical vector field integral theory, the relation between the property of optical vector focal fields and the numerical aperture has been studied. The electric and magnetic dipoles arrays are located along the optical axis in the focal volume. The radiation fieldsBased on the electro-magnetic radiation theory and the optical vector field integral theory, the relation between the property of optical vector focal fields and the numerical aperture has been studied. The electric and magnetic dipoles arrays are located along the optical axis in the focal volume. The radiation fields of them are collected and focused reversely. By manipulating and optimizing the dipole parameters and reversing the focused optical field with different numerical apertures, we study the rule of the optical needle and diffraction limited three-dimensional optical tube changing with the numerical aperture. The results show that the longitudinal polarization component purity, the edge slope and optical needle length decline with the decrease of numerical aperture and the full-width at half-maximum increases. The optical tube field is still azimuthally polarized with an intensity null at the center. The length of the intensity null along radial direction will increase. The research has significance on the application of focused vector beam under different numerical apertures..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 114004 (2014)
Machine Vision
Color Optical Microscopic Cell Image Segmentation Based on Color Difference Vector Field
Guan Tao, Zhou Dongxiang, and Liu Yunhui
Cell image segmentation is one of the hot topics in medical image processing. Most of the classical algorithms for cell image segmentation are based on grayscale images, which results in loss of color information in images. Based on analyzing the characteristics of the color cell images, we present a color difference vCell image segmentation is one of the hot topics in medical image processing. Most of the classical algorithms for cell image segmentation are based on grayscale images, which results in loss of color information in images. Based on analyzing the characteristics of the color cell images, we present a color difference vector field to model the color feature of cell images. In the color difference vector field, the difference between cell region and non-cell region is more distinct compared with other classical color spaces, such as HSV, YIQ and CIEL*a*b* spaces. Furthermore, this method is more robust for a large number of cell images. Based on the color difference vector field, a sequential match method is proposed for segmentation of cell images. In order to obtain more accurate results, the color difference strength is used to refine the segmentation results. Various color cell images containing overlapped cells have been tested to show the validity and effectiveness of the proposed method. The accuracy of the proposed method reaches 95.2%, which is higher than that of the RGVF Snake method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 115001 (2014)
Materials
2.7 μm Fluorescence and Energy Transfer Process in Er3+-Doped and Er3+/Pr3+ co-Doped Tellurite Glasses
Fan Xiaokang, Wang Xin, Li Xia, Li Kefeng, and Hu Lili
Er3+ singly doped and Er3+/Pr3+co-doped tellurite glasses 60TeO2-30WO3-10La2O3 are prepared by conventional melting method. The fluorescence spectra and lifetime of Er3+4I13/2 level pumped by 980 nm laser diode (LD) are investigated. The infrared and absorption spectra are measured. The absorption coefficient α is calcEr3+ singly doped and Er3+/Pr3+co-doped tellurite glasses 60TeO2-30WO3-10La2O3 are prepared by conventional melting method. The fluorescence spectra and lifetime of Er3+4I13/2 level pumped by 980 nm laser diode (LD) are investigated. The infrared and absorption spectra are measured. The absorption coefficient α is calculated based on the infrared spectrum. The spontaneous radiative coefficient Arad and fluorescence ratio β are acquired by Judd-Ofelt theory. Fuchtbauer-Laderburg theory is applied to calculate the stimulated emission cross section around 2.7 μm. The energy transfer processes and spectroscopic properties of Er3+-doping and Er3+/Pr3+ co-doping are analyzed under 980 nm LD excitation. The calculated absorption coefficient α of OH- is 0.57 cm-1, the spontaneous radiative coefficient Arad, fluorescence ratio β and the maximum stimulated emission cross section of Er3+4I11/2 to 4I13/2 transition are 60.6 s-1, 16.3%, and 1.13×10-20 cm2, respectively. The results indicate that this kind of tellurite glass is a promising matrix for 2.7 μm laser..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 116001 (2014)
Study on Synthesis and Luminescent Properties of a Novel Orange SrMoO4:Pr3+,B3+,Li+ Phosphor
Zhao Fen, Feng Wenlin, and Cheng Xueling
A novel orange SrMoO4:Pr3+, B3+, Li+ phosphor is prepared via the high-temperature solid state reaction process, and its structure, morphology and luminescence properties are studied. The X-ray diffraction (XRD) patterns show that a pure SrMoO4 crytal phase is obtained at 1200 ℃. The morphology of the sample under scanA novel orange SrMoO4:Pr3+, B3+, Li+ phosphor is prepared via the high-temperature solid state reaction process, and its structure, morphology and luminescence properties are studied. The X-ray diffraction (XRD) patterns show that a pure SrMoO4 crytal phase is obtained at 1200 ℃. The morphology of the sample under scanning electron microscope (SEM) has good dispersity and irregular shapes. The excitation spectra are made up of charge transfer band and characteristic transitions of 3H4→3P2,1,0 (448, 473, 487 nm, respectively) of Pr3+. The emission spectra of the SrMoO4:Pr3+, B3+, Li+ phosphors are characterized by peaks at 529(3P1→3H4,5), 545(3P0→3H5), 553(3P0→3H5), 600(1D2→3H4), 617(3P0→3H6), 645 nm (3P0→3F2). The strongest one appears at 645 nm. The intensity of excitation and emission peaks of SrMoO4:Pr3+ can be improved by doping B3+ and Li+. The optimum doping mole fractions are 0.15% B3+ and 0.35% Li+, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 116002 (2014)
Investigation on Optical Property and Negative Refractive Index in Double-Layer Chiral Structure of Optical Region
Liu Jinjing, Luo Xiaoyang, Liu Daoya, and Dong Jianfeng
A new four-fold symmetry double-layer chiral structure is designed, of which the operating wavelength band is in optical region. The transmission and reflection coefficients are obtained by numerical simulation, then the circular dichroism, polarization azimuth rotation angle, chiral parameter, refractive index of the A new four-fold symmetry double-layer chiral structure is designed, of which the operating wavelength band is in optical region. The transmission and reflection coefficients are obtained by numerical simulation, then the circular dichroism, polarization azimuth rotation angle, chiral parameter, refractive index of the structure are calculated. The results show that giant optical activity is found at the resonance wavelength region, and when the ellipticity is zero, the transmitted light becomes linearly polarized light completely, the polarization azimuth rotation angle reaches 55°. It is found that the negative indexes of the left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) waves can be realized without negative permittivity and permeability simultaneously. Most importantly, the negative index of the LCP can be achieved in wide band, which is not limited at resonance wavelength region. When the ellipticity is zero, the negative index also can be achieved. Taking into account the experimental manufacture, the substrate is added in the chiral structure. The simulated results demonstrate that resonance wavelength regions shift to long wavelength, and the polarization azimuth rotation angle still has 40° when the transmitted light becomes linearly polarized light completely..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 116003 (2014)
Medical Optics and Biotechnology
Effects of Scattering on Spectral Shape and Depth Resolution in Fourier Domain Optical Coherence Tomography
Guo Xin, Wang Xiangzhao, Bu Peng, Li Zhongliang, Nan Nan, and Huang Bingjie
The effects of scattering on interference spectral signal and depth resolution in Fourier domain optical coherence tomography are researched. The results obtained from theoretical analysis and simulation show that scattering of sample can change the measured spectral shape, which shifts to longer wavelength, and decreaThe effects of scattering on interference spectral signal and depth resolution in Fourier domain optical coherence tomography are researched. The results obtained from theoretical analysis and simulation show that scattering of sample can change the measured spectral shape, which shifts to longer wavelength, and decrease the depth resolution of image. When the value of scattering coefficient is larger and the position in sample is deeper, the spectral signal will shift more seriously and the depth resolution will decrease more. The depth resolution can be improved by using the corresponding correction function..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 117001 (2014)
Multicolor Fluorescence Detection in the Multiplex Quantitative PCR System and Spectra Crosstalk Correction Method
Zang Liuqin, Zhang Zhenxi, Miao Baogang, Peng Niancai, and Li Zheng
Optical design for multicolor fluorescence detection is the core part of multiplex quantitative polymerase chain reaction (PCR) system. According to the system requirements for excitation uniform, detection time and sensitivity, an optical system is presented, which is based on magneto-optical switch and photomultiplieOptical design for multicolor fluorescence detection is the core part of multiplex quantitative polymerase chain reaction (PCR) system. According to the system requirements for excitation uniform, detection time and sensitivity, an optical system is presented, which is based on magneto-optical switch and photomultiplier tube (PMT) detector. Four LEDs excitation unit and PMT detection unit are adopted to improve system sensitivity. Electronic optical switch combined with the one-dimensional scanning mechanism and filter to implement four-color fluorescence scanning on a 96-well standard PCR plate. The design avoids the crosstalk among the four color optical paths. Whereas the crosstalk generated by the spectral characteristics of the fluorescent dye itself can be estimated by standard iterative four-dimensional clustering analysis algorithm. We finally evaluate the systematical fluorescent spectra crosstalk by the experimental study of four commonly used dyes..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 117002 (2014)
Optical Design and Fabrication
Large Optical Surface Error Figuring by Ion Beam
Ma Zhanlong, and Sui Yongxin
In order to gain ultra-precision optical elements and to verify the machining capability of ion beam figuring (IBF), the figuring of large optical surface error by ion beam is investigated. Different scale removal functions are gained by changing different ion diaphragms. An 101 mm fused silica flat optical element wiIn order to gain ultra-precision optical elements and to verify the machining capability of ion beam figuring (IBF), the figuring of large optical surface error by ion beam is investigated. Different scale removal functions are gained by changing different ion diaphragms. An 101 mm fused silica flat optical element with initial surface figure peak-valles (PV) value of 417.554 nm and root mean square (RMS) value of 104.743 nm is figured by this mean. Through twelve iterations of 10, 5, 2 mm diameter ion diaphragms, an ultra-precision optical surface with PV value of 10.843 nm and RMS value of 0.872 nm is gained. The result shows that the large optical surface error can be figured by IBF, and the efficiency and precision can also be improved by larger and smaller ion diaphragms..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 122001 (2014)
Optical Devices
Beam Splitter with Two Fresnel Biprisms for Long Trace Profiler
Liao Jiasheng, Gong Yan, Zhang Wei, Li Jing, Li Chuncai, Yao Changcheng, and Min Lin
Beam splitter is one of the most important components in long trace profiler. A new beam splitter which is composed of two Fresnel biprisms is proposed. An incident beam is divided into two parallel exiting beams with a variable separation, equal-intensity and zero optical path difference. The characteristics of the FrBeam splitter is one of the most important components in long trace profiler. A new beam splitter which is composed of two Fresnel biprisms is proposed. An incident beam is divided into two parallel exiting beams with a variable separation, equal-intensity and zero optical path difference. The characteristics of the Fresnel biprisms is described in detail. The amplitude pattern and intensity pattern of interference fringes made by two exiting beams in detector is analyzed and simulated. The result of analysis and simulation suggests that the Fresnel biprisms not only owns the same function of four existing equal amplitude-splitting beam splitters but also can obtain high accuracy. We comparing the performance of the Fresnel biprisms with four existing equal amplitude-splitting beam splitters, and the result states that the Fresnel biprisms simultaneously own many merits including simple structure, zero optical path difference and variable separation with the exiting beams and so on. It can be a substitute for the existing amplitude-splitting beam splitters..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 123001 (2014)
Optical Properties of Cross-Shaped Array Optical Absorber in the Infrared Region
Li Yongqian, Su Lei, Wang Binbin, Guo Yongjun, and Shou Chen
Metamaterials have many exotic optical properties due to the interaction between the electromagnetic wave and the nanostructures. Metamaterials (PAMs) with metal-dielectric-metal structure have perfect absorption characteristics. The optical parameters of a cross-shaped absorber in infrared band are retrieved by the S-Metamaterials have many exotic optical properties due to the interaction between the electromagnetic wave and the nanostructures. Metamaterials (PAMs) with metal-dielectric-metal structure have perfect absorption characteristics. The optical parameters of a cross-shaped absorber in infrared band are retrieved by the S-parameters method. The mechanism of resonant absorption and optical tunability are studied. The experiments and simulations results indicate that the size of cross-shaped absorber can tune its effective optical parameters and can effectively increase its absorptivity on the conditions that the effective impedance matches well to the incident medium, and the imaginary part of the effective refractive index approaches as great value as possible. The absorptivity of optimized cross-shaped absorber is greater than 95% and maximum absorption of 80% is experimentally obtained in infrared region. The resonance peaks of the absorption spectrum depends on the length of the cross arm and thickness of the dielectric materials, while the width of the cross arm plays a critical role to the maximum absorption value. The characteristics of perfect absorption and spectral tenability of corss-shaped absorber make it promising in many applications, including infrared detection, spectral imaging and so on..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 123002 (2014)
Type Selection of Transparent Plate for Microalgae Photo-Bioreactor Building Based on Light Transmissivity Analysis
Li Yongfu, and Meng Fanping
The photo-bioreactor equipped with artificial light (AL-PBR) is an important mean for realizing rapid proliferation of microalgae, and therefore meeting the demand of relevant industries. To guide the material selection of AL-PBR, this study improves the current method by comparing seven transparent plates. ConsideringThe photo-bioreactor equipped with artificial light (AL-PBR) is an important mean for realizing rapid proliferation of microalgae, and therefore meeting the demand of relevant industries. To guide the material selection of AL-PBR, this study improves the current method by comparing seven transparent plates. Considering the light ecology of microalgae under different light wave bands, the photosynthetically active radiation (400~700 nm), red light (630~700 nm), blue light (430~480 nm) and ultraviolet B (UV-B, 280~320 nm) are taken into account for analyzing materials′ transmission performance. The higher the average transmittance of the former three bands is, the better the materials are, while the UV-B band is not. Results illustrate that if taking sunshine as an external light source, polycarbonate plate from abroad or common glass plate is the ideal material, and the former is better; if using monochromatic LEDs or fluorescent lamps, polymethyl methacrylate plate is an optimal option..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 123003 (2014)
A Dimming Lighting Source Based on Cold and Warm White LEDs
Xu Daisheng, Chen Xiao, Zhu Xiang, and Zheng Lihua
Dimming lighting sources are the basic parts of intelligent illumination. Fully utilizing the controllable performance of light emitting diode (LED), the dimming dynamic lighting LEDs are made successfully by cold/warm white LEDs and two channels′ pulse width modulation (PWM). According to photometric and colorimetric Dimming lighting sources are the basic parts of intelligent illumination. Fully utilizing the controllable performance of light emitting diode (LED), the dimming dynamic lighting LEDs are made successfully by cold/warm white LEDs and two channels′ pulse width modulation (PWM). According to photometric and colorimetric quantities of the selected cold/warm white LEDs, and the needed mixed color lighting sources, calculation model of duty cycle which controls the outputs of them are established. The constraints of duty cycle with correlated color temperature (CCT) as an objective parameter are also analyzed. Experiments show that not only the up-and-down luminous flux is less than 2.5%, and the deviation of CCT is less than 10 K when CCT of the mixed color lighting sources are changed, but also the CCT keeps unchanged when the output luminous flux is altered. Meanwhile, the analytic process of actual parameter design of mixed color lighting sources is in accordance with the selected performance parameters of lighting soures, which shows that the method is direct and has good practicality..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 123004 (2014)
Quantum Optics
Performance Optimization for the Reconciliation of Gaussian Quantum Key Distribution
Guo Dabo, Zhang Yanhuang, and Wang Yunyan
For reconciliation of Gaussian quantum key distribution, optimal quantization intervals of continuous variables are searched to maximize the mutual information between Alice and Bob. Based on both sliced error correction (SEC) and multilevel coding/multistage decoding (MLC/MSD) protocols, low density parity check (LDPCFor reconciliation of Gaussian quantum key distribution, optimal quantization intervals of continuous variables are searched to maximize the mutual information between Alice and Bob. Based on both sliced error correction (SEC) and multilevel coding/multistage decoding (MLC/MSD) protocols, low density parity check (LDPC) is employed in each level of coding streams. A one-time multistage iterative information update formula for MSD algorithm is also derived. In the implementation, double cross-linked list is used to store sparse matrix H of LDPC. C language is also used to realize the whole reconciliation process. These greatly reduce space complexity and speed up reconciliation process. Simulation results show that the proposed algorithm can reconcile 2×105 continuous quantum variables reliably when signal-to-noise ratio of receiver is above 4.9 dB, with reconciliation efficiency of 91.71%. On a server with 2.4 GHz CPU and 32 G memory, the speed of the reconciliation reaches 7262 bit/s..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 127001 (2014)
Quantum Entanglement and Correlations between Two Qubits Induced by a Heat Bath
Zheng Xiaolan, and Zhang Bin
The evolutions of quantum entanglement and correlations between two qubits in a heat bath are comparatively studied. Numerical simulation results show that, although a heat bath can almost always induce the quantum entanglement and correlations between the qubits, their dynamical evolutions are not identical. During thThe evolutions of quantum entanglement and correlations between two qubits in a heat bath are comparatively studied. Numerical simulation results show that, although a heat bath can almost always induce the quantum entanglement and correlations between the qubits, their dynamical evolutions are not identical. During the interaction with the bath, the qubits get quantum entangled, and then the entanglement disappears gradually, and the qubits get quantum correlated beyond entanglement which can be maintained. In this sense, the quantum correlations are more robust against decoherence in comparison with quantum entanglement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 127002 (2014)
Remote Sensing and Sensors
2D Fourier-Transform Imaging Algorithm for Synthetic Aperture Imaging Ladars
Liu Liren
A 2D Fourier transform imaging algorithm for synthetic aperture imaging ladar (SAIL) is proposed. The collected data are first compensated with a conjugated quadratic phase and then imaged by 2D Fourier transform. Unified data collection equations for side-looking SAILs with chirped laser, down-looking SAILs with shiftA 2D Fourier transform imaging algorithm for synthetic aperture imaging ladar (SAIL) is proposed. The collected data are first compensated with a conjugated quadratic phase and then imaged by 2D Fourier transform. Unified data collection equations for side-looking SAILs with chirped laser, down-looking SAILs with shifting of quadratic wavefronts and with deflection of plane wavefronts are formulated. Functions and relative imaging resolutions of the algorithm for these SAILs with rectangular and circular apertures are described and analyzed in terms of continuous variables and functions. Then, the expression of the 2D discrete Fourier transform is given. The feature of the algorithm is that the collected data in the time domain are transformed into the frequency domain both in the travel direction and in its orthogonal direction to be directly imaged. The mathematical formulation of the travel-direction imaging resolution varying along the orthogonal direction is deduced..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 128001 (2014)
Evaluation of Land Surface Polarization Models Based on Airborne Advanced Atmosphere Multi-Angle Polarization Radiometer Measurements
Wang Han, Sun Xiaobing, Sun Bin, and Hong Jin
Three models of land surface polarized reflectance are evaluated using data obtained from newly developed advanced atmosphere multi-angle polarization radiometer (AMPR) and laboratory. The spectral and angular responses are analyzed. It is found that the spectral response is very little, and 85% of AMPR aerosol retrievThree models of land surface polarized reflectance are evaluated using data obtained from newly developed advanced atmosphere multi-angle polarization radiometer (AMPR) and laboratory. The spectral and angular responses are analyzed. It is found that the spectral response is very little, and 85% of AMPR aerosol retrievals support the result. For the data from laboratory, the changes of polarized reflectance of yellow brown soil and red sandy soil are just 2.43×10-6 and 1.47×10-6 as the wavelength changes 1 nm. Angular responses of all three models match the measured data well with less difference between the high vegetation coverage data and models. After fitted, the model developed by Nadal and Bréon (NB) agrees with the measurements best, and the difference is about 1/2 of the other two models. NB model can describe the surface polarization more exactly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 128002 (2014)
Calculation of Overlapping Pixels of Staggered Linear Array Detectors for Space Camera
Wang Yun, Sun Shengli, and Lin Changqing
The focal plane of wide-field space camera is always comprised of several staggered linear array detectors. In order to ensure the coverage area of the camera without gap, a calculation method of overlapping pixels for staggered linear array detectors is proposed. The earth imaging model of the camera is established byThe focal plane of wide-field space camera is always comprised of several staggered linear array detectors. In order to ensure the coverage area of the camera without gap, a calculation method of overlapping pixels for staggered linear array detectors is proposed. The earth imaging model of the camera is established by utilizing coordinate transformation, and the reason that leads to gaps is discussed. The relative image motion between the leading and trailing rows of detectors along the direction of the linear array is calculated, and the influences on relative image motion introduced by orbital displacement, attitude disturbance and terrain elevation are analyzed based on Monto-Carlo method. The minimum value of the relative image motion is the minimum overlapping pixels of the adjacent detectors, so the calculation model of overlapping pixels of the adjacent detectors is given. The method is used in the design of the focal plane of an infrared camera, and the overlapping pixels of the adjacent detectors are determined. The method is validated by the matching test results of the infrared remote sensing images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 128003 (2014)
Research on Image Smear and Distortion Compensation in Panoramic Aerial Camera
Chen Li, Liu Zhiming, Wang Longqi, Huang Pu, and Xiu Jihong
In panoramic aerial camera pendulum sweep imaging process, the dithery scanning mirror position caused by the incomplete isolation of airborne vibration environment, causes a shaking of the visual axis, which makes the image in the sweep direction produce distortion and smear. Aiming at the above problem, the geometricIn panoramic aerial camera pendulum sweep imaging process, the dithery scanning mirror position caused by the incomplete isolation of airborne vibration environment, causes a shaking of the visual axis, which makes the image in the sweep direction produce distortion and smear. Aiming at the above problem, the geometric model is established among flight speed, altitude, target level angle and pitching axis speed compensation, with which the causes of the disturbances of image distortion and the influence of compensation precision on image smear pitching axis degree are analyzed. Through the model establishment and parameter analysis, the pitching axis control system dynamics and steady-state performance and robustness requirements are obtained. Laboratory dynamic target generator and parallel light pipe model are used to simulate the relative movement between camera and objects so as to test the precision of the control system. The exterior image in the vibration surroundings is used to test the disturbance compensation performance of the control system. Experiment results show that the steady speed error of pitching axis control system is less than 0.005°/s, that almost completely suppresses the image smear phenomenon; the speed compensation residual error under 7 Hz disturbance signal is less than 0.1°/s, and the system can effectively compensate the disturbance caused by the image distortions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 128004 (2014)
Reviews
Progresses of X-Ray Imaging Methodology and Its Applications at Shanghai Synchrotron Radiation Facility
Xiao Tiqiao, Xie Honglan, Deng Biao, Du Guohao, and Chen Rongchang
The X-ray flux of Shanghai synchrotron radiation facility (SSRF), a world-class SR source of the third generation, is about 12 to 16 orders of magnitude higher than X-ray tube flux. SR imaging has properties of high spatial resolution, high contrast resolution and high time resolution. The SR imaging can obtain in-situThe X-ray flux of Shanghai synchrotron radiation facility (SSRF), a world-class SR source of the third generation, is about 12 to 16 orders of magnitude higher than X-ray tube flux. SR imaging has properties of high spatial resolution, high contrast resolution and high time resolution. The SR imaging can obtain in-situ, non-destruction, high-resolution, three-dimension and dynamic imaging of samples; moreover, the phase imaging technique can be utilized which can extend its applications to low-Z materials like soft tissue and polymer. Since SSRF was formally opened to users in 2009, it has made significant research results in the fields of biomedical, materials science, paleontology, pedology and so on. In order to further support users′ experiments, the SSRF X-ray imaging group has carried out systematic X-ray imaging methodology researches in quantitative imaging, tomography, fast tomography data processing and so on, which substantially increases the experimental efficiency and sample adaptability. The progress of X-ray imaging methodology and its applications at SSRF are introduced..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 100001 (2014)
Scattering
Investigation on Characteristics of Stimulated Raman Threshold in a Single Mode Fiber
Yang Yuanhong, Yang Wei, Jiang Ting, and Yang Mingwei
The power evolutions of forward and backward Raman Stokes wave versus input pump power in a single mode fiber (SMF) are theoretically analyzed and simulated, which demonstrates an obvious threshold characteristic. A novel definition for Raman threshold in a SMF is proposed. The input pump power corresponding to the maxThe power evolutions of forward and backward Raman Stokes wave versus input pump power in a single mode fiber (SMF) are theoretically analyzed and simulated, which demonstrates an obvious threshold characteristic. A novel definition for Raman threshold in a SMF is proposed. The input pump power corresponding to the maximum of the second-order derivation of the power evolution curve of Raman Stokes wave versus input pump power is defined as the Raman threshold. A practical measurement approach for Raman threshold in a SMF is also demonstrated based on the proposed Raman threshold definition. By simulating and fitting the dependence of Raman threshold on the fiber characteristic parameter, the theoretical threshold equations for the forward and backward Raman scattering in a SMF are obtained, respectively. An experimental setup is established to verify the proposed definition and measurement method. The threshold characteristics for the forward and backward Raman scattering in a SMF with a length of 24 km are studied by using a pulsed pump. The experimental results agree well with the theoretical predictions and verify the effectiveness of the proposed definition and measurement method. The experimental results also demonstrate that the threshold of backward Raman scattering is approximately 24.9% in average higher than that of forward case at different fiber characteristic parameters in a SMF, which is coincident with the theoretical value of 25.3% obtained by simulation. The forward stimulated Raman scattering is relatively easier to occur in a SMF..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 129001 (2014)
Nanoparticle Sizing by Image Processing with Dynamic Light Scattering
Wang Zhiyong, Cai Xiaoshu, Xu Chengze, and Liu Lili
Image processing for nanoparticle sizing with dynamic light scattering (DLS) technique is introduced. A CCD is used to capture the spatial distribution of the scattered light by nanoparticles under Brownian motion. The sizes of the nanoparticles can be determined with the post-processing of the recorded data by calculaImage processing for nanoparticle sizing with dynamic light scattering (DLS) technique is introduced. A CCD is used to capture the spatial distribution of the scattered light by nanoparticles under Brownian motion. The sizes of the nanoparticles can be determined with the post-processing of the recorded data by calculating the autocorrelation functions of the scattered light. Standard nanoparticles of four different sizes (27, 79, 482, 948 nm) are used in the experiments. Since the frame rate of CCD is far lower than the frequency of photomultiplier, 55% glycerol/water emulsion is employed as disperse medium here, therefore. The measurement deviation is dramatically reduced from 15.1% to 1.9% in 27 nm nanoparticles at frame rate of 8290 frame/s. Compared with conventional DLS, this technique is advantageous due to the compact and simple measurement system with short measurement time which is 1% of conventional DLS measurement time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 129002 (2014)
Spectroscopy
Real-Time Analysis of Blood in Vivo Injected with Nitroglycerin Using Raman Spectroscopy
Qin Zongding, Xu Xuetang, Zhang Zhizhi, Lin Manman, Yao Huilu, and Liu Junxian
Raman spectra of blood in arteries of nude mice injected with nitroglycerin is analyzed in real-time and noninvasively. The Raman spectrum of blood in artery is captured every 10 s. Analysis results show that the spectra of the blood mainly have these characteristic peaks: 1548, 1618, 1654 cm-1 (protein) and 1125 cm-1 Raman spectra of blood in arteries of nude mice injected with nitroglycerin is analyzed in real-time and noninvasively. The Raman spectrum of blood in artery is captured every 10 s. Analysis results show that the spectra of the blood mainly have these characteristic peaks: 1548, 1618, 1654 cm-1 (protein) and 1125 cm-1 (blood sugar). Raman spectral intensity decreases from 280 s to 730 s after the injection of nitroglycerin, which shows that the blood concentration becomes diluted. This may be due to the expansion of blood vessels. The characteristic peak intensities before and after nitroglycerin injection change as below: the 1548 cm-1 peak intensity decreases from 1965.42 to 1273.61, by 35.2%; the peak 1125 cm-1 intensity decreases from 411.59 to 223.79, by 46.63%. This means that the contents of protein and sugar in blood decrease, namely, hemoglobin in the blood of nude mice denatures, and blood sngar levels significantly decrease. The Raman spectrum analysis in real-time in vivo can provide new technologies and methods for the study of the metabolic mechanism of nitroglycerin..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 130001 (2014)
Mid-IR Ultra-Sensitive CO Detection Based on Pulsed Quartz Enhanced Photoacoustic Spectroscopy
Dong Lei, Ma Weiguang, Zhang Lei, Yin Wangbao, and Jia Suotang
An ultra-sensitive gas sensor for trace carbon monoxide (CO) detection is developed. The fundamental ro-vibrational absorption bands of CO from 2135 cm-1 to 2225 cm-1 is continuously measured using a 4.65 μm pulsed external-cavity quantum cascade laser and quartz enhanced photoacoustic spectroscopy. The water vapor, acAn ultra-sensitive gas sensor for trace carbon monoxide (CO) detection is developed. The fundamental ro-vibrational absorption bands of CO from 2135 cm-1 to 2225 cm-1 is continuously measured using a 4.65 μm pulsed external-cavity quantum cascade laser and quartz enhanced photoacoustic spectroscopy. The water vapor, acting as a catalyst for vibrational energy transfer, is added to the targeted analyte mixture to improve signal amplitude. A detection limit of 4.6×10-8 is obtained for 3-ms lock-in amplifier time constant at atmospheric pressure with a laser scan rate of 18 cm-1/s and a 50% duty cycle, which corresponds to a normalized equivalent absorption coefficient of 1.07×10-8 cm-1W/Hz..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 130002 (2014)
Continuous Field Measurements of Stable Isotopes in Atmospheric Water Vapor by FTIR Spectrometry
Wang Wei, Liu Wenqing, and Zhang Tianshu
Fourier transform infrared (FTIR) spectrometry can be used to measure broadband infrared spectra, and it can analyze various gases in the air simultaneously. A new method of measuring stable isotopes in atmospheric water vapor by open-path FTIR spectrometry is described. An open-path FTIR system is utilized to continuoFourier transform infrared (FTIR) spectrometry can be used to measure broadband infrared spectra, and it can analyze various gases in the air simultaneously. A new method of measuring stable isotopes in atmospheric water vapor by open-path FTIR spectrometry is described. An open-path FTIR system is utilized to continuously measure the stable isotopes of water vapor in ambient air in a field experiment, which is based on the analysis of collected mid-infrared spectrum. The deuterium isotope ratios δD are also obtained. The measurement error of this system is about 0.25% and 1.60% for H216O and HD16O respectively, and the measurement precision is about 1.32‰ for δD. A detailed analysis of five-day data is presented to explore the variation of H216O, HD16O and δD with time. Furthermore, Keeling plot method is employed to study the deuterium isotopic signature of evapotranspiration. The results of the field experiment show the ability of this proposed measuring method combined with the open-path FTIR system for long-term measurement of the stable isotopes in the air..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 130003 (2014)
Thin Films
Effects and Corrections of Incidence Light Cone on Transmission Characteristics of Narrowband Filter
Zhang Junqiang, Wang Xiaoyi, Zhang Xinjie, Yan Changxiang, and Zhang Bin
All-dielectric film narrowband filter is widely used in space-borne multispectral remote sensor owing to its excellent optical capability, manufacturability and environmental adaptability. But center wavelength shift, due to entrance light cone angle, affects its spectral selective power seriously. In order to study efAll-dielectric film narrowband filter is widely used in space-borne multispectral remote sensor owing to its excellent optical capability, manufacturability and environmental adaptability. But center wavelength shift, due to entrance light cone angle, affects its spectral selective power seriously. In order to study effects of incident light cone on transmission characteristics of narrowband filter, an informal dielectric film narrowband filter is designed and manufactured. Changes of transmission characteristics with oblique incidence of Gaussian beam of uneven illumination are analyzed. The count model of effective transmission with vertical incidence light cone is established and verified by spectral calibration. Results show that blue shift of central wavelength is the main influence of incidence light cone on transmission characteristics of all-dielectric film narrowband filter. Prediction accuracy of transmittance calculated by effective transmission model is better than 0.15% of central wavelength. Therefor, count model of effective transmission can be used to calculate the actual transmittance of film narrowband filter with oblique incidence of Gaussian beam, and spectral selective ability of narrowband filter will be improved when the reasonable film design data corrected by center wavelength shift is utilized during film coating. This provides a new technical approach to solve the problem of the wavelength shift of film narrowband filter with vertical incidence light cone..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 131001 (2014)
Design and Fabrication of Polarizing Beam Splitter in Adaptive Optics Laser Guide Star System
Fu Xiuhua, Mo Zhaoyan, Huang Jinlong, Mo Shuhui, and Wu Boqi
In order to meet the requirements of adaptive optics laser guide star system, the appropriate film material is selected base on film theory. The film system′s evaluation funciton which is associated with the electric field is established by using needle optimization algorithm. The film is optimized to meet the requiremIn order to meet the requirements of adaptive optics laser guide star system, the appropriate film material is selected base on film theory. The film system′s evaluation funciton which is associated with the electric field is established by using needle optimization algorithm. The film is optimized to meet the requirements and has a lower electric field intensity distribution. Electron beam heating evaporation and ion-assisted deposition system are adopted for film preparation. The polarizing beam splitter meets the requirements of polarization coupling splitting system, and passes the environmental testing, which has a high laser damage threshold..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 131002 (2014)
Numerical Analysis of Cone Angle Effect of Optical Thin Films Characteristics
Liu Huasong, Wang Lishuan, Liu Dandan, Jiang Chenghui, Jiang Yugang, Sun Peng, and Ji Yiqin
Model of non-parallel light incident multilayer is established. Expressions of film characteristics are given for the case that the incident light beam has a circular cone angle. Numerical experiments are done on the properties of three kinds of typical optical thin films such as multi-cavity filter, non-polarization bModel of non-parallel light incident multilayer is established. Expressions of film characteristics are given for the case that the incident light beam has a circular cone angle. Numerical experiments are done on the properties of three kinds of typical optical thin films such as multi-cavity filter, non-polarization beam splitter and non-polarization cutoff filter. The results show that as the cone angle of incident light increases, the center wavelength moves to short-wave for the multi-cavity filter, and the transmittance and pass band get worse. The transmittance and waviness increase for both of s and p polarization in non-polarization beam splitter. For non-polarization cutoff filter, the transmittance in pass band shows periodic oscillation, the waviness of s polarization is larger than that of p polarization. There is an increasing trend overall for waviness, in addition the gradient of the transition region is growing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 131003 (2014)
X-Ray Optics
Application of Confocal Micro X-Ray Fluorescence Technique Based on Polycapillary X-Ray Lens in Analyzing Medicine with Capsule
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The confocal micro X-ray fluorescence technology based on two polycapillary X-ray lenses is used to analyze the elements in the medicines with capsule non-destructively. In this technology, two confocal lenses form confocal volume, and only the X-rays from the confocal volume can be detected by the detector, which ensuThe confocal micro X-ray fluorescence technology based on two polycapillary X-ray lenses is used to analyze the elements in the medicines with capsule non-destructively. In this technology, two confocal lenses form confocal volume, and only the X-rays from the confocal volume can be detected by the detector, which ensures non-destructive and in-situ analysis of elements in the capsule shell and the medicine inside to identify their species. X-ray fluorescence spectral characteristics of four types of medicines with capsule are analyzed. The experimental results show that different medicines have different X-ray fluorescence spectra, and different spectra correspond to different elemental compositions, which could be used to identify medicines. The confocal micro X-ray fluorescence technology can be used in the non-destructive and in-situ analysis of the samples with capsule, and has potential applications in identifying the types and the authenticity of medicines with capsule..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 1, 134001 (2014)
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