Contents
2015
Volume: 35 Issue 5
52 Article(s)
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Atmospheric Optics and Oceanic Optics
Regions of Spreading of Laser Beams Propagating through Non-Kolmogorov Atmospheric Turbulence
Yang Ting, and Ji Xiaoling
When laser beams propagate through atmospheric turbulence, the beam spreading depends on two mechanisms, i.e., free-space diffraction and atmospheric turbulence. The influence of turbulence on the beam spreading relates with diffraction. The regions spreading of partially coherent Hermite-Gaussian (H-G) beams propagatiWhen laser beams propagate through atmospheric turbulence, the beam spreading depends on two mechanisms, i.e., free-space diffraction and atmospheric turbulence. The influence of turbulence on the beam spreading relates with diffraction. The regions spreading of partially coherent Hermite-Gaussian (H-G) beams propagating through non-Kolmogorov atmospheric turbulence are studied in detail. The propagation distance is divided into three regions, in which the beam spreading is dominated by free-space diffraction, free-space diffraction and atmospheric turbulence, and atmospheric turbulence, respectively. The influence of beam parameters and turbulence parameters on the three regions is studied, and the relation between the first region and the Rayleigh region is also examined. In addition, the physical explanations of the main results obtained are given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 501001 (2015)
Control Performance Analysis of a Double Overlap Adaptive Optics System
Luo Qi, and Li Xinyang
Optical systems like telescopes are constantly affected by atmospheric turbulence and internal aberration disturbance. Conventional adaptive optics systems (AOS) are proved to be an effective way to eliminate external aberrations caused by atmospheric turbulence, however, when internal aberrations with high amplitude eOptical systems like telescopes are constantly affected by atmospheric turbulence and internal aberration disturbance. Conventional adaptive optics systems (AOS) are proved to be an effective way to eliminate external aberrations caused by atmospheric turbulence, however, when internal aberrations with high amplitude emerge, the problem becomes complicated. The double overlap AOS structure presented exploits an independent inner channel AOS to correct internal aberration disturbance, and an outer channel AOS mainly external to atmospheric turbulence. Furthermore, the correction abilities of this structure and conventional AOS are analyzed and compared. In addition, their correction performances under the situation where two aforementioned type aberrations simultaneously exist are numerically simulated. Results show that reasonably designed operating conditions of double overlap AOS make the performance better than conventional AOS, especially when internal aberrations become relatively stronger..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 501002 (2015)
Light Propagation through Non-Kolmogorov-Type Atmospheric Turbulence and Its Effects on Optical Engineering
Rao Ruizhong, and Li Yujie
Light propagation through non-Kolmogorov atmospheric turbulence and its effects on optical engineering are focus of applied optics research. Discussion and comparison are carried out for the optical properties of real atmospheric turbulence and theoretical models of non-Kolmogorov turbulence. Recent research progress iLight propagation through non-Kolmogorov atmospheric turbulence and its effects on optical engineering are focus of applied optics research. Discussion and comparison are carried out for the optical properties of real atmospheric turbulence and theoretical models of non-Kolmogorov turbulence. Recent research progress in last five years is summarized and related problems are analyzed on general propagation effects, effects in anisotropic turbulence, propagation of special beams, partially coherent beams and beam arrays, and these effects on optical engineering. Suggestions are proposed for next step on the monitoring technology of atmospheric turbulence, numerical simulation of light propagation through non-Kolmogorov turbulence and experimental study in real atmosphere..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 501003 (2015)
High-Resolution Retinal Imaging System with Dual Deformable Mirrors
Xiao Fei, Dai Yun, Zhao Junlei, Zhao Haoxin, Zhou Hong, Fan Xinlong, Zhang Xiaojun, Hu Yiyun, and Zhang Yudong
How to effectively correct ocular aberrations which vary fast from person to person and improve the application scope of adaptive optics retinal imaging system is the biggest problem in clinical application. It is difficult for a single corrector to compensate both low order and high order ocular aberrations simultaneoHow to effectively correct ocular aberrations which vary fast from person to person and improve the application scope of adaptive optics retinal imaging system is the biggest problem in clinical application. It is difficult for a single corrector to compensate both low order and high order ocular aberrations simultaneously. Due to the correction requirements of high order aberrations, a 169-element discrete piezoelectric deformable mirror with 3 millimeters spacing is successfully developed. Combined with a large stroke bimorph mirror, a retinal imaging system with two deformable mirrors is developed. The system can compensate low order aberrations up to ±4.5 diopters of defocus and ±3 diopters of cylindrical. High order Zernike aberrations up to the 8th order can also be corrected by this system. Both imaging quality and application scope are significantly improved. Taking the size of low order aberrations as inclusion criteria, a little sample is tested by the human retinal imaging experiment, and near diffraction-limited retinal images are achieved. The system has a clear application scope, which is convenient for future clinical application..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 501004 (2015)
Study of Wind Load on Four Astronomical Enclosures Based on Numerical Wind Tunnel Experiments
Xu Jianghai, and Gong Xuefei
Based on the two-equation k-ε turbulence model and four typical astronomical enclosures for the 2.5 m optical telescope, the numerical wind tunnel simulation is conducted by the computational fluid dynamics software Fluent. With the environment of different wind directions and same wind velocity, the distributions of tBased on the two-equation k-ε turbulence model and four typical astronomical enclosures for the 2.5 m optical telescope, the numerical wind tunnel simulation is conducted by the computational fluid dynamics software Fluent. With the environment of different wind directions and same wind velocity, the distributions of the wind velocity and turbulence kinetic energy around the telescopes and the effects on astronomical observation when the enclosures are opened and pressure distributions on the enclosures when the enclosures are closed are obtained. The results show that when the enclosures are opened, the classical and calotte enclosures with better closure property have significant effects to prevent the telescopes from high-speed wind of different directions and cause low turbulence kinetic energy but high seeing around the telescopes, while the columnar and foldable enclosures with better openness make the wind velocity around the telescopes and the turbulence kinetic energy along the observation directions both much higher, but the seeing are both much lower. When the enclosures are closed, the surface pressure on the four enclosures all change from positive maximum to negative maximum and then approach zero along the wind direction. According to the analytical results, some applicable conditions and unfavorable factors of different astronomical enclosures are proposed, which provide a reference for the structural design of astronomical enclosures under different weather conditions in the future..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 501005 (2015)
Measurements of Near-Ground Aerosol Backscattering Coefficient Profile with Side-Scatter Technique
Shi Bo, Tao Zongming, Ma Xiaomin, Shan Huihui, Zhao Sugui, Liu Dong, and Xie Chenbo
Aerosol is the main part of atmospheric contamination PM2.5 and haze. Near-ground aerosol affects human living and production directly. Using side-scatter lidar system based on charge-coupled device (CCD) and the retrieval method, the acquired experimental data are processed and analyzed. The detection correctness of CAerosol is the main part of atmospheric contamination PM2.5 and haze. Near-ground aerosol affects human living and production directly. Using side-scatter lidar system based on charge-coupled device (CCD) and the retrieval method, the acquired experimental data are processed and analyzed. The detection correctness of CCD side-scatter lidar system is validated by comparing with backscattering lidar system. The characteristics of aerosol backscattering coefficient at an altitude within 3 km in April 2014 at Dongpu Island, western suburb of Hefei are analyzed as changing with time and altitude, aerosol backscattering coefficient is linear to mass concentration of PM2.5 when the weather is fine, and aerosol concentration is comparatively large near ground. The experimental results show that side-scatter lidar system based on CCD is an effective new method of exploring the aerosol concentration near ground..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 501006 (2015)
Detectors
Research of Infrared Detectability of Hypersonic Vehicle
Zhou Jinwei, Li Jicheng, Shi Zhiguang, Chen Xiaotian, and Lu Xiaowei
Taking hypersonic waverider for example, the infrared detectability of hypersonic object in rarefied atmosphere space is researched. Heat flux distribution of the stagnation point as well as radiation-equilibrium temperature is calculated under different flying conditions with engineering algorithms; then atmospheric tTaking hypersonic waverider for example, the infrared detectability of hypersonic object in rarefied atmosphere space is researched. Heat flux distribution of the stagnation point as well as radiation-equilibrium temperature is calculated under different flying conditions with engineering algorithms; then atmospheric transmittance is calculated by summation over small intervals. After considering both effects of radiation difference between object and background, and dispersion on detector′ s operating range, a new model for calculation operating range of infrared detedion system is built. By simulation, dispersion coefficient has varied with distance between object and detector; meanwhile, the higher the velocity of object is, the further the operating range is. When compared with long-wave spectrum, detector working at short-medium spectrum has better operating range. By field test, proposed algorithm has high accuracy when compared with existing models..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 504001 (2015)
Fiber Optics and Optical Communications
Multi-Core Shared Tree Based Multipoint to Multipoint Multicast in Multi-Domain Optical Networks
Qin Panke, Chen Xue, Wang Lei, and Wang Liqian
In order to solve the problems of the optimal domains sequence choice without considering, overhigh resources occupied ratio and the unappeasable requirements of real- time quality of service (QoS), which cannot be settled by the conventional multipoint to multipoint (MP2MP) routing and wavelength assignment (RWA) algoIn order to solve the problems of the optimal domains sequence choice without considering, overhigh resources occupied ratio and the unappeasable requirements of real- time quality of service (QoS), which cannot be settled by the conventional multipoint to multipoint (MP2MP) routing and wavelength assignment (RWA) algorithms in multi- domain optical networks, a kind of multi- core node shared tree RWA heuristic algorithm (MSTDC) is proposed. The calculation can be parallelized. The delay and minimal cost can be constrained for multi- domain optical networks. The multi- domain problem is transformed into single domain by the algorithm from constructing a virtual topology. So it can realize the accurate calculation of number and the hosted domains of the mininlized cores. The source and destination nodes are added in different shared trees with delay constrained algorithms according to specific QoS selection strategy， respectively. The performance of the algorithm is demonstrated in a multi- domain optical networks topology with fifty routing nodes uniformly distributed in nine domains, and the simulation results show that the wavelength occupied ratio descends 51.1%, the success ratio of the route ascends 24.8% and running time of the algorithm descends 64.6%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506001 (2015)
Experimental Research of Curvature Sensor Based on Tapered Photonic Crystal Fiber Mach-Zehnder Interferometer
Fu Xinghu, Xie Haiyang, Zhu Hongbin, Fu Guangwei, and Bi Weihong
A curvature sensor is proposed base on tapered photonic crystal fiber(TPCF) Mach-Zehnder interferometer. A section of PCF is tapered after splicing both end of it with single-mode fiber(SMF), then a SMF-TPCF-SMF structure with 20 mm length is fabricated. By controlling the arc discharge parameters, the air holes of theA curvature sensor is proposed base on tapered photonic crystal fiber(TPCF) Mach-Zehnder interferometer. A section of PCF is tapered after splicing both end of it with single-mode fiber(SMF), then a SMF-TPCF-SMF structure with 20 mm length is fabricated. By controlling the arc discharge parameters, the air holes of the PCF near the splicing area are collapsed completely. So it can motivate the cladding modes better. Moreover, the splicing and tapering length of PCF are determined to make the sensor produce high curvature sensitivity. The experimental results show that the transmission spectrum of sensor appears blue shift obviously with the curvature increasing, and the shift of the peaks near 1590 nm is -6.06 nm. The curvature sensitivity of this sensor is -5.39297 nm/m-1 in the range of 0~1.16 m-1 curvature, and this sensor also has good linearity. This curvature sensor has the advantages of simple structure, easy manufacturing, high sensitivity and immune to the temperature cross-sensitivity compared to other sensors, so it can be used for measuring curvature in bridges, buildings, roads and so on..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506002 (2015)
Simulation Research on Strategy for Wavelength Division Multiplexing-Based Compensating Photon Polarization in Optical Fibers
Wang Jian, Zhu Yong, Zhou Hua, Su Yang, and Zhang Zhiyong
A relation between deviation angle, caused by state of polarization (SOP) evolution, and quantum bit error rate (QBER) is presented. The distribution of deviation angle for single SOP traveling several distances compensated by one reference signal of different wavelengths and two reference signals of the same SOP is siA relation between deviation angle, caused by state of polarization (SOP) evolution, and quantum bit error rate (QBER) is presented. The distribution of deviation angle for single SOP traveling several distances compensated by one reference signal of different wavelengths and two reference signals of the same SOP is simulated. A strategy which compensates photon polarization by using two reference lights of non-orthogonal SOPs and tracking the middle SOP of them in the Poincaré sphere for quantum key distribution (QKD) system is presented and simulated to be feasible..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506003 (2015)
Decoupling Dual Measurement Sensor System of Temperature and Strain Based on Twin-Core Fiber Cascaded with Fiber Bragg Grating
Kang Zexin, Sun Jiang, Ma Lin, Qi Yanhui, and Jian Shuisheng
A novel all-fiber sensing configuration for decoupling measurement of temperature and strain based on the twin core fiber (TCF) with an in-line embedded fiber Bragg grating (FBG) is proposed. A series of TCF filters with different lengths are fabricated experimentally, and the relationship between the free spectral ranA novel all-fiber sensing configuration for decoupling measurement of temperature and strain based on the twin core fiber (TCF) with an in-line embedded fiber Bragg grating (FBG) is proposed. A series of TCF filters with different lengths are fabricated experimentally, and the relationship between the free spectral range (FSR) and the fiber length of these filters is measured and analyzed, which are in agreement with the theory. It is found during the experiment that the TCF and FBG have different spectral responses for the changing strain and temperature. Optical spectrum analyzer (OSA) is used to monitor the wavelength at the bottom of the TCF transmitted spectrum and the wavelength drift of the fiber grating transmitted spectrum. The sensor tested has favorable repeatability for the responses of strain and temperature, and has a lower wavelength error compared with the spectrometer used in experiment. Withing a spectrometer having a wavelength distinguishability of 0.01 nm, the proposed all-fiber sensor can reach a distinguishability of 4.3048 με for stress and 0.4562 °C for temperature..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506004 (2015)
Influence of Feeding Guide′s Straightness Errors of Grating Ruling Machine on Diffraction Wave-Front of Grating and Intensity of Stray Light
Huang Yuanshen, Huang Yunbai, Yang Haima, Li Baicheng, Su Yangqing, and Sheng Bin
A comprehensive analysis has been made for straightness errors of feeding guide of grating ruling machine, and some mathematical expressions have been deduced among the straightness errors, the diffraction wave- front and the intensity of stray light, and the distance from the measurement axis of interferometer to the A comprehensive analysis has been made for straightness errors of feeding guide of grating ruling machine, and some mathematical expressions have been deduced among the straightness errors, the diffraction wave- front and the intensity of stray light, and the distance from the measurement axis of interferometer to the beginning of lines has been defined as position arm. Some following conclusions have been made. Position arm can magnify the straightness errors of dividing guide. The diffraction wave-front and the intensity of straight light are mainly affected by the position arm and the straightness errors of feeding guide. If the position arm is 50 mm, the horizontal straightness errors must be less than 0.15″. However, if the position arm is 10 mm, the horizontal straightness errors must be less than 0.74″ . Compared with the straightness in the vertical direction, the requirement of the grating- ruling machine for the horizontal straightness of dividing guide is higher. The value of theoretical calculation coincides with the experimental results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506005 (2015)
Influence of Temperature on the Precision of Bidirectional TDM Based Fiber-Optic Time Transfer
Huang Huang, Wu Guiling, Hu Liang, and Chen Jianping
The relationship of bidirectional propagation time deviation of optical fiber link with the temperature, bidirectional time interval, wavelength difference, and fiber length is derived. The influence of temperature on the precision of bidirectional fiber- optic time transfer based on time division multiplexing (TDM) isThe relationship of bidirectional propagation time deviation of optical fiber link with the temperature, bidirectional time interval, wavelength difference, and fiber length is derived. The influence of temperature on the precision of bidirectional fiber- optic time transfer based on time division multiplexing (TDM) is analyzed theoretically. The results show that the stability of time deviation of bidirectional TDM fiber link is degraded with the increase of the amplitude of temperature change, bidirectional time interval, and fiber length. For typical ambient temperature change, the stability of time deviation of 3000 km TDM fiber link can be less than 1 ps/d when the bidirectional time interval is less than 100 ms. When temperature change and fiber length are same, the stability of time deviation of bidirectional TDM fiber link with a time interval of less than 100 ms is always less than that of wavelength division multiplexing (WDM) fiber link with a wavelength spacing of larger than 0.1 nm. Bidirectional TDM time transfer experiments are carried out in laboratory on different lengths of fiber. The results show that the fluctuation of average asymmetry of TDM time transfer system is less than 29 ps when the fiber length is changed from 2 m to 100 km, close to the noise floor of the adopted time interval counter. The measured stabilities of bidirectional TDM time transfer over 100 km fiber link are better than 30 ps/s and 20 ps/d, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506006 (2015)
Low Complexity Frequency Offset Estimation Algorithm Based on Amplitude Ratio
Feng Jie, Xiao Junxiong, Han Jilong, Li Wei, Hu Rong, Yang Qi, and Yu Shaohua
A low comlexity frequency offset estimation algorithm based on amplitude ratio is proposed due to the frequency offset between transmitter laser and local oscillator (LO) laser in coherent optical M- ary quadrature amplitude modulation (M-QAM) systems. The proposed algorithm utilizes the relationship between the maximuA low comlexity frequency offset estimation algorithm based on amplitude ratio is proposed due to the frequency offset between transmitter laser and local oscillator (LO) laser in coherent optical M- ary quadrature amplitude modulation (M-QAM) systems. The proposed algorithm utilizes the relationship between the maximum amplitude and the second largest amplitude of the signal spectrum to estimate the frequency offset accurately, which reduces the computational complexity greatly. A coherent optical 20-Gbaud 16-QAM transmission system with single polarization is simulated to investigate the performance of the proposed estimator with respect to gradient descent(GD) and chirp Z- transform(CZT).The simulation results show that the performance of proposed algorithm does not fluctuate with the distribution of signal frequency and can achieve the very close performance to CZT and GD with three iterations. However, the computational complexity is reduced by over 75% in comparision with algorithms based on CZT and GD with three iterations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506007 (2015)
Wavelength-Shift-Free Optical Regeneration on Satellite Using Cascading SOA with Two-Stage Offset Filter
Dong Yi, Zhao Shanghong, Li Yongjun, and Deng Boyu
Aiming at solving the problem of signal injury caused by multi- retransmission in distributed satellite optical network, a wavelength- shift- free regenerative scheme based on cascading semiconductor optical amplifier (SOA) with two- stage offset filter is presented. Making use of the characteristic of optical pulse afAiming at solving the problem of signal injury caused by multi- retransmission in distributed satellite optical network, a wavelength- shift- free regenerative scheme based on cascading semiconductor optical amplifier (SOA) with two- stage offset filter is presented. Making use of the characteristic of optical pulse after the SOA with different recovery times of carrier can lead to different spectral shifts. The scheme imposes a red- shifted and a blue- shifted filter on signals respectively after two cascading SOAs, which not only gives the two times regeneration for optical pulse, but also compensates the wavelength shift caused by each regeneration. The results show that the amplitude noise and power jitter can be suppressed effectively, and the Q factor of signals can be improved 8 dB at most..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 506008 (2015)
Imaging Systems
Design of Simultaneous Imaging Polarimetry with Double Separate Wollaston Prism
Liu Jing, Jin Weiqi, Wang Yahui, and Wang Xia
In order to realize polarization imaging of dynamic scene, a simultaneous imaging polarimetry with double separate Wollaston prism is designed. This system is a combination of division-of-amplitude and divisionof-aperture, which can achieve four polarization images simultaneously on two detectors synchronized by externIn order to realize polarization imaging of dynamic scene, a simultaneous imaging polarimetry with double separate Wollaston prism is designed. This system is a combination of division-of-amplitude and divisionof-aperture, which can achieve four polarization images simultaneously on two detectors synchronized by external trigger. The principle of the system is briefly illustrated, and the design of optical system, choice of core devices and opto-mechinal design are emphatic introduced. The polarization imaging experiments of system are analyzed. The experimental results show that system performance on polarization splitting is well, and the residual gray level of polarization extinction image is under 15 with four 8 bit detector; the maximum frame rate can reach 90 Hz with external trigger, and polarization image of dynamic scene is sampled at 25 Hz; the system can focus on any distance larger than the nearest image distance, and system resolution reaches 76.9 cyc/mrad..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 511001 (2015)
Fast Geometric Correction of Space Time Delayed and Integration CCD Camera Dynamic Imaging Based on Ray Tracing Point Matching
Yang Fei, Qu Hongsong, Jin Guang, and Zheng Liangliang
Based on the linear array of time delay integration (TDI) charge coupled device (CCD) imaging principle, geometric distortion is analyzed in the process of attitude maneuver while the flexible satellite dynamic imaging. Because of the curvature of the earth and the attitude maneuver factors , the mapping shape of spaceBased on the linear array of time delay integration (TDI) charge coupled device (CCD) imaging principle, geometric distortion is analyzed in the process of attitude maneuver while the flexible satellite dynamic imaging. Because of the curvature of the earth and the attitude maneuver factors , the mapping shape of space geometry on focal plane is constantly changing. Dynamic imaging mode of space imaging geometry relationship between mathematics analytic expression is deduced based on the ray tracing point matching algorithm. Then using small satellite attitude control system simulation platform to verify experimentally TDI CCD camera mobile imaging fast geometric correction algorithm. The attitude determine angle accuracy and attitude stability is better than that of 0.05° and 0.005°/s. Results show that when the maximum scan angle of satellite is 45°, the designed algorithm can solve the problem of dynamic imaging geometric distortion and improve the quality of imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 511002 (2015)
Restoration of Double Degraded Images in Large Frame CMOS Aerial Cameras
Wan Lei, Zhang Ye, Zhou Dabiao, and Jia Ping
Due to electronic rolling shutter, high-speed large frame complementary mental oxide semiconductor (CMOS) aerial cameras not only suffer from motion blur, but also lead to geometric distortion caused by rolling shutter effect. The conventional method which deals with these two degraded factors separately is very compliDue to electronic rolling shutter, high-speed large frame complementary mental oxide semiconductor (CMOS) aerial cameras not only suffer from motion blur, but also lead to geometric distortion caused by rolling shutter effect. The conventional method which deals with these two degraded factors separately is very complicated and has a high computational complexity. To address the problems of linear motion and rolling shutter distortion resulting from aerial forward flight, a close relationship is derived between them through analyzing respective mathematical model. Furthermore, a method is proposed to restore double degraded images based on parameter estimation of linear motion. Then an experiment is designed to simulate aerial forward flight in which a CMOS camera controlled by the linear displacement stage imaging at different speed. Experiment results indicate that rolling shutter effect has no influence on the parameter estimation of linear motion. And the Interframe Transform Fidelity of restored images can be improved to about 27 dB. The calculation speed is 3.5 times faster than restoring step by step when obtaining the same good results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 511003 (2015)
Back-Side Correlation Imaging with Digital Micro Mirror
Tang Wenzhe, Cao Zhengwen, Shi Jianhong, Zeng Guihua, and Fang Shuanghong
For conventional imaging methods, the camera lens facing the object is necessary. Because of obstacles, conventional imaging methods in many cases are not get the ideal image of the target object. But in correlation imaging, by setting an appropriate angle, the image is got without the camera lens lying in front of theFor conventional imaging methods, the camera lens facing the object is necessary. Because of obstacles, conventional imaging methods in many cases are not get the ideal image of the target object. But in correlation imaging, by setting an appropriate angle, the image is got without the camera lens lying in front of the target object with the diffusing on the obstacles. Under a digital micro- mirror device (DMD) modulation, the reference path is omitted. Also, DMD may also be used to implement the correlation imaging with ordinary light source, such as light emitting diode. It has broad prospects in engineering projects..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 511004 (2015)
Application of Optical Coherence Tomography in the Detection of the Mural
Yang Shanshan, Zhu Rui, Mi Lei, Cao Yihui, and Li Qingyun
Based on the Michelson interferometer, optical coherence tomography (OCT) is a fast, non-contact, coherent optical imaging technology. OCT can image the internal microstructure underneath the surface. Archaeological objects are valuable and thus require nondestructive testing techniques. OCT, as a non-destructive analyBased on the Michelson interferometer, optical coherence tomography (OCT) is a fast, non-contact, coherent optical imaging technology. OCT can image the internal microstructure underneath the surface. Archaeological objects are valuable and thus require nondestructive testing techniques. OCT, as a non-destructive analysis technique, is suitable for testing any part of the mural and other cultural relics. High resolution OCT images can provide the detailed information of the paint layer on the surface and the ground layer underneath the surface, which is elusive for traditional techniques. The technique of OCT is introduced and the verification experiment of the mural of Tang dynasty is carried out. From OCT images, defect information of the paint layer on the mural topside and structure underneath the surface can be seen. The information is of great help to the research and repair of the mural. OCT can be used in the research and repair of murals as a powerful tool for the researchers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 511005 (2015)
Instrumentation, Measurement and Metrology
Reflected Spot Center Offset Correction in Laser Triangulation Measurement
Zhou Xingmin, Liu Hengbiao, and Ge Jianmin
During the laser (single) triangulation measurement, the measurement error of the surface profile height is caused by the deflection of projecting beam axis or the reflected spot center offset of projecting beam shining on object surface with nonuniform reflectivity. A method is introduced to amend the deflection of prDuring the laser (single) triangulation measurement, the measurement error of the surface profile height is caused by the deflection of projecting beam axis or the reflected spot center offset of projecting beam shining on object surface with nonuniform reflectivity. A method is introduced to amend the deflection of projecting beam axis and the reflected spot center offset of projecting beam by using dual- triangulation light path, and a modifier formula is deduced. It is proved to be right through the profile height measurement on the reflectivity mutation position of the object surface. According to dual- triangulation measurement of the grayscale stripe template profile, the root mean square deviation of the profile height is less than 0.07 mm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 512001 (2015)
Refractive Index Measurement System of Liquid Based on Surface Plasmon Resonance
Chen Qianghua, Liu Jinghai, Luo Huifu, He Yongxi, Luo Jun, and Wang Feng
Refractive index is an important parameter who indicates the material information. In chemistry, biology, medicine and other fields, the samples are usually made of low concentration solutions for chemical or physical reactions, from which various properties and parameters of the samples are determinated by detecting sRefractive index is an important parameter who indicates the material information. In chemistry, biology, medicine and other fields, the samples are usually made of low concentration solutions for chemical or physical reactions, from which various properties and parameters of the samples are determinated by detecting small changes of the refractive index of the solutions. So that, a kind of laser measurement method for liquid refractive index is presented based on surface plasmon resonance (SPR) and phase detection. The theoretical analyses indicate that the phase difference change between p and s polarization components of the reflected light is almost linear with the fluctuation of the refractive index at the range of 1.333~1.336. Thus the measurement equation is derived. Corresponding refractive index measurement system is built based on a heterodyne interference optical path using a dual-frequency laser. The system has strong anti-interference ability because of the common light path and high precision because of using phase measurement. The experimental results of measuring glycerine solution refractive index are consistent with the theoretical analysis, and agree with the results of another method, where the error between each other is less than 2.0×10-5. The method can be widely applied in the fields of biological detection, chemical analysis, medical diagnosis, pollution research and so on..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 512002 (2015)
Analysis the Influence of Pyramidal Error on the Encoder Accuracy Test by Using Coordinate Transformation
Tian Liude, Liu Chaohui, Zhao Jianke, Duan Yaxuan, Pan Liang, Zhao Huaixue, Long Jiangbo, Zhou Yan, and Li Kun
In order to realize the high precision measurement of encoder accuracy, the principle and method to measure encoder accuracy by using polyhedron and autocollimator are introduced. The polyhedron coordinate system and autocollimator measurement coordinate system are established, and the precise mathematical model is estIn order to realize the high precision measurement of encoder accuracy, the principle and method to measure encoder accuracy by using polyhedron and autocollimator are introduced. The polyhedron coordinate system and autocollimator measurement coordinate system are established, and the precise mathematical model is established, which is relation with the measurement error of the encoder accuracy and pyramidal error. The simulation results show that the encoder shaft tilt angle and tilt direction will affect the measurement results of the encoder accuracy. Measurement error of encoder accuracy increases with encoder shaft tilt angle, and approximately proportional to the square. Measurement error of encoder accuracy changes with encoder shaft tilt direction. When encoder shaft tilt direction is 0°or 180°, measurement error is the smallest; When encoder shaft tilt direction is 90°or 270°, measurement error is the maximum. As encoder shaft tilt angle is 5′, the measurement errors can reach 0.11"~0.48", which cannot be ignored for encoder with 1~3 levels of precision grade. Pyramidal error should be cotrolled in the appropriate range based on the precision grade of measured encoder. Specific requirements on pyramidal error are given for encoders with different precision grades..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 512003 (2015)
Laser Heterodyne Interferometric Signal Processing Method with Compensation at Unstable Zero Phase Difference Based on Pulse Counting
Zhang Enzheng, Hao Qun, Yang Ye, and Zhou Yanjiang
A zero phase difference jumping compensation processing method for heterodyne interferometric signal processing based on pulse counting is proposed, which can guarantee the correction integration of measured integer and fraction phase. The integer phase measurement is realized by counting pulse numbers of two interfereA zero phase difference jumping compensation processing method for heterodyne interferometric signal processing based on pulse counting is proposed, which can guarantee the correction integration of measured integer and fraction phase. The integer phase measurement is realized by counting pulse numbers of two interference signals and synchronously subtracting. The fraction phase measurement is realized by frequency mixing and frequency reduction to improve the measurement resolution. A dynamic base signal is generated by tracking the reference interference signal with phase-locked loop and the signal is used for frequency mixing to solve the problem of frequency changing of heterodyne interference signals. This method can improve the resolution stability of fraction phase measurement. The verification experiments are done with a function generator，including phase measurement precision, integer counting and fraction phase measurement. A two-pass heterodyne interferometric optical layout is constructed for displacement measurement experiments, the displacements of precision stages are measured to verify the effectiveness of the proposed compensation method for integration of integer and fraction and the feasibility of the implemented signal processing method in actual heterodyne interferometric displacement measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 512004 (2015)
Research and Uncertainty Analysis of Probe Based on Non-Diffracting Beam for Measuring Coordinates
Ma Guolu, and Zeng Guoying
The probe technique based on non-diffracting beam is proposed to be combined with a total station or a laser tracker to form a combined measuring system, which realizes the coordinate measurement of hidden parts in large spaces, in large-span measurement environments, space barrier, blocking.Depression of the measured The probe technique based on non-diffracting beam is proposed to be combined with a total station or a laser tracker to form a combined measuring system, which realizes the coordinate measurement of hidden parts in large spaces, in large-span measurement environments, space barrier, blocking.Depression of the measured point and other factors make it impossible to optically and directly measure some areas of the measured article. A attitude measurement probe prototype based on non-diffracting beam technology is developed for a system combined with a total station applied in coordinates precision measurement of hidden areas in large-scale space, the uncertainty of spatial location measurement is analyzed, and the measurement comparison experiment is completed. Experimental results and analysis indicate that the precision of probe’s attitude-measuring system and combing measurement system are 1 mrad and ± 1 mm, respectively, demonstrating more flexibility and reliable precision during combined measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 512005 (2015)
A Novel Spatial Filtering Velocimeter Based on Linear CMOS-Type Spatiotemporal Filter
He Xin, Long Xingwu, Zhou Jian, and Nie Xiaoming
In order to eliminate directional ambiguity and to reduce standard uncertainty in velocity measurement, a novel spatial filtering velocimeter based on a spatiotemporal filter is established. The spatiotemporal filter is structured by a high speed complementary metal oxide semiconductors (CMOS) linear image sensor. The In order to eliminate directional ambiguity and to reduce standard uncertainty in velocity measurement, a novel spatial filtering velocimeter based on a spatiotemporal filter is established. The spatiotemporal filter is structured by a high speed complementary metal oxide semiconductors (CMOS) linear image sensor. The spatial filtering characteristic of the filter is analyzed theoretically. The power spectrum of the output signal is obtained by fast Fourier transform (FFT), and is corrected by a frequency spectrum correction algorithm, named energy centrobaric correction. Therefore, the standard uncertainty of frequency measurement is reduced. This novel velocimeter is used to measure the moving velocity of a conveyor belt. The experiment verifies the feasibility of the spatiotemporal filter for directional discrimination. Furthermore, the relative standard uncertainty of velocity measurement is analyzed experimentally. Experimental results of the presented spatial filtering velocimeter using spatiotemporal filter show that the relative standard uncertainty of velocity measurement is much reduced compared with that of frequency measurement. The reduced relative standard uncertainty of velocity measurement is below 0.24% , which can be further reduced by adjusting the parameters of the spatiotemporal filter..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 512006 (2015)
Integrated Optics
Ultra-Compact Optical Filter with Rectangular Ring Resonator and Mach-Zehnder Interferometer
Wang Shuang, and Liu Ke
Optical filter based on microring resonator usually has drawbacks such as narrow bandwidth and larger radius of curvature. An ultra-compact optical filter consisting of rectangular ring resonator incorporated with two Mach-Zehnder interferometers is proposed and optimized, and the device is formed by trench-based nanopOptical filter based on microring resonator usually has drawbacks such as narrow bandwidth and larger radius of curvature. An ultra-compact optical filter consisting of rectangular ring resonator incorporated with two Mach-Zehnder interferometers is proposed and optimized, and the device is formed by trench-based nanophotonic frustrated total internal reflection couplers and total internal reflection mirror-based 90o bends waveguide. The performances such as transfer function, quality factor, and transmission characteristic are analyzed by using statespace representation and finite difference time domain (FDTD) methods. The dependence of filtering features on both different coupling coefficients and loss coefficients is calculated with state-space representation method. The FDTD simulation results show the device exhibits an asymmetric wavelength interleaver filtering effect with the different ratios of pass-band and stop-band bandwidths when the coupler reflection coefficient is close to the coupler transmission coefficient. The quality factor of about 3120 and the free spectral range up to 50.6 nm are observed in such small 25 μm ×8 μm chip area when the coupler reflection coefficient is far larger than the coupler transmission coefficient. The compact configuration of device layout is beneficial to the extension at two-dimensional directions for highly dense photonic integrated circuits..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 513001 (2015)
Lasers and Laser Optics
Effect of Structural Parameters of Deformable Mirrors on Phase Characteristics of High-Power Laser
Peng Jiaqi, Hu Xiaochuan, Chen Lixia, and Zhang Bin
The thermal distortion of the deformable mirror (DM) arised from the high-power continuous laser beam brings about the phase distortion and further degrades the beam quality. The model for the DM is built up using the finite element analysis software ANSYS. The characteristics of the thermal distortion of the DM and thThe thermal distortion of the deformable mirror (DM) arised from the high-power continuous laser beam brings about the phase distortion and further degrades the beam quality. The model for the DM is built up using the finite element analysis software ANSYS. The characteristics of the thermal distortion of the DM and the reflective mirror are analyzed and compared. The influence of structural parameters of the DM on the incident light phase are also discussed. The results indicate that, the thermal distortion of the DM is more obvious compared with the high reflective mirror. The high frequency phase distortion introduced by thermal distortion increases with the decreasing of the spacing of heads. The length of heads exhibits a significant influence on the high frequency components and the high frequency phase distortion increases with the decreasing of the length of heads. As a result, high frequency phase distortion introduced by the thermal distortion can be diminished through increasing the length of heads appropriately. The proportion of the high frequency phase distortion decreases with the increasing of the diameter of heads, leading to the decreasing of correction capability. Consequently, the diameter of heads should be considered comprehensively in the practical application. The results obtained can provide valuable reference for the parameter optimization of the DM..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 514001 (2015)
Analysis of Influence Factors of Array Laser-Screen
Chen Youxing, Hou Jinliang, Zhao Hui, and Yue Xiufang
Laser-screen is one of the main equipments for measuring projectile-velocity, aiming at the test requirements of dot array laser-screen, the influences on the process of system debugging and measurement are studied. According to the principle of velocimetry, the influences of load resistance, illumination distance, illLaser-screen is one of the main equipments for measuring projectile-velocity, aiming at the test requirements of dot array laser-screen, the influences on the process of system debugging and measurement are studied. According to the principle of velocimetry, the influences of load resistance, illumination distance, illumination angle and angle of emission on received signals are analyzed. While the pellet passes through the device, the ideal mathematical model is established based on the actual situation of receiving component, and the relative error under different dropout voltages of timing is obtained to analyze the influence of the uniformity of the screen on the whole velocity-measuring system. The theoretical modeling and experimental analysis provide the theoretical basis and reference, for the structure design and the application of dot array laser-screen in the velocity-measuring system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 514002 (2015)
Pulse Width Tunable Dark Pulse Laser Based on Semiconductor Optical Amplifier
Pan Honggang, Yu Jinlong, Wang Wenrui, Liu Yi, and Yang Enze
A dark pulse optical fiber laser with tunable pulse widths based on semiconductor optical amplifier (SOA) is demonstrated. By injecting a portion of light to the SOA from the output of the optical fiber laser, due to the nonlinear polarization rotation of the SOA, the output pulse experience different polarization evolA dark pulse optical fiber laser with tunable pulse widths based on semiconductor optical amplifier (SOA) is demonstrated. By injecting a portion of light to the SOA from the output of the optical fiber laser, due to the nonlinear polarization rotation of the SOA, the output pulse experience different polarization evolutions and dark pulse is obtained. By changing the length of the feedback cavity, dark pulses with different widths are obtained. Nonlinear polarization rotation effect of the SOA and the mechanism of the dark pulse production are analyzed. In the experiment, the output of the dark pulse with tunable widths is observed. By changing the length of the feedback cavity, under the condition of fixed repetition frequency(11.31 MHz), dark pulses with tunable widths of 5.91~22.34 ns are obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 514003 (2015)
Machine Vision
Monocular Camera Three Dimensional Reconstruction Based on Optical Flow Feedback
Li Xiuzhi, Yang Ailin, Qin Baoling, Jia Songmin, and Qiu Huan
A monocular three dimensional(3D) reconstruction technique based on optical flow feedback is proposed to achieve fast and accurate 3D stereoscopic modeling in the real scene. Corresponding pixel pairs are robustly matched by inter-frame optical flow fields and the five-point algorithm is employed to determine relative A monocular three dimensional(3D) reconstruction technique based on optical flow feedback is proposed to achieve fast and accurate 3D stereoscopic modeling in the real scene. Corresponding pixel pairs are robustly matched by inter-frame optical flow fields and the five-point algorithm is employed to determine relative pose of the moving camera, therefore sparse point cloud is generated and initial crude mesh is built. In the proposed method, multi-view reconstruction is implemented from perspective of vision method on motion analysis. The reconstruction model is fed-back to the reconstruction process and the model is deformed by utilizing the bias-driven of each view. The coarse and inaccurate original mesh surface is adjusted to the exact surface through a dense non- rigid deformation. Under the compute unified device architecture, the optical flow algorithm is optimized in parallel mode by using the graphic processing unit hardware and real- time performance of the reconstruction algorithm is significantly improved. The experimental results obtained in realistic indoor scenario demonstrate the effectiveness and accuracy of the proposed algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 515001 (2015)
Mobile Robot Monocular Visual Odometry Algorithm Based on Ground Features
Wang Ke, Jia Songmin, Li Xiuzhi, and Xu Tao
A mobile robot localization method based on the monocular vision is proposed. According to the planar ground assumption, a plane homography-based mobile robot pose estimation model is established with the KLT corner detection and tracking algorithm. Under the framework of random sample consensus algorithm, the initial A mobile robot localization method based on the monocular vision is proposed. According to the planar ground assumption, a plane homography-based mobile robot pose estimation model is established with the KLT corner detection and tracking algorithm. Under the framework of random sample consensus algorithm, the initial location of the mobile robot is realized by solving the above model. On this basis, a triangular structure of corner features is adopted for plane parameter estimation. Combined with M-estimation algorithm,the non-planar feature information is excluded efficiently and the location accuracy of mobile robot is improved.The indoor experimental results demonstrate the effectiveness and feasibility of the proposed algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 515002 (2015)
An Iterative Closest Point Algorithm Based on Biunique Correspondence of Point Clouds for 3D Reconstruction
Wei Shengbin, Wang Shaoqing, Zhou Changhe, Liu Kun, and Fan Xin
Registration of point clouds is one of the key technology of optical three-dimensional (3D) profilometry. Registrations without markers are always realized by using iterative closest point (ICP) algorithm. To improve the performance of ICP algorithm, an improved ICP algorithm based on the biunique correspondence of poiRegistration of point clouds is one of the key technology of optical three-dimensional (3D) profilometry. Registrations without markers are always realized by using iterative closest point (ICP) algorithm. To improve the performance of ICP algorithm, an improved ICP algorithm based on the biunique correspondence of point clouds is proposed. The establishment of biunique point pairs is introduced, and the transformation of coordinates between point clouds are derived. By using a handheld 3D scanner to scan a statue consisting of high-frequency and low-frequency profiles, then 92 frames of point clouds are obtained. Using the proposed improved ICP algorithm, 82 frames of point clouds are successfully registered. Three representative variants of ICP are applied to register these 92 frames for comparison. Experimental results demonstrate that the proposed algorithm has advantages of strong robustness, high convergent speed and high convergent accuracy, which is useful for fast reconstruction of 3D models..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 515003 (2015)
Materials
Effects of Cation-Substitution in Lu3Ga5O12∶Tb3+ System on the Crystal Structure and Luminescent Properties
Zhu Xianzhong, and Chu Chenglin
Lu3Ga5O12∶Tb3+ phosphors is synthesized by the high temperature solid state reaction, and the effects of substitution of Y3+/Gd3+ and Al3+ for Lu3+and Al3+ respectively on the crystal structures and luminescent properties of the phosphors are investigated. Lu3Ga5O12∶Tb3+ shows pure garnet phase, and the excitation specLu3Ga5O12∶Tb3+ phosphors is synthesized by the high temperature solid state reaction, and the effects of substitution of Y3+/Gd3+ and Al3+ for Lu3+and Al3+ respectively on the crystal structures and luminescent properties of the phosphors are investigated. Lu3Ga5O12∶Tb3+ shows pure garnet phase, and the excitation spectrum contains two broad bands called A-and B-bands and some lines assigned to the transitions of Tb3+4f8→4f75d1 and 4f8→4f8, respectively. Under ultraviolet (UV) light, the emission spectrum consists of Tb3 + characteristic emission lines corresponding to 5D4→7FJ and 5D3→7FJ transitions. For (Lu, Y)3Ga5O12∶Tb3+system, with the increase of Y3+, the crystal structure remains with a slight lattice expansion, the red-shift of A-and B-bands occurs, the interval between the two bands decreases, and the intensity of excitation and emission enhances. Similar but more obvious changes occurs in (Lu,Gd)3Ga5O12∶Tb3+system in a range of Gd3+ concentration from 0 to 0.75 with respect to Lu3+. The energy transfer of Gd3+→Tb3+ is observed. For Lu3(Ga,Al)5O12∶Tb3+system, with the increase of Al3+, the garnet phase structure remains with a lattice shrinkage, the red- shift of A- and B- bands occurs, the interval between the two bands increases, and the intensity of excitation and emission improves. The difference in ions radii between the cations, and the change of the crystal field environment Tb3 + caused by cations substitution are the main factors of affecting the properties of the phosphors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 516001 (2015)
Synthesis and Properties of Li2BaSiO4:Sm3+ Phosphor
You Panli
Sm3+-doped Li2BaSiO4∶Sm3+ phosphor is prepared by a solid-state reaction method. Through X-ray diffraction (XRD) data, Li2BaSiO4∶Sm3+ with hexagonal crystal structure is synthesized at 850 ℃, and the diffraction peak of XRD move to the high- angle and the lattice distortion increase as increasing the mass fraction of SSm3+-doped Li2BaSiO4∶Sm3+ phosphor is prepared by a solid-state reaction method. Through X-ray diffraction (XRD) data, Li2BaSiO4∶Sm3+ with hexagonal crystal structure is synthesized at 850 ℃, and the diffraction peak of XRD move to the high- angle and the lattice distortion increase as increasing the mass fraction of Sm3+ ions. The Li2BaSiO4∶Sm3+ material has strong absorption at 330~500 nm and can be excited effectively by near ultraviolet and blue light emitting diode (LED) chip. The maximum emission intensity of Sm3+ and the minimum ratio of I650/I607 are attained by doping 1.5% Sm3+ . The results suggest that Sm3+ ions prior to occupy Ba2+ with symmetric lattice in the Li2BaSiO4 materials. The emission peaks located at 518, 563, 607, 650 and 707 nm are presented under the excitation of 402 nm. The spectrum of 518 nm is attributed to defect luminescence in Li2BaSiO4∶Sm3+ , while others are derived from the emission of 4G5/2→6HJ (J=5/2，7/2，9/2，11/2) of Sm3+ . The color coordinate of Li2BaSiO4∶Sm3+ sites in yellow range due to defect emission, and the formation mechanism for defect luminescence is discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 516002 (2015)
Influence of Annealing Temperature on the Dielectric Function of Quantum Dots Doped Glass
Chen Gang, and Xu Jun
In order to reveal the influence of annealing temperature on the photoelectric characteristic of PbSe quantum dots doped glass produced by a melt-annealing technique, experiments are carried out to compare the influence of different nucleation time and crystallization temperature. The transmission electron microscope iIn order to reveal the influence of annealing temperature on the photoelectric characteristic of PbSe quantum dots doped glass produced by a melt-annealing technique, experiments are carried out to compare the influence of different nucleation time and crystallization temperature. The transmission electron microscope images show that a certain amount of PbSe crystals are crystallized in the glass. While the degrees of crystallization, particle size and density have some slightly difference. A procedure combined the Mie scatter theory and the Kramers-Krnig relation is used to calculate the real and imaginary parts of the dielectric function from the experimental absorption spectrum. The calculation results indicate that the annealing temperature has obvious influence on the absorption coefficient and the refractive index. So the suitable annealing temperature and duration are the important factors in the preparation process of quantum dots doped glass with excellent photoelectric properties..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 516003 (2015)
Near-Infrared PbSe Quantum Dots-Doped Sodium-Aluminum-Borosilicate Silicate Glass Prepared Optimally by Melting Method of Two-Step Heat Treatment
Cheng Cheng, Huang Ji, and Xu Jun
PbSe quantum dots (QDs) in the sodium- aluminum- borosilicate silicate glass are successfully prepared by using a melting method of two- step heat treatment. The size of obtained QDs distributes within 3.63~4.33 nm and with the doped volume ratio of 2% in the glass. The optimal heat treatment temperature is determined PbSe quantum dots (QDs) in the sodium- aluminum- borosilicate silicate glass are successfully prepared by using a melting method of two- step heat treatment. The size of obtained QDs distributes within 3.63~4.33 nm and with the doped volume ratio of 2% in the glass. The optimal heat treatment temperature is determined by using a differential thermal analysis. The crystallization, particle size and distribution of the QDs in the glass are observed by X- ray diffractometer and transmission electron microscopy. The absorption and photoluminescence (PL) spectra of the QDs are also measured by ultraviolet (UV)-visible-near infrared (NIR) spectrophotometer and fluorescence spectrometer, respectively. There is evidence to show that only when the first heat-treatment time is between 3~5 h and the temperature is 500 °C, the glass has PL emission, ranging in 1220~1279 nm and with full width at half maximum (FWHM) of 200 nm. For the second heat treatment, the optimal time and temperature are 10 h and 540 °C, respectively. An empirical formula is given for the PbSe QD size depending on the first heat treatment time. The method of PbSe QD doped glass can help to form QD doped fiber devices with high gain in the future..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 516004 (2015)
Terahertz Dielectric Properties of CaCu3Ti4O12 Ceramics
Dai xiusong, Zhao Zhenyu, He xiaoyong, and Shi Wangzhou
Owing to the rapid development of capacitor for terahertz (1 THz=1012 Hz) electronics, the THz dielectric properties of different granular CaCu3Ti4O12 (CCTO) ceramics are investigated experimentally. It is found that the dielectric constant ε r of CCTO of small particles (Φ＜2 μm) is below 700, while exceeds 2000 for laOwing to the rapid development of capacitor for terahertz (1 THz=1012 Hz) electronics, the THz dielectric properties of different granular CaCu3Ti4O12 (CCTO) ceramics are investigated experimentally. It is found that the dielectric constant ε r of CCTO of small particles (Φ＜2 μm) is below 700, while exceeds 2000 for larger granular (Φ >10 μm) CCTO in the frequency range below 1 MHz. Correspondingly, the dielectric loss of CCTO is from 0.1 to 0.6. In THz frequency range, however, different granular CCTO ceramics exhibts the same value of εr ( εr =72±3). The ionic polarizability dominates εr , so that it is insensitive to the grain-size of CCTO. However, the larger grain- size increases the scattering cross- section, which enlargers the total extinction ratio of transmission so as to increase the dielectric loss in THz frequency range. It is found that the small granular CCTO is a potential dielectric materials for the application of THz capacitors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 516005 (2015)
Medical Optics and Biotechnology
A Method of Improving Imaging Quality of Full-Field Optical Coherence Tomography
Zhu Yue, Gao Wanrong, and Guo Yingcheng
A full-field optical coherence tomography (FF-OCT) system is reported, which has the capability of generating in vivo optical sectional images. The system is based on a Linnik white light interference microscope illuminated by tungsten halogen lamps, in which identical microscope objectives are used for both illuminatiA full-field optical coherence tomography (FF-OCT) system is reported, which has the capability of generating in vivo optical sectional images. The system is based on a Linnik white light interference microscope illuminated by tungsten halogen lamps, in which identical microscope objectives are used for both illumination and detection in reference and sample arms. Measured axial and lateral resolution of the developed system is 1.3 μm and 0.89 μm respectively. A 640 pixel × 480 pixel CCD camera is used to capture interference signals with imaging depth of 80 μm. A single chip-based control system is developed to modulate phase between both arms with the intention of higher signal-to-noise ratio (SNR) and faster acquisition speed, en face and 3D images of onion cells are presented, acquisition time is reduced from 60 s to 4 s per en face image and the SNR is improved from 18.36 dB to 23.30 dB compared with the system without it. The spherical aberration introduced by high-numerical aperture objectives and refractive index mismatch is considered theoretically and a compensation method is proposed. After compensating the spherical aberration experimentally, more details are shown in the en face images of onion cells (SNR is improved from 25.41 dB to 29.54 dB). Cell-level in vivo images of human finger skin are also presented. The imaging of liver tissue is performed, which demonstrates the potential value of FF-OCT in the early diagnosis of cancer. The apparatus proposed and developed will be helpful for the design of the practical device as a fast diagnostic means instead of the traditional frozen-section method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 517001 (2015)
Optical Design and Fabrication
Near Field Optical Modeling of LED and Design Optimization for Direct-Type Backlight Optical System
Qian Keyuan
Accurate measurement of physical properties of LED light source and an appropriate modeling are crucial for LED optical system design and computer simulation. The characteristics of common light source model are analysed. A comparative analysis of the design and simulation results for an actual optical system is given Accurate measurement of physical properties of LED light source and an appropriate modeling are crucial for LED optical system design and computer simulation. The characteristics of common light source model are analysed. A comparative analysis of the design and simulation results for an actual optical system is given caused by the deviation of actual LED light source characteristics from that of an ideal point light source and simple plane surface light source. A feedback method of lens design consisted of internal and external refractive surface is presented for a real direct- type backlight system with a white LED light source luminance data. Simulation results show that the uniformity of illumination reaches 0.83 when the distance-height ratio is 5.5 and the source area is near 1.7 mm×1.7 mm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 522001 (2015)
Study on Optimal Scale of Average Netted Dot Density for Light Guide Plate
Huang Bingle, Guo Tailiang, Chen Enguo, and Xu Sheng
The definition of best average netted dot density(BANDD)is proposed based on the research of the pattern of the netted dot for light guide plate(LGP), in order to elaborate the optimal design for the netted dot of LGP. A backlight module(BLM) is modeled in the light simulation software based on the theory of LGP guidinThe definition of best average netted dot density(BANDD)is proposed based on the research of the pattern of the netted dot for light guide plate(LGP), in order to elaborate the optimal design for the netted dot of LGP. A backlight module(BLM) is modeled in the light simulation software based on the theory of LGP guiding light, a group of differently uniform netted dot density (NDD) are applied in the model to test the effect on performance, the results indicate that the NDD from 0.1 to 0.4 relatively balances efficiency and uniformity. Further more the layout of the netted dot in the scale mentioned above is optimized to improve the uniformity; the results of simulation state clearly with the NDD from 0.2 to 0.35 can reach the requirement of uniformity in development stage. The corresponding experimental samples are made; the result of the experiment demonstrations that the BANDD is located in 0.25, it agrees well with the theoretical predictions. It has certain guiding significance that the conclusion of the study are applied in the actual development, and will accelerate the procedure of BLM and reduce the counts of designing editions, and cost down the development expense of the BLM..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 522002 (2015)
Research of Micro-Ienses Packing Strategy on Spherical Surface
Pang Wubin, Huang Wei, Wang Xinhua, and Jia Shuqiang
An universal perturbed icosahedral projection packing method is presented to solve spherical surface packing problem. First of all, original packing positions is obtained by using icosahedral points projection on its concentric spherical surface. Then, using chord ratio and packing density as merit values, perturbed poAn universal perturbed icosahedral projection packing method is presented to solve spherical surface packing problem. First of all, original packing positions is obtained by using icosahedral points projection on its concentric spherical surface. Then, using chord ratio and packing density as merit values, perturbed points moving strategy is used to optimize these initial positions. Finally, universal property of this method is tested by changing the number of packing points. In addition, this method is compared with another packing method, so called hexagonal density packing along longitude and latitude, which is based on local strategy. The result shows that this method is rather effective when the packing solid angle is large and the number of packing lenses is huge, the chord ratio can be reduced below 0.17, and the packing density can be increased above 75%, accompanied with outstanding symmetry, an excellent imaging performance is guaranteed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 522003 (2015)
See-Through Video Glass Based on Cascaded Waveguide Combiner
Han Xinyan, and Yu Feihong
A compact see-through video glass optical system based on cascaded waveguide combiner is designed. This optical system is composed of cascaded waveguide combiner, illumination system and eyepiece system. Cascaded waveguide combiner is a new configuration, having an angle selecting film. It can eliminate the ghost imageA compact see-through video glass optical system based on cascaded waveguide combiner is designed. This optical system is composed of cascaded waveguide combiner, illumination system and eyepiece system. Cascaded waveguide combiner is a new configuration, having an angle selecting film. It can eliminate the ghost images of the semitransparent waveguide. Illumination system for LCOS achieves 92.3% uniformity. Considering modulation transfer function, spot diagram, field curvature, distortion and lateral color, eyepiece system is analyzed. The parameters of the see-through video glasses are listed as follows: LCOS microdisplay resolution: 825 pixel×480 pixel, the total weight of optical system: 135 g. Within a 20 mm exit pupil distance and 8 mm ×8 mm eye motion box, system can achieve 30° field of view, under the drive circuit power consumption of 1 W, the brightness is 3000nit..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 522004 (2015)
Optical Devices
Sensing Model and Performance of the Surface Defect Photonic Crystal with Porous Silicon
Chen Ying, Fan Huiqing, Wang Wenyue, Zhu Qiguang, and Chen Weidong
The photonic crystal structure containing surface defect with porous silicon is proposed, in which the defect cavity on the surface is established by introducing the porous silicon layer and the absorbing medium layer, and the sensing region of the sample detected is formed by the use of the efficient carrying mechanisThe photonic crystal structure containing surface defect with porous silicon is proposed, in which the defect cavity on the surface is established by introducing the porous silicon layer and the absorbing medium layer, and the sensing region of the sample detected is formed by the use of the efficient carrying mechanism of the porous silicon. Because of the absorption of ZnS, the light corresponding to the resonant wavelength is absorbed and the defect peak is obtained in the reflection spectrum. The back propagation neural network is adopted to optimize the thickness of porous silicon globally. The relationship model between the concentration of the sample detected and the defect peak wavelength is established according to the Goos-Hanchen shift and the sensing performance is analyzed. The simulation results show that the reflectivity of the defect peak decreases from 31.23% to 0.00129% and the Q value can attain to 1537.37 after the optimal design of structural parameter. The sensitivity of the sensor structure is about 2.5 nm at per 1% mass fraction, which can provide effective theory guidance for the detection of the concentration and composition of samples..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 523001 (2015)
Support System Study of Rectangular Mirror
Li Haixing, Ding Yalin, and Zhang Hongwen
Support system design for large size rectangular mirror is one of the most challenging technical points during development of off-axis three-mirror anastigmatism (TMA) optical imaging sensor. The rectangular third mirror with the size of 760 mm×320 mm is the study object. Key mechanism of the temperature effect onSupport system design for large size rectangular mirror is one of the most challenging technical points during development of off-axis three-mirror anastigmatism (TMA) optical imaging sensor. The rectangular third mirror with the size of 760 mm×320 mm is the study object. Key mechanism of the temperature effect on the mirror′ s optical surface deformation is studied thoroughly. The relationships between temperature range and the mirror blank′ s and back support part′ s linear expansion coefficient difference, mirror blank′ s capacity on interface mechanical load, rigidity of the flex structure which connects mirror blank and back support part, are established. During development of the mirror support system, a two-axis flex support structure which is composed of two perpendicular single axis circular flexures is proposed, and finite element analysis (FEA) is also employed to evaluate the mirror′s optical surface error and model frequency of this mirror sub-assembly. In the mean time, sine scan test is used to verify the FEA result of mirror sub-assembly′s model frequency. Under combination of 1g self gravity load and 10 ℃ temperature variation, the maximum FEA value of the mirror optical surface root-meansquare(RMS) error is 13.4 nm, and it meets the proposed requirement λ 45 ( λ = 632 nm ). FEA result and test value of the lowest model frequency of the mirror sub-assembly are 128.67 Hz and 124.1 Hz, respectively, it is higher than the proposed requirement of 100 Hz and meets design objective..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 523002 (2015)
Physical Optics
Generation of Arbitrary Vector Beams by Full Control of Light
Liu Guowei, Yang Yanfang, He Ying, Zheng Xiao, and Luo Zhuyu
We propose a method named as full control of light to generate arbitrary vector beams by modulating all the parameters of the spatial distributions of an optical field. Two reflective phase-only liquid crystal spatial light modulators can be used to modulate all the parameters of light including the phase, amplitude anWe propose a method named as full control of light to generate arbitrary vector beams by modulating all the parameters of the spatial distributions of an optical field. Two reflective phase-only liquid crystal spatial light modulators can be used to modulate all the parameters of light including the phase, amplitude and polarization (polarized rotation and ellipticity). Theoretically, we provide the Jones matrix of full control of light. Then the grayscale that is loaded on the spatial light modulator can be calculated according to the designed vectorial optical field. Experimentally, different vector beams containing amplitude and/or polarization modulations are successfully generated and tested using polarization measurement to verify the feasibility of this method of full control of light..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 526001 (2015)
Remote Sensing and Sensors
Automatic Registration of Urban Laser Point Cloud with Aerial Image Data Based on Straight-Lines
He Peipei, Wan Youchuan, Yang Wei, and Qin Jiaxin
In view of the imaging mechanism differences between the laser point cloud and image data, as well as existing registration primitives accessibility features, the registration based on features is the mainstream algorithm to refine the transformation of the two data sets. The corner points and edges of buildings are frIn view of the imaging mechanism differences between the laser point cloud and image data, as well as existing registration primitives accessibility features, the registration based on features is the mainstream algorithm to refine the transformation of the two data sets. The corner points and edges of buildings are frequently used as characteristics. In order to deal with the weakness of building edge detection and reduce matching- related computation, a new automatic registration method based on airborne LiDAR data and high-resolution aerial image of the road information is proposed. Vector road centerlines are extracted from raw LiDAR data and projected onto related aerial images with the use of coarse exterior orientation parameters (EOPs). The corresponding image road features of each LiDAR vector road are determined with the improved total rectangle matching approach. The endpoints of the conjugate road features obtained from the LiDAR data and aerial images are used as ground control points in space resection adjustment to refine the EOPs. Experimental results show that this method characterized by the road features can not only extract fewer features, but also improve the efficiency of data processing in autoregistration of aerial imagery with airborne LiDAR data..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 528001 (2015)
Scattering
Research on A Novel Fast Imaging Dynamic Light Scattering Method for Nanoparticle Size Measurement
Liu Lili, Cai Xiaoshu, Zhang Jie, and Xu Chengze
A novel imaging dynamic light scattering method for nano-particle sizing which greatly reduces the data processing time is proposed. In this method the scattered signal of particles is recorded as images. Two images of spacial distribution of the scattered light signal are taken in a very short time interval, and the cA novel imaging dynamic light scattering method for nano-particle sizing which greatly reduces the data processing time is proposed. In this method the scattered signal of particles is recorded as images. Two images of spacial distribution of the scattered light signal are taken in a very short time interval, and the correlation coefficient of the two images is calculated, and then the particle size can be determined by the particle size- correlation coefficient curve at the corresponding delay time. Compared to the traditional dynamic light scattering method, the measure time is shortened from hundreds of seconds to microseconds, and the data processing time is shortened to the milliseconds. Three different latex nano-particles (79、482 and 948 nm) are measured in the experiments of nano-particles, and the measurement error is less than 7%, which illustrates that the real-time online measurement and data-processing can be truly realized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 529001 (2015)
Research on Rayleigh Scattering by Charged Particles
Zhang Zijia, Pan Qi, and Chen Haixiu
Research of the scattering of electromagnetic waves by charged particles is significant for the thorough understanding of electromagnetic field and the detection of the clouds and lightning warning. According to the theory of the Mie scattering of the charged particles and the characteristics of the Rayleigh scatteringResearch of the scattering of electromagnetic waves by charged particles is significant for the thorough understanding of electromagnetic field and the detection of the clouds and lightning warning. According to the theory of the Mie scattering of the charged particles and the characteristics of the Rayleigh scattering, the simplified scattering coefficient is derived, that is related to the surface conductivity and the electromagnetic impedance in vacuum. The results calculated by both Mie and Rayleigh formula for particles with a small size parameter are concordant. The charges carried on the surface of the particles increase the surface conductivity. When the surface conductivity reaches magnitude of millisiemens, it will have obvious effects. As the surface conductivity increases, the scattering efficiency will have bigger change. When the conductivity reaches a certain value, the ratio of scattering efficiency of the charged and neutral particles with a small size parameter tends to be stable. For the charged droplet, the ratio will tend to be twenty four which is related to the dielectric constant of the particles..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 529002 (2015)
Spectroscopy
Effect of Annealing on Transient Photoluminescence Properties of Microstructured Black Silicon
Cao Liping, Chen Zhandong, Wu Qiang, Zhang Chunling, and Yao Jianghong
Effect of annealing on the properties of time-resolved spectra of photoluminescence (PL) and the decay in PL intensity of black silicon processed by femtosecond laser pulses in air is studied. The motion of photon-generated carriers and the property of defects in black silicon after annealing have been analyzed. By fitEffect of annealing on the properties of time-resolved spectra of photoluminescence (PL) and the decay in PL intensity of black silicon processed by femtosecond laser pulses in air is studied. The motion of photon-generated carriers and the property of defects in black silicon after annealing have been analyzed. By fitting the PL decay profile with double exponential function, the probable mechanism of spectral change of black silicon due to annealing is given. The increase in PL intensity of black silicon after annealing is the result of the increased oxygen defects resulting from the radiative recombination rate of nonequilibrium carriers. A theory of thermal diffusion is put forward to explain the observation that the PL intensity of black silicon increases with the annealing temperature. The increasing time constants and the ratio of the slow decay process are attributed to the fact that some defects on the microstructured surface and within silicon material have been eliminated and restored by annealing that leads to the increasing of the surface bound state, thus reducing the density of nonradiative recombination centers. The ratio of radiative recombination increases, resulting in the increase in PL intensity of annealed black silicon. The best annealing condition for the PL of black silicon found is annealing at 800 ℃ for 30 min in vacuum..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 530001 (2015)
Theoretical Study on High Efficiency Blue Emitting Materials Based on Firefly Enol-Form Oxyluciferin Derivatives
Min Chungang, Leng Yan, Cui Xiaoying, Yang Xikun, Huang Shaojun, Wang Shaohua, and Ren Aimin
To obtain the blue light emitting materials which exhibit high emission efficiency, good balanced electron and hole injection and good hole transport ability, a set of firefly enol-form oxyluciferin analogs with pyrrole, thiophene, furan, imidazole, oxazole instead of thiazole ring in benzothiazole fragment of enol-forTo obtain the blue light emitting materials which exhibit high emission efficiency, good balanced electron and hole injection and good hole transport ability, a set of firefly enol-form oxyluciferin analogs with pyrrole, thiophene, furan, imidazole, oxazole instead of thiazole ring in benzothiazole fragment of enol-form oxyluciferin is designed. A systematic investigation into them is carried out with the density functional theory and timedependent density functional theory. The calculated ionization potentials show that introducing pyrrole, thiophene, furan and imidazole can largely enhance the hole transport ability. By analyzing the hole and electron reorganization energies, it is found that the balance between the hole-transfer and electron-transfer is good. Five novel firefly enol-form oxyluciferin analogues in which the benzothiazole ring is replaced with indole (EIN), benzothiophene (ETH), benzofuran (EFU), benzimidazole (EIM) and benzoxazole (EOX) can all be used as blue light-emitting materials..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 530002 (2015)
Miniature Digital Micro-Mirror Device Hadamard Transform Near-Infrared Spectrometer
Wang Xiaoduo, Liu Hua, Dang Boshi, Quan Xiangqian, Xu Jialin, Xiong Zheng, Li Yunpeng, and Lu Zhenwu
A Hadamard transform near-infrared spectrometer used digital micro-mirror device (DMD) is proposed and designed. A grating is used for light diffraction, a DMD is applied instead of the traditional mechanical Hadamard masks for optical modulation, and an InGaAs single point detector is used as the optical sensor. SuitaA Hadamard transform near-infrared spectrometer used digital micro-mirror device (DMD) is proposed and designed. A grating is used for light diffraction, a DMD is applied instead of the traditional mechanical Hadamard masks for optical modulation, and an InGaAs single point detector is used as the optical sensor. Suitable length and width of the slit, incident angle of the grating and the focal length of lens are selected by analyzing some key influential factors to the spectrometer′s performance, such as resolution, utilization ratio of light energy, volume of the system and costs. Section optimization method is used during the design of the optical system, and then the images of slit on the DMD, the size of the spot on detector are analyzed. The simulation resolution is less than 4 nm， the spot size on InGaAs single point detector is smaller than 3 mm, and the size of the optical system is 75 mm×25 mm×85 mm . In order to improve the ability in detecting teeny light signal, a light collecting structure is proposed, which can improve the utilization ratio of light energy by 24.2% theoretically. The experiment results show that the spectral resolution of the system is better than 6 nm, and the light collecting structure can significantly improve the utilization ratio of light energy. It′s obvious that the spectrometer is high-resolution, portable and lowcost, which has broad application prospects..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 5, 530003 (2015)
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