Journals >Acta Photonica Sinica
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2019
Volume: 48 Issue 9
26 Article(s)
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Slip Sensing Unit Using Optical Fiber Bragg Grating
FENG Yan, WANG Feiwen, ZHANG Hua, XIAO Jiaming, and HU Ronghua
A slip sensing unit based on cantilever structure is developed. The Bragg wavelength shifts of three fiber Bragg gratings and variance of the wavelength difference are used to predict whether slip happens or not, so that the fluctuation of the contact force, the sliding rate and direction can be detected. The experimenA slip sensing unit based on cantilever structure is developed. The Bragg wavelength shifts of three fiber Bragg gratings and variance of the wavelength difference are used to predict whether slip happens or not, so that the fluctuation of the contact force, the sliding rate and direction can be detected. The experimental results show that the proposed slip sensing unit can detect micro slip within the range of 0.2~1 N of the contact force, whose minimum sensitivity is 3.8 pm/mm. The average relative errors between the experimental value and the theoretical value are 6%, 14% and 6.6% for the slip sensitivity, the slip speed coefficient and the contact force, respectively..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 906001 (2019)
Temperature Characteristics of Cascaded FabryPérot Interferometer Sensors Based on Vernier Effect
HOU Leyi, MAO Bangning, WANG Jianfeng, XU Ben, SHEN Changyu, and ZHAO Chunliu
Optical fiber Cascaded FabryPerot Interferometers (CFPIs) sensors based on vernier effect were manufactured by splicing a segment of Hollow Core Fiber (HCF) between two segments of Single Mode Fiber (SMF), and its temperature characteristics were investigated theoretically and experimentally. Simulation and experimentOptical fiber Cascaded FabryPerot Interferometers (CFPIs) sensors based on vernier effect were manufactured by splicing a segment of Hollow Core Fiber (HCF) between two segments of Single Mode Fiber (SMF), and its temperature characteristics were investigated theoretically and experimentally. Simulation and experimental results verify the phenomenon exists in CFPIs sensors, the interference spectra of some sensors based on vernier effect shift to longer wavelength while others shift to shorter wavelength when temperature increases. The phenomenon can be interpreted well based on the value D, which is defined as the Free Spectrum Range (FSR) difference of the cascaded FPIs. Under the condition that temperature increases, the positive or negative of D determines that the spectrum shifts towards longer wavelength or shorter wavelength. Besides, the investigation shows that D makes a great influence on temperature sensitivity. The temperature sensitivity improves with D decreasing. The temperature sensitivities of our experimental sensors are 163.8 pm/℃ and －75 pm/℃, which corresponding D are 0.055 nm and －0.456 nm, respectively. By optimizing the length of the HCF and the caudal SMF proportionally, a simple, compact, lowcost and highsensitivity CFPIs temperature sensor would be achieved..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 906002 (2019)
Interferometric Optical Fiber Water Level Sensing System for Oceanic Monitoring Applications
PANG Shuo, LUO Zhengchun, WANG Zhongmin, CHANG Tianying, DAI Guangbin, YU Miao, WU Chongjian, and CUI Hongliang
In order to achieve ocean water level monitoring for effective tsunami warning, an allfiber interferometric water level sensing system is proposed and demonstrated. According to the large range and fast response of ocean water level variation, an interference structure based on doublecollimator alignment and a linearIn order to achieve ocean water level monitoring for effective tsunami warning, an allfiber interferometric water level sensing system is proposed and demonstrated. According to the large range and fast response of ocean water level variation, an interference structure based on doublecollimator alignment and a linear frequencychirp based phase demodulation method are adopted, achieving the ocean water level measurement with large range, high precision and fast response. The experimental results show that the measurable range of the water level sensing system is 0~109.14 m, the measurement accuracy can reach ±1 cm, with the response time of 0.01 s. The proposed system is demonstrated to be suitable for ocean water level monitoring and tsunami warning..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 906003 (2019)
Algorithm of Phase Correction Based on Least Square Estimation for Optical Fiber FabryPerot Sensor
LIU Jiajing, TU Ziwei, ZHOU Ciming, and FAN Dian
To improve the demodulation precision and efficiency of fiberoptic FabryPerot sensor, a series of optical path differences are calculated by using the peaks of the interference spectrum, and the rough demodulation result and the additional phase are obtained according to least square estimation such that the varianceTo improve the demodulation precision and efficiency of fiberoptic FabryPerot sensor, a series of optical path differences are calculated by using the peaks of the interference spectrum, and the rough demodulation result and the additional phase are obtained according to least square estimation such that the variance of the optical path differences is minimized. The spectral additional phase is corrected to obtain the compensated optical path difference .The final demodulation result is made up of the rough optical path difference and the compensation optical path difference. The simulation results show that the error of the algorithm is less than ±2.5 nm. The FabryPerot high temperature experiment results show that when the temperature is raised from room temperature to 1 000℃, the algorithm demodulates the optical path difference precision to 5.4 nm, the corresponding temperature precision is ±0.36‰F.S., and the average calculation speed is 400 times faster than that of FFTMMSE at the same condition. The algorithm is characterized by high precision and high calculating speed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 906004 (2019)
Infrared Small Target Detection Based on Adaptive Doublelayer TDLMS Filter
ZHANG Yixuan, LI Ling, and XIN Yunhong
An infrared small target detection algorithm based on adaptive filter is proposed, which consists of twolayer Two Dimensional Least Mean Square Filter (TDLMS) filters: background removal and target extraction. The background template and target template are introduced, and the original infrared image is processed by TAn infrared small target detection algorithm based on adaptive filter is proposed, which consists of twolayer Two Dimensional Least Mean Square Filter (TDLMS) filters: background removal and target extraction. The background template and target template are introduced, and the original infrared image is processed by TDLMS filtering method. The background noise and clutter are eliminated effectively, while the target information is preserved as much as possible. In the implementation of TDLMS algorithm, an automatic stepsize adjustment algorithm is proposed. The optimal weights of TDLMS filters can be iterated by adjusting the adaptive stepsize through the statistical parameters of the image, and then fused with the weight template, which effectively enhances the detection effect of the target. The experimental results show that the method can adapt to target detection under different background, and effectively improve the detection performance of small infrared targets..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 910001 (2019)
Uncooled Infrared Stripe Noise Correction Algorithm Based on Multiscale Analysis and Weighted Least Squares
JIANG Ping, WANG Ende, JIN Lei, QI Kai, YI Chunlin, and HAN Bing
In order to improve the quality of infrared images while maintaining texture information to a greater extent, a multiscale analysis and weighted least squares method for stripe noise nonuniformity correction is proposed. The algorithm uses the weighted least squares method to smooth the image, applies the wavelet traIn order to improve the quality of infrared images while maintaining texture information to a greater extent, a multiscale analysis and weighted least squares method for stripe noise nonuniformity correction is proposed. The algorithm uses the weighted least squares method to smooth the image, applies the wavelet transform to extract the vertical component of the smooth image which is replaced with the vertical component of the original image subsequently, and reconstructs the corrected image by wavelet reconstruction. The proposed algorithm can accurately remove infrared noise without causing more troublesome "ghosting" problems. The proposed algorithm is experimented on multiple sets of different infrared image data, and compared with the stateoftheart destriping algorithms. The results show that the proposed algorithm has better visual effects and image quality evaluation parameters..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 910002 (2019)
High Density Mixed Noise Removal Algorithm Based on Gaussian Curvature Optimization and Nonsubsampled Shearlet Transform
WANG Manli, TIAN Zijian, GUI Weifeng, and WU Jun
In order to improve the observability of mine images corrupted by mixed noise, a highdensity mixed noise removal algorithm based on Gaussian curvature optimization and nonsubsampled shearlet transform was proposed. The local Gaussian curvature is used to optimize the mixed noise image to suppress the influence of salIn order to improve the observability of mine images corrupted by mixed noise, a highdensity mixed noise removal algorithm based on Gaussian curvature optimization and nonsubsampled shearlet transform was proposed. The local Gaussian curvature is used to optimize the mixed noise image to suppress the influence of salt & pepper noise on the noise distribution, which makes the mixed noise distribution approximate to a Gaussian noise distribution. Then, the nonsubsampled shearlet transform is used to decompose the image optimized by Gaussian curvature and implement adaptive hard threshold shrinkage to remove the Gaussian noise in the mixed noise. Finally, the local Gaussian curvature optimization and the nonsubsampled shearlet transform are executed iteratively to reduce the residual noise until the output image gradient energy satisfies the stop condition. Experiments show that the proposed algorithm can effectively remove the highdensity mixed noise composed of Gaussian noise and salt and pepper noise, and effectively suppress the PseudoGibbs phenomenon caused by shearlet transform denoising algorithms, and effectively reduce the noise of mine images..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 910003 (2019)
Traffic Monitoring Image Dehazing Algorithm Based on Wavelength Related Physical Imaging Model
WANG Yibin, ZHENG Jia, L Zhuowen, YAN Yu, and YUAN Yongjian
Conventional dehazing algorithms usually neglect the problem of uneven fog concentration, which is existed in the traffic monitoring image. To tackle this problem, a dehazing algorithm based on wavelength related physical imaging model is proposed. Firstly, a wavelength related physical imaging model is built for traffConventional dehazing algorithms usually neglect the problem of uneven fog concentration, which is existed in the traffic monitoring image. To tackle this problem, a dehazing algorithm based on wavelength related physical imaging model is proposed. Firstly, a wavelength related physical imaging model is built for traffic monitoring imaging process, in terms of the correlation between wavelength and fog concentration. Secondly, according to the correlation of color and wavelength, a transmission estimation strategy based on the maximal fuzzy correlation segmentation is designed. Considering the fuzzy property of overlapping intensities and spatial correlation of scenes, maximal fuzzy correlation is used for obtaining partition information of different scenes which helps to design the data term of graph cut and enable the implementation of graph cut. Such an image segmentation strategy incorporates the thresholdbased segmentation into the spatialbased segmention, ensuring the spatial correlation, improving the precision and further avoiding misclassfication of white object. Finally, the atmospheric light can be predicted by the sky region in the segmentaion result, and haze can be removed. The experiments tested on the 500 synthetic images and realworld images demonstrate that the proposed algorithm can improve dehazing precision by 7% at least and shorten running time by 15% roughly, comparing with exising dehazing algorithms. Hence, the proposed method can be used for image dehazing in the traffic monitoring system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 910004 (2019)
Simple Optical System Image Restoration Method Based on Phase Diversity
JING Wenbo, ZOU Huanhuan, ZHANG Jiaming, ZHAO Zhiyuan, and WANG Caixia
There are some problems in the simple optical system, such as blurring and distortion of the image due to the serious aberration. The imaging characteristics of the simple optical system are analyzed. A point spread function model with aberration and an image restoration model are established with the prior knowledge tThere are some problems in the simple optical system, such as blurring and distortion of the image due to the serious aberration. The imaging characteristics of the simple optical system are analyzed. A point spread function model with aberration and an image restoration model are established with the prior knowledge that the focal length and pupil aperture of the optical system are known. Only the focal plane and defocus surface images and the precise defocus amount are required, the image obtained by the simple optical system is reconstructed by the phase diversity method without the prior information of the point spread function. The experimental results show that the image quality evaluation index improvement rates of single lens, double lens and three lens system are 24.96%, 24.80% and 42.04%, respectively, and the restored image quality has been improved obviously..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 911001 (2019)
Realtime Interactive Computergenerated Integral Imaging Method Based on Ray Tracing
QIN Zhiqiang, ZHANG Wenge, JIANG Xiaoyu, YAN Xingpeng, and YAN Zhiqiang
To improve the realtime interactive display performance and flexibility of the computer generated integrated imaging, the integral light field viewing model consistent with the structure of the optical reconstruction system in integrated imaging is constructed. A reversely traced ray for each pixel in the elemental iTo improve the realtime interactive display performance and flexibility of the computer generated integrated imaging, the integral light field viewing model consistent with the structure of the optical reconstruction system in integrated imaging is constructed. A reversely traced ray for each pixel in the elemental image array is generated by integral light field viewing model, the elemental image array is efficiently shaded as all the rays are computed parallely through ray tracing technology. Experimental results show that, a point cloud model with 565 880 vertex, and a mesh model containing textures with 977 308 faces are optically reconstructed on the 4 K display system at a frame rate of over 40 fps, the system have interactive functions such as scaling, moving, rotation and fine adjustment. Getting rid of the virtual camera model, the method make realtime interaction more effective and convenient, and can be applied to the integral imaging based on lens array with different distribution patterns..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 911002 (2019)
Refocusing Calibration Method for Light Field Optical Sectioning Tomography System
ZHAO Dacheng, SHAN Liang, KONG Ming, HONG Bo, and LIU Wei
In order to accurately obtain the refocusing image of the depth position according to the parameter, a calibration method based on the step ruler is proposed. Taking the original image by the light field camera, the image sequence is obtained by the refocusing technique, and the scale surface of the image sequence is cIn order to accurately obtain the refocusing image of the depth position according to the parameter, a calibration method based on the step ruler is proposed. Taking the original image by the light field camera, the image sequence is obtained by the refocusing technique, and the scale surface of the image sequence is calculated by the definition evaluation function, to find the clearest image, complete calibration of the refocusing parameter. Evaluating the calibration results, the knifeedge method is used to calculate the Gaussian defocusing parameter of the refocused image. The value of this method is reduced by more than 25% compared with the method of the scale ruler, which can effectively improve the accuracy of refocusing of the light field camera. The sectioning imaging experiment was carried out, and the sectioning refocusing images under the two calibration methods were compared to verify that the refocusing results of the step ruler calibration are clearer and suitable for the light field optical sectioning tomography system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 911003 (2019)
Pixellevel Observation of Phase Profile in Liquid Crystal on Silicon Device by White Light Scanning Interferometry
QU Ming, ZHENG Junjie, LI Min, GUI Cong, and SONG Wuzhou
An improved Michelson white light scanning interferometry is demonstrated to be used to aquire the phase modulation characterization of the LCOS device and correct the gamma curve, and the phase profile of the phase gratings on the LCOS device can be observed in the pixel level. With a compensatory glass flat attached An improved Michelson white light scanning interferometry is demonstrated to be used to aquire the phase modulation characterization of the LCOS device and correct the gamma curve, and the phase profile of the phase gratings on the LCOS device can be observed in the pixel level. With a compensatory glass flat attached to the reference mirror, the limitation of the tiny coherent length of the white light is overcome and the contrast of the interference fringes is improved. Using the Morlet wavelet transform method to obtain the peak point of the envelope curve of the white light interference signals to reconstruct the phase profile, the actual phase resolution is 0.01π, and the horizontal resolution is 0.79 μm. Using the Logistics fuction to fit the phase profile of the binary grating which the phase modulation depth is 2π, the width of the flyback region is 11.49 μm. The linear phaseslope region and the flyback region are including in the blazed grating on the LCOS device with small pixels. The width of the flyback region is 8.81 μm and the diffraction efficiency is calculated to be 71.9% in the blazed grating whose period is 40 μm. Analyzing the blazed gratings with different periods, the result shows that the relative width of the flyback region is broadened and the diffraction efficiency is decreased with the smaller period of the blazed grating..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 911004 (2019)
Method for Inorbit Optical Axis Pointing Calibration of Micronano Remote Sensing Camera
WU Jun, LI Na, YUE Chunyu, MENG Peibei, DING Kaicheng, JIANG Hongjia, and LI Yingbo
Based on the principle of laser measurement and the characteristics of micronano cameras, a new inorbit pointing calibration method for micronano remote sensing cameras are investigated. This method adopts optical path and focal plane multiplexing technology to realize integration of calibration device and camera syBased on the principle of laser measurement and the characteristics of micronano cameras, a new inorbit pointing calibration method for micronano remote sensing cameras are investigated. This method adopts optical path and focal plane multiplexing technology to realize integration of calibration device and camera system. Through this method, realtime calibration on each scene remote sensing image becomes possible. This paper verifies this new method of inorbit pointing calibration using one new micronano remote sensing camera. Simulation results show that the optical axis pointing calibration accuracy does not exceed 0.2″, which satisfies the requirements of the camera image, controlling the plane positioning accuracy within 30 m. Through the preparation and calibration results of principle prototype, the principle and practical feasibility of this method are further proved. This method can help improving the quantitative application value of micronano remote sensing satellites..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912001 (2019)
Design of Dualband Adaptive Calibration Checkerboard Based on Peltier Effect
WANG Ziang, HUANG Fuyu, ZOU Changfan, LIU Bingqi, and WANG Yuanbo
In order to accurately calibrate the dualband camera system with visible light and infrared lens, reduce the number of calibration plates and increase the adaptability to the camera response band, a dualband adaptive calibration checkerboard based on the Peltier effect is designed, which solves the problem of the difIn order to accurately calibrate the dualband camera system with visible light and infrared lens, reduce the number of calibration plates and increase the adaptability to the camera response band, a dualband adaptive calibration checkerboard based on the Peltier effect is designed, which solves the problem of the difficulty in manufacturing largesize calibration plates. Different intensity infrared radiation is generated by controlling the current in the circuit, achieving the adaptation of the response band of the camera system. It can be seen from the images taken by the binocular ultrawide angle longwave infrared camera that the calibration checkerboard has a large number of points, which can meet the requirements of large field of view. Besides, the calibration corners are clear, the contrast is high, and the infrared radiation uniformity and the stability are good. After the performance test, the calibration corner reprojection error reaches the subpixel level, the calibration parameter error is within 1%, and distortion correction effect is good..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912002 (2019)
Field Calibration of Sunphotometer in Dunhuang Test Site
HUANG Dong, LI Xin, ZHANG Yanna, ZHANG Quan, ZHENG Xiaobing, and SUN Ling
In order to ensure the accuracy of aerosol optical characteristics observation in onorbit automatic calibration of satellites, field calibration techniques of sunphotometer in Dunhuang test site were studied, including Langley calibration based on relatively stable atmospheric conditions and cross calibration based onIn order to ensure the accuracy of aerosol optical characteristics observation in onorbit automatic calibration of satellites, field calibration techniques of sunphotometer in Dunhuang test site were studied, including Langley calibration based on relatively stable atmospheric conditions and cross calibration based on high precision reference instruments. The calibration results show that the maximum deviations of aerosol optical depth inversion from high precision sunphotometer compared with CE318 sunphotometer are within 0.015 and 0.01 respectively by Langley method and crosscalibration method. The effects of atmospheric conditions and instrument parameters on field calibration were calculated and analyzed. The calibrated high precision sunphotometer and CE318 sunphotometer were placed in Qinghai Lake for synchronous comparison observation. The maximum deviation of aerosol optical depth is within 0.01. The influence of field calibration error of sunphotometer in Dunhuang test site on onorbit calibration of satellite is less than 0.21%, which shows that the calibration results can meet the accuracy requirements of satellite onorbit automatic calibration..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912003 (2019)
Absolute Distance Measurement System Based on the Selfmixing Interferometry of a Threewavelength Optical Fiber Laser
WANG Yunzhi, XIE Fang, CHEN Longhui, XU Haibo, and LI Mingjia
An absolute distance measurement system based on the selfmixing interferometry of a threewavelength optical fiber laser has been presented and experimented. The optical fiber laser is consisted of three independent laser cavities and there is erbiumdoped fiber as a gain medium in each laser cavity. The three laser cAn absolute distance measurement system based on the selfmixing interferometry of a threewavelength optical fiber laser has been presented and experimented. The optical fiber laser is consisted of three independent laser cavities and there is erbiumdoped fiber as a gain medium in each laser cavity. The three laser cavities use fiber Bragg gratings as the reflectors and wavelength selectors, and three wavelengths have been emitted simultaneously. There is no laser mode competition between the three wavelengths so each of the three wavelengths has stable frequency and power. Absolute distance measurement can be realized based on the selfmixing interferometry of the three wavelengths and the coincidence of the phase decimal of the three wavelengths selfmixing interferometric signals. By the method of simulation analyzing, the difference between every two adjacent wavelengths should be equal approximately. In the experiments, the difference between every two adjacent wavelengths is about 10 nm. A step with the nominal height of 11 mm and the corrected value less than 2.7 μm was measured by the system. The measurement result is 11.000 059 mm. The standard deviation of twenty times repeated measurements of the absolute distance 13.000 090 mm is 4.4 nm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912004 (2019)
Influence of Fatigue of Piezoelectric Ceramic Actuators on Correction Bandwidth of Deformable Mirrors
XIE Li, WANG Jiaqiu, ZHONG Zheqiang, and ZHANG Bin
The fatigue effect of actuators of deformable mirrors would be generated under the longterm action of the alternating electric field in the process of the wavefront correction in adaptive optics systems. According to the error and openloop transfer functions of adaptive optics control systems and the fatigue characteThe fatigue effect of actuators of deformable mirrors would be generated under the longterm action of the alternating electric field in the process of the wavefront correction in adaptive optics systems. According to the error and openloop transfer functions of adaptive optics control systems and the fatigue characteristics of piezoelectric ceramic actuators, the influence of the fatigue of piezoelectric ceramic actuators on the delay time, correction bandwidth of deformable mirrors and system stability was discussed. The results show that the properties of piezoelectric, dielectric and electromechanical coupling of piezoelectric ceramic all decrease with the increasing of cycle times, in which the electromechanical coupling properties have the greatest influence on the delay time of the deformable mirrors. In the process of correcting the distortion wavefront by the deformable mirrors, both the error rejection bandwidth and the openloop bandwidth decrease with the increasing of the cycle of the piezoelectric ceramic actuators and the delay time of the deformable mirrors. Meanwhile, the variation range of phase margin increases gradually, resulting in the worsening of the stability of the system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912005 (2019)
Stray Light Suppression Technology and Optimization Algorithm of Distributed Photometric Measurement System
XUE Ping, HE Hai, and WANG Hongmin
The stray light affecting photometric measurement was analyzed by using geometrical optics analysis method. According to the characteristics of stray light reflection transmission, a concave narrow aperture array model with high refraction and reflection effect was designed by combining the approximate absolute blackboThe stray light affecting photometric measurement was analyzed by using geometrical optics analysis method. According to the characteristics of stray light reflection transmission, a concave narrow aperture array model with high refraction and reflection effect was designed by combining the approximate absolute blackbody structure theory and absorbance summation theory, so as to improve the ability of stray light suppression. Due to the different extinction effect of this structure under different aperture spacing, an adaptive inertial weight particle swarm optimization algorithm was designed to search for the optimal aperture spacing, so as to further improve the performance of the aperture array. On the basis of the above, the distributed photometric system based on the optimal suppression model was verified by simulation and experiment. The results show that measurement error of system from more than 10% to less than 1% compared with before. The system satisfies the corresponding international and national standards for the error requirements of light source measurement. It can be used as an effective means to further suppress environmental stray light in the existing environment..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912006 (2019)
Method to Improve Signal Extraction Capability of Hydroxyl Tagging Velocimetry in Supersonic Combustion Flow Field
SHAO Jun, YE Jingfeng, HU Zhiyun, ZHANG Zhenrong, LI Guohua, and LI Jingyin1
A new approaches of Hydroxyl Tagging Velocimetry(HTV) in the application of supersonic combustion flow field signal extraction from images with strong background noise was proposed. These approaches are consisted of three steps: signal recognition through Hough transformation processing, image segmentation using maximuA new approaches of Hydroxyl Tagging Velocimetry(HTV) in the application of supersonic combustion flow field signal extraction from images with strong background noise was proposed. These approaches are consisted of three steps: signal recognition through Hough transformation processing, image segmentation using maximum betweenduster variance algorithm based on Region of Interest (ROI), and tagging line extraction using a process combining skeleton extraction and direction template. Based on the above approaches, the image identification ability in the harsh combustion environment with strong background is improved, and the problem of insufficient accuracy in extracting hydroxyl effective signal is solved..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 912007 (2019)
Integrated Optical Waveguide MachZehnder Interferometer Power Frequency Intensive Electric Field Sensor
LI Jiawen, ZHANG Jiahong, XU Xiaoping, ZHAO Zhengang, and LI Chuan
For measurement of intensive power frequency electric field, an asymmetric optical waveguide MachZehnder interferometer based sensor was designed and fabricated with size of 80 mm × 18 mm × 7.5 mm. By tuning wavelength of the laser source, the drift of the working point caused by the environmental change canFor measurement of intensive power frequency electric field, an asymmetric optical waveguide MachZehnder interferometer based sensor was designed and fabricated with size of 80 mm × 18 mm × 7.5 mm. By tuning wavelength of the laser source, the drift of the working point caused by the environmental change can be compensated, and a static working point of π/2 is formed, which results the sensor working stably in the linear transmission point. An integrated electrooptic power frequency electric field sensor with shieling electrode was theoretically analyzed. According to the national standard GB/T127201991, a power frequency electric field test system was established, and the time domain dynamic range of the sensor was measured. Experiment results show that the sensor has a linear correlation coefficient of 0.997 from 0.35 kV/m to 125 kV/m, which is suitable for power frequency electric field measurement..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 913001 (2019)
A Compact Ti∶Sapphire Regenerative Amplifier with Bulk Material Stretcher
QIN Shuang, NING Xiaonan, and CHEN Jiucheng
A compact Ti∶sapphire regenerative amplifier with bulk material as pulse stretcher is designed. Compared with the traditional structure stretcher, the bulk material stretcher is more consise and stable in structure. The laser pulses are compressed by a grismpair which combines together the gratings and prisms. Under tA compact Ti∶sapphire regenerative amplifier with bulk material as pulse stretcher is designed. Compared with the traditional structure stretcher, the bulk material stretcher is more consise and stable in structure. The laser pulses are compressed by a grismpair which combines together the gratings and prisms. Under the laser pumping conditions of 25 W, 527 nm and 1 kHz, the single pulse energy of output is 3.5 mJ, the repetition rate is 1 kHz, and the pulse width is 30 fs. The stability measurement shows that the power fluctuation in 8 hours is less than 0.7%..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 914001 (2019)
Analysis of Cryogenic Characteristics of High Power Semiconductor Lasers
WANG Mingpei, ZHANG Pu, NIE Zhiqiang, LIU Hui, SUN Yubo, WU Dihai, and ZHAO Yuliang
A set of cryogenic measurement system for semiconductor lasers with microchannel structure was developed. The stable measurement of some vital parameters such as output power, electrooptic conversion efficiency and spectra of high power semiconductor lasers in the range from －60℃ to 0℃ were realized. Based on computaA set of cryogenic measurement system for semiconductor lasers with microchannel structure was developed. The stable measurement of some vital parameters such as output power, electrooptic conversion efficiency and spectra of high power semiconductor lasers in the range from －60℃ to 0℃ were realized. Based on computational fluid dynamics and numerical heat transfer methods, the heat dissipation performance of three cryogenic coolants, anhydrous ethanol, trichloroethylene and pentafluoropropane was simulated. The simulation results show that semiconductor laser bar with anhydrous ethanol as the coolant has the smallest thermal resistance(0.73 K/W) and the best temperature uniformity(temperature difference between emitters is 1.45℃) when the pressure drop is 0.47 bar. Anhydrous ethanol was used as system coolant, the maximum of ethanol flow rate was up to 0.5 L/min, and 5 semiconductor laser bars could work simultaneously in the system. Based on the cryogenic measurement system, the cryogenic characteristics of 976 nm semiconductor laser bar with microchannel structure at 6% duty cycle were investigated. The experimental results show that the output power of semiconductor laser bar is increased from 388.37 W to 458.37 W which the powerup ratio is 18.02%, the electrooptic conversion efficiency is increased from 60.99% to 67.25%, the efficiency is increased by 6.26%, and the central wavelength is shifted from 969.68 nm to 954.05 nm when the coolant temperature decreases from 0℃ to －60℃. The turnon voltage increases by 0.04 V, the threshold current decreases by 3.93 A, the series resistance increases by 0.18 mΩ, and the external differential efficiency increases by 11.84%. The analysis shows that the decrease of threshold current and the improvement of external differential efficiency are the main factors that promote the power and efficiency of semiconductor lasers at low temperature. This investigation shows that the cryogenic working mode of liquid microchannel cooling is an effective means to achieve high output power and high electrooptic conversion efficiency of semiconductor lasers..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 914002 (2019)
Microarea Analysis of Surface Contaminations of GaAs Photocathode in Preparation Process
FANG Chengwei, ZHANG Yijun, RONG Minmin, QIAN Yunsheng, DAI Qingxin, SHI Feng, CHENG Hongchang, and BAI Xiaofeng
Based on the ultrahigh vacuum interconnection setup for photocathode preparation and surface analysis, the activation experiments were performed on reflective GaAs photocathodes, and the microarea analysis of the photocathodes after chemical cleaning and Cs/O activation was implemented by the scanning focused Xray pBased on the ultrahigh vacuum interconnection setup for photocathode preparation and surface analysis, the activation experiments were performed on reflective GaAs photocathodes, and the microarea analysis of the photocathodes after chemical cleaning and Cs/O activation was implemented by the scanning focused Xray photoelectron spectroscopy. Micro regions of interest were located to be detected with the aid of the Xray beam induced secondary electron image, and the impurities on the surface were analyzed more accurately. It is found that the GaAs cathode samples after chemical cleaning would suffer from secondary contamination by the metal sheet, accompanied by a small amount of sodium and cesium. Surface analysis and activation experiments show that high temperature heating and Cs/O activation can not remove the sodium contamination, which can affect the desorption of arsenic on the surface, hinder the adsorption of Cs and O in the activation process, and finally reduce the photoemission performance of the activated cathode. The scanning focused Xray imaging technology is used to analyze the microarea of cathode surface, which would assist in investigating the change of surface composition before and after cathode activation more accurately..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 925001 (2019)
Design of Siliconbased Nanooptical Tweezers Based on Finite Element Simulation
GAO Kui, SONG Wuzhou, ZHU Chenjun, and XIA Mengrou
To solve the heat loss of the surface plasmon optical tweezers, an optical tweezers of siliconbased doublenanocylinder with nanoring is designed. The field enhancement effects of three different siliconbased nanostructures (siliconbased nanosphere, nanocylinder and nanoring) were calculated by finite element simulaTo solve the heat loss of the surface plasmon optical tweezers, an optical tweezers of siliconbased doublenanocylinder with nanoring is designed. The field enhancement effects of three different siliconbased nanostructures (siliconbased nanosphere, nanocylinder and nanoring) were calculated by finite element simulation at 1 064 nm incident light field. Then, according to the optical resonance mechanism of siliconbased nanostructures, a siliconbased doublenanocylinder optical tweezers with an electric field enhancement factor of 7.39 times is designed. On this basis, optical resonance coupling is generated between the center of the ring and the gap between the double nanocolumn of the optical tweezers by introducing nanoring to the optical tweezers, which makes the electric field enhancement factor reaches up to 11.9 times and forms a stable optical potential well. Finally, Maxwell's stress tensor method was used to capture and analyze polystyrene beads of different diameters in siliconbased optical tweezers. And the trapping force, trapping potential and capture stiffness of polystyrene spheres with a diameter of 25 nm at different positions were calculated and analyzed in the x, y and z directions. The designed optical tweezers of siliconbased nanocylindrical and nanorings can achieve good results for the capture of polystyrene spheres..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 926001 (2019)
Numerical Study of Radially Polarized Partially Coherent Spiraling Bessel Beam
HU Hanqing, WU Fengtie, HU Run, YANG Yanfei, LI Jianpeng, QIU Weibin, and CHEN Jing
Based on the crossspectral density and the unified theory of coherent and polarization, the intensity expression of the Radially Polarized Partially Coherent Spiral Bessel Beam (RPPCSBB) can be significantly deduced. The propagation properties of the beam were also investigated. The RPPCSBB transmits in a spiral path Based on the crossspectral density and the unified theory of coherent and polarization, the intensity expression of the Radially Polarized Partially Coherent Spiral Bessel Beam (RPPCSBB) can be significantly deduced. The propagation properties of the beam were also investigated. The RPPCSBB transmits in a spiral path with a fixed distance in free space by the theoretical analysis and numerical calculation. During the transmission, the beam gradually evolves from a spiraling hollow beam to a spiraling Gaussian beam, and the transmission distance is related to the coherence length. The corresponding beam polarization angle and degree are also related to the spiral radius and the coherence length, and the polarization degree relates to the transmission distance. However, the coherence length, transmission distance, and the spiral radius do not affect the distribution of the beam polarization ellipticity..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 926002 (2019)
Fabrication of Nearinfrared Laser Film Filter
LI Houjun, XU Junqi, WANG Jian, LI Mian, and SU Junhong
A 1.2~3μm band laser film filter was developed on doubleside polished Si substrate using the ion beamassisted thermal evaporation deposition technique. The film sample was designed combination of long wave pass filter film and antireflection film. The high and low refractive index materials are ZnS and MgF2 monolayeA 1.2~3μm band laser film filter was developed on doubleside polished Si substrate using the ion beamassisted thermal evaporation deposition technique. The film sample was designed combination of long wave pass filter film and antireflection film. The high and low refractive index materials are ZnS and MgF2 monolayer films, respectively. Considering the spectral properties and intensity distribution of electric field, the 1.064 μm high reflection and 1.2~3 μm antireflection long wave pass filter were designed by a TFCale software. The longpass film system structure and the antireflection film structure are G|4H2L1.5H2L2H1.5L2H4L|A and G|3.5H3.5L|A, respectively. The results show that the peak transmissivity can approach 98.48%, the average transmissivity is 92.35% at the wavelength of 1.2~3 μm, and the transmissivity is 5.09% at the 1.064μm band. By ion beam and annealing treatment, It was found that the appropriate processing parameters contributed to the improvement of the laser induced damage threshold, when the annealing temperature is 250℃, the laser induced damage threshold is 6.3 J/cm2. This research provides application value for the design and preparation of near infrared thin film filters..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 48, Issue 9, 931001 (2019)
