Journals >Infrared and Laser Engineering
Contents
2015
Volume: 44 Issue 11
55 Article(s)
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Research Article
Assembly technology of off-axis optical system
Jia Penglei, Chen Gang, Chen Xiaonan, and Pang Xuanming
To meet the assembling requirements of the optical system of a certain Helmet Mounted Display(HMD), features of the lens in manufacturing, testing and assembly were investigated. And finally, an effective way that could solve problems in assembly of off-axis optical system was proposed. With modern production technologTo meet the assembling requirements of the optical system of a certain Helmet Mounted Display(HMD), features of the lens in manufacturing, testing and assembly were investigated. And finally, an effective way that could solve problems in assembly of off-axis optical system was proposed. With modern production technologies, an adjusting device with five degrees of freedom was designed. After error analysis and active compensation to parallelism error of guide rail, the adjusting precision of angle for the device is 3.15″, while the displacement adjusting accuracy is about 1μm. Furthermore, surface modeling was brought into the design of lens tube, which adopted a thin shell and was divided in two parts, to get compact structure. After comparison, aluminum alloy was selected as the material for lens tube, and some essential analyses were given to the single tube unit. The results showed that the total mass of the tube unit is 195 g, while the maximum stress acting on it is only 1.5 MPa, with the deformation of 0.3 μm. It turned out that the solution satisfied the requirements of design..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3379 (2015)
[in Chinese]
Study on de-agglomeration of the silica microsphere
Tian Yuan, Yang Junjie, Lai Xue, Shan Xinzhi, and Sui Guorong
Silica microspheres are easily agglomerated in anhydrous and aqueous media, which would seriously affect the properties and correlative studies of these particles. In order to effectively investigate and improve the characteristics of silica microspheres, the de-aggregation technology is indispensable. Through analysisSilica microspheres are easily agglomerated in anhydrous and aqueous media, which would seriously affect the properties and correlative studies of these particles. In order to effectively investigate and improve the characteristics of silica microspheres, the de-aggregation technology is indispensable. Through analysis of the mechanism of this aggregation phenomenon, a method was proposed to de-agglomerate the large-scale-agglomerated silica particles by ten steps. Experimental results observed by Nikon microscopy indicate that this method could greatly improve the dispersity and stability of the particles..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3336 (2015)
Research of pipeline monitoring system based on fiber optic pressure sensor
Lv Jiabo, Xu Xiping, Cai Cunliang, and Zhang Shaojun
For the problem that it is difficult to find and locate the leakage or the blockage of the pipelines buried in the soil, combined with fiber optic pressure sensor with high sensitivity, high anti-jamming feature, a pipeline monitoring system was designed based on fiber optic pressure sensor. It used polarimetric pressuFor the problem that it is difficult to find and locate the leakage or the blockage of the pipelines buried in the soil, combined with fiber optic pressure sensor with high sensitivity, high anti-jamming feature, a pipeline monitoring system was designed based on fiber optic pressure sensor. It used polarimetric pressure sensor which consisted of single mode fiber optic coated with a suitable thermal expansion coefficient of the material to overcome ambient temperature perturbation well. The pressure sensitive probes with modular design were distributed in pipeline every 20 meters to form an array of source signal point. Combined with lattice array data reconstruction and "interpolation positioning algorithm" to determine the location of faults. The results indicate that the system of fiber optic pressure sensor can effectively overcome the adverse effects of temperature changes on the sensor measurement. Within the range of 5.5 km, the positioning accuracy of fault point is within ±1 m..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3343 (2015)
[in Chinese]
A method of generating high precision large dynamic range distance simulation pulse
He Yun, and Xu Wenyuan
Among the existing motheds of generating distance simulation pulses, digital delay circuit can only achieve the accuracy of ns order, while analog delay circuit does not have enough delay range used as distance simulation pulse. In order to realize delay of high precision and large dynamic range to produce the distanceAmong the existing motheds of generating distance simulation pulses, digital delay circuit can only achieve the accuracy of ns order, while analog delay circuit does not have enough delay range used as distance simulation pulse. In order to realize delay of high precision and large dynamic range to produce the distance simulation pulse of laser range finder, based on the analysis of the current circuit, the circuit structure combining both the digital circuit and analog circuit was proposed in this article, which would satisfy both the high accuracy and large dynamic range. Its accuracy and repeatability were tested, and the results can reach 2 μs-4 ms range of delay and 0.1 ns delay precision, which can simulate the distance of 300 m-600 km and achieve the distance accuracy of 1.5 cm. The method of generating distance simulation pulse proposed in this article can solve the problem of incapable of achieving high precision and large dynamic range simultaneously, existing in current distance simulation circuit..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3408 (2015)
Analysis of influencing factors for precision of all-weather optical axis parallelism detection
Zhou Leigang, Liang Ting, and Gao Licong
To improve the precision of the infrared sensor, the chamber structure, circuit and data processing was optimized. The chamber structure of the infrared gas sensor was redesigned and optimized by the experiments and optical simulation. Three differential amplifier circuits were chosen to eliminate the system's noisTo improve the precision of the infrared sensor, the chamber structure, circuit and data processing was optimized. The chamber structure of the infrared gas sensor was redesigned and optimized by the experiments and optical simulation. Three differential amplifier circuits were chosen to eliminate the system's noise, and the secondary difference look-up table was used to process the data, and a new infrared methane sensor was designed by those measures. The experiments were performed to obtain the new sensor′s performance in the volume fraction 0%-3% of the methane. Results showed that the response time has been reduced to 20 s, the detection sensitivity was also improved, and the detection error was controlled within ±0.04%. After comparing the similar products at home and abroad, it is clear that this new designed sensor exhibits enhanced performances including higher detection sensitivity, lower detection error and shorter response time..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3413 (2015)
Fast calibration parameters of Fabry-Perot etalon by laser linear frequency sweep
An Panlong, Zhao Ruijuan, Liu Zhengguang, Zhang Xufeng, and Li Yijun
Fabry-Perot etalon is a precision optical instrument. Due to its narrow spectrum and high fineness, it is widely used in measuring the fine distance, signal detection and analysis and so on. Therefore, the quick measurement and accurate calibration of parameters of Fabry-Perot etalon has become very important in numeroFabry-Perot etalon is a precision optical instrument. Due to its narrow spectrum and high fineness, it is widely used in measuring the fine distance, signal detection and analysis and so on. Therefore, the quick measurement and accurate calibration of parameters of Fabry-Perot etalon has become very important in numerous optical research and accurate calibration steps. To aim at the parameters measurement of the Fabry-Perot etalon, the experimental calibration scheme was designed and the narrow linewidth laser (linewidth<1 kHz) was used. Moreover, the high-performance digital oscilloscope DPO4104B(1 GHz, 5 GS/s) was applied to directly test and calculate the parameters of etalon. This paper accurately calibrated the free spectral range, the full width at half maximum, the fineness, quality factor and the sweeping constant of the etalon. At last, two results of different schemes were compared. This paper can provide relevant technical reference for the fast and accurate parameters calibration of Fabry-Perot etalon..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3418 (2015)
Simulation of terrestrial target response function for satellite laser altimeter
Wang Liangxun, Zhou Hui, Li Zile, Liu Guogeng, Wang Hong, and Wang Yapei
The Terrestrial Target Response Function(TTRF) of satellite laser altimeter is the key factor for evaluating its performance. According to the distribution characteristics of transmitted Gaussian laser beam and the target response function, the methods of using equal-interval concentric rings and dividing circumferenceThe Terrestrial Target Response Function(TTRF) of satellite laser altimeter is the key factor for evaluating its performance. According to the distribution characteristics of transmitted Gaussian laser beam and the target response function, the methods of using equal-interval concentric rings and dividing circumference uniformly were utilized to achieve the discrete triangular mesh of target. Based on the homogeneity of the triangular mesh and error model about characteristic parameters of TTRF, a new parameter selection method of TTRF was presented in terms of the simulation error index. In light of geosciences laser altimeter system(GLAS) parameters, the TTRF waveform distribution of planar target with three typical slope targets(3° and 12.5° and 12.5°) and multiple planar targets were simulated, by restricting the allowance error of its characteristic parameters within 2%. The calculated error is less than 1.16%, which proved that the method on simulation of TTRF is correct. The results have some application values for the simulation on received signal waveform of laser altimeter, data inversion and the performance evaluation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3424 (2015)
Optical online detection method of oil and suspended matters in sewage
Li Chenyang, Duan Fajie, Xu Fei, and Jiang Jiajia
The pollution of excessive sewage of oil production is harmful to the soil environment and aquatic resources. It is necessary to monitor the water quality of oilfield, indentify the pollutant index and reduce the pollution of environment simultaneously. Based on transmission and scattering theory of near-infrared lightThe pollution of excessive sewage of oil production is harmful to the soil environment and aquatic resources. It is necessary to monitor the water quality of oilfield, indentify the pollutant index and reduce the pollution of environment simultaneously. Based on transmission and scattering theory of near-infrared light, a measurement model was proposed to test oil and suspended matter concentration in sewage at the same time. An appropriate light wavelength was selected, which was employed to realize the photoelectric detection using three-wavelength method. Furthermore, a plug-in online monitoring system was developed to carry out the experiments. The experimental results show that the proposed method has the advantages of high accuracy and reliability, and the developed system can simultaneously detect the components of oil and suspended matter in the sewage, and the deviation error of the system is less than 6% in comparison with the conventional method of infrared luminosity to detect the components of oil and the weighting method to detect the suspended matter in sewage. Therefore, the proposed method provides great reference for application in practice..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3431 (2015)
Effect of point spread functions on star centroid error analysis
Jiang Liang, Zhang Yu, Zhang Liguo, Zhang Xingxiang, and Ren Jianyue
Star centroid systematic error is called pixel frequency error, whose period is the width of the pixel. The analysis of the distribution of systematic error is useful in error compensation. Point spread function is the main factor which affects the distribution of systematic error. Traditionally the Gauss point spread Star centroid systematic error is called pixel frequency error, whose period is the width of the pixel. The analysis of the distribution of systematic error is useful in error compensation. Point spread function is the main factor which affects the distribution of systematic error. Traditionally the Gauss point spread function is used in the frequency analysis of the systematic error, but its reasonability has not been taken into consideration. With real star image considered, the Giancarlo point spread function was compared with the Gauss point spread function. Then the Giancarlo point spread function was used in the spacial frequency analysis of star centroid systematic error, and the theoretical formulas of the systematic error was obtained. Compared with the result of the traditional frequency analysis, an item that modulated the amplitude of the S curve distribution was added to the theoretical formulas, and that made the x coordinate systematic error distributed as an S curve along x axis and the amplitude of S curve changed along y axis. A simulation under a condition with noise was carried out, and the result was in accordance with the frequency analysis of this article. Finally an experiment is done, the result of the experiment is compensated for according to the theoretical formulas, the star centroid accuracy is improved by 54.42%, which is better than the traditional sine curve fitting compensation method..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3437 (2015)
Compact real-time online oil spill detection system based on surface plasmon resonance
Zheng Yan, Sun Yufeng, Xing Liyun, Dai Guangbin, Chang Tianying, Xia Liangping, Wang Min, Lang Jinpeng, and Cui Hongliang
The design and preliminary investigation of a real-time, online, all-weather accurate monitoring system for the early detection and warning of difficult-to-detect, inchoate, small-area oil spills were presented. The scheme is based on a miniaturized surface plasmon resonance (SPR) device. The system used a light sourceThe design and preliminary investigation of a real-time, online, all-weather accurate monitoring system for the early detection and warning of difficult-to-detect, inchoate, small-area oil spills were presented. The scheme is based on a miniaturized surface plasmon resonance (SPR) device. The system used a light source with a non-scanning angle modulation to ensure that the light cover the incident angle range of variation related to the samples under test. With a fixed range of sample refractive indices, corresponding to most of the known crude and refined oil products, the parameters for the detector through optimization of the central wavelength and the incident angle of the light source were obtained, as well as related parameters of the prism by a combinational simulation using commercial software packages MATLAB and ZEMAX. Through modeling and simulation, followed by preliminary experiments a basic model for the system feasibility was arrived for the proposed purpose..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3446 (2015)
Amelioration and simulation of coincidence counting towards intensity correlation imaging
Gao Xin, Li Xiyu, Feng Lingjie, and Tang Jia
The research aims to offer a solution to raise the detecting SNR of coincidence counting in intensity correlation imaging method and to obtain a clear image of high-orbit satellite. A simplified model of coincidence counting in intensity correlation was built based on the Hanbury Brown & Twiss Effect and the photoeThe research aims to offer a solution to raise the detecting SNR of coincidence counting in intensity correlation imaging method and to obtain a clear image of high-orbit satellite. A simplified model of coincidence counting in intensity correlation was built based on the Hanbury Brown & Twiss Effect and the photoelectric conversion semi-classical model. As well as the influence on the detecting SNR of coincidence counting caused by the time measurement error of detection equipment, the effect of coincidence window and the observed spectral shape was analyzed. Furthermore, an optimization on window function according to these observing conditions was offered. Finally, the coincidence window′s effects on detecting SNR with the Monte-Carlo method were simulated. The simulation result shows that, by practicing the process of optimized coincidence window in intensity correlation imaging, the detecting SNR increases 39.2 times more than that with traditional method. The detecting SNR and the image quality of dim target can be efficiently improved as well by the window optimization..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3454 (2015)
Analysis and verification of structure stability and thermal stability of a bracket of star sensors
Jiang Fan, Wu Qingwen, Wang Zhongsu, Miao Jianyu, Guo Liang, Chen Liheng, and Yang Xianwei
To verify the effect on accuracy of star sensors by deformation of the bracket of star sensors in space, structure stability and thermal stability of the bracket were investigated. Structural properties of the bracket were analyzed by FEM and then the temperature data in worst case on orbit were mapped to the structureTo verify the effect on accuracy of star sensors by deformation of the bracket of star sensors in space, structure stability and thermal stability of the bracket were investigated. Structural properties of the bracket were analyzed by FEM and then the temperature data in worst case on orbit were mapped to the structure model. Based on the temperature data, the thermal deformation of bracket was figured out and vectors of optic axes of star sensors were obtained by least square method. Finally experiment was conducted to verify the analysis. Results indicated that fundamental frequency of star sensors and the bracket was 429 Hz with the difference less than 2% from the analysis and the max variety of the optical axes after vibration test was no more than 5″. The max temperature change of the bracket in orbit was less than 2 ℃ and the max variety of the optical axes was about 4″-5″ which was similar to the analysis. Both the ground test data and orbit data demonstrate that the bracket of star sensors has good structure stability and thermal stability which can meet the requirement..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3463 (2015)
[in Chinese]
Visible-extended InP/InGaAs wide spectrum response infrared detectors
Shi Yanli, Guo Qian, Li Long, Deng Gongrong, Yang Shaopei, Fan Mingguo, and Liu Wenbo
Standard InP/In0.53Ga0.47As short wavelength detectors has important application in high performance night vision owing to special spectrum response from 0.87 to 1.7 μm. In order to fully utilize the visible irradiation energy of night sky glow, the response wavelength can be extended to visible with the standard InP/IStandard InP/In0.53Ga0.47As short wavelength detectors has important application in high performance night vision owing to special spectrum response from 0.87 to 1.7 μm. In order to fully utilize the visible irradiation energy of night sky glow, the response wavelength can be extended to visible with the standard InP/In0.53Ga0.47As detector. By combining material structure design and substrate thinning processing technology, 320×256 visible-extended InGaAs wide spectrum detector were successfully prepared. Based on the detector, imagery demonstration was finished with different band filters. Different characterized information for the same target were indicated by detecting via short wavelength and visible filter respectively, at the same time, both visible and short wavelength information were obtained by wide spectrum detecting without band filter, the imagery behaved as visible and short wavelength dual band detecting. Consequently, target information and the recognition rate for the target will be improved dramatically by the visible-extended wide spectrum detector..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3177 (2015)
Single-photon detector based on GPQC with balanced APD-PIN junction capacitance
Liu Junliang, Li Yongfu, Zhang Chunfang, Wang Zuqiang, and Fang Jiaxiong
An NIR band single-photon detector(SPD), based on GPQC with balanced APD-PIN junction capacitance and InGaAs/InP avalanche photodiode, was designed which was able to work in wide gating frequency range. The SPD was driven by a pulsed gate signal of any frequency below 200 MHz, which had amplitude of 10 Vpp and pulse duAn NIR band single-photon detector(SPD), based on GPQC with balanced APD-PIN junction capacitance and InGaAs/InP avalanche photodiode, was designed which was able to work in wide gating frequency range. The SPD was driven by a pulsed gate signal of any frequency below 200 MHz, which had amplitude of 10 Vpp and pulse duration of approximately 1 ns. A novel GPQC was devised based on high-frequency PIN diode that had similar capacitive characteristics compared with APDs, such that the low-frequency portion of capacitive response of the APD was suppressed. Subsequently, a group of 9th ordered Bessel LC low-pass filters(LPF) were used to suppress the residual high-frequency portion. At the temperature of -52 ℃ and gating frequency ranged from 0.1-200 MHz, the dark count probability and afterpulse probability at detection efficiency of 10% were below 6×10-6/gate, 1.9%, respectively, and the highest detection efficiency reached 26.4%..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3181 (2015)
Thermal effects analysis and optimization design of high-power optical isolator
Hu Shuling, Zhao Dongwei, Niu Yanxiong, Wang Huanhuan, and Xiao Zeyu
In order to improve the performance of the operation of optical isolator at high power laser conditions, thermally induced depolarization effect in optical isolator was investigated with the use of Jones theory. An optical isolator system with external compensation crystal was proposed in this paper. Further the rules In order to improve the performance of the operation of optical isolator at high power laser conditions, thermally induced depolarization effect in optical isolator was investigated with the use of Jones theory. An optical isolator system with external compensation crystal was proposed in this paper. Further the rules of the changes of both isolation degree and thermal lens effects with the increasing of input optical power were also analyzed. The results show that thermally induced depolarization and thermal lens in magneto-optic crystal can be effectively suppressed by regulating the crystal axis direction and changing length of CaF2. Compared with traditional isolator, the isolation degree is increased by 16.3 dB and the power loss is reduced by 8% when the incident laser power is 100 W. Through the analysis result of this paper, the isolator structure can be optimized to both improve the isolation degree and reduce the power loss at high power laser conditions..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3186 (2015)
Band gap design of graphene photocathode
Li Shilong, Shi Feng, Zhang Taimin, Liu Zhaolu, Zhang Fan, Li Dan, and Ren Zhaoyu
In order to achieve graphene photocathode photoelectric conversion function, hexagonal boron nitride was doped in graphene in the form of hybrid superlattices nanoribbons. As can be seen from the band structure which was obtained by applying first-principles methods, the band gap of the superlattices was effectively reIn order to achieve graphene photocathode photoelectric conversion function, hexagonal boron nitride was doped in graphene in the form of hybrid superlattices nanoribbons. As can be seen from the band structure which was obtained by applying first-principles methods, the band gap of the superlattices was effectively regulated in a wide range(0-2.5 eV) by this means. The mechanism of band gap regulation was analyzed by the energy band structure and the charge density distribution. Furthermore, the present results were coincidence with the conclusion of Kronig-Penney model. With the increase of the h-BN proportion, the band gap engineering of graphene materials in this way, the band gap increases both zigzag edges superlattices nanoribbons and armchair edges superlattices nanoribbons. Besides, the band gap is almost independent of the width of nanoribbons, thus the size of the material can be more miniaturized. Moreover, the graphene photocathode with the gradient band gap characteristic can be made based on this approach, it can respond to different spectral ranges..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3191 (2015)
Application of genetic simulated annealing algorithm in parameters retrieval of dispersion equation for glass and crystal
Wang Anxiang, Zhang Xiaojun, and Cao Yunhua
According to the experimental data of K9 glass, ZnS crystal, MgF2 crystal and calcite crystal, the dispersion equations of the materials was established by the application of genetic simulated annealing algorithm to retrieval parameter of the modified sellmeier equation. Meanwhile, the differences in iteration searchinAccording to the experimental data of K9 glass, ZnS crystal, MgF2 crystal and calcite crystal, the dispersion equations of the materials was established by the application of genetic simulated annealing algorithm to retrieval parameter of the modified sellmeier equation. Meanwhile, the differences in iteration searching properties between the genetic simulated annealing algorithm and the genetic algorithms including standard genetic algorithm and multi-population genetic algorithm were compared. The results show that the genetic simulated annealing algorithm possesses the best optimization effect and stable performance. Finally, the dispersion equations of K9 glass and crystals obtained by genetic simulated annealing algorithm in one spectral region are used in another spectral region, and the fitted values of dispersion equation are in good agreement with experimental data, indicating that the dispersion equation has better extrapolation. Therefore, retrieval parameter of dispersion equation using genetic simulated annealing algorithm can be applied to other materials..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3197 (2015)
[in Chinese]
Design of LMCCD stereo mapping imaging
Yu Da, Liu Jinguo, Zhou Huaide, Long Kehui, Xu Dong, Chen Jiayu, and Kong Dezhu
Traditional three line array stereoscopic mapping is constrainted by orbit determination precision, attitude determination and control precision. Compared with it, the line-matrix CCD array(LMCCD) camera structure can improve the global stereo mapping precision without ground control points(GCPs). The related subject iTraditional three line array stereoscopic mapping is constrainted by orbit determination precision, attitude determination and control precision. Compared with it, the line-matrix CCD array(LMCCD) camera structure can improve the global stereo mapping precision without ground control points(GCPs). The related subject in detail, which included sensor configuration of stereo mapping of LMCCD, TDI working mode, PCB connecting method in narrow space, time scale generation and LMCCD synchronous control was described. The tests indicate that the LMCCD mapping camera can effectively reduced orbit and attitude measurement error. It meets the requirements of 1:50 000 scale maps without GCPs, and the performance can be improved in future application..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3393 (2015)
Study of synchronous sampling method for the relative spectral response of CCD
Cui Shanshan, Meng Binghuan, Qiu Zhenwei, Hong Jin, and Zou Peng
Continuously tunable monochromatic light source system is a dedicated test system for radiation parameter quantitatively of CCD, it can be used to measure the relative spectral response of CCD. Compared with the conventional test apparatus, the system is possible to achieve spectral resolution of 1 nm due to the use ofContinuously tunable monochromatic light source system is a dedicated test system for radiation parameter quantitatively of CCD, it can be used to measure the relative spectral response of CCD. Compared with the conventional test apparatus, the system is possible to achieve spectral resolution of 1 nm due to the use of the high-power xenon lamp. However, the lamp introduces instability problems. The conventional time-sharing measurement method can lead to poor measurement uncertainty, and can not meet the development needs of high-precision remote sensing instrument, and then a synchronous sampling method was proposed. Combining with the comprehender of the CCD calibration theoretical model, the measurement uncertainty of two methods was analyzed. The result shows that the synchronous sampling uncertainty is better than 1.03%, which increases 43% compared with the traditional time-sharing measurement method. Otherwise, it also has a contrast testing using the two methods. As a result, the relative spectral response curve of the CCD received by the synchronous sampling method is more flat, and the standard deviation is more low, which verify the correctness of the conclusions of the analysis..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3397 (2015)
Hyperspectral imaging remote sensing technology based on light weight unmanned helicopter platform
Ge Mingfeng, Qi Hongxing, Wang Yikun, Wang Yuxi, Ma Yanpeng, Cai Nengbin, and Shu Rong
A set of hyperspectral imaging remote sensing instruments was designed and completed. The system included hyperspectral imaging subsystem, data acquired and storage subsystem, monitoring and controlling on ground subsystem and position and orientation subsystem. To validate the performance of this system, a serial of eA set of hyperspectral imaging remote sensing instruments was designed and completed. The system included hyperspectral imaging subsystem, data acquired and storage subsystem, monitoring and controlling on ground subsystem and position and orientation subsystem. To validate the performance of this system, a serial of experiments had been made in Yantai and Yangzhou, high geometric resolution hyperspectral data was acquired. After analyzing the spectral characterization and geometric characterization of the acquired data, the results show that the position and orientation of unmanned helicopter have no distinct effect on spectral characterization, but the shake of motor of unmanned helicopter results in 4 pixels dither of the image in roll in the experiment. Finally, the geometric information of the hysperspectral data was corrected with the data of position and orientation subsystem and the error of the geometric correction was analyzed..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3402 (2015)
[in Chinese]
Design of 2.4 m solar simulator
Liu Jiaguo, Deng Rong, Wang Jingfeng, and Zeng Kesi
According to the demands of target characteristics research, a solar simulator with 2.4 m-diameter effective illuminated area was designed. Several targets were required that the illumination of irradiated area was not less than 0.3 solar constant; the collimating angle of outgoing beam was less than ±1°, theAccording to the demands of target characteristics research, a solar simulator with 2.4 m-diameter effective illuminated area was designed. Several targets were required that the illumination of irradiated area was not less than 0.3 solar constant; the collimating angle of outgoing beam was less than ±1°, the un-uniformity of irradiated surface was less than ±3% and the spectral mismatch error reached level C. The solar simulator consisted of four short-arc xenon lamps, four ellipsoidal reflectors, two flat reflectors, a group of optical integrator, and a collimating reflector. Software simulation analysis and experiment test were carried out for the design. Test results show that the diameter of effective illuminated area is 2.43 m, the mean illumination of irradiated area is 3 382 lx, the collimating angle of outgoing beam is ±0.97°, the un-uniformity of irradiated surface is ±2.8% and the spectral mismatch error reaches level C, which meet all the requirements..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3348 (2015)
Passive athermal design of dual-band infrared optical system
Jiang Lun, Hu Yuan, Dong Keyan, An Yan, Wang Chao, and Tong Shoufeng
In order to improve the target detection and recognition ability and enhance the environment adaptability of infrared optical system, thermal and chromatic properties of infrared optical materials in MLIR and LWIR were analyzed, acoording to the requirements of optical power distribution, axial achromatic aberration anIn order to improve the target detection and recognition ability and enhance the environment adaptability of infrared optical system, thermal and chromatic properties of infrared optical materials in MLIR and LWIR were analyzed, acoording to the requirements of optical power distribution, axial achromatic aberration and athermal aberration in the dual infrared band, properly lens materials were choosed based on the infrared chromatic diagram. And a dual-band infrared athermal optical system was designed. The system based on no cooled staring detector, the wavelength spectrum was 3-5 μm and 8-12 μm, The system consisted of four lenses, the effective focal length was 50 mm, the relative aperture was 1:1.25, the field view was 14° and the total optical focal length was just 67.9 mm. The result shows that between -50-60 ℃ and at the modulation transform function of 17 lp/mm is greater than 0.4 both in MWIR and LWIR, which prove that the system can work correctly at a large temperature range..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3353 (2015)
Design and analysis of 4 m SiC primary mirror turning device structure
Sun Jingwei, Wu Xiaoxia, Chen Baogang, and Li Jianfeng
The primary mirror turning device was designed to achieve the 180° revolution according to the special operating requirements of the 4 m SiC primary mirror. Firstly, it was determined that the turning device consisted of main body frame, axial supports and radial supports et al. The axial Whiffle-tree support forcThe primary mirror turning device was designed to achieve the 180° revolution according to the special operating requirements of the 4 m SiC primary mirror. Firstly, it was determined that the turning device consisted of main body frame, axial supports and radial supports et al. The axial Whiffle-tree support force and the radial strap force was theoretically analyzed when the primary mirror was in different zenith angles and the strap radial pressure was analyzed when the primary mirror was supported by the strap. Secondary, when the practical structure was designed, the finite element model was built and the rigidity of the main body frame was analyzed, and the mirror′s maximum stresses and the turning device′s maximum displacements were emphatically studied when the mirror axis was vertical and horizontal. The detailed structure of the whole turning device was designed. Finally, the turning device was machined and assembled according to the designed and analyzed results, and the mirror′s impact status was measured when the mirror was turning based on the accelerometer′s test. The practical application and the test result indicate that the design requirement of the turning device is achieved, and the direction for similar structure is provided here..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3358 (2015)
Opto-mechanical design and analysis of dual-band sharing aperture imaging system
Cheng Zhifeng, Liu Fuhe, and Xun Xianchao
In order to overcome the shortcomings of the airborne photoelectric payloads(visible light cameras and infrared thermal imager), which has too short focal length and independent with each other, the visible light/infrared sharing aperture system key technology were studied. With visible light and medium wave infrared dIn order to overcome the shortcomings of the airborne photoelectric payloads(visible light cameras and infrared thermal imager), which has too short focal length and independent with each other, the visible light/infrared sharing aperture system key technology were studied. With visible light and medium wave infrared dual band sharing the primary and secondary mirror, the optical system focal lengths were 1 500 mm and 750 mm respectively for the visible light and infrared wave. By choosing appropriate optical material and the reasonable support method, the system reflector support component's static and dynamic models were designed, the structure form was optimized. The thermal-structural-optical integrated analysis method was used to guide, evaluate and optimize the opto-mechanical systems design process, improve the natural frequency of the structure and enhance thermal stability range. The fundamental frequency of the structure is greater than 200 Hz, the surface precision of the system reflector reaches PV of λ/10 and RMS of λ/40. The optical system modulation transfer function(MTF) reaches 0.38 under influence of deadweight and uniform temperature change of ±5 ℃. The results indicate that the proposed design can meet the requirements of high structure natural frequency, the gravity and thermal coupling deformation, vibration resistance, etc, and the system has good imaging quality..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3366 (2015)
Design and analysis of using imaging optical system as laser transmitting antenna
Li Yanjie, Jin Guang, Zhong Xing, Liu Chunyu, and Wang Tiancong
To alleviate the load of the satellite and to deal with sudden trouble, research of co-aperture designing methods with which the space imaging optical system can be used as laser transmitting antenna was important. First, the co-aperture design method was proposed based on a given imaging optical system, and the opticaTo alleviate the load of the satellite and to deal with sudden trouble, research of co-aperture designing methods with which the space imaging optical system can be used as laser transmitting antenna was important. First, the co-aperture design method was proposed based on a given imaging optical system, and the optical coupling elements for meeting the imaging system to the laser transmitting request was analyzed when the laser transmitting system was based on EDFA. Then, the Gauss beam transmitting though the co-aperture system was analyzed, and the field distribution was given. Finally, the effect of distance changing between the coupling elements and imaging system on the transmitted laser were simulated. Result show that the co-aperture design can satisfy the imaging and laser transmitting request, and slightly adjusting the distance between the coupling elements and imaging system can change the transmitted waist and far-field peak energy without bad effect on the total transmitting energy, which make it possible for the system to satisfy different communicating mission..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3373 (2015)
Computer simulation for hybrid plenoptic camera super-resolution refocusing with focused and unfocused mode
Zhang Wei, Guo Xin, You Suping, Yang Bo, and Wan Xinjun
Light field is a representation of full four-dimensional radiance of rays in free space. Plenoptic camera is a kind of system which could obtain light field image. In typical plenoptic camera, the final spatial resolution of the image is limited by the numbers of the microlens of the array. The focused plenoptic cameraLight field is a representation of full four-dimensional radiance of rays in free space. Plenoptic camera is a kind of system which could obtain light field image. In typical plenoptic camera, the final spatial resolution of the image is limited by the numbers of the microlens of the array. The focused plenoptic camera could capture a light field with higher spatial resolution than the traditional approach, but the directional resolution will be decreased for trading. Two models were set up to emulate the 4D light field distribution in both the traditional plenoptic camera and the focused plenoptic camera respectively. The 4D light field images of the two kinds of plenoptic camera were simulated by the software ZEMAX. The differences of sampling methods of the two kinds of plenoptic camera were analyzed. A variable focal length microlens array was presumed to be used in plenoptic camera to implement both focused and unfocused light field imaging. Based on the recorded light field, the corresponding refocusing process was discussed then. The refocused images at different depth were calculated. A new method of enhancing the resolution of the refocused images by image fusion and super resolution theories was presented. A reconstructed all in-focus image with resolution of 3 times of traditional plenoptic camera and same depth of field was achieved finally..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3384 (2015)
[in Chinese]
Detection ability of infrared early warning satellite for ballistic missile in boost phase
Zhong Yu, Wu Xiaoyan, Huang Shucai, Wu Jianfeng, and Li Chengjing
To study the detection ability of infrared early warning satellite for ballistic missile in boost phase in the background of anti-missile operation, driven by the operational requirements, the tactical, technical and performance indices association structure of detection ability was built. The tactical and performance To study the detection ability of infrared early warning satellite for ballistic missile in boost phase in the background of anti-missile operation, driven by the operational requirements, the tactical, technical and performance indices association structure of detection ability was built. The tactical and performance indices were interconnected by the technical indices, and furthermore, some key technical indices models were built including Field of View(FOV), revisit time, detection probability, false alarm rate, Signal to Noise Ratio(SNR) and maximum operating range. The tactical, technical and performance indices association and its effect on detection ability were analyzed. Based on the typical radiation characteristics of target and background and the atmospheric transmittance, simulation examples showed the impacts and rules of different performance indices combination on maximum operating range and early warning time. The work can provide reference for evaluating anti-missile operation effectiveness and designing optimum satellite-borne infrared detection system..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3276 (2015)
Detecting performance effect on point target by scanning inhomogeneous
Gong Jinnan, Hou Qingyu, Deng Pan, and Zhang Wei
In order to deeply explore the relationship between detecting point target and scanning device，indicator to measure scanning feature called scanning inhomogeneous was established. According to the physical process of scanning imaging, an imaging model for scanning system with linear detector was established. Based on tIn order to deeply explore the relationship between detecting point target and scanning device，indicator to measure scanning feature called scanning inhomogeneous was established. According to the physical process of scanning imaging, an imaging model for scanning system with linear detector was established. Based on that model, scanning inhomogeneous affected on TDI detector for point target detecting was analyzed as the core of SNR. Firstly, integration timing order of single detector was set coordinating with the characteristics of scanning structure, and scanning inhomogeneous metric was established in the meanwhile. Then on the basis of the classical imaging model, an imaging model for point target in scanning system was established with the principle of integration order and detector systems. The SNR calculation formula was deduced combining with TDI working principle and detector noise model. With this formula, the performance of detecting point target was analyzed emphatically under conditions of optical systems, target scales and TDI levels. Finally from the view point of ensuring target detection performance, the upper limits of scanning inhomogeneous ratio in optical system was given. The established model reflects the characteristics of scanning detecting system accurately, and the analysis results are significant to guide for system design and index allocation..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3282 (2015)
Experimental study on visible and near-infrared spectrum polarization characteristic of soil moisture
Wang Xinqiang, Sun Xiaobing, Zhang Lijuan, Wang Jiejun, Xie Qiurong, and Ye Song
The self-constructed optical system was employed to study soil moisture and reflected light polarization characteristics in visible and near-infrared, to discuss the feasibility of the soil moisture detection based on light polarization property in more wave bands. The study results show: in the band of 600-800 nm, soiThe self-constructed optical system was employed to study soil moisture and reflected light polarization characteristics in visible and near-infrared, to discuss the feasibility of the soil moisture detection based on light polarization property in more wave bands. The study results show: in the band of 600-800 nm, soil moisture and the degree of reflected light polarization have correlation, especially when the soil moisture is more than or equal to 14% and less than or equal to 30%, the degree of reflected light polarization and soil moisture have proper linear relation. According to analysis of regression to measured data, linear model average standard deviation is less than 3%, having an advantage over the method of near infrared spectrum characteristic of 10% obtained in Ref.[5], accounting for the feasibility of the soil moisture detection on the basis of measuring light polarization in this band(600-800 nm), providing scientific basis for polarization remote sensing detection in wide-range soil water content..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3288 (2015)
Shared readout integrated circuit with memory-function background suppression
Hao Lichao, Chen Honglei, Li Hui, Chen Yiqiang, Lai Canxiong, Huang Aibo, and Ding Ruijun
Very long wave infrared(VLWIR) band widely used in remote atmosphere sounding applications is particularly rich in information about humidity, CO2 levels and provides additional information about cloud structure and the temperature distribution. In order to meet the requirements of VLWIR detectors at present stage, a sVery long wave infrared(VLWIR) band widely used in remote atmosphere sounding applications is particularly rich in information about humidity, CO2 levels and provides additional information about cloud structure and the temperature distribution. In order to meet the requirements of VLWIR detectors at present stage, a shared readout integrated circuit with memory-function background suppression was designed for its high injection efficiency, large dynamic range, stable detector bias, long integration time and some other advantages. In this design, the share buffered direct injection(SBDI) input circuit was used to minimize pixel area limitation and to maximize the efficiency of memory-function background suppression by 2×2 four neighboring pixels united. The total integration capacitor could reach up to 8.8 pF that has larger capacity, extended integration time, and increased the signal-to-noise ratio (SNR) of infrared focal plane array(IRFPA). At the same time, better contrast and dynamic range were also achieved. The final chip was fabricated with HHNEC CZ6H 0.35 μm 1P4M process technology. The simulation and test results show that the dynamic range is over 90 dB, the linearity is more than 99.9%, the integration time could be extended to 74 μs when the ROIC operates at the temperature of 50 K..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3293 (2015)
Design of infrared stealth coating of military vehicle based on photonic crystal
Li Wensheng, Zhang Qin, Fu Yanhua, and Huang Haiming
According to the surface temperature of military vehicles and for the infrared atmospheric window, a compound coating having photonic crystal structure was designed using common Si and LiF as the medium and in consideration of the respective dispersion relations. The calculation using the transfer matrix method showed According to the surface temperature of military vehicles and for the infrared atmospheric window, a compound coating having photonic crystal structure was designed using common Si and LiF as the medium and in consideration of the respective dispersion relations. The calculation using the transfer matrix method showed when the two medium are of 4 layers respectively, with geometric thickness of each layer is 0.800 μm and 1.900 μm, there would be a strict band gap within 8-14 μm, and the band gap had the following characteristics: With five or more medium layers, the band gap no longer changed substantially. When the geometric thickness of two medium increased, the band gap would have red shifts, width is wider and vice versa. The band gap between 8-14 μm always exist regardless the changes of the incident angle. These conclusion may provide a useful reference for the experiment study of the coating..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3299 (2015)
[in Chinese]
Characteristic of nonlinear distortion and predistortion compensation of semiconductor laser
Ke Xizheng, and Deng Lijun
In the laser communication, semiconductor laser is the most common light source device, which has a great influence on the performance of the whole system. The nonlinear model of the laser was modeled, then the linear method and the mapping function of the semiconductor laser were discussed. Finally, the I-V characteriIn the laser communication, semiconductor laser is the most common light source device, which has a great influence on the performance of the whole system. The nonlinear model of the laser was modeled, then the linear method and the mapping function of the semiconductor laser were discussed. Finally, the I-V characteristic curve of the laser was obtained according to the actual working conduction. Based on the Volterra series theory, the nonlinear model of the cemiconductor laser was established and the three polynomial coefficients were obtained. The method of predistortion compensation was designed to correct the nonlinear effect of laser, and the validity of the method was verified by experiments..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3204 (2015)
Delayed self-homodyne phase noise measurement system with optical coherent receiver
Zhao Zhenyang, Zhang Peng, and Tong Shoufeng
In coherent optical communication system, the phase noise of laser sources has been identified as a crucial characteristic that affects the receiver sensitivity of optical communication terminal. To characterize the laser sources phase noise of coherent optical communication system, three critical parameters which contIn coherent optical communication system, the phase noise of laser sources has been identified as a crucial characteristic that affects the receiver sensitivity of optical communication terminal. To characterize the laser sources phase noise of coherent optical communication system, three critical parameters which contained the field spectrum, phase-error variance and FM-noise spectrum were proposed for noise test in this paper. A delayed self-homodyne phase noise measurement system with optical coherent receiver was established and the optical communication system simulation had been achieved at the same time. The phase noise tests based on delayed self-homodyne phase noise measurement system which were used to evaluate the quality of coherent optical communication system had been performed on a narrow line-width semiconductor laser. Compared with traditional self-heterodyne narrow line-width measurement, this method can fully characterize the laser phase noise and achieve the requirement of resolution..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3211 (2015)
Influence of boundary condition and pump scheme on thermal effects of laser crystal
Meng Peibei, Yan Fanjiang, Li Xu, and Zheng Yongchao
The crystal′s thermal effects under different thermal boundary and pump structure were reported. In theory, based on operating characters of space laser, a thermal model satisfying crystal working state was set up. The temperature distribution of Nd：YAG crystal was simulated for diode laser with Gaussian beam distributThe crystal′s thermal effects under different thermal boundary and pump structure were reported. In theory, based on operating characters of space laser, a thermal model satisfying crystal working state was set up. The temperature distribution of Nd：YAG crystal was simulated for diode laser with Gaussian beam distribution side pumped laser, and the influence of thermal boundary condition, pump manner and pump parameters on thermal distribution was analyzed. With assumption that the thermal lens of crystal was thin lens, the thermal focal length was calculated theoretically and measured experimentally. With five-side annular pump structure, pump power of 4 500 W and pump repetition frequency of 10 Hz, the thermal focal length of Nd：YAG was about 9.5 m. Experimental results are in basic agreement with the simulated results..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3216 (2015)
Effect of sample temperature on laser-induced plasma radiation intensities
Chen Jinzhong, Wang Jing, Li Xu, and Teng Feng
Improving the intensity of laser-induced plasma emission spectrum is of great significance for enhancing the measuring accuracy of weak spectral signal and improving the detection sensitivity of low content elements in analysis material. The metal sample was heated in the first and ablated by the Nd:YAG nanosecond pulsImproving the intensity of laser-induced plasma emission spectrum is of great significance for enhancing the measuring accuracy of weak spectral signal and improving the detection sensitivity of low content elements in analysis material. The metal sample was heated in the first and ablated by the Nd:YAG nanosecond pulse laser with the wavelength of 1 064 nm in the air under the certain temperature. The plasma was produced. Then the line intensity and signal-to-noise ratio of spectrum were measured under the different sample temperature. The results show that, with the increase of sample temperature under the condition of laser energy for 200 mJ, plasma radiation increases and reaches the maxmum at the sample temperature of 150 ℃. Calculations show that the spectral line intensities of Mo, Cr, Ni and Mn increases by 54.56%, 72.43%, 70.29% and 54.01% respectively, and the spectral signal-to- noise ratios increases by 37.44%, 40.74%, 38.6% and 37.06% respectively compared with that of the room temperature. By observing the plasma images and measuring the temperature of the plasma, electron density and the sampleevaporation, the cause of the radiation enhancement of laser-induced metal plasma was discussed. Visibly, the rise of the sample temperature is a effective method for enhancing the quality of the laser spectrum..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3223 (2015)
Damage mechanisms of optical glass with gold nano-defects under laser irradiation
Pu Yunti, Wang Gang, Qiao Zhao, Hu Jiangchuan, and Ma Ping
Gold nano-defects(diameter=50-100 nm, AFM) were embedded in K9 optical glass by ion beam sputtering. The Laser-Induced Damage Threshold (LIDT) under 1-on-1 laser irradiation of the glass were investigated according to ISO 11254-1, respectively. The LIDT was defined as the incident pulse′s energy density when the damageGold nano-defects(diameter=50-100 nm, AFM) were embedded in K9 optical glass by ion beam sputtering. The Laser-Induced Damage Threshold (LIDT) under 1-on-1 laser irradiation of the glass were investigated according to ISO 11254-1, respectively. The LIDT was defined as the incident pulse′s energy density when the damage probability started to increase from zero (in joules per square centimeter), and it could be obtained by linear extrapolation of the damage probability data to zero damage probability. By analyzing the LIDTs, the LIDTs with optical glass embedded gold nano-defects were decreased from 26.6 J/cm2 to 15.5 J/cm2. Typical damage micrographs of optical glass embedded gold nano-defects were obtained by Nomarski microscope, showing vertical damage morphologies(explosion craters). Through the results of weak absorption(the weak absorption of optical glass embedded gold nano-defects was 47.33 ppm, 13 times to that of bare K9 optical glass), gold nano-defects formed strong absorption centers and caused local high temperature. Through theoretical calculation and simulation, damage mechanisms of optical glass with gold nano-defects under laser irradiation consisted two parts: (1) while in the optical glass embedded gold nano-defects, before the nano-defects boils, thermal stress exceeds the materials′ mechanical strength, leading to mechanical damage. (2) If the nano-defects are vaporized, steam pressure intensified the destruction of the material and caused local crack..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3229 (2015)
High-performance and narrow line-width nanosecond pulse laser amplifier for weak signal
Qi Gang, Xiong Shuidong, Liang Xun, and Lin Huizu
A single mode, linearly polarized, narrow line-width, nanosecond pulsed fiber laser in master oscillator power amplifier(MOPA) configuration was demonstrated and the experimental results agreed with the theory. A single-frequency continuous wave laser operating at 1 064 nm was modulated by an acousto-optic modulator(AOA single mode, linearly polarized, narrow line-width, nanosecond pulsed fiber laser in master oscillator power amplifier(MOPA) configuration was demonstrated and the experimental results agreed with the theory. A single-frequency continuous wave laser operating at 1 064 nm was modulated by an acousto-optic modulator(AOM) to obtain pulses as the seed of the master amplifier. The repetition rate of the pulsed seed was 50 kHz and the average power was 25 μW. In the pre-amplification stage, the effect of nonlinear effect, amplified spontaneous emission(ASE), parasitic lasing and pump saturation were analyzed by simulation. By optimizing the parameters of the MOPA system, the parasitic lasing was suppressed and the enlargement factor was increased effectively. In the experiment, the laser with pulse width of 64 ns and average power of 75 mW was achieved. Finally, the key factors that affect the performance of the sub-milli-watt weak signal amplifier were discussed..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3234 (2015)
Ablation rate of high frequency picosecond laser micromachining quartz substrated Al film
Jin Fangyuan, Chen Bo, E Shulin, Wang Haifeng, and Xing Yan
A 532 nm Nd:YAG 10 ps laser with output power of 3.7 W under frequency of 100 kHz was used for ablating quartz glass substrated Al film with thickness of micron dimension. The relationship between ablation rate and single pulse laser fluence was studied, the high fluence ablation and low fluence ablation regimes for piA 532 nm Nd:YAG 10 ps laser with output power of 3.7 W under frequency of 100 kHz was used for ablating quartz glass substrated Al film with thickness of micron dimension. The relationship between ablation rate and single pulse laser fluence was studied, the high fluence ablation and low fluence ablation regimes for picosecond laser ablating Al film were defined. The effect of spot overlapping rates on profilograms of grooves was analyzed, results showed that the ablation depth changed greatly with spot overlapping rate, and it was difficult to obtain ablation rate theoretically from this experiment. In order to improve the precision of ablated grooves and validate the accuracy of obtained ablation rate from Gaussian Linear method(GL), a muti-pass ablating method was put forward. The ablation rates calculated from GL were compared with Corrected Gaussian Linear method(CGL), experimental results showed that CGL was suitable for calculating ablation rates of grooves. The 3D profilogram of grooves in Al film ablated by 10 ps at different spot overlapping rates were simulated through CGL calculated ablation rates..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3238 (2015)
Effect of femtosecond laser micromachining on the roughness of cladding sidewalls
Li Rui, Yang Xiaojun, Zhao Wei, He Bin, Li Ming, Zhao Hualong, Zhu Wenyu, and Wang Ning
In order to enhance the surface finish of Laser Direct Deposition of metallic components, a method that applies femtosecond laser to fabricate the cladding layer was proposed in this paper. The effects of the energy density, distribution, and the overlapping ratio of the laser on the sidewall quality of the cladding laIn order to enhance the surface finish of Laser Direct Deposition of metallic components, a method that applies femtosecond laser to fabricate the cladding layer was proposed in this paper. The effects of the energy density, distribution, and the overlapping ratio of the laser on the sidewall quality of the cladding layer were studied in experiment. The experiment results show that the roughness of the achieved cladding side-wall layer can be smaller than 3 μm once the energy density in the region is 0.12-0.34 J/cm2 for the Gaussian-shape laser or 0.13-0.66 J/cm2 for the rectangle-shape laser. And the cladding sidewall layer fabricated by Gaussian-shape laser possessed more excellent surface quality than the product fabricated by rectangle-shape laser with same parameters. The roughness of the cladding sidewall layer decreases and then increases with the increase of the laser overlapping ratio, and the optimal region of overlapping-ratio is 78%-85%..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3244 (2015)
Laser propagation in optical system of hyper-spectral camera
Wang Yanbin, Chen Qianrong, Li Hua, Wang Min, and Zou Qianjin
As hyper-spectral cameras have been widely used in many fields such as industry, agriculture, scientific research, military, etc, it is urgent to develop the effective countermeasure, laser active suppressing jamming is presently one of the most effective technologies to cope with hyper-spectral cameras. Double-Gauss oAs hyper-spectral cameras have been widely used in many fields such as industry, agriculture, scientific research, military, etc, it is urgent to develop the effective countermeasure, laser active suppressing jamming is presently one of the most effective technologies to cope with hyper-spectral cameras. Double-Gauss optical system was taken as an example; first of all, the laser propagation in every lens was analyzed based on the propagation theory of Gaussian beam′s q parameter, and the energy distribution on the photosensitive surface of the system′s detector was obtained. The influences of laser launch parameters were subsequently investigated on the energy distribution. The results show that the laser spot on the photosensitive surface decrease with the increase of laser and hyper-spectral camera′s distance, however, with the increase of laser waist there is a minimum in the whole variation trend of laser spot. To achieve the better laser jamming effect, the minimum should be avoided in designing the laser waist. The research fruit can provide the theoretical basis and technical support for carrying out the experiment of laser jamming hyper-spectral imaging system and optimal design of laser launch parameter..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3250 (2015)
Analysis calculation and simulation on signal to noise ratio for underwater laser alarm
Lei Xuanhua, Cheng Jinfang, and Xiao Dawei
In anti-hunting early warning system, laser warning equipment was mainly used to identify the orientation of enemy laser signal. Water′s laser attenuation nature would reduce performances of alarm, its light absorption nature would lower SNR of the receiver and its scattering character would reduce the orientation precIn anti-hunting early warning system, laser warning equipment was mainly used to identify the orientation of enemy laser signal. Water′s laser attenuation nature would reduce performances of alarm, its light absorption nature would lower SNR of the receiver and its scattering character would reduce the orientation precision. Firstly, transmission equation theory was used to establish underwater transmission model of laser and then Fourier transform and plane wave expansion method were used to solve water transport equation. Lastly, light reciprocity principle and transmission equation were utilized to obtain the two-dimensional spatial intensity distribution model of the probe in the plane. Simulation had been used to calculate the response of detector to direct light and scattered light at different seawater environment in clean water, coastal water and turbid water. Results of the simulation show that the proposed method in this paper could be used to assess receptivity performance of the detector in underwater alarm system..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3256 (2015)
Analysis of underwater range-gated imaging system MTF
Hu Ling, Wang Xia, Yan Bo, and Li Shuaishuai
As great attention has been paid to the application requirements of the underwater imaging detection nation wide, underwater resources exploration and so on, it has been the target of the underwater imaging researchers to set up suitable underwater photoelectric imaging model. The corresponding modulation transfer funcAs great attention has been paid to the application requirements of the underwater imaging detection nation wide, underwater resources exploration and so on, it has been the target of the underwater imaging researchers to set up suitable underwater photoelectric imaging model. The corresponding modulation transfer function(MTF) and total system MTF model were established to explore underwater range-gated imaging system performance. Through the use of underwater laser range-gated imaging prediction model and programs, the imaging performance of the present market adopted super second generation and generation Ⅲ intensifiers were analyzed in comparison. Results indicate that the forward scattering light MTF and backscattering light MTF show a trend of gradual decline when detection range or gating time is increasing. The forward scattering light MTF declined faster. What′s more, system MTF shows a trend of gradual decline when detection range, special frequency or gating time is increasing. Generation Ⅲ intensifier has more advantages than super second generation intensifier..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3262 (2015)
A composite scanning method and experiment of laser radar
Ma Chenhao, Fu Yuegang, Gong Ping, Ouyang Mingzhao, and Zhang Shuhan
In traditional laser radar system, the imaging is influenced by repetition rate of selected solid-state laser as well as scanning bandwidth and scanning precision in the laser scanning system. In order to improve the scanning bandwidth and precision, DFB high-repetition-rate semiconductor laser which was amplified by EIn traditional laser radar system, the imaging is influenced by repetition rate of selected solid-state laser as well as scanning bandwidth and scanning precision in the laser scanning system. In order to improve the scanning bandwidth and precision, DFB high-repetition-rate semiconductor laser which was amplified by EDFA was adopted as the laser source firstly. Secondly, a two-stage composite laser scanning method had been proposed with combination of PZT and galvanometer. PZT got on meticulous scanning in small areas, then galvanometer was used to deflect and finish coarse scanning on the PZT scanning field and receiving the field. The scanning accuracy had been raised and the scanning field of laser radar had been expanded simultaneously. At last, azimuth of composite scanning laser radar is ±99 mrad, pitch angle is ±49.5 mrad. Angular resolution can measure up to 0.1 mrad, and the ranging precision can reach 0.159 m..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3270 (2015)
[in Chinese]
Space visual-monitor system for deployable antenna
Sun Yang, Li Jie, Zhang Ge, Ma Wei, and Qiu Lede
To establish large deployable antenna reliably and accurately in space, a space visual-monitor system was researched. Using the system, the deployment of the antenna could be monitored real-time, and an analysis was made for dynamics on the deployment process, which was very necessary for designing large flexible deploTo establish large deployable antenna reliably and accurately in space, a space visual-monitor system was researched. Using the system, the deployment of the antenna could be monitored real-time, and an analysis was made for dynamics on the deployment process, which was very necessary for designing large flexible deployable structures, detecting the anomalies and analyzing the possible reason. Based on the research on system task, the system project was introduced, including camera choice, visual information transfers way, image processing method and analog modulating scheme. Not only the key technology was researched, including image detection and recognizing for moving target and deploying dynamics analysis way, but also the validity of the technology by experiment was verified. The result of the experiment proved the space visual-monitor system including the key technology could complete the task of monitoring, measurement and analysis..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3304 (2015)
Analysis of accuracy in orbit predictions for space debris using semianalytic theory
Li Bin, Sang Jizhang, and Ning Jinsheng
For tens of thousands of Earth orbiting space debris, fast and accurate orbit determination and prediction information is essential for providing reliable collision warnings, and thus becomes an important subject in the space situational awareness(SSA). To overcome the problems of low computing efficiency using numericFor tens of thousands of Earth orbiting space debris, fast and accurate orbit determination and prediction information is essential for providing reliable collision warnings, and thus becomes an important subject in the space situational awareness(SSA). To overcome the problems of low computing efficiency using numerical integration methods and large orbit prediction errors with analytical theories, semianalytic satellite theory(SST) that could achieve the accuracy of numerical methods with the computing efficiency of analytic methods was developed. The semianalytic orbit integrator being developed using the multi-scale perturbation method at Wuhan University was discussed, together with its prediction performace. Orbits generated from the precise numerical integrator was used as the "true orbit" to compute the prediction error of the developed semianalytic integrator. Preliminary results show that, for space objects with Area-to-mass ratio 0.01 and orbit altitude 300 km, 2 km prediction accuracy for 1-day orbit prediction is achieved using the semianalytic orbit integrator, and the computation time was only 60 ms. For orbits higher than 1 000 km in altitude, the prediction errors were mostly less than 50 m, meeting the requirements for many space applications..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3310 (2015)
A new method of optical measurement-based spacecraft structure analysis
Teng Shuhua, Lu Min, Ma Yanxin, Yang Afeng, and Zhang Jun
Morphological structure analysis of space target is significant for space missions, such as space defense, space operations, et al. A space object structure analysis method was presented. First, a shape decomposition method was constructed by combining the minimum components criterion, the shortest internal length critMorphological structure analysis of space target is significant for space missions, such as space defense, space operations, et al. A space object structure analysis method was presented. First, a shape decomposition method was constructed by combining the minimum components criterion, the shortest internal length criterion and target skeleton. Based on which, the wavelet-moment was introduced into the analysis of satellite components, and the effective features were selected by the rough set reduction algorithm. At last, a multi-scale shape recognizer was presented by support vector machine, and thus the structure of space target was analyzed. Experiments on simulation data show that the proposed algorithm is efficient..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3317 (2015)
Application research on space debris laser ranging
Li Yuqiang, Li Rongwang, Li Zhulian, Zhai Dongsheng, Fu Honglin, and Xiong Yaoheng
Because of the existence of space debris, the space environment is getting worse, and the space activities safety is affected by space debris. Many countries have developed detection technique for space debris, and the space debris laser ranging is a new technology. Firstly, the development and the status of space debrBecause of the existence of space debris, the space environment is getting worse, and the space activities safety is affected by space debris. Many countries have developed detection technique for space debris, and the space debris laser ranging is a new technology. Firstly, the development and the status of space debris in the domestic and overseas were summarized in this paper. Secondly, space debris laser ranging echo was received successfully at Yunnan Observatories and the method of orbit determination with laser ranging date and angle date at single station was researched. The results of simulation calculation show that the precision of orbit determination by this method is better than that of by optical angle measurement. Finally, a method of space debris scale preliminary determination using the space debris laser ranging error was provided, and the feasibility of this method was verified by the experiments of ground target laser ranging and space debris laser ranging respectively, and this method is useful for further development of space debris scale determination..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3324 (2015)
Application of subdivision feature set of star pattern recognition method in astronomical navigation
Sun Jianming
A star pattern recognition method based on subdivisiom feature set was proposed in order to quickly and efficiently recognize star pattern and accurately complete celestial navigation task. Firstly, a database was built by star data, on which feature star database was established by triangulation. Then subdivision featA star pattern recognition method based on subdivisiom feature set was proposed in order to quickly and efficiently recognize star pattern and accurately complete celestial navigation task. Firstly, a database was built by star data, on which feature star database was established by triangulation. Then subdivision feature of star pattern could be compared, which will be recognized, with feature star database and implement star pattern recognition. By improving some similar methods like Hamming similarity and Euclid similarity, a new star pattern recognition method was put forward based on triangulation feature set, by which a very small possible star set could be found. This process can be repeated to obtain adjacent possible star set. In these two star sets, the nearest star between right ascension and declination was the one recognized. Experiments show that accuracy rate can reach more than 97% by using this method, and the star pattern recognition task can be completed accurately..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3330 (2015)
[in Chinese]
Surface contaminants detection method using brightness temperature spectroscopy
Liu Jiaxiang, Fang Yonghua, Cui Fangxiao, and Wu Jun
To solve the shortcomings of surface contamination detection, a new method based on brightness temperature spectroscopy was presented. Firstly, an infrared remote sensing spectrometer with high sensitivity was employed to acquire contamination′s spectrum in non-contact way. Taking advantage of the infrared source and tTo solve the shortcomings of surface contamination detection, a new method based on brightness temperature spectroscopy was presented. Firstly, an infrared remote sensing spectrometer with high sensitivity was employed to acquire contamination′s spectrum in non-contact way. Taking advantage of the infrared source and the background having the same highly emission characteristics as blackbody, contaminants spectral features in brightness temperature spectra directly could be extracted by applying Planck′s law. As this method does not require a previous measured background spectrum, it is very appropriate to be applied to "poisoned" accident sites. The principles of this method were discussed. Then this method and background subtraction method were employed to detect polydimethylsiloxane(PDMS), triethyl phosphate(TEP) on aluminum plate. The experiment results show that, the spectral features of contaminants extracted by brightness temperature spectroscopy are same as those acquired by background subtraction. It means that brightness temperature spectral features can be used to identify contaminants directly. Because there is no need to take background spectra before identification, this method could respond to chemical threats immediately and reliably, which make it a great application potential in surface contamination detection..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3469 (2015)
Accurate local region prediction by precise motion model in Kalman-particle filter
Xu Chao, Gao Min, and Yang Yao
Particle filter is widely used for visual tracking with superior performance in terms of accuracy and robustness, but it suffers from the heavy computational load, and the calculation complexity increases quickly with the state dimension and the number of particles. In this paper, the tracking problem was considered asParticle filter is widely used for visual tracking with superior performance in terms of accuracy and robustness, but it suffers from the heavy computational load, and the calculation complexity increases quickly with the state dimension and the number of particles. In this paper, the tracking problem was considered as a coarse-to-fine process to find the optimal state, thus, a hierarchical Kalman-particle filter (HKPF) with precise motion model, called improved hierarchical Kalman-particle filter (IHKPF), was proposed, in which Kalman filter with Jerk model was used to predict a local region around the estimation of global linear motion, and then particles were generated in the local region. The reason for introducing Jerk model was that the inadequate tracking performance of current models with the higher order derivating in the case of very highly maneuvering targets were not tracked therefore, Jerk was added. The high order state variable Jerk was applied in motion model of IHKPF. The HKPF, PF and proposed in the paper were used to compelete track experiment. The experimental results among the proposed algorithm HKPF and PF indicate that Jerk model provides higher accuracy prediction, resulting in well- behaved tracking in complex environment..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3475 (2015)
Design of high-speed image transmission system based on FPGA
Hao Xianpeng, Zhang Ranfeng, and Tao Hongjiang
The high-speed digital image transmission method for high speed camera is proposed, in order to overcome the current approach to long distance image transmission technology by LVDS. It can decrease the requirement of cable quality and system complexity, and be unnecessary of data relay. FPGA was used as the main controThe high-speed digital image transmission method for high speed camera is proposed, in order to overcome the current approach to long distance image transmission technology by LVDS. It can decrease the requirement of cable quality and system complexity, and be unnecessary of data relay. FPGA was used as the main controller. The received image data of LVDS format was changed into the signal of TTL format, and then was stored into the appointed location. Then the image data was transmitted by optical fiber after the high-speed serial data was gotten by RocketIO. The bit-error number was zero when 32 Gbit data is transmitted at the rate of 1.6 Gbps. The result shows that the method has the advantage of low bit-error rate, simple system design, excellent performance and convenient expansibility..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3483 (2015)
Image matching algorithm based on tensor subspace dimensionality reduction
Xiao Chuanmin, Shi Zelin, and Liu Yunpeng
An image matching algorithm based on tensor subspace dimensionality reduction was proposed to the questions of easily losing relationships between pixels and intensively computational problems using traditional vector subspace methods. The algorithm extracts tensor subspace by employing two-sided projection transformatAn image matching algorithm based on tensor subspace dimensionality reduction was proposed to the questions of easily losing relationships between pixels and intensively computational problems using traditional vector subspace methods. The algorithm extracts tensor subspace by employing two-sided projection transformation in edge images, reducing dimension of feature space and preserving the relationships between edge pixels. The algorithm measured the similarity between template and real-time image by calculating the correlation of dilated binary images. Experimental results on the standard face database and real IR images show that the new algorithm can improve the computational efficiency remarkably，and has a higher matching rate and matching precision than traditional vector subspace methods. The proposed algorithm can also be applied in cluttering and partially occluded circumstances..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3488 (2015)
Application of EMD and wavelet transform in low detectable targets detection
Gu Youlin, Ye Yingliu, Cao Guanghua, Hu Yihua, and Zhu Feng
Based on the situation of being difficult to detect low detectable targets with those conventional radar and infrared means, a novel algorithm of acquiring targets based on Empirical Mode Decomposition(EMD)and wavelet transform was proposed to tackle wind field disturbance detected by lidar. Through receiving the lidarBased on the situation of being difficult to detect low detectable targets with those conventional radar and infrared means, a novel algorithm of acquiring targets based on Empirical Mode Decomposition(EMD)and wavelet transform was proposed to tackle wind field disturbance detected by lidar. Through receiving the lidar echo signal reflected by atmosphere and the retrieval algorithm of wind speed, the wind field distribution in scanning area was acquired. The location of target was obtained based on EMD and wavelet transform. The experimental result shows that the target location is the radial distance of 1 250 m and the azimuth angle of 6° drawn by this algorithm is the same as the practical situation. Consequently, this novel means is practicable, which has an important significance in the detection of air low detectable target..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3494 (2015)
Dim air target detection based on radiation accumulation and space inversion
Ma Tianlei, Shi Zelin, Yin Jian, Xu Baoshu, and Liu Yunpeng
Background radiation noise interference is a difficult technical problem for dim signal detection. A dim target detection algorithm was proposed which can significantly improve signal-to-noise ratio(SNR) to achieve uniformly motion dim target detection successfully. Firstly, a coordinate space and a velocity space wereBackground radiation noise interference is a difficult technical problem for dim signal detection. A dim target detection algorithm was proposed which can significantly improve signal-to-noise ratio(SNR) to achieve uniformly motion dim target detection successfully. Firstly, a coordinate space and a velocity space were established. Then the original image sequence was stacked along different velocity vectors to acquire a new image sequence with SNR improved and the new image sequence forms an image space. Secondly, quasi-target points in the image space were detected by constant false-alarm ratio(CFAR) judging. Finally, velocity vectors and coordinate vectors of quasi-target points were mapped to the velocity space and the coordinate space respectively. As a result, two local peaks from the spaces will confirm true target points. Experiments of real images from actual IR imaging system show that proposed algorithm can improve SNR approximately up to n1/2 times of original image SNR, and the proposed algorithm is demonstrably superior to compared algorithms on detection probability and false alarm probability..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3500 (2015)
[in Chinese]
Progress of low level light video technology
Jin Weiqi, Tao Yu, Shi Feng, and Li Benqiang
As one of the key technologies to expand human eye′s night visual perception, low level light (LLL) night vision technology has wide application in military and civilian fields. With the development of digital image processing technology, LLL video devices not only improve the night vision image quality through the imaAs one of the key technologies to expand human eye′s night visual perception, low level light (LLL) night vision technology has wide application in military and civilian fields. With the development of digital image processing technology, LLL video devices not only improve the night vision image quality through the image processing, but also provide a broad space for image information fusion with the infrared thermal imaging and the improvement of nighttime target detection/recognition, scene understanding ability and so on, become one of the important directions of current night vision technology both at home and abroad. This paper reviews the development of LLL video devices, analyzes the characteristics and development trends of electronic vacuum + solid LLL video imaging devices(such as ICCD/ICMOS, Electron Bombardment EBCCD/EBCMOS, etc.), all solid-state LLL video imaging devices (such as electron multiplying EMCCD, Extreme Low-Light CMOS, etc.), analyzes and discusses the development of LLL night vision technology combined with PHOTONIS LYNX program..
Infrared and Laser Engineering
- Publication Date: Jan. 01, 1900
- Vol. 44, Issue 11, 3167 (2015)
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