2019 Vol. 40, No. 6

OE System and Engineering
Real-time infrared detection imaging simulation of aircraft considering influence of solar radiation
ZHANG Haochun, QU Boyan, JIN Liang
2019, 40(6): 929-936. doi: 10.5768/JAO201940.0601001
The imaging simulation for the infrared detection process of the aircraft contributes to the evaluation of the infrared stealth performance, thereby improving the anti-reconnaissance ability to deal with infrared detection. The aircraft infrared imaging simulation model was established, and the skin temperature and infrared radiation brightness for different flight attitudes, speeds and detection moments were solved. The results show that when the aircraft runs from low speed to high speed, the solar radiation conditions and the temperature distribution of the aerodynamic heating layer become the main factors affecting the imaging results. The modeling method and simulation results proposed have guiding significance for the stealth design of the aircraft, and provide a theoretical basis for the generation of real-time infrared imaging scenes.
Applications of SWIR lasers in photoelectric reconnaissance and counter-reconnaissance
YANG Aifen
2019, 40(6): 937-943. doi: 10.5768/JAO201940.0601002
Technique characteristics and current situations of four kinds of typical short-wavelength infrared(SWIR) lasers such as phosphorus semiconductor laser, Er-doped fiber laser, Er-doped solid-state laser and solid-state laser based on optical parametric oscillator were analyzed. Their applications in active photoelectric reconnaissance and counter-reconnaissance were given. In order to meet the requirements of military photoelectric system on reducing size and weight for laser devices, how to increase the output power/energy of lasers, such as semiconductor laser, fiber laser and Er-doped solid-state laser became the main development direction of SWIR lasers. Advantages of solid-state lasers based on optical parametric oscillator were still obvious at long-distance gated-viewing, flashlight imaging radar and laser damaging. The laser output energy and repetition frequency should be further improved.
Visual measurement method for seeker performance of guided weapon system
ZHANG Sanxi, ZHANG Weiguang, ZHANG Siqi, WU Haiying
2019, 40(6): 944-950. doi: 10.5768/JAO201940.0601003
Presently, indoor simulation and live ammunition firing are the main methods to evaluate the guidance performance of guided weapon system. However, due to the limitation of simulation conditions, there are some problems in indoor simulation such as inadequate description of target transient mechanism and low reliability of process reproduction. For live ammunition firing, the limited sample size, single environment settings and inconsistency of firing conditions limit the application. And this make it difficult to comprehensively assess the environment adaptability of weapon system. In order to solve this problem, an intermediate verification and assessment method was proposed for the real complex battlefield environment. In this work, a visual dynamic test platform for the guidance weapon system was constructed to obtain synchronization and real-time visualization of the seeker detection, recognition and tracking targets. The target information was extracted and the guidance performance was evaluated. Using this method, static and dynamic tracking tests could be carried out for actual target in shooting range environment. It can conduct integrated tests for seeker systems with different guidance modes such as laser, millimetre wave, television and infrared. It can provide direct data of targets and backgrounds for indoor simulation to improve simulation fidelity. It can also repeatedly check the key ability of guidance link and make up the insufficiency of firing test quantity of live ammunition. This would provide a new test and verification for weapon system development.
In-flight radiometric calibration of high spatial resolution satellite optical sensor using small targets
XU Weiwei, ZHANG Liming, LI Xin, SI Xiaolong, YANG Baoyun
2019, 40(6): 951-957. doi: 10.5768/JAO201940.0601004
Radiometric calibration is one of the key technologies for quantification of satellite remote sensing information. A calibration method for high resolution optical remote sensor was presented based on small targets. At the same time, the reflectance test on site was changed to accurate measurement in laboratory. It substituted the field actual determination to the assumption of aerosol scatter. The atmospheric transmittance and at-sensor radiance could be calculated by simplified radiometric transfer code. And the approach could isolate the digital number(DN) signal created by little targets from response produced by background radiance through system's point spread function PSF estimation, which reduced the background requirement and improved the absolute radiometric calibration accuracy. The experimental results show that the calibration uncertainty is less than 3% for high spatial resolution satellite. The difference of calibration coefficient is less than 3.65% compared with large test site or gray-scale targets method. The small target approach is expected to achieve full dynamic calibration and geometric calibration in the full spectrum range for high resolution satellite optical sensor.
Development and key technologies of small reconnaissance UGV
HOU Junzhan, ZHANG Weiguo, PANG Lan, YANG Guang, ZHANG Xiajiang, XU Xiaofeng, HUANG Weidong
2019, 40(6): 958-964. doi: 10.5768/JAO201940.0601005
Small reconnaissance unmanned ground vehicle(UGV)has good portability, concealing and flexibility, it has broad application prospects in military and civilian fields. Especially in the confined space and environment such as indoor or damaged buildings, the tasks of map building, person detection, weapon attack and others can be performed by it, which is a multifunctional unmanned combat platform. The research status and application situation of UGV at home and abroad was discussed, the technology level of this field at home and abroad was compared, and the domestic gap compared to foreign was analyzed. Finally, throught analyzing the application requirements, functional characteristics and development tendency, the key technical problems and research fields of the UGV were explored, and the development direction was obtained.
Analysis of influence factors on aberrations introduced by quadric conformal domes
ZHANG Yunqiang, CHANG Jun, PAN Guoqing
2019, 40(6): 965-972. doi: 10.5768/JAO201940.0601006
Traditional domes are hemispherical or parts of hemisphere, which generate high air resistance and are not conducive to the improvement of the flight speed for weapons. Therefore, based on the aerodynamic performance, the optical technique adopting conformal domes was proposed. The design method and surface expression of outer surfaces and inner surfaces on quadricconformal domes were described. The scanning imaging model of conformal domes was established in CODEV, and the effect law of different aspect ratios, edge slopes, aperture ratios and rotation cente on defocus aberration (Z4), astigmatism Z5), coma aberration (Z8) and spherical aberration (Z9) withr was studied by Zernike polynomial decomposition method. The results show that, the defocus aberration (Z4), astigmatism (Z5), coma aberration (Z8) and spherical aberration (Z9) introduced by quadricconformal domes expand with the increase of aspect ratios, edge slopes, aperture ratios, but they are not sensitive to the position of the rotation center on imaging systems. Therefore, the aspect ratios, edge slopes and aperture ratios should be decreased under the condition of meeting the weapon aerodynamic performance, while the position of the rotation center is mainly designed primarily based on the structural needs.
Design of tracking communication integrated receiving optical system
ZHAO Man, XIE Hongbo, CHEN Meng, YANG Lei
2019, 40(6): 973-979. doi: 10.5768/JAO201940.0601007
Aiming at the rapid change of relative position for the airborne platform and the gradual miniaturization and weight reduction of the airborne equipment, a coaxial dual-optical pathtracking communication integrated receiving optical system based on the method of large-field staring scanning was proposed with high frame rates complementary metal oxide semiconductor(CMOS) capture, fast steering mirror (FSM) adjustment tracking and avalanche photo diode (APD) communication. The working principle and scheme of the system were introduced. A set of verification system was designed, and the tracking and aiming performance of the system was optimized and analyzed. The tracking optical path field of view was up to ±175 mrad, and 90% of the energy spot diameter was less than 10 μm. The communication optical path field of view was up to ±13 mrad, and the root-mean-square(RMS) diameter was less than 3.5 μm. Taking into account the particularity of airborne application, the stray light characteristics and tolerance effects of the system were further analyzed. The results indicate that the scheme satisfies the requirements of high probability capture, high precision tracking, aiming and miniaturization, which has certain reference significance for airborne laser communication.
Design of optical system for large-field of view aerocamera
LIU Haiying, WANG Yue, WANG Ying, ZHU Haibin, SUN Hongyu, JIANG Yanming, ZHAO Hanqing
2019, 40(6): 980-986. doi: 10.5768/JAO201940.0601008
Aiming at the features of complex environment and needing high-resolution imaging in high-speed motion for aerocameras, a large-field of view(FOV) aerocamera optical system was designed. A double Gaussian symmetrical structure was adopted as the optical structure of this system, which expanded the camera's field angle by optical splicing with dual imaging modules, and the built-in focusing was achieved by adjusting the last lens. Throughcontrolling the three working modes of the ground objects reflector, the functions of vertical photograph, automatic focusing and forward image motion compensation for aerocameras were realized, respectively. Meanwhile, the image degradation caused by the changes in environmental conditions such as temperature, air pressure, and altitude during aerial photography was avoided to ensure the imaging quality throughout the FOV was not affected. In this design of the optical system, the full FOV without vignetting was realized, and the maximum distortion of the full FOV was less than 0.5‰. At 91 lp/mm, the modulation transfer function(MTF) was close to the diffraction limit, and the objective lens had the same imaging quality in the full FOV. The experimental results and aerial photography test prove that this optical system has the advantages of clear imaging, large FOV, high reliability, small size and light weight, which satisfies the requirements of the aerocameras to be clearly imaged in a relatively complex aviation environment.
Design of catadioptric infrared/laser compound seeker optical system
ZHOU Xiaobin, SUN Hao, YUAN Qi, LIU Zhaoqing, ZHANG Heng, WEN Jianghua, WU Yan
2019, 40(6): 987-992. doi: 10.5768/JAO201940.0601009
A common-aperture catadioptric optical system for uncooled long-wave infared (LWIR) and semi-active laser compound guidance was designed. In order to reduce the difficulty of parts manufacturing and assembly of the reflective system, the secondary mirror of Cassegrain system was simplified to a plane mirror, and the primary mirror adopted metal paraboloid.The lens size of eyepiece group was optimized to avoid internal occlusion of optical path, and the optical passive athermalization design of infrared channel was realized by using the reflection system primary image plane and infrared materials. What's more, the system spectral splitting efficiency and transmittance were improved by setting the beam splitting plate and laser narrow-band filter in the parallel optical path. Final design results show that at the characteristic frequency of infrared channel, the modulation transfer function (MTF) >0.2, the laser linear region is 2°, which meets the system index requirements.
Oe System and Engineering
Visual evaluation of seeker performance
HU Xiaoli, ZHANG Weiguang, ZHANG Siqi, ZHANG Sanxi, ZHANG Yulun, WANG Xiaohua
2019, 40(6): 993-997. doi: 10.5768/JAO201940.0601010
Laser and microwave guidance seekers donnot have the ability of visualization, therefore during the performance evaluation or bidding test in real environment, it is hard to get intuitive and accurate feedback and positioning for the cases whether the seeker succeeds in intercepting object or not, whether it is stable to track target regularly and some accompanying problems.The visual evaluation system designed could effectively solve the above problems.A tracking platform with simultaneous accompanying seeker was installed by a visible imaging system, which could image the seeker's searching and tracking process clearly and visualize its entire working process; at the same time, the image tracking system and image storage system were used to save key performance parameters.After accomplishing tests, the seeker's output parameters and tracking performance were verified and processed so as to analyze and evaluate the performance parameters of seeker.Dynamic tracking and loading interference source tests verify that, this method could synchronously follow the movement of the invisible seeker by using visual system to achieve the purpose of qualitative observation and quantitative analysis of the seeker tracking process. It could not only overcome the inaccuracy of indoor environment, but also provide a more economical and feasible research means for the performance evaluation of seeker.
Design of cooled MWIR continuous zooming optical system with high zoom ratio
HAN Xing, RUI Tao, YU Shuangshuang, ZHANG Zhen, ZHANG Chenzhong
2019, 40(6): 998-1003. doi: 10.5768/JAO201940.0601011
By using the mechanical compensation method, a two-component continuous zooming optical system model was established. Under the guidance of this model, a high zoom ratio continuous zooming optical system with tridimensional distribution was designed for the cooled focal plane array detector with mid-wave infared (MWIR) of 640×512 and pixel size of 15 μm. The working wave band of the system was 3.5 μm~4.8 μm, the focal range covered 30 mm to 500 mm, and the working temperature range covered -40℃~+60℃. In the zooming process, the F number was fixed at 4, and with 100% cold diaphragm effect. In the design process, the cold reflection of the system was analyzed in detail, and the cam curve wasdesigned optimally. The design results show that in the 0.8 field of view(FOV), the optical modulation transfer function(MTF) in whole temperature range is greater than 0.25 at 33 lp/mm and greater than 0.4 at 25 lp/mm. And in the full FOV tolerance, the MTF is greater than 0.13 at 33 lp/mm. This system has the advantages of smooth zooming track, excellent cold reflection suppression characteristics, good imaging quality and good environmental adaptability.
Design of missile target angle measurement path based on laser spot time-sharing method
CHEN Wenjian, SUN Weiping, DING Tianbao, LEI Junjie, DUAN Yuanyuan, LI Gang, HAN Yaofeng
2019, 40(6): 1004-1007. doi: 10.5768/JAO201940.0601012
A technical approach to measuring angle of multiple missiles using photoelectric methods was proposed. A semiconductor laser was mounted on the tail of missile to form a large width light source for angle tracing. It fired a pulsed laser array which was capable of penetrating plumes to the ground. When the guidance camera tracked the target, it also acquired the laser from the tracer, and calculated the angle between the spot and the target to complete the continuous measurement of the missile's angle, which was uploaded to the missile to form a closed-loop guidance. By timing control, the glow of the tracer and the exposure of the camera were synchronous. In each exposure period, light spots of only one missile could be received and the sequence pictures of each missile and target could be got, which supported the independent guidance of missiles through the marshalling of the camera video pictures. Test results show that the transmission distance reaches 9 000 m with the PM2.5 exponent of 120, the switching of 100 Hz dual light source can be realized and the encoding accuracy reaches 1 μs. This mode can satisfy the discrimination of detection ranges and missiles.
Attack effectiveness evaluation based on infrared image
GU Jie, QIU Jie, CAO Yitao, QIU Yafeng
2019, 40(6): 1008-1014. doi: 10.5768/JAO201940.0601013
The development of a noval intelligent and modular automatic gun tower system is of great significance to protect national territorial sovereignty. Aiming at the problem that the existing attack effectiveness evaluation systems of gun tower are too complicated and do not possess good real-time performance, the short-range and long-range attack effectiveness evaluation criteria based on infrared image is proposed. And the long-range attack effectiveness evaluation criteria is verified by digital experiments through computer programming. This criterion establishes a digital model based on the influence of various factors, combines them to calculate the probability value that the target groups are loss of combat capability, and finally converts the probability value into the corresponding attack effectiveness evaluation value. The digital experiments for the target group of three people show that, the combat effectiveness evaluation value are 24.8, 20.3, and 4.6 respectively under the loss of combat capability with 0, 1, and 2 person, which meet the long-range combat effectiveness evaluation criteria, and has theoretical research significance and engineering application value for realizing automatic strike.
Integrated network system of multi-photoelectric reconnaissance equipment
ZHAO Juncheng, LIU Jianping
2019, 40(6): 1015-1021. doi: 10.5768/JAO201940.0601014
In view of the shortcomings on single photoelectric reconnaissance equipment, such as small reconnaissance range and single tracking target, an integrated system using array photoelectric reconnaissance technology was designed, and the scheme of station distribution networking was proposed. The 5×6 array was used to arrange stations and networking, the warning line was extended forward and the reconnaissance area was enlarged. From the front zone to the central defense target, an orderly and relay detection was carried out and the combined tracking was formed. At the same time, the scheme design of station spacing was studied, and the most reasonable station spacing was got. By using the track of each unit in the coverage area of integrated photoelectric networking, the complete and continuous track of target could be obtained, and the accurate target state as well as the attribute estimation could be obtained by using the information fusion technology, which improved the detection probability of target. Finally, the calculation of coverage density analysis and target detection probability was completed. When the probability of target detection by a single photoelectric reconnaissance device is 90%, the comprehensive target detection probability in the coverage area of the whole system network can be increased to 97.472% by reasonable station distribution. The results show that the photoelectric networking technology can greatly enhance the target detection and tracking ability.
Space-time characteristics of aero-optical effect around conformal turrets
LU Daju, ZHANG Kai, DONG Hang, XU Ming, SU Hua
2019, 40(6): 1022-1032. doi: 10.5768/JAO201940.0601015
This study simulated the aero-optical effect of beams with different projection directions around conformal turrets with different radii(400 mm and 2 000 mm). The Mach number was fixed, and the Reynolds number remained similar in all cases. The space-time characteristic of beam quality factor and beam tilt angle caused by the aero-optical effect was comprehensively studied. The aero-optical effect was mainly determined based on the mean flow effect, and the characteristic frequency of the mean flow effect was determined based on that of the flow around the turret. The spatial characteristic of the aero-optical effect was accurately reproduced in the reduced-scale experiments; however, the temporal characteristic was poorly simulated. It is pointed out that the wavefront distortion statistics and fluctuation values caused by aero-optical effect aero-optical effect appear to be minimized at a projection direction of 40° zenith in the forward direction, and the increase of projection radius can result in fast increaseing of the mean flow effect while maintaining the turbulent effect almost constant.
Vision enhancement system research for military vehicle drivers based onuncooled infrared detection technology
LU Wei, DONG Jinliang, ZHANG Ping, SHEN Yu, YAN Wei, JI Zhongjie, MENG Xiangjian, LIN Ling, XU Aidong, ZHOU Zhihui
2019, 40(6): 1033-1038. doi: 10.5768/JAO201940.0601016
In order to improve the environmental awareness of military vehicle drivers, especially in the night or in different weather conditions such as smoke, fog, rain, snow, etc., as well as to provide more effective means of observation and increase long-distance target recognition ability and driving safety, new requirements of vision enhancement system for military vehicle drivers were proposed, which referred to efficient, flexible and precise. The vision enhancement system for military vehicle drivers based on uncooled infrared detection technology is a kind of equipment that can effectively support the whole-day and all-weather combat of the troops. It not only enhances the hidden traffic ability of the vehicle at night, but also effectively guarantees the all-weather maneuverability of the mechanized units. By studying the imaging principle of uncooled infrared detection technology, a modular, small-sized, low-power, high-reliability vision enhancement system for military vehicle drivers was designed, which was conducive to meeting the growing demand for army equipment. The functional modules include an infrared detector module, a signal processing module, an image processing module, an electronic image stabilization module, a pedestrian recognition module, a video recording module, a control module and a display module, in which they are relatively independent.
Analysis on effect of platform rotation on SAR imaging
XU Hui, SUN Yingqin, AN Guangrui, Zhang Yijun
2019, 40(6): 1039-1044. doi: 10.5768/JAO201940.0601017
The effects of platform rotation in three directions, yaw, pitch and roll, on synthetic aperture radar(SAR) imaging were analyzed. The platform rotation model was built, the analyses were conducted into three aspects: the change of the radar radiation area, the amplitude modulation and the phase modulation of the echo, and the effects of platform rotation on the imaging width and azimuth focusing were analyzed quantitatively.Simulation results show that platform rotation reduces the imaging width and leads to azimuth defocusing, so as to change the target azimuth position, which can provide guidelines for SAR system design and algorithm development.
Oe Information Acquisition and Processing
Study on metasurfaces image display technology
DAI Qi, FU Rao, DENG Liangui, LI Jiaxin, ZHENG Guoxing
2019, 40(6): 1045-1049. doi: 10.5768/JAO201940.0602001
A method for storing and displaying ultra-high resolution grayscale images based on metasurfaces was proposed. Combining the polarization splitting characteristics of the metal nanobricks arrays with Malus's law, the grayscale information of the image was encoded into the arrangement of nanobricks' orientation angles, thereby realizing accurate and continuous grayscale modulation. Experimental results show that a high fidelity grayscale image can be observed at the near-field of the metasurface with a high resolution of 90 714 ppi. This design method of image processing technology based on metasurfaces, which has the advantages of small volume, light weight, compact structure, and easy integration, is simple and flexible. Therefore, the proposed method indicates the potential in high-density optical information storage, high-end product anti-counterfeiting, information encryption and many other fields.
Research status and key issues of optical image camouflage effectiveness evaluation
GAN Yuanying, LIU Chuntong, LI Hongcai, MA Shixin
2019, 40(6): 1050-1058. doi: 10.5768/JAO201940.0602002
Evaluation of camouflage effectiveness based on optical image analysis has an important guiding significance to improve the survivability of main battle equipment in the battlefield, and it is one of the hot issues in the field of military defense. To facilitate researchers in related fields, the evaluation methods and research progress of optical camouflage effect are introduced briefly, such as conventional method, neural network evaluation model, human visual attention mechanism model and multi-attribute decision model. Then the basic ideas and applications of typical evaluation methods are expounded. After that, the characteristics and deficiencies of different models and the problems faced by the evaluation of optical camouflage effects are analyzed. On this basis, it is pointed out that the acquisition of training samples, the adaptability of model parameters and the timeliness of motion target camouflage evaluation are the research focuses of future camouflage effect evaluation.
Nonlinear unmixing of hyperspectral images based on double-bird flock optimization
WENG Xuhui, LEI Wuhu, REN Xiaodong
2019, 40(6): 1059-1066. doi: 10.5768/JAO201940.0602003
Aiming at the characteristics of nonlinear mixing on end-member materials in hyperspectral image pixels, a nonlinear unmixing algorithm of hyperspectral images based on double-bird flock optimization was proposed referring to the phenomenon of biological swarm intelligence. In order to further improve the accuracy of nonlinear unmixing algorithm, the optimal solution of the nonlinear problem was obtained by simulating the behaviors of foraging, vigilance and flight in the bird flock. The algorithm alternately updated the optimal solution of the objective function and the nonlinear model parameters through iteration optimization of double-bird flocks, and finally obtained the optimal estimation of the end-member abundance on hyperspectral images. The experimental results of simulated data and actual spectral data show that the double-bird flock optimization algorithm iteration converges and can overcome the local minimum problem.Compared with similar algorithms, the three indices of abundance reconstruction error, average spectral angular distance and pixel reconstruction error of the algorithm are smaller, which shows that the proposed algorithm has high resolution of unmixing, good reconstruction effect of pixel, and can effectively improve the nonlinear unmixing accuracy of hyperspectral images.
Embedded GPU-based parallel optimization for moving objects segmentation algorithm
ZHANG Gang, MA Zhenhuan, LEI Tao, CUI Yi, ZHANG Sanxi
2019, 40(6): 1067-1076. doi: 10.5768/JAO201940.0602004
In optoelectronic surveillance systems, the pixel base adaptive segmenter (PBAS) algorithm, which is widely used in moving objects segmentation, is hard to meet the requirements of real-time applications due to its calculating complication and a large amount of computing parameters. With its pixel-level parallelism, deploying PBAS on top of graphic processing unit (GPU) is promising. This paper implements real-time optimization of PBAS on embedded GPU platform-Jetson TX2, employing methods of data storage architecture, shared memory utilization and random number generation. Experimental results show that the parallel optimization method can achieve 132 fps when processing 480×320 pixel medium-wave infrared video sequences, thus meets the real-time processing need.
Research on automatic classification of point cloud scanned by lidar during power-line patrol
YOU Anqing, PAN Xudong, ZHAO Ping, PAN Wenwu
2019, 40(6): 1077-1083. doi: 10.5768/JAO201940.0602005
For 3D laser point cloud scanned by lidar on power lines, an automatic method was designed to divide point cloud into 3 types: point of lines, point of pylons, and point of ground objects. This process can lay essential foundation for spatial distance check in power transmission system. The core of the method is making full use of global statistical features of point cloud instead of local features, thereby maximally prevented limitation of the algorithm. According to dozens of practical tests from State Grids, the automation and universality of this method are satisfactory, which largely reduce the work usually laborious in traditional classification with commercial softwares by half-automatical interactive process, and shorten the average processing time from about 1 hour to several seconds, greatly improve working efficiency and userexperience.
Optical Metrology and Measurement
Research on error compensation method for infrared temperature measurement under laser irradiation
SU Chengzhi, YAN Chun, WANG Fei, ZHANG Chengshuang, BAO Yanling, RUAN Yingbo
2019, 40(6): 1084-1090. doi: 10.5768/JAO201940.0603001
In order to improve the infrared temperature measurement accuracy at the heating point under laser irradiation, a multivariate temperature compensation model was established, and the relationships among measurement distance, measurement angle and measurement accuracy were analyzed. A binary variable compensation model for measuring distance and angle was established by using single variable method and orthogonal variable method, and the error compensation model was verified by experiments. The results show that the compensation model can match the actual measurement results well. The measured error after compensation is ±1.25%, which improves the measurement accuracy by 64.25% compared with that before compensation. This verifies the correctness of the compensation model, which can provide theoretical guidance for infrared measurement of heating point temperature under laser irradiation.
Space non-cooperative target spin rate measurement method and experiment
WANG Li, GU Yingying, GUO Shaogang, LI Tao, CHU Yi
2019, 40(6): 1091-1096. doi: 10.5768/JAO201940.0603002
In order to measure the motion state of the unstable and fast-swirl non-cooperative target, a measurement method based on sequence images of monocular camera was proposed. First, the measurement principle was derived and proved according to the projection geometry of the target and the detector. Then, considering the characteristics of the space lighting environment, an image processing method based on maximally stable extremal regions(MSER) features was proposed to extract the projection angle. Moreover, according to the multi-frame sequence projection angle value, the spin rate of the non-cooperative target was calculated by setting a reasonable polynomial fitting model. Finally, the effectiveness and measurement accuracy of the proposed method were further verified by on-orbit data. Experimental results show that, for the 60°/s fast-spinning non-cooperative target, a monocular camera with 1Hz frame rate is used to observe the target in 150 seconds, the mean measured value by this method is 60.07° and the standard deviation is 0.05°/s. Therefore, a stable, reliable and highly precision spatial non-cooperative target motion state measurement is achieved.
Research on deformation measurement method of high-speed moving target based on linear CCD pixel number extraction
XU Chengqiang, WANG Yingbo, CAO Jie, HAO Qun, YUAN Shizhu, JIANG Yahui
2019, 40(6): 1097-1102. doi: 10.5768/JAO201940.0603003
Aiming at the shortcomings of traditional optical imaging measurement methods, such as low frame frequency, blurred image quality and difficulty in meeting the requirements of high-precision measurement of target deformation, a new method of high-speed target deformation measurement based on linear CCD pixel number extraction was proposed.This method takes advantages of the linear charge-coupled device (CCD), such as high resolution and high frame frequency. The pixel extraction method for obtaining the target number N of pixels was used by extracting the line array CCD output target intensity-the maximum point of the slope change rate of the pixel curve. At the same time, the digital micromirror device(DMD) was utilized to simulate the high-speed moving target deformation process, combined with the linear CCD pixel number extraction based high-speed moving target deformation measurement method to conduct experimental verification. The experimental results show that the deformation of the high-speed moving target with V=450 km/h can be measured by the method proposed, which can meet the requirements for the target deformation measurement deviation less than 0.3 mm, the standard deviation less than 0.5 mm, and the lowest relative error of 0.01%. The accurate measurement of the high-speed moving target shape variable is realized, which lays a foundation for high-speed wear test, high-temperature deformation test and high-pressure shape test.
Noise equivalent radiance calibration system for infrared Fourier spectrometer at low-temperature and vacuum environment
HANG Sijia, XIA Maopeng, LI Jianjun, ZHENG Xiaobing, LEI Zhenggang
2019, 40(6): 1103-1108. doi: 10.5768/JAO201940.0603004
The equivalent noise radiance (NESR) of infrared Fourier spectrometer is not only a reflection of its ultimate detection ability to infrared target signal, but also a core technical index of instrument. Limited by the current technical conditions in China, there is no relevant capability of calibration system testing and specification verification yet. Based on the standard transmission method of infrared radiation metering devices at home and abroad, a scheme of NESR high-precision testing device was proposed. The traceability chain of this device was put forward, its overall structure and optical path were also described, while a suppression system with low-temperature and vacuum background was designed. This designing scheme of radiation source on infrared integrating sphere with wide dynamic range, equivalent optical path and vacuum cryogenic environment were introduced in detail. The proposed technical solution provides a basic reference for NESR high-precision measurement, which also supports the condition of NESR quantity traceability for Fourier spectrometer in China.
Transient measurement on electric explosion of metal wire by nanosecond pulsed laser
WEI Yonghui, WANG Shiyu, WU Mengyao, CAI Defang, GUO Zhen
2019, 40(6): 1109-1114. doi: 10.5768/JAO201940.0603005
Electric explosion of metal wire is an effective way to obtain the nanometer-sized metal powder particles, the deductive procedure directly affects the size of the metal powder particles. Nanosecond pulsed laser was used to observe the transient state of the explosion process. And based on the laser interference fringes, the image of the explosive area with clear edge was obtained according to the interference of the fringes in the process of electric explosion. The three-dimensional distribution of the metal powder concentration at different moment was calculated according to the transmittance of laser passing through the explosive cloud. Measuring results show that, the diameter of metal wires expands from 0.3 mm to 4.7 mm by 0.5 μs after energization, and expands to 28 mm by 18 μs. The maximum concentration of particles decreases from 3×1021 /cm3 to 1.1×1020 /cm3. Throughout the expansion process, the particle concentration distribution presents the multiple ring belts along the radial direction.
Detection of performances and noise of APD detector module
LI Yongliang, YU Jianhui, ZHANG Jun
2019, 40(6): 1115-1119. doi: 10.5768/JAO201940.0603006
In order to realize the miniaturization of the detector module of visible light communication system, a 50 cm3 temperature-controlled avalanche photodiode (APD) detector module was designed and fabricated, and the stability, temperature control effect and noise characteristics of the module were tested. The results show that the average relative deviation of photocurrent measurement of APD detector module is 0.795%; the avalanche gain and responsivity of APD detector increase with the decrease of temperature; the change of the resistance of the APD detector affects the load resistor divider so that the measured value of the excess noise factor is much larger than the true value and increases as the incident light power increases. It can be concluded that increasing the reverse bias voltage in combination with lowering the temperature control temperature is more conducive to weak light signal detection; the load resistance in the detection circuit affects the noise characteristics of the APD detector.
Micro-objects measurement system based on structured light fringe projection
SHI Yaoqun, DENG Linjia, WANG Zhaoxu, FU Yanjun, ZHONG Kejun, GUAN Bingliang
2019, 40(6): 1120-1125. doi: 10.5768/JAO201940.0603007
In order to measure micro-objects by the method of structured light projection, a set of three-dimensional topography measurement system for micro-objects was built, and the field rangecould reach 1.8 cm×1.6 cm.This measurement system took advantage of the high-speed projection feature of Light Crafter 4 500 digital projection module, low distortion scaling feature of stereoscopic microscope, extended depth of field and low distortion imaging feature of telecentric lenses. First the phase shift fringes projected by Light Crafter 4 500 were scaled down with low distortion by stereoscopic microscope, then projected it to the surface of the measured object, and the camera equipped with telecentric lens synchronously recorded deformable fringes that were modulated by the object surface topography. The corresponding truncation phase diagram was calculated by using three-step phase shift method, and then the continuous phase distribution by phase-unwrapping algorithm based on reliable path tracking was also sought for. The three-dimensional surface topography of the measured object was reconstructed. The experiment successfully reconstructs the three-dimensional topography of micro-objects surface such as BGA chips, and the results show that the system measurement accuracy reaches 11 μm, as well as the effective depth measurement range of the system is 700 μm.
Optical Element and Fabricatio
Research status and development of liquid lens
GU Haipeng, HONG Huajie, FAN Jihong
2019, 40(6): 1126-1138. doi: 10.5768/JAO201940.0605001
At present, the equipment in the field of photoelectric reconnaissance develops lighter and smaller constantly, while the volume and weight of traditional zoom optical system cannot satisfy the load requirements of micro photoelectric reconnaissance platform. Therefore, the small unmanned aerial vehicle (UAV) and other reconnaissance platforms can only equip withprime lens, which limits the improvement of resolution, detection distance and reconnaissance ability. The liquid lens technology can adjust the focal length by using a single lens, which largely reduces the volume of the optical system, and has fast zoom response and wide zoom range. The optical system composed of liquid lens can fast zoom in a fixed small volume, which has broad application prospects in both military and civil fields. The theoretical basis and research methods of the predecessors were investigated and summarized. Firstly, five basic principles of liquid lens were briefly described, and their characteristics were analyzed respectively. Then, the research status of liquid lens at home and abroad were introduced. And finally, the merits and demerits of liquid lens, as well as its future development and research directions were indicated.
Review of microsphere optical microscopy for super-resolution imaging and metrology
XU Wei, YUAN Qun, GAO Zhishan, YU Haobiao, SUN Yifeng, QU Yi
2019, 40(6): 1139-1151. doi: 10.5768/JAO201940.0605002
Due to the diffraction limit, the greatest resolution of conventional optical microscopes is about half of the wavelength. Efforts to overcome the diffraction limit and to obtain higher imaging resolution have been hot researching spots of optical microscopy imaging field in recent years.Compared with other types of super-resolution microscopy imaging, the method based on microsphere optical microscopy is characterized by simple direct and label-free, etc. This paper briefly introduces the research progress of super-resolution microscopy imaging is, which combines microsphere with conventional optical microscopes by domestic and foreign teams, summarizes and compares from multiple aspects of microsphere lens parameters, imaging scheme, resolution, field and mechanism. Further, this paper elaborates the three-dimensional super-resolution metrology by combining microsphere lens with interference microscopy, is d as well as our research team work, described the optical paths in the types of Linnik and Mirau are, and analyzes the super-resolution measuring results are. Finally, it discusses the applications of the microsphere lens for super-resolution in microscopy imaging and interference metrology, and some of the future research works are prospected.
Recent advances of photoacoustic spectroscopy techniques for gases sensing
CAO Yuan, XIE Yingchao, WANG Ruifeng, LIU Kun, GAO Xiaoming, ZHANG Weijun
2019, 40(6): 1152-1159. doi: 10.5768/JAO201940.0605003
Photoacoustic spectroscopy has been an important branch of spectroscopy, which refers to a kind of spectral sensing technology that converts sample absorbed optical energy into acoustic detection wave through photoacoustic effect and realizes detection of sample composition and concentration analysis with acoustic sensor. In addition to high selectivity and high sensitivity of the spectrum absorption, photoacoustic spectroscopy offers several intrinsic attractive features, including signal only related to sample light absorption, free from scattered light, zero background and signal proportional to optical power, as well as measured with wavelength-independent acoustic transducers. More and more applications have been found in the fields of environmental monitoring, industrial process control and detection, medical diagnosis and hazardous chemicals detection in national defense. Besides the traditional resonant photoacoustic spectroscopy technology, there have been new techniques such as cantilever enhanced photoacoustic spectroscopy, quartz tuning fork enhanced photoacoustic spectroscopy and multi-channel photoacoustic spectroscopy. The recent advances of photoacoustic spectroscopy techniques for gases sensing are reviewed, and their application prospects and future development trends are analyzed.
Design of support structure for small caliber off-axis parabolic reflector based on finite element analysis
XING Minghui, LI Jianjun, ZHAI Wenchao, TANG Qi, ZHENG Xiaobing
2019, 40(6): 1160-1166. doi: 10.5768/JAO201940.0605004
In order to reduce the surface shape error of small caliber reflector in the complex environment and meet the requirements of the dynamic and static stiffness and the thermal stability, the appropriate space loading materials were selected and the lightweight design of the reflector was carried out. The flexible support component of the reflector which could be installed and adjusted was designed reasonably, and the finite element analysis of reflector component was obtained by using ANSYS. The results of analysis show that the first-order natural frequency of the component is 3 168.5 Hz; under the action of 1g gravity, the root-mean-square(RMS) value of the reflector surface shape error can reach 8.06 nm, and it can reach 5.58 nmunder the load of 10℃ temperature rise, . while under the coupled action of 1 g gravity and the load of 10℃ temperature rise, the RMS value can reach 11.05 nm.The maximum stress under the action of 10 g acceleration is 2.109 8 Mpa, and the maximum response stress of the weakest link under the action of simple harmonic excitation is 1.284 6 Mpa, all of which fully meet the design index requirements of the reflector component, verifying the rationality of the suppor structure design.
In situ detection and evaluation of surface defects for large-aperture optical elements
WANG Guilin, ZHU Junhui, LI Jiaxiang, LI Zhibin
2019, 40(6): 1167-1173. doi: 10.5768/JAO201940.0605005
If the technology is not properly controlled in the machining process of precision optical elements, although the distribution range of defects such as scratch and pitting is small, it has great influence on the performance of optical system and is very destructive. At present, the surface defect detectors are mainly used for off-line detection of planar or spherical optical elements. The optical machine tool was used as the motion platform, the method of scattering imaging was adopted in dark field, the uniform illumination system with multi-beam was designed, the recognition algorithms of fine features on surface defects were studied, and in-situ detection and evaluation of surface defects for large-aperture optical elements were achieved. Calibration results show that the width deviation of surface defect is 2.05% and the length deviation is 2.39%, which meet the index requirement. On this basis, automated in situdetection is carried out for Φ280 mm planar silicon mirror. The statistical data of different defects is given, and the problems of long non-machining time and locating error caused by multiple clamping in off-line detectionare solved.
Dynamic tuning color filters based on stretchable materials
FENG Yan, TIAN Nan, WANG Jicheng, SANG Tian
2019, 40(6): 1174-1180. doi: 10.5768/JAO201940.0605006
The dynamic tuning integrated optical devices possess a good application prospect in the fields of imaging and display. A noval dynamic tuning titanium oxide polymer micro-nano structure filter based on stretchable substrate was proposed. The surface of the structure could be fabricated by the electron beam evaporation deposition and lift-off technology.The finite-difference time-domain(FDTD) method was used to simulate and optimize the structure parameters, and the filtering effect and its physical laws were analyzed. The analysis results indicate that, by stretching the substrate, the designed filter structure can achieve full waveband filtering at the visible light waveband, and it also has ultra-high reflectivity, most of which is above 95%, and the maximum reaches 99.1%. This provides theoretical support for the experiment of fabricating dynamic tuning filter array by deposition and lift-off technology. Compared with the disadvantage that the device structure of static tuning filter cannot be changed once it is finalized, the dynamic tuning structure can still be adjusted in real time after the device is finalized.