Journals >Infrared and Laser Engineering
Contents
2020
Volume: 49 Issue 7
34 Article(s)
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Image Processing
Application of trust region method in infrared image sequence processing
In the process of collecting thermal images of infrared nondestructive testing (NDT) with light source as the excitation, due to the influence of uneven heating, environmental radiation and other factors, the collected thermal image sequence has problems such as high background noise, low contrast and poor display effeIn the process of collecting thermal images of infrared nondestructive testing (NDT) with light source as the excitation, due to the influence of uneven heating, environmental radiation and other factors, the collected thermal image sequence has problems such as high background noise, low contrast and poor display effect of defects, which are easy to cause the omission of defects. In order to improve the defect detection rate, infrared thermal image sequence processing technology based on Trust Region Reflective (TRR) algorithm was proposed. Firstly, the background noise surface with uneven heating was fitted by TRR algorithm, and the background surface obtained by fitting was subtracted from the original thermal images to remove the background noise caused by uneven heating. Then, Principal Component Analysis (PCA) algorithm was used to extract the defect feature information of the thermal image sequence after removing the background, so as to further improve the signal-to-noise ratio of the infrared thermal wave images. Finally, the defect region was segmented by region-growing algorithm. The experimental results show that a combination of these algorithms can effectively improve the signal-to-noise ratio of the infrared thermal image, thus improve the defect detection rate..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20190505 (2020)
Invited Paper
An upgraded combined atmospheric radiative transfer CART2(Invited)
Using the HITRAN2016 database, a new database of atmospheric molecular absorption coefficients was obtained by recalculating and fitting, which was applied to the upgraded 2nd edition of the Combined Atmospheric Radiative Transfer (CART2). A CART2P1 program module with a spectral resolution of 0.1 cm-1 has been added. Using the HITRAN2016 database, a new database of atmospheric molecular absorption coefficients was obtained by recalculating and fitting, which was applied to the upgraded 2nd edition of the Combined Atmospheric Radiative Transfer (CART2). A CART2P1 program module with a spectral resolution of 0.1 cm-1 has been added. Compared to CART 1.0, atmospheric molecular absorption takes into account weaker molecular absorption lines. The comparisons to LBLRTM between the calculated results of MODTRAN5 and CART showed that CART2 can accurately simulate the absorption of atmospheric molecules; the calculated results agree well with the real measured ground-based infrared high-resolution solar spectrum. The atmospheric transmittance and environmental background radiation calculated by CART2 with a finer 0.1 cm-1 spectral resolution can distinguish discrete atmospheric molecular absorption lines, which can be applied to radiative transfer calculations for medium-to-high spectral resolution optical engineering or some laser engineering..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20201024 (2020)
Optical Communication and Sensing
Validity of beam propagation characteristics through oceanic turbulence simulated by phase screen method
Chaojun Niu, Xiaobin Wang, Fang Lu, and Xiang’e Han
Oceanic turbulence is an important factor to restrict the application of underwater optical communication. Phase screen method is a simple and effective way to simulate the propagation process of complex beams through turbulence. The constraints of parameter setting for phase screen simulated oceanic turbulence based oOceanic turbulence is an important factor to restrict the application of underwater optical communication. Phase screen method is a simple and effective way to simulate the propagation process of complex beams through turbulence. The constraints of parameter setting for phase screen simulated oceanic turbulence based on the sampling principle and turbulence effects were firstly discussed here. Furthermore, the theoretical expressions of propagation characteristics of Gaussian beam through oceanic turbulence from weak to strong fluctuation regime were derived. Our goal in this research was to testify the validity of phase screen method in oceanic turbulence by comparison of major statistical characteristics of Gaussian beam propagating in oceanic turbulence simulated by phase screen method and the theoretical expressions derived. Results show good match between simulation results and theory formulas for long exposure beam radius and centroid displacement under different turbulence conditions, as well as the scintillation index under weak fluctuation regime. However, results show significant mismatch between numerically estimated and theoretically predicted values for the on-axis scintillation index in strong fluctuation regime..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190452 (2020)
Optical Design
Structural design optimization of space gravitational wave telescope primary mirror system
The structure and supporting components of the primary mirror system of space gravitational wave telescope were designed and optimized. The side three-point support was used to restrain the mirror body with the primary mirror, and the selection and layout of support points were studied. The mirror adopted a semi-enclosThe structure and supporting components of the primary mirror system of space gravitational wave telescope were designed and optimized. The side three-point support was used to restrain the mirror body with the primary mirror, and the selection and layout of support points were studied. The mirror adopted a semi-enclosed structure with back drill holes, which can achieve large bending stiffness. The lightweight structure of the mirror was optimized by finite element calculation combined with multi-objective genetic algorithm. The lightweight ratio of the mirror structure reached 74% without reducing the surface accuracy. An adjustable bi-axis bipod flexure hinge structure composed of two non-barrier series flexibility elements was designed, which can compensate the surface error of the mirror. The mathematical model of the flexible hinge parallel mechanism acting on the mirror was established, and the parameters were analyzed based on MATLAB. The parameters were corrected by finite element method. Finally, the analysis of mirror shape under space thermal load was carried out. The results show that the error of mirror shape is better than λ/60, which meets the design requirements..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20190469 (2020)
Design of zoom fish-eye lens systems
The zoom fish-eye lens had the characteristics of much larger field-of-view angle, much larger relative aperture, and much larger anti-far ratio. In the work described in this paper, the initial structure of a fish-eye lens with fixed focal length was firstly designed using the theory of a plane symmetric optical systeThe zoom fish-eye lens had the characteristics of much larger field-of-view angle, much larger relative aperture, and much larger anti-far ratio. In the work described in this paper, the initial structure of a fish-eye lens with fixed focal length was firstly designed using the theory of a plane symmetric optical system. And then the initial structure components of the fish-eye lens were divided into two groups, the former-group and the rear-group, and then the entire zoom fish-eye lens system was optimized using Gaussian optical theory. Finally, a zoom fish-eye lens system with good imaging quality was obtained. This fish-eye lens system had a field-of-view angle of 180° with an 8 mm short focal length and a field-of-view angle of 90° with a 16 mm long focal length. Its relative aperture was 1/3.5. The design results show that the modulation transfer function of this zoom lens system at different focal lengths is no less than 0.45 when the spatial frequency is 50 lp/mm. This zoom fish-eye photographic objective lens had higher imaging quality than other zoom fish-eye lenses..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20190519 (2020)
Optical Devices
Radiation effects of 0.18 μm CMOS APS by proton irradiation
Complementary metal-oxide-semiconductor (CMOS) image sensors can easily be susceptible to proton irradiation in space applications. A proton irradiation experiment of a domestic commercial CIS was conducted on the ground, and the cumulative radiation effect and single event effect were studied by using offline and onliComplementary metal-oxide-semiconductor (CMOS) image sensors can easily be susceptible to proton irradiation in space applications. A proton irradiation experiment of a domestic commercial CIS was conducted on the ground, and the cumulative radiation effect and single event effect were studied by using offline and online image acquisition methods. The proton-induced cumulative radiation effects were studied by analyzing the dark signal degradation after irradiation, and histogram and generation mechanism of dark signals were analyzed from the aspects of total dose and displacement damage. Online testing results show that proton-induced single event transients in active pixel array include transient bright spot, transient bright cluster, and transient bright line. The interaction mechanism of proton and CIS was analyzed to discuss the different single event transient phenomena. No single event latch-up and single event function interruption in the peripheral circuits of the CIS was observed in the experiments..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20190433 (2020)
Optical Fabricaion
Processing technology of cutting ZnS crystal
Shijie Li, Chao Xu, Yuetian Huang, Shouyi Wang, and Weiguo Liu
With the wide application of ZnS crystal optical elements in infrared optical system, the surface quality of ZnS crystal optical elements is more and more demanding, but due to the brittleness of the material, it is difficult to obtain high quality surface roughness. In order to obtain high quality surface of ZnS crystWith the wide application of ZnS crystal optical elements in infrared optical system, the surface quality of ZnS crystal optical elements is more and more demanding, but due to the brittleness of the material, it is difficult to obtain high quality surface roughness. In order to obtain high quality surface of ZnS crystal, the principle of cutting and fly-cutting based on single point diamond lathe was introduced, as well as the factors affecting surface roughness. And then the influence of different parameters of diamond tool and different processing parameters on the surface roughness of ZnS flat element was studied by single variable method through process experiment. The quality of the machined surface was tested by microscope and white light interferometer, and the processing parameters were optimized by feedback. Finally, based on the optimal processing parameters, high quality ZnS flat optical elements with surface roughnessSa of about 1 nm were obtained in the both different methods. The results provide technical support for the development of high quality optical elements of ZnS crystal and have good engineering application value..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190567 (2020)
Removal of the single point diamond turning marks by spiral sine trace bonnet polishing process
Peng Wang, Hao Zhang, Yapeng Jia, Kun Yang, and Weihao Li
Single point diamond turing (SPDT) technology has been widely used in the high precision optical surface processing field. However, the micro-nano texture which is mainly composed of turning marks remain on the turned surface will affect performance of optical systems. Therefore, it’s necessary to remove the turning maSingle point diamond turing (SPDT) technology has been widely used in the high precision optical surface processing field. However, the micro-nano texture which is mainly composed of turning marks remain on the turned surface will affect performance of optical systems. Therefore, it’s necessary to remove the turning marks for improving the surface quality. Removal of the single point diamond turning marks was studied in the paper. It was found that the removal efficiency was highest when the polishing direction was perpendicular to the turning marks. A new polishing trace called spiral sine trace was presented based on the finding. The design principle was introduced in detail. Contrast experiment of different polishing tracks consisting of spiral sine trace, spiral trace and raster trace utilizing bonnet polishing was carried out. Result shows that the improvement effect of micro-nano texture in spiral sine trace was obviously superior to two other kinds of trace. A germanium aspherical surface manufactured by SPDT was smoothed by spiral sine bonnet polishing. The results shows that the roughness of surface Ra reduce from 1.28 nm to 0.4 nm before and after polishing, the regular turning marks transform to random micro-nano texture, and above all, the surface figure accuracy isn’t damaged during the smoothing process..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20200212 (2020)
Special Issue on Infrared Extinction Technology
Research progress on artificially prepared infrared extinction materials and their extinction properties(Invited)
As an important means to weaken the performance of infrared imaging equipments or systems, artificially prepared infrared extinction materials have become the research object of many countries, and have achieved staged research results. The research status of artificially prepared infrared extinction materials is introAs an important means to weaken the performance of infrared imaging equipments or systems, artificially prepared infrared extinction materials have become the research object of many countries, and have achieved staged research results. The research status of artificially prepared infrared extinction materials is introduced from metal materials, expanded graphite, nano-materials, water-based foam, biomaterials and composite materials. The particle aggregation models of extinction materials such as particle and cluster, cluster and cluster are described. Several typical extinction calculation methods such as Mie scattering method, discrete dipole approximation method, T matrix method, and finite-difference time-domain method are introduced. According to the analysis, the infrared extinction materials prepared manually in the future will develop in the direction of long duration, low cost, various forms of release, environmental protection and non-toxic..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20201018 (2020)
Development of anti-infrared smoke material and its extinction performance(Invited)
Xuanyu Wang
In order to promote the research and application transformation of anti-infrared smoke screen materials, the research status, main problems and development trend of the materials were systematically analyzed from the material development and research on extinction performance. The results show that the research of carbIn order to promote the research and application transformation of anti-infrared smoke screen materials, the research status, main problems and development trend of the materials were systematically analyzed from the material development and research on extinction performance. The results show that the research of carbon black and red phosphorus based hot smoke materials mainly focus on the improvement of the formula. The cold smoke materials, such as layered super-molecular, ultrafine ceramic powder, nano powder and biomaterials, have made remarkable achievements in structural design and synthesis technology. At present, there are some problems in the research, such as the lack of environment-friendly anti-infrared smoke screen materials, the difficulty of extinction theory innovation and so on. In the future, low cost-effectiveness ratio and environment-friendly anti-infrared smoke materials will become the development focus in this field..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20201019 (2020)
Preparation of carbon coated ferromagnetic composite materials by one-pot and IR extinction performance(Invited)
Lixia Bao, Xiaojing Qiao, and Ming Yang
Carbon coated ferrite precursor was prepared by one-pot hydrothermal method, which was calcined at 950 ℃ with N2 protection to obtain carbon coated ferromagnet composite materials. The morphology and composition of the materials were analyzed by XRD, FT-IR and SEM, and the effects of reaction time, the ratio of starch Carbon coated ferrite precursor was prepared by one-pot hydrothermal method, which was calcined at 950 ℃ with N2 protection to obtain carbon coated ferromagnet composite materials. The morphology and composition of the materials were analyzed by XRD, FT-IR and SEM, and the effects of reaction time, the ratio of starch and glucose on the morphology and IR extinction of the composite were studied. The IR extinction coefficients of materials in the range of 2.5-25 μm were measured and calculated by KBr method of FT-IR. The results show that the samples have good morphology and extinction performance, that were prepared under the conditions of reaction time of 20 h and 18 h and the ratio of starch and glucose of 9:3 and 6:10. In the range of 4-10 μm, the extinction coefficient of sample 5 and 7 is greater than 0.3 m2/g and the maximum is 0.37 m2/g..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20201020 (2020)
Infrared extinction properties of typical aerosol particles(Invited)
Graphite and aluminum powders are typical aerosol particles whose infrared (IR) extinction properties are important to the IR obscuring performances of the smoke ammunitions containing these powders. Mass extinction coefficients (MECs) of the two materials with different sizes are measured in a smoke chamber. The relatGraphite and aluminum powders are typical aerosol particles whose infrared (IR) extinction properties are important to the IR obscuring performances of the smoke ammunitions containing these powders. Mass extinction coefficients (MECs) of the two materials with different sizes are measured in a smoke chamber. The relationship between the powder size and the IR extinction property is analyzed, with the difference between their extinction properties being discussed. Moreover, test accuracy is studied at different temperatures of the target and the background. The results show that the IR extinction property gets better as the size of the graphite powder decreases. Due to its better dispersivity, larger radius-thickness ratio and larger IR refractive index, aluminum powder shows better extinction properties than graphite powder of the same size. The IR MECs of aluminum powder (1 000 meshes) are respectively 1.78 m2/g (3.7- 4.8 μm) and 2.01 m2/g(7.5-14 μm), with those of graphite powder of the same size being 1.02 m2/g and 1.01 m2/g respectively. In addition, test results are found to be closely related to the initial temperatures of the target and the background, showing the necessity of appropriate settings of the temperature..
Infrared and Laser Engineering
- Publication Date: Jul. 25, 2020
- Vol. 49, Issue 7, 20201021 (2020)
Analysis of extinction characteristics of sandstorm to infrared radiation(Invited)
Hongxia Wang, Honghui Sun, and Qinghua Zhang
The extinction and attenuation characteristics of seven modes of sandstorm in China for 0.86 -20 μm band infrared radiation were analyzed based on Mie scattering theory and Monte Carlo method. The results show that for the small size dust particles, the extinction effect is mainly the result of scattering in the near aThe extinction and attenuation characteristics of seven modes of sandstorm in China for 0.86 -20 μm band infrared radiation were analyzed based on Mie scattering theory and Monte Carlo method. The results show that for the small size dust particles, the extinction effect is mainly the result of scattering in the near and middle infrared, and for the large size dust particles, the infrared extinction is the result of absorption and scattering. The attenuation rate difference of single scattering and multiple scattering of sandstorm are compared. The attenuation rate of multiple scattering is less than that of single scattering under the same condition, and the difference decreases with the increase of visibility. The multiple scattering attenuation rate calculated based on Monte Carlo method is more comprehensive than the extinction coefficient to reflect the influence of sandstorm on infrared radiation intensity attenuation. The infrared attenuation intensity of six kinds of large particle mode sandstorm is greater than that of small particle mode sandstorm, and the attenuation rate increases with the increase of wavelength. The attenuation rate of the small particle mode duststorm fluctuates obviously with the change of wavelength, with a peak value in the range of 7.9–12.5 μm, and is not sensitive to the wavelength in the range of 13–20 μm..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20201022 (2020)
Experimental study on extinction characteristics of aqueous foam(Invited)
Gongpei Pan, Xuefeng Du, and Jun Zhao
Aqueous foam is widely used as a kind of stealth way in the scene of optoelectronic countermeasure. The existing optoelectronic jamming stealth technology has such problems as short acting time, single band and environmental pollution, which makes it difficult to effectively counter dual-mode and multi-mode precision gAqueous foam is widely used as a kind of stealth way in the scene of optoelectronic countermeasure. The existing optoelectronic jamming stealth technology has such problems as short acting time, single band and environmental pollution, which makes it difficult to effectively counter dual-mode and multi-mode precision guidance weapons. Aiming at the above problems, the aqueous foam formulation was studied. The extinction performance experiments of aqueous foam against visible light, infrared (3-5 μm, 8-14 μm), laser (1.06 μm, 10.6 μm), millimeter wave (3 mm, 8 mm) and centimeter wave (2 cm, 3 cm)were implemented. The shielding and interference effects of aqueous foam aiming at thermal imagery of 8-14 μm band were measured. The extinction mechanism of aqueous foam was discussed. The study shows that the curtain barrier formed by aqueous foam cloud or compositing with artificial fog is expected to acquire a new type of smokescreen weapon with the advantages such as full-wave band and environment friendly..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20201023 (2020)
[in Chinese]
Networking method of multi-view stereo-vision measurement network
Yujing Qiao, Baoming Jia, Jingang Jiang, and Jingyi Wang
Stereo-vision network measurement was the core technology for 3D measurement. In order to ensure the full coverage and reconstruction accuracy of 3D reconstruction, the camera needed to be intensively shot during the measurement process, resulting in slow 3D measurement and large calculation.Therefore, a multi-view steStereo-vision network measurement was the core technology for 3D measurement. In order to ensure the full coverage and reconstruction accuracy of 3D reconstruction, the camera needed to be intensively shot during the measurement process, resulting in slow 3D measurement and large calculation.Therefore, a multi-view stereo-vision measurement network networking method was proposed to solve the above problems. Firstly, the object model was obtained by SFM technology (motion recovery structure), establishing the ellipsoid reference coordinates, estimating the optimal distance between the camera and the object to be tested, and arranging the initial viewpoint position. Secondly, the minimum number of cameras, to achieve full coverage 3D imaging, was filtered based on visual constraints to cluster analysis and loop iteration of the initial viewpoint. Finally, the measurement experiment was carried out, and the ellipsoidal measurement network with the lampshade as the object to be tested was arranged. The comparison of the number of cameras, coverage and measurement accuracy with the spherical measurement network was carried out at different depths of field. The experimental results show that 22 viewpoints are selected through the final iteration of the method, so that the coverage rate reached 100%. The standard deviation of the measurement accuracy was stable to 1.1 mm and the measurement efficiency was significantly improved compared with the spherical network. The original appearance of the object to be tested was restored through the 3D reconstruction of the lampshade rendering, which verified the feasibility of the proposed method..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190492 (2020)
Design of a hybid ultrasound and digital holography imaging system for detection of internal micro-defects
Xing Wang, Lei Gao, Yan Wang, and Haitao Wang
Non-contact detection of internal micro-defects of the micro-electro-mechanical system and minimechanism required a high accuracy and strong penetration test. The current detection methods were difficult to achieve high precision while also having strong penetrating power. In response to the above problems, a compositeNon-contact detection of internal micro-defects of the micro-electro-mechanical system and minimechanism required a high accuracy and strong penetration test. The current detection methods were difficult to achieve high precision while also having strong penetrating power. In response to the above problems, a composite system of ultrasonic detection and digital holography imaging was designed. Ultrasonic detection technology had strong penetrating power, and digital holographic imaging had higher resolution. The composite system designed included a near-field ultrasonic subsystem, an digital holographic subsystem and a synchronous control subsystem. In the near-field ultrasonic subsystem, the generated near-field ultrasonic wavefields passed through the internal defect of the sample and formed the surface ultrasonic wavefield on the surface of the sample. The digital holographic subsystem mainly measured and analyzed the transient morphology of the surface ultrasonic wavefields, and the internal defect information contained in the surface ultrasonic wavefield could be analyzed. The experimental results show that the system can measure the transient 3D topography of the ultrasonic wavefield by analyzing the ultrasonic wavefield, and can effectively detect internal defects of 50 μm..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190518 (2020)
Detection of microcrack in inductor based on orthogonal scanning line laser thermography
Xiaona Wang, Yishu Zhang, Dexin Hou, and Shuliang Ye
In the detection of microcrack on the surface of ferrite inductors, traditional machine vision detection has problems such as low signal-to-noise ratio and low detection accuracy. In order to solve these problems, a microcrack thermography detection system based on line laser orthogonal scanning was built. The surface In the detection of microcrack on the surface of ferrite inductors, traditional machine vision detection has problems such as low signal-to-noise ratio and low detection accuracy. In order to solve these problems, a microcrack thermography detection system based on line laser orthogonal scanning was built. The surface temperature change of the sample was recorded by the thermal imager and imaged. Sub-maximum filtering was used to eliminate non-uniformity and edge contour interference of the thermographic image. And the multi-directional fan-shaped filtering was used to obtain the grayscale image of the sample in different directions. Finally, qualitative detection of microcracks on the surface of the inductor was realized by BP neural network and morphological processing. The results show that all cracks and microcracks are correctly imaged based on 610 samples in two specifications. The automatic identification algorithm has a false detection rate of 5%, a crack miss detection rate of 6%, and a microcrack detection rate of 10%. The system detects 20 to 35 inductors every 5 s and can be used for automated quality inspection in production..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190522 (2020)
Boresight parameters calibration method of VMLS system based on reference planar features constraint
Jiayong Yu, Lang Cheng, Maoyi Tian, Xiushan Lu, Longcheng Ma, Maolun Zhou, Yuefei Cao, and Guoyu Li
The vehicle mobile laser scanning (VMLS) system is a highly integrated multi-sensor measurement system. The accuracy of the VMLS system depends on the accuracy of not only the integrated sensor, but also the calibration of boresight parameters between the laser scanner and the integrated navigation system. Considering The vehicle mobile laser scanning (VMLS) system is a highly integrated multi-sensor measurement system. The accuracy of the VMLS system depends on the accuracy of not only the integrated sensor, but also the calibration of boresight parameters between the laser scanner and the integrated navigation system. Considering the convenience and effectiveness of the calibration method of the boresight parameters and the accuracy evaluation of the VMLS system, a calibrating method of the boresight parameters of the VMLS system based on the reference planar features constraint was proposed. The proposed method was based on the direct georeferencing of lidar measurements including the boresight parameters. The equation used the minimum distance deviation from laser footpoint to reference plane as the constraint. In addition, considering the correlation between rotation and offset amount of the boresight parameters, the stepwise solving method was composed to separate boresight angle and offset parameters. Finally, through the datum acquired from calibration field and check fields, the internal and external accuracy of VMLS system were evaluated. The experimental results show that the proposed method can effectively eliminate the influence of boresight errors. After calibration, the internal accuracy is 0.007 m and the external accuracy is 0.024 m..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190524 (2020)
Defocus projection three-dimensional measurement based on deep learning accurate phase acquisition
Yang Zhao, Jia''an Fu, Haotian Yu, Jing Han, and Dongliang Zheng
The digital fringe projection three-dimensional (3D) measurement technology can generate a sinusoidal fringe pattern for 3D measurement by defocusing a binary fringe pattern. It can achieve extremely high projection speed and has great potential in the field of high-speed 3D measurement. However, the binary fringe pattThe digital fringe projection three-dimensional (3D) measurement technology can generate a sinusoidal fringe pattern for 3D measurement by defocusing a binary fringe pattern. It can achieve extremely high projection speed and has great potential in the field of high-speed 3D measurement. However, the binary fringe pattern inevitably contains higher-order harmonics, resulting in a phase error introduced into the calculated phase, thereby reducing the accuracy of high-speed 3D measurement. A 3D measurement method for defocused projection based on deep learning accurate phase acquisition was proposed. The image feature processing capability based on deep learning algorithm can remove the phase errors introduced by higher-order harmonics. An end-to-end deep convolutional neural network from noise phase to precise phase was constructed by this method and the phase error introduced by higher-order harmonics was reduced. Finally, high-speed and accurate 3D measurement could be achieved by this method. Firstly, the theoretical analysis proved the feasibility of the proposed method. Then, simulation and experiments were performed to further verify the effectiveness and accuracy of the proposed method. Compared with the existing high-speed 3D measurement methods, the proposed method can ensure measurement speed while ensuring measurement accuracy..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20200012 (2020)
[in Chinese]
Study on depolarizers applied for a grating spectrometer
Ting Tan, and Tongzhou Wu
The image quality of the grating spectrometer is often affected by the polarization characteristics of the incident light. In order to solve this problem, a depolarizer is usually added to the spectrometer to reduce the polarization response of the instrument. The birefringence property of the crystalline material can The image quality of the grating spectrometer is often affected by the polarization characteristics of the incident light. In order to solve this problem, a depolarizer is usually added to the spectrometer to reduce the polarization response of the instrument. The birefringence property of the crystalline material can produce a depolarization effect on the optical principle, therefore it is often used to process into various types of depolarizers. Based on the principle of the matrix optics, the Muller matrix and residual polarization theoretical expression of a H-V depolarizer and a double Barbinet depolarizer were deeply discussed. The relationship among residual polarization of a double Barbinet depolarizer and working wavelength, its wedge angle, entrance pupil diameter and incident light polarization angle was given respectively. Based on these theories, a double Barbinet depolarizer applied for a grating spectrometer was developed. It could be obtained by calculation that when the wedge angle and the pupil diameter of the double Barbinet depolarizer was 0.6° and 20.6 mm respectively, the residual polarization of the depolarizer was better than 3% in the wavelength range of 0.4-0.9 μm. What’s more, the double image distance met the application requirements, so it can be widely used in engineering practice..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190544 (2020)
[in Chinese]
Integrative design of structure control for two-axis fast steering mirror with flexible support
Zhiwei Ai, Jianbo Ji, Pengjv Wang, Jing Li, and Haoyang Zhou
To predict and confirm the frequency characteristics and time-domain performance of the fast steering system (FSM) in the structural design stage, a two-axis flexible-supported FSM was studied and tested. A new flexible support structure was proposed, and the main structural parameters of the FSM system were designed bTo predict and confirm the frequency characteristics and time-domain performance of the fast steering system (FSM) in the structural design stage, a two-axis flexible-supported FSM was studied and tested. A new flexible support structure was proposed, and the main structural parameters of the FSM system were designed based on the performance index of FSM which is decided by the beam requirement of laser transmission system. The dynamic mathematical model of the system was studied, and the control mode and parameters of the closed-loop system were determined. The rigid-flexible coupling model of the swing part of the system was established, and the structural non-linear model was obtained. The joint simulation test of the system and the motion system were carried out based on the model above. The simulation results show that the resonance frequency of the system in the direction of motion is 54 Hz, and the errors between the calculated result and the finite element result is both 3.8%, and position closed loop bandwidth is 203 Hz which is right to the index. The output results in time domain show that the overshoot of the system is 3.5% and the adjustment time is 10 ms, the deviations from the theoretical results are 3% and 5 ms..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190479 (2020)
Optical design of infrared dual band/dual field of view seeker
Yankai Mao, Zhenyu Zhao, Guohua Zhang, and Guangyu Shi
At present, most of the strapdown seekers use the combination of infrared single band and single field of view to match and intercept the target, but this method is susceptible to factors such as target/background characteristic, detector performance, field of view in increasingly complex battlefield environment. On thAt present, most of the strapdown seekers use the combination of infrared single band and single field of view to match and intercept the target, but this method is susceptible to factors such as target/background characteristic, detector performance, field of view in increasingly complex battlefield environment. On the basis of retaining the original single medium wave infrared large field of view of a strapdown seeker, a new type of IR dual band/dual field of view seeker was proposed by adding two long wave large and small field of view. By using the image fusion of medium and long wave dual band and the switching of dual field of view under long wave infrared, the difference between target and background feature information was highlighted, which can effectively improve the interception probability of missile to target. The optical system was designed with CODE V software. The whole system adopted the common aperture optical design, which had good imaging quality and meets the system requirements..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190490 (2020)
Design of large-aperture variable-direction mirror for space remote sensing camera
Fengqin Zhang, Lianying Dou, Shoucheng Pang, and Qinglin Li
With the development of remote sensing technology, new camera requires large aperture variable-direction mirrors with higher accuracy. A new type of back support structure with highly stable support design was proposed for 1 000 mm×700 mm large-aperture variable-direction mirror. Compared with the conventional desWith the development of remote sensing technology, new camera requires large aperture variable-direction mirrors with higher accuracy. A new type of back support structure with highly stable support design was proposed for 1 000 mm×700 mm large-aperture variable-direction mirror. Compared with the conventional design, it had the characteristics of small volume envelope, light weight and wide adaptability. The mirror was made of ULE, and the light weight form of honeycomb layer was used. The mirror was mounted by means of a 3-point ball joint flexures system on the back. The stress in reflector assembling and the influence of thermal stress on the orbit was eliminated. It reached the stress-free support of the mirror. The problem of consistency between the ground test and in orbit was solved through the design of gravity unloading structure and the optimization of the unloading force. The simulation analysis shows that the surface RMS is 0.006λ(λ=632.8 nm) at 90° mirror testing direction. The surface RMS is 0.005λ at 75° camera imaging testing direction Ⅰ. The surface RMS is 0.011λ at 45° camera imaging testing direction Ⅱ. The first order modal of the component is 83.2 Hz, which has a high design stiffness and can meet the requirements of the mechanical environment during launch. This large-aperture variable-direction mirror design can meet the needs of new types of remote sensor and can provide a reference for the design of similar mirrors..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20200008 (2020)
[in Chinese]
640×512 digital InGaAs detector assembly
Shengyou Zhong, Nan Chen, Mingguo Fan, Jiqing Zhang, Qin Zhu, and Libin Yao
Digital InGaAs detector significantly orients the development of short wave (SW) infrared detector technology, it not only can increase integrated level of the system, but also can develop the imager’s performance. The key point to realize the digital InGaAs detector is integrating ADC into the readout integrated circuDigital InGaAs detector significantly orients the development of short wave (SW) infrared detector technology, it not only can increase integrated level of the system, but also can develop the imager’s performance. The key point to realize the digital InGaAs detector is integrating ADC into the readout integrated circuit (ROIC) and realize digital ROIC (DROIC). The 640×512 DROIC was designed and fabricated, it interconnected InGaAs detector focal plane array with In and realized digital InGaAs detector assembly. The proposed digital InGaAs detector assembly was tested, and the measurement results show that its readout noise is 230 μV, peak quantum efficiency is 65%, detectivity under 300 K temperature is 1.2×1012 cm Hz1/2 / W, and the power consumption is 94 mW when frame rate is 60 Hz. The measurement results indicate that the digital InGaAs detector assembly has some features as low readout noise, high linearity, wide transmission bandwidth, good resistance to interference and so on..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190495 (2020)
Influences of weather conditions on vehicular infrared assistant driving performance
Hongpei Wang, Guangqi Luan, Chao Tian, Jiaxiao Wang, Peng Yang, and Mingzhao Sun
Based on comprehensive analysis of vehicle infrared assisted driving safety braking process, infrared static detection model and dynamic detection model, the model of visual range for assistant driving safety was established. The relationship between maximum safe speed, road condition, infrared detection performance waBased on comprehensive analysis of vehicle infrared assisted driving safety braking process, infrared static detection model and dynamic detection model, the model of visual range for assistant driving safety was established. The relationship between maximum safe speed, road condition, infrared detection performance was analyzed. It is found that it is mainly related to sliding adhesion coefficient and detection distance. Through the correction calculation of infrared detection distance, the maximum safe speed at night was simulated. The results show that it is mainly affected by the temperature difference between target and background. Emphasis is laid on foggy and rainy weather for example analysis. The results show that foggy weather mainly affects the detection distance, especially when the visibility is less than 1 km, and the maximum safe speed need be controlled at 21-25 km/h when the visibility is 5 km. Rainy weather will affect the sliding adhesion coefficient and detection distance. The maximum safe speed control under infrared recognition is the main method for assistant driving. When rainfall intensity is 50 mm/h, the maximum safe speed need be controlled at 12-14 km/h..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190507 (2020)
Simulation analysis of influence of aerodynamic heating effect of dome window on rosette scan system
Yinhuan Lv
Aiming at the influence of the aerodynamic heating effect of the high-speed vehicle on the optical performance of the vehicle, the heat radiation model of the dome window of the vehicle was established. On this basis, the simulation control program was programmed, and the optical automatic tracing was realized by usingAiming at the influence of the aerodynamic heating effect of the high-speed vehicle on the optical performance of the vehicle, the heat radiation model of the dome window of the vehicle was established. On this basis, the simulation control program was programmed, and the optical automatic tracing was realized by using TracePro software, and the thermal effect of the dome window produced during the scanning of the entire optical system, as well as the effects of individual optical moving parts when scanned separately were dynamically simulated. Through the analysis of the transmission path of stray light caused by thermal effect in the process of rosette scanning, the proposed improvement measures were obtained, which provided a reference for the optical performance analysis and environmental failure research of high-speed vehicle..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190520 (2020)
Infrared light field relay imaging system based on micro field lens array
Tengfei Wang, Yonghe Chen, and Yutian Fu
Light field imaging is a method of imaging by acquiring light field information and refocusing on a specific plane. With the limitation of the light field camera structure, the detector is generally modified to achieve coupling of the microlens array and the detector. It is not applicable to infrared light field cameraLight field imaging is a method of imaging by acquiring light field information and refocusing on a specific plane. With the limitation of the light field camera structure, the detector is generally modified to achieve coupling of the microlens array and the detector. It is not applicable to infrared light field cameras. To this end, a novel structure of a micro field lens array combined with a relay lens was proposed. This new structure utilized a relay lens to image the intermediate image plane at a 1:1 ratio and eliminated the vignetting of the relay lens through the micro field lens array. The modulation transfer function curve of the system was calculated by the slanted edge method. The image quality of direct coupling, relay lens coupling and new structure coupling were compared. According to different refocus planes, the curve value of the new coupling structure at Nyquist frequency was increased by 5%-240% compared with that of the relay lens coupling structure. It was close to the curve value of the direct coupling structure. The new structure can realize coupling and avoid the sharp decrease of system image quality. It plays an important role in the infrared field camera..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190548 (2020)
[in Chinese]
Modeling research on angle measurement accuracy of four-quadrant detector of laser seeker
Xiong Qiu, Shicheng Wang, Zhiguo Liu, and Weibo Xu
The accuracy of the four-quadrant detector on the target directly affects the guidance precision of the laser guided weapon. Therefore, it is very important to study the accuracy of the four-quadrant detector. In this paper, the method of computation and simulation analysis was adopted, based on the uniform distributioThe accuracy of the four-quadrant detector on the target directly affects the guidance precision of the laser guided weapon. Therefore, it is very important to study the accuracy of the four-quadrant detector. In this paper, the method of computation and simulation analysis was adopted, based on the uniform distribution of the pulse peak power density at the entrance of the seeker, and the noise interference current obeyed the Gaussian distribution, and the beam deflection angle error model of the laser seeker was established; however, the beam deflection angle error had random probability due to noise interference, so the mean and standard deviation of the beam deflection angle error were used as the measurement of the four-quadrant detector angle measurement accuracy. The relationship was established between the mean and standard deviation of the beam deflection angle error and the optical parameters of the seeker, the spot radius, the incident angle of the diffuse reflection laser, the noise interference current, and the pulse peak power density at the entrance of the seeker. Taking the standard deviation of the deflection angle of the seeker beam as an example, the simulation analysis was carried out in combination with the application background..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190453 (2020)
Status and development trend of high power slab laser technology
Huihua Wang, Longxin Lin, and Xin Ye
As a typical high-power solid-state laser, high average power zigzag slab lasers achieved great progress in past two decades. Which fields got many innovations, such as face-pumped slab amplifier, multi-segment bonded slab structure, high-brightness pumped Yb: YAG slab amplifier and so on. This paper reviewed the technAs a typical high-power solid-state laser, high average power zigzag slab lasers achieved great progress in past two decades. Which fields got many innovations, such as face-pumped slab amplifier, multi-segment bonded slab structure, high-brightness pumped Yb: YAG slab amplifier and so on. This paper reviewed the technology progress of the slab lasers, including its design principles, transmission power amplification rules and various improvement methods for optimizing performance.On the basis of the general discussion on the laser power calibration capability of the slats, the technical development trend of improving the output power and beam quality was analyzed and discussed. It was expected that there will be considerable development space for high average power slab laser technology in the future..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190456 (2020)
Anti-interference temperature control for VCSEL laser
Tian Han, Yulin Zhang, Cunxiao Miao, Jianfeng Liu, and Shuai Xue
Due to its low power consumption, small size, high modulation frequency and easy integration, VCSELs are widely used in the field of magnetic detection. As a high-precision sensor, the atomic magnetometer reduces the measurement accuracy due to the unstable output of the laser during the measurement of the magnetic fieDue to its low power consumption, small size, high modulation frequency and easy integration, VCSELs are widely used in the field of magnetic detection. As a high-precision sensor, the atomic magnetometer reduces the measurement accuracy due to the unstable output of the laser during the measurement of the magnetic field. A controller that can resist change in ambient temperature was designed to deal with the instability of the output of the laser due to environmental disturbance. Firstly, the high-resolution temperature solution was realized by the ADAU1401A chip with DSP core and DPSD method. Then the temperature control mathematical model was established by means of system identification. Finally, the disturbance observer and internal model control principle were applied to design anti-disturbance and low overshoot robust controller. The experimental results show that the control accuracy of interference is ±0.003 °C at 70 °C, and the control accuracy is ±0.001 5 °C at room temperature, which lays a foundation for stable output of laser and high-precision magnetic field measurement..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190461 (2020)
Miniaturized mid-infrared MgO: PPLN optical parametric oscillator with high beam quality
Xiang Bai, Yang He, Deyang Yu, Kuo Zhang, and Fei Chen
In order to meet the engineering application of mid-infrared laser, a miniaturized mid-infrared MgO: PPLN optical parametric oscillator (MgO: PPLN-OPO) with high beam quality was presented. The pump source was an acousto-optical Q-switched Nd: YVO4 laser. By pumping the MgO: PPLN crystal, the mid-infrared laser with hiIn order to meet the engineering application of mid-infrared laser, a miniaturized mid-infrared MgO: PPLN optical parametric oscillator (MgO: PPLN-OPO) with high beam quality was presented. The pump source was an acousto-optical Q-switched Nd: YVO4 laser. By pumping the MgO: PPLN crystal, the mid-infrared laser with high efficiency and high peak power was obtained. And the mid-infrared beam quality was improved by adding an aperture in the cavity. The whole laser was cooled by thermoelectric cooling and air cooling. Therefore, the size of the laser was miniaturized. Experimental results indicate that the acousto-optical Q-switched Nd: YVO4 laser can realize the pulse laser with the highest power of 9.3 W at 1.064 μm. The corresponding optical to optical conversion efficiency is 27.2% and the peak power is ~27.5 kW. With the Nd: YVO4 laser pump, the MgO: PPLN-OPO can output the pulse laser at 3.765 μm. When adding the aperture in the cavity, the maximum output power of the MgO: PPLN-OPO decreases from 1.20 W to 1.08 W. However, the beam quality improves obviously. The Mx2 and My2factors change from 1.89 and 1.98 to 1.20 and 1.29, respectively. The pulse width and the peak power of mid-infrared laser are 8.4 ns and ~4.3 kW, respectively..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20190512 (2020)
Single-frequency laser based on single-pass QPM frequency doubling of Tm-doped fiber MOPA
Pengquan Zhang, Tiejun Du, and Yijun Shi
In order to obtain a 0.9 μm near-infrared continuous-wave single-frequency laser output, a 50 mm long PPLN crystal was used to perform single-pass frequency doubling of the continuous-wave 1 925.08 nm single-frequency laser output of the Tm-doped fiber MOPA, and the temperature was matched by focusing parameters and quIn order to obtain a 0.9 μm near-infrared continuous-wave single-frequency laser output, a 50 mm long PPLN crystal was used to perform single-pass frequency doubling of the continuous-wave 1 925.08 nm single-frequency laser output of the Tm-doped fiber MOPA, and the temperature was matched by focusing parameters and quasi-phase optimized to achieve 96.95 nm second harmonic output up to 9.07 W at a fundamental optical power of 43.4 W, with a conversion efficiency of 20.9%.The second harmonic was in single longitudinal mode with M2 factors of 1.36 and 1.52 on x and y directions, respectively. The influence of focusing parameter and temperature on the conversion efficiency was experimentally investigated. The relationship between the focusing parameter and phase matching temperature acceptance was also discussed. The experimental results show that Tm-doped fiber laser quasi-phase matching one-way frequency doubling is an effective method to obtain 0.9 μm band continuous wave single frequency laser output..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20200112 (2020)
[in Chinese]
Image recognition method of anti UAV system based on convolutional neural network
Shan Xue, Zhen Zhang, Qiongying Lv, Guohua Cao, and Yiwei Mao
In view of the serious impact and threat to public security of UAV''s undocumented flight and random flight, an anti UAV system was proposed. Recognition of UAV is one of the key points in the realization of anti UAV system. An image recognition method based on convolutional neural network was proposed. The selIn view of the serious impact and threat to public security of UAV''s undocumented flight and random flight, an anti UAV system was proposed. Recognition of UAV is one of the key points in the realization of anti UAV system. An image recognition method based on convolutional neural network was proposed. The self-made optical system was used to collect images of different UAVs and birds, and convolutional neural network and support vector machine for UAV small sample recognition were designed. The convolution neural network was used to identify MNIST data set, UAV image and bird image respectively. At the same time, support vector machine was used to identify UAV and bird image, and the experiment was carried out. The experimental results show that the recognition accuracy of the convolutional neural network is 91.3% in MNIST data set, 95.9% in UAV recognition and 88.4% in support vector machine (SVM). The experimental results show that the proposed method can identify UAVs, birds and different types of UAVs, and the recognition result is better than that of SVM. It can be used for the identification of UAVs in anti UAV system, which provides reference for similar research..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20200154 (2020)
Lightweight feature fusion network design for local feature recognition of non-cooperative target
Yunfei Xu, Duzhou Zhang, Li Wang, and Baocheng Hua
The Non-cooperative Detection Network(NCDN) model is a kind of local feature detection network based on lightweight convolution neural network. In SSD model, the feature fusion strategy was introduced to meet the detection requirements at different distances, and the robustness of the model to the reduction of local feThe Non-cooperative Detection Network(NCDN) model is a kind of local feature detection network based on lightweight convolution neural network. In SSD model, the feature fusion strategy was introduced to meet the detection requirements at different distances, and the robustness of the model to the reduction of local feature resolution caused by image scale transformation was improved; the number of convolution channels in mobilenetv2 was compressed with different compression ratios to obtain lightweight feature extraction network; local feature labeling and training of speed data were set to verify the applicable distance range of NCDN. The experimental results show that the mAP of the model can reach 0.90 within 45 m, and the accuracy loss of the model is only 5% after saving 75% of the calculation amount in channel compression. It meets the requirements of on orbit detection accuracy and calculation amount..
Infrared and Laser Engineering
- Publication Date: Jul. 01, 2020
- Vol. 49, Issue 7, 20200170 (2020)
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