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RSS2021 Vol. 45, No. 1
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2021, 45(1): 1-6.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.001
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Abstract:
In order to research the influence of the beam waist position on the tightly focusing of the Ince-Gaussian vectorial beam, the superposition theory of orthogonally polarized even and odd modes and the Richards-Wolf vector diffraction integral theory were utilized in this study and the tightly focusing feature of the Ince-Gaussian vectorial beam at the different waist position was analyzed. The results show that under the condition of high numerical aperture focusing, the transverse field structure of the focusing field possessing distribution of light intensity and polarization state can still remain stable when the distance zi between the beam waist position of the Ince-Gaussian vectorial field and the lens changes within a certain Rayleigh length zR (zi < 0.5zR). By analyzing the phase structure of the focusing field, the reason of the instability of the transverse field structure is given when the distance zi between the beam waist position and the lens exceeds a certain Rayleigh length zR (zi>0.5zR). At the same time, the longitudinal polarization component of the focusing field, as a degree of freedom of the focusing field, can be used to construct a more abundant vector structured light field. The results can provide great value for the research of complex structure vector optical field in optical micromanipulation and optical information storage.
In order to research the influence of the beam waist position on the tightly focusing of the Ince-Gaussian vectorial beam, the superposition theory of orthogonally polarized even and odd modes and the Richards-Wolf vector diffraction integral theory were utilized in this study and the tightly focusing feature of the Ince-Gaussian vectorial beam at the different waist position was analyzed. The results show that under the condition of high numerical aperture focusing, the transverse field structure of the focusing field possessing distribution of light intensity and polarization state can still remain stable when the distance zi between the beam waist position of the Ince-Gaussian vectorial field and the lens changes within a certain Rayleigh length zR (zi < 0.5zR). By analyzing the phase structure of the focusing field, the reason of the instability of the transverse field structure is given when the distance zi between the beam waist position and the lens exceeds a certain Rayleigh length zR (zi>0.5zR). At the same time, the longitudinal polarization component of the focusing field, as a degree of freedom of the focusing field, can be used to construct a more abundant vector structured light field. The results can provide great value for the research of complex structure vector optical field in optical micromanipulation and optical information storage.
2021, 45(1): 7-12.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.002
Abstract:
In order to strengthen the detection and analysis of vulcanized rubber and its auxiliaries with similar appearance and odor or similar characteristics, the support vector machine modeling method based on improved particle swarm optimization was introduced into the qualitative analysis of terahertz spectrum. The experimental results show that the accuracy of the improved algorithm is larger than 81.25% for different data sets. Compared with support vector machine algorithm optimized by traditional particle swarm optimization, the algorithm also improves the recognition time, and the time spent overall is less than 9.40s. The method can be stably and accurately classified for different data sets, and provides a new research idea for the detection and classification of rubber and its additives.
In order to strengthen the detection and analysis of vulcanized rubber and its auxiliaries with similar appearance and odor or similar characteristics, the support vector machine modeling method based on improved particle swarm optimization was introduced into the qualitative analysis of terahertz spectrum. The experimental results show that the accuracy of the improved algorithm is larger than 81.25% for different data sets. Compared with support vector machine algorithm optimized by traditional particle swarm optimization, the algorithm also improves the recognition time, and the time spent overall is less than 9.40s. The method can be stably and accurately classified for different data sets, and provides a new research idea for the detection and classification of rubber and its additives.
2021, 45(1): 13-18.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.003
Abstract:
In order to improve the efficiency of magnetic pulse compression circuit and reduce its volume, by using PSPICE circuit simulation software and using the method of control variables, the factors that affect the circuit were analyzed and simulated. The simulation analysis was carried out when the nanocrystalline material was used as the core, with the total compression ratio of 100 and the volume of the two-stage magnetic pulse compression circuit at the smallest status. The results show that the pulse rise time is compressed from 6.7μs to 67ns, which meets the requirements of pulse gas laser for fast discharge time; when the load resistance is 250Ω, the first reset current is 1.09A~9.80A, and the second reset current is 3.27A~14.50A, the maximum efficiency of the system is 81.9%; the value of the resistance and the reset current too large or too small will affect the efficiency. This study provides a reference for the further improvement of the efficiency of the magnetic pulse compression circuit and the miniaturization of the volume.
In order to improve the efficiency of magnetic pulse compression circuit and reduce its volume, by using PSPICE circuit simulation software and using the method of control variables, the factors that affect the circuit were analyzed and simulated. The simulation analysis was carried out when the nanocrystalline material was used as the core, with the total compression ratio of 100 and the volume of the two-stage magnetic pulse compression circuit at the smallest status. The results show that the pulse rise time is compressed from 6.7μs to 67ns, which meets the requirements of pulse gas laser for fast discharge time; when the load resistance is 250Ω, the first reset current is 1.09A~9.80A, and the second reset current is 3.27A~14.50A, the maximum efficiency of the system is 81.9%; the value of the resistance and the reset current too large or too small will affect the efficiency. This study provides a reference for the further improvement of the efficiency of the magnetic pulse compression circuit and the miniaturization of the volume.
2021, 45(1): 19-24.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.004
Abstract:
In order to optimize the camera stations in dynamic photogrammetry for large wind turbine blades, an optimization method of photogrammetric network based on improved genetic algorithm for mutation operation was used. A measurement error model was established based on error propagation in the 3-D reconstruction process by front intersecting ray bundles. Taking the standard deviations of the spatial coordinate measurement error as the goal of network optimization, while considering the constraint conditions caused by the wind turbine blade geometry and the actual environment, a simulation experiment was performed to obtain the optimal camera stations. The results show that, in the simulation experiment, the wind turbine with blade length of 40m was taken as the measuring object, the standard deviation of the spatial coordinate measurement errors of the optimal stations is 2.7mm. Real data experiments are conducted on a wind turbine model with 3.5m blade length. The relative measurement error of the optimal station is 0.009%, and the maximum error is 0.617mm. This study provides reference for the network optimization of photogrammetry of wind turbine blades.
In order to optimize the camera stations in dynamic photogrammetry for large wind turbine blades, an optimization method of photogrammetric network based on improved genetic algorithm for mutation operation was used. A measurement error model was established based on error propagation in the 3-D reconstruction process by front intersecting ray bundles. Taking the standard deviations of the spatial coordinate measurement error as the goal of network optimization, while considering the constraint conditions caused by the wind turbine blade geometry and the actual environment, a simulation experiment was performed to obtain the optimal camera stations. The results show that, in the simulation experiment, the wind turbine with blade length of 40m was taken as the measuring object, the standard deviation of the spatial coordinate measurement errors of the optimal stations is 2.7mm. Real data experiments are conducted on a wind turbine model with 3.5m blade length. The relative measurement error of the optimal station is 0.009%, and the maximum error is 0.617mm. This study provides reference for the network optimization of photogrammetry of wind turbine blades.
2021, 45(1): 25-30.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.005
Abstract:
In the fiber optical sensor demodulation based on asymmetric 3×3 coupler, the fiber-optic median phase shift 3×3 adder due to the limitation of the manufacturing process and the susceptibility to external environmental interference, and then the three-way signal output has an uneven splitting ratio and an asymmetric phenomenon that the phase difference cannot meet 120°, which causes a problem that could not be accurately corrected. In order to solve these problems, a new 3×3 replacer was used, and theoretical analysis and experimental verification were performed. The mean two algorithms were used to pre-process any two signals output, and compressed the original three signals. The power and phase difference between the output signals of the two channels make the new three-channel signals after correction to be approximately symmetrical output, and then perform a symmetric algorithm operation. Simulation and experimental results show that the new scheme can effectively correct the asymmetry of the three output signals of the positive 3×3 converter, and classify it. Noise level of the new scheme is about 10-4mW and signal-to-noise ratio is about 50dB. Compared with the traditional alternative scheme, the new structure can obtain higher accuracy and signal-to-noise ratio of the signal under test. In addition, according to the simulation and experimental results, the symmetry conditions of the output of the replacer and the anti-noise capability of the new superposition scheme are analyzed. The result has a good guiding role in the field of optical fiber polarizers and accelerates the practical process of optical fiber sensing technology.
In the fiber optical sensor demodulation based on asymmetric 3×3 coupler, the fiber-optic median phase shift 3×3 adder due to the limitation of the manufacturing process and the susceptibility to external environmental interference, and then the three-way signal output has an uneven splitting ratio and an asymmetric phenomenon that the phase difference cannot meet 120°, which causes a problem that could not be accurately corrected. In order to solve these problems, a new 3×3 replacer was used, and theoretical analysis and experimental verification were performed. The mean two algorithms were used to pre-process any two signals output, and compressed the original three signals. The power and phase difference between the output signals of the two channels make the new three-channel signals after correction to be approximately symmetrical output, and then perform a symmetric algorithm operation. Simulation and experimental results show that the new scheme can effectively correct the asymmetry of the three output signals of the positive 3×3 converter, and classify it. Noise level of the new scheme is about 10-4mW and signal-to-noise ratio is about 50dB. Compared with the traditional alternative scheme, the new structure can obtain higher accuracy and signal-to-noise ratio of the signal under test. In addition, according to the simulation and experimental results, the symmetry conditions of the output of the replacer and the anti-noise capability of the new superposition scheme are analyzed. The result has a good guiding role in the field of optical fiber polarizers and accelerates the practical process of optical fiber sensing technology.
2021, 45(1): 31-36.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.006
Abstract:
In order to process different microstructures on the Ti6Al4V surface and change its wettability to make the surface superhydrophobic, the nanosecond fiber pulsed laser was used to micro-fabricate the Ti6Al4V surface. The effects of the pulse energy density and the scanning interval on the lattice surface morphology and wettability of 3-D microarrays, linear arrays, and surface microstructures were investigated. The results show that the pulse energy and scanning interval affected the surface morphology parameters Sa, Sd, among which, the Sa and Sd of the rid structure were affected the most, followed by the linear array structure, while the lattice structure affected the smallest. After Ti6Al4V was processed by laser, spontaneous transition from superhydrophilic to hydrophobic or even superhydrophobic will occur on the surface. Microstructures processed with different pulse energies and scanning intervals had different degrees of surface wettability improvement, among which the grid structure had the best improvement on the surface wettability, followed by the linear array, and the worst was the lattice; The maximum and minimum contact angles of the grid, linear array, and lattice structure are 165 °, 160.5 °, 142.4 °; 132.9 °, 97 °, 94.6 °, and the surface parameters Sa and Sd with the maximum contact angle are 0.97μm, 1.38; 1.62μm, 1.04; 4.14μm, 2.39, respectively. This research has certain reference significance for improving the surface wettability of Ti6Al4V.
In order to process different microstructures on the Ti6Al4V surface and change its wettability to make the surface superhydrophobic, the nanosecond fiber pulsed laser was used to micro-fabricate the Ti6Al4V surface. The effects of the pulse energy density and the scanning interval on the lattice surface morphology and wettability of 3-D microarrays, linear arrays, and surface microstructures were investigated. The results show that the pulse energy and scanning interval affected the surface morphology parameters Sa, Sd, among which, the Sa and Sd of the rid structure were affected the most, followed by the linear array structure, while the lattice structure affected the smallest. After Ti6Al4V was processed by laser, spontaneous transition from superhydrophilic to hydrophobic or even superhydrophobic will occur on the surface. Microstructures processed with different pulse energies and scanning intervals had different degrees of surface wettability improvement, among which the grid structure had the best improvement on the surface wettability, followed by the linear array, and the worst was the lattice; The maximum and minimum contact angles of the grid, linear array, and lattice structure are 165 °, 160.5 °, 142.4 °; 132.9 °, 97 °, 94.6 °, and the surface parameters Sa and Sd with the maximum contact angle are 0.97μm, 1.38; 1.62μm, 1.04; 4.14μm, 2.39, respectively. This research has certain reference significance for improving the surface wettability of Ti6Al4V.
2021, 45(1): 37-43.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.007
Abstract:
In order to study the effect of laser speckle on target detection, the theoretical analysis of the statistical characteristics of the scattering field when the plane wave laser irradiates the rough sphere and cone target was carried out by using the physical optics approximation method, and the second order statistical moment of the scattering field quantity of rough targets was derived. The variation of incoherent scattering component ratio of rough sphere and cone with roughness, scattering angle, radius, and target material is calculated numerically. The results show that the change of scattering angle has an effect on the incoherent component ratio of rough sphere scattering. The larger the roughness, the larger the proportion of incoherent component of target to the total scattering component. As the radius of the rough sphere becomes smaller, the surface of the sphere becomes rougher. The peak position of incoherent component ratio of cone target scattering varies with roughness, but its peaks are all located in the direction of specular reflection. The incoherent component ratio of metallic materials is smaller than that of non-metallic polished aluminum materials, and the radius change is proportional to the incoherent component ratio. The research results provide some reference value for the study of laser scattering characteristics of more complex targets and laser speckle detection and identification.
In order to study the effect of laser speckle on target detection, the theoretical analysis of the statistical characteristics of the scattering field when the plane wave laser irradiates the rough sphere and cone target was carried out by using the physical optics approximation method, and the second order statistical moment of the scattering field quantity of rough targets was derived. The variation of incoherent scattering component ratio of rough sphere and cone with roughness, scattering angle, radius, and target material is calculated numerically. The results show that the change of scattering angle has an effect on the incoherent component ratio of rough sphere scattering. The larger the roughness, the larger the proportion of incoherent component of target to the total scattering component. As the radius of the rough sphere becomes smaller, the surface of the sphere becomes rougher. The peak position of incoherent component ratio of cone target scattering varies with roughness, but its peaks are all located in the direction of specular reflection. The incoherent component ratio of metallic materials is smaller than that of non-metallic polished aluminum materials, and the radius change is proportional to the incoherent component ratio. The research results provide some reference value for the study of laser scattering characteristics of more complex targets and laser speckle detection and identification.
2021, 45(1): 44-47.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.008
Abstract:
In order to study the potential applications of quantum correlation measurement and Hong-Ou-Mandel(HOM) interference to laser detection and ranging (LADAR) systems, the method for preparing the correlated two-photon source based on dispersion-shifted fiber (DSF) and the HOM interference principle of identical photons was adopted. A correlated two-photon generation platform and a HOM interferometer for weak coherent light interference experiment were assembled for theoretical analysis and experimental verification. The results show that, the correlated two-photon source has the maximum two-photon generation rate and the ratio of coincidence to accidental coincidence count of about 8kHz and 15, respectively. The visibility of HOM interference fringe is 0.41±0.01, HOM interference can improve the time measuring precision of LADAR to 0.95ps±0.03ps, corresponding to a spatial resolution of 284.06μm±9.94μm. The results lay a foundation for further research to improve LADAR performance by using quantum optics technologies.
In order to study the potential applications of quantum correlation measurement and Hong-Ou-Mandel(HOM) interference to laser detection and ranging (LADAR) systems, the method for preparing the correlated two-photon source based on dispersion-shifted fiber (DSF) and the HOM interference principle of identical photons was adopted. A correlated two-photon generation platform and a HOM interferometer for weak coherent light interference experiment were assembled for theoretical analysis and experimental verification. The results show that, the correlated two-photon source has the maximum two-photon generation rate and the ratio of coincidence to accidental coincidence count of about 8kHz and 15, respectively. The visibility of HOM interference fringe is 0.41±0.01, HOM interference can improve the time measuring precision of LADAR to 0.95ps±0.03ps, corresponding to a spatial resolution of 284.06μm±9.94μm. The results lay a foundation for further research to improve LADAR performance by using quantum optics technologies.
2021, 45(1): 48-52.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.009
Abstract:
In order to implement non-contact detection for liquid level less than 100mm in height, the method for changing planar capacitive edge electric field parameters by liquid level was adopted. The working principle of planar capacitive sensor was analyzed, and the effect of planar capacitive sensor structure parameters on sensitivity and penetration depth was studied. The method of structural optimization design on sensors was proposed. The non-contact detection system for lower liquid level was designed based on planar capacitive sensors. The measured data of pure water, detergent solution and ink within 100mm was obtained by experimental verification. The experimental results show that the system with linear output is stable. The repeatability error is about ±0.28%, and the measurement error is within 7.8% before data correction. The results are helpful for non-contact detection for lower liquid level.
In order to implement non-contact detection for liquid level less than 100mm in height, the method for changing planar capacitive edge electric field parameters by liquid level was adopted. The working principle of planar capacitive sensor was analyzed, and the effect of planar capacitive sensor structure parameters on sensitivity and penetration depth was studied. The method of structural optimization design on sensors was proposed. The non-contact detection system for lower liquid level was designed based on planar capacitive sensors. The measured data of pure water, detergent solution and ink within 100mm was obtained by experimental verification. The experimental results show that the system with linear output is stable. The repeatability error is about ±0.28%, and the measurement error is within 7.8% before data correction. The results are helpful for non-contact detection for lower liquid level.
2021, 45(1): 53-60.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.010
Abstract:
Differential absorption lidar has the characteristics of long detection distance, high sensitivity, and fast response. It can be used for remote sensing of large-scale atmospheric toxic and harmful gases, and has become the focus of the development of atmospheric toxic and harmful gas laser telemetry technology in recent years. Firstly, the basic principle of differential absorption lidar atmospheric telemetry is described. Secondly, the development status of the technology is analyzed from two aspects of laser application and system platform development. Finally, the development direction of wide spectrum, multi-wavelength, new detection system lidar, multi-platform application and composite system will become the future toxic and harmful gas telemetry.
Differential absorption lidar has the characteristics of long detection distance, high sensitivity, and fast response. It can be used for remote sensing of large-scale atmospheric toxic and harmful gases, and has become the focus of the development of atmospheric toxic and harmful gas laser telemetry technology in recent years. Firstly, the basic principle of differential absorption lidar atmospheric telemetry is described. Secondly, the development status of the technology is analyzed from two aspects of laser application and system platform development. Finally, the development direction of wide spectrum, multi-wavelength, new detection system lidar, multi-platform application and composite system will become the future toxic and harmful gas telemetry.
2021, 45(1): 61-66.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.011
Abstract:
In order to establish a scientific method for inspecting residual cigarette liners on site, the latest differential spectroscopy technology was used to inspect 44 different brands and different series of samples, and the samples were classified according to the different main fillers in the samples. Combined with chemometrics, the data reduced by principal component analysis was used for cluster analysis, and the significant P value and Pearson correlation coefficient were used to evaluate the quality of the clustering results. The optimal clustering results were used to establish discrimination formula. The results show that the samples can be divided into 4 categories after analyzing and comparing the spectra. The established discriminant realized 100% accurate classification of 44 samples, and provided a basis for the discrimination of unknown samples. In summary, the method combined with spectral analysis and chemometrics can quickly, non-destructively and accurately make objective inspections of samples. It has certain universality and provides a theoretical basis for the actual handling of cases by police.
In order to establish a scientific method for inspecting residual cigarette liners on site, the latest differential spectroscopy technology was used to inspect 44 different brands and different series of samples, and the samples were classified according to the different main fillers in the samples. Combined with chemometrics, the data reduced by principal component analysis was used for cluster analysis, and the significant P value and Pearson correlation coefficient were used to evaluate the quality of the clustering results. The optimal clustering results were used to establish discrimination formula. The results show that the samples can be divided into 4 categories after analyzing and comparing the spectra. The established discriminant realized 100% accurate classification of 44 samples, and provided a basis for the discrimination of unknown samples. In summary, the method combined with spectral analysis and chemometrics can quickly, non-destructively and accurately make objective inspections of samples. It has certain universality and provides a theoretical basis for the actual handling of cases by police.
2021, 45(1): 67-72.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.012
Abstract:
The traditional SO2 detector in China has the problem of low fluorescence intensity in the fluorescence detection area of the gas chamber, which leads to the low monitoring accuracy of the instrument. In order to solve this problem, a new excited optical path structure was designed. In the light path structure, the point light source was collimated by a plane convex lens, and a narrow slit was used to eliminate the far-axis light in the vertical direction. The point light source was converged to the center of the gas chamber fluorescence collection area by a double convex lens, and the interference of stray light was reduced by the diaphragm. The ray tracing algorithm was used as a tool of strict vector analysis to simulate the designed optical path. The results show that the optimized optical path can reduce the energy loss of excitation light to 10%, and the dispersion spot is also greatly reduced. The experimental results show that the indication error of the optical path is changed from 0.34% full scale to 0.18% full scale. The precision of 100μg/L changed from 1.13μg/L to 0.53μg/L. The precision at 400μg/L changed from 2.26μg/L to 1.1μg/L. The two indexes have been improved, which can effectively solve the shortcomings of the traditional optical path.
The traditional SO2 detector in China has the problem of low fluorescence intensity in the fluorescence detection area of the gas chamber, which leads to the low monitoring accuracy of the instrument. In order to solve this problem, a new excited optical path structure was designed. In the light path structure, the point light source was collimated by a plane convex lens, and a narrow slit was used to eliminate the far-axis light in the vertical direction. The point light source was converged to the center of the gas chamber fluorescence collection area by a double convex lens, and the interference of stray light was reduced by the diaphragm. The ray tracing algorithm was used as a tool of strict vector analysis to simulate the designed optical path. The results show that the optimized optical path can reduce the energy loss of excitation light to 10%, and the dispersion spot is also greatly reduced. The experimental results show that the indication error of the optical path is changed from 0.34% full scale to 0.18% full scale. The precision of 100μg/L changed from 1.13μg/L to 0.53μg/L. The precision at 400μg/L changed from 2.26μg/L to 1.1μg/L. The two indexes have been improved, which can effectively solve the shortcomings of the traditional optical path.
2021, 45(1): 73-79.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.013
Abstract:
In order to improve the effective utilization of features in remote sensing image scene classification and achieve the purpose of improving the accuracy of remote sensing image classification, a remote sensing image classification method based on dual-channel depth-dense feature fusion was used for theoretical analysis and experimental verification. First, the image convolution layer features and fully connected layer features was separated extracted by constructing a composite dense convolutional network model. In order to exploit the deep information of the image, the deep convolutional layer features extracted by the model were recombined and encoded by the bag of visual words to capture the deep local features of the image. Finally the linear and weighted methods were used to fuse local and global features and then classify them. The results show that using the datasets UC Merced Land-Use and NWPU-RESISC45 for experiments, the classification accuracy obtained is 93.81% and 92.62%, respectively. This method makes full use of the complementarity of local features and global features to achieve the full expression of deep image information.
In order to improve the effective utilization of features in remote sensing image scene classification and achieve the purpose of improving the accuracy of remote sensing image classification, a remote sensing image classification method based on dual-channel depth-dense feature fusion was used for theoretical analysis and experimental verification. First, the image convolution layer features and fully connected layer features was separated extracted by constructing a composite dense convolutional network model. In order to exploit the deep information of the image, the deep convolutional layer features extracted by the model were recombined and encoded by the bag of visual words to capture the deep local features of the image. Finally the linear and weighted methods were used to fuse local and global features and then classify them. The results show that using the datasets UC Merced Land-Use and NWPU-RESISC45 for experiments, the classification accuracy obtained is 93.81% and 92.62%, respectively. This method makes full use of the complementarity of local features and global features to achieve the full expression of deep image information.
2021, 45(1): 80-85.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.014
Abstract:
In order to study the problem of the guidance accuracy reduction caused by the inconsistency of the four acquisition channels in the information processing circuit of the semi-active laser guidance seeker, the reason of the difference of the response between the sampling channels was analyzed and studied. The gain control circuit in the information processing circuit was studied. The key points of the design were analyzed, and the design principle of a gain control circuit was given. An inter-channel response inconsistency correction method based on the gain control circuit was used to correct the inconsistency of discrete gain points used in the actual flight of a missile (or a bomb). The effectiveness of the correction method was verified by comparing the linear curve before and after correction with the simulation data of hardware-in-the-loop. The experimental results show that the linear circular error probable (CEP) of the seeker is more accurate and the CEP of the semi-physical simulation can be reduced by about 50%. This study provides an effective method for improving the precision of semi-active laser guidance.
In order to study the problem of the guidance accuracy reduction caused by the inconsistency of the four acquisition channels in the information processing circuit of the semi-active laser guidance seeker, the reason of the difference of the response between the sampling channels was analyzed and studied. The gain control circuit in the information processing circuit was studied. The key points of the design were analyzed, and the design principle of a gain control circuit was given. An inter-channel response inconsistency correction method based on the gain control circuit was used to correct the inconsistency of discrete gain points used in the actual flight of a missile (or a bomb). The effectiveness of the correction method was verified by comparing the linear curve before and after correction with the simulation data of hardware-in-the-loop. The experimental results show that the linear circular error probable (CEP) of the seeker is more accurate and the CEP of the semi-physical simulation can be reduced by about 50%. This study provides an effective method for improving the precision of semi-active laser guidance.
2021, 45(1): 86-92.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.015
Abstract:
In order to solve the problem that the different intensity of the same position of the 3-D positron emission tomography(PET) and the magnetic resonance imaging(MRI) image of Alzheimer's disease and retain the MRI atrophy of the cerebral cortex, cerebral sulcus, hippocampus, etc. Two images were firstly pre-processed in SPM to obtain two images. Then, using ShearLab 3D transform to process the advantages of high-dimensional data to decompose to obtain low and high-pass subbands. The high frequency subband was divided into intermediate and high frequency subband with the variance as threshold. The fusion principle of low-pass subbands was based on the method of three-dimensional extended weighted local energy and weighted sum of modified Laplacian based on 26 neighborhoods. The sharpening operator was introduced as a weight parameter to make the edge of the fused image clear. Intermediate subband enhances the edge information with absolute value activity. The high-pass subbands were combined with three three-dimensional low-level visual features to enhance the detailed features of the image. Finally, PET/MRI fusion images were obtained using ShearLab 3D inverse transform. The results show that the fusion result of ShearLab 3D transform is better than the spatial algorithm and wavelet transform as a whole. In the ShearLab 3D method, different fusion rules are compared and analyzed. The average gradient, spatial frequency, edge strength, and comprehensive entropy of the fusion result of this algorithm were improved by 11.09%, 22.58%, 152.68%, and 0.58%, respectively. It solves the problems of blurred edges and unclear details in fusion image. This study provides a reference for PET/MRI image fusion.
In order to solve the problem that the different intensity of the same position of the 3-D positron emission tomography(PET) and the magnetic resonance imaging(MRI) image of Alzheimer's disease and retain the MRI atrophy of the cerebral cortex, cerebral sulcus, hippocampus, etc. Two images were firstly pre-processed in SPM to obtain two images. Then, using ShearLab 3D transform to process the advantages of high-dimensional data to decompose to obtain low and high-pass subbands. The high frequency subband was divided into intermediate and high frequency subband with the variance as threshold. The fusion principle of low-pass subbands was based on the method of three-dimensional extended weighted local energy and weighted sum of modified Laplacian based on 26 neighborhoods. The sharpening operator was introduced as a weight parameter to make the edge of the fused image clear. Intermediate subband enhances the edge information with absolute value activity. The high-pass subbands were combined with three three-dimensional low-level visual features to enhance the detailed features of the image. Finally, PET/MRI fusion images were obtained using ShearLab 3D inverse transform. The results show that the fusion result of ShearLab 3D transform is better than the spatial algorithm and wavelet transform as a whole. In the ShearLab 3D method, different fusion rules are compared and analyzed. The average gradient, spatial frequency, edge strength, and comprehensive entropy of the fusion result of this algorithm were improved by 11.09%, 22.58%, 152.68%, and 0.58%, respectively. It solves the problems of blurred edges and unclear details in fusion image. This study provides a reference for PET/MRI image fusion.
2021, 45(1): 99-104.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.017
Abstract:
In order to solve the problems that the measurement efficiency cannot be guaranteed, the precision is not up to the standard, and the task is often omitted during the measurement process, the establishment of the measurement field was planned and studied. Taking lidar measurement system as the carrier, the measurement model of the system was analyzed by monte carlo simulation method, and the establishment process of the whole period of the measurement field, including station configuration, station layout optimization, data acquisition method selection and measurement data preprocessing, was theoretically analyzed and experimentally verified. The results show that the precision of the planned lidar measurement field can reach less than 0.05mm, and the single point measurement precision can reach less than 0.1mm, which conforms to the accuracy requirements of the large-size space measurement field and realizes the planning evaluation of the measurement field. This research has certain significance in the field of large-scale measurement.
In order to solve the problems that the measurement efficiency cannot be guaranteed, the precision is not up to the standard, and the task is often omitted during the measurement process, the establishment of the measurement field was planned and studied. Taking lidar measurement system as the carrier, the measurement model of the system was analyzed by monte carlo simulation method, and the establishment process of the whole period of the measurement field, including station configuration, station layout optimization, data acquisition method selection and measurement data preprocessing, was theoretically analyzed and experimentally verified. The results show that the precision of the planned lidar measurement field can reach less than 0.05mm, and the single point measurement precision can reach less than 0.1mm, which conforms to the accuracy requirements of the large-size space measurement field and realizes the planning evaluation of the measurement field. This research has certain significance in the field of large-scale measurement.
2021, 45(1): 105-108.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.018
Abstract:
Photodetectors based on InGaAs nanowires have been widely studied due to their excellent properties. The detection mechanism, material structure, device performance and current research status of InGaAs nanowire photodetectors were reviewed. The key technologies, such as the structure design of InGaAs nanowire avalanche focal plane detector, the precise growth of nanowire materials, the interface and defect control of nanowire materials, and the preparation process of nanowire avalanche focal plane devices were discussed. On this basis, the prospect of developing high photon detection efficiency, low noise and high gain InGaAs nanowire avalanche focal plane detector was prospected.
Photodetectors based on InGaAs nanowires have been widely studied due to their excellent properties. The detection mechanism, material structure, device performance and current research status of InGaAs nanowire photodetectors were reviewed. The key technologies, such as the structure design of InGaAs nanowire avalanche focal plane detector, the precise growth of nanowire materials, the interface and defect control of nanowire materials, and the preparation process of nanowire avalanche focal plane devices were discussed. On this basis, the prospect of developing high photon detection efficiency, low noise and high gain InGaAs nanowire avalanche focal plane detector was prospected.
2021, 45(1): 109-114.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.019
Abstract:
The extreme ultraviolet (EUV) light conversion efficiency of the laser-produced tin plasma is closely related to the plasma characteristics. To diagnose the parameters of tin plasma, a Langmuir probe for laser-produced plasma diagnosis was designed. And the time evolution of electron temperature and electron density of tin plasma produced by different laser energies were studied. The results show that the peak electron density of the plasma is about 4.5×1011cm-3 with laser energy of 58.1mJ, and the maximum electron temperature is 16.5eV, which decreased with the reduction of laser energy. Moreover, the evolution trends of electron temperature measured by Langmuir probe and emission spectrometry are consistent. This study provides a new simple and rapid diagnostic method for laser-produced plasma EUV light source, which is beneficial to optimize the parameters of EUV light.
The extreme ultraviolet (EUV) light conversion efficiency of the laser-produced tin plasma is closely related to the plasma characteristics. To diagnose the parameters of tin plasma, a Langmuir probe for laser-produced plasma diagnosis was designed. And the time evolution of electron temperature and electron density of tin plasma produced by different laser energies were studied. The results show that the peak electron density of the plasma is about 4.5×1011cm-3 with laser energy of 58.1mJ, and the maximum electron temperature is 16.5eV, which decreased with the reduction of laser energy. Moreover, the evolution trends of electron temperature measured by Langmuir probe and emission spectrometry are consistent. This study provides a new simple and rapid diagnostic method for laser-produced plasma EUV light source, which is beneficial to optimize the parameters of EUV light.
2021, 45(1): 115-120.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.020
Abstract:
In order to suppress speckle noise during holographic recording, a coherence method by reducing the coherent light source was used, and the theoretical analysis and experimental verification were performed. A rotating binary wave plate was used for depolarization, and 70 holograms were recorded in 10s for average noise reduction. At the same time, ground glass was used for spatial decoherence of the coherent light, which reduces the coherence of the light source and thus the speckle noise. The reconstructed image with the temporal depolarization operation alone was compared with the reconstructed image with the spatial depolarization operation alone, and the reconstructed image combining the two. The feasibility of the proposed method was verified by experiments, and several methods were confirmed by analyzing the frequency spectrum comparison. The signal-to-noise ratio was used to directly confirm the effectiveness of several methods. The experimental results show that the combination of time and space depolarization has obvious advantages in suppressing speckle noise. The signal-to-noise ratio of the reconstructed image with spatial depolarization is 0.4459, the reconstructed image with time depolarization is 1.5155, and the combined image with time depolarization is 1.7162. The method of time decrement and space decrement stack is used to suppress the coherent noise effectively. This experiment provides an effective method for the study of speckle noise caused by the over-high coherence of light source in the process of digital holographic imaging.
In order to suppress speckle noise during holographic recording, a coherence method by reducing the coherent light source was used, and the theoretical analysis and experimental verification were performed. A rotating binary wave plate was used for depolarization, and 70 holograms were recorded in 10s for average noise reduction. At the same time, ground glass was used for spatial decoherence of the coherent light, which reduces the coherence of the light source and thus the speckle noise. The reconstructed image with the temporal depolarization operation alone was compared with the reconstructed image with the spatial depolarization operation alone, and the reconstructed image combining the two. The feasibility of the proposed method was verified by experiments, and several methods were confirmed by analyzing the frequency spectrum comparison. The signal-to-noise ratio was used to directly confirm the effectiveness of several methods. The experimental results show that the combination of time and space depolarization has obvious advantages in suppressing speckle noise. The signal-to-noise ratio of the reconstructed image with spatial depolarization is 0.4459, the reconstructed image with time depolarization is 1.5155, and the combined image with time depolarization is 1.7162. The method of time decrement and space decrement stack is used to suppress the coherent noise effectively. This experiment provides an effective method for the study of speckle noise caused by the over-high coherence of light source in the process of digital holographic imaging.
2021, 45(1): 121-125.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.021
Abstract:
In order to accurately measure the absolute spectral response efficiency of the photoelectric imaging system, the optical energy transfer formula of the optical system and the physical model of the image sensor were analyzed, and the calculation formula of the absolute spectral response efficiency of the photoelectric imaging system was obtained. Based on the theoretical formula, an absolute spectral response efficiency measurement device for the photoelectric imaging system based on integrating spheres, multispectral light source of light-emitting diode, standard detector, and a transmission-type parallel light tube was designed. Experimental measurement and analysis of visible light digital cameras with known spectral response efficiency was carried out. The results show that, the absolute spectral response efficiency of the visible light digital camera measured by the measuring device in the wavelength range of 380nm~1100nm is in good agreement with the standard value, and the maximum relative error is 1.7%. When the probability is 95%, it is less than 0.2%, which meets the general measurement requirements. The device can accurately measure the absolute spectral effect efficiency of the photoelectric imaging system.
In order to accurately measure the absolute spectral response efficiency of the photoelectric imaging system, the optical energy transfer formula of the optical system and the physical model of the image sensor were analyzed, and the calculation formula of the absolute spectral response efficiency of the photoelectric imaging system was obtained. Based on the theoretical formula, an absolute spectral response efficiency measurement device for the photoelectric imaging system based on integrating spheres, multispectral light source of light-emitting diode, standard detector, and a transmission-type parallel light tube was designed. Experimental measurement and analysis of visible light digital cameras with known spectral response efficiency was carried out. The results show that, the absolute spectral response efficiency of the visible light digital camera measured by the measuring device in the wavelength range of 380nm~1100nm is in good agreement with the standard value, and the maximum relative error is 1.7%. When the probability is 95%, it is less than 0.2%, which meets the general measurement requirements. The device can accurately measure the absolute spectral effect efficiency of the photoelectric imaging system.
2021, 45(1): 126-130.
doi: 10.7510/jgjs.issn.1001-3806.2021.01.022
Abstract:
Laser guided weapons have the characteristics of high hit precision, long-range precision strike, high combat efficiency and strong anti-jamming capability, and gradually become the leading role of modern war weapons. As an important component of laser guided weapon system, laser ranging target indicator has long been paid attention to by foreign countries' military, and many types of laser ranging target indicators have been developed and equipped. In order to facilitate domestic research on similar products, the development history of foreign ground laser ranging target indicators was summarized, the basic working principles of laser guided weapons and laser ranging target indicators were introduced, and the development trend of ground laser ranging target indicators was analyzed based on the development status quo, which provides reference for domestic research on similar products and photoelectric countermeasures.
Laser guided weapons have the characteristics of high hit precision, long-range precision strike, high combat efficiency and strong anti-jamming capability, and gradually become the leading role of modern war weapons. As an important component of laser guided weapon system, laser ranging target indicator has long been paid attention to by foreign countries' military, and many types of laser ranging target indicators have been developed and equipped. In order to facilitate domestic research on similar products, the development history of foreign ground laser ranging target indicators was summarized, the basic working principles of laser guided weapons and laser ranging target indicators were introduced, and the development trend of ground laser ranging target indicators was analyzed based on the development status quo, which provides reference for domestic research on similar products and photoelectric countermeasures.
