Proceedings Volume 11023

Fifth Symposium on Novel Optoelectronic Detection Technology and Application

Qifeng Yu, Wei Huang, You He
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Proceedings Volume 11023

Fifth Symposium on Novel Optoelectronic Detection Technology and Application

Qifeng Yu, Wei Huang, You He
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Volume Details

Date Published: 12 March 2019
Contents: 8 Sessions, 181 Papers, 0 Presentations
Conference: Fifth Symposium on Novel Optoelectronic Detection Technology and Application 2018
Volume Number: 11023

Table of Contents

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Table of Contents

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  • Front Matter: Volume 11023
  • Optoelectronic Detection
  • Hyperspectral Detection
  • Laser Detection
  • Mirco-nano Detection
  • Space Detection
  • Applications
  • Erratum
Front Matter: Volume 11023
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Front Matter: Volume 11023
This PDF file contains the front matter associated with SPIE Proceedings Volume 11023, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.
Optoelectronic Detection
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Laser underwater acoustic detection technology based on vaporization mechanism
Sound signal excited by the interaction of laser and water has high range resolution and Marine anti-interference ability, it has broad application prospects in the area of underwater target detection. This paper deals with the problem of underwater target detection, the mechanism of laser-induced vaporization is studied, the experiment of laser vaporization is designed in this paper. The research results can provide reference for underwater target detection.
Research of image deblurring based on Tikhonov regularization
To deal with the shortcoming of the Tikhonov regularization in which the blurred image is extended with a zeros extension matrix. With careful analysis of the algorithms with Tikhonov regularization under zero boundary condition, a new extension matrix for the blurred image was proposed. The improved algorithm is in accord with the real image blurring process. Experimental results show that compared with other popular algorithms, the improved method performs favorably in solving the problem of the Average degradation and Gaussian degradation.
Quadrant uniformity calibration method for four quadrant photodetectors
Yang Xue, Lijing Li, Siyuan Wang
In laser guidance, the response uniformity of the four quadrant photodetector has an important influence on the guidance accuracy. Each quadrant photodetector needs to measure the response consistency between quadrants and be calibrated to the same response. In this paper, large area uniform laser irradiation is used to measure the inhomogeneity between detector quadrants. The gain compensation method is used to calibrate the inhomogeneity between detector quadrants. The main core of this method is that it needs to be able to modulate the intensity of the light source; the area of the light source can be modulated, and the maximum area should be able to completely cover the four photosensitive surfaces of the detector; the light source is a beam of uniform light power. In order to solve the problem that the uniform light effect is not ideal in traditional measurement methods such as spreading beam and frosted glass scattering, a beam expander and a beam homogenizer are used to realize the high uniformity of the uniform light spot. The detector is mounted on the single axis turntable and rotated around the optical axis to make the light received on the detector more uniform. This method realizes a four-quadrant detector for consistency calibration of quadrant response in the range of optical power of a certain wavelength. The method is simple, precise, stable and easy to implement.
Analysis and application of no-reference image quality assessment
In the No-Reference Image Quality Assessment, it is important to play a role in accurate positioning accuracy of the algorithm on image quality. Based on the current application of no reference image evaluation algorithm of some mainstream in a public database of research, including based on edge detection, based on energy distribution and based Pixel semaphore. Experiments show that the test accuracy of the algorithm based on edge detection can reach 95% in‘TID2013’data set and 91% in the traffic database and the speed of each picture is 0.002s, which is obviously better than the evaluation algorithm based on energy distribution and the evaluation algorithm based Pixel semaphore. It can be used as the basis of image evaluation for traffic monitoring system.
Measurement error of radiation gain of UV image intensifier
Shuning Yang, Ze Yao, Wujun Huang, et al.
The radiation gain of UV image intensifier is an important index to measure response capability of ultraviolet detector, thus its accurate measurement is necessary. This paper establishes radiation gain measurement method and device of ultraviolet image intensifier, The process of measuring the magnitude and Influencing factors for the measurement of ultraviolet radiation gain by the equipment were analyzed. And the error analysis of the measurement uncertainty of the device, The radiation gain measurement has an extended uncertainty of 9.59%, It can meet the requirements of high precision measurement of radiation gain of UV image intensifier. The research achievement can support the research and development of domestic ultraviolet detectors, thus providing an effective and accurate detection method for improving and promoting the technical performance of ultraviolet detectors.
Experiment and modelling study of the modulation performance in the graphene-Si heterojunction waveguide
Graphene-Si heterojunction devices have been widely studied in the field of photoelectric detection, solar cells and sensors areas. However, optical modulation devices based on graphene-Si heterojunction have been rarely reported. Herein, we analyze the photoelectric performance of the graphene-Si heterojunction at different laser powers. The Fermi level of the graphene can be tuned as the photo-excited holes in Si diffuse into the graphene. For the hybrid Si-graphene waveguide modulator, the maximum modulation efficiency of 279.3 dB/cm is achieved at 1550 nm by using finite element analysis method. We hope that the study of the graphene-Si heterojunction can provide a way for application in hybrid graphene-Si waveguide modulators.
Study on solution for eliminating the discharge in low-light-level image intensifier
Feng Liu, Bin Ren, Hong-li Shi, et al.
The discharge phenomenon in low-light-level image intensifier was proposed , and the occurs of the discharge in the tube was analysed. Starting from the structure of the tube, the quality and process environment to improve the manufacture were also prosed. Valuable solutions from tube structure to process controlling for eliminating it was proposed and was proved to be effective.
High-precision temperature control scheme and verification for space-borne infrared detectors
Shuang-shuang Zhu, Peng Zou, Mao-xin Song, et al.
In order to meet the application requirements of a space borne polarizing radiometer infrared band, a high-precision on-orbit temperature control scheme for the infrared detector combining active temperature control and passive temperature control is proposed. The infrared detector is installed on the heat sink copper block, and the temperature of heat sink copper block is controlled at -20°C~-30°C through the method of auxiliary cold plate + heat pipe thermal conduction. Combined with the infrared detector built-in three-level thermoelectric cooler, the photosensitive surface temperature of the infrared detector is cooled to below -60°C by a method of constant current driving. In order to ensure the measurement accuracy of infrared radiation polarization, the short-term temperature fluctuation of the photosensitive surface of the infrared detector is required to be less than 0.03°C/s. This article has designed the infrared detector temperature control scheme verification test, and actually measured the stability of infrared detector temperature and dark current. The results of the simulation and tests show that the range of infrared detector heat sink temperature is - 25±5°C, the range of infrared detector photosensitive surface temperature is -65°C ~ -75°C,the rate of short-term temperature change of the infrared detector photo-sensitive surface is better than 0.01°C/s, and the dark current fluctuation is less than 1.3pA. Satisfying the on-orbit high-precision polarization measurement requirements.
Method on multi-dimensional modulation in inter-satellite quantum communication
A multi-dimensional modulation scheme in inter-satellite quantum communication based on pulse position modulation and polarization encoding is put forward and designed. By this way we can send additional classical signal simultaneously when transmitting quantum signal. The basic principle of multi-dimensional modulation scheme is introduced. Simulation experiment is performed using Optisystem and Matlab simultaneously. The binary sequence before modulation and that after demodulation are compared and analyzed. The error bit rate, eye diagram and quality factor of classical optical date are obtained. Stabilities of classical optical signal during the transmission are tested. The results show that this multi-dimensional modulation scheme can decrease the numbers of information channels needed, increase information transmission efficiency and reduce the demands for power load systematic complexity in communication terminals. The proposed coexistence system is confirmed to be effective and applicable.
A helium mass spectrometry pressed integral leak detection technique for ultra-high vacuum devices
Min Li, Xiao-jun Yang, Ying-Ping He, et al.
Based on multi-weld seam of image intensifier tube, we have designed the leak detection platform for high vacuum electron devices, the experimental result show that Helium injection method’s minimum leakage rate is 10-11Pa·m3/s, and pressed integration method’s minimum leakage rate less than 10-11Pa·m3/s, and it is of positive significance to improve the life of the device.
Research of the electro-optical coupled equivalent circuit model for DFB laser based on ADS
Qinghe Zhuang, Junkai Yan, Xiaolong Liu, et al.
A novel electro-optical coupled equivalent circuit model for DFB lasers is presented in the Advanced Design System (ADS) computer-aided design environment, according to theoretical analysis for the input impedance equivalent circuit and the single-mode rate equations of distributed feedback (DFB) lasers. This model considers the influences of the input impedance and parasitic parameters of DFB laser modules, and which can emulate its voltage-current-light (V-I-L) static and dynamic response process. The simulation results show a good agreement with the measured results quoted from a literature on the direct current (DC) bias characteristics and small-signal frequency response characteristics. Therefore, the model provides great reference values in utilizing as numerical simulation and physical design for the DFB lasers as well as optoelectronic devices with its simple form, good numerical convergence and accurate calculation.
Experimental study of cat’s eye echoes detecting CCD damaged by 1064nm laser
In this paper, an experimental system for detecting the damage degree of the imaging optical system by using the cat's eye echo is established. The change mechanism of peak power of cat's eye echo is analyzed under different irradiation time. The relationship between the peak power of the echo and the damage degree of the CCD are established accordingly. The study found that the peak power of the cat's eyes echoes decrease dramatically, then increase significantly, then drop again, then increase again and decrease finally with the increase of the degree of damage of the CCD according to the damage order. In practical application, it is possible to judge the damage state of the enemies optoelectronic imaging equipment according to this rule.
Thermal function in silicon substrate of CCD induced by combined laser
This paper establishes a theoretical model of silicon substrate irradiated by the combined laser which is composed of a high-peak-power laser and a continuous laser. We use the finite element method to analyse the temperature of the silicon substrate irradiated by the combined laser. Then we compare the damage effect of the silicon substrate which is respectively irradiated by the combined laser and continuous laser, which is under the condition that the average power density of combined laser is equal to the continuous laser. The results show that the laser can melt the surface of silicon substrate in a short time, while the continuous laser can not achieve this effect. The combined laser damage in silicon substrate is stronger than continuous laser.
Hartmann wavefront sensor based on spherical reference wave
Common Hartmann wavefront sensor bases on planar reference wave which prevent it measure the aberration of spherical wave directly. When adjusting an optical system with a Hartmann wavefront sensor, the optical path should be collimated firstly. It will make the measurement more complicated and may bring new aberration. To solve the problem, a Hartmann wavefront sensor which bases on spherical reference wave is proposed. In this paper, we analyze the principles of the Hartmann wavefront sensor and verify its feasibility by numerical simulation. The simulation result shows that, on the condition of RMS=1λ(λ=0.6328μm), the relative RMS of the residual error of the reconstructed wavefront is under 8% when the detected wavefront is the 2~15th order Zernike aberration.
Study on the measurement system of laser beam quality for long distance propagation
Jie Fu, Baolin Du, Dezhao Zhou, et al.
In this paper, a testing system is introduced to monitor the beam quality of a laser beam propagating over a long distance. The system consists of a large aperture optical system, a high sensitivity receiving system, a fast signal processing circuit and so on. The laser beam quality propagating 10km can be tested, and the two-dimensional energy distribution, pre-mirror energy density, centroid coordinate and other parameters can be obtained.
Application of wave front distortion compensation technique in single-photon detection system
Jie Fu, Baolin Du, Dezhao Zhou, et al.
This paper presents a wave front distortion compensation technique applied to single photon ranging system. The key technologies in the design and the expected results are analyzed, which provides the design basis for the remote detection of the single photon ranging system.
An over-top tracking test system for electro-optical detection device
Shaofei Wang, Fei Xie, Dezhao Zhou, et al.
In this paper, an over-top tracking test system for electro-optical detection device is designed, which provides an overtop test environment for electro-optical detection device by using a two-dimensional motion turntable covering the target source of the infrared and visible light bands in a rolling and pitching shafting system. The electro-optical detection device for two-frame configuration provides over-top tracking[1] function and performance testing and verification conditions.
Design of a portable infrared/visible composite target simulator
Shaofei Wang, Leili Hu, Dezhao Zhou, et al.
This paper presents a portable infrared/visible composite target simulator design configuration. The system adopts reflective optical design, through the combination of blackbody and visible light source system design and a variety of target plate, it can provide 0.4μm~12μm band simulation target, with parallel difference better than 10″ and 200mm optical aperture. It provides a variety of quasi-direct simulation targets for infrared and visible performance and dynamic tracking test of photoelectric detection equipment.
MTF testing device for photoelectric imaging system based on slit tilting method
Dengkui Kang, Hongru Yang, Changlu Jiang, et al.
Modulation transfer function (MTF) is one of significant parameters for designing and evaluating an photoelectric imaging system. As the traditional MTF measurement algorithm cannot meet the need of discrete sampling characteristics for photoelectric system, an automatic interpolaton and sub-pixel matching algorithm based on slit tilting method is proposed.Through the least-square analysis of line spread function (LSF),the tilting angle can be automatically calculated, and interpolaton of sub-pixel data can be precisely reconstructed. The noise of oscillation can be effectively restrained by a hanning window function. A device composed of target generator system, off-axis reflective collimator, mechanical adjustment, electrical control system, video acquisition module and comprehensive software was setup. The validity of the method was verified by experiments. The repeatability reached 0.007。
Research of the image restoration algorithm based on boundary pre-processing in the space domain and fast computing in the frequency domain
Fang Wang, Qinxiao Liu, Dongxia Hu, et al.
On a high power solid laser facility, the wavefront coding (WFC) technology has been adopted to obtain 3m-13m over-long depth of field in an array optical components defect detection system[1]; The lack of the boundary information due to the sudden boundary truncation will cause the ringing effect in the image restoration process. By using the theory of the boundary condition s(BCs), an image enlarged by the different boundary hypothesis can be given; The frequency filtering has been used to find the restored result. The frequency property of the enlarged image and the effect to the boundary of the restored image are analyzed. Effectiveness and speediness of the proposed method are demonstrated by experiment results, which can give excellent deconvolution and noise suppression restored image and reduce the boundary ringing effect under the reflective boundary conditions in a wave-front coding (WFC) system. The experiment shows the proposed algorithm can give satisfactory restoration results on the long depth of field array optical components defect detection system[1] .
Dynamic infrared target camouflage effect evaluation
Jia-ju Ying, Dong-sheng Wu, Bing Zhou, et al.
Dynamic infrared camouflage can need to change according to the background, and quickly from a state of camouflage into another state of camouflage. The image characteristics of various infrared camouflage states weak correlation, can make the infrared surveillance and tracking, target infrared characteristics of the real difficulty of the guidance system, unable to complete the target reconnaissance and combat, so as to improve the battlefield survivability of the target. According to different background conditions, infrared camouflage algorithm is adopted to realize infrared camouflage for equipment, so that equipment and background can be integrated. The evaluation of camouflage effect needs to be carried out through corresponding methods. Based on the principles of evaluation index selection, and given to evaluation object, evaluation purpose and evaluation method, constructs the evaluation index system, comprehensive selection of brightness contrast and color features, texture features three evaluation indexes. Combined with the specific test, the infrared camouflage effect was evaluated, the indicators were analyzed, and all the indicators were comprehensively analyzed according to the weight value. Finally, the optimal state for the comprehensive evaluation of the camouflage effect was given.
Glass bottle cap gap width detection combined with transmission lighting system design based on machine vision
Guangmang Cui, Jufeng Zhao, Liyao Zhu, et al.
Combined with the design and construction of transmission lighting system, the machine vision detection scheme is proposed for bottle cap gap width inspection of industrial production line. With the consideration of the reflective properties of glass bottle material, the transmission lighting method using white LED array light source is designed.. It could avoid the disturbance on the detection algorithm caused by the nonuniformity of the imaging region. The vision detection algorithm is developed by using automatic bottle cap region search method and edge detection by seed growing. The upper and bottom edge line position is extracted precisely and the real bottle cap gap width is calculated by image pixel physical size calibration. The real experimental imaging system is setup and the experimental results demonstrate that the presented machine vision detection scheme could realize high precision bottle cap sealing gap width detection with detection precision as 0.01mm. The vision algorithm has high accuracy and the processing speed could satisfy the production line task requirements for bottle cap detection.
Propagation of circularly symmetric partial coherent ultraviolet beams in atmospheric turbulence
Feng Shi, Hong Lv, Xudong Liu
Spatial coherence of optical fields determines the propagation property of a light beam. In this paper, we study the atmospheric turbulence effect on ultraviolet(UV) beams. The degree of coherence of the UV beam is modelled as a fractional multi-Gaussian correlated Schell function with rotational symmetry. Results show that the spectral density of the UV beam can retain its shape over 1 km in weak and moderate atmosphere turbulence. The beam spread and slow decay of spectral density distribution of the UV would be beneficial for non-line-of-sight UV communications.
Ameliorated method of intensity correlation imaging with coherent light illumination
Chong Li, Xin Gao, Xi-yu Li, et al.
In order to study the influence of variation of the active laser coherence on the intensity correlation imaging, the coherence factor is introduced by the generalized Van Citter-Zernike theorem. Establishing the intensity correlation imaging model based on the variation of coherence, a laboratory experimental platform is designed. Hence, the effect of coherence on spectral modulus can be calculated by using the new model. Then, different phase retrieval algorithms are used to restore the images. The experimental results show that: coherence variation has an effect on the calculated spectral modulus, and the coherence factor can eliminate the effect to a certain extent. The intensity correlation imaging model based on coherence variation can better restore target images, which proved the correctness of the model. Image quality of prior information iteration algorithm is higher than that of hybrid input and output algorithm. The signal-to-noise ratio of reconstructed image is measured to up to be 5.3 dB.
Errors analysis of laser relative navigation for fixed wing aircraft landing
Jingting Su, Yang Xie, Qi Zhou
A high precision measuring device is required during the fixed-wing aircraft landing. In order to improve accuracy of laser scanning system, a scanning measurement model is established to carry out error analysis. The measurement error simulation is carried out for two cases without sea-wave disturbance and sea-wave disturbance, and the variation law of angle measurement error is obtained. The results show that the angle error becomes lager as the plane gets closer and closer to the landing point, and the error reaches the maximum when the plane landed. The wave disturbance will cause a small range of jitter in error curve, and the amplitude will increase slightly. The result provides a theoretical reference for the compensation correction of laser scanning measurement system.
Field studies of polarized reflectance characteristics of natural and manmade objects
Min Yang, Wen-Bin Xu, Jun-Wei Li, et al.
The sunlight reflected from object surfaces is partly polarized, which is the useful information for polarized remote sensing. Therefore, it is important to perform the field polarization measurement, which can not only obtain the true physical polarization characteristics of object, but also be used to match with the polarimetric measured results from the airborne observation. However, there is no research concern the difference of polarized reflectance property between natural background and manmade objects in the natural environment. In this paper, we measure Visible-Near Infrared spectral polarized reflectance properties of two natural surfaces (soil and grass) and six manmade objects (cement and five painted materials) over the hemisphere directions in the field. The measurements are carried out with an automatic polarimetric spectrometer equipped with the goniometer. The results indicate that the polarization reflectance of manmade objects and natural background show the obvious anisotropic characteristics. The soil and grass produce the maximum reflectance value in the backscattering direction, which is opposite to the manmade objects. The polarized reflectance factor of manmade object is much greater than natural background, which can be used to effectively distinguish the object and the natural background. Our study has a great potential for target detection and identification in the field.
High-density interpolation using in optimizing correlated color temperature calculation
Xipeng Qiu, Yingying Xu, Chi Chen, et al.
The color temperature and the correlated color temperature are important parameters in optical radiation measurement. In practical application, it has been a general indicator in representing illuminant color and the quality of spectrum. Starting with the source spectrum, the method via comparison has high precision, as well as a complicated process. A simplified arithmetic is needed to guarantee the veracity. Analyzing the model preliminarily on the basis of iso-color temperature line parameter given by CIE 1931, a new model can be built according to spectral power distribution. It takes steps by color temperature directly on computer programming, aiming at increasing the density of iso-color temperature line and homogeneity, and then, calculating the impact to the uncertainty of the result. By comparing with the other classical methods, it proves that high density interpolation is a programming method on calculating CCT with lesser error and better performance.
Phase noise of RF signal in photonic link
RF photonic link can provide significant benefits in transmitting and distributing RF signals to many separating stations by optical fiber. However, phase noise of transmitted RF signal in electrical-optical-electrical conversions is generally deteriorated by related optical noise. In this paper, a theoretical model about phase noise of RF photonic link is built, and the expressions and characteristics about phase noise are investigated. In the RF photonic link, phase noise is investigated for 100MHz RF signal. The experimental results can agree with the theoretical analysis.
Fusion positioning method of optical measuring equipment and GNSS
In order to expand the scope of exterior trajectory measurement system, it is required to make full use of various heterologous measuring elements to establish a joint positioning model with multi-system measurement information to make up the traditional positioning method. Meanwhile, there must be many redundant observations in the tracking measurement. It will improve the accuracy and continuity of target tracking measurement and optimize the comprehensive measurement level of the measurement and control system and unit efficiency by making rational use of these redundant measurements and processing with data fusion algorithm. The measuring angle and range of optical measuring unit and constraint equation of GNSS pseudo range measurement information were discussed in this paper. Optical and GNSS joint measurement model was established. The least square solution of this nonlinear equation was obtained with Newton iteration method. Finally, simulation data was used to verify the result. The result shows that the target position can be calculated by making use of the measured information of optical and GNSS unit in the minimum positioning condition, and the accuracy of fusion calculation result will improve correspondingly when there are many redundant measurement elements.
Infrared and ICMOS image fusion camera
Night vision technologies have been used in military and civilian monitor wildly. In this paper, an image fusion camera based on Infrared FPA, ICMOS and FPGA is designed. First, image acquisition module consist of bias voltage, AD circuits and optical system is built. The MCP in front of the CMOS ensures the gain up to 104. Then, Verilog is written to drive these two sensors, pre-proceed the images data and push them into LPDDR. Moreover, we propose a fully parallel algorithm to fuse the images in real time using gradient. This algorithm neither needs iteration nor morphology, so it dose not consume the band width of LPDDR. Finally, video is output in PAL format.
A handheld high-resolution low-light camera
Solid low-light imaging device is an important part of night vision, which has the advantage of high resolution, high contrast and small size, and it can work 24 hours. A handheld high-resolution low-light camera is proposed based on the characteristics of GSENSE400BSI CMOS image sensor in this paper. The camera includes CMOS driver, image correction, cache, low-light image enhancement and ultra-clear format encoding, implemented on an FPGA-based hardware platform. And the camera structure is optimized designed to realize the handheld operation. Finally, the experiments show that the low-illuminance camera display the details of the target clearly under 10-2 lx illumination, with an effective display resolution of 2048×2048@60fps.
Recognition of thermal infrared oil tank targets based on blotch detection and clustering and SVM classification
This paper proposes a method for detecting oil tank targets that combines improved blotch feature detection and SVM sample learning in order to address deficiencies in the recognition of oil tank targets in thermal infrared remote sensing images due to indistinct edge information, high noise level, and small dimensions. First of all, initial detection was conducted on the basis of blotch features and mass features. Then the features of oil tank targets and an optimal combination of classification features were generated from sample learning. Finally oil tank targets were detected through classification based on SVM sample learning. The results of the experiment show that: 1) by setting appropriate parameters, this method combines blotch features and textural features for the extraction of a more comprehensive range of TIR oil tank features that can achieve the effective detection of oil tank targets; 2) based on the detection of blotch targets, this method can filter out false targets with relatively high accuracy and is capable of more stable and efficient recognition of Type #1 and Type #2 targets.
Comparison of chemometrics method on K detection in soil using laser induced breakdown spectroscopy
Chengxu Lü, Xunpeng Jiang, Yanwei Yuan, et al.
Potassium detection in the soil is of significant importance for agricultural industry. In this paper, chemometrics methods of artificial neural networks (ANN) and partial least squares (PLS) were comparatively used to detect K in the soil with laser induced breakdown spectroscopy (LIBS). In total, 12 certified reference soils and 17 simulated soil samples with the K concentration of 0.1~3.3% were prepared. LIBS spectra at the wavelength of 723.62~808.24 nm were collected, and then analyzed with ANN and PLS method. The PLS model presented the result of R2 val=0.92 and RMSEV=0.26, the ANN model presented the result of R2 val=0.82 and RMSEV=0.40. ANN model showed under-fitting and the PLS model performed a better RPD than that of ANN. This demonstrated that the linear PLS model is capable to determinate K concentration in the soil using LIBS.
Simulation research on optical axis drift of Cassegrain system in micro-vibration environment
Shengwei Chi, Lei Zhu, Ming Ji, et al.
The vibration environment of the internal opto-machinal system of the electro-optical pod is different from the external vibration environment and needs to be accurately defined. Based on the detailed analysis of the vibration source distribution and response bandwidth of the airborne electro-optical system, the Cassegrain Opto-mechanical System is taken as the research object, and the complete analysis process is established from the original environmental excitation. The equivalent vibration algorithm is used to determine the micro-vibration conditions. The finite element detail model of the connection method is used for dynamic response. At the same time, based on the simulation model optomechanical system, an optical axis drift analysis method based on feature point correlation and response extremum judgment is proposed. The relationship between the displacement mode and the amount of drift of the optical axis is obtained.
A 320 x 256 readout circuit with wide dynamic range and high injection efficiency
Ding Ma, Xiang-yang Li, Yan Zhang, et al.
A 320×256 readout integrated circuit (ROIC) with a pixel pitch of 30μm is presented for solar-blind AlGaN ultraviolet focal array plane (FPA). Capacitor feedback transimpendance amplifier (CTIA) has been selected as the input structure of the ROIC because of its excellent performance. A novel cascade amplifier with a symmetrical differential input stage is designed for input stage of CTIA, and an ultra-low capacitance with a value of 10fF is in the feedback loop of the amplifier as integral capacitor. Furthermore, the ROIC read out in a rolling shutter mode by using cascade D flip-flops. The ROIC has been fabricated 0.35μm 2P4M mixed signal CMOS process and interfaced with AlGaN solar-blind ultraviolet focal array plane (UVFPA). The test result shows that 320×256 AlGaN UVFPA has a wide dynamic range of 88.2dB with 5V power supply and has a high injection efficiency of 98.2%.
Multi-channel Interferometric SAR/GMTI method for solving the radial velocity ambiguity of moving target
To solve the problem of velocity ambiguity caused by over high azimuth velocity in the conventional SAR/GMTI system, a kind of multi-channel interferometric SAR/GMTI scheme solving the radial velocity ambiguity of moving target is presented in this paper. This method sets up four non-uniformly interval receiving channels and designs each channel spacing reasonably. Interferometric cancellation is carried out on the sub image of two echo signal, then it can get two velocity sets, and the intersection of the two sets is the correct estimation of the target velocity. Thus, the problem of velocity ambiguity is solved effectively and the radial velocity of the target is estimated correctly. Analysis and computer simulation demonstrates the validity of the method.
Optical fiber gas sensor based on organic polymer
Zinan Wu, Donglin Tang, Yanyan Wang, et al.
This paper proposed a method of optical fiber gas sensing which based on the detection of sensitive phase of light wave combined with organic polymers, simultaneously, the experimental verification was given. We found that the refractive index of the organic polymer will change accompanied with the change of concentrations of acid gases that act with the organic polymer. So, we put the organic polymer film into the optical fiber Fabry-Perot (F-P) cavity and analyze the spectral characteristics of the output of the optical fiber F-P cavity, then, we realize the hydrogen sulfide gas sensing. Experimental results show that the refractive index of organic polymer decreasing when the concentration of the gas under the test is increasing. At low concentration, a system resolution record of 3.0455 ~ 4.7777 × 10−5m/%VOL is obtained, phase sensitivity is found to be 1.94 ×102 rad/%VOL and concentration resolution is found to be 5.15 x 10-3 ppm. Through this test, we proved the possibility by using organic polymer to realize the sensing of gas. In general, this scheme can be applied to high-precision measurement of carbon dioxide, hydrogen sulfide and other gases in the petrochemical field.
Spectrum reconstruction algorithm for multi-channel non-uniformly sampled SAR and error analysis
The SAR DPCMAB(Displaced Phase Centers Multiple Azimuth Beams mode) can increase the sampling rate in the azimuth direction,whereas, it brings the problem of non-uniform sampling. Using spectrum reconstruction algorithm can regain the spectrum of uniform sampling signal. However, as the influence of interferential factors produced during the operation of SAR system, such as channel characteristics inconsistency, sampling time deviation, random noise etc, spectrum noise is appended to the reconstruction spectrum resulting in the loss of reconstruction accuracy. The paper analyses the relationship between interference factors and reconstruction error by researching spectrum reconstruction of non-uniformly sampled LFM signals affected by interferential factors. Reconstructed spectrum influenced by interferential factors is obtained in the simulation. Further more, we present the relationship curve between spectral bias and interference factors. The simulation results show that the reconstruction errors grow linearly with the enhance of the interferential factors and approach to the spectral bias of non-uniformly sampled signal finally.
A fast and accurate moving target detection method
This paper proposes a significant moving target detection method combining time difference and optical flow field filter for scenes with complex backgrounds such as streets and traffic intersections. Firstly, the gradation change region of the sequence image is obtained by using the cumulative frame difference, then the Lucas-Kanade optical flow algorithm is introduced to obtain the optical flow field of the gray-scale change region. Finally, the optical flow time filter is used to filter the interference motion in the image background. The method can not only detect the motion area quickly and accurately, but also distinguish the spurious interference motion from the salient target (such as people, cars, etc.). So it detects the moving target in a complex background easily.
Polarization test of VISNIR remote sensors based on Fourier series fitting method
The polarization sensitivity is an important factor of quantification of remote sensing information, which is used to evaluate polarization response of remote sensors. In this paper, the white light laser, polarizing film, and the beam expander system make up the polarization measurement system. And then the polarization test is accomplished. Unlike the traditional analysis, this paper proposed a method of Fourier series fitting to analyze the polarization test data. Compared with the cosine function fit, Fourier series fitting is closer to the real data, and the influence of natural light and elliptic polarized light. And it has advantage in the error analysis of polarization test and can help improve polarization test precision. At last, the errors of polarization measurement is analyzed.
Research on single event upset effect of CMOS image sensor for space application
Bo Wang, Li Xu, Ying Pan, et al.
CMOS image sensor (CIS) is widely applied to remote sensing, spatial trend monitoring, spacecraft attitude control and aerospace engineering, which is across the key device of the platform technology of spacecraft and payload technology. However, Due to the complex radiation environment consist of Galactic cosmic rays, solar particles, and proton or electron from earth capture belts, CIS is inherently sensitive to single event effects, which is the bottleneck of space applications. In this study, 8T-global shutter CIS was taken as experimental sample. The test results show different function module of CIS occurred single event upset (SEU) leads to different abnormal image mode, such as the output image of "always zero", several adjacent column output anomalies, the whole image messy code. We will analyze microcosmic process of ionization charge generation, diffusion, collection, analyze macroscopic image anomaly, obtains the single event effect sensitive area of the device, deeply discusses the single event effect of CIS and its damage mechanism. The research results will enrich the 8T-global shutter CIS radiation effects theory, as well as there are provide scientific basis for anti-radiation design, test method and evaluation technology.
MCP gain and its influence on ultraviolet photon counting imaging detectors
Yong-an Liu, Neng Xu, Feng Shi, et al.
Micro-channel Plates(MCPs) are an important part of ultraviolet photon counting imaging detectors. They can intensify single particles or photons by the multiplication of electrons via secondary emission.Thus, the MCP gain has an very important influence on the performance of ultraviolet photon counting imaging detectors. In this article, influence of MCP gain on decoding accuracy is studied by using Monte Carlo method. Simulation results show that decoding error is large when MCP gain is low,and MCPs shoud have at least 106 gain to ensure accurate decoding. At the same time, influence of MCP gain on decoding error was tested by using ultraviolet photon counting imaging system based on TWA(Tetra Wedge Anode,TWA). Experimental results are consistent with the theoretical analysis and simulation.
Approach for prediction of ship angular deformation based on distributed local inertial measurement units
The coordinate reference misalignment caused by ship angular deformation is an important factor affecting the operational performance of shipborne weapons and equipment. Based on the local inertial measurement units (IMUs) distributed on the ship and the deformation law of ship mechanics, the whole ship deformation prediction can be realized. The influence of local reference number and installation location on the accuracy of deformation prediction is studied in this paper. The simulation results show that when the installation position of the ship local IMU can better reflect the ship vibration model characteristics, four sets of local inertial reference can be used to predict the angular deformation at any point of the whole ship by the least square estimation method. The interpolation prediction error is less than 2.5″ (1σ), and the extension prediction error is less than 5″ (1σ).
Linear avalanche photodetector based on CMOS process
Guohao Ju, Zhengxi Cheng, Yongping Chen
A linear avalanche photodetector based on standard CMOS process is designed and fabricated. The doping dose of p-layer of the device with typical n+-p-π-p+ epitaxial structure is 1.82×1012/cm2, and the depth of the doping peak concentration is 2.1 μm. The dark current, photocurrent, spectral response and excess noise factor are measured. The punch-through voltage is about 60 V, the breakdown voltage is about 147 V. The spectral response range is 400~1100 nm, and the peak response wavelength is about 850 nm, the peak response wavelength is in the near-infrared range. When the gain is 50, the reverse bias voltage is about 143.3 V, and excess noise factor is about 4.35. The results show that the device has an excellent performance of visible light detection.
Intrusion location method of distributed fiber optic for oil and gas gathering pipelines
In order to detect external intrusion which threatens the safety of oil-gas gathering pipelines in time, it is necessary to monitor the operation status of pipelines in real time. A distributed fiber optic perturbation sensing principle based on the Mach-Zehnder (M-Z) interferometer was described. The experimental device was set up to monitor the intrusion signal along the optical fiber. An improved cross correlation algorithm was used to locate intrusion, which processed piecewise signal. Experiments were completed on the disturbance's optic fiber with a total length of 10.1km. The system monitored the external intrusion signal and correctly displayed the position in real time. The average positioning error 68.12m is achieved. The positioning error is reduced about 43% over the conventional method. The proposed method can effectively improve the positioning accuracy of the external intrusion signal.
Design and theory analysis of infrared detector
In order to achieve the purpose of far detective distance、relatively high anti-jamming performance, the new missile requirements of infrared detector with high detectivity and low signal-to-noise(SNR), fast cooling-down. Based on the mechanism of infrared detector and design theory, combining technology practice, the indium antimonide(InSb) detector chip passivation film and the antireflection coating design and manufacturing are analyzed, while the Principe of multi-layer structure of the fast cooling-down cooler tubes are analyzed. Its detectivity is beyond 3x1010 cm·Hz1/2·W-1, the current responsivity over 0.24A/W, the impedance at zero bias voltage beyond 500KΩ, cooling-down time less than 3 seconds. The specifications meet the requirement for air-defense missile, and out-door the infrared detector has been demonstrated successfully. It can realize the requirement of missile detection distance is greater than 5km.
Spatio-temporal super-resolution implementation based on camera array
Multi video super-resolution algorithms reconstruct high spatio-temporal resolution video by exploiting complementary information in multiple low-resolution video sequences. Aiming at improving spatio-temporal resolution of video for real-world applications, an algorithm is proposed using Maximum Posterior Likelihood - Markov Random Field (MAP-MRF) and implemented on camera array. Compared with the current algorithms for super-resolution reconstruction, the suggested algorithm is advantageous in keeping the edge sharpness and detailed texture, and robust against the noises. The experimental result has confirmed the effectiveness of the proposed method under the practical conditions such as large displacement and motion aliasing.
Beaconless acquisition tracking and pointing scheme of satellite optical communication in multi-layer satellite networks
Weiqi Chen, Qi Zhang, Xiangjun Xin, et al.
Aiming at the problem of lightweight and miniaturization of satellite optical communication terminals and intersatellite optical communication in multi-layer satellite networks, The beaconless light tracking and acquisition technology in satellite optical communication is researched and analyzed. The link margin of the satellite laser link under direct detection mode is analyzed , the track and the capture process is designed, the influence of satellite platform attitude error, inter-satellite link communication distance and other factors on capture time and capture probability are simulated and analyzed. The scheme designed uses the active side to emit signal light to scan the FOU, and the passive side uses the capture. The way the detector gaze is captured, ie the gaze-scan capture method. The research shows that in the designed multi-layer satellite network optical communication scenario, the acquisition time of GEO satellite to MEO satellite and GEO satellite to LEO satellite communication is 2034 seconds and 351 seconds respectively, and the capture probability is 95.28% and 99.99% respectively. The acquisition time of MEO satellite and LEO satellite communication is 216 seconds, and the probability of capture is 87.32%, which can meet the requirements of optical communication links of different orbit satellites in multi-layer satellite networks.
Research on the influence of local oscillator power on signal-to-noise ratio of system under balance detection mode in 1.55um laser coherent detection system
Ce Li, Yu Han, Haixia Chen, et al.
In order to explore the effect of local oscillator optical power on the signal-to-noise ratio (SNR) of the system under the balanced detection method and the traditional single-channel detection mode in the laser coherent detection system. The numerical simulation analysis of the SNR of the coherent detection system is realized by using the local oscillator power.The self-built laser coherent detection platform is used to explore the influence of the local oscillator power on the system measurement range and SNR in the single-channel detection and dual-channel balance detection under the balanced detection mode. The results showed that: in coherent detection systems, balanced detection has certain advantages over single-channel detection. After calculation, in the detection range of 3km, the measured SNR in the balanced detection mode is higher than the single-channel detection SNR by 2.1.This conclusion has certain reference significance for improving the detection effect of the coherent detection system.
Image reconstruction algorithm analysis of spatially modulated full polarization imaging system
Song Ye, Hao-Fang Yan, Xiao-Bing Sun, et al.
The spatially modulated full polarization imaging system can acquire target images and polarization information by using spatial carrier fringes to encode full Stokes parameters in a single interference image. This polarization detecting technology uses a Savart Plate (SP) as a spatial modulation module encodes two-dimensional Stokes parameters S0~S3 and the information of four Stokes quantities can be obtained by a single detection. The principle and mathematical model of this system is analyzed in details, and the image reconstruction method is also presented. Two different frequency domain filtering algorithms for demodulation are applied to reconstruct images in numerical simulation and laboratory experiment. The frequency domain algorithm based on two-dimensional Gauss low-pass filter does not have ringing, it has obvious advantages in image reconstruction. The measured data of polarized light and depolarized light from spatially modulated full polarization imaging system is demodulated by optimal algorithm. Reconstruction results show the polarization degree of depolarization light is less than 5%, which the one of polarized light generated by a polarizer is approximate to 100%. These results are coincident with the theoretical prediction well, which verify the feasibility and validity of the algorithm.
Pulsed thermography for the NDT of honeycomb composite
Dapeng Chen, Jian Zhou, Zuoming Sun, et al.
Honeycomb sandwich Composite has wide applications in manufacture, such as aircraft, automobile, rail transit, and so on, due to its special advantages. However, defects always exist in the honeycomb composite during manufacturing and in-service period, liquid ingress and debondings are the most typical defects. In this paper, according to the NDT problem for this kind of material, Pulsed thermography is applied, theoretical model of heat conduction for the defect detection under an instantaneous heat source is analyzed; Several kinds of honeycomb composite specimen is designed for the two typical defects detection; Pulsed thermography is applied on the specimens and the defects are revealed by the thermal images sequence processing. Furthermore, by analyzing the logarithmic temperature decreasing curves can distinguish different types of liquids under the skin. Results show that Pulsed thermography has advantages for the NDT of honeycomb composite.
Design and test of long-wave infrared dynamic scene projector based on IR-CRT
The infrared dynamic scene projector is a key component of the infrared imaging seeker semi-physical simulation system. Aiming at the long-wave infrared imaging seeker system, the design idea of long-wave infrared dynamic scene projector with IR-CRT as the core device was proposed. The working principle of IR-CRT was introduced. The optical collimation system was designed. The key parameters such as resolution, distortion, simulated temperature range and uniformity were tested. The dynamic scene projector had been successfully applied to infrared imaging seeker. The semi-physical simulation system had verified the static and dynamic tracking performance of the infrared imaging seeker, which met the requirements of product use, and promoted the product development process.
Towards meat quality determination on miniaturized spectral imaging and computer vision technology
Shuyang Liu, Hanyou Tian, Chen Zhang, et al.
Meat freshness degree is an important parameter while evaluating the quality and the price of the meat. Traditional method needs too long time to evaluate the meat on line in the meat slaughterhouse. To improve this situation, a system with potentiality of integrating miniaturized spectral camera is developed and tested in the practical situation. The results show that the system does not only improve the efficiency of meat grade evaluation procedure but also improve the accuracy compared with the method applied now.
Gravity load effect analysis and modal analysis of 1.2meter terahertz antenna for near-field holographic measurement
In this paper, the finite element parameterized model of 1.2 meter terahertz antenna is established for near-field holographic measurement. The structure of 1.2m antenna, which consists of reflector body and tower base, is developed to a prototype of the 5-m Dome A Terahertz Explorer (DATE5). The reflector is made of carbon fiber-reinforced plastics, and tower base is made of steel. For the evaluation of the antenna performances, the gravity load effects of 1.2m antenna have been analyzed by the model. The numerical analysis results show that reflector surface RMS errors due to gravity load decrease with the increase of elevation angle, and the ranges of values of the surface RMS errors are from 0.14μm, to 0.81μm, which has been met the performance requirements of 1.2m antenna. Moreover, the mode shapes and the eigenfrequencies are also studied. The results suggest that the trends of the dependence of first three orders eigenfrequency upon elevation angles are well agreement with those of DATE5: the eigenfrequencies of the first and second orders of the model also decrease with the increase of elevation angle, while the eigenfrequencies of the third order increase with the increase of elevation angle.
Fusion technology for polarization-maintaining photonic crystal fiber-optic gyroscope
Parameters affected the splicing loss and polarization cross-coupling during fusion splicing between Polarization-Maintaining Photonic Crystal Fiber (PM-PCF) and conventional Polarization-Maintaining Fiber (PMF) were investigated. The influence of loss and polarization cross-coupling to the phase error of the fiber optical gyroscope (FOG) is calculated and tested. At last, an efficient and simple method of fusion splicing PM-PCF and PMF with a low loss of 0.65 dB in experiment is reported.
IR imaging pre-processing system design based on Zynq-7000
An Infrared Imaging Pretreatment System was designed based on Xilinx Zynq-7000 Extensible Processing Platform (EPP). Zynq-7000 integrate a dual-core ARM Cortex-A9 based processing system (PS) and programmable logic (PL) in a single device. In this design, PL was developed for IRFPA video signal acquisition, and used VIDEO_IN, VIDEO_OUT, AXI-VDMA IP core to build high speed data channel between PS and PL. PS was developed for Imaging Pretreatment such as Non-uniformity correction, Blind pixels compensation and Image enhancement, using DDR3 for PS’ external memory and PL for Camera Link/PAL video output. It’s optimized for powerful, high real-time, small size, low-power and high reliability, to reach the goal of mass production in work.
Multi-spectral image level-by-level registration algorithm based on A-KAZE feature
Hongyu Li, Bin Xue, Yongfang Li, et al.
Aiming at the problem that he gray level of different spectral images varies greatly and the traditional feature extraction algorithm is difficult to maintain the local precision and edge detail of the image, a multi-channel multi-spectral image registration method based on A-KAZE algorithm. In the registration process, the Fast Explicit Diffusion (FED) numerical analysis framework is used to solve the nonlinear diffusion filter equation, and the nonlinear scale space is constructed. The feature points are obtained by calculating the Hessian matrix of each pixel; The invariant image feature vectors are constructed by the Modified-Local Difference Binary (M-LDB) descriptor. Then, the feature vectors are matched by KNN using Hamming distance, and the mismatched points are eliminated by M-estimator Sample Consensus (MSAC). Finally, the transformation matrix is calculated based on projection transformation model. For multi-channel multi-spectral images, the optimal registration route is calculated by level-by-level registration method, and the image registration is realized by registration strategy and transformation matrix. Multispectral phenological observation data were selected to verify the image registration effect of the algorithm, and compared with SIFT, SURF, KAZE algorithm. Experimental results show that this method can achieve sub-pixel registration accuracy on any two images, and has strong robustness and faster speed.
The application of industrial CO monitoring based on infrared imaging molecular filter technology
The development of imaging equipments for pollutant gases monitoring is concerned not only to efficient resource utilization but also to environment protection. CO is extremely harmful although its concentration is relatively low among industrial waste gases, which leads to a challenge for traditional spectral remote sensing methods. The infrared imaging molecular filter show great advantage in extracting target gas infrared spectrum signal and restraining radiation interference from environmental background and other gases due to its characteristics of the comb like transmission spectrum with ultra narrow band. In this paper, remote sensing and monitoring of industrial CO emissions based on infrared imaging molecular filter technology is carried out. real-time images of CO gas are also obtained. The experimental results show that this scheme provides a good solution for remote sensing and monitoring of industrial waste gas by using an imaging method.
Analysis of SNR in 4-transistor backside-illuminated CMOS image sensor
Sheng-kai Wang, Chuan Jin, Kai Qiao, et al.
Based on the study of working principle and making process of 4-transistor Backside-illuminated CMOS (4T BSI-CMOS), Signal-to-noise ratio (SNR) model are established and quantitative calculating formula is derived. In addition, factors of influencing SNR are analyzed. Two methods are presented to enhance the SNR, the one is optimizing structure of 4T BSI-CMOS image sensor to strengthen the signal and the other one is correlated double sampling to decrease fixed pattern noise (FPN). These results serve as useful guidelines to enhance the SNR of 4T BSI-CMOS and improve the image quality.
Quick search and threat evaluation algorithm against sea-skimming IR small targets
Hong-xing Ma, Xin-jian Wu, Zhi-fang Min, et al.
Air defense and anti-missile operation usually demands the EO device to quickly detect the sea-skimming missile in a given area. Because the small sea-skimming target usually features low brightness, small size and susceptible to interference from the sea horizon and sea surface clutter. Therefore, a quick search and threat evaluation algorithm is proposed against sea-skimming small targets. First, statistic row mean value and gradient are worked out, and the sea horizon is fitted by means of least square criterion. The background shall be suppressed by using morphological factor and the image shall be binarized by using self-adaptive threshold. Finally, statistic suspicious target features are carried out for threat evaluation of these suspicious targets, sea clutter and sea horizon interference are eliminated and the high priority threat is picked up.
Application of SIFT feature vector matching algorithm in binocular stereo vision system
Jing Dong, Wei Liu, Yun Zhu
Stereo vision matching is to search the corresponding relation of one spatial object observed from different angles in the projected image, and obtain the parallax image depending on the deviation (parallax is the geometric distance between different points projected from the same spatial point on different image. In a parallel binocular stereo vision system, two cameras have the same focal length and parallel imaging planes, so there is no rotation and scale conversion for images obtained by two cameras. SIFT binocular stereo vision system does not need multi-scale conversion and coordinate axis rotation, therefore the algorithm is simplified and the fault tolerance for SIFT target matching is maintained.
A dual-band infrared fusion ship target extraction method based on Markov random field model
The marine and air background images obtained by a single shipborne infrared sensor often have problems such as low contrast between target and background, high noise, and lack of complete target details, which bring great difficulty to the extraction of ship targets. This paper analyzes the basic features of the ship target in medium/long wave infrared image and proposes the basic model of ship target extraction based on the Markov Random Field (MRF) theory. According to the two-band target and background prior probability distribution, the energy minimization framework is added. Regional believable propagation (BP) algorithm is used to perform global optimization of the model, and image segmentation label is estimated according to MAP criteria. The experimental results show that the fusion extraction algorithm can retain the effective components in the original dual-band infrared image, and the extraction efficiency and accuracy are higher.
A new method of evaluation of x-ray pulsar detector sensitivity
Hu-jun Hu, Song Juan, Si-pei Shao, et al.
Detection sensitivity is an important indicator of the X-ray pulsar detector. In order to achieve the accuratesensitivity of the detector, a new method of calculate detection sensitivity is proposed calculation. Combining with the characteristics of X-ray pulsar radiation spectrum and detector spectral,classic pulse accumulation model is corrected.A new signal to noise ratio (SNR) calculation formula is deduced by using the new pulse accumulation model.Constructing a new variable Z, which has close relationship with SNR. Through setting the SNR, the analysis and simulation verification for detection sensitivity and confidence level can be made.Simulation verification shows that the monte carlo simulation result is consistent with the theoretical results, and the maximum deviation is only 5%, which is far less than the deviation caused by the space environmentdisturbance.
Explorer of fusion resolution test for fusion night vision system
Jiali Zhu, Xiaodong Liu, Chengbo Fei, et al.
Subjective and statistical methods were applied to evaluate the effect of fusion vision system which was lack of objective, convenient, engineering methods. Based on testing of resolution for night version system and MRTD for IR system, a evaluation method of fusion resolution was improved for fusion night vision system with the testing instrument of fusion resolution.
The illuminometer based on low-light-level image intensifier
Xulang Chen, Xiaofeng Bai , Qingyun Meng, et al.
With the view to the requirement of field experiments in Low-Light-Level (LLL) situation, the handheld digital illuminometer is designed based on LLL image intensifier, which is convenient to operate, smaller in size and weight. According to the linear relationship between screen-end current in image intensifier and illuminometer, the screen-end current is designed as signal input. It is converted from analog signals by A/D conversion, and displayed by display unit. Compare with the test data from standard illuminometer, modify MCU (Micro-programmed Control Unit) software. The illuminometer modified can measure the illumination range 10-3 lux to 10-2 lux, meet the demand of measuring in field experiments fundamentally.
Study on identification method of transfer function based on spatial frequency test
Xin Jia, Miao Yang , Yue Guo Sr.
The response property of spatial frequency applied on the transfer function test was studied. According to time-space conversion relationship of signals and multiplication coincidence detection technology, a high precision focusing assembled method is proposed. High accuracy and stability of the speed of light and electromagnetic signals during the transmission in space enable the camera performance parameters measurement of multiplication, which uses the temperature coincidence detection of signals transmission. The method proposes a new test scheme and described the key technology. Experimental results present that the model can overcome the limitation of traditional evaluating means. This method can satisfy the registration accuracy of 0.3 detector pixel sizes. It has practical value.
Hot carrier reliability of radiation hardened T-gate PD SOI NMOSFET after TID radiation
Jinghao Zhao, Jiangwei Cui, Qiwen Zheng, et al.
TID(total dose effect) and HCI(hot carrier injection) are hot issues of space application devices research in recent years. Previous studies drew the conclusion that TID radiation harden process can restrain HCI effectively. However, there have few reliability studies on radiation hardened device reported. In this article, the author irradiates RH T-Gate PD SOI NMOS and conduct a hot carrier experiment afterwards. He makes a detailed analysis of RH devices’ hot carrier reliability in different structure and reach a conclusion that radiation-induced HCI enhancement effect still exists in RH SOI experienced TID radiation because of the presence of buried oxide, which is contrary to results of previous studies on bulk silicon devices.
Off-axis digital holography system and paramecium identification method
Yexin Zhang, Baosheng Li, Xiaotao Yu, et al.
The digital holography technology is based on holography. A photodetector device is used instead of a holographic dry plate as a recording medium. The light intensity and phase information of the object is recorded, and the reproduced image is obtained by using a computer to realize the holographic reproduction process. Digital holography can perform noncontact, high-quality measurements and can obtain three-dimensional position information. This paper presents an off-axis digital holographic underwater microbiological detection method based on Jamin interferometer. For the identification of underwater microorganisms, the Euclidean distance identification method based on Hu invariant moments was used to identify underwater microorganisms. The experimental results show that the off-axis digital holography system constructed in this paper can clearly capture the underwater microorganisms, and effectively identify the paramecium and the feasibility of the verification system and algorithm.
New design of light field camera based on optic fiber plates
Jun-Cheng Qi, Bin Liu, Min Zhang, et al.
Light field image techniques attract more and more attention due to the ability of achieving digital refocus image and the measurement of depth of field and so on. But, before produce the light field sensor, the cover glass of the sensor would always be removed which result in oxidation and damage of the pixels of the camera. Based on the excellent optical performance of the optic fiber plates, a new design of light field camera was proposed to avoid the oxidation and damage of the pixels. First, remove the cover glass of the sensor, and then optical couple the optic fiber plates above the sensor and install the micro lens array on the optic fiber plates. After the experiment test, the results demonstrate that the established imaging system can provide multiple digital refocus images plane and may play an important role in the three dimensional imaging technology.
SWIR polarimetric system of spaceborne particulate observing scanning polarimeter
Hongchun Yang, Jin Hong, Maoxin Song, et al.
Particulate Observing Scanning Polarimeter (POSP) is a spaceborne spectropolarimetric sensor to map radiometric and polarimetric information of global atmospheric particulate matter. POSP has three SWIR bands, respectively are 1.38μm, 1.61μm and 2.25μm. So the SWIR polarimetric system is designed, which has the characteristic of division of aperture and division of amplitude to realize the simultaneous polarization measurement. The system has two identical optical paths, their orientation is 45 degree, and it can measure first three Stokes parameters. In order to realize to cool the InGaAs detectors below -60°C, combined with active cooler and passive cooler, the InGaAs detectors assembly and cooling system are integrated compact. The thermal vacuum test shows that cooling system could meet the cooling requirements of InGaAs detectors.
Focal plane fasten alignment and testing for the off-axis space borne mapping camera
Off-axis optical system can meet the needs of focus, FOV and optical distortion, the requirement of the optical system for space-borne off-axis mapping camera can be met well. In view of the strict requirements to the linear array horizontality and consistency of confocal plane for all FOV and all spectral, a method of computer aided adjustment model is proposed for quick alignment and test of the focal plane. Compare the traditional method, this method can both improve the efficiency and achieve high accuracy of alignment and test of the focal plane. The alignment and test result to a type long focal length mapping camera indicate that uniformity of the focal plane for all CCDs less than ±0.05mm and the linear array horizontality less than ±1 ′ .The result shows that this method is feasible and efficient. So it can provide a reference to fasten alignment and test of the focal plane for other space-borne off-axis mapping camera.
The improved method of interpolation computational ghost imaging in computational ghost imaging
Yujian Liu, Heng Yuan, Zhaohua Yang, et al.
Computational ghost imaging has great application prospect in the fields of national defense and biomedical because of its features of breaking the diffraction limit, being able to image under extremely weak background and harsh conditions. However, susceptible to the noise of the space environment, it has a low environmental signal-to-noise ratio. This paper propose an algorithm of interpolation computational ghost imaging(ICGI) in the field of computational ghost imaging. For the purpose of weakening the influence of dynamic interference in the ghost imaging, it insert specific patterns to a digital micromirror device in the original light-emphasis sequence, linearly estimate the change in noise by illuminating incoherent light, and correlate the optical signal of the object with the optical signal of the incoherent modulated light to calculate and reconstruct the image of the object. And This algorithm and the quality of image is improved by means of interpolating between different amounts of random patterns and inserting specific patterns of different complexity.
System design of dynamic visible scene projector based on digital-micromirror device
The visible light dynamic scene projector is a key component of the visible light imaging hardware-in-the-loop(HWIL) simulation test system.With the Digital Micro-mirror Device (DMD) as the key component, a dynamic visible light imaging simulation system was developed which will be used as the hardware in loop simulation platform for a certain type of airborne visible light imaging system.DMD fundamental operating principle and imaging theory are explained thoroughly. According to required,high-brightness RGB LED, aspheric condenser,light rod,relay lens,TIR lens were used to homogenize the illumination light. The optical projection system was specially designed to solve the large diameter and distance of exit pupil.The paper employed mature solution of DMD driving(TI) to achieve scene input,modulation and reproduce. The dynamic scene projector had been successfully applied to the HWIL simulation system of an airborne visible light imaging system, and had high real-time and fidelity, and met the requirements for use
Research on noise testing and reduction of low illumination imaging module
As the rapid development of back-illuminated CMOS (BI-CMOS) image sensor technology in recent years, its application prospect in the field of Low-Light-Level (LLL) night vision has been widely concerned. Therefore, LLL imaging module was developed based on BICMOS, whose 3-D noise data was obtained under different illumination conditions. The test results show that, the signal-to-noise ratio (SNR) of imaging module becomes worse with the decreasing of illumination. According to the judgement of noise, the noise power of the image in low illumination is mainly Gaussian distribution. And the image processed by spatial filtering, which efficiently reducing the imaging noise and improving the imaging quality.
Effect of refractive index measurement error on immersion grating spectral lines
Qian Tang, Chun Min Zhang, Bao Chang Zhao
Firstly, the effect of refractive index changes on spectral line spacing is calculated and analyzed. Because refractive index changes with wavelength-variety, theoretically, the 0.5 nm interval should be separated by 5 pixels. The spectral distribution will drift with considering the changes in refractive index. At the same time, the inversed spectral line drift caused by measurement errors(±1×10-3,±1×10-4,±1×10-5) are analyzed. The same refractive index error, the effect on long waves is greater than short waves. When the refractive index is positive, the spectral line drifts in the negative direction. When the refractive index is negative, the spectral lines drift in the positive direction, and the positive and negative drift are basically symmetrical. When the accuracy error of refractive index measurement is ±1×10-4, the spectral line drift is 0.7 pixels. When the error increases or decreases by an order of magnitude, the number of drift elements also increases or decreases by the same order of magnitude.
Image information from a dual channel optical synthetic aperture imaging system
Liwu Chen, Boacheng Zhao, Ren Chen, et al.
Introduce an optic system which by two fields of the system to observe the same object, it acquire two channels image of the object on the first imaging plate; and one by one the two channels image collimated by the array lens after them, then all the collimated beams were collected into the second image plate. As the two channels image were focus into the second image plate, super-resolution image of the object were acquired. The photos of the experiment proved this.
Hyperspectral Detection
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Egg quality traceability based on non-destructive testing technique of hyperspectral characteristics
Shiqi Huang, Xiangyang Duan, Wei Wu, et al.
The traceability of egg quality is related to the safety of the egg food, the traditional identification method is to use the egg quality parameters, and the operation process is too complicated. Hyperspectral characteristics reflect material properties, and each material has its own spectral characteristic curve, which is a very important feature for material classification and identification. In this paper, the spectral characteristic data of eggs was obtained by the spectrometers and the hyperspectral imaging instrument, respectively. After processing and analyzing, a nondestructive testing method of egg quality based on hyperspectral characteristics was proposed. The testing results are analyzed in depth, and some very useful conclusions are obtained.
Hyperspectral intrinsic image decomposition based on local sparseness
Zhiwei Ren, Lingda Wu
Due to the influence of conditions such as sensor status, imaging mechanism, climate and light, hyperspectral remote sensing images have serious distortion, which seriously affects the classification accuracy of hyperspectral remote sensing images. In this paper, the intrinsic image decomposition technology, which is widely used in computer vision and graphics, is introduced into hyperspectral image processing to perform intrinsic image decomposition on the original image. A hyperspectral intrinsic image decomposition method based on local sparseness is proposed. The automatic subspace partition and sparse representation theory are used to decompose the original hyperspectral image. The reflectance intrinsic image obtained by the decomposition is subjected to hyperspectral image classification processing. The experimental results show that the method proposed in this paper can obtain the intrinsic images better, and improve the classification accuracy of hyperspectral images to a large extent.
Athermalized polarimetric-spectral intensity modulation technology
Polarimetric-spectral intensity modulation (PSIM) technology can detect the polarimetric and spectral information of target simultaneously, which is quite useful in the realm of atmospheric detection, etc. The PSIM module consists of two multi-order waveplates and a polarizer. However, the multi-order waveplates are quite sensitive to the environmental temperature change, which could impact the detection precision of instruments severely. To solve this problem, the design strategy of athermalized PSIM technology is proposed. By gluing two different kinds of birefringent crystal, such as MgF2 and quartz, the PSIM module can be insensitive to the temperature change. The experiment result shows that, with the change of environment temperature, the imaging spectropolarimeter can detect the polarimetric information of target precisely. The error of detected degree of polarimetric information can be reduced to 0.01, which confirms the detection precision of polarimetric information.
Dictionary learning based target detection for hyperspectral image
Xiaorong Zhang, Bingliang Hu, Zhibin Pan, et al.
Target detection of hyperspectral image has always been a hot research topic, especially due to its important applications in military and civilian remote sensing. This paper employs the idea of classification and proposes a novel detection framework which incorporates dictionary learning and discriminative information. Due to the fact that target pixels lie in different subspace with background pixels, a novel detection model is proposed. In addition, a linear kernel is applied to project the image data into high-dimensional space, separating the target pixels and background pixels. Synthetic image and popular real hyperspectral image are used to evaluate our algorithm. Experimental results indicate that our proposed detector outperforms the traditional detection methods.
Comparison of hyperspectral retrieval models for soil moisture content
In order to improve the estimation accuracy of Soil Moisture Content (SMC) by hyperspectral technology, the paper used actual measured spectral data to study quantitative relationship between soil hyperspectral reflectance and the SMC. All total of soil samples from the Puzhehei Scenic Spot in Qiubei County, Yunnan Province in December 2016 were measured in the lab with the spectrometer. This paper used the original reflectivity of the soil samples and its four mathematical transformations as the inversion indicators to construct Unary Linear Regression Model (ULRM), Multiple Stepwise Regression Model (MSRM) and Partial Least Squares Regression Model (PLSRM) aiming to compare the performance and inversion accuracy of these three models, and find the best performance model to inverse the SMC. The results showed that: (1) It was determined that 1350nm, 1450nm, 1841nm, 1897nm, 1905nm, 1935nm and 2146nm were the hyper-spectral characteristic bands of SMC by analyzing the correlation between soil moisture content and reflectance. (2) The coefficients of determinations R2 varied between 0.73 and 0.91 and the Root Mean Square Error (RMSE) ranged from 1.51 to 1.86 with the best performance obtained with the PLSM, and the LRM had the lowest inversion accuracy. (3) The PLSRM established by the logarithm of the reflectivity of 1450nm, 1841nm, 1897nm, 1905nm, 1935nm and 2146nm was the best model of the 15 models by comparing the inversion precision of the samples in each model in this study
Study on extraction of foreign invasive species Mikania micrantha based on unmanned aerial vehicle (UAV) hyperspectral remote sensing
Jianhui Li, Dingquan Li, Gui Zhang, et al.
Mikania micrantha is a harmful foreign invasive species, which poses a great threat to the ecological balance and forestry production in southern China. In the study, typical Mikania micrantha multi-incidence area was used as the research area. After data pre-processing, 250 bands were obtained and subjected to a single factor ANOVA analysis. Anterior 10 bands with F values from the largest to the smallest were selected as the spectral characteristic bands. Spectral characteristics were extracted, together with texture characteristics. Texture characteristic of hyperspectral data was calculated by Gray level co-occurrence matrix, with processing window sizes of 11, 15, 21, 31, 41, 51, respectively. Results showed that the mean and second moment in processing window of 15 was more appropriate. A total of 200 verification points were randomly selected from five flight concentration areas. Visual interpretation was performed to verify the accuracy of the extraction. Results showed that the total accuracy was 85.5%. In this paper, key technology of unmanned aerial vehicle (UAV) hyperspectral remote sensing for extracting Mikania micrantha was studied, having constructed process of extracting the Mikania micrantha range by UAV hyperspectral data. Research results provide a new technical reference for the extraction of Mikania micrantha.
Lens mount for a refractive optics cooled by pulse tube cryocooler
Zhaoli Wang, Jingtao Liang, Miguang Zhao, et al.
Integration of optics inside a detector-dewar-cooled-assembly (DDCA) is a good strategy to miniaturized infrared cameras in order to provide small payload systems with thermal vision capability for both military and civilian applications. The optical additional mass has to be very small in order to limit the cool-down time of the DDCA. However, reducing the mass of these optical systems results in a decrease of the resolution and impaction on the image quality, making them difficult to use in the high-performance and high sensitivity applications. In order to achieve better optical performances, a classical optical system which consisted of four lenses was integrated in the DDCA. By optimizing the heat transfer of the lens mount and using a miniature pulse tube cryocooler(MPTC) as the cooling source, the cooling time of the system was reduced. The lens mount and the lenses were cooled down to 80K in an hour by the MPTC with 45W input power. The total mass to be cooled is 100 g, where the mass of the lenses is 15 g. In the later prototypes, the mass of the lens mount can be greatly reduced by optimizing the installation of the detector and the lens mount, and the cooling time of the cryogenic camera integrated with the high-performance optical system can be reduced to an acceptable range by using the lens mount heat transfer optimization method described in this paper.
Based on multi-scale hyperspectral near ground remote to sensing the quality of Southern Xinjiang jujube
Huaping Luo, Xueping Chai, Chong Chen
With multi-scales Hyperspectral Information processing, to explore the water quality change information of jujube large area outdoor. with near the ground remote sensing monitoring method. outdoor Zaoyuan hyperspectral image atmospheric correction, PCA, and other basic treatment methods, selection of jujubes spectra and characteristic wavelengths corresponding to labeled hyperspectral database. To mark and collect jujubes in the field of view of hyperspectral camera, By analyzing and correcting the spectral consistency of indoor and outdoor jujubes, the transfer between outdoor and indoor near infrared spectrum library was carried out. Combining the indoor quality measurement of southern jujubes and spectral correlation analysis method for extracting jujubes like spectral structure and quality feature information, the relationship changes between the different scales of spatial resolution and spectral resolution of the spectrum the conclusions, The scale of Single jujube and The scale of Canopy jujube tree indoor hyperspectral detection results are in good agreement, indicating that nearly ground to carry out indoor hyperspectral spectral consistency is good, through the spectrum image out door spectral database docking and model transfer. The establishment of the high spectral quality characteristics of jujubes perception model, exploring the growth process of jujubes outdoor large area change information of water quality with near ground remote sensing. provides an important reference in the future.
Relationship between land surface temperature and land use/land cover in Taiyuan, China
Ping Duan, Shuting Li
Four Landsat Thematic Mapper (TM) / Operational Land Imager (OLI) remote sensing images in 2000, 2004, 2011 and 2014 are used and a single-window algorithm is adopted to quantitatively retrieve land surface temperatures (LST) of Taiyuan City. A density slicing method is used to classify the city as an urban heat island. Land use types are classified in combination with a support vector machine. The relationships between LST and land use/land cover types, vegetation coverage and impermeable surfaces are analyzed, and those relationships between surface temperatures and impervious surfaces, vegetation, bare land and water bodies are studied quantitatively. The results show that the influence of the impervious surface on LST is much larger than that of vegetation, bare land and water bodies. The main factors affecting the surface temperature of Taiyuan City in the past 14 years are identified. Although the area of vegetation and bare land has either slightly increased or decreased, the increase in impervious surface area is the direct cause of the urban heat island effect of Taiyuan.
Chlorophyll-a concentration quantitative inversion and temporal and spatial variation in Zhelin Bay
Zhigen Liu, Lihua Xia, Fang Wang, et al.
Marine aquaculture has developed very rapidly in China and at present, China has become the largest producer of marine aquaculture in the world. While bringing huge economic benefits to China, aquaculture has caused serious damage to the coastal ecological environment, such as eutrophication of seawater and a series of water pollution problems. How to effectively monitor the pollution of offshore aquaculture to guide fishery production and prevent red tide is an urgent problem to be studied and solved. Remote sensing, with its advantages of wide coverage, periodicity and low cost, can effectively monitor the spatial and temporal changes of offshore polluted water bodies, which is conducive to the comprehensive analysis of Marine phenomena. In recent years, the eutrophication of waters of Zhelin Bay has intensified, which has become a red tide area, bringing serious economic losses to fishery. It is of great significance to study the distribution of chlorophyll a concentration and its spatiotemporal variation. Take the Zhelin Bay culture area in eastern Guangdong as an example, it is an important aquaculture base in China. Based on the measured hyperspectral data and the concentration of water quality parameters, the spectral characteristics of water body analyzed in Zhelin Bay .Remote sensing inversion model established by the optical classification theory. The accuracy of the inversion model verified by using multi-temporal Sentinel-2 satellite remote sensing images. The distribution characteristics and the temporal and spatial variation of Chlorophyll-a concentration were studied. The results show the reflectivity ratio at the wavelength of 705 nm has a good correlation with the chlorophyll a concentration, and the correlation coefficient is 0.7. For the sentinel-2 data, the model constructed with (Rrs(705)-Rrs(665))/(Rrs(705)+Rrs(665)) as the inversion factor has the best fitting effect, the determination coefficient R2 is 0.891, and the average relative error is 13.25%. Spatial distribution pattern of chlorophyll a concentration: chlorophyll a concentration is higher in the western and northern coastal aquaculture areas of Zhelin Bay, followed by the central net box culture area in the bay, and the shellfish culture area is lower. Spatial and temporal variation characteristics of chlorophyll a concentration: higher concentration of chlorophyll a found in the late stage of breeding, followed by the middle stage and the early stage. It provides scientific basis for the protection of offshore ecological environment, marine pollution monitoring and the coordinated development of fisheries.
Application and research of hyperspectral data in ground environment situation assessment
Wen Ma, Tong Zhang, Chunhong Dong
This study aims to establish a model for environmental situation assessment using hyperspectral data and apply it to regional and planning environmental assessments in the Northwest. The main research contents include: 1. The fusion of multi-level remote sensing technology. Hyperspectral data is a powerful complement to the ground environment monitoring data with its large scale and high precision. A multi-level remote sensing data processing mode integrating ground test, UAV remote sensing and satellite remote sensing is established. 2. The establishment of quantitative remote sensing analysis model. By determining the distribution range, location and extent of the relevant indicators of the target environment, combining the fixed field survey and the analysis of the on-site monitoring data, the eigenvalues are obtained, and the two are combined to establish a quantitative model for the identification of the fine environmental indicators of the environmental situation changes at large scales. 3. Application in the assessment of regional environmental situation in the Gobi region of the northwestern desert. Through the fusion analysis of ground test and high-resolution satellite remote sensing data, a quantitative model of regional desertification, plant disease and other environmental indicators is established. Combined with the analysis of hyperspectral remote sensing data in the planned area within two years, the progress and trend of environmental situation change can be known. This technology can be used to determine the impact of land desertification on planning and construction and the degree of risk.
Compact miniature snapshot imaging spectrometry using continuous variable filter
Tingkui Mu, Feng Han, Donghao Bao
Snapshot spectral imaging is a cutting-edge parallel acquisition technology for mapping the 3D datacube (2D spectral and 1D spatial information) of a scene in real time. Herein, we present a compact, miniature, snapshot Optically Replicating and Remapping Imaging Spectrometer (ORRIS). Its principle is based on the shifting of subimages replicated by a specially organized lenslet array and the filtering of each subimage by a continuous variable filter (CVF). The 3D datacube is recovered just using a simple image remapping process. The use of the lenslet array and the CVF makes the system very compact and miniature. A handheld proof-of-principle prototype is built in our laboratory by just using commercial-off-the-shelf products. It covers a wavelength region 360 nm to 860 nm with 80 spectral channels with a spatial resolution of 400 × 400 pixels. The volume of prototype is about 230 mm (length) × 70 mm (width) × 70 mm (height) and the weight is about 1.0 kg for finite imaging, and it will become 50 mm (length) × 70 mm (width) × 70 mm (height) and 0.5 kg for infinite imaging. The prototype is verified by measuring outdoor static and dynamic scenes.
Camouflage target detection based on short-wave infrared hyperspectral images
After years of development, military camouflage has formed a set of theoretical and technical systems represented by color camouflage. At present, a large number of camouflage technology research has been carried out for multispectral reconnaissance of visible and near-infrared. In order to better detect and identify the camouflage target, it is necessary to expand the new reconnaissance band and improve the spectral resolution of the reconnaissance instrument. In this paper, the research on camouflage target recognition technology is carried out through short-wave infrared hyperspectral imaging technology, and the camouflage target is identified by SAM, ACM and CEM algorithms respectively, and the characteristics of three methods in short-wave infrared camouflage target recognition are verified. This research can improve the ability to detect and identify camouflage targets and provide a new means for modern battlefield reconnaissance.
Review of retrieving soil heavy metal by laboratory-based hyper-spectroscopy
Laboratory-based hyper-spectroscopy is a technology based on the ground high resolution spectrometer under laboratory conditions. Owing to effectively controlling the interference level, it plays an important role in the research of soil heavy metal pollution concentration inversion. In this paper, the theoretical basis for the inversion of soil heavy metal content by spectral reflectance characteristics is discussed. The current study of laboratory-based hyper-spectroscopy on soil is analyzed. The common technical methods for the inversion of soil heavy metal concentration by spectral reflectance characteristics are summarized. The problems encountered in the application of laboratory-based hyper-spectroscopy are analyzed.
Research on the remote sensing prospecting model for typical uranium mining area along the Sino-Russian economic corridor
By leveraging the remote sensing technology, we have delved into the remote sensing prospecting model for typical uranium mining area along the Sino-Russian Economic Corridor. According to the remote sensing interpretation results of the basic geology along the Sino-Russian Economic Corridor, we have analyzed and summarized the remote sensing geological features of the structure, stratum and rock mass in this area. Moreover, by providing the remote sensing interpretation of basic geology in the Russian Streltsovsky typical hydrothermal uranium mining area based on the data of the domestic GF-1 satellite, we have made conclusive analysis on the characteristics of its ore-controlling elements and preliminarily summarized the remote sensing geological prospecting model for typical volcanic hydrothermal uranium deposits in this area. By using the remote sensing prospecting model, we have delineated three favorable ore-forming sections, which provides an important basis for regional mineralization prediction and the delineation of favorable ore-forming areas, and helps seek such deposits in the same or similar areas.
A high spectral remote sensing method for hyperspectral imaging
Spectral imaging technology is an optical technology that combines spatial optics imaging, spectroscopy and radiometry to produce images. The information cube data also contains the spatial information and fine spectral information of the ground scenery. Through the multi-information fusion detection method , we can effectively identify the disguised targets and false targets in the battlefield , therefor it is of great significance to the construction of national defense. However the spatial resolution of hyperspectral remote sensing remotely sensed by imaging mode is generally low, so it is difficult to meet the requirements of the modern war on the accuracy of military targets. Based on the above reasons, a high resolution hyperspectral imaging remote sensing method is proposed, which improves the spatial resolution to 2m, and effecteively solves the problem of detection complex targets in modern battlefield environment.
The extraction of altered mineral information based on WorldView-3 data
To promote uranium exploration in Chaganhada and provide remote sensing alteration anomaly information, this paper extracted chlorite alteration and iron-strained alteration by principal component analysis on the basis of analysis of wall rocks related to uranium mineralization and spectral characteristics of the typical alteration minerals in WorldView-3(shorthand for WV-3 in the following) bands. Then, the alteration information extracted was made processing on the ArcGIS platform, and an integrated anomalous information figure was compiled. The results of field verification show that the alteration anomaly information which extracted from WV-3 data is consistent with the reality. And the alteration anomaly information should be taken as one of the important clues in the uranium exploration in this area.
Atmospheric correction system for airborne thermal infrared imaging spectrometer: general design
Chengyu Liu, Honglan Shao, Feng Xie, et al.
As a new hyperspectral remote sensing technology, the thermal infrared hyperspectral remote sensing has the ability to observe the surface day and night. Instead of the surface temperature retrieval, the ultimate goal of the hyperspectral thermal infrared remote sensing data is to retrieve surface emissivity which can be used for mineral detection, ground parameters inversion and target identification and so on. Due to the inevitable atmospheric influence during the data acquisition process of thermal infrared hyperspectral imager, the atmospheric radiation information is included in the hyperspectral thermal infrared remote sensing data. The atmospheric correction with high precision is the premise of effectively implementing the subsequent applications. The aircraft, especially the unmanned aerial vehicle rising in recent years, is an important platform for remote sensing because of its flexibility, immunity to the cloud cover and high spatial resolution. The aircraft flies through the atmosphere when working, which makes the direct measurement possible for the atmosphere. On the basis of summarizing the features of the atmospheric correction methods for the hyperspectral thermal infrared remote sensing data, and the principle and process of atmospheric radiative transfer, the paper proposed an overall vision for the atmospheric correction based on the measured atmospheric downwelling radiance at the aircraft flight height, designed an atmospheric correction system for airborne thermal infrared imaging spectrometer, and stated the atmospheric correction procedure of hyperspectral thermal infrared remote sensing data using the system. The proposed system and procedure for atmospheric correction are able to acquire the atmospheric downwelling thermal infrared radiation information in real time, so without too many assumptions, it is possible to dramatically increase the precision of the atmospheric correction for the airborne hyperspectral thermal infrared remote sensing data and gives a promise to the objectivity of the data.
Study on the spectral reconstruction of typical surface types based on spectral library and principal component analysis
Weizhen Hou, Yilan Mao, Chi Xu, et al.
To meet the demanding of spectral reconstruction in the visible and near-infrared wavelength, the spectral reconstruction method for typical surface types is discussed based on the USGS/ASTER spectral library and principal component analysis (PCA). A new spectral reconstructed model is proposed by the information of several typical bands instead of all of the wavelength bands, and a linear combination spectral reconstruction model is also discussed. By selecting 4 typical spectral datasets including green vegetation, bare soil, rangeland and concrete in the spectral range of 400−900 nm, the PCA results show that 6 principal components could characterized the spectral dataset, and the relative reconstructed errors are smaller than 2%. If only 6−7 selected typical bands are employed to spectral reconstruction for all the surface reflectance in 400−900 nm, except that the reconstructed error of green vegetation is about 3.3%, the relative errors of other 3 datasets are all smaller than 1.6%. The correlation coefficients of those 4 datasets are all larger than 0.99, which can effectively satisfy the needs of spectral reconstruction. In addition, based on the spectral library and the linear combination model of 4 common used bands of satellite remote sensing such as 490, 555, 670 and 865 nm, the reconstructed errors are smaller than 8.5% in high reflectance region and smaller than 1.5% in low reflectance region respectively, which basically meet the needs of spectral reconstruction. This study can provide a reference value for the surface reflectance processing and spectral reconstruction in satellite remote sensing research.
Theoretical error analysis of photoelastic modulator based spectropolarimetric imager
Han Lin, Shuang Li
Photoelastic-modulator(PEM) generating a beat signal that modulates the polarized component of the incident light is employed in spectropolarimetric imager. Multispectral and polarized information can be achieved in target detection. The measurement accuracy is a critical technical index. In order to research the elements affecting the measurement accuracy of the instrument, the theoretical measurement principle and the optical structure characteristics are introduced. The polarization radiation measurement model is established by using mathematical description called Stokes-Muller and pseudo-inverse matrix is used to realize demodulation of incident light. Sensitivity of Degree of Linear Polarization (DOLP) retrieval to errors in retardance amplitude, retardance amplitude mismatch resulted from incident angle, scene gradient and phase error and detector noise is analyzed when different polarized incident light is considered. The result shows that relative error of DOLP is less than 0.5% and retardance amplitude error affects DOLP most. The study provides a theoretical basis for development, calibration and data processing of the instrument.
Study on hyperspectral detection and identification of invisible damage on kiwifruit by deep learning
Yan-xiang Wang, Zhang Yan, Cheng-ya Yang, et al.
Aiming at the problem that kiwifruit invisible damage is difficult to detect and identify by conventional detection methods, this paper proposes to use the visible near-infrared hyperspectral imaging technology to detect the identify and identify models based on deep learning VGG-16 neural network. Detection and recognition of hyperspectral images of kiwifruit invisible damage. The network is implemented by the caffe framework and python and is a 16-layer deep learning neural network. The reflection spectroscopy images of 50 kiwifruit samples were obtained at wavelengths of 400-1000 nm. According to whether they were subjected to invisible damage, they were classified into invisible damage and undamage, with 40 and 10 samples respectively. The training set and the test set are used to obtain the implicit damage discriminant model by using the principal component analysis image obtained from the spectral data as the input image of deep learning. The experimental results show that the highest accurate recognition rate reaches 100% and has a good recognition effect.
Design of a visible-near-infrared hyperspectral microscopy optical systems
ZhouFeng Zhang, BingLiang Hu, QingYe Yin, et al.
Hyperspectral imaging (HSI) acquires a three-dimensional dataset called hypercube, with two spatial dimensions and one spectral dimension. HSI is an emerging imaging modality for various medical applications, especially in disease diagnosis of early and biomedical research based on their unique spectral signatures. A visible-near-infrared HSI for microspectroscopy is designed, the measured spectrum is from 450 nm to 900 nm, which is sampled by 256 spectral channels. The spatial resolution is 1.25μm.The modulation transfer function (MTF) value of full spectrum and full field of view is close to the diffraction limit. At last, this microspecroscopy have been fabricated and preliminary tests have been implemented. The results indicated this visible-near-infrared hyperspectral microscopy optical systems have excellent optical performances. This hyperspectral microscopy will be well developed and used in the life sciences fields.
Design of a very high resolution FTIR atmospheric monitoring pre-amplifier circuit
Zhengyang Yu, Xin Li, Zhipeng Gong, et al.
Due to its high resolution, large flux, and high signal-to-noise ratio, Fourier Transform Infrared Spectroscopy (FTIR) is often used to monitor atmospheric environment. The preamplifier, as the key module of the FTIR optical receiver system, determines the accuracy, SNR and other key parameters of the subsequent signal directly. This paper presents a high gain and wide dynamic range preamplifier based on high performance integrated op amp. Using a low noise op amp IV conversion and multi-level Butterworth type active filter, a very weak signal input, multi-file Gain low noise and high SNR preamplifier circuit was designed. Experiments show: the preamplifier can make the signal of the atmospheric FTIR monitor meet the SNR and quality requirements.
Progress and prospectives on engineering application of hyperspectral remote sensing for geology and mineral resources
Remote sensing technology plays an important role in geological survey and plays an irreplaceable role. With the development of remote sensing technology, the appearance of hyperspectral remote sensing makes the application of remote sensing in geological and mineral fields have undergone a qualitative change. After nearly ten years of exploration and practice, the engineering application of hyperspectral remote sensing in geology and mineral resources has been preliminarily realized. With the launch of domestic hyperspectral satellites, it will further promote its application in geology and mineral resources. In this paper, the progress of engineering application of hyperspectral remote sensing in geology and mineral resources is summarized from the aspects of hyperspectral data processing, information extraction, information analysis, prospecting and prediction.
A design for a full-spectrum imaging circuit
Zhi-peng Gong, Yong-ping Li, Zheng-yang Yu, et al.
Two optical payloads on the GF-5 satellite have produced by Beijing Institute of Space Mechanics and Electricity. The full-spectrum spectral camera has the characteristics of wide spectral range, high spatial resolution and high accuracy of radiation calibration. It has reached the domestic leading and international advanced technology level, which has greatly improved China's high-precision observation capability. This paper designs a video circuit for the visible near-infrared spectrum of the camera. The circuit implements timing control and driving of the detector, as well as analog to digital conversion and processing of the analog signal. It completes the acquisition of 8 channels of analog signals, and outputs 14 bits of quantized bits and 30 Mbps of single channel data. The system achieves high signal-to-noise ratio (SNR) through high-stability power supply, high-speed drive level shifting and high-precision (2ns/step) timing control. Under the given simulation test conditions in the laboratory, the measured signal-to-noise ratio of the visible light channel reached 307, and good image data was obtained in the external scene imaging and in the space.
Improved N-FINDR based on object retrieval initialization for finding endmembers
Hao Wang, Chuntong Liu, Hongcai Li, et al.
In remote sensing images, the common existence of mixed pixels affects the classification of remote sensing images and the targets detection. The N-FINDR algorithm is a widely used endmember extraction algorithm. The algorithm is full- automatic. it has no parameters and has a good selection effect. However, in the volume calculation, the random selection of the initial value of the spectral endmember limits the efficiency of the method. The dimensionality reduction of the data loses some details; The automatic target retrieval algorithm uses the method of orthogonal subspace projection to determine the feature pixels. The algorithm runs faster and is more efficient, but it does not consider the angle between the pixels. Therefore, an improved N-FINDR algorithm based on object retrieval initialization is proposed in this paper. The improved algorithm can select the initial endmember, and then use the new volume calculation formula to solve the maximum volume of the simplex, so as to obtain the endmember, which makes up for the shortcomings of the two methods. Finally, simulation data and real airport diagram are used to verify the algorithm. The improved N-FINDR algorithm is superior to the traditional internal maximum volume algorithm in terms of running time and extraction accuracy.
Material classification technology based on convolutional neural networks
Dailin Li, Guilei Li, Baojun Wei, et al.
The contact measurement techniques are typically used in the field of object material classification. It has a lot of disadvantages, such as the complex operation and time-consuming. In this paper, a new non-contact object material identification method based on Convolutional neural networks (CNNs) and polarization imaging is proposed. Firstly, the relationship between the complex refractive index of object and the polarization information is simulated, and then the structure of the CNNs is constructed according to the specific conditions of the polarization imaging system. The accuracy of the identification method is measured by repeated test using 7 materials. The experimental results show that the CNNs model can quickly realize the object material classification with the polarization images, and the classification accuracy is above 92%.
Study on the growth and spectral response of rice with different nitrogen morphologies in water-saving irrigation model
Zhifang Xiao, Xilin Fang, Yue Wang, et al.
Hyper-spectral remote sensing is now a frontier of the remote sensing technology, which can monitoring chlorophyll content rapidly and nondestructive. In this study, four nitrogen forms were set up:ammonium sulfate (ammonium nitrogen) B1, potassium nitrate (nitrate nitrogen) B2, urea (amide nitrogen) B3, and formaldehyde urea (slow effect nitrogen fertilizer) B4. The chlorophyll content of B4 treated with different nitrogen forms was significantly different. Spectral parameters also show good correlation. The chlorophyll content estimation model constructed with the spectral parameters DVI(755,690) and DVI(810,690) has a good fitting degree, and the linear model R2 has reached a significant level, respectively. Rice treated with traditional urea had a lower growth rate than the other three types of nitrogen, the slow effect nitrogen fertilizer and ammonium nitrogen were suggested to improve nitrogen utilization efficiency and eventually reach the goal of high yield.
The impact of drift angle control and LTAN drift towards hyperspectral solar occultation and calibration
The solar occultation observation or solar calibration of the payload requires the sunlight or the diffuse reflection of sunlight to enter the field of view. It’s important to consider the variation of azimuth and elevation angle from the. The article analyzes the impact of in-orbit drift angle control and LTAN drift of 8 years in-orbit towards the solar vector. On the basis on the occultation period and solar calibration period, the range of the solar driven angle, the solar observation FOV, timing of the calibration and the optimal LTAN range are analyzed. The analysis method can provide reference for similar payload design and orbital control design with solar observation requirements.
Development of unmanned airborne array filter spectroscopic multispectral camera
With the development of miniaturization of drones and spectral cameras, unmanned Airborne spectral imaging technology has become possible. How to reduce the volume and quality of multi-spectral cameras while improving data acquisition performance and efficiency, making them more widely used in low-altitude remote sensing has become the focus of current research. In this paper, we develop multi-spectral camera development and data preprocessing technology based on array filter splitting. In the development of camera, we replace the optical path splitting, filter wheel and multi-lens splitting by filter splitting, which solves the multi-spectral camera. At the same time of data quality, two array filters were designed because the imaging method limited the camera to the ideal volume and quality. The improved filter greatly reduced the spectral aliasing between the bands. In the data processing, an improved SURF stitching algorithm based on sparse matrix beam adjustment is proposed to improve the speed of image stitching. The research results show that this paper successfully developed a multi-spectral camera with simple optical path, high acquisition efficiency, stable performance, small mass and low cost, and successfully combined with small and small drones for data acquisition and processing. The academic value and production value, the data acquisition achieves the generation of multi-spectral image of the whole scene, and the band stitching precision is 0.12 pixels, which has high application value.
Acquisition method and calibration application on hyperion hyperspectral reflectance
Chunyan Zhao, Wei Wei, Meng Zhang, et al.
As the most commonly used hyperspectral data source, the acquisition method of Hyperion hyperspectral reflectance became more and more important. In this study, a batch atmospheric correction method based on Second Simulation of a Satellite Signal in the Solar Spectrum radiative transfer code (6SBAC) has been presented. The 6SBAC was used MODIS synchronous atmospheric data products to obtain meteorological parameters, and set up automatic input-output parameter module to obtain Hyperion reflectance data. At the same time, using Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH), Quick Atmospheric Correction(QUAC) atmospheric correction methods on Hyperion satellite images, the results was compared with the synchronous hyperspectral data measured in Dunhuang test site. The authenticity of the obtained hyperspectral reflectance was verified by MODIS surface products. The results showed that the hyperspectral reflectance obtained by the three kinds of atmospheric correction methods were consistent with the measured reflectance in trend. Despite the compromises in different wavelength regions 6SBAC is found to be a better corrector method for the Hyperion hyperspectral reflectance acquisition. The precision of the 6SBAC obtained hyperspectral reflectance can meet the application requirements and improve the acquisition efficiency of Hyperion hyperspectral reflectance data.
Research of wide swath image mosaic technology based on area-array detector adopting whiskbroom scanning mode
Sai Li, Yin Qiu, Yong Hu, et al.
A new method of splicing infrared thermal Unmanned aerial vehicle(UAV) image with special acquisition mode is presented. We used the bi-directional whiskbroom scanning frame infrared UAV (300,000 pixels) developed by the Shanghai Institute of Technical Physics,Chinese Academy of Sciences(SITP) to obtain the image of an area in haiyan,Zhejiang province.In order to get more accurate temperature data in a wide range, correction and optimization of the mosaic strategy of this infrared image are needed.In this paper, an orthographical correction model based on drone position and orientation system (POS) parameters was established, By optimizing scale invariant feature transform (SIFT) matching parameters and Random Sampling Consensus (RANSAC) algorithm, more reliable matching results were obtained.After rough calculation of adjacent images by image location to calculate whether it is an adjacent image, this can reduce the operation time of the splicing algorithm.The overlapping area images fused with the multi-resolution pyramid algorithm. Finally, the large area image and temperature inversion map of the study area were obtained. Inversion results showed that the error of temperature inversion less than 0.2 degree by comparing with the original temperature before unspliced.It can meet the subsequent application requirements of the UAV infrared image.
Multispectral evaluation method of low characteristic signal propellant
Ying Sui, Chen-guang Zhu, Jun Zhao, et al.
It is a difficult problem to evaluate the signal parameters of optical radiation characteristics of solid propellant. The research proposes a multispectral evaluation method of propellants radiation signature index (PRSI). The infrared radiation intensity, ultraviolet radiation intensity and visible radiation intensity of both HTPB composite propellant and nitrocellulose propellant were tested with infrared radiometer and ultraviolet and visible light radiation measuring instrument, and then used the method of PRSI to compare the test results. The results show that the PRSI values of UV and visible light produced by the combustion of HTPB composite propellants are significantly larger than those of the nitrocellulose propellants. The multispectral exponential factor evaluation method based on the inherent parameters of propellants, such as mass-combustion heat and burning velocity, can not only compare the difference of spectral characteristics of similar propellants, but also compare different types of propellants.
Temperature sensitivity of the focal plane of thermal infrared splitting window band
It is widely used to correct the atmospheric and surface emissivity by using the split window algorithm to eliminate the atmospheric influence through the combination of the measured values of two adjacent channels (10.3-12.5 m) In the thermal infrared remote sensing inversion of surface temperature. With the increasing demand for split-window spectral data, the development of space optical remote sensors with these two spectral bands has gradually increased in recent years. High-resolution 5 full-spectrum spectral imager is a typical example. Its spatial resolution of thermal infrared split-window spectral band reaches 40m, which is an international advanced level. A large number of studies have shown that the thermal infrared splitting window is very sensitive to the focal plane temperature. With the change of the focal plane temperature, the imager output digital signal varies greatly. For example, when the focal plane temperature changes 0.1K, the 10.3-11.4m spectral band changes 0.02V (equivalent to 13.6DN), 11.5-12.5m spectral band changes 0.006V (equivalent to 4.08DN), so the temperature of FPA must be corrected or controlled strictly.
The on-orbit calibration method of hyper-spectral fluorescence imaging spectrometer
Yilan Mao, Tao He, Fang Ren, et al.
Chlorophyll fluorescence intensity is affected by the photosynthetic efficiency and the physiological status of plants under various environmental conditions. Chlorophyll fluorescence signals also beneficial to estimate vegetation productivity and vegetation carbon cycling. The use of spaceborne hyperspectral imaging to observe the chlorophyll fluorescence, can greatly increase the observation efficiency, which is conducive to global coverage of fluorescent data. According to the characteristics of space-based remote sensing, the inversion accuracy of chlorophyll fluorescence data depends on the radiation and spectral accuracy of the observing system, which requires high precision ground calibration and on-orbit calibration. Based on the observation elements and the satellite orbit, the on-orbit calibration scheme are proposed, including the field of view, instrument measurement, uncertainty analysis and correction.
Study on the depolarization grating
The depolarization grating is needed particularly for use in imaging spectrometers used in sensing the atmosphere weak CO2 spectral band (1595nm - 1625 nm) at spectral resolution in the order of 0.1 nm whilst ensuring a high efficiency for both TE and TM polarizations. The diffraction characteristics of the depolarization grating have been investigated by using rigorous coupled wave theory. The simulation results show: the groove depth and duty cycle of the depolarization grating must be controlled within the range of 730nm-780nm and 0.3-0.37 respectively, in order to guarantee the 1 order diffraction efficiency is over 70% for both TE and TM polarizations at the atmosphere weak CO2 spectral band. The depolarization grating with the period of 869nm in a fused-silica substrate of 120 mm × 97mm will be fabricated by holographic lithography - ion beam etching in late 2018.
Laser Detection
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Kilowatt-level, high brightness, narrow-linewidth PM fiber amplifiers based on laser gain competition
Daren Meng, Pengfei Ma, Xiaolin Wang, et al.
Stimulated Brillouin scattering (SBS) management in kilowatt level, high brightness, narrow spectral width, and all polarization-maintained amplifiers by using laser gain competition is demonstrated. This method can increase the SBS threshold of the fiber amplifier by more than twice without changing the linewidth. By further incorporating phase modulation technique, the SBS threshold is scaled to be as high as 32.4 times compared with single frequency amplification. Output power of 1082 W is achieved with polarization extinction ratio (PER) of ~ 14 dB, linewidth of <7.6 GHz and beam quality (M2 factor) of ~M2 =1.14 in a preliminary validation experiment. This kind of fiber source has great potential in the applications of high power coherent beam combining (CBC) or spectral beam combining (SBC) systems.
Morphology study of ZnTe crystals grown from Te-rich solution
Scanning electron microscope (SEM) was used as a powerful tool to analyze the morphology of ZnTe crystals grown from Te solution. ZnTe crystals found on the end of ZnTe ingot are with micron- to submilimeter size, and their shapes can generally be classified into polyhedral type with smooth facets, and skeletal type with concave faces. The morphology formation mechanisms were discussed. It was found, the ZnTe crystal shape and surface morphology is very sensitive to the growth condition. In spite of the thermodynamics factor (Gibbs free energy theory), the kinetic factors, such as the crystal size and crystalline driving force, play more essential roles in the control of the shape of ZnTe crystals.
4.115 kW near diffraction-limited high quality fiber laser based on 25/400μm fiber
Luo Yun, Dong-yang Zou, Cheng-yu Li, et al.
A direct diode-pumped all-fiber-integrated fiber laser based on backward pumping master oscillator power amplifier configuration at 1080 nm, producing maximum output power of 4.115 kW based on 25/400 μm fiber with corresponding linear fitting optical to optical efficiency of 78.39% was demonstrated. The suppression ratio of stimulated Raman scattering is better than 35dB and it can be further optimized by decreasing the seed input power. Near diffractionlimited beam quality (M2 are 1.7and 1.6 in the x and y directions based on 4-sigma method) is also achieved at the maximum output power. To the best of our knowledge, this is the first report for 4 kW near-diffraction-limited fiber lasers based on 25/400 μm fiber directly pumped by laser diodes.
Influence of space environments on the laser damage of space laser system
Laser technology and laser system has more and more important implication in spacecraft engineering. But different from ground environments, space environments include vacuum, extreme temperature and thermal cycling, space radiation environment such as electron, proton, heavy ions, ultraviolet, contamination, and so on. Space environments may have damage or threaten to the space laser system, especially to their optical devices. So the influence of space environments on the laser damage of space laser system should be studied. In this paper, space environments of space laser system encountered is introduced firstly, and then the influence of space environment on space laser system is discussed. Thirdly, the damage mechanism of space environment on laser damage is analyzed. At last, some works or countermeasures were proposed to improve the laser radiation damage threshold of laser system in space environments.
The influence of core filling of the gradient multimode fiber
The process of preparing fluorine-doped multimode gradient optical fiber preform by MCVD is studied in this paper. Different core reactants are doped to form different core refractive index distributions. It is found that the core with more germanic chloride and phosphorus has better refractive index distribution. But it is not conducive to the radiation resistance of the fiber.
Birefringence of PM laser fibers with different structure
Polarization maintenance fiber with high birefringence is an important goal for the development of high power fiber lasers. There are different ways to achieve high birefringence, such as change shape of a fiber’s core and apply stress to a fiber’s core. In this paper, fibers with different ovality of elliptical core are fabricated and tested. On the other hand, stress type PM fibers are also made, including PANDA type fibers and bowtie type fibers. Their test results are compared and analyzed together with their structures. Generally, the bowtie type fibers has highest birefringence, while the PANDA fibers are with high birefringence and high production efficiency. Different application can choose different type of PM Laser fibers.
Synergistic effect of laser radiation and space natural radiation environments on spacecraft
Zicai Shen, Wei Dai, Yigang Ding
Spacecraft will be damaged by space radiation environments such as electron, proton, X-ray, gamma ray, ultraviolet, and so on. For laser system used in spacecraft, its laser materials and laser devices will be damaged by laser beam. Besides, surface materials of spacecraft can be damaged by high energy laser too. So, spacecraft materials and devices may be damaged by synergistic effect of laser radiation and space natural radiation. In this paper, space radiation environments are introduced firstly, and then synergistic mechanism between laser and space radiation environments are discussed. Thirdly, test method for synergistic effect of laser radiation and space natural radiation on spacecraft is analyzed. At last, some directions are suggested to improve the space environment adaptability of spacecraft in space radiation environments and space laser radiation environment.
Design and realization of target tracking module of UAV laser charging system
Jia-ju Ying, Dong-sheng Wu, Jie Liu, et al.
Judging from the information war in recent years, the future battlefield UAV will play a huge role. The length of the endurance has become one of the main factors limiting its performance. Using laser beam to charge the flying UAV in real time is a powerful means to greatly extend its endurance and improve its operational efficiency. Accurate target tracking of the charging panels on the aerial flying UAV is a key technology for the subsequent laser beam charging. Aimed at the target tracking module of UAV laser charging system, hardware and software are designed respectively. The structure of each part of the hardware system and the related parameters are analyzed. The software design process and key algorithms are described. In this paper, the target tracking aiming test is carried out by combining the charging panel of the UAV, and various error factors in the process of target tracking aiming are analyzed.
Fabrication of Yb/Ce-codoped aluminosilicate pedestal laser fiber
We fabricated and reported a pedestal fiber with Yb/Ce-codoped aluminosilicate (Al2O3-SiO2) core and germanosilicate (GeO2-SiO2) pedestal. This newly-optimized chelate precursor doping technique enables us to make homogeneous large-core pedestal fiber with strong pump absorption from Yb3+ ions about 3.66dB/m at 915nm. The fiber core was homogeneously doped with 4450ppm Yb3+, 11600ppm Al3+ and 1800ppm Ce3+, and surrounded by pedestal layers with 25000ppm Ge4+. The results indicate all-gas-phase chelate precursor doping technique is highly competitive for the fabrication of pedestal fiber towards narrow-linewidth fiber laser.
Research on compatible green stealth photonic thin film against near infrared and 1.54μm laser
A compatible green stealth photonic thin films against near infrared and 1. 54μm laser, based on the structure of photonic thin films are designed to achieve compatible stealth of targets in background of green plants. Optical thin films have the advantage of regulating characteristics of the beam transmission. In this paper, the thin films are designed to simulate NIR Plateau of the spectral characteristics of green plants in the range of 0.78μm to 1.3μm and form a reflection Valley at 1.54μm. Based on the transfer matrix method (TMM) of thin-films optical theory , the Needle Algorithm and Tunneling Algorithm of thin-film automatic design methods are combined to optimize and design the green thin films. Finally, the near infrared green optical thin films with NIR spectral characteristics similar to the green plants are designed. And the spectral curve has a reflection valley near the center wavelength of 1.54μm ,and the reflectivity of the wavelength of 1.54μm is as low as 5%,achieving the stealth of the laser detector with the wavelength of 1.54 μm. On this basis, the influence of four incident angle of 0°,10°,20°and 30° on the spectral curve is analyzed. The results show that the spectral curves still meet the design requirements.
Analysis on key technologies of laser defense against high speed moving stealth target
Jie Fu, Baolin Du, Dezhao Zhou, et al.
In modern war, high-speed moving targets such as fighter planes are the key point to reverse the situation of war. Such targets not only move fast, but also stealth performance is getting better and better. By studying the characteristics of high speed moving stealth target, the key technologies of laser defense against high speed moving stealth target are analyzed from the aspects of quantum imaging and quantum detection, and the problems that need to be studied in each technology are pointed out.
Vortex beam amplification based on chemical oxygen iodine amplifiers
Chemical oxygen iodine laser, or COIL, is an impressive type of chemical laser and is widely adopted in the past several decades. A novel approach for obtaining high power vortex beam is explored. A seed vortex beam is amplified by a chemical oxygen iodine amplifier. Numerical simulation is carried out to confirm the feasibility of obtaining high power vortex beam based on chemical oxygen iodine amplifiers. The behavior of the vortex beam is also revealed. As the beam is modulated by the gain media, the beam profile gets asymmetric, and the vortex center no longer locates at the midpoint between the upstream and downstream intensity maximum points. This study suggests a potential approach for developing chemical oxygen iodine lasers.
Simulation study for the influence of laser-emitting system on beam quality
Lai Jiang, Jie Zhou, Jingqi Yang, et al.
The laser-emitting system is an important part for the laser system. The system can be used to expand, transmit beam and focus it on the target. While due to the aberration, the beam quality passing the emission system can be changed, which affects the power density on the target and the damage effect. In order to effectively evaluate the damage capability of the transmitted laser to the target and the performance of the emission system, assist the system design, an engineering method for the beam quality calculation of the emission system is proposed.
A high power Q-switched Ho YAG laser pumped by two Tm-fiber lasers
Fang Chen, Meng Cai, Yuansheng Zhang, et al.
High efficient and high power 2μm room temperature Ho:YAG laser by two Tm-fiber lasers at 1.91μm was demonstrated. A maximum continuous wave output power of 55.6W was generated, corresponding to the slope efficiency of 61.3% with respect to the incident pump power. At 18kHz of the pulsed repetition frequency, we achieved a less than 31ns FWHM pulse, with the maximum output energy per pulse of 3.0mJ. A beam quality of M 2 <2.4 was achieved.
Dynamic modeling and parameter updating of φ150mm mirror
Ding Cui, Zhaoxiang Deng, Changchun Ye, et al.
In order to improve the accuracy of the dynamic model of the mirror, the joint modeling method of the mirror is studied, and the equivalent model of the structure is proposed. Aiming at the problem that too many model parameters are difficult to be determined by theoretical method, a model updating method is established with the experimental data as the objective. The correction results show that the accuracy of the numerical model is greatly improved, which provides a reference for the high confidence modeling of the optical-mechanical structures.
Effects of F- on the optical properties of Yb3+-doped large mode area silica fiber prepared by sol-gel method
Yb-Al co-doped rod glass introducing with F- as the large core of photonic crystal fiber (PCF) was prepared by solgel method combined with high temperature sintering, and the rod without F- was fabricated as the comparison. The refractive index and homogeneity of the rods, and the attenuation, laser properties of the fibers have been investigated to confirm the effects of F- in the fibers. The results show that introducing F- in the fiber core can obviously decrease the refractive index of Yb3+ doped silica glass, and the beam quality of the PCF has been greatly improved by the lower NA of core.
Numerical study of effects of incoming flow inhomogeneity on the flow characteristic at the gain region of COIL
Based on the computing fluid dynamics, the effects of the inhomogeneity of the flow filed at the nozzle entry on the flow characteristic at the gain region were investigated. The computing results indicate that the asymmetric -inhomogeneous conditions can induce the asymmetric influences and the boundary layer separation at the gain region. The symmetric - inhomogeneous conditions with different profiles have different effects. Along the nozzle spanwise direction, the incoming flow with the regular triangle pressure profile can increase the shock wave intensity. The flow structure is broken and the interaction position of boundary layer and shock waves move upstream in the condition with the regular triangle pressure profile. All results can provide information for study and design of the pipe at the COIL nozzle upstream.
266nm pulsed laser damage on UV image intensifier
Yuntao Xie, Xi Wang, Xiaoquan Sun, et al.
The damage of a nanosecond pulse laser on ultraviolet(UV) image intensifier was studied. A laser pulsed with a wavelength of 266nm and pulse width of 25ns was used to radiate an UV imager intensifier. The laser induced damage threshold(LIDT) of the internal components of the UV imager intensifier was measured, and the LIDTs of the optical windows, the microchannel plate and the ultraviolet photocathodes are 1.8mJ / cm2 , 3.3mJ / cm2 and 17.6 mJ / cm2, respectively. It is shown that as the incident laser energy increases, the order of damage of the components inside the image intensifier is: photocathode, microchannel plate and optical window.
Realization of Lambertian laser source based on light scattering in solution
Qiushi Wang, Caixia Wu, Yizhuo Zhang, et al.
Laser decoy is widely used in the field of electro-optical countermeasures, against laser guided semi-automatic weapons. Decoy laser usually includes a laser light source with specific wavelength and signal, whose energy distribution has Lambertian reflection characteristics. With a 633nm laser source, a fibre and a diffusive module, a homogeneous field laser was illustrated, which was generated through high-density colloidal dispersion to get diffused. By optimizing the fibre and structure parameters, the laser light energy utilization was improved while maintain light field uniformity. Additionally, the flat field system was designed and tested using high reflectivity PTFE material, with a reflectivity of 97%. A developed Lambertian light source system for reference-based Laser decoy was established, whose non-uniformity was lower than 0.3%. The results showed that the Lambertian light source system could meet the requirement of Laser decoy, and needed to be improved in near infrared.
Stable Yb-doped all-fiber nanosecond pulse laser based on electrochemical delamination black phosphorus
Jian Wu, Tao Wang, Xiaoxi Jin, et al.
A black phosphorus saturable absorber (BP-SA) fabricated by a modified electrochemical delamination strategy exfoliation process was inserted inside a Yb-doped ring laser cavity. Based on this BP-SA, a stable nanosecond pulse laser could be achieved. When the pump power increased to 151 mW, a fundamental repetition rate of 6.78 MHz and 3.38 ns pulse began to initiate. The pulse could initiate stably at least 3 hours each day for a week. These demonstrations indicate that the related thin-film BP SA preparation method would make the construction of pulse laser more efficient and benefit industrial community in the future.
DF chemical laser's diluent gas influence on output power and absorption on zeolite
Fu Yang, Zhijie Wang, Zhipeng Zhou, et al.
Diluent gas is one of the HF/DF chemical laser fuel gas compositions, which adjust and control combustion temperature. Different diluents affect laser output power. In this paper, firstly we investigated the power variety of chemical DF laser connected to vacuum tank which took He, Ne, Ar, N2 as diluents respectively. Then we studied the absorbility of the four diluents on zeolite. The results showed that the output power of diluent gas was He>Ne>N2>Ar; the adsorbance was <<HeNe<Ar<N2. So we concluded that the N2 was the best diluent gas candidate for DF chemical laser with a cryosorption vacuum pump to adsorb the exhausted gas.
The ZnGeP2 OPO pumped by the Ho:YAG laser
Fang Chen, Yuansheng Zhang, Meng Cai, et al.
We report a Ho:YAG laser as a pumping source of the ZnGeP2 optical parametric oscillator (OPO) efficient. The Ho:YAG laser end pumped by a Tm fiber laser. We achieve the maximum average output power of 9.48 W with a linear cavity of OPO laser by the maximum output power of 23.5 W with a single-pass pumping of the Ho laser. The OPO laser provide a number of distinct benefits for integration into next generation DIRCM systems.
Mirco-nano Detection
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Arbitrary-bent-waveguide optical diodes based on surface magnon polariton
Changyi Wu, Zhiliang Chen, Junxing Fan
Through numerical experiments by finite-element method, we have demonstrated arbitrary-bent-waveguide optical diodes utilizing surface magnon polaritons (SMP) waves on the surface of ferrimagnetic materials. Ferrimagnetic bulk-material slab waveguides and their propagation characteristics of SMP waves are presented. Such surface-wave based waveguides, which could be bent in arbitrary degrees, are shown to be promising elements for one-way transmission as optical diodes. The obtained results show that the optical diodes can have huge isolation coefficient and low insertion loss without requiring nonlinear material and polarization elements. Furthermore, the direction of the optical diode can be controlled by an external magnetic field.
1.3 μm laterally-coupled distributed feedback laser with a triangular prism etched facet
Q. C. Wang, J. Wang, Y. Q. Wang, et al.
The distributed feedback (DFB) laser is a key component for fiber communication due to its single-mode performance, but it usually requires complex and expensive regrowth after grating definition. The laterally-coupled distributed feedback (LC-DFB) laser has the advantage of a simple fabrication process without epitaxial regrowth, but the LC-DFB laser usually has a low coupling coefficient as the optical feedback is provided by the evanescent field and Fabry-Parot (FP) longitudinal modes arise from the pair of parallel cleaved facets. In this work, a triangular prism etched facet is proposed to suppress the FP longitudinal modes from cleaved facets of a 1.3 μm LC-DFB laser. The length-width ratio of a triangular prism facet is optimized on the compromise between the reflection and length by finite difference time domain (FDTD) method. The vertical etched facet with depth of 4 μm and tip curvature of 100 nm and the lateral gratings with depth of 1.8 μm and gap of 200 nm are fabricated by inductively coupled plasma (ICP) etching with the gas mixtures of Cl2/CH4/Ar and CH4/H2/Ar, respectively. The FP longitudinal modes of the etched-facet laterally-coupled distributed feedback (EF-LC-DFB) laser are effectively suppressed compared to the counterpart of cleaved facets, and the stable single-mode operation of EF-LC-DFB is demonstrated with the side mode suppression ratio (SMSR) of 54.35 dB.
Deep tissue focusing based on machine learning
Ke Si, Yiye Zhang, Yuncheng Jin, et al.
Non-invasive deep tissue imaging and focusing is highly demanded in biomedical research. However, for in vivo applications, the major challenge is the limited imaging depth, a of random scattering in biological tissue causing exponential attenuation of the ballistic component the light wave. Here we present the optical focusing with diffraction-limited resolution deep inside highly scattering media by using machine learning. Compared with conventional adaptive optics, method can not only provide high-speed sensor-less wavefront measurement with more than 90% accuracy, but also dramatically reduce photobleaching and photodamage. This technology paves the way for many important applications in fundamental biology research, especially in neuroscience.
Theoretical analysis of multiple plasmon-induced absorption effects in plasmonic waveguides side-coupled with resonators structure and its applications
Single and double plasmon induced absorption (PIA) effects have been numerically achieved in a metal-insulator-metal (MIM) waveguides end-coupled with resonators structure. Here, the structure composed of two MIM waveguides and three side-coupled rectangular resonators is proposed to generate double PIA effects. A multimode coupling mechanism derived from the coupled mode theory is established to describe the spectral features, which is greatly agree with the simulation results, may provide a guideline for designing and analyzing the integrated plasmonic devices based on the multiple PIA effects. What’s more, dynamical control of the amplitude and bandwidth of the multiple PIA effects can be achieved by means of filling poly (methy1 methacrylate) or Kerr material in the Fabry-Perot resonators. Compared with previous reports, the multiple PIA effects are analyzed theoretically in a plasmonic waveguides end-coupled with resonators structure, will have practical applications in plasmonic filters, modulators, sensors, switches and fast light in highly integrated plasmonic circuits.
A novel polysilicon light source and its on-chip optical interconnection structure design
Hongliang Sun, Kaikai Xu, Jianming Zhao, et al.
The rapid advancement of microelectronics technology places higher demands on the interconnection of integrated circuits. The continuous reduction of the critical dimension in the microelectronics fabrication process has led to an increase in the power consumption of the metal interconnect lines. There are many advantages of the on-chip optical interconnect structure, like high speed or low power consumption. Therefore it is one of the best alternatives to the metal interconnect process. GaAlAs/ GaAs is used to make light sources of common optical interconnect structures and these light sources are poorly compatible with CMOS processes. In this paper, we designs a new structure of silicon-based avalanche light source (SBALS), which has the advantages of being compatible with CMOS technology, based on the existing theory of SBALS. And we preliminarily design an on-chip optical interconnect structure by SBALS, which is proposed for optical interconnects in integrated circuits.
High-precision high-speed and noninvasive optic distance measurement
Daowei Pan, Junxiang Wang, Ning Tang, et al.
In all kinds of optical applications, the precision of central optical distance has significant influence on the desired imaging properties according to the optical design requirements. In this paper, we present a measurement method for the determination of the central distance both in assembled systems and single-lens with high precision, high speed and non-invasive characters. The distance between optical surfaces are optically measured by the mean of swept source domain interferometric system. A fiber-optics system with a central wavelength 1310 nm is built, the central distances of all surfaces within coherence length can be quickly measured at the same time. The system pixel resolution is about 0.1μm calibrated by Mitutoyo standard level-zero gauge and calculated by Fast Fourier Transform (FFT) and zero-padding algorithm. System precision double checked by other gauges is less than 0.3μm. The standard gauge-sets and a lens were measured by this system, the result also verified the high precision. The systematic error is less than 0.3μm and the sensitivity is about 22μm experimentally. The high speed swept light source (100kHz used in system) ensures the quick measuring speed. This measurement method has high precision, high speed, non-invasive and high sensitivity characters, and can be applied in related optical system.
Periodic bulk motion correction method in decorrelation-based optical coherence tomography angiography
Jinyu Fan, Jingxuan Liu, Quan Wang, et al.
Decorrelation-based OCTA is a widely used optical coherence tomography angiography method which utilizes OCT intensity information. However, cardiac and respiratory motions in animals are seriously degrade image quality. These kind of bulk motion is periodic, and its C-Scan (slow scan) direction component hinder motion correction because of scan position and OCT structure’s change. Some correction methods were proposed, but vasculature information will be lost when larger bulk motion occur. Here we demonstrate a correction method which uses stitch scan protocol in C-Scan direction, and sets a threshold to the maximum value of normalized cross-correlation among repeated B-Scan intensity signal to exclude false OCT B-scans. Result of In vivo imaging experiment for mice indicates that our method can reserve whole vasculature information and effectively improve image quality.
Fabrication of the drift-enhanced InGaAs p-i-n photodetectors
G. Y. Li, B. Niu, X. W. Gu, et al.
We have demonstrated a class of drift-enhanced InGaAs/InP p-i-n photodetectors with the top-illuminated light in the 1550 nm wavelength band. An InGaAsP layer is used at the InGaAs/InP hetero-interface to reduce the contact resistivity. For devices of 10 μm × 10 μm, 20 μm × 20 μm and 30 μm × 30 μm mesa areas, the 3-dB bandwidths are measured to be 32 GHz, 12 GHz and 6 GHz, respectively. Also we have obtained a dark current of 64 nA and a responsivity of 0.43 A/W at -4 V bias for 10 μm × 10 μm photodetector.
Two-photon laser scanning microscopy integrated with light stimulus system
We demonstrate a home-made two-photon laser scanning microscopy (TPLSM) with a light stimulus system. In this system, the femtosecond pulses are produced by a picosecond fiber laser with pulse width compression. A laser diode serves as stimulus, which modulated by an AOM and coupled into the same light path of a femtosecond laser. The control signal of AOM and trigger signal of two scanning mirrors are synchronized by a FPGA board. With modulating the intensity of CW laser at precise point in one scanning frame, any pattern of light stimulus can be delivered to the sample in real time.
Laser cleaning of the corrosion products on marine steels with spectroscopic control
The surface pretreatment of marine steel corroded by seawater is crucial procedure for the marine transportation and shipbuilding industry. This paper presents the laser cleaning of the corrosion products on marine steel using the pulsed fiber laser. The surface morphology as well as chemical composition of corrosion surface is compared with the cleaned surface. The Laser induced breakdown spectroscopy (LIBS) technology is used to guide and control the laser cleaning process.
Mechanism analysis of laser removal of metal oxide on the marine steel based on LIBS
Ang Zhang, Kuiguo Han, Qinhui Lu, et al.
The metal oxides of marine steel affect, the quality of welding seriously. The laser is used to remove metal oxides, and improve the surface properties such as interfacial bonding strength. However, the important part of laser removal of metal oxides is mechanism research. In this paper, in order to reveal the physical mechanism of laser removal of metal oxides, laser-induced plasma spectroscopy was used to collect the spectral information of laser removal of oxides from marine steel(Q235B). Temperature rise model of laser heating was used to analyze the spectral intensity of metal substrate and oxide. The intensity and electron density of the spectrum were studied, and the mechanism of laser removal was discussed.
Usefulness of the in vivo large field of view confocal line scanning ophthalmoscope in murine
Mouse is one of the most common animal models used in retinal researching, and obtaining its fundus images in vivo have significant significance for finding out formation and development mechanism of retinopathy, resolution and field-of-view are the key in fundus imaging. In this paper, we present an ophthalmoscope based on line scanning confocal technology, which utilizes one-dimension scanning line beam to increase image resolution and frame rate, it could capture mouse fundus at 1730*1730 μm field of view and 24 fps frame rate, retinal capillaries and vessels could be distinguished through reflectance and fluorescent images.
Influence and evaluation of vibrating screen methods on subjective speckle reduction
Yuan Yuan, Dongdong Wang, Dongzhou Wang, et al.
In this paper, we design a setting that could constantly monitor the screen vibration frequency and a speckle measurement system that simulates characteristics of human eye to record speckle images. Three vibrating methods, including acoustic wave vibration, frame vibration and chip motor vibration, are adopted to eliminate speckle. Speckle contrast, power consumption and noise are measured, separately. On our experimental platform, when the speckle contrast is less than 5%, the human eyes perceive free of speckle. By comparison, the chip motor vibration has optimal performance that the speckle contrast is 4.97%, power consumption is 1.51 W, and noise is 43.1 dBA. Therefore, the chip motor vibration method is the most suitable method for improving image quality in laser display.
Resistive switching memory devices based on all-inorganic perovskite CsPbBr3 quantum dot
All-inorganic perovskite quantum dots (QDs) have widely used in a lot of micro-nano photoelectric devices. However, resistive random access memory (RRAM) devices based on All-inorganic perovskite QDs are relatively scarce. In this work, a RRAM, which exhibits the write-once-read-many-times (WORM) memory effect, based on CsPbBr3 QDs was successfully fabricated by solution processed method at room temperature. The CsPbBr3 QDs based memory shows great reproducibility, good data retention ability, irreversible electrical transition from the high resistance state (HRS) or OFF state to the low resistance state (LRS) or ON state and the resistance ratio (ON/OFF) can reach almost 107. To study the CsPbBr3 QDs based WORM memory provides an opportunity to develop the next generation high-performance and stable WORM devices.
Design of a real-time laser stimulus system based on MEMS-based confocal laser scanning microscope
We design a real-time laser stimulus system for laser confocal scanning microscope. By introducing the FPGA and AOM to achieve high speed modulation of a scanning laser, we can adjust the laser lighting area freely. For reducing the size of the optical path, we use MEMS-mirror instead of traditional fast and slow axis mirrors. The size of MEMS-mirror is 1.5 mm diameter and the scanning frequencies are set 16 kHz and 12 Hz at the fast and slow axis, respectively. Our system is capable of delivering stabilized large stimulus pattern (up to 500 x 500 pixels) to the biological tissues.
Miniature vibration sensor based on a compact microfiber probe
Shijie Tan, Yanpeng Li, Tao Liu, et al.
A miniature vibration sensor based on a compact microfiber probe is proposed and experimentally demonstrated. The microfiber probe is simply fabricated by snapping a multimode biconical microfiber in the fused tapering process. Vibration causes periodic bending and axial extension of microfiber probe, resulting in the change of phase difference between fundamental mode and high-order modes. The vibration signal can be obtained by demodulated the reflected light signal with fast Fourier transform. The experimental result shows that the vibration sensor not only can exactly measure the frequency of the applied sinusoidal vibration signal, but also has a wide frequency measurement range of 20 Hz-2 kHz. The advantages of compact size and high accuracy make the vibration sensor have great application prospects.
A study on the photoresponse of three-dimensional reduced graphene oxide foams based field effect transistors
Graphene is a new type of two-dimensional (2D) nanomaterial composed of single-layer carbon atoms. It has high carrier mobility, good optical performance, good mechanical performance and thermal conductivity. Three-dimensional (3D) reduce graphene oxide (rGO) foam integrates the structure of 2D graphene with three-dimensional network connected structure of carbon nanomaterials, which is in a seamless connection possessing better optical and electrical properties. 3D GF has achieved some results in solar cells and supercapacitors, however, field effect transistors are rarely studied. In this paper, a kind of field effect transistor (FET) based on 3D rGO foam has been fabricated and its photoelectric response characteristics have been studied. The results show that an obvious photocurrent could be measured when the laser irradiate on the 3D rGO foams channel. The magnitude of the photocurrent can be effectively modulated by the back-gate voltage. The device exhibits a “V” shape transfer curves and stabile and reproducible photocurrent cycles. Particularly, a high photoresponsivity of 7.8 mA W-1 is achieved, which reveals 3D rGO foams a good candidate for photodetectors.
Simulation of single mode optical waveguide and Mach-Zehnder interferometer in deep-ultraviolet band
Ran Song, Lanting Ji, Juan Su, et al.
Deep ultraviolet (deep-UV, 200nm~300nm) spectrum analysis is an important technique in underwater biochemical sensors. For in-situ exploration, integrated optics based wavelength selective light source would have advantages in obtaining high sensitivity spectrum, compactness and low power consumption. The key components used in forming such wavelength selective light source are optical switch and bandpass filters. However, such optical switch and bandpass filter in deep-UV band have rarely been studied, to our best knowledge. In this paper, we proposed and designed a silica-based optical waveguide structure that can achieve single-mode transmission at 210nm-240nm. Furthermore, we designed and simulated a Mach-Zehnder Interferometer (MZI) switch in deep-UV band for in-situ marine chemical sensing application. In our simulation, a rectangular optical waveguide with single-mode operation has been achieved based on phosphorus (P) and boron (B) co-doped Silica core waveguide with 2.9μm in width and 0.35μm in thickness. The refractive index difference between core and cladding layer is Δn=0.003. Based on this waveguide structure, we also designed a Mach-Zenhder interference (MZI) type optical switch with extinction ratio larger than 26dB at deep-UV band.
High brightness narrow-stripe broad-area diode lasers at 976 nm
In this research, the transversal mode of 970 nm broad area laser diode based on a large optical cavity is studied. The vertical far-field patterns were measured to be dependent on the cavity caused facet loss. High-orders modes achieve lasing with higher facet loss while they can be completely suppressed by a low facet loss. The suppression of high-order modes was attributed to be an increase in the discrimination of differential quantum efficiency between high-order modes and the fundamental mode, which matches well with simulation. When the discrimination exceeds probable fluctuations, the high-order modes will be completely suppressed and lasing of single fundamental mode will achieve. According to our experiment results, the optimal resonance cavity length is about 6 mm in order to realize fundamental mode and simultaneously a high slope efficiency. As a consequence, high efficiency 970 nm broad area laser with slope efficiency over 1.07 W/A and full wavelength half maximum (FWHM) less than 2 nm@1A is demonstrated.
High-order transversal mode suppression by facet loss in 970nm broad area laser
In this research, the transversal mode of 970 nm broad area laser diode based on a large optical cavity is studied. The vertical far-field patterns were measured to be dependent on the cavity caused facet loss. High-orders modes achieve lasing with higher facet loss while they can be completely suppressed by a low facet loss. The suppression of high-order modes was attributed to be an increase in the discrimination of differential quantum efficiency between high-order modes and the fundamental mode, which matches well with simulation. When the discrimination exceeds probable fluctuations, the high-order modes will be completely suppressed and lasing of single fundamental mode will achieve. According to our experiment results, the optimal resonance cavity length is about 6 mm in order to realize fundamental mode and simultaneously a high slope efficiency. As a consequence, high efficiency 970 nm broad area laser with slope efficiency over 1.07 W/A and full wavelength half maximum (FWHM) less than 2 nm@1A is demonstrated.
Enhancement of surface plasmon resonance in a coupled graphene waveguide-cavity system
Graphene nanoribbons (GNRs) are envisioned to play an important role in improving confinement of surface plasmon resonance. Here, a coupled graphene-cavity-waveguide (GCW) system is proposed to investigate the characteristics of the resonant modes with finite difference time domain (FDTD) method. It is found that the surface plasmon characteristics can be modulated with the change of geometrical parameters of the structure and physical parameters of graphene. The resonant wavelength is sensitive to the Fermi level; and the resonant depth can be adjusted by the altering of carrier mobility. Moreover, the quality factor can be affected by the separation of cavity-cavity. The proposed GCW coupling system has potential applications in graphene-based integrated nanophotonic devices, optical filters, slow light and other active photonic devices.
Study on a photonic crystals stealth film for 1064nm laser and thermal infrared
In order to realize the laser and thermal infrared compatible stealth, a photonic crystal (PC) stealth film for 1064nm laser and mid-and-far infrared is designed by using the heterostructure method and characteristic matrix method. The results show that the reflectivity of this PC film at the wavelength of 1064nm is as low as 1%, meaning that it can reduce the reflectivity echo of 1064nm laser. In the meantime, the reflectivity of this PC film in 3-5μm and 8-14μm wavebands is 94.3% and 84.1% respectively, allowing the PC film to suppress the thermal radiation of the heat source. Furthermore, the impact of the incident angle on the reflectivity of the PC film is very small, whether in 1064nm wavelength or mid-and-far infrared wavebands. Therefore, this PC film can realize the compatible stealth of 1064nm laser and thermal infrared.
Periodical subwavelength light focusing by proximity projection grating structure
The authors developed a technique of generating periodical subwavelength light focusing array. In the technique, a proximity projection grating structure (PPGS) is employed. The size of focal spot obtained is dependent on the refractive index of film material used in the PPGS. When the film with the refractive index greater than 4 is used, focal spots with size of can be obtained. Additionally, the subwavelength light focusing will appear periodically along the propagation direction, which leads to the light focusing in both near field and far field. Both simulations and experiments verify the developed technique. The periodical subwavelegnth light focusing array has the potential in super resolution imaging applications.
Hybrid graphene/metal plasmonic fiber-optic sensing application
Sa Yang, Renlong Zhou, Yimin Liu, et al.
The paper proposes a graphene/metal sensing film assisted optical fiber as a graphene plasmonic waveguide biosensor. The enhanced graphene surface plasmon can promote the tunable sensitivities in both intensity and wavelength. The effective mode index, leakage loss and effective mode area properties for graphene/metal film assisted optical fiber are studied. There is a big interaction between raphene/metal sensing film and optical fiber in the region round wavelength 590nm. Graphene based hybrid plasmonic waveguide sensor can realize the highly sensitive, highly integrated, flexible, and miniaturized prospect in sensing application.
Second harmonic and sum frequency generation from nanostructured semiconductor film
Jie Zhan, Yichen Zhang, Lingxi Wu, et al.
We have studied analytically the second harmonic generation (SHG) and sum frequency generation (SFG) of the two surface plasmon (SP) resonance modes from sub-wavelength structured semiconductor film. The extraordinary Optical transmission of the fundamental light results from an enhancement of the local field. The strong local field induces an expected increase of second harmonic and sum frequency signals for the SP resonance modes. The increases of SHG and SFG are attributed to the structure-factor-induced surface SP resonance and the localized cavity SP resonance, respectively. The field distributions of fundamental light and their nonlinear signals are different for different SP resonant modes. The second-harmonic signal for the structure-factor-induced SP resonant mode seems the radiation of an electric monopole, and the sum frequency signal seems the radiation of an electric quadrupole. The method are useful for research of the nonlinear optical processes in graphene and black phosphorus SP.
Space Detection
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Flexible broadband optical frequency comb generation for dense wavelength-division multiplexing passive optical networks
In this paper, we compare and analyze some schemes of generating the optical frequency comb. We propose a flexible and low-cost broadband optical frequency comb for dense wavelength-division multiplexing passive optical network (DWDM-PON) system by using a CW laser and electro-optic modulators followed by a dispersion flattened high nonlinear fiber (DF-HNLF). The frequency spacing and center wavelength of the frequency comb can be flexibly adjusted by changing the radio-frequency signal and the output wavelength of a continuous-wave (CW) laser, respectively.
The influence of tracking divergence angle on far-field light correlation in optical communication
It is very critical to improve the tracking stability in inter-satellites optical communication. The definition of the far-field light correlation efficient as been proposed, and the mathematical model that between it and divergence angle of tracking beacon has been established due to correlation of bidirectional beams. The results showed that the light intensity in the far-field is decreasing and dispersing with an increasing divergence angle, but not has an increasing far-field light correlation.
Space-division multiplexing technology based on multi-core fiber and few-mode fiber in passive optical networks
We review space-division multiplexing passive optical networks (SDM-PONs) based on multi-core fibers (MCFs) and few-mode fibers (FMFs). We compare and analyze the characteristics in terms of MCFs and FMFs used in PONs. A scheme of MCF based SDM-PON with colorless ONUs without any signal processing technology is demonstrated, thereby achieving a low cost and making the system design much easier.
Applications
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Infrared small target detection algorithm based on potential regions proposal
A novel infrared small target detection algorithm based on potential regions proposal is proposed in this paper. Potential regions mean subsets (size are 16 by 16 in this paper) with small targets of an infrared image. A convolution neural network (CNN) classifier has been trained by using constructed datasets to discriminate potential regions of an input image. Traditional methods such as tophat transform, max-mean and max-median filter are used to suppress the background and noise of potential regions. Some experiments are carried out to verify the algorithm performance, and the results show that the gains of signal noise ratio and contrast ratio have better performance than traditional methods.
Combat effectiveness evaluation of air-crystal C4ISR early warning detection system based on improved ADC
With the reform of the new military revolution, the pace of war is accelerating, the operational environment is increasingly complex, and weapons and equipment are constantly being upgraded. How to scientifically and effectively evaluate the effectiveness of weapon systems is particularly important. In this paper, the aerospace C4ISR early warning detection system is taken as the research object, and the improved ADC method is used to evaluate its operational effectiveness. Firstly, the structure, mission requirements and functional requirements of the C4ISR early warning detection system are analyzed, and the operational effectiveness evaluation index system of the early warning detection system is constructed. Secondly, the traditional ADC model is improved by using information entropy and grey relational clustering method. The operational effectiveness of the C4ISR early warning detection system was evaluated. Finally, combined with an air defense brigade, the example application analysis and model validity verification were carried out, and relevant countermeasures and suggestions were provided for its system construction optimization based on the evaluation results.
Reliability analysis method of aerospace equipment system based on big data
Yufei Dou, Haihong Fang, Xiaoyan Ju, et al.
Aerospace equipment is developing in the direction of high speed, accuracy, stability and long life. However, the reliability and life expectancy of some equipment systems are still far from the world advanced level. The main reason is that the data volume is not complete enough, and the data format is single. In order to ensure the healthy operation of these equipment systems, it is necessary to use a large amount of data to diagnose and predict faults. Therefore, the research from simple data collection to the whole process analysis of big data is of great significance for equipment life assessment and reliability analysis. Based on the analysis of big data, this paper proposes a processing method for equipment fault diagnosis and prediction, which is carried out from the aspects of aerospace big data characteristics, data acquisition, data storage, algorithm model and prediction, from complex equipment operation. The fault information is discovered and analyzed to ensure the stable and safe operation of the entire system. Finally, we use the cloud service platform method to simulate the life of the equipment. Compared with the traditional method, the long-term memory network model has been added to predict the full life cycle of the equipment by more than 10%.
Research on trajectory optimization of powered flight for strong coupling and multi-constraints vehicle
Xue Kong, Guodong Ning, Ming Yang, et al.
An integrated trajectory optimization method for strong coupling and multi-constraints vehicle is presented. Based on the characteristics of strong coupling and multi-constraints, considering the change rate of angle of attack and safety margin of scramjet as additional constraint conditions and taking the minimum coupling degree as optimization index, the reference trajectory is adopted, which uses a smoothing method for solving multi-constraint s optimal problems. The reference trajectory can avoid the scramjet being in unsafe working condition to a certain extent, and also can greatly improve the accuracy of reference trajectory tracking. Based on the precise simulation model, the simulation analysis is carried out. The simulation results show that the method is effective and reliable.
Design considerations of the FBAR on-board test
With the increased performance requirements for film bulk acoustic resonator (FBAR) devices, accurate test of FBAR device parameters has become critical. The key of the FBAR on-board test is its test fixture structure and de-embedding methods. In this paper, the research status of FBAR board testing technology is reviewed. The parasitic effects, impedance matching and clamping design of the test fixture structure design process are discussed. The principle and error model of de-embedding and the advantages/disadvantages of each calibration method are analyzed. The accuracy of FBAR on-board test can be improved by reducing parasitic effects, optimizing impedance matching, improving calibration methods, and optimizing error model.
A new guidance superiority model for cooperative air combat
Bingsong Xiao, Weishi Peng, Rui Wang, et al.
A new guidance superiority model is proposed to solve the problem of selecting the fighter to guide missiles when the guidance power of missile is transferred in multi-fighter cooperative air combat. Firstly, the influence factors of guidance superiority under air-to-air condition are analyzed, including the detection capability of airborne pulse-Doppler radar for target, radar guidance link capability and missile pass back link capability. Secondly, the radar detection superiority model is presented using detection probability according to the radar-cross-section and ground clutter of targets in different situations. Thirdly, the guidance link dominance model and the pass back link dominance model under different situations are established based on the receiving power of guidance link and pass back link. Finally, the advantages of the three mentioned above are aggregated into the guidance superiority model. Simulation results show that the model is reasonable and effective.
Index-weight integration optimized by expert reliability
Faming L., Gang M., Di W., et al.
For the simplicity and utility, the traditional analytic hierarchy process (AHP) has been widely applied for multi-criteria decision-making. However, its index weight as well as the evaluation conclusion are still affected by the expert subjectivity. To solve this problem, our paper introduces the probability statistics theory to quantify the judgment qualities from different evaluation experts, and transforms the quantified qualities into expert reliabilities, and then optimizes the index-weight integration with the transformed expert reliabilities. Specifically, our method integrates the index weights with following steps. Firstly, using the traditional AHP, it calculates the evaluation values for all index weights according to each expert judgments respectively. Secondly, employing the probability statistics theory, it quantifies the judgment qualities from all experts. The quantified qualities are then transformed into expert reliabilities and expert weights. The transform rule is as followings: the larger reliability to those experts whose judgments have high quality, while smaller reliability to those experts whose judgments have low quality. Lastly, our method replaces the equal expert weight in the traditional AHP with the reliability-based expert weights. As a result, the expert subjectivity is decreased in the index-weight integration, and the evaluation conclusion becomes more creditable. The creditability is verified by experiments.
The application of intelligent modelling system in temperature compensation of SLD light source
Xian Chen, Jianhua Yang, Chunlin Zhang, et al.
The super luminescent diode light source (SLD) is an important component in fiber-optic gyroscope. And wavelength temperature stability is one of its key parameters. Effective temperature compensation system has been designed in previous works to stabilize its wavelength stability, which consists of driver module and thermal control module. For the driver module, temperature compensation model should be used to obtain stabilized current output. And for thermal control module, optical power change model is needed to obtain stabilized mean wavelength. Both models need to be well-established. In this work, intelligent modelling systems have been designed and realized for driver module and thermal control module. And fuzzy control algorithm is used for fine adjustment during modelling process. The intelligent modelling systems consequently improved the modelling efficiency and accuracy, and further improved the mean wavelength stability of SLD light source. Compared with traditional methods of mean wavelength drift suppression, after using the final model established by intelligent modelling systems, a wavelength stability improvement of one order of magnitude has been finally demonstrated.
Design of strapdown laser guided seeker
This paper proposes a design of strapdown laser guided seeker with large linear view field, low circuit noise and high precision algorithm. Simulation experiments show that the linear view field is ±12° in the range of ±15° view field, and the spot deviation is better than 1%. Combining traditional calculation method and polynomial fitting method, a fitting algorithm reduces root mean square error 76.9% than Gauss model method.
Vehicle recognition using multi-task cascaded network
Hua Gong, Yong Zhang, Fang Liu, et al.
Vehicle attribute recognition mainly contains two tasks: vehicle object location and vehicle category recognition. We propose a multi-task cascaded model MC-CNN, which integrates the improved Faster R-CNN and CNN. The first stage uses the improved Faster R-CNN network (IFR-CNN) to process the object location, and the second stage uses the improved CNN network (ICNN) to realize the object recognition. In IFR-CNN sub network, a max pooling and the deconvolution operation are added to the shallow layers of Faster R-CNN network. IFR-CNN can extract features from the different levels and increase the location information of shallow object. In ICNN sub network, we optimize the information extraction ability of high-level semantics in the middle layers and the deep layers of CNN network. The experimental results show that MC-CNN network proposed in this paper has better attribute recognition accuracy on BIT-Vehicle dataset and SYIT-Vehicle dataset than the single Faster R-CNN and CNN network models.
Improved electromagnetic wave propagation model on the South China Sea
We propose an improved electromagnetic wave propagation model on the South China Sea. The improved model is based on the SPM propagation model of the open ground, according to the characteristics of electromagnetic wave propagation on the sea, the effects of reflection loss and rain attenuation are added to the propagation model. After that, we use continuous wave (CW) test data of the South China Sea to correct the model parameters .The simulation results show that the proposed improved model is consistent with the sea surface test data, which can accurately simulate the electromagnetic wave transmission loss on the South China Sea and contribute to the scientific research of sea surface electromagnetic wave propagation.
Radio spectrum analysis of Qiongzhou Strait-Beibu Gulf
With the development of China's economy, the seaborne traffic volume along the Qiongzhou Strait-Beibu Gulf has been increasing. There is also a growing need to build ship networking to obtain data on ships, cargo, and navigational environments. However, China's unplanned spectrum resources are seriously insufficient. In this paper ,we set up a hardware and software measurement environment on this area to measure the occupancy of TV white spectrum. Then we perform time-space-frequency occupancy analysis of the measured data. The results show that there are a lot of continuous idle channels in the white spectrum of the Qiongzhou Strait-Beibu Gulf area, which can be used to construct maritime LTE ship network.
A method for determining the fusion trajectory parameters of optical measurement data
Wei Zhang, WeiHong Song, ShuHua Cui, et al.
For an optical measurement data location abnormal in aerospace Monitoring and Control network, Establish a fusion algorithm based on fuzzy support, combined with the measurement data of the same arc tracking device. This method can effectively calculated the contribution of dynamic weight value, Through reasonable weight distribution, the accurate determination of flight target parameters can be achieved, and the impact of abnormal data on ballistic parameters is avoided, and the characteristics of flight targets are actually described. By application , this method overcomes the weight arithmetic mean method, such as the disadvantages of ballistic parameters is still abnormal after fusion, reduce the uncertainty of the ballistic parameters, restrain the deviation and improve the accuracy of data processing.
Study on airborne opto-electronic image and three-dimensional spatial data fusion
Qiang Gao, Ming Ji, Ying He, et al.
Based on the analysis of the existing image and spatial data fusion methods, a new method of integrating real-time image and 3d digital map of photoelectric sensor in the airborne field is proposed. This method can realize the fusion of 2d photoelectric images into 3d terrain space, and the combination of real-time high resolution photoelectric images and digital maps can directly reconstruct the surrounding environment of the aircraft and reduce the workload of pilots, or facilitate the analysis process of intelligence analysts. It has certain application potential in precision strike field.
Cold-thermal wake characteristics of submarine in temperature-density stratified seawater
Xusheng Zhang, Liang Guo, Richa Hu, et al.
In this paper, the three-dimensional calculation model of 1/72 LSII submarine is established by finite volume method, and combining frame motion, user-defined function and polynomial profile, the simulation of propeller rotation and temperature-density stratified seawater are realized. Based on this model, the effects of diving depth, sailing speed and wake velocity on cold-thermal wake characteristics are analyzed. The conclusions are as follows. 1) Considering the temperature-density stratified seawater is a sufficient and necessary condition for simulating the cold-thermal wake characteristics of submarine. 2) Submarine perturbs the low-temperature seawater to form the cold wake, then the cold wake and the thermal wake are superimposed to form the cold-thermal wake characteristics in downstream sea-surface. 3) Cold wake characteristics of upstream sea-surface are related to the diving depth directly, but aren’t related to the sailing speed and wake velocity. The contents above could provide reference for the high-precision simulation of submarine’s cold-thermal wake characteristics.
Simulation analysis of signal-to-noise ratio of the underwater range gating imaging system
Dongdong Jin, Chunhen Ji, Xinbo Chu, et al.
Laser range gating imaging is currently the main means of underwater optical remote detection. The imaging signal-to-noise ratio is the core indicator of the distance gating system, which directly determines the limit detection distance of the system. In this paper, the imaging signal-to-noise ratio of the distance gated imaging system is theoretically analyzed. Based on the theory of laser transport in water, the time and space broadening effect of laser transmission, backscattering and imaging optical modulation transfer function(MTF) decline are all considered. Finally, the final form of the signal-to-noise ratio(SNR) and the simulation results are given.
Analysis of mode instability in DFB fiber laser hydrophone array
In order to increase the multiplexing capacity and optimize the noise level and power of distribute feedback fiber laser hydrophone array, the factor of the mode instability has been studied. Mode instability characteristics of DFB fiber laser hydrophone due to multiple external reflections is modeled, and the dependent condition and suppression method of DFB fiber laser array is carefully analyzed. It can be concluded that the mainly reason for the mode instability of the DFB fiber laser hydrophone array is related to the mode splitting caused by external cavity feedback light reflected by the fiber connector, and the reduction of fiber flange connector reflectivity can effectively suppress the mode instability.
Erratum
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A study on the photoresponse of three-dimensional reduced graphene oxide foams based field effect transistors (Erratum)
A revised version of this manuscript was published on 1 December 2020. Figure 1(b) and its explanation have been corrected. Acknowledgements have been added to the paper. The original paper has been updated.