Infrared and Laser Engineering
Co-Editors-in-Chief
Feng Zhang
Bin Ma, Jiaqi Han, Ke Wang, Qiushi Huang, Hongfei Jiao, and Shuang Guan

Thermo-mechanical damage occurs when a metal film layer is irradiated by a high-power nanosecond pulse laser. High temperature and high pressure induce the thermal evaporation of the metal film layer and particles outward ejection. Most of the ejected particles are in atomic and ionic states. In the energy dispersive spectroscopy analysis test, multiple sets of standard samples for comparison experiments was used to calibrate the test results in this paper, and an estimated method was given to calculate the number of deposited atoms based on the results. The differences of the eruption of Al film under different vacuum environments and atmospheric environments irradiated by different laser fluences were compared. And the eruption and spatial distribution characteristics of metal films with different melting points were compared. The experimental results were further analyzed and explained by combining the transient images captured by pump-probe technology.

Nov. 25, 2021
  • Vol. 50 Issue 11 20210036 (2021)
  • Xuehai Zhang, Heli Wei, Jinlong Duan, Weidong Li, Shuguang Zou, and Congming Dai

    The complex mixing state of sulfate and mineral dust particles is formed through a series of chemical reactions, which bring great difficulties to understand the optical properties of atmosphere aerosols during haze episodes. Therefore, it is of great significance to clarify the influence mechanism of sulfate core on the optical properties of mineral dust particles. In this paper, a "core-shell" ellipsoidal structure model of dust and sulfate (D-S) aerosols was established based on the actual haze conditions according to mixing structure change in the action process between sulfate and mineral dust particles. The influence of mixing ratio on the optical properties of monodisperse dust-sulfate particles at four selected wavelength (0.44, 0.675, 0.87 and 1.02 μm) was studied by using the T-matrix method. The results show that the influence of mixing ratio on the optical properties of D-S particles is mainly in the Mie scattering region, while the effect of mixing ratio is not obvious in the Rayleigh scattering region. When the mixing ratio is less than 0.3, the sulfate shell plays a dominant role in the particle scattering characteristics, while the mixing ratio is greater than 0.7, the particle scattering characteristics are mainly affected by the dust core. In the range of 0.3-0.7, the scattering characteristics are influenced by D-S, and maybe stronger or weaker than any kind of pure particles. The research is of great significance to understand the mixing structure and optical properties of individual aerosol particles during haze aging process.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210052 (2021)
  • Bin Hu, Chuang Li, Meng Xiang, Liangliang Li, Haobin Dai, Pei Yao, and Xuyang Li

    In order to obtain higher angular resolution, the aperture of the space optical telescope is getting larger and larger, and the space telescope with aperture of more than four meters will be difficult to break through the limitation of the effective envelope of the fairing of the existing launch vehicle. On the other hand, the micro-nano optical remote sensing satellite, which has great advantages in terms of development cycle and cost, also has extensive requirements for improving spatial resolution and light gathering area, requiring a smaller launch volume to accommodate a large opto-mechanical system to reduce the launch cost. Deployable space telescopes will be a feasible solution to overcome the limitations of launch size. The research status of deployable space telescopes was reviewed from the aspects of large aperture space astronomical telescopes, segmented mirror deployable telescopes for earth observation and micro-nano satellite optical telescopes deploying along optical axis. Some key technologies and development trends involved in deployable space telescopes were described and summarized.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210199 (2021)
  • Zhiqi Zheng, Yongqiang Pan, Huan Liu, Weirong Yang, Ziyang He, Dong Li, and Zelin Zhou

    In order to obtain the optical constants of infrared low refractive index materials, single-layer yttrium fluoride (YF3) and ytterbium fluoride (YbF3) thin films were prepared on multispectral zinc sulfide substrates by electron beam thermal evaporation technique at different substrate temperatures. Spectrophotometer and Fourier transform infrared spectrometer were used to test the transmittance spectra of the optical parameters from visible to far-infrared bands, and the refractive index and extinction coefficient in the band of 0.4-14 μm were obtained by using the combination of envelope method and dispersion model fitting. The accuracy of the optical constants of YF3 and YbF3 films in the band of 0.4-1.6 μm was verified by the ellipsometry test results. The obtained optical constants were substituted into the TFCalc film design software, and the calculated transmittance spectrum curve of the monolayer film was in good agreement with the measured spectrum curve. The experimental results show that the optical constants obtained by this method are accurate and reliable in the ultra-wide spectral range of 0.4-14 μm.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210371 (2021)
  • Sai Yan, Xin Xie, and Xiulai Xu

    With the development of topological photonics, topological lasers and semiconductor lasers are promoted by the discovery of the topological edge states and corner states with robustness against defects and perturbations. Firstly, the development history of the topological lasers and the principles of the various kinds of topological lasers was reviewed; Secondly recent realizations of various topological lasers were analyzed and the basic physics about topological edge states and topological corner states was explained. In these experiments, the modes of topological laser were decided by the dielectric structure. The laser was excited by pumping the photonic gain. The analysis show that topological lasers based on topological corner states have higher efficiency and lower threshold than those based on topological edge state, due to the high quality factor and small mode volume of topological corner state, which provides the possibility for future photonic integrated chip. Finally, the challenge and potential applications in the future were outlooked, which was beneficial to explore practical topological laser.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210506 (2021)
  • Haojing Chen, and Yunfeng Xiao

    Precision measurement is a cornerstone of modern physics, and the development of laser sources directly promotes the progress of science and technology. In the early 21st century, the invention of the optical frequency comb created the optical atomic clock, the most accurate time/frequency standard device, a lot of precision measurement applications have been implemented, including absolute optical frequency measurement, fundamental physical constants measurement, precision distance measurement and molecular spectroscopy measurement. However, the early comb systems were complex and expensive, and worked in large laboratories, which restricted their application scenarios. In recent years, an integrated microresonator-based optical frequency comb (microcomb) has attracted great attention from the scientific and industrial communities because of its advantages such as compact size, low power consumption and excellent scalability. Different from traditional optical frequency combs, which rely on gain media or saturable absorbers to realize the mode locking, this kind of integrated microcomb benefits from the enhanced nonlinear effect of high-quality factor microcavity to realize the excitation and mode locking of the frequency comb. This new mechanism greatly reduces the volume and cost of optical frequency combs, which has great advantages in civilian-based precision measurement applications. The progress of integrated microresonator-based optical frequency combs in precision measurement applications is introduced, which mainly focuses on miniature optical atomic clock, ultra-fast precision distance measurement and high-precision spectroscopy in this paper. Finally, the opportunities and challenges in the future application of integrated microresonator-based optical frequency combs in precision measurement are summarized and prospected.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210560 (2021)
  • Zeyang He, Huiping Deng, Sen Xiang, and Jin Wu

    Light field image depth estimation is a critical technique in applications such as light field 3D reconstruction, target detection and tracking. The refocusing property of light field image provided rich information for depth estimation, however it was still challenging in the case of occlusion region, edge region, noise interference, etc. Therefore, a depth estimation algorithm based on the consistency of epipolar plane image (EPI) slant pixels and the difference of epipolar plane image regions was proposed to solve the occlusion and noise problems. The consistency of EPI slant pixels was adopted by the spinning linear operator (SLO) color entropy metric, which could improve the accuracy of depth map edges as well as the noise immunity; the difference of EPI regions was measured by the chi-square χ2 metric of the spinning parallelogram operator (SPO), which could improve the accuracy of the depth gradient area of the depth map,and the two metrics were fused with confidence weighting, which could reduce the interference of occluded regions and noise. In addition, the color similarity of the pixel neighborhood was fully utilized, and post-processing was performed with a guided edge-preserving filter and Markov random field (MRF) global optimization strategy to further reduce the edge error of the depth map to obtain an accurate depth map with occluded edges. Experiments were conducted on the HCI light field data set and compared with the classic light field depth estimation algorithm. The results show that the algorithm has a significant improvement in both subjective quality and objective indicators.;that the proposed method outperformed state-of-the-art depth estimation methods. Compared with the classical light field depth estimation algorithm, proposed method had significant improvement on both subjective and objective qualities.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210021 (2021)
  • Ning Li, Daozhi Wei, Dongyang Zhang, and Liangfu Yao

    In order to improve the detonation control accuracy of the air defense missile fuze, that is, to obtain a more accurate detonation delay time, an integrated information fusion method for the measured data of infrared imaging seeker and laser rangefinder based on particle filter was proposed. When processing multi-mode information, the measurement data of the two sensors are not on the same time reference due to the different power-on time of different sensors and the difference in sampling frequency. Therefore, the typical missile target rendezvous scenarios were chosen, for the high-frequency sampling of the laser rangefinder and the low-frequency sampling of the infrared seeker, a time alignment method based on linear interpolation was used to apply the measured data to the calculation of delay time model. On the basis of this model, a centralized data filtering algorithm for integrated sensors based on particle filtering was proposed. It is obtained through a comparison simulation experiment with the traditional extended Kalman filtering algorithm: the measurement accuracy of detection angle and azimuth angle are greatly improved under this information fusion method, and the accuracy of detonation delay time is also improved, which verifies the effectiveness of the data fusion method proposed in this paper.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210039 (2021)
  • Zhenyue Zhu, Shujing Lv, and Yue Lv

    Automated security inspection is an effective measure to maintain public safety and improve the efficiency of security inspection. Usually, it is difficult to obtain enough labelled samples which contain some prohibited items of rarely appearing. Furthermore, the category of prohibited items varies in different scenarios and security levels. A graph matching network algorthm for few-shot prohibited item segmentation was introduced to deal with the imbalance of training samples faced by neural network methods, and to inspect prohibited items of new categories without the requirement of retraining. This model parallelly input a query image and several support images into the graph matching network, and segmented the prohibited items from the query image according to the matching results. The graph matching module not only considered the matching problem from the point of node similarity between two graphs, but also establisheed a global concept to match the graphs with the use of DeepEMD algorithm. Experiments on the SIXray dataset and Xray-PI dataset show that proposed model achieves 36.4% and 51.2% meanIoU for 1-shot tasks and outperforms the state-of-the-art method by 2.5% and 2.3% meanIoU, respectively. The extended experiments demonstrate that propoed algorithm can effectively improve the accuracy of few-shot X-ray image segmentation.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210075 (2021)
  • Wenfeng Guo, and Zhigang Jiao

    In the process of infrared imaging, target edge blurring is a key factor that affects the effect of infrared target recognition, and it is also the focus of infrared target recognition algorithms. Therefore, reasonable compensation of target geometric feature information in spectral images has become one of the research hotspots.The bounding box containing the geometric feature information of the target was used as a constraint condition, and the infrared spectrum image was hierarchically limited and filtered to reduce the loss of the target geometric shape data in the original image data and improve the recognizability of the target. A spectral clustering algorithm under bounding box constraints was designed. The parameter η was set to characterize the geometric information of the military vehicle target under test, and the parameter m was set to characterize the spectral feature information of the military vehicle target under test. In the experiment, a TEL-1000-MW infrared imaging spectrometer was used to obtain multi-spectral images. By changing the m and η values, the number of spectral feature values and the bounding box range were adjusted to obtain different target recognition images. Compared with the traditional method for the recognition effect of the same infrared target image, it was found that the geometric boundary information retention effect of the target image under test using the bounding box constraint was significantly better than that of the traditional method. When m=10, η=0.7, the infrared image target recognition effect was the best, and the algorithm convergence speed was also the best. It can be seen that the algorithm has high practical value in improving the ability of infrared target recognition and avoiding false targets and missed targets.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210085 (2021)
  • Wei Wang, Dehai Xu, and Mingyi Ren

    For infrared image, how to enhance the detail and suppress the noise while compressing the dynamic range is an important issue. An improved infrared image adaptive enhancement method was proposed. Firstly, a parameter adaptive guided image filtering method was designed, based on the guided image filtering, the original infrared image was divided into the basic layer and the detail layer; based on the gray distribution, a new histogram projection method with adaptive threshold was designed to compress the dynamic range and enhance the contrast of the basic layer; then the linear coefficient of the adaptive guided filter was used to enhance the detail layer and suppress the noise; finally, the enhanced infrared image was obtained by adaptive fusion of the enhanced basic layer and detail layer. The experimental results show that compared with several good algorithms, such as the contrast limited adaptive histogram equalization and the detail enhancement for high-dynamic-range infrared images based on guided image filter, the proposed algorithm processed image detail is richer, noise suppression effect is stronger, better visual effect, and the algorithm is more flexible, without adjusting parameters to deal with a variety of scenarios.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210086 (2021)
  • Xiuhua Zhang, Hanyu Hong, Yangyang Xu, and Tianxu Zhang

    Automatic ore screening is one of the key links to improve the efficiency of mineral resources processing. Aiming at the complex and changeable illumination in the ore mining site, it is difficult to detect the ore in the conveyor belt automatically in real time, and so on, a real-time 3D vision screening method based on infrared structure light was proposed. In order to solve the interference of solar radiation on the surface structure light imaging of ore under complex illumination, the infrared structure light near 800 nm was used as the active light source to obtain stable structural light images of ore surface under various illumination conditions. The method of neighborhood cumulative difference feature analysis was proposed. The center of structured light strip was extracted by locating the boundary point of strip quickly, and then 3D coordinate data of ore could be obtained in real time. The results show that the proposed method can better adapt to the changes of the shape and direction of the line structure light and the stability of the method. The time for screening of light images of each ore structure is 13.2 ms, which meets the 3D real-time screening requirements of the ore on site.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210125 (2021)
  • Lu Zhao, and Sen Xiong

    With the improvement of the performance of infrared sensors and the popularization of applications, it becomes possible to obtain multi-view images of the same target in the same scene. Therefore, a target recognition method combining multi-view infrared images was proposed. First, the clustering analysis on multi-view infrared images was performed to obtain multiple view-view subsets. In each view subset, the infrared images shared high correlations. For different view subsets, they were relatively independent. In order to make full use of the correlation and independence, the joint sparse representation (JSR) was used to make decisions on single view subsets. In particular, for the subset with only one view, the classical sparse representation-based classification (SRC) was directly used for decision. For the decision results obtained by different view subsets, the fusion processing was carried out based on the idea of linear weighting. And the target category was determined according to the fused results. Therefore, on the basis of analyzing the inner correlation of the multi-view infrared images, the proposed method separately examined the local correlations and overall independence, and integrated them through the fusion on the decision-making layer, which improved the reliability of the final decision. Experiments were performed on the collected infrared images of multiple types of traffic vehicles. The proposed method was tested and verified on the original, noisy, and occluded samples. The effectiveness of the proposed method is verified by comparison with other methods.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210206 (2021)
  • Saiwen Zhang, Yaqi Deng, Chong Wang, Xiaoling Leng, Guangfu Zhang, Bing Wen, Yangbao Deng, Weishi Tan, Ye Tian, and Wenguo Li

    In the super-resolution microscopy imaging technology, single molecule localization microscopy is one of the widely used techniques. In this paper, in order to achieve super-resolution fluorescence image reconstruction, a multiple measurement vector Compressed sensing (MMV-CS) model was established based on the principle of fluorescence microscopic imaging, and the multiple sparse Bayesian learning algorithm was applied in problem solving. The effects of the effective pixel size, the number of photons generated by fluorescent molecules and the Poisson noise of fluorescence and background signal on the reconstruction results were analyzed. The running time of the algorithm was analyzed with the image subdivided into smaller patches. The results of simulation and experimental calculation show that when the standard deviation of the point spread function is 160 nm, the effective pixel size at 120 nm, 160 nm and 200 nm can achieve good reconstruction effect, while the pixel size at 60 nm results in poor effect. Better reconstruction image quality is achieved with more photons collected by the detector. As the background signal photons increase, the sample structure becomes indistinguishable when the distance is too close. Under the same subdivided condition, MMV-CS is one order of magnitude faster than the Homotopy (L1-H) algorithm and three orders of magnitude faster than the convex optimization algorithm (CVX), which has greater advantages in terms of running time for the application of MMV-CS in 3D super-resolution fluorescence microscopy.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210484 (2021)
  • Xu Liu, Yunduo Li, Lianhua Ye, Zhangcheng Huang, Songlei Huang, and Jiaxiong Fang

    Single-photon detection has important application prospects in quantum information, biomedicine and laser radar 3D imaging. InGaAs Geiger avalanche focal plane has single-photon sensitivity. Distance detection is achieved by measuring time of photon flight. Time-to-digital conversion accuracy determines the ranging accuracy of the detection system and this direction is the focus of single photon detection in recent years. A high resolution and low error rate 64×64 array type pixel level time-to-digital converter (TDC) circuit adopting three-stage asynchronous periodic counter structure was designed for InGaAs Geiger-mode avalanche focal plane array applications. Sub-nanosecond time resolution was realized by a voltage-controlled delay chain as well as a fine TDC that was shared by the entire array. The pixel level middle and coarse TDC used a divider counter to reduce the clock frequency and a linear feedback shift register to achieve a large time range, respectively. The high-segment coarse TDC can achieve timing, data storage and output integration through the register chain. The data conversion error rate originating from the mismatch of counting clocks between different stages was significantly reduced by incorporating of a delayed sampling scheme. A timing resolution of 0.5 ns at a reference clock frequency of 250 MHz, an integral nonlinearity of -0.4 to 0.6 LSB, a differential nonlinearity of -0.4 to 0.4 LSB, an effective digit of 13 bits, and a power consumption of 380.5 mW at 20 kHz frame rate are attained based on a 0.18 µm digital-analog hybrid CMOS technology. The TDC remains monotonous within the conversion range.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210009 (2021)
  • Xin Wu, Youli Wu, Deqing Niu, Tongxin Liu, Yuxuan Cai, and Rui Xu

    In order to improve the objectivity and accuracy of infrared anti-jamming evaluation, aiming at the problem that the subjective factors of discriminant matrix are too strong in the process of evaluating infrared anti-jamming ability by analytic hierarchy process (AHP), an infrared anti-jamming evaluation method based on principal component-analytic hierarchy process was proposed. Firstly, the correlation coefficient matrix between indexes was solved by principal component analysis (PCA), and the index of average influence degree was put forward. Then, through this index value, the discriminant matrix was adjusted according to the established adjustment rules. Finally, using the infrared anti-jamming simulation data, combined with the adjusted discriminant matrix for AHP, the principal component-analytic hierarchy process infrared anti-jamming evaluation model was established. The simulation results show that the model can better evaluate the evaluation results of infrared countermeasure in the corresponding jamming environment, there is a negative correlation between the confrontation result and the evaluation score. The score is bounded by the E=1.0, and the evaluation results of missile hit are all above the average. The evaluation result of infrared anti-jamming under this countermeasure condition can be observed intuitively.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210060 (2021)
  • Zhenxiang Wang, and Kai Hu

    With the increased demand for long-range imaging systems such as remote sensing and satellite imaging, scanning type infrared sensors have been deployed extensively. To alleviate the problem of relatively poor SNR that would affect the image quality, a readout circuit with a time-delayed integration (TDI) technique was proposed and described. The readout circuit consisted of capacitor trans-impedance amplifier (CTIA) pixel circuits, paralleled TDI stages, multiplexer, and output buffer. CTIA based analog front-end circuit with optional gain and less than 0.3% nonlinearity was designed for processing large range photocurrent. The chip was manufactured with a 0.35 μm CMOS process and occupied an area of 1.3 mm×20 mm. With the 5 V power supply, the power consumption was less than 60 mW. To evaluate the function of the 1024×3 TDI readout circuit, different voltages were injected into three terminals and the output from the TDI stage was captured. The measurement results validate the proposed design successfully.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210072 (2021)
  • Jiasheng Cao, Tao Li, Hongzhen Wang, Chunlei Yu, Bo Yang, Yingjie Ma, Xiumei Shao, Xue Li, and Haimei Gong

    In order to obtain low-noise InGaAs focal plane arrays, it is necessary to adopt high-quality InGaAs material with a low unintentionally doping concentration(u-InGaAs) to fabricate the detector. Zn diffusion with sealed-ampoule method on the lattice-matched InP/In0.53Ga0.47As hetero-structure with a u-InGaAs absorption layer was carried out. And the Scanning Capacitance Microscopy (SCM) technology were used to study Zn diffusion in these samples. The results show that the junction depth increases significantly with the increase of diffusion temperature and time. The diffusion interface of materials with a u-InGaAs absorption layer tends to change slowly compared with relatively high concentration materials (5×1016 cm-3). According to the experimental results, the diffusion coefficient of Zn into InP under 530 ℃ is figured out, which is 1.27×10-12cm2/s. The Microwave Photo Conductivity Decay method (μ-PCD) is used to extract the minority carrier lifetime of the InGaAs absorption layer. The measured minority carrier lifetime is 5.2 μs. Response distribution of devices with a u-InGaAs absorption layer at room temperature were studied by Laser Beam Induced Current technique (LBIC). The results show that the effective optically sensitive area increases significantly. The minority carrier diffusion length LD is 63 μm by fitting the experimental data, which is consistent with the theoretical calculation. The dark current density of the device with a u-InGaAs absorption layer is 7.9 nA/cm2 at room temperature, and the activation energy Ea is 0.66 eV. By fitting the dark current composition of the device, the minority carrier lifetime τp of the absorption layer of the device is about 5.11 μs, and the fitted minority carrier lifetime is consistent with the measured minority carrier lifetime.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210073 (2021)
  • Yuheng Wang, Honghu Ji, Wen Cheng, and Jiquan Li

    In order to investigate the aerodynamic and infrared characteristics of serpentine 2-D convergent-divergent exhaust system, three serpentine 2-D exhaust system with right behind full-shield convergent-divergent nozzle were designed. The effect of centre line offset-diameter ratios between throat and outlet, (S8-S9)/D=0.26-0.3, and width expansion ratios between throat and outlet, (W9-W8)/D=0.1-0.36, on aerodynamic and infrared characteristics was studied numerically. The results show that relative to the axisymmetric exhaust system, the infrared radiation intensity of three serpentine 2-D convergent-divergent exhaust systems decrease by 73.4% on average in the range of 0°-15° for tail direction, and decrease at least 60.3% in the 90° direction of side, upper, lower detection plane, the decrease of infrared radiation characteristics increases with the decrease of (S8-S9)/D, increases with the increase of (W9-W8)/D, and more sensitive to (S8-S9)/D. The thrust coefficient of three serpentine 2-D convergent-divergent exhaust systems increases with the decrease of (S8-S9)/D and (W9-W8)/D.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210084 (2021)
  • Weiping Wang, Jiarui Yu, Xiaoyan Hu, and Shaoyu Zhao

    Mid-infrared integrated polarization focal plane detection technology, which combines polarization detection technology and mid-wave infrared focal plane imaging detection technology, has realized the monolithic integration of polarization grating and detector through heterogeneous integration, and has the advantages of small size, light weight, high mechanical stability and simultaneous imaging of multiple polarization directions. Pixel-level sub-wavelength metal gratings can achieve high extinction ratios in different polarization directions. However, the selection of metal material and the structural parameters of gratings such as pitch, duty cycle and thickness have a significant impact on the polarization performance. The theoretical analysis of the sub-wavelength metal grating was given, and the polarization performance simulation model of the mid-wave infrared integrated polarized HgCdTe detector was established, and the effects of different grating parameters on the polarization performance were analyzed. The optimal structural parameters of 200-400 nm Al grating pitch, 0.5-0.7 duty cycle, and over 100 nm thickness were determined by simulation. The simulation results show that the range of ±14° incident angle had a small effect on the polarization extinction ratio. Meanwhile, Si-based HgCdTe detector had been introduced. The influence of SiO2 antireflection film thickness on polarization extinction ratio had been simulated to determine the optimal thickness. Compared with Cadmium Zinc Telluride (CdZnTe) substrated polarization HgCdTe detectors, the polarization performance of Si-based detector has been proved better. The simulation results can provide theoretical guidance and reference for the design of the polarization grating of the mid-wave infrared integrated polarization HgCdTe detector.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210132 (2021)
  • Yanwei Li, Qingjing Gao, Haodong Wei, and Jiangtao Li

    Aiming at the infrared imaging guidance system with good maneuverability and strong penetration ability, a new type of infrared interference method was proposed by using the characteristics of ultra-thin metal sheets that can quickly heat up and naturally cool down. A mathematical model of the heating and natural cooling process of the metal sheet was established, and the structure and material of the metal sheet were determined; the infrared interference device with a simple structure and a good sealing environment was designed. The test results indicate that the nickel sheets is the best material. The heating time is 50 ms (500-1 000 ℃), and the natural cooling time is 75 ms (1 000-500 ℃), which meet the frame rate requirement (10 Hz). And the regular periodic change of temperature is realized. The analysis and test results confirm that the device can simulate the rapid changes of infrared radiation characteristics, and could provide a new idea for interference in the terminal guidance phase.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210218 (2021)
  • Shuai Wang, Qin Han, Han Ye, Liyan Geng, Ziqing Lu, Feng Xiao, and Fan Xiao

    Single-photon detectors for the near-infrared wavelength region are receiving widespread attention in an increasing number of photon counting applications. In fields such as quantum information processing, quantum communication, 3-D laser ranging (LiDAR), time-resolved spectroscopy, etc. An InGaAs/InP single photon avalanche diode (SPAD) was designed and demonstrated to detect 1 550 nm wavelength photons in this paper. The SPAD has a separate absorption, grading, charge and multiplication region structure (SAGCM) with single photon sensitivity when working in Geiger-mode. The characterization of the SPAD include breakdown voltage, dark count rate, single photon detection efficiency and after pulse probability as functions of temperature from 223 to 293 K. The 25 μm diameter SPAD shows certain temperature dependency, with breakdown voltage dependence of approximately 100 mV/K. Operating at 223 K and in Geiger-mode, the SPAD achieves a photon detection efficiency of 21% at 1 550 nm with a dark count rate of 4.1 kHz and a after pulse probability of 3.29%. The source and physical mechanism of the photon detection efficiency, dark count rate and after pulse probability of the SPAD with temperature dependency were also analyzed and discussed. The mechanism analysis, discussion and calculation can provide more theoretical basis and support for the design and fabrication of SPAD.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210453 (2021)
  • Long Li, Qiujuan Zhang, Chunling Zhang, and Yiran Yang

    In order to reduce the thermal effect of Nd:YAG ceramic laser side-pumped by pulsed laser diode bar, improve the stability of resonator and improve the performance of laser, the temperature rise and thermal deformation field generated by pulsed laser diode bar side-pumped laser ceramic were studied analytically by using the heat conduction theory. Based on the analysis of the working state of the laser ceramic side-pumped by pulsed laser diode bar, a thermal analysis model suitable to the actual situation was established, and the general analytical expressions of the temperature field and thermal deformation field in the pumping period and the pumping interval were obtained by solving the Poisson equation of heat conduction. The three-dimensional temperature field distribution of Nd:YAG ceramics pumped by the side of pulsed diode bar, the temperature field distribution in the process of repeated pulse pumping, and the influence of different pumping parameters on the temperature field were analyzed quantitatively. The thermal shape variables on the pump surface were analyzed quantitatively when the thermal dynamic equilibrium was reached. Calculation results show that: when the pump power is 60 W, repetition frequency is 100 Hz, beam waist radius is 150 μm, neodymium ions doped mass fraction is 1.0%, the Nd:YAG ceramic pump surface produces temperature rise of 29.6 ℃, pump surface and smooth surface produce 0.95 μm and 0.99 μm hot shape variables. The analytical method of temperature field of laser ceramics solves the problem of low accuracy caused by numerical analysis method, and it can also be applied to other thermal problems of laser system, which provides a theoretical basis for reducing the thermal problems in laser system.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20200495 (2021)
  • Chenyang Zhang, Chunhui Wang, Lan Zhan, Ming Qi, and Shuo Jiang

    The spaceborne micropulse photon-counting lidar can realize high repeat frequency and multi-beam detection for the ground targets, improve the sampling density and coverage width of lidar in-orbit measurement effectively, meet the high-efficiency and high-precision surveying and mapping requirement. The simulation model was established based on the multi-pixel photomultiplier tube (PMT) considering the working principle of micropulse photon-counting lidar. Then the typical detection process of the micropulse photon-counting lidar was analyzed. The results show that the increase of pixel of PMT can obviously decrease the first photon effect of the lidar, improve the ranging accuracy. The ranging standard deviation of lidar would increase obviously with the increase of terrain slop. In addition, the distribution characteristics of the terrain profile can be described more accurately by the photon-counting point cloud with the increased number of pixel and arriving photons. Meanwhile, the airborne flight test verifies that the numbers of effective echo photons points increase obviously with the increasing pixel of PMT, which can reflect the contour features of tested terrain more accurately and efficiently. It can realize the high-precision photon-counting ranging under the complicated terrain, verify the correction of the simulation analysis result.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20200502 (2021)
  • Chen Wang, Xu Liang, Ying Lin, and Xiaodong Fang

    A fully isolated, high-precision synchronous trigger system with MOPA structure of excimer laser was introduced. Firstly, the phase-locked loop phase shift technology combined with the traditional pulse counting method was proposed to realize the high resolution and large range of the system; Secondly, the full electrical isolation way was used to achieve long-term stable operation and real-time control of the system in a complex electromagnetic interference environment. The main parameters of the system reached a resolution of 1 ns, a delay and pulse width adjustment range of 0-325 μs, the jitter between each channel was less than 60 ps, and the front and back edges were less than 1.5 ns. Synchronous trigger system applied to a set of 193 nm deep ultraviolet MOPA structure excimer laser device. It realized the precise real-time control of MOPA dual cavity discharge sequence under the high repetition frequency of 4 kHz, the relative discharge delay can be strictly controlled in the best time period, the discharge timing jitter was less than ±4 ns, and the pulse energy amplification of the MO cavity seed light was successfully obtained by the PA cavity. The magnification rate reached 19.2, and the maximum output pulse energy reached 7.1 mJ. It meets the needs of deep ultraviolet lithography applications.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20200516 (2021)
  • Hui Chen, Zhenxu Bai, Jiancai Wang, Bingyuan Zhang, and Zhen'ao Bai

    Picosecond pulse laser with high average power is critical to applications such as industry processing, space exploration, etc. However, due to the narrow pulse width and low single pulse energy, the mode-locked picosecond seed light is difficult to be amplified directly through the traditional traveling-wave amplification, which limits the nonlinear frequency conversion efficiency. Here, by using grating chirped-pulse stretcher and slit, seed light pulses with a pulse duration of 7 ps and a central wavelength of 1030 nm at the repetition rate of 52 MHz were stretched to 32 ps with the spectral width of 1.1 nm. Then the average power was amplified to 190 W by using two air-clad photonic crystal fiber amplifiers (PCFAs). Finally, via a temperature phase-matched LiB3O5 crystal, output power up to 103.1 W was obtained with the beam quality factor 1.17 and the second harmonic conversion efficiency of 54.3%.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20200522 (2021)
  • Dongsheng Liu, Xu Liang, Ying Lin, Yifan Xu, and Xiaodong Fang

    Aiming at the actual demand for long pulse width of 308 nm excimer laser for medical use, a Simulink simulation model was proposed to guide the scheme of extending the laser pulse width, and experimental research was carried out. First, the effectiveness of the simulation model of the excitation circuit of a typical excimer laser discharge was established and verified. Second, the discharge excitation model of a 4-level LC peaking circuit was established based on the principle of pulse forming network, and the design and parameter selection of specific laser structure were carried out. Experiment with a 308 nm excimer laser, an energy storage capacitor of 60 nF and a voltage range of 20-29 kV was completed. By changing the structure and parameters of excitation circuit, the laser pulse width was extended from 30 ns to 60 ns, and when the voltage value of energy storage capacitor was 28 kV, the output energy was up to 407 mJ, the transfer efficiency of laser pulse energy was increased from 1.531% of the typical structure to 1.73%, and the high energy transfer rate under the condition of the long pulse output of discharge excitation 308 nm excimer laser was realized. It verifies the validity and effectiveness of the Simulink simulation model. The guiding significance is to provide the basis for the design and application of the practical long pulse width excimer laser.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210022 (2021)
  • Zichen Wang, and Aimei Zhang

    In order to improve the precision of laser tracking measurement for mega gear, a combined measuring network for mega gear was established by combining laser tracking device and flexible joint coordinate measuring arm. The coordinate transformation relationship between the global coordinate system of laser tracker and the coordinate system of flexible joint coordinate measuring arm was determined by using the frog jump technology to realize the spatial registration of measurement data at different stations. A multi-dimensional measurement method of laser tracker was introduced, which had abandoned the angle measurement module, a multi-dimensional measurement position parameter calibration model of laser tracker was established, redundant data were measured and L-M optimization iteration was carried out in this method in order to improve the global control accuracy of laser tracker. The simulation experiment of combined measurement network was carried out, and the measurement data were analyzed and compared. The average error of combined measurement network was 0.007 mm and the error standard deviation was 0.004 mm. Under the same conditions, the average error of direct measurement method using laser tracker was 0.044 mm. The simulation results show that this method can improve the measuring accuracy obviously and meet the requirements of the measurement of tooth shape of mega gear. It has a good theoretical and engineering application value.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210030 (2021)
  • Lijing Wang, Baiqin Zhao, and Shixuan Yang

    The light quality of the pulsed semiconductor laser directly affects the detection accuracy. Aiming at the miniaturization requirement of laser detection system, a laser driving chip with small area and high integration was designed. The chip integrated the gate driving die and the power field effect transistor die using 3D stacked packaging technology, and added a double-side copper-clad ceramic substrate in the middle to realize the interconnection of the two dies. This packaging form not only improved the heat dissipation capability of the chip, but also enhanced the overcurrent capability. First, the current status of the laser detection transmitter module was introduced in detail, the design ideas and methods of the laser driver chip were introduced, and the specific packaging design process was given. Then, the gate driving circuit and layout were designed, and the gate driving chip was fabricated with a 0.25 μm BCD process. The multi-chip packaging scheme was designed. By setting up a peripheral circuit for testing to make the chip drive the 860 nm laser, the chip can output a narrow pulse with a pulse width of 180 ns, rise and fall times were less than 30 ns, and reached a peak current as high as 15 A when the chip power supply voltage was 12 V, the input level was 3.3 V and the frequency is 10 kHz PWM signal. It can make the laser emit light normally and meet the detection requirement. The chip has an ultra-small area about 5 mm×5 mm, which solves the problem of congestion in the internal space of the detection system caused by the traditional laser drive circuit using multi-chip modules, and provides a new idea for miniaturization.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210034 (2021)
  • Kang Cao, Chenghao Jiang, Jingguo Zhu, Juan Du, Zhi Qiao, and Zhengyu Ye

    In order to improve the performance of the laser Doppler velocimetry system and enhance the adaptability of the system to application scenarios, the characteristics of the two main frequency shift devices of electro-optic and acousto-optic were compared. Starting from the principle of frequency shifting of devices, a simplified method of analyzing frequency transformation relations was proposed. The frequency shift characteristics of the two devices in the laser Doppler velocimetry system was theoretically studied, all-fiber laser velocimetry system link of a lithium niobate electro-optic modulation and acousto-optic frequency shift were bulit. The test frequency characteristics and the theoretical characteristics was compared. A new type of acousto-electric hybrid modulation laser Doppler velocity measurement system was proposed. The results show that the new system has the advantages that the acousto-optic frequency shift speed measurement system can measure the movement direction and speed of the moving target, and accomplish the multi-frequency correction of electro-optic modulation speed measurement system, the relative error of frequency measurement is small, and the dynamic range is large. By studying the frequency characteristics of the two frequency shifting methods, it provides theoretical and experimental support for the design of high-performance laser Doppler velocity measurement systems.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210116 (2021)
  • Xiaoming Li, Longming Wang, and Guoshuai Zhu

    In the "one-point to multiple-points" network laser communication system, in order to reduce the effect of flatness error of mounting surface plane on surface shape accuracy of reflective mirror, make sure the surface shape accuracy of the servo tilt-mirror for the “one-point to multiple-points” network laser communication, the theory analysis of support parameters of integration SiC/Al tilt-mirror was proposed. The effect rule of each parameters on the tilt-mirror surface shape accuracy was analyzed. The support parameters were designed optimally by finite element analysis, and the support point position and the flatness accuracy requirement of the mounting surface plane were defined. The test of surfaces shape accuracy of tilt-mirror using the design parameters after optimation shows that under the premise that the peak and valley (PV) value of the processed surface is better than 53 nm(λ/12), and the root mean square (RMS) value is better than 10 nm(λ/60), with a temperature load of (20±5) ℃, the tilt-mirror is installed, the PV value of the its surface shape accuracy is better than 210 nm(λ/3), and the RMS value is better than 60 nm (λ/10). In addition, the tilt-mirror and the mounting base are made of the same material, which effectively reduces the influence of the temperature change load on the surface shape accuracy. It meets the indicator requirement of servo tilt-mirror surface shape accuracy of the “one-point to multiple-points” network laser communication system.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210143 (2021)
  • Nuerlan Tuerdahong, Lianqing Zhu, Guangwei Chen, Huiyu Li, and Jing Zhu

    Enhancing the sensitivity of the miniaturized spin exchange relaxation free (SERF) atomic magnetometer for weak magnetic detection research is a difficult problem at present. A structure of sensitivity enhanced vapor cell based on Fabry-Perot cavity was proposed to solve this problem. With the principle of Fabry-Perot cavity resonance and theory of light transmission matrix, the amplification factor of optical rotation angle of emitted laser was studied in theoretical analysis and numerical simulation. The results of theoretical analysis and numerical simulation show that as the number of laser transmission round trips in cavity increases, the amplification factor of output rotation angle increases linearly in the initial stage then tends to a maximum value. Ideally, the maximum value is 16 and it is determined by the structural parameter of Fabry-Perot cavity. Besides, the absorption caused by alkali metal atoms spin collision and cavity off-resonance reduce the amplification factor in different ways. Numerical simulation results show that the reduction of amplification factor is close to 50%, while the off-resonance is π/32. This sensitivity enhanced vapor cell is easy to integrate, and provides a new perspective of sensitivity enhanced atomic magnetometer and thoroughly understanding of spin collision in alkali metal vapor cell.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210155 (2021)
  • Zhenzhong Feng, Zhenyuan Yang, Chen Yu, Yang Bai, Zhao Song, Shiyue Xu, and Jianbo Gao

    In order to meet the demand for large-volume data, high real-time and high-reliability of multi-line, high spatial-resolution lidar, an information processing system based on Zynq-7000 was designed. In terms of hardware design, internal resources of Zynq were fully utilized to configure multiple interfaces connecting external simple circuit merely which implement controlling and status monitoring of many peripheral devices. In terms of software design, more flexible AMP mode was adopted, not popular SMP, that each processor, a master and a slave, ran bare-metal program independently, in which a master processor controls time sequencing of data conduct of system and computes alternately with slave processor in ping-pang scheme. Cooperation between processors was optimized and improved. Distance and intensity correction algorithm was proposed and realized further on the basis of high-accuracy combination method of full waveform matching of AD and TDC upon that system, which not only investigate the relationship between correction quantity and distance and intensity, but also study influence of temperature and difference among detectors. In experiments 64-lines lidar has ability of detecting and processing three echoes, distance accuracy of which was better than 1.5 cm within 120 m. Intensity data of lidar expressed target characteristics more objectively and data rate of single echo reached 2 560 K points per second.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210684 (2021)
  • [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210668 (2021)
  • [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210822 (2021)
  • Feng Zhang, Yuanbo Liang, Li Zhao, and Yuan Liang

    Indoor visible light communication (VLC) systems are usually designed based on asymmetric clipped optical orthogonal frequency division multiplexing (ACO-OFDM) and DC biased optical OFDM (DCO-OFDM). These system models usually use CP, channel equalization and carrier multiplexing to solve the problems of channel interference and multi-user multiplexing. But these are at the expense of effectiveness. Non-orthogonal multiple access (NOMA) improves spectrum utilization by sub-carrier multiplexing in power domain, and uses serial interference cancellation (SIC) for multi-user signal processing. It is an effective method to balance communication reliability and effectivity. An indoor VLC system based on NOMA was proposed, and a VLC signal transmission and channel gain model based on NOMA-DCO-OFDM were established. According to channel gain of multi-user, the power allocation of NOMA was carried out to realize the multiplexing in power domain and improve the capacity of system and the communication rate. SIC was used to demodulate the multi-user signals one by one according to the power allocation algorithm to reduce channel interference and improve the reliability of the system. Theoretical analysis and experimental verification show that the communication rate of the system reaches 6.8×107 bit·s-1, the combined rate is not significantly affected by the number of users, and the communication efficiency is significantly improved. For 2 users, when BER is 10-4, user 1 has about 5.2 dB performance improvement, user 2 has about 2.3 dB performance improvement, the communication reliability is also improved.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210101 (2021)
  • Tianxiu Li, Lei Shi, Jiahao Li, and Junhui Wang

    Quantum Key Distribution (QKD) technology now is used in more fields with its good security and confidentiality performance can effectively deal with communication security threats. The application of QKD technology based on aviation flight platform is expected to greatly improve the security level of aviation communication system and provide reliable guarantee for local area secure communication. To analyze airborne application of Measurement Device Independent QKD(MDI-QKD) with asymmetric transmission efficiency, the simulation analysis model combined with the decoy state method was established. The effect of meteorological conditions, flight height on the performance of the system simulation were analyzed. The results show that the application of MDI-QKD protocol in the air mobile platform at the common flight altitude of early-warning aircraft can provide combat communication guarantee under the fine weather with the visibility of about 15 km, but there are communication blind areas and movement restrictions of the flight platform in the long-distance communication. Further experiment indicates the adjustment of signal pulse intensity is an effective method to improve the performance. Above all, the experiment provides theoretical basis and optimization method for the further research and practical application of QKD on flight repeater platform.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210124 (2021)
  • Guanghao Shao, Jiquan Zhai, Xingwei Ye, and Guoqiang Zhang

    Among parameter system of radar, detection distance and target distinguishable ability are important ones, which are related to compression dynamic range(CDR) and noise figure(NF) of receiving link. Nowadays, applications of radio-over-fiber(ROF) in radar receiving link are moved forward. Besides studying on optical link itself, cooperation analysis on both microwave and optical wave should be given. Therefore, microwave pre-amplifier, ROF link and microwave post-amplifier were coupled together. CDR and NF of receiving link based on ROF were discussed universally. For example, if power spectrum density(PSD) noise of ROF was -164 dBm/Hz and optical gain was -20 dB, the CDR1dB and NF of receiving link could be 143 dB·Hz and 4.15 dB with pre-amplifier of 41 dB. In this case, detection distance and target distinguishable ability could both match requirements of system. Moreover, parameters of optical devices were also discussed. For ROF based on external modulated optical links, half wave voltage of modulators could be among 2.0 to 5.8 V to balance performances and costs. Therefore, studies from the aspects of system proof that receiving link based on ROF could meet the requirements of radar functions. Design principles for electronical and optical devices were provided in the meantime.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210251 (2021)
  • Yuanjin Chen, Weijing Chang, Qingfei Liu, Fang Dai, and Lingxue Wang

    1280×1024 EMCCD is a solid-state low light level imaging device with interline transfer structure. It has the ability of all-time imaging and detection from starlight to sunlight environment. It can be widely used in space remote sensing, visual perception and manless driving. However, due to the limitation of device saturation output, when the incident light intensity is too high for EMCCD, blooming takes place, resulting in the reduction of image resolution and affecting the ability of EMCCD to obtain target information. In order to improve the environmental adaptability of EMCCD and avoid the occurrence of blooming, the causes of EMCCD blooming was analyzed, the working principle of vertical antiblooming was introduced, EMCCD pixels with vertical antiblooming structure were designed through theoretical derivation, analysis and numerical simulation, and a 1280×1024 EMCCD device and principle demonstration prototype with vertical antiblooming function were produced. The simulation data and test results show that the vertical antiblooming EMCCD designed in this paper has 500 times antiblooming ability.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210083 (2021)
  • Yang Wang, Ning Wang, Zhiyuan Gu, Lei Zhang, and Yuegang Fu

    Based on the requirements of modern society for high pixels and miniaturization of mobile phone lenses, based on the principle of concentric lenses, a concentric reflective mobile phone lens was designed. Through optical path calculation, the spherical aberration expression of the system was solved, and the initial structure of the system was further obtained. The optical system was designed using optical design software, the lens adopted a curved sensor with a pixel size of 1.25 μm, the F number of the optical system was 1.8, the focal length was 2.7 mm, the maximum full field of view was 100°, and the total system length was 2.7 mm. The results show that at the spatial cut-off frequency of 400 lp/mm, the modulation transfer functions of the 0.7 field of view are all greater than 0.34, and the modulation transfer functions of the full field of view are all greater than 0.23. The radius of the diffuse spot in each field of view is smaller than the Airy disk. In the full field of view, the relative illuminance is higher than 0.64. This design meets the imaging requirements of mobile phone lenses.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210129 (2021)
  • Rui Wang, Xiuqin Su, Yongming Qiao, Tao Lv, Xuan Wang, and Kaidi Wang

    Two-axis fast steering mirror based on flexure hinge support and voice coil motor drive is a strong coupling system with two inputs and two outputs. The coupling between X-axis and Y-axis greatly reduces the positioning accuracy of the fast steering mirror. It is difficult to achieve high precision decoupling control by using traditional PID control algorithm. Based on the centrosymmetric and axisymmetric two-axis fast steering mirror, the coupling sources of the two-axis fast steering mirror—DC coupling component and non-DC coupling component were analyzed theoretically, and the coupling physical model of between X-axis and Y-axis was established. A dual feedforward + dual neural network adaptive decoupling control algorithm was proposed to respectively compensate DC coupling components and non-DC coupling components. Experimental results show that, compared with the traditional PID control algorithm, the coupling degree of the proposed algorithm is reduced from about 5% to less than 1.0‰, which significantly improves the positioning accuracy from about 2.5% to less than 0.5‰.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210194 (2021)
  • Junjie Fan, Fuqiang Li, Weijun Cai, Qinglin Li, Zhandong Zhang, and Shitao Ding

    The focal plane of a space camera will defocus under the launching vibration and shock and complex environmental conditions in space which are changeable. In order to compensate defocusing for focusing mechanism that is long array focal plane with heavy load, a focusing mechanism was designed. This focusing mechanism was driven by two sets of motion mechanism that could provide large driving torque. The two overconstrained lead rails could meet the need of mechanical property. Every mechanism contained a stepper motor, a screw, a encoder, a rolling guide and gear transmission. The finite-element emulation analysis method was used to establish simulation model of focusing mechanism. Through the modal analysis, it verified that this mechanism had a better rigidity and could meet dynamic requirement. Analysis of focusing precision and stability accuracy indicate that the focusing precision of focusing mechanism is 3.8 μm, the stability is less than 5″ and the synchronization precision is 1.1 μm. The design analysis and experimental results show that the focusing mechanism has high focusing precision and high reliability, which can make use of precision adjustment of long focal plane.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210270 (2021)
  • Ruidong Wang, Jun Ma, Chenglong Wang, and Tianzhi Yu

    Compared with the trough concentrator heat collection system, the linear Fresnel concentrator heat collection system has lower optical efficiency, but it has a cost advantage. In order to improve its optical and thermal properties and reduce heat loss, scholars have conducted numerous research. Based on the summary of the optimization design of the main reflector, the secondary reflector and the mirror field of the linear Fresnel concentrator and heat collection system, as well as the thermal performance of the system and other existing research results at home and abroad, the focus was on the shading and blocking, end loss, tracking error, dust accumulation, optical loss caused by the geometric structure of the main mirror field and improvement measures. A comparative analysis of several mainstream secondary reflection receivers shows that CPC-type secondary reflection receiver is the most practical. At the same time, the enhanced heat transfer between the heat absorption tube and the working medium, and the heat loss of the linear Fresnel condenser using CPC were summarized, the existing problems and solutions were analyzed, the future development direction and improvement measures of LFR system were point out.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210452 (2021)
  • Zhuang Liu, Qidong Wang, Haodong Shi, Chao Wang, and Huan Qin

    Orthogonal cascaded liquid crystal polarization grating can realize optical beam large angle-scale deflection, and has broad application prospects in the fields of space laser communication and LiDAR. It need to emit and receive laser at the same time in most application fields, but how to solve the problem of separating emitted light from received light has not been reported. To solve this problem, change of polarization state of outgoing polarization light source after passing through passive liquid crystal polarization grating layer and orthogonal cascade liquid crystal polarization grating was deduced based on the theories of 1/4 wave plate, 1/2 wave plate and liquid crystal deflection grating, the reversibility of the polarization state of the outgoing light and the beam deflection angle was verified. An optical structure which could realize the deflection and separation of transmitted beam and received beam was designed using polarization splitting prism, 1/4 wave plate, 1/2 wave plate and orthogonal cascade liquid crystal polarization grating. A test system was constructed, the test results prove the correctness of the theory and the applicability of the optical structure finally.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210551 (2021)
  • Zhihua Cai, Xiaokun Wang, Haixiang Hu, Xuefeng Zeng, and Jing Wang

    With the development of single-point diamond turning technology (SPDT) and polishing technology, the rapid, efficient and low-cost manufacturing of metal mirrors has been realized. However, the test methods of metal mirrors have obvious shortcomings, especially there is no fast and efficient test method for testing convex aspheric metal mirrors. In order to improve the test efficiency of convex aspheric metal mirrors, a non-null stitching method to test convex aspheric metal mirrors was proposed. Combined with engineering examples, a stitching test experiment was carried out on a convex aspheric metal mirror with a diameter of 120 mm, a radius of curvature of the vertex R of 1121.586 mm, and a conic constant K of -2.38. The residual surface shape obtained by stitching RMS=0.016λ(λ=632.8 nm). Compared with the Luphoscan test results, it is verified that the test accuracy of the non-null stitching test method RMS=0.007λ, which shows this test method can achieve rapid and efficient test of convex aspheric metal mirrors.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210061 (2021)
  • Yonggang Yan, Zhengxing Wu, Zhi Li, and Yuqi Tang

    Ultra-fine positioning stages are the indispensable components in many areas of nanotechnology and advanced material analysis, and are always integrated into analytical devices such as Scanning Probe Microscope (SPM), optical microscope. The mechanical properties of the microscopic measurement system were strongly influenced by the nano-mechanical performance of an ultra-fine positioning stage. A traceable calibration setup for investigating the quasi-static performance of nano-positioning stage was developed, which utilized a differential plane mirror interferometer with double-pass configuration from the National Physical Laboratory (NPL). Based on an NPL-developed FPGA and LabView, the laser interferometric data acquisition (DAQ) and data decoding system with high precision and stable frequency was built up to enable traceable quasi-static calibration of ultra-fine nano positioning stages. Furtherly, the proposed system was used to calibrate and analyze the metrological characteristics of nano-positioning stages. The experimental results have proven that the calibration setup can achieve a noise floor lower than 10 ${\rm{pm/}}\sqrt {{\rm{Hz}}} $ under nearly open-air conditions. The calibrated pico-positioning stage has an excellent nano-mechanical performances, such as the linearity of being lower than 1.2×10-6, the resolution of being up to 40 picometer, good repeatability and stabilization. The results indicate that the proposed method and system can be used to measure the performances of the ultra-fine positioning stages, and furtherly be used for pico-indentation with indentation depths down to a few picometers and the large-scope measurement at the atomic scale.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210070 (2021)
  • Wenyi Chen, Jie Xu, and Hui Yang

    In computer vision, camera calibration as the premise of camera measurement technology, is an essential part. Aiming at the problem that the training accuracy of camera calibration method based on neural network is not high enough, a camera calibration method based on double neural network was proposed. Starting from the imaging model, it was deduced that the camera coordinate ${Z_{\text{c}}}$ was a function of the world coordinate and the pixel coordinate. On the basis of considering ${Z_{\text{c}}}$, the imaging model was simplified into two function relations, and two neural networks were used for calibration, which not only differentiated the task amount of single neural network, but also fully followed the imaging model. The experimental results show that compared with other calibration methods based on neural network, this method improves the accuracy of camera calibration. And the average calibration error is 0.1786 ${\rm{mm}}$ in the calibration range of $400\;{\rm{mm}} \times 300\;{\rm{mm}}$, which verifies the feasibility and effectiveness of proposed method.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210071 (2021)
  • Fang Zhang, Jiaobo Gao, Lanlan Zhang, Jianjun Mi, Shaojun Shou, Anfeng Zhang, Ying Feng, and Rui Hou

    There is many interference information of targets contained in the interference fringes which are obtained by the variable gap Fabry-Perot (F-P) interferometric imaging system. The sinusoidal nature and modulation of the interference fringes directly affect the extraction of interference information of the target. The reflectivity value of the variable gap Fabry-Perot (F-P) interference cavity material is an important performance parameter of the variable gap F-P interferometric imaging system. In order to improve the performance of the variable gap F-P interferometric imaging system, the reflectivity of the variable gap F-P interferometric cavity depends on the sinusoidal nature and the modulation of the interference fringes. In this paper, the mathematical relationship between the sinusoidal nature and modulation of interference fringes and the reflectivity of F-P cavity with variable gap was established respectively and a reasonable objective function was given. When the sinusoidal nature and modulation of the interference fringes were relatively optimal at the same time, the optimal reflectivity of material of the F-P cavity with variable gap was found. The long wave infrared variable gap F-P interference spectral imaging system was built, and the correctness of the above theoretical analysis was verified by measuring the spectral transmittance of polypropylene film.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210099 (2021)
  • Chao Xiang, Daodang Wang, Jinchao Dou, Ming Kong, Lu Liu, and Xinke Xu

    Aiming at the measurement needs of large-aperture optical elements with ultra-large dynamic range, a sub-aperture stitching testing method based on optical deflectometry was proposed. According to the surface feature, the sub-apertures were divided and sequentially measured with the proposed fringe-illumination deflectometric testing system. Based on the slope data measured with actual testing system and ray-tracing result in the system model, the tested surface in each sub-aperture could be reconstructed with high accuracy and be stitched for full-field testing. Compared with the interferometric testing method, the optical deflectometry testing was larger in dynamic range and field of view, which could greatly reduce the number of subapertures required, thus greatly improving the measurement efficiency. Additionally, a weighted-fusion algorithm based on overlapped regions was proposed to obtain the smooth stitching result. To demonstrate the feasibility of the proposed method, both the numerical analysis and experimental verification were carried out. The high accuracy and large dynamic range were validated in the reflective lampshade testing. The result shows that the stitched surface obtained by the proposed method is consistent and smooth, and its surface deviation RMS compared with the full-aperture measurement result is 0.0957 µm, which is smaller than microns. The proposed method is high in measurement accuracy, large in dynamic range and also simple in system configuration, providing an effective and feasible testing method for various optical elements with complex reflective surfaces.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210105 (2021)
  • Jushang Li, Yinze Zhan, and Lidong Zhang

    In order to improve the spectral resolution of the static polarization spectrum imaging system and obtain better target recognition ability, the orthogonal combined Wollaston prism group structure was designed, and the static phase modulation technology was used to complete the polarization spectrum imaging of the target. This technology used a multi-stage prism combination method to expand the range of spatial optical path difference without expanding the size of the original static interference prism, thereby improving the static spectral resolution. The two-dimensional image and the spectrum were separated by the method of phase modulation and image periodic matching. The function relationship between the structure size and the modulation degree on the spectral resolution was analyzed by simulation. The feasibility of the separation of the two-dimensional image and the spectrum were verified by computational simulation. The signal contrast of the 30.0 cm aluminum plate target was tested under two different conditions: sunny and cloudy. The polarization spectrum imaging was used and data extraction were 53.4% and 49.3%, while the mean of test result based on intensity image was 24.4 % and 14.1%. This design can improve the target recognition effect and increase the spectral resolution accuracy.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210339 (2021)
  • Yonghong Xue, Shiwei Fan, Kai Qiao, and Lei Zhang

    With the rapid development of technology and practical deployment of hypersonic weapon, the United States has carried out a new plan of building Tracking Layer of National Defense Space Architecture (NDSA). Firstly, the main design parameters of tracking layer were introduced; Secondly, the analysis model of tracking layer constellation coverage performance, detection capability and tracking performance were established; Finally, the performance of tracking layer was analyzed through simulation and calculation, and the core capabilities such as the minimum satellites number of the whole constellation, detection sensitivity and optimal global target tracking accuracy were deduced. The analysis results have important reference value for the research of data processing algorithm and the design of similar payload and constellation.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210067 (2021)
  • Anjin Liu, Jing Zhang, and Shaoyu Zhao

    The vertical cavity is the core structure of lasers, detectors, filters, sensors and so on. The optical field distribution of the vertical cavity has an important impact on the performance of these devices. The structure of the vertical cavity affects the optical field in the vertical cavity, thus affecting the design, fabrication, and performance of devices based on the vertical cavity. In recent years, many studies have been done on the construction and optical manipulation of vertical cavity, and remarkable progresses have been achieved in fundamental theory and device applications. Firstly, the dispersion characteristics of the conventional top/bottom distributed Bragg reflector vertical cavity, the optical manipulation methods and their applications in lasers and filters were introduced; Then, the dispersion characteristics of one- and two-dimensional high-index-contrast subwavelength grating (HCG) based vertical cavities were presented, and the optical manipulation of HCG-based vertical cavities in novel lasers and monolithic multi-wavelength filter arrays were reviewed; Finally, the article was summarized and the new applications of vertical cavity were prospected.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210425 (2021)
  • Mengyu Wang, Lekang Fan, Lingfeng Wu, Zhizhou Lu, Bo Liu, Zhuang Guo, and Chengfeng Xie

    Kerr optical frequency comb has an equidistantly distributed comb-like spectral structure and has important applications in precision measurement, optical clocks, coherent optical communications, microwave and optical arbitrary wave generation, spectroscopy, and calibration of astronomical spectrometers. Firstly, compared with other optical frequency comb systems, the microresonator optical frequency comb has the advantages of strong integration, small size and good flexibility, which greatly expands the application of optical frequency combs. Secondly, a MgF2 microresonator with a quality factor up to 4.8×107 was prepared by an ultra-precision machining method, and a clean, regular and regularly arranged spectrum was obtained. The free frequency range was 9.73 GHz, which provides conditions for generating low repetition rate optical frequency combs. Finally, according to the experimental results and the Lugiato-Lefever equation, the generation process of the MgF2 microresonator optical frequency comb was analyzed, and the influence of the pump power on the optical frequency comb was studied. The soliton state optical frequency comb was obtained by adjusting the detuning parameters. In addition, the optical field mode of the microresonator was optimized through dispersion control, which creates a condition for generating a soliton optical frequency comb with an ultra-smooth spectrum and improves the performance of the optical frequency comb.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210481 (2021)
  • Chengyu Shen, Zhicheng Gong, Tianhua Mao, Quan Yuan, Yong Li, and Hao Fu

    Micro-nano mechanical resonators are believed to be an ideal platform for developing on-chip signal processing devices, in which various kinds of physical fields can be transduced to mechanical phonons for phonon-based information processing. In such a strategy, control of phonon transferring between different mechanical resonators is essential for phonon-based information processing. By coupling two mechanical resonators for a two-mode mechanical system, although coherent phonon transferring between hybridized mechanical modes has been achieved recently, direct control over the effective coupling between disparate mechanical resonators is still desirable. Therefore, coherent control of phonons through Landau-Zenner-Stückelberg (LZS) interference was developed in an optomechanical system in this paper. The hybridization between two mechanical resonators was mediated using the effect of optical trapping, and a parametric driving field was applied through modulating the optical trap so that the system transvered the avoided-crossing point periodically to realize the LZS interference of phonons. The studies demonstrate that coherent phonon transferring between two disparate mechanical resonators can be achieved through the LZS interference when the on-resonance condition is satisfied. The authors' research provides an efficient scheme for high-efficient transferring of phonon-based information in real space.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210521 (2021)
  • Qiang Luo, Fang Bo, Yongfa Kong, Guoquan Zhang, and Jingjun Xu

    Lithium niobate on insulator (LNOI) was regarded as a competitive integrated optical platform due to the excellent optical performance of lithium niobate crystal and integration characteristics of thin-film devices. In addition to the research on transmission and control devices, such as waveguides and modulators, significant progress has been made in LNOI lasers recently. The research status of the rapidly developing LNOI microcavity laser was reviewed in this paper. Firstly, the main technical schemes of rare-earth ion doping of bulk lithium niobate and LNOI, as well as the recent exploration on the preparation of rare-earth ion doped LNOI micro-/nano- optical devices, were introduced; Secondly, the research progresses on Erbium-doped lithium niobate on insulator (Er-LNOI) microdisk and microring cavity lasers were summarized; Then, the working mechanism of several common methods to realize single-mode laser in microcavity laser system were described. The research progresses on Er-LNOI single-mode lasers utilizing "Vernier effect" and mode-loss modulation were introduced in the following; Finally, based on the reported research results of LNOI lasers, the limitations of the current research and the future research directions were discussed.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210546 (2021)
  • Zhuoya Zhu, Shuai Zhang, Wenna Du, Qing Zhang, and Xinfeng Liu

    When the interaction between excitons and cavity photons is stronger than the decay of excitons and cavity photons, a strong coupling occurs between exciton energy level and cavity mode, thereby generating the quasi-particles called exciton-polaritons. The small effective mass and strong nonlinearity of exciton-polariton make it great potential in the applications of slow light and low-power-consumption light emission devices. However, weak exciton binding energy of traditional III-V inorganic semiconductor materials and weak nonlinearity of organic semiconductor materials limit their application of exciton-polaritons at room temperature. In contrast, halide perovskites have a series of excellent photoelectric properties such as high absorption coefficient, long diffusion length, high defect tolerance, and low rates of nonradiative recombination. Furthermore, with large exciton binding energy and oscillator strength, halide perovskites become an ideal material for studying strong interaction between light and matter. The research progress on exciton-polaritons based on the strong coupling between halide perovskite and Fabry-Pérot (F-P) microcavities was introduced from two aspects: the structure kinds of halide perovskites and the type of F-P microcavities. Firstly, the research background of polaritons and the basic photoelectric properties of halide perovskites were reviewed. Secondly, the respective characteristics of three-dimensional perovskites and two-dimensional layered perovskites and related research on strong coupling with F-P microcavities were introduced. Afterwards, the regulation and application of self-organized and non-self-organized F-P microcavities to perovskite exciton-polaritons were discussed. Finally, the challenges and future research directions of halide perovskite exciton-polaritons were summarized and prospected.

    Nov. 25, 2021
  • Vol. 50 Issue 11 20210619 (2021)
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