Abstract:Aiming at the requirements of lightweight and stiffness improvement of silicon carbide (SiC) plane mirror in the two-dimensional pointing mechanism of space camera, an innovative design scheme based on semi-closed backplate structure was proposed. By constructing a semi-closed topological configuration on the back and replacing the traditional open structure with it, the stiffness was improved by combining the control of the process hole size. The finite element model of the pointing mirror was established, and three design schemes were compared. The simulation results show that, under the premise of ensuring the surface shape accuracy index, the mass of scheme 2 was reduced from 12.8 kg to 10.7 kg (a decrease of 16.4%), the first-order natural frequency was increased from 730 Hz to 1528 Hz (an increase of 109%), and the stiffness-to-mass ratio was increased by 1.5 times. The performance index was significantly better than that of the traditional open structure (scheme 1) and the large aperture scheme (scheme 3). The optimized pointing mirror passed the sinusoidal vibration test, and the root mean square (RMS) value of the surface shape accuracy was doubled from 0.073λ to 0.036λ (λ=632.8 nm). The semi-closed backplane design proposed in this study breaks through the stiffness limitations of traditional lightweight structures and provides a new approach for the design of other space mirrors.

Abstract:Aiming at the recognition difficulties of infrared small target detection caused by few pixels, weak texture and no color, an infrared small target detection algorithm for aerial unmanned aerial vehicle (UAV) is proposed. Based on multi-frame infrared sequences, the ResNet-50 network is used to extract deep features frame by frame, and the multi-scale deformable attention mechanism and cubic interpolation are combined to enhance the detail representation of small targets; the frame decoder and target decoder are designed to generate the spatiotemporal mask of the target instance through the video-level query vector. The Hungarian algorithm is used to optimize the classification, mask and similarity losses during training; the high-confidence query mask is fused during inference, and the inter-frame difference method is used to suppress static noise. On the DSAT dataset, the accuracy of the algorithm in this paper reaches 0.6356 and the F-score is 0.6475, and the performance is significantly improved. Through multi-scale feature fusion and temporal modeling, the algorithm effectively solves the problems of missed detection and false alarm of infrared small target detection algorithm, and provides a high-precision solution for UAV detection.

Abstract:In order to prepare high-quality mercury cadmium telluride (HgCdTe) materials with high reliability and controllable doping concentration, the properties of HgCdTe materials after As doping need to be studied. The As doping technology of silicon-based HgCdTe by molecular beam epitaxy (MBE) is reported. Using As cracking source as As doping source, high-quality HgCdTe materials are prepared, in which the As doping concentration can reach 8×10¹⁸ cm^-3. The study found that As doping is very sensitive to material growth parameters such as growth temperature, As beam current, and material composition. By improving the growth temperature control and substrate heating method, the uniform distribution of As concentration in the horizontal and vertical directions of the material can be achieved. As activation annealing is carried out by a two-step annealing method. When the As concentration is lower than 3×10¹⁷ cm^-3, the activation rate tends to 100%; with the increase of As doping concentration, the activation rate shows a downward trend.

Abstract:Taking the deep mesa etching of medium- and long-wave two-color InAs/GaSb type-II superlattice infrared detector as the research background, the relationship between the photolithographic solid-film process and the quality of the deep mesa sidewall is analyzed. The influence of different solid-film temperatures on the graphic transfer effect of the mesa pattern and the quality of the mesa sidewall forming is studied, and the best solid-film process is obtained through optimization. The superlattice medium- and long-wave two-color photosensitive chip with smooth sidewalls is interconnected with the readout circuit and packaged into the dewar; it is cooled to 77 K by liquid nitrogen, and then the component test is carried out. The experimental results show that the medium- and long-wave two-color superlattice material uses AZ4620 photoresist as a pattern mask, and after a gradient temperature increase to 140 °C for solid-film, a mesa junction device with smooth sidewalls is obtained by dry etching. The module test results show that the smooth sidewall can effectively reduce the noise equivalent temperature difference (NETD), blind pixel rate and non-uniformity of the module.

Abstract:Indium bumps (i.e. indium balls) used in flip-chip interconnection technology are a material used to achieve electrical connection between chips and substrates in semiconductor packaging. If the indium columns are left for too long after wet shrinkage, oxides will form on the surface of the indium balls. Indium oxides can be quickly identified using a metallographic microscope. The influence of the presence of indium oxides on the pressure and conductivity of flip-chip interconnection is analyzed and discussed, and wet and dry methods are proposed to remove oxides. The parameters of the removal method are quantitatively studied, and the removal effect is tested and analyzed, making the research conclusions more comprehensive and complete. The results show that the detectors after flip-chip interconnection of the circuit with oxides removed by this method have relatively stable performance, laying a good foundation for the preparation of high-quality and high-reliability detectors.

Abstract:The splicing of multiple videos on the display can not only monitor and view from a large viewing angle and various angles, but also solve the problems of messy display of multiple viewing angles in a single camera video and the inability to display the whole view due to target occlusion. A display with multi-channel infrared video splicing based on field programmable gate array (FPGA) is designed. The design of the display uses JFM7K325T-900 FPGA as the processor, and is equipped with two SCB15H1G160AF-15HI 16-bit synchronous dynamic random-access memory (SDRAM) as the image cache module. It supports serial digital interface (SDI) and high-definition multimedia interface (HDMI), and provides three high-speed digital video interfaces called flat panel display links (FPD-LINK). The three infrared video interfaces process three infrared video images with a resolution of 1280×1024 into three images with a resolution of 640×720 through FPGA to fill the display with a resolution of 1920×720. The results show that the display can display infrared images of different scenes in real time and complete multi-channel infrared video splicing.