Abstract:The observation field of view of space camera in geosynchronous orbit is seriously affected by stray light, so it needs to be quantitatively analyzed. Aiming at the visible channel of the camera, the earth-reflected stray light is studied. The equivalent surface-source integration method is used to calculate the signal-to-noise ratio when observing the 6.5-magnitude star in the visible channel, and the calculation result is compared with the laboratory and on-orbit test data (the average error is less than 15%). The results show that the accuracy of the simulation calculation is high.

Abstract:The nBn infrared detector can effectively suppress the generation-recombination current, thereby increasing the operating temperature of the detector. InAsSb/AlAsSb materials are preferred for nBn infrared detectors due to the advantages that the fabrication process can be transplanted from mature III/V processes and there are perfectly lattice-matched substrates. The research status, working principle and recent achievements of InAsSb/AlAsSb nBn infrared detector are briefly introduced. Through the growth test, good material surface quality, crystal quality, and optical properties are achieved. The related results show that when preparing the device, the doping concentration of the barrier layer in the nBn structure should not be lower than 8×1016cm-3, otherwise it will not help to reduce the dark current of the nBn device.

Abstract:Based on a brief introduction to the basic principles and equipment involved in picosecond laser dicing, the characteristics of some materials often involved in the packaging of infrared focal plane array modules and their action mechanisms to the picosecond laser beams are reviewed. By optimizing the laser parameter settings, the dicing efficiency is improved and the dicing quality is guaranteed; by improving the clamping apparatus, metal layer damage is avoided and the operation convenience is improved.

Abstract:Combined with the optical performance design of infrared detectors, the principle of absorbing and suppressing stray radiation using cold shield blackening layer technology is introduced. Based on the same cold shield structure, three different surface blackening processes are compared, and the physical performance parameters such as the surface absorptivity of the cold shield blackened layer are tested and analyzed. Through the performance test of the infrared detector, the actual influence of different cold shield blackening processes on the performance of the infrared detector is analyzed. The results show that the blackening process of 2# and 3# cold shield can achieve better consistency of surface absorptivity in 2-14 μm band. And in the 8-11 μm band, they have good absorption and suppression of the stray radiation of the infrared detector.

Abstract:Two dark-current test methods for or the mercury cadmium telluride(HgCdTe)infrared focal plane detector are studied. Reducing the dark current is directly related to the signal-to-noise ratio of the detector. The dark current of the developed HgCdTe photovoltaic detector under working conditions is tested and analyzed. By comparing multiple test results, it is found that the operating temperature and process have different degrees of influence on the dark current. This study provides a theoretical basis for improving the process, detector performance and screening efficiency in the future.

Abstract:Wire sawing technology has been widely used in the field of semiconductor crystal cutting. The traditional internal cutting technology is introduced, and the current classification and research level of the emerging wire saw cutting technology are summarized. The working principles and research progress of the two major categories of free abrasive wire saw cutting and consolidated abrasive wire saw cutting are explained. Free-abrasive wire saw cutting is a widely used technology to replace inner circular cutting, while solid-abrasive wire saw cutting is an important improvement for high cutting efficiency requirements. A review of cutting technology for crystal wire saws will help researchers understand cutting-edge research progress and grasp the development direction of crystal wire saw cutting.

Abstract:Using infrared polarization information(degree of polarization, polarization angle)to image a target can better suppress the background noise of the image and improve the signal-to-noise ratio. In addition, the polarization information generally contains richer edge contour information than the light intensity information. Therefore, an algorithm is proposed to fuse the infrared radiation intensity image and polarization image. This method first performs Laplacian pyramid decomposition on each image participating in the fusion to obtain a decomposed image of each layer; then uses different fusion methods for image fusion for each decomposed image to obtain a fused image of each layer.Image reconstruction is performed on the fused image of each layer to get the final fusion result. The effect of multiple image fusion shows that this method can increase the amount of information in the image, which is beneficial to scene perception and target recognition.

Abstract:Aiming at the problems of low contrast and unclear scene details in infrared and visible image fusion, an infrared and visible image fusion method based on total variation is proposed. In this method, the difference between the fusion image after each iteration and the visible and infrared images is used as the regular and fidelity terms of the total variational model. At the same time, a non-incremental diffusion function about infrared images is introduced to guide the diffusion and suppress the smoothness of the edge information of the infrared images, so that the image fusion problem can be transformed into an image denoising problem, and finally it is transformed into a functional problem of finding extreme values. The experimental results verify the effectiveness of the method from visual quality and objective evaluation.