Abstract:Hyperspectral imaging technology originated from remote sensing, has the unique advantage of spectral integration. It is increasingly widely used in agriculture and forestry, geology and mining, anti-counterfeiting and environmental protection. As the most common and basic function of hyperspectral technology, target classification plays a vital role in the application of hyperspectral fields. In this paper, the development status of hyperspectral target classification technology is reviewed, the structural characteristics of hyperspectral data are analyzed, the general process of hyperspectral target classification is summarized, and the mainstream methods and basic principles of data reading, image preprocessing and target classification are described in detail. Combined with the typical cases in recent years, the process of hyperspectral target classification is analyzed, and the development trend is analyzed and prospected.

Abstract:The stability of the performance of indium antimonide wafers during storage and use is one of the important factors affecting the performance of the prepared detectors. In order to investigate the performance changes of indium antimonide wafers under long-time storage, high-temperature accelerated storage test was carried out on indium antimonide wafers, and several important performance parameters such as geometrical parameters, surface roughness, electrical parameters and dislocation defects were tracked and detected in the process of the test. The results show that under the conditions of high-temperature accelerated test, except for the slight change of wafer shape, other properties basically do not change, and the wafers can be stored for a long time.

Abstract:Based on the theoretical analysis of the cantilever beam structure of the detector-dewar assembly , the optimal design method of the mechanical weak structure of the dewar assembly is proposed, and Ansys software is used to simulate the structure of the dewar assembly before and after optimization. The results show that the modal first order fundamental frequency of dewar assemblies is significantly increased, which is 130% higher than that of parallel supported assemblies and 317% higher than that of conventional unsupported assemblies. Through the test verification, it is found that the vibration resistance of dewar assemblies has also been greatly improved, and 15g durable random vibration, 17.6g short-term mass random vibration as well as 2000g mechanical impact can be resisted.

Abstract:The surface passivation of mercury cadmium telluride (MCT) materials is one of the key processes in the preparation of infrared detectors.High-performance MCT devices require stable and reproducible passivation surfaces and interfaces that meet the device performance requirements. Therefore, it is of great significance to explore MCT surface passivation technology. Molecular beam epitaxy (MBE) in-situ passivation and magnetron sputtering passivation techniques of MCT were studied. The results show that the compactness of the in-situ passivation film by MBE is better, the defect holes on the surface of the passivation layer are smaller, the lattice matching between the passivation layer and the MCT is better, and the current-voltage (I-V) characteristics of the device streamer are better than normal passivation by magnetron sputtering.

Abstract:With the wide application of infrared imaging equipment in military and civilian fields, how to judge the technical status of infrared imaging equipment quickly and consistently as well as analyze and solve problems becomes more and more urgent. In this paper, a portable infrared target simulator based on zoom dual-band is proposed. Through the design of high-precision blackbody (accuracy: better than 0.01℃ during －10℃ and 260℃), card insertion and pull-out target, and 3× continuous zoom dual-band projection structure, the detection requirements of infrared imaging equipment are met. Compared with other simulators, the simulator takes into account two bands and improves the application range of the equipment. In addition, the replaceable target and zoom projection are conducive to taking into account the simulation detection requirements of different infrared imaging equipment at different distances. According to the test results, the expected goal is achieved, the practical simulation test demand is realized, and the problem of high cost is solved.

Abstract:CO₂ is one of the main greenhouse gases, which plays a great role in global warming. Since industrialization, the concentration of CO₂ has increased substantially worldwide. In order to achieve the target of carbon reduction, it is urgent to monitor the concentration of CO₂ in the atmosphere and analyze its spatial and temporal distribution characteristics. With the launch of greenhouse gas observation satellites, carbon satellites can be used to observe and analyze atmospheric CO₂ concentration on a large scale. Using GOSAT-2 satellite data and Kriging interpolation technique, the spatial and temporal variation of CO₂ column concentration (XCO₂) over China''s land area from June 2020 to May 2021 is analyzed. The results show that the nationwide average XCO₂ has increased from 413.86 ppm in 2020 to 419.59 ppm in 2021（an increase of 5.73 ppm）. The lowest and highest values of XCO₂ appear in winter and spring, respectively. The further analysis shows that XCO₂ is spatially inconsistent, with higher concentration in the densely populated southeast region and lower concentration in the sparsely populated northwest region. In addition, XCO₂ in large cities and their surrounding areas are generally higher than that in other areas, indicating that human factors cause XCO₂ in urban areas to increase too quickly. The analysis results can provide important basic data and reference for the study of carbon sources and sinks.