The main failure causes of the integral Stirling refrigerator are the contamination of the regenerator, the wear of the moving friction pair, the failure of the bearing, the failure of the drive control circuit and the leakage of the gas working medium seal. The leakage of the gas working medium seal is the most important factor affecting refrigerator reliability. The main factors affecting the sealing performance of refrigerators are sealing surface machining quality, sealing material and sealing structure. In this paper, the sealing structures of two typical refrigerators are selected as the research object, and the finite element models of the sealing structures of the refrigerators are established. The simulation results show that the stress distribution of the center symmetric seal structure is more uniform than that of the axisymmetric structure, which is beneficial to the improvement of the sealing performance of the refrigerator. The results also provide a reference for the improvement of reliability in the subsequent production process of the refrigerator and the design of the new refrigerator.

The low temperature deformation and micro-vibration displacement of the coupling interface of large-scale infrared focal plane (such as large array and long line array) are comprehensively evaluated to ensure that the chip deformation, stress and pixel displacement at low temperature can meet the application requirements after the coupling of focal plane detector. The point sampling of the infrared focal plane of a certain model at 80 K operating temperature is carried out by the conjugated microscopic system to obtain a multi-point three-dimensional coordinate system, and then the plane fitting of the coordinate system is carried out to obtain the low-temperature deformation and micro-vibration displacement of the focal plane. The low temperature deformation of the infrared focal plane is 18 m by simulation and 19 m by measurement. The deduced value of micro-vibration displacement is 0.7 m, and the measured result is 0.9 m. Both measured values meet the index requirements. The image of this model of infrared camera is clear in orbit and rich in layers, which indicates that the method is more realistic and effective to evaluate the low temperature deformation and micro-vibration displacement of the coupled interface, and can provide reliable and effective guarantee for the subsequent model projects.

After using distributed infrared sensors to detect the same target, the image of the multi-sensor target can be fused at pixel level to improve the signal-to-noise ratio (SNR), so as to improve the detection ability of the system. Starting with the detection range of a single infrared sensor, the range evaluation model of distributed multi-infrared system collaborative detection is described, and the noise equivalent temperature difference (NETD) formula is deduced including integral time. The Little Hudson detection range equation is expressed by NETD. The multi-sensor image fusion method is used to improve the SNR of the image, which is equivalent to extending the integration time and suppressing noise to improve NETD. Combined with the relation formula of the false alarm probability and detection probability, a reference for setting SNR in the detection range equation of multi-infrared sensors is provided. NETD and SNR are considered in the detection range evaluation model of distributed multi-infrared systems. Theoretical calculation shows that multi-sensor cooperative detection can effectively improve the detection range of the system, which provides important theoretical support for the comprehensive demonstration of distributed infrared systems.

In order to meet the demand for InSb materials in the development of mid-wave infrared detectors, InSb synthesis and zone-melting equipment is taken as the research object, and the thermal field of InSb synthesis and zone-melting is studied in this paper. The structure of the combined thermal field is studied for the two-step process, and the thermal field is numerically simulated by the finite element simulation analysis method. The temperature distribution and law suitable for the process are obtained. After the process experiment, the melting zone of 3--10 cm appears in the ingot, and the N-type InSb ingot with carrier concentration and mobility meeting the requirements is obtained. The combined and three-stage thermal field structure effectively improves the efficiency of material preparation and reduces the manufacturing cost. The results show that the temperature field distribution of synthesis and zone melting equipment meets the design requirements. The simulation results provide a theoretical basis and effective means for the optimization and improvement of such equipment, and provide a material preparation basis for the development of infrared detectors.

With the development of infrared detector technology, the demand for high-quality mercury cadmium telluride epitaxial materials is gradually increasing, which also puts forward higher requirements for the quality of cadmium zinc telluride substrates. The morphology and composition of a large-sized point like defect with a platform around it on the surface of a liquid-phase epitaxial cadmium telluride mercury film are characterized. The morphology of this type of defect is similar to a crater with a central depression (referred to as a “crater” shape), and its composition does not show significant deviation from the normal area of the tellurium cadmium mercury epitaxial film. Research has found that during the liquid-phase epitaxy process, approximately triangular or circular defects appear on the substrate surface before the growth solution of mercury cadmium telluride comes into contact with the cadmium zinc telluride substrate, and there are pore like morphologies below the defects. A “crater” shaped defect appears on the surface of the epitaxially grown mercury cadmium telluride film above the defect. The source of this defect is located to provide support for controlling the occurrence of such defects in the future.

The infrared spectrum characteristic of high temperature gas is an effective way to judge the composition and concentration of gas. Aiming at the problems of complex infrared radiation characteristics and high modeling difficulty of high-temperature gas, a feature extraction algorithm based on interval partial least squares (iPLS) and kernel principal component analysis (KPCA) is studied. Firstly, the characteristic spectral bands with the best prediction ability are determined by pre-screening with iPLS to avoid the loss of useful absorption peak information in the process of single subinterval modeling. Secondly, KPCA is used to reduce the data dimension, retain the key features with high contribution rate, and reduce the complexity of the component prediction model. The simulation results show that after feature extraction by iPLS-KPCA method, the complexity of the prediction model is greatly reduced, and the prediction ability is significantly improved.

In this paper, a rapid detection method for estazolam based on terahertz spectroscopy technology is developed to solve the problems of cumbersome pre-processing, sample loss, long time and high cost in the detection process by HPLC. Firstly, DFT is used to predict the molecular vibration mode of estazolam in 0.9-20.0 THz frequency band, and a qualitative analysis method is established. Secondly, by analyzing the correlation between the content of estazolam and the characteristic peak of terahertz, a quantitative analysis model with a high fitting degree is established. Then, the terahertz spectrum analysis of 22 estazolam products from different manufacturers is performed, and the SVR algorithm is combined to achieve an accurate quantification with MAE of 1.12% compared with the HPLC method. The method has the advantages of simple operation, fast analysis speed, low cost and non-destructive testing, which provides a new analytical strategy for the quality control of special drugs, and has the potential to be extended to the quality evaluation of other anesthetic drugs.