Noise equivalent temperature difference (NETD) is a key indicator for evaluating the sensitivity of infrared detectors. By changing the readout circuit structure and improving the charge processing capability of the readout circuit, the NETD value of the detector is increased from 10 mK to below 1 mK. When the noise is less than 1 gray level, the NETD value obtained by the existing test method is low, resulting in an overestimation of the recognition distance when the whole machine is used, which is inconsistent with the actual results. The optimization method proposed in this article makes the test results more consistent with the system application indicators. After analysis, it is believed that the detector used is more suitable for low-speed targets or relatively static scenes; compared with conventional detectors, the recognition distance of this detector is more affected by the same optical temperature change. Users are advised to pay attention to the impact of optical temperature stability.

Even-order aspheric surfaces are usually used to improve system performance when designing infrared systems. The optimization function of the design software can quickly find the best aspheric surfaces, but these aspheric surfaces are likely to have oscillating surface patterns. In order to eliminate the irregular aspheric surfaces in the infrared imaging lens and reduce the narcissus phenomenon of the system, the evaluation parameters of the narcissus phenomenon are first analyzed from the definition perspective. Combined with the narcissus light trace diagram, it is determined that the narcissus evaluation parameters are still suitable for the narcissus control of the aspheric surfaces. From the perspective of the sagittal height, the monotonicity of the sagittal height value from the center to the edge of the aspheric lens and the consistency of the sign are controlled to eliminate the irregular aspheric surface. A medium-wave infrared imaging lens is designed, and irregular aspheric surfaces appear in its initial design structure. The irregular aspheric surface is controlled by the method of controlling the sagittal height value and the narcissus suppression scheme. The optimized infrared imaging system has no irregular aspheric surface, and the narcissus energy returned to the detector after reflection from each surface of the lens covers the entire detector image surface, indicating that this optimization scheme is suitable for infrared systems with irregular aspheric surfaces and is more intuitive.

The CdTe/ZnS double-layer passivation process was used to passivate the surface of the long-wave HgCdTe substrate and optimize the process, and different process conditions were used to grow the backside anti-reflection film. The film layers of the diode devices prepared under various process conditions were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and I-V curves, and the effect of the density of the CdTe/ZnS film layer deposited under different process conditions on the device performance was studied. The results show that the CdTe/ZnS passivation film layer with higher density is uniform and has a better surface state; the backside anti-reflection film layer with higher density has stronger adhesion and fewer surface defects, and the prepared LW640-15 detector has higher performance.

In high-level vibration application scenarios, the cantilever beam structure of the infrared detector-dewar assembly is easily damaged. A non-contact helical spring support ring structure is designed. Between the dewar shell and the cold finger, the dewar heat leakage increased by the traditional strengthening scheme is greatly reduced through a non-contact method, and the vibration energy is converted into elastic potential energy, thereby reducing the stress impact of high-level vibration on the cold head. After simulation analysis and optimization with Ansys software, the maximum deformation of the platinum-iridium wire is 1.7 mm, which is 57.5% lower than the conventional structure; the maximum stress decreases by 52% to 307 MPa. Experimental results show that the average heat leakage after optimization increased by only 1%, while having significantly improved vibration resistance. The assemblies with conventional structures would experience platinum-iridium wire breakage after enduring 15 grms durable random vibration, while the optimized assemblies can withstand 15 grms durable random vibration and 17.6 grms short-term high-level random vibration. The optimized assemblies keep the detector focal plane temperature stable during 17.6 grms random vibration without affecting their normal operation.

To meet the application requirements of multi-channel fine spectrometry of infrared detectors, pixel-level filters need to be accurately integrated on the cold head of infrared detector assembly, and the assembly accuracy of the filters in the X, Y and Z directions needs to be controlled within 10 m to reduce the stray light interference between different channels. The pixel-level filter is designed based on a 320×256@30 m mid-wave infrared detector. Four adjacent pixels on the detector are grouped together, and each pixel has its own absorption spectrum on the corresponding region of the pixel-level filter. By comparing and analyzing the spectral absorption curves of the four pixels when the adhesive and the metal filter bracket are respectively used as the supporting structure of the pixel-level filter, it is found that the Z-direction assembly spacing of the former can be as low as 2-10 m, and the stray light absorption outside the cutoff band can be reduced by 25%-50% compared with the latter. The results show that the assembly process using adhesive as the micro-support structure of the filter can effectively solve the stray light interference problem of pixel-level filters.

ZnS thin films were prepared on silicon substrates by magnetron sputtering technology, and the effect of sputtering power on the deposition rate, surface roughness and surface morphology of ZnS thin films was investigated. The surface morphology, microstructure and optical properties of the films were characterized by step profiler, atomic force microscope (AFM), scanning electron microscope (SEM), ellipsometer, etc. The results show that the deposition rate of ZnS thin films is related to the sputtering power, and increases linearly with the increase of sputtering power; the surface roughness of ZnS thin films is related to the sputtering power and shows a trend of increasing first and then decreasing with the increase of sputtering power. In terms of microstructure, the grain size of the film also shows a trend of increasing first and then decreasing. With the increase of sputtering power, the refractive index of the ZnS film layer first decreases and then increases. Therefore, the sputtering power plays an important role in the growth of the film layer.