Research On Low Temperature Coupling Of Large Scale Infrared Detector And Single Point Cold Source

With the development of China space technology,infrared remote sensing equipment develops toward high sensitivity and high resolution.Two important performance indicators of infrared remote sensing equipment are the field of view and resolution.The field of view can increase the observation range of the instrument,and the resolution can improve the image quality of the instrument.In the development of high-resolution large-field optical system,in order to overcome the contradiction between the field of view and resolution,one solution is the use of high resolution efficiency,ultra-large scale infrared focal plane detector assembly.Ultra-long line of 30000 pixels and large area array 4K × 4K detector assembly has become the next generation of remote sensing equipment.With the wavelength to the long wave expansion and detection of increased sensitivity,infrared detectors must be in the deep low temperature.As the mechanical refrigeration has the advantages of compact structure,small volume,light weight,large cooling capacity,short cooling time and large controllable cooling temperature,most of the detectors are mechanically cooled in the application at present.The cold source is mostly on a single point of the refrigerator.Cooling the detector module on a single point makes other parts of the high temperature.In order to ensure the consistency of the detector performance,the detector temperature uniformity of the maximum temperature difference keeps less than 2K.In addition,the movement parts of the Stirling refrigerator expander caused vibration.In order to isolate vibration,there must be a flexible thermal link between the detector and the cold finger.Large-scale infrared detector and single-point cold source coupling technology is the core technology of large-scale infrared detector assembly engineering application.The purpose of this paper is to study the cooling mechanism of infrared detectors and single-point cold sources,and to realize the method of homogenizing the temperature uniformity of ultra-large cold platform.So the infrared detector assembly have higher reliability in harsh space environment.In this paper,a method of obtaining the thermal load and radiant heat of the whole component based on the critical point temperature is proposed for the 8K pixels long line infrared detector assembly.The finite element simulation of ANSYS is used to simulate the 8K pixels long line infrared detector module of type ? and ? models.The simulated thermal load and radiant heat are calculated by the above method.For the type?8K pixels long line infrared detector components,this paper analyzes the influence of the cold screen radiation,the material of the cold screen,the cold-screen installation surface contact resistance,the size of the cold to the entire component of the thermal load and radiant heat.14 temperature measuring diodes are arranged on the key points of the 8K pixels long line infrared detector assembly.The results are in agreement with the simulation results.In this paper,the influence of the flexible thermal link,the radiation of the cold screen and the solid conduction of the support on the temperature uniformity of the cold platform are analyzed by ANSYS finite element simulation of the type ? 8K pixels long line infrared detector assembly.The above conditions were verified by arranging 8 temperature measurement points on the cold platform of type ? 8K pixels long line infrared detector,and the results were basically consistent with the simulation results.A low temperature strain gauge was used to set up a device of testing the heat output of a strain gauge at a low temperature.Using the device described above,a method of testing the stress of a detector chip in a dewar assembly is proposed.Through the measurement,this paper measures heat output of stainless steel,oxygen-free copper,monocrystalline silicon specimen in low temperature.Taking the 2K × 512 detector assembly as the model,the strain of the detector chip at low temperature is obtained,and the stress is calculated by this strain.Finally,the ultimate strain of strain gauges and the strain calculated by strain in the liquid nitrogen temperature(77K)are obtained.It is proved that the stress of the detector chip in the 2K × 512 detector module is in the normal working state.