Objective The core component of space remote sensing camera imaging is the detector, which is generally an image sensor and is fixed to the mechanical parts. The traditional fixed method of the detector is to use the pressing plate and other parts for mechanical fixing, which is easy to cause assembly stress, which will affect the shape of the detector's sensitive surface and affect the imaging quality. However, for light detectors of small size, a bonding method can be designed to control the thickness of the adhesive layer to reduce the bonding force and ensure the structural strength after bonding.

Methods The accuracy change of the detector by different bonding methods was analyzed by simulation combined with environmental test. Firstly, according to the working environment of the detector assembly, the appropriate adhesive is selected, the specific model is GHJ-01 optical epoxy adhesive and GD414 silicone rubber. Due to the different coefficient of thermal expansion of the bonded objects, the stress will be generated when the temperature changes. In order to reduce the stress, the thickness of the adhesive layer is determined to be 0.2 mm through the non-thermal bonding equation combined with the actual engineering calculation, and the bonding area is calculated to ensure the bonding strength. Six bonding schemes were proposed according to the parameters of the adhesive layer. The finite element simulation analysis was carried out on the detector components in the six schemes. The deformation of the key elements of the detector photosensitive surface was calculated and output, and several bonding schemes with small change of the detector photosensitive surface shape were obtained under the condition of temperature rise. After random vibration and high and low temperature cycle tests, optical splicing instrument and coordinate measuring instrument were used to detect the changes in detector splicing accuracy (including detector component straightness and detector flatness), and the optimal bonding scheme was obtained by comparing the test results.

Results and Discussions The results of finite element simulation and environmental test are compared and analyzed. Firstly, by comparing the results of the finite element simulation analysis of six schemes, three bonding schemes are obtained under the condition of temperature rise, the shape change of the sensor's photosensitive surface is less than 0.001 2 mm. They are respectively GHJ-01 optical epoxy adhesive bonding bottom surface, GD414 silicone rubber bonding detector bottom and side surface, and GD414 silicone rubber bonding detector bottom and side with GHJ-01 optical epoxy adhesive top dispensing. The test results after vibration test and high and low temperature test show that GD414 silicone rubber is used to bond the bottom and side of the detector, and GHJ-01 optical epoxy adhesive top dispensing scheme can ensure that the surface shape accuracy of the detector assembly is better than 0.000 7 mm and the linear accuracy is better than 0.001 mm under the condition of 200 ℃ temperature rise and mechanical vibration.

Conclusions Through the simulation and environmental verification of different schemes, the conclusion is drawn by analyzing the accuracy change of the detector’s photosensitive surface. For small and light detectors, GD414 silicone rubber is used to bond the bottom and side of the detector, and GHJ-01 optical epoxy glue at the top can reduce the thermal stress of the adhesive layer, maintain the sensor's photosensitive surface shape, and meet the bonding structural strength of the light detector and meet the requirements of detector assembly splicing accuracy.