Design Of Image Sensor Refrigeration Control System For Telescope Test System

The CMOS image sensor,which is the core component of the detection instrument,is affected by the dark current during imaging,and generates noise interference to the detection target signal.Especially for telescopes that detect dark targets in space,the presence of dark current may make the detection effect worse,and even the target cannot be detected.it is necessary to cool the image sensor,reduce the dark current,and improve the image quality of the image sensor.Aiming at the demand of image sensor for cooling,this paper designs a cooling control system for image sensor.The system uses STM32F407 as the digital control core chip,uses PT100 temperature sensor to collect the temperature signal of CMOS image sensor,filters the high frequency component in the temperature sensor signal through the filter circuit,and use a high-precision ADS1247 chip integrated with a programmable constant current source,amplifying circuit and A/D conversion circuit to conditioning and conversion of temperature signals.The drive circuit uses the PWM control principle to control the magnitude and direction of the current through the thermoelectric cooler,and the control signal sent by the STM32F407 is amplified by the LM5105 chip to control the H-bridge.A sliding mode controller based on exponential approach law is designed according to the nonlinear characteristics of the system,and the experiment is completed on the test bench,which proves that the designed sliding mode controller has good performance.The experimental results show that the sliding mode controller has good performance,and the system can maintain stability in the required temperature range of-20°C to-30°C,and the steady-state error reaches the requirement of ±0.1°C,which meets the system design index requirements.