Development And Experimental Study Of Radiation Effect Test System For CCD Image Sensor

Charge coupled device(CCD)is a kind of photoelectric conversion image sensor with MOS structure,which has the functions of imaging,data processing,communication and so on.Because of its low noise,high sensitivity,stable operation and other advantages,it is the most important device of spacecraft imaging system,and is widely used in remote sensing,telemetry and space science detection.When the CCD operations in orbit,the damage induced by charged particles in the space environment leads to its performance degradation or even functional failure,which affects the performance and life of the space system on orbit.Therefore,it is necessary to study and analyze the performance degradation and damage mechanism of CCD in space environment.In this paper,based on the commercial CCD device TCD1703C of Toshiba company,a test system for radiation effect is developed,and the ⁶⁰Co gamma ray irradiation experiment is carried out with this system.The experimental rules of CCD sensitive parameter degradation are obtained,and the radiation damage mechanism of CCD is analyzed in depth.This paper introduces the hardware circuit design and software design of the test system in detail.The hardware circuit design of the test system includes system power module,FPGA main control module,CCD drive circuit module,AD conversion module and wireless transmission module.The software design of the test system includes CCD timing drive design,AD converter timing drive design and data cache FIFO design.The test system uses wireless transmission technology to achieve the long-distance communication with the computer,which makes the system more flexible and convenient in special application scenarios.The system is tested by radiation experiments,and the results show that the system is stable and can meet the needs of CCD radiation experiments.The experiments of ⁶⁰Co gamma ray irradiation were carried out by using the test system.The variation of CCD dark signal,saturation output and other radiation sensitive parameters with accumulated total dose and bias conditions was obtained.The experimental results show that with the increase of cumulative radiation dose,the dark signal performance of CCD degrades and the non-uniformity of dark signal increases.The increase of dark signal is closely related to the bias condition,and the degradation of dark signal performance of CCD with bias is more obvious.Ionizing radiation damage will lead to the decrease of saturation output and charge transfer efficiency.The saturation output is also closely related to the bias condition,and the device with bias decreases more significantly with the increase of radiation dose.In the process of annealing at room temperature,the dark signal is recovered to a certain extent with annealing time,but the saturation output remains unchanged.The experimental results show that the annealing effect at room temperature has a positive effect on the recovery of dark signal performance,but has little effect on the saturation output.The experimental results verify that test system can provide technical support for CCD irradiation experimental research.