CCD真空低温光电快速测试系统的设计与验证OA

A spaceborne scientific CCD(Charge-Coupled Device)needs a well-adapted peripheral circuit to achieve its best performance.In the design of peripheral imaging circuits,several parameters—such as series resistors,offset voltages,the overlap of driving clocks,etc.—must be optimized according to the feedback of actual tests.Some tests must be conducted under low-temperature conditions to match the en-vironment where the CCD is to be finally installed.Such low-temperature vacuum equipment previously used was designed for entire payloads,making it too bulky for individual CCD devices and front-end cir-cuits.Due to this bulky size,it took extra time and cost a huge amount of liquid nitrogen.Thus,a com-pact,cryocooler-based Dewar was designed in this paper.First,a system composed of an oil-free vacuum unit,a pulse tube cryocooler,and a precise temperature control unit was built.Then,the performance of the system was verified through vacuum pumping dynamics and cold-transfer experiments.Next,with the test system,the circuit parameters were modified and optimized according to the feedback of the experi-ments,which were rapidly repeated several times by taking advantage of the"quick-operation"feature of the test system.Finally,utilizing the photon transfer curve(PTC)method,comparative experiments were conducted on the CCD275 at both room temperature(298 K)and the on-orbit operating temperature(248 K)to evaluate the effectiveness of different parameters in achieving full-well readout.The system achieves an ultimate vacuum of better than 5.0×10-5 Pa and sustains a stable testing environment of 215 K under thermal load,offering rapid evacuation,low cost,convenient installation,and a dedicated design for CCD circuit tests.The tests and measurements on six CCD275 chips show that the effective full-well capacities are in the range of 800 000 to 900 000 electrons per pixel at 248 K with a readout frequency of 2.5 MHz.This system significantly enhances the efficiency of CCD testing and circuit modifications.The test results meet the application requirements for the signal-to-noise ratio and dynamic range.In conclu-sion,this paper discusses the design and implementation of the test system,providing a convenient and versatile testing and debugging solution for scientific-grade CCDs.