Multi - Point Temperature Detection And Control System For EMCCD Camera

EMCCD was developed as a new kind of weak optical signal detector at the beginning of the century, and it has a broad application prospect in the field of science and military imaging. In some special applications, in order to reduce the noise of EMCCD chip and improve the signal-to-noise ratio, it’s need to make the temperature reach to-100℃,so the liquid nitrogen cooling technology was introduced. Liquid nitrogen refrigeration dewar was applied on refrigeration astronomical CCD camera in 1976. EMCCD chips and peripheral circuit must be put in the liquid nitrogen refrigeration dewar during light detection.This paper is combined with the actual needs of the National Natural Science Foundation Project"Counting imaging technology that is based on a two-dimensional photon EMCCD for astronomy" (10978013).That is to monitor the temperature of the test points in the dewar system and to control the working temperature of the EMCCD chip.This paper presents two kinds of design and implementation techniques:The first is the temperature measurement and control system which is based on MCU,it is two independent systems with the EMCCD camera image acquisition and control system;the second is the temperature measurement and control system which is based on FPGA,it shares the FPGA and the transmission channel with the image system.Temperature detection and control circuit of the two programs are the same.Several PT 1000s as the temperature sensing devices are used in the temperature measurement circuit.The PT 1000s can make the different points of temperature signal into resistance signal.Then the resistance signal through a data selector which has minimal access resistance.Then the signal through a resistance/voltage conversion circuit and the resistance signal is converted into voltage signal.For a voltage signal of the temperature, the A/D converter circuit can convert it into digital signal which can be processed by the processor.The core component of the A/D converter circuit is AD7705.In the MCU program,the model of the MCU is STC89C52RC and the data transmission between PC and processor is RS-232 serial communication;in the FPGA program,the processor is NIOS II which is embedded in the Cyclone 3 FPGA and the data transmission between PC and processor is USB3.0.Control function, receive and storage temperature data function of PC in the two programs are designed by the Dialog in the MFC framework.AND development environment are VC6.0 and VS2010.Experiments show that this design can be achieved on EMCCD chip temperature control and measure the multi-point temperature in the dewar. And this design can provide data support for thermal analysis of the EMCCD camera dewar.