Research On Cooling Technique For EMCCD Carmera

MCCD is one of the most sensitivity image sensors in the world, which meet great needs in astronomical observation, biomedicine, basic physics research and other fields. Cooling is the only way to reduce EMCCD thermal dark signal, meanwhile it improves EMCCD Multiplication Gain. So cooling is the irreplaceable security for high sensitivity EMCCD. Nowadays many foreign camera companies have mastered this technology, and valued it as their core competitive advantage. In our country, there are very few researches on this technique, which further shows the urgency and importance of this research.The relationship between EMCCD’s performance and temperature is analyzed before developing specific cooling technique to get theoretical critical cooling temperature of three EMCCD chips, i.e. CCD60, CCD97 and CCD 201. Then this paper studys on EMCCD cooling technology from the following three aspects: thermal insulation design, Thermoelectric Cooler design and optimization, and temperature measurement.The optimal task of heat insulation design is bringing up a feasible program to realize high efficient heat insulation between EMCCD chip and the environment. At first, EMCCD camera heat transfer path is analyzed, and how to curb remnant gas heat transfer is found to be the key of thermal insulation design. Then widely used vacuum heat insulation principle, effect and difficulties in applying to this research are illustrated in detail. Confronting with these obstacles, this paper proposes two new thermal insulation programs based on related theories from Heat Transfer and hydromechanics: thermal insulation through depressing natural convection by controlling the thickness of Krypton and thermal insulation through depressing natural convection by controlling the pressure of Krypton. Principle, heat insulation effect and invalid environment of these two options are analyzed and illustrated specifically, with the help of theoretical analysis, value calculation and simulation, etc. CCD60 is designed based on the first program,and an experimental system is designed based on the second program.The aim of TEC design and optimization is to optimize TEC structure and operating electric current in cooling system, thus to reach lower cooling temperature and higher cooling efficiency. Based on thremaoelectric cooling principles, two methods to analyze TEC are proposed: “Finite Analysis Method”and “Experience Parameter Method”. Precision and application of the two methods are analyzed. Then “Experience Parameter Method” is used to analyze TEC’s best performance parameters and outer influential elements. At last, numerical simulation is done on experiment system cooling effect and TEC work current under different cooling temperatures is optimized by combining Experience Parameter Method and heat network of these experimental systems.This paper did deep research on contact resistance, conduct resistance and heatsink thermal resistance, because TEC’s performance is closely related to thermal resistance. Heat resistance optimization is designed and a theoretical optimized heat resistance value is calculated, in which heatsink thermal resistance accounts for the biggest proportion. Then air cooling and water cooling are considered, on which a new heat sink integrating air cooling and water cooling is designed. Then theoretical performance analysis is done on the new heatsink.This paper also does research on cooling system temperature measurement. After figuring out system temperature demand and enormous research, PT1000 platinum resistance of P1K0.232.4SW.B.010 from IST Corp. is chosen as the temperature sensor of cooling system. Temperature measurement precision of this sensor is also tested.Experiments are done on these two systems. The following contents are included: influence of Krypton pressure to cooling temperature, cooling temperature time response characteristics,its actual working state and lowest cooling temperature. It is shown that experiment results are consistent with expectations. At last parameters of CCD60 camera, designed by ourselves are presented, comparing with Andor DV 860 parameters. Some test results of CCD60 are shown in appendix.