Research On Calibration Method Of Electronic Multiplication Gain In

Due to the unique charge multiplication mechanism of the electron multiplying charge coupled device (EMCCD),make it especially suitable for detecting and imaging extremely weak target. But the electron multiplication gain will change in the operation of the EMCCD,, affecting the imaging quality of EMCCD imaging system. In order to improve the performance of EMCCD imaging system, the EMCCD imaging system with the function of gain calibration is developed. In this thesis, through analyzing and researching the multiplication process of TI Company’s EMCCD, a method is proposed to determine the electron multiplying EMCCD gain, and the gain correction circuit is designed.In this thesis, firstly, we propose a method to determine the gain of EMCCD, through analyzing the gain model of EMCCD proposed by Robbins, calculate parameters c in the model of the two devices by using the device data (TC285SPD and TC253SPD) provided by the TI company respectively, and establish the model of key parameters c of the two device by multiple regression analysis, so as to determine the expression of EMCCD of gain correction model. The model can accurately calculate the average gain of the electronic signal through multi-stage cascade EMCCD multiplier register in different temperature under the condition that the EMCCD has experienced a certain aging time, so that it can be used to gain adjustment and correction of EMCCD imaging system. In the second, according to the overall structural design and requirements of the gain correction analog circuits of implement the EMCCD gain correction model, the operational principle of each unit circuit was described respectively, the key analog devices are selected to design schematic of gain correction of analog circuit. Pspice simulation of the system principle diagram of gain correction of analog circuit was implemented, simulation calculation results and gain correction model theory results are almost consistent; for digital circuit of gain correction, we combine the VHDL programming and the IP core of Altera to design the log, exponential converter based on CORDIC algorithm, using IP core to realize the multiplication, division, anti-equal function. The accurate operation of the digital circuit unit is realized through functional simulation, and after comparing the simulation results of the gain correction of digital circuits with the theoretical calculation results of the gain correction model by connecting each circuit unit, we can know that they are almost the same. Finally, the results show that EMCCD gain correction of digital circuit is more suitable for EMCCD imaging system gain calibration after comparing system performance of the EMCCD gain calibration of analog circuit with EMCCD gain correction of digital circuit from the following aspects, such as the processing speed, the simulation output results of the data accuracy, the consumption of resources and degree of difficulty of the circuit realization.