Study On Autogated Power Supply Applied In Generation In Image Intensifier

The low-light-level(LLL) image intensifier(I~2) which can detect two dimensio -nal weak light picture is mainly used to observe target in the battlefield during the night time. Because light level of field of view changes much in the battlefield , I~2 must have a wide dynamic range for all-weather battle. The dynamic range and lifetime of Generation Ⅱ I~2 are not big enough. The target of this thesis is to overcome these disadvantages by an autogated power supply.Firstly, the work principle and the function parameters of three main parts of Generation ⅡI~2 include a photocathode, a microchannel plate (MCP) and a screen are introduced. And the relation between fatigue and input luminance is analyzed in theory.Because the automatic brightness control(ABC) function is provided by the power supply, the work principle of the traditional direct current high voltage power supply is analyzed. And the reason that dynamic range and lifetime of Generation ⅡI~2 are not big lies in the realization of ABC function by adjusting work voltage.The paper introduces the principle and characteristicses of the autogated power supply, analyzes the superiority, feasibility and the advertent problem of autogated power supply applied in I~2 ,and puts forward the design parameters. At the same time, the electric circuit design based on FPGA(fieId programmable gate array),including an amplifier, an A/D converter, a digital pulse width modulator, VMOS switch circuit and so on, making use of the EDA software Multisim2001 to simulate and the experiment result are introduced. Finally, the disadvantages of present design are analyzed and some improvement suggestions are put forward.