光栅衍射型超广角激光告警系统的灵敏度分析

Analysis of detective sensitivity for super wide-angle laser warning system based on grating diffraction

研制了光栅衍射型超广角激光告警样机，推导了系统探测灵敏度的估算公式，用1064nm脉冲激光在半视场角0°～78°范围内测试了样机的最小可探测能量密度。结果表明，半视场角0°-42°范围内，入射激光能量密度保持1．8nJ／cm2基本不变的情况下，告警系统I级成像光斑的灰度值约由20逐渐减小为7；48—78°范围内，告警系统的最小可探测能量密度约由2nJ／cm2逐渐增大为7nJ／cm2；分析表明，随激光入射角度增大，告警系统像差增大导致成像光斑面积变大是引起告警系统最小可探测能量密度变大的主要原因。

A model machine of super wide angle laser warning system based on grating diffraction was developed, and the sensitivity estimate-formula of the system was derived, then the minimum detectable energy density of the machine was tested by using 1064nm pulse laser in the half field angle range 0° -78°. Results show that the grey value of imaging light spot in this warning system decreases from 20 to 7 when the incident laser energy intensity remains 1.8 nJ/ cm2 in the angle scope of 0° -42°, and the minimum detectable energy density increases from 2nJ/cm2 to 7nJ/cm2 with the incident angle from 48° to 78° . With the incident angle increasing,the optical aberration of the system increases,it causes the imaging spot to be bigger. That is the main reason for the increasing of the minimum detectable energy density.