Research on Laser Warning Receiver Based Coherent Detecting Principle and Ratio of Signal to Noise Analysis of its Optical Subsystem

摘要

Real time and reliable measurement of the wavelength and arriving direction of tunable pulsed laser in harsh environment is a challenge issue in optoelectronic countermeasure. In order to discriminate the hostile laser beam from background light such as sunlight, glare of gunfire and lightning, coherent detection technology has been used in novel laser warning receiver. We have developed a grating-based laser warning receiver which can be used to detect the wavelength and arriving direction of pulsed tunable laser in the spectral range from 500-1100nm from harsh background. At first, using Fourier Fransform Principle and angular Spectrunm theory, The paper theoretically analyzed the SNR of the optical subsystem caused by sunlight, and the simulation results have been applied in the design of the optical subsystem, then, a laser warning receiver prototype based on grating has been designed, which consists of a transmission amplitude grating, a plant-convex cylinder lens, a linear CCD with 50 MHz driving frequency made by ATMEL Company, a High speed DSP TMS320VC5509 and a liquid Crystal Screen. The three months'trial in open air shows that the LWR has the following technical characteristics: measurement wavelength range is from 500 to 1100 nm, wavelength resolution is less than or equal to 10 nm, the Field of View is 22.5 in latitude or longitude, the incident angle resolution is about 1°, the responding time to laser threat is less than 0.1 s, the detecting sensitivity is less than 10 mW/cm{sup}2.