Influence factors and laws of laser active illumination uniformity

Abstract

Active illumination with narrow spectrum laser based on ladderlike phase modulator (LPM), is an effective method to improve the illumination uniformity. Laser spectrum style, lens number of LPM and lens thickness error of LPM are three significant factors impacting the illumination uniformity in engineering. The laws of the three factors with scintillation indexes are analyzed through numerical simulation. The results indicate that the laser spectrum style is not an important factor, and the spatial scintillation indexes of Uniformity, Gauss, Lorenz style narrow spectrum laser is 0.27, 0.28, 0.28 respectively. The scintillation indexes are decreased gradually with the lens number of LPM. The spatial scintillation index is increased from 0.266 to 0.271, when the lens thickness error of LPM is -0.6 millimeter. Therefore, several opinions are proposed when this method is used in the engineering project, few attentions should be imparted to laser spectrum style, lens number of LPM should be optimized considering the laser spectrum width and scintillation index synchronously, and the minus lens thickness error of LPM should be controlled attentively.