Attenuation of 0.532 μm laser beam through raindrops

Rainfall can bring serious attenuation to the laser signals, so it has some influence on the laser proximity fuze applied in the rain. The attenuation of laser beam propagating in the rain has been researched in the infrared range, but the attenuation of visible light laser in the rain has not been reported. Therefore, based on the Fraunhofer diffraction and geometric optics theory, an attenuation model for 0.532 μm laser beam propagating through the raindrops was established. Then the transmittance of several raindrops was theoretically calculated and validated by experiments, and the error was less than 2%. The investigations indicate that absorptivity of the raindrop for 0.532 μm laser beam is 1.32×10^-9 and can be ignored, so only the raindrop scattering is considered in the laser transmission and influenced by the diffraction and geometric scattering synchronously. The transmittance of near infrared laser is lower than that of 0.532 μm laser due to the raindrop absorption. The attenuation model of 0.532 μm laser provides a theoretical basis for the green laser applied in the proximity fuze operating in the rain.