Diffraction effect of entrance pupil by irradiating visible light array CCD with pulsed laser

The regular circular fringes could be observed when the visible array CCD was irradiated by 532 nm pulsed laser from a distance of 31.5 m. Their generating conditions and mechanism have been investigated by changing the incident angle, the attenuation factor, repetition frequency and distance. The experimental results show that in the premise that the incident angle of laser is smaller or a little larger than the half angle of view 6.8, the regular circular fringes can be observed as long as the power density can reach 10-3 W/cm2 at the pupil of optical system. It was proved that the regular circular fringes were caused by the diffraction effect of the pupil of optical system, based on the simulation of energy distribution on the detectors surface.