Time Distribution of Reflected Light Signals from Partially Coherent Light Passing Through Complex Optical Systems with Multiple Apertures

Abstract

Laser active detection technology scans and detects large target equipped with optoelectronic equipment by transmitting laser beam, converts the received reflected light signal into electrical signal, and obtains target information through various signal processing methods to achieve the goal of target detection. The laser beam output from the high power laser usually has multi-mode structure and partial coherence, and the optical reconnaissance equipment with complex optical structure is an equivalent system with multiple hard edge apertures. In the simulation of the coherent beams transmission through the multi aperture complex optical system, large matrix calculations are required in the spatial optical field computation, which consumes a lot of computation time. Furthermore, the size of the optical receiving lens is far less than the spot size after a long distance transmission, which results in the loss of optical information. To solve the problems, in this article, taking the Gauss Schell model (GSM) beam as a partially coherent light model, based on the Complex Gauss decomposition method for the hard edge diaphragm and ABCD optical transmission matrix, the recursive formula of the time series of the intensity distribution of the coherent GSM beams interference fringe field transmission through a multi aperture complex optical system is derived, and the influences of the spatial coherence of the GSM beam. The effects of the spatial coherence of GSM beams, the initial distance between coherent beams and the equivalent aperture size of complex optical systems on the time distribution of transmitted light intensity are analyzed. According to the results, the influence of the spatial coherence of the GSM beam on the spatial coherence of the beam itself is more obviously than that on the formation of two coherent GSM beam interference field. The interference fringe field spatial distribution and the aperture size are the main factors affecting the transmission of light time distribution. The conclusions obtained in this paper have important reference value for the application of partially coherent optical transmission through complex optical systems, and also provide a new idea for the target echo signal processing method of laser active detection.