Statistical spatial properties of a light field on a target plane

Abstract

Studying the light field characteristics of a target plane is critical in controlling the laser-plasma instability (LPI), which is necessary to increase laser energy utilization and compression symmetry in high-power laser facilities. In this study, a statistical method is used to analyze the transmission light characteristics of a target plane for single and multiple beams. We reconstructed the light transmission model on the target plane and analyzed the relationships between the focal spot width and incidence angle, and speckle width and incidence angle using the autocorrelation function. In addition, the relationship between the interference pattern and incident beams is obtained by deriving the beam superposition theory. The results show that the speckle and focal spot widths are stretched in the direction in which the incident plane projects. The direction of the interference structure generated by multiple-laser beams is perpendicular to the line joining of the sub-beams, and the period is related to both wavelength and incidence angle. Experimental results are consistent with the theoretical analysis. The influence of incident beam number on the focal spot uniformity is also studied. The results are of great significance for regulating the sub-beam incidence direction, understanding light properties to further improve focal spot uniformity and suppress the LPI.