Influence of beam shape on piston and tilt error in coherent combined laser array

Abstract

An analysis of beam combining quality and the influence of beam profile on tilt and piston error tolerances is presented. We define beam combining performance metrics in terms of powers contained within a specific radius. It is shown that the selection of this radius has a significant effect on the obtained tolerance values. We have taken the tolerance limit as a decrease in intensity of 20%, for piston and tilt error. In addition, for the tilt error, as tolerance limit, we have taken a pointing error equal to the diffraction limit. Our analysis demonstrates that the beam combining performance metric based on the diffraction-limited radius functions best for describing the impact of aberrations on the coherent combined laser array optical system. Our results lead to two important conclusions. First, the tilt error has a greater impact on the degradation of beam quality. Second, a Gaussian beam has greater tolerance for both errors than a top-hat beam. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.