Effect of thickness non-uniformity of large-area grating metal film on grating diffraction wavefront

Abstract

Abstract As the grating area increases, the non-uniformity of the metal film thickness becomes one of the main factors affecting both the grating surface error and the wavefront of the grating diffraction order. We study the theoretical model of the relationship between the metal film thickness non-uniformity and the grating diffraction wavefront error, analyze the effects of the relevant factors on the thickness of the metal films, and determine the values of these factors using theoretical and experimental methods. We also perform a ruling experiment to verify that the wavefront quality of the grating increases with improvement in the film thickness uniformity.