Precise Blaze Angle Adjustment of Echelle Grating by Self-Shadowing Rotating Mask

Abstract

Angular precision of 0.1° for the blaze angle of echelle gratings is an important technical requirement for spectral instruments with echelle gratings. This paper proposes a precise adjustment method for the blaze angle of echelle gratings that are etched or deposited by self-shadowing rotating mask. The blaze angle will decrease or increase when the grating is rotated in beams for etching or deposition, respectively. The blaze angle can be controlled by adjusting the etching or deposition conditions. For the echelle grating with nominal blaze angle of 63.0° and groove density of 52.7 g/mm, the blaze angle was decreased by 0.12° with a maximum etching depth of 19 nm on the blaze facet. Additionally, the blaze angle adjustment precision will be better than 0.02° if the maximum etch depth on the blaze facet is less than 3 nm.