Fabrication of UV transmission blazed gratings by holography-ion beam etching

As an essential component of the slitless spectrometer, the UV transmission blazed grating has the capability of high dispersion and high resolution. In this paper, a method for fabricating UV transmission blazed gratings by holography-ion beam etching is proposed. Holographic interference lithography is used to generate photoresist grating masks. The ion beam vertical etching transfers the photoresist mask pattern to the substrate to form a SiO2 grating mask. When the ion beam incident direction is at a certain angle to the normal direction of the substrate, the SiO2 mask is used to block the inclined ion beam, so that different parts of the mask bottom are bombarded by the ion beam with different fluxes, forming a blazing facet. When the mask is etched completely, the blazed grating is formed. Based on the idea of the line motion algorithm, the article establishes the geometric model of blazed grating etching, which provides the parameter guidance for precise control of the groove structure. Combined with the theoretical model, a UV transmission blazed grating with a line density of 333 lines/mm and a blazing angle of 13.2 degrees is successfully fabricated.