PREPARATION OF PARTIAL GRATING

PURPOSE:To obtain the partial grating easily by forming a negative type resist film onto a substrate, coating a grating forming prearranged section with a mask, exposing an exposed resist film, developing the film and removing the resist film of a developing section, and etching the substrate while using the remaining resist film as a mask. CONSTITUTION:The negative type resist film 2 is formed onto the SiO2 substrate 1, and the mask is aligned and the resist film 3 except the grating forming prearranged section is exposed and cured. The resist film 3 is exposed by using an interference exposure method by laser beams or an electron beam exposure method, and developed and gratings 5 are formed only in sections 4 not cured. The substrate is etched while using the remaining gratings 5 as masks, and the gratings 6 are formed to the surface of the substrate 1. Accordingly, the gratings are obtained only in desired sections.