PRODUCTION METHOD FOR COMPOSITE TYPE DIFFRACTIVE OPTICAL ELEMENT, AND COMPOSITE TYPE DIFFRACTIVE OPTICAL ELEMENT

摘要

A composite type diffractive optical element having a resin layer laminated on a transparent substrate is molded. Then, cooling of an unmolded surface of the transparent substrate is started using a cooling spray nozzle so as to provide a temperature gradient in one direction from an outer periphery toward a center, and a cooling range is expanded in the one direction to cool the transparent substrate. With this, mold releasing is performed in one direction from the outer periphery portion to an opposite outer periphery portion across the center of the diffraction gratings to release the resin layer from a diffraction grating mold.