holographic grating

A grating made by using a holographic process where a photoresist is placed on an optical surface such as a glass blank. A series of interference fringes corresponding to the grooves of the desired grating model are recorded on this photosensitive layer by projecting a hologram of light and dark lines. Subsequent chemical treatments are used to erode either the exposed or unexposed photoresist material (there are different types of treatments such as positive and negative photoresist processes) on the surface to produce a grooved diffraction grating of specified groove
shapes and lines per millimeter.