A holographic grating is a diffraction grating manufactured using a photolithographic technique that utilizes a holographic interference pattern. Two intersecting laser beams produce equally spaced interference fringes that are projected onto a photoresist material on the grating substrate. The photoresist dissolves in proportion to the intensity of the fringes resulting in a holographic grating that has a sinusoidal profile. The holographic grating is then coated with a reflective coating.
Because a holographic diffraction grating has no periodic errors or imperfections, it exhibits significantly lower stray light compared to a ruled grating and no ghosting effects (See Ruled Grating vs Holographic Grating for further information).
A holographic grating can be blazed to produce a blazed grating that has increased efficiency over a defined spectral region.