What is holographic grating?
Holographic gratings are formed by an interference fringe field of two laser beams whose standing wave pattern is exposed to a polished substrate coated with photoresist. Processing of the exposed medium results in a pattern of straight lines with a sinusoidal cross section.

Concave holographic grating is a reflection grating made by double light interference method, it has the characteristics of collimation, focusing and spectroscopy, with low stray light, simple structure and other advantages, is the ideal spectroscopic element for small monochromator, mainly used in semi-automatic biochemical analysis of liquid chromatography and other instruments.