QS Study

Plane Transmission Grating

A diffraction grating is an optical component with a usual model. The form of the light diffracted by a grating depends on the construction of the elements. It is an optical component whose effect is alike to a prism: it splits white light into its component colors.

A plane transmission grating is a transparent plate or surface made of glass or of similar material on which a very large number of equidistant parallel lines very near to each other are scratched by a sharp diamond point. Here each line acts as an opaque line and the space between two lines acts as a thin slit. Each centimeter of this grating contains 5000 to 6000 lines. It can be easily constructed by drawing a huge number of intimately spaced lines on a plane transparent plate-like glass with a pointed diamond point. The lines on the plate are opaque to light and the spaces between these lines are transparent.

For ordinary use, another type of transmission grating is used in the laboratories. Replicas of the original grating are prepared on a celluloid film.

On the original grating surface, a thin layer of collodion solution is poured and the solution is allowed to harden. Then the film of collodion is removed from the grating surface and then fixed between two glass plates. This serves as a plane transmission grating. It is called replica grating.