Diffraction grating and Optical device

Diffraction grating noun - Optical device consisting of a surface with many parallel grooves in it; disperses a beam of light (or other electromagnetic radiation) into its wavelengths to produce its spectrum.

Optical device and diffraction grating are semantically related. In some cases you can use "Optical device" instead a noun phrase "Diffraction grating".

Optical device noun - A device for producing or controlling light.

Diffraction grating and optical device are semantically related. Sometimes you can replace phrase "Diffraction grating" with "Optical device", this phrases are similar.