Glossary
- Diffraction: divergent nature of a wave due to its limited size
- Angle of incidence: angle of a light ray incident on a surface with the normal to the surface
- Grating: optical device made of periodically spaced out diffractive elements
- Diffraction angle: angle of a diffracted light ray with the normal to the diffracting surface
- Pitch ( grating ): distance between adjacent diffractive elements of a grating corresponding to the period of the diffracting pattern
- Wavelength ( of a light wave ): distance between two consecutive identical states of the electric ( or magnetic ) field
- Diffraction order: for a diffraction grating or an acousto optic crystal and a given monochromatic plane light wave, defines the difference between the optical paths expressed in wavelength unit and traveled by light rays diffracted by two consecutive diffractive elements ; also defines the directions along which the diffracted wave may propagate
- Refraction index: for a transparent medium, ratio between the light speed in the air and the light speed in the medium ; for a reflective surface in the air or vacuum, the refraction index is « - 1 »