Glossary
- 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
- Diffraction angle: angle of a diffracted light ray with the normal to the diffracting surface
- Wavelength ( of a light wave ): distance between two consecutive identical states of the electric ( or magnetic ) field
- Frequency: reverse value of the period
- Critical interaction length ( acousto optic ): for a monochromatic light wave propagating perpendicularly to the acoustic wave, distance covered for running through half of an acoustic wavelength in the transverse plane ( plane perpendicular to the light wave propagation ) because of the diffraction - defines an interaction length far below which an acousto optic material may diffract in Raman Nath regime
- Acousto optic effect: diffraction of light in a material in which propagates an acoustic wave generating periodic variations in refractive index