In optics, a diffraction grating is an optical component with a surface covered by a regular pattern of parallel lines, typically separated by a distance comparable to the wavelength of light. Light rays that pass through such a surface are bent as a result of diffraction, related to the wave properties of light. This diffraction angle depends on the wavelength of the light. In its simplest form, a diffraction grating could be a photographic slide with a fine pattern of black lines. However, for practical applications, most gratings have grooves or rulings on their surface rather than dark lines. Such gratings can be either transparent or reflective. Because of their ability of splitting light into different wavelengths (dispersion), gratings are commonly used in monochromators and spectrometers.
For a given grating, light with a larger wavelength generally has a larger diffraction angle. More precisely, a single wavelength can simultaneously have multiple discrete diffraction angles, called diffraction orders.
The principles of difraction gratings were discovered by James Gregory (astronomer and mathematician), about a year after Newton's Prism experiments, initially with artefacts such as bird feathers.The first man-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws. This was similar to notable German physicist Joseph von Fraunhofer's wire diffraction grating in 1821.
1 Theory of operation
2 Gratings as dispersive elements
3 Fabrication
4 Examples
