diffraction grating

A very large reflecting diffraction grating An incandescent light bulb viewed through a diffractive effects filter. Diffraction grating

In optics, a diffraction grating is a grating with a periodic structure of appropriate scale so as to diffract light, or another type of electromagnetic radiation, into several beams traveling in different directions (i.e., different diffraction angles) known as diffracted orders. The emerging coloration is a form of structural coloration. The directions or diffraction angles of these beams depend on the wave (light) incident angle to the diffraction grating, the spacing or periodic distance between adjacent diffracting elements (e.g., parallel slits for a transmission grating) on the grating, and the wavelength of the incident light. Because the grating acts as a dispersive element, diffraction gratings are commonly used in monochromators and spectrometers, but other applications are also possible such as optical encoders for high-precision motion control and wavefront measurement.