triangular prism (optics)

In optics, a triangular prism is a type of optical prism with the shape of a geometrical triangular prism. It is the most widely-known type of optical prism, although perhaps not the most common in actual use. Triangular prisms are used to disperse light, that is to break light up into its spectral components. This dispersion occurs because the angle of refraction is dependent on the refractive index, which in turn is dependent on the wavelength. This effect can also be used to measure the refractive index of the prism's material with high accuracy. In such a measurement, the prism is placed on the central rotary platform of an optical spectrometer with the incident light beam adjusted such that the refracted beam is at minimum deviation. The refractive index can then be computed using the apex angle and the angle of minimum deviation.
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