Dispersive prismとは 意味・読み方・使い方

In optics, a dispersive prism is a type of optical prism, normally having 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 (the colors of the rainbow). This dispersion occurs because the angle of refraction is dependent on the refractive index of a certain material which in turn is slightly dependent on the wavelength of light that is travelling through it. This means that different wavelengths of light will travel at different speeds, and so the light will disperse into the colours of the visible spectrum, with longer wavelengths (red, yellow) being refracted less than shorter wavelengths (violet, blue). 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.