The page begins with more commentary on the design and functioning of spectrometers, both those that split emitted radiation from high energy excitation and those that measure reflectances.
Dispersion is accomplished by prisms or fine-line gratings.
Several other hyperspectral instruments are mentioned. The simplest device is an optical glass prism whose cross-section is a triangle. At this glass surface, the rays with different wavelengths bend according to their response to the refractive power of the glass. The degree of bending varies with wavelength, which means that the index of refraction also differs for the range of wavelengths. For example, in crown glass the index is 1.528 for violet and 1.514 for red.