glassprism

A glass prism is an optical component made from transparent glass with flat, polished surfaces that intersect at a defined angle. When light enters a prism, it is refracted at the interfaces between air and glass, and, depending on the material and geometry, can be dispersed into its constituent wavelengths. The most common form is the triangular prism, though prisms can have other shapes for specialized functions.

In dispersion-prism configurations, shorter wavelengths bend more than longer wavelengths, producing a spectrum of colors. The amount of light deviation and spectral separation depends on the prism’s apex angle and the glass’s refractive index, which varies with wavelength. The underlying behavior is described by Snell’s law, and practical prisms are designed to minimize unwanted aberrations for a given application. Some prisms are designed primarily for reflection, such as roof prisms used in imaging instruments to reorient and invert images.

Materials and fabrication notes: prisms are typically made from optical glasses with high clarity, such as BK7 or F2, or from fused silica for broader wavelength ranges. Surfaces are precisely polished, and many prisms receive anti-reflective coatings to reduce losses at interfaces. The choice of glass and geometry determines dispersion, transmission, and imaging performance.

Applications cover a range of optical uses, including spectroscopy and prism-based spectrometers, imaging systems, cameras and binoculars (where roof-prisms correct orientation), and educational demonstrations of light dispersion. History highlights include Isaac Newton’s demonstration in the 1660s that white light comprises a spectrum when passed through a glass prism.