Photonics Dictionary


Dispersion refers to the phenomenon where different wavelengths (colors) of light travel at different speeds when passing through a medium. This variation in the speed of light for different colors causes the light to spread out or disperse, resulting in the separation of the colors.

The most common example of dispersion is the separation of white light into its constituent colors when it passes through a prism. Sir Isaac Newton first demonstrated this phenomenon by using a glass prism to break white light into a spectrum of colors—red, orange, yellow, green, blue, indigo, and violet.

The dispersion occurs because the refractive index of a medium (such as glass or water) is wavelength-dependent. This means that different colors of light experience different amounts of bending as they pass through the medium. The shorter wavelengths (blue and violet) are bent more than the longer wavelengths (red and orange).

The dispersion of light is a crucial concept in optics and is relevant in the design of lenses and optical systems. Correcting for dispersion is important in minimizing chromatic aberrations, which can affect the quality of images produced by optical instruments such as cameras and telescopes. Special lens designs and materials are often employed to manage and control dispersion in optical systems.






Presented by Dr. Gerard Wysocki, Princeton University

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