Chromatic aberration

Definition

Chromatic aberration is a distortion in an image caused by the inability of a lens to focus all colors at the same convergence point. This results in fringes of color, usually purple or green, around objects seen through telescopes and other optical instruments.

5 Must Know Facts For Your Next Test

1. Caused by the different refractive indices for different wavelengths of light.
2. More prominent in simple lenses and cheaper telescopes without corrective elements.
3. Can be minimized using achromatic or apochromatic lenses which combine multiple types of glass.
4. Reflecting telescopes do not suffer from chromatic aberration as they use mirrors instead of lenses.
5. Chromatic aberration affects both visual observations and astrophotography.

Review Questions

• What causes chromatic aberration in telescopes?
• How can chromatic aberration be minimized in optical instruments?
• Why do reflecting telescopes not experience chromatic aberration?

Related terms

Achromatic Lens: A lens designed to limit the effects of chromatic and spherical aberrations.

Apochromatic Lens: A type of lens that brings three wavelengths into focus in the same plane, reducing chromatic aberration more effectively than an achromatic lens.

Spherical Aberration: A distortion occurring when light rays passing through a lens or reflecting off a mirror do not converge at a single focal point, leading to blurred images.