Chromatic aberration, the inability of a simple lens to focus all colors of light to the same focal point, is reduced in astronomical telescopes by
A) adding a carefully shaped mirror to the lens to produce a lens-mirror combination.
B) combining two lenses of different shape, made from the same kind of glass.
C) bending the lens in its mounting.
D) combining two lenses of different shape, made from different kinds of glass.

Question

Quizplus · Accepted Answer

Chromatic aberration is reduced by combining two lenses of different shapes made from different kinds of glass. This combination, known as an achromatic doublet, corrects for the different refractive indices of colors, allowing them to focus at the same point and thus reducing chromatic aberration.

Chromatic Aberration, the Inability of a Simple Lens to Focus