Question

What is chromatic aberration? How can it be minimized or eliminated?

Answer 1

Hint:While passing through the lens, the light gets refracted differently and it does not coincide with the focal length. This way, it falls behind or before the focal length of the lens and this is how such errors occur. This is when chromatic aberration occurs.
Chromatic aberrations can be reduced by:
-Increasing the focal length of the lens.
-Using an achromatic lens or achromat.
-Using low dispersion glass containing fluorite.

Complete answer:
In optics, the failure of a lens to focus all the colours to the same point is called chromatic aberration, it is caused by dispersion. Chromatic aberration manifests itself as "fringes" of colour along boundaries that separate dark and bright parts of the image.Chromatic aberration can be reduced by increasing the focal length of the lens where possible or by using an achromatic lens or achromat (in achromat lens, a compound lens is formed by assembling together materials with different dispersion).
The degree of correction can be further increased by combining more than two lenses of different composition, as seen in an apochromatic lens or apochromat. To reduce chromatic aberration, many types of glasses have been developed. These glasses have the property of low dispersion, most notably, glasses containing fluorite.

Note:Chromatic aberration is caused by lens dispersion. The refractive index of the lens depends on the wavelength of light and thus changes with it. In other words, different colours of light pass through a lens at different speeds, similar to how a prism separates white light into a rainbow.