Spherical aberration in a thin lens can be reduced by

Options

A. using a monochromatic light
B. using a doublet combination
C. using a circular annular mark over the lens
D. increasing the size of the lens

Answer

C

Explanation

Spherical aberration occurs due to the inability of a lens to converge marginal rays of the same wavelength to the focus as it converges the paraxial rays. This can be done by using a circular annular mask over the lens.