Question

A crossed lens is used to minimize a spherical aberration. The ratio of the radii of curvatures is ( $\mu =1.5$) :

• A. $1/6$
• B. $-1/6$
• C. $6$
• D. $-6$

Answer 1

Answer: (B)

$-1/6$

A crossed lens is used to minimize a spherical aberration and the radius of curvature $R_1$ and $R_2$ of the two surfaces should satisfy the relation

$\frac{R_1}{R_2}=\frac{2{\mu }^2-\mu -4}{\mu (1+2\mu )}$

Given : $\mu =1.5$,

$\therefore$ $\frac{R_1}{R_2}=\frac{2(1.5{)}^2-1.5-4}{1.5(1+2\times 1.5)}=\frac{-1}{6}$