All Problems Diffraction of Light
Problem 5.148
Determine the minimum multiplication of a telescope with diameter of objective \(D=5.0 \mathrm{~cm}\) with which the resolving power of the objective is totally employed if the diameter of the eye's pupil is \(d_{0}=4.0 \mathrm{~mm}\).
5.148. Suppose \(\Delta \psi\) and \(\Delta \psi^{\prime}\) are the minimum angular separations resolved by the telescope's objective and the eye respectively \(\left(\Delta \psi=1.22 \lambda / D, \Delta \psi^{\prime}=1.22 \lambda / d_{0}\right) .\) Then the sought magnification of the telescope is \(\Gamma_{\min }=\Delta \psi^{\prime} / \Delta \psi=D / d_{0}=13\)