## University Physics with Modern Physics (14th Edition)

Use Rayleigh’s criterion, $sin \theta_1=1.22\frac{\lambda}{D}$. $$D =1.22\frac{\lambda}{ sin \theta_1}$$ $$D =1.22\frac{550\times10^{-9}m }{ sin (1/60)^{\circ}}=2.3\times10^{-3}m$$