PX284 - U1- resolution

when $x=\lambda$, destructive interference, ie. $\theta =\lambda /D$

angles of light rays defined to within $\sim \lambda /D$

therefore, cannot resolve rays less than $O(\lambda /D)$ apart

for circular aperture, require $\mathrm{\Delta }\theta >1.22\lambda /D$ to resolve light rays, which is called the rayliegh criterion