Sparrow limit of resolution of circular apertures with a ring-shaped II-phase changing filter, in partially coherent light

Sparrow criterion has been used to study the limit of resolution of two partially coherent point sources. We consider circular apertures with a ring-shaped II phase changing filter. The results are presented graphically. When the point sources are in phase opposition, an infinite degree of resolution is possible because the composite intensity at the middle point is always zero. The practical limitation imposed by the stray light in the image however prevents an « infinite » degree of resolution.