Side band Ronchi test

Appl Opt. 1976 Sep 1;15(9):2220-2. doi: 10.1364/AO.15.002220.

Abstract

Using holographic techniques a Ronchi ruling with carrier may be generated which has the property of giving highly defined Ronchi fringes, instead of the diffraction-blurred fringes produced in the normal test. This procedure can be generalized to include the case of circular fringes.