Abstract

For the null Ronchi test1 it is necessary to produce, with the help of a computer, the null Ronchi ruling. When using this ruling the observed pattern is a series of straight interference fringes. In the present work, instead of using a computer, a big ronchigram or screen with straight bands that covers the surface under test is used, and the null ruling is photographed on a film at a certain observing plane. Once this process is completed, the obtained null grating allows the observation of the straight interference fringes, if the same surface is used. However, if the same null ruling is used for testing some other similar surfaces, a different Ronchigram will be seen if there are errors in the tested surfaces.

© 1991 Optical Society of America