Interferometric flatness testing of nonoptical surfaces.
An interferometric method of testing the flatness of nonoptical surfaces is described. The method consists essentially of introducing light to the surface at near grazing incidence; this is effected by using an isosceles glass prism, the base of which is the reference surface. The technique can utilize diffuse daylight as a light source and provides a quick and easy method of assessing the flatness of such items as smoothed glass flats prior to polishing, flat metal laps, and other nonoptical surfaces.
Briers
J D
JD