title: Interferometric flatness testing of nonoptical surfaces.
abstract: 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.
authors.forename: J D
authors.initials: JD
authors.lastname: Briers