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.
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