Aspheric optical test plate assembly

Claim 1

An aspheric optical test plate assembly for comparing the contour of an aspheric optical surface at a first location with the known contour of an aspheric optical surface at another location, said aspheric optical test plate assembly including: A. An optical test plate having the shape of a segment of a sphere, said optical test plate including a top surface, a bottom surface and an edge between said top surface and said bottom surface; B. A pair of adjustable members for selectively applying pressure to the top surface of said optical test plate at locations near the edge of said optical test plate; and C. A fixture for retaining said optical test plate, said fixture including a reaction ring positioned above said optical test plate, said reaction ring having a diameter substantially equivalent to the diameter of said optical test plate, a pair of brackets for supporting said reaction ring above said optical test plate, each of said brackets having a first end fastened to said reaction ring and a second end fastened to the edge of said optical test plate, said brackets being spaced 180° apart from each other on said reaction ring and on the edge of said optical test plate, said reaction ring further including means for receiving a pair of adjustable members to permit said adjustable members to be adjusted to selectively apply pressure to said optical test plate, each of said adjustable members being spaced substantially 90° apart from one of said brackets on said reaction ring; Whereby the comparison between the contour of an aspheric optical surface at said first location with the known contour of the optical surface at another location may be made by first placing the optical test plate assembly on the aspheric optical surface at said another location and adjusting the shape of said optical test plate to the shape of said aspheric optical surface at said another location by adjusting said adjustable members to selectively deform the bottom surface of said optical test plate and thereafter moving said aspheric optical test plate assembly to said first location and using a light source to produce an interference pattern at said first location to compare the contour of the aspheric optical surface at the first location with the shape of the bottom surface of said optical test plate.