Computer generated holograms for testing aspheric lenses.

For the purpose of measuring aspheric surfaces, an improved type of computer generated hologram, named the inclined bar type hologram, is proposed. This hologram is characterized by inclined bars. The inclination angle for each bar is obtained from the calculated wavefront aberration of the test lens. A few problems with these computer generated holograms are analyzed, and the advantage of the inclined bar type hologram over the conventional one is demonstrated by experiment.