Projection moire technique for contouring injection-molded parabolic reflectors

Testing injection molded aspheres, with large deviations from spherical is difficult. One solution is to use a long wavelength interferometer, such as an infrared interferometer. Another solution is to use moire. This paper presents the use of a projection moire system to test the surface shape of an injection molded f/0.1 parabolic reflector. The theory of moire and its effective wavelength is presented. A projection system is constructed and data taken for a reflector is shown. Finally, some alignment errors associated with the system and how to correct them is presented.