Interferometers with self-pumped phase-conjugate mirror for testing aspherical and cylindrical surfaces

Self-pumped phase-conjugate mirrors (SPPCM) on the base of photorefractive crystals are able to produce the phase-conjugate replica of an incoming wave. That is within certain limits independent of the incoming wave front. One conclusion of that is the possibility of aberration compensation in interferometers. Hence the application of SPPCM offers new possibilities for interferometric tests, especially in fields where classical methods reach their limits. We have built up an phase-shifting interferometer for testing cylindrical and aspherical surfaces incorporating a SPPCM. The optics for generating the wave front adapted to the surface under test is placed in the entrance arm of the interferometer. For testing aspherical surfaces we used a computer-generated hologram. The SPPCM is located in the reference arm. We will discuss the advantages and disadvantages of this new approach and present the results of testing such surfaces.