Large-aperture interferometer with local reference beam

Abstract

A large-aperture interferometer has been devised by adding a local reference-beam-generating interferometer to a schlieren system. Two versions of the interferometer were demonstrated, one employing 12.7-cm diam schlieren optics, the other employing 30.48-cm diam parabolic mirrors in an off-axis system. In the latter configuration, a cylindrical lens was introduced near the light source to correct for astigmatism. A zone plate was a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed.