HYBRID WEDGE PLATE-GRATING INTERFEROMETER FOR COLLIMATION TESTING

A new type of collimation testing technique using a single wedge plate in conjunction with a dual-field grating has been described. interfer ence pattern produced by a wedge plate illuminated by the test beam is superposed on a grating to get moire fringes. By using two different types of dual-field gratings, two testing configurations are obtained. These dual-field moire patterns provide self-referencing and improved sensitivity in collimation testing. The principle of the proposed tec hniques and experimental results are presented. (C) 1998 Society of Ph oto-Optical instrumentation Engineers. [S0091-3286(98)01105-2].