| 摘要 |
A full-field, geometrically-desensitized interferometer (GDI) instrument incorporates a combination of diffractive optics and conventional optics to perform beam splitting and recombining operations during a surface profilometry operation. Symmetrically-positioned inbound and outbound optical subassemblies typically are arranged to direct an inbound collimated beam from a light generator to the profiled surface of a test object and to direct outbound reflected beams to an imaging device as a single recombined outbound interference beam. The optical path difference between the two inbound beams or between the two reflected outbound beams can be substantially independent of field position on a perfectly flat sampled surface adjusted for null fringes-hence producing the desired full-field effect. The resultant instrument, in addition to being capable of full-field imaging, exhibits several advantages when compared to grating-based GDI instruments including 1) a larger working distance, 2) the employment of readily-available blazed diffraction gratings or the like, and 3) the ability to transmit light with higher efficiency and without producing ghost images.
|
