Applications of absolute surface metrology by transverse shifting

摘要

A novel and very simple technique has been developed for extracting absolute phase maps from laboratory Fizeauinterferometers, and that technique is generalized here to applications in interferometry and adaptive optics. In theoriginal implementation, the phase maps considered were those produced by an interferometer measuring the surface ofa high-precision flat mirror. The phase or surface shape measured in such a configuration is known only with respect tothe phase map of the interferometer's transmission flat, and so contains substantial errors when precise surfaces arebeing tested. By making two additional measurements with small lateral shifts of the surface under test, and differencingthese, maps of absolute phase differences between neighboring points on the test surface can be made. From these,standard wavefront reconstruction can recover an absolute phase map. Examples of the technique are considered here,including a novel diagnostic of common-path errors in adaptive optics systems. For an architecture in which thecommon path and the wavefront-sensor path can be adjusted in relative shear, it is possible to apply the requisitetransverse shifts and so derive an absolute phase map isolating embedded portions of the system optics.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.