We report the laboratory experiment on a segmented mirror testbed that shows the use of a dispersed Rayleigh interferometer to phase segmented mirrors. Segment alignment of tip-tilt is fulfilled by overlapping diffraction pattern centroids of the three individual segments on the focal plane. A spherical interferometer is introduced to evaluate the performance of piston, tip-tilt sensing, and control closed-loop, and finally a total residual root-mean-square (RMS) surface error of about 45 nm is achieved, in which a typical error of about 20 nm is contributed by piston. These results demonstrate that the dispersed Rayleigh interferometer can successfully sense the piston of segmented mirrors and be used in phasing segmented telescopes under extensive studies.
© 2009 Chinese Optics Letters
(120.2830) Instrumentation, measurement, and metrology : Height measurements
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.1088) Instrumentation, measurement, and metrology : Adaptive interferometry
(120.6085) Instrumentation, measurement, and metrology : Space instrumentation
Shanshan Wang, Qiudong Zhu, Weirui Zhao, Lin Li, and Genrui Cao, "Performance of dispersed Rayleigh interferometer on the active cophasing and alignment testbed," Chin. Opt. Lett. 7, 1007-1009 (2009)