In segmented-mirror telescopes, wave-front discontinuities caused by segment misalignment are a major problem because they severely degrade optical performance. While angular misalignments are usually measured with deflectometric wave-front sensors (e.g., Shack-Hartmann sensors), a number of techniques have been proposed for the measurement of vertical discontinuities (pistons). In earlier papers we presented an instrument called UPC-ZEBRA that uses a novel interferometric technique to measure piston error during the daytime with an uncertainty of 5 nm within a 30-μm range. Here we present the most representative results obtained during the testing stage and a detailed analysis of error sources. The main modifications to be introduced for the instrument’s use as a phasing calibration system are also outlined.
© 2004 Optical Society of America
(110.6770) Imaging systems : Telescopes
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation
(350.1260) Other areas of optics : Astronomical optics
Agustí Pintó, Ferran Laguarta, Roger Artigas, and Cristina Cadevall, "Testing and applicability of the UPC-ZEBRA interferometer as a phasing system in segmented-mirror telescopes," Appl. Opt. 43, 1091-1096 (2004)