@inproceedings{9f4c0866e0534616b2669eba4f972744,
title = "Scanning pentaprism test for the GMT 8.4 m off-axis segments",
abstract = "The scanning pentaprism system for testing the 8.4 m off-axis segments for the Giant Magellan Telescope has recently been completed. The system uses a fiber source and a carriage mounted pentaprism to scan a 40 mm collimated beam across the surface of the segment under test. Since the scanning beam is parallel to the optical axis of the parent mirror, it comes to focus on a detector at the telescope's prime focus, where displacement of the spot is proportional to the slope error. A second collimated beam from a stationary reference pentaprism is used to compensate for any changes in the relative positions of the optical components during testing. The optical components are suspended over the mirror on a rail system that can be rotated so that scans can be made across any diameter of the segment. The test is capable of measuring wavefront slope errors to 1 μrad rms, adequate to verify that power, astigmatism, coma, and other low-order aberrations are small enough to be corrected easily at the telescope with the segment's active support system.",
keywords = "Aspherics, Optical testing, Telescope",
author = "Richard Allen and Peng Su and Burge, {James H.} and Brian Cuerden and Martin, {Hubert M.}",
year = "2010",
doi = "10.1117/12.857901",
language = "English (US)",
isbn = "9780819482297",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
booktitle = "Modern Technologies in Space- and Ground-Based Telescopes and Instrumentation",
note = "Modern Technologies in Space- and Ground-Based Telescopes and Instrumentation ; Conference date: 27-06-2010 Through 02-07-2010",
}