Telescope Coalignment System For The Multiple Mirror Telescope(MroAT)

David McDonough

doi:10.1117/12.959465

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31 December 1980 Telescope Coalignment System For The Multiple Mirror Telescope(MroAT)

David McDonough

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Proceedings Volume 0251, Optical Alignment I; (1980) https://doi.org/10.1117/12.959465
Event: 24th Annual Technical Symposium, 1980, San Diego, United States

Abstract

This paper describes the coalignment system for the six 1.8 m astronomical telescopes of the Multiple Mirror Telescope. Emphasis is on individual component alignment and the achievement and maintenance of particular image configurations. The system employs a HeNe laser as an artificial star with its light colli mated by a 0.7 m guide telescope and trasferred to the 1.8 m telescopes via periscopes and retroreflectors. Silicon detectors sense laser image position deviations due to mirror tilts or displacements, and generate signals to actively correct pointing errors via 3 axis motion of the tel Cassegrain secondaries. Procedures are given for aligning the laser beamsplitters, collimating the beams, and aligning the detectors sequentially to arrive at a desired configuration. Keys to the operation are the use of a pinhole in the guide telescope's focal plane as a defining point for the laser source, the active stabilization of the guide telescope's focus, the stability of the periscopes, and the use of remotely-controlled thin wedge prisms to change each laser beam's position when reconfiguring any one telescope. Tests of star tracking show typical coalignment to <1.0 arc second RMS. A discussion of problems encountered is included.

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David McDonough "Telescope Coalignment System For The Multiple Mirror Telescope(MroAT)", Proc. SPIE 0251, Optical Alignment I, (31 December 1980); https://doi.org/10.1117/12.959465

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