LSST Telescope primary/tertiary mirror cell assembly

Douglas Neill; Edward Hileman

doi:10.1117/12.857428

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4 August 2010 LSST Telescope primary/tertiary mirror cell assembly

Douglas Neill, Edward Hileman

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Proceedings Volume 7733, Ground-based and Airborne Telescopes III; 77332Q (2010) https://doi.org/10.1117/12.857428
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

Abstract

The Large Synoptic Survey Telescope (LSST) primary/tertiary (M1M3) mirror cell assembly supports both on-telescope operations and off-telescope mirror coating. This assembly consists of the M1M3 monolith mirror, the mirror support systems, the thermal control system, a stray light baffle ring, a laser tracker interface and the supporting steel structure. During observing the M1M3 mirror is actively supported by figure control actuators and a hexapod. The M1M3 figure control actuators distribute the load to safely support the glass mirror and actively control its shape. The position of the mirror relative to the mirror cell is controlled by a set of six hardpoints (displacement controlled actuators) that form a large hexapod. When the active system is not operating the mirror is supported by a separate passive support system. The center of the mirror cell supports a laser tracker which measures the relative position of the camera and secondary mirror for alignment by their hexapods. The mirror cell design height of 2 meters provides ample internal clearance for installation and maintenance of mirror support and thermal control systems. The mirror cell also functions as the bottom of the vacuum chamber during coating. Consequently, to withstand the vacuum-induced stress the M1M3 mirror cell will be fabricated from higher strength steel. The vacuum-induced mirror cell deformations must be isolated from the mirror support system to prevent overstressing the mirror. This is accomplished by utilizing separate truss support systems for the top deck and the vacuum boundary.

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Douglas Neill and Edward Hileman "LSST Telescope primary/tertiary mirror cell assembly", Proc. SPIE 7733, Ground-based and Airborne Telescopes III, 77332Q (4 August 2010); https://doi.org/10.1117/12.857428

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