Final design of the LSST hexapods and rotator

Ryan Sneed; Douglas R. Neill; Scott Kidney; Constanza Araujo; William Gressler; Paul J. Lotz; Dave Milles; Jacques Sebag; Thomas A. Sebring; Mickael Warner; Oliver Wiecha

doi:10.1117/12.2231327

27 July 2016 Final design of the LSST hexapods and rotator

Ryan Sneed, Douglas R. Neill, Scott Kidney, Constanza Araujo, William Gressler, Paul J. Lotz, Dave Milles, Jacques Sebag, Thomas A. Sebring, Mickael Warner, Oliver Wiecha

Author Affiliations +

Proceedings Volume 9906, Ground-based and Airborne Telescopes VI; 99060K (2016) https://doi.org/10.1117/12.2231327
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

Abstract

The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the Cerro Pachón summit in Chile. Both the Secondary Mirror (M2) Cell Assembly and Camera utilize hexapods to facilitate optical positioning relative to the Primary/Tertiary (M1M3) Mirror. A rotator resides between the Camera and its hexapod to facilitate tracking. The final design of the hexapods and rotator has been completed by Moog CSA, who are also providing the fabrication and integration and testing. Geometric considerations preclude the use of a conventional hexapod arrangement for the M2 Hexapod. To produce a more structurally efficient configuration the camera hexapod and camera rotator will be produced as a single unit. The requirements of the M2 Hexapod and Camera Hexapod are very similar; consequently to facilitate maintainability both hexapods will utilize identical actuators. The open loop operation of the optical system imposes strict requirements on allowable hysteresis. This requires that the hexapod actuators use flexures rather than more traditional end joints. Operation of the LSST requires high natural frequencies, consequently, to reduce the mass relative to the stiffness, a unique THK rail and carriage system is utilized rather than the more traditional slew bearing. This system utilizes two concentric tracks and 18 carriages.

Citation Download Citation

Ryan Sneed, Douglas R. Neill, Scott Kidney, Constanza Araujo, William Gressler, Paul J. Lotz, Dave Milles, Jacques Sebag, Thomas A. Sebring, Mickael Warner, and Oliver Wiecha "Final design of the LSST hexapods and rotator", Proc. SPIE 9906, Ground-based and Airborne Telescopes VI, 99060K (27 July 2016); https://doi.org/10.1117/12.2231327

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