LSST M1M3 active mirror support system optimized to accommodate rapid telescope motions

Felipe Daruich; Douglas Neill; Michael Warner; Edward Hileman; Myung Cho; Christoph Dribusch; Constanza Araujo; Michael Booth; Christopher Contaxis; Ron Harris; Brian Johnson; Garry Knight; Neill Mills; Gary Muller; Edward Stover; Oliver Wiecha; Bo Xin

doi:10.1117/12.2313724

6 July 2018 LSST M1M3 active mirror support system optimized to accommodate rapid telescope motions

Felipe Daruich, Douglas Neill, Michael Warner, Edward Hileman, Myung Cho, Christoph Dribusch, Constanza Araujo, Michael Booth, Christopher Contaxis, Ron Harris, Brian Johnson, Garry Knight, Neill Mills, Gary Muller, Edward Stover, Oliver Wiecha, Bo Xin

Author Affiliations +

Proceedings Volume 10700, Ground-based and Airborne Telescopes VII; 107003G (2018) https://doi.org/10.1117/12.2313724
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

The Large Synoptic Survey Telescope is an 8.4m telescope now in construction on Cerro Pachón, in Chile. This telescope is designed to conduct a 10-year survey of the southern sky in which it will map the entire night sky every few nights. In order to achieve this goal, the telescope mount has been designed to achieve high accelerations that will allow the system to change the observing field in just 2 seconds. These rapid slews will subject the M1M3 mirror to high inertial and changing gravitational forces that has to be actively compensated for in order to keep the mirror safe, aligned, and properly figured during operations. The LSST M1M3 active support system is composed of six “hard point” actuators and 156 pneumatic actuators. The hard points define the mirror position in the mirror cell (with little or no applied force) and hold that position while observing in order to maintain the alignment of the telescope optics. The pneumatic actuators provide the force-distributed mirror support plus a known (static) figure correction as well as dynamic optical figure optimizations coming from other components of the Active Optics System. Optimizing this mirror support system required the introduction of innovative control concepts in the control loops (Inner and Outer). The Inner Loop involves an extensive pressure control loop to ensure precise force feedback for each pneumatic actuator while the Outer Loop includes telescope motion sensors to provide the real-time feedback to compensate for the changing external inertial and gravitational forces. These optimizations allow the mirror support system to maximize the hard point force-offloading while keeping the glass safe when slewing and during seismic events.

Citation Download Citation

Felipe Daruich, Douglas Neill, Michael Warner, Edward Hileman, Myung Cho, Christoph Dribusch, Constanza Araujo, Michael Booth, Christopher Contaxis, Ron Harris, Brian Johnson, Garry Knight, Neill Mills, Gary Muller, Edward Stover, Oliver Wiecha, and Bo Xin "LSST M1M3 active mirror support system optimized to accommodate rapid telescope motions", Proc. SPIE 10700, Ground-based and Airborne Telescopes VII, 107003G (6 July 2018); https://doi.org/10.1117/12.2313724

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
16 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Actuators

Mirrors

Telescopes

Control systems

Large Synoptic Survey Telescope

Sensors

Systems modeling

Show All Keywords

Keywords/Phrases

Search In:

Publication Years