Optical fabrication of the MMT adaptive secondary mirror

Hubert M. Martin; James H. Burge; Ciro Del Vecchio; Lee R. Dettmann; Stephen M. Miller III; Bryan Keener Smith; Francois P. Wildi

doi:10.1117/12.390364

7 July 2000 Optical fabrication of the MMT adaptive secondary mirror

Hubert M. Martin, James H. Burge, Ciro Del Vecchio, Lee R. Dettmann, Stephen M. Miller III, Bryan Keener Smith, Francois P. Wildi

Author Affiliations +

Proceedings Volume 4007, Adaptive Optical Systems Technology; (2000) https://doi.org/10.1117/12.390364
Event: Astronomical Telescopes and Instrumentation, 2000, Munich, Germany

Abstract

We describe the optical fabrication of the adaptive secondary mirror for the MMT. The 640 mm f/15 secondary consists of a flexible glass shell, 1.8 mm thick, whose shape is controlled by 336 electromagnetic actuators. It is designed to give diffraction-limited images at a wavelength of 1 micron. For generating and polishing, the shell was supported by attaching it to a rigid glass blocking body with a thin layer of pitch. It could then be figured and measured using techniques developed for rigid secondaries. The highly aspheric surface was polished with a 30 cm stressed lap and small passive tools, and measured using a swing-arm profilometer and a holographic test plate. The goal for fabrication was to produce diffraction-limited images in the visible, after simulated adaptive correction using only a small fraction of the typical actuator forces. This translates into a surface accuracy of less than 19 nm rms with correction forces of less than 0.05 N rms. We achieved a surface accuracy of 8 nm rms after simulated correction with forces of 0.02 N rms.

Citation Download Citation

Hubert M. Martin, James H. Burge, Ciro Del Vecchio, Lee R. Dettmann, Stephen M. Miller III, Bryan Keener Smith, and Francois P. Wildi "Optical fabrication of the MMT adaptive secondary mirror", Proc. SPIE 4007, Adaptive Optical Systems Technology, (7 July 2000); https://doi.org/10.1117/12.390364

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