Improved optical design for the Large Synoptic Survey Telescope (LSST)

Lynn G. Seppala

doi:10.1117/12.461389

24 December 2002 Improved optical design for the Large Synoptic Survey Telescope (LSST)

Lynn G. Seppala

Proceedings Volume 4836, Survey and Other Telescope Technologies and Discoveries; (2002) https://doi.org/10.1117/12.461389
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

This paper presents an improved optical design for the LSST, an f/1.25 three-mirror telescope covering 3.0 degrees full field angle, with 6.9 m effective aperture diameter. The telescope operates at five wavelength bands spanning 386.5 nm to 1040 nm (B, V, R, I and Z). For all bands, 80% of the polychromatic diffracted energy is collected within 0.20 arc-seconds diameter. The reflective telescope uses an 8.4 m f/1.06 concave primary, a 3.4 m convex secondary and a 5.2 m concave tertiary in a Paul geometry. The system length is 9.2 m. A refractive corrector near the detector uses three fused silica lenses, rather than the two lenses of previous designs. Earlier designs required that one element be a vacuum barrier, but now the detector sits in an inert gas at ambient pressure, with the last lens serving as the gas barrier. Small adjustments lead to optimal correction at each band. Each filter has a different axial thickness, and the primary and tertiary mirrors are repositioned for each wavelength band. Features that simplify manufacturing include a flat detector, a far less aspheric convex secondary (10 μm from best fit sphere) and reduced aspheric departures on the lenses and tertiary mirror. Five aspheric surfaces, on all three mirrors and on two lenses, are used. The primary is nearly parabolic. The telescope is fully baffled so that no specularly reflected light from any field angle, inside or outside of the full field angle of 3.0 degrees, can reach the detector.

Citation Download Citation

Lynn G. Seppala "Improved optical design for the Large Synoptic Survey Telescope (LSST)", Proc. SPIE 4836, Survey and Other Telescope Technologies and Discoveries, (24 December 2002); https://doi.org/10.1117/12.461389

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