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Proceedings Paper

Keck Planet Finder: Zerodur optical bench mechanical design
Author(s): Christopher Smith; Steven R. Gibson; Andrew W. Howard; Jerry Edelstein; Edward H. Wishnow; Kodi Rider
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Paper Abstract

The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development for the W.M. Keck Observatory. To measure Doppler shifts to 0.5 m/s or better requires some of the optics be stable to 2 nm vertically and 2 nrad in pitch angle throughout a potentially one hour long observation. One traditional approach to this thermal stability problem is to build a metal bench and then control the spectrometer thermal environment to milli-Kelvin levels. An alternative approach used by KPF is to employ a Zerodur bench of extremely low coefficient of expansion (CTE), which relaxes the thermal stability required for the spectrometer assembly. Furthermore, Zerodur optics with integral mounts are used where possible, and are placed in contact with the bench through Zerodur shims. Springs are used to preload the optics and shims within pockets machined into the Zerodur bench. We will describe how this approach has been adapted for each optic (some of which are 450 mm high with a mass of 30 kg), and how the system meets our earthquake survival requirement of 0.92 g. This mounting scheme allows us to avoid using high-CTE metals or adhesives within the optic mounting system, and therefore fully exploit the high thermal stability of the Zerodur optical bench.

Paper Details

Date Published: 9 July 2018
PDF: 20 pages
Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 107026Y (9 July 2018); doi: 10.1117/12.2313969
Show Author Affiliations
Christopher Smith, Space Sciences Lab. (United States)
Steven R. Gibson, Space Sciences Lab. (United States)
Andrew W. Howard, California Institute of Technology (United States)
Space Sciences Lab. (United States)
Jerry Edelstein, Space Sciences Lab. (United States)
Edward H. Wishnow, Space Sciences Lab. (United States)
Kodi Rider, Space Sciences Lab. (United States)

Published in SPIE Proceedings Vol. 10702:
Ground-based and Airborne Instrumentation for Astronomy VII
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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