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Keck Planet Finder: Zerodur optical bench mechanical design

Smith, Christopher and Gibson, Steven R. and Howard, Andrew W. and Edelstein, Jerry and Wishnow, Edward H. and Rider, Kodi (2018) Keck Planet Finder: Zerodur optical bench mechanical design. In: Ground-based and Airborne Instrumentation for Astronomy VII. Proceedings of SPIE. No.10702. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 107026Y. ISBN 9781510619579.

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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.

Item Type:Book Section
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Howard, Andrew W.0000-0001-8638-0320
Additional Information:© 2018 Society of Photo-optical Instrumentation Engineers (SPIE). The authors thank the Heising-Simons Foundation; the W.M. Keck Foundation; the University of California, Berkeley; the California Institute of Technology; and the University of Hawaii for financial support of KPF. The authors also wish to thank Winlight Systems for their valuable contributions to the designs of the reformatter and cameras, as well as the DESI project for sharing both their camera designs and their expertise with optical fibers.
Group:Astronomy Department
Funding AgencyGrant Number
Heising-Simons FoundationUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
University of California, BerkeleyUNSPECIFIED
University of HawaiiUNSPECIFIED
Subject Keywords:Spectrometer, Exoplanets, Doppler Spectroscopy, Zerodur, Optical Bench
Series Name:Proceedings of SPIE
Issue or Number:10702
Record Number:CaltechAUTHORS:20190109-111011829
Persistent URL:
Official Citation:Christopher Smith, Steven R. Gibson, Andrew W. Howard, Jerry Edelstein, Edward H. Wishnow, Kodi Rider, "Keck Planet Finder: Zerodur optical bench mechanical design," Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 107026Y (9 July 2018); doi: 10.1117/12.2313969
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92168
Deposited By: Tony Diaz
Deposited On:09 Jan 2019 19:20
Last Modified:03 Oct 2019 20:41

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