Scrambling and modal noise mitigation in the Habitable Zone Planet Finder fiber feed

Arpita Roy, Samuel Halverson, Suvrath Mahadevan, Lawrence W. Ramsey

Research output: Chapter in Book/Report/Conference proceedingConference contribution

25 Scopus citations


We present the baseline fiber feed design for the Habitable-zone Planet Finder (HPF), a precision radial velocity (RV) spectrograph designed to detect Earth analogs around M-dwarfs. HPF is a stabilized, fiber-fed, R∼50,000 spectrograph operating in the near-infrared (NIR) from 0.82 to 1.3 μm, and will be deployed on the Hobby- Eberly Telescope (HET) in Texas. While the essential function of the optical fibers is to deliver high throughput, this mode of light transport also provides the opportunity to introduce radial and azimuthal scrambling, which boosts instrument stability and thereby RV precision. Based on the unique requirements of HPF on the HET, we present initial tests showing very high scrambling gains via a compact scrambler in conjunction with octagonal fibers. Conversely, the propagation of light through the fibers injects modal noise, which can limit achievable RV precision. Laboratory tests of a custom-built mechanical agitator show significant gains over a static fiber feed. Overall, the fiber feed is designed to provide high relative throughput, excellent scrambling, and reliable modal noise suppression. We will also attempt to minimize focal ratio degradation (FRD) to the extent possible with the chosen configuration. HPF inculcates several other new technologies developed by the Penn State Optical-Infrared instrumentation group, including a rigorous calibration system, which are discussed separately in these proceedings.

Original languageEnglish (US)
Title of host publicationGround-Based and Airborne Instrumentation for Astronomy V
EditorsSuzanne K. Ramsay, Ian S. McLean, Hideki Takami
ISBN (Electronic)9780819496157
StatePublished - 2014
EventGround-Based and Airborne Instrumentation for Astronomy V - Montreal, Canada
Duration: Jun 22 2014Jun 26 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherGround-Based and Airborne Instrumentation for Astronomy V

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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