A dual cavity Fabry-Perot device for high precision Doppler measurements in astronomy

We propose a dual cavity Fabry-Perot interferometer as a wavelength calibrator and a stability tracking device for astronomical spectrograph. The FPI consists of two adjoining cavities engraved on a low expansion monoblock spacer. A low-finesse astro-cavity is intended for generating a uniform grid...

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Bibliographic Details
Published in:arXiv.org 2017-01
Main Authors: Banyal, Ravinder Kumar, Reiners, Ansgar
Format: Article
Language:English
Subjects:
Astronomy
Engraving
Fabry-Perot interferometers
Finite element method
Frequency standards
Holes
Optical frequency
Tracking devices
Vibration analysis
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Summary:We propose a dual cavity Fabry-Perot interferometer as a wavelength calibrator and a stability tracking device for astronomical spectrograph. The FPI consists of two adjoining cavities engraved on a low expansion monoblock spacer. A low-finesse astro-cavity is intended for generating a uniform grid of reference lines to calibrate the spectrograph and a high-finesse lock-cavity is meant for tracking the stability of the reference lines using optical frequency standards. The differential length changes in two cavities due to temperature and vibration perturbations are quantitatively analyzed using finite element method. An optimized mounting geometry with fractional length changes \(\Delta L/L \approx 1.5\times 10^{-12}\) is suggested. We also identify conditions necessary to suppress relative length variations between two cavities well below 10\(^{-10}\)~m, thus facilitating accurate dimension tracking and generation of stable reference spectra for Doppler measurement at 10 cms\(^{-1}\) level.
ISSN:2331-8422