High‐precision wavelength calibration of astronomical spectrographs with laser frequency combs

By M. Murphy, T. Udem, Ronald Holzwarth, A. Sizmann, L. Pasquini, C. Araujo-Hauck, H. Dekker, S. D’odorico, M. Fischer, T. Hansch and 6 more. 2007

344 citations recorded by the source corpus.

ABSTRACT We describe a possible new technique for precise wavelength calibration of high-resolutionastronomical spectrographs using femtosecond-pulsed mode-locked lasers controlled by sta-ble oscillators such as atomic clocks. Such ‘frequency combs’ provide a series of narrowmodes which are uniformly spaced according to the laser’s pulse repetition rate and whoseabsolute frequencies are known a priori with relative precision better than 10 −12 . Simula-tions of frequency comb spectra show that the photon-limited wavelength calibration preci-sion achievable with existing echelle spectrographs should be ∼1cms −1 when integrated overa 4000A range. Moreover, comb spectra may be used to accurately characterise distortionsof the wavelength scale introduced by the spectrograph and detector system. The simulationsshow that frequency combs with pulse repetition rates of 5–30GHz are required, given thetypical resolving power of existing and possible future echelle spectrographs. Achieving suchhigh repetition rates, together with the desire to produce all comb modes with uniform inten-sity over the entire optical range, represent the only signiﬁcant challenges in the design ofa practical system. Frequency comb systems may remove wavelength calibration uncertain-ties from all practical spectroscopic experiments, even those combining data from diﬀerenttelescopes over many decades.Key words: instrumentation: spectrographs – instrumentation: detectors – methods: labora-tory – techniques: spectroscopic

Subfields: Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/d429d20eda1c638df6348c87ef5a6f57a98da978

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

State of the Field: Extreme Precision Radial Velocities (2016, background): “…(e.g. G-CLEF, SALT-HRS, and KiwiSpec) to maximize velocity stability: dual-shell thermal enclosure, vacuum-enclosed echelle grating, octagonal fibres, an innovative ball-lens double scrambler, and wavelength calibration with an ultra-stablized pulsedlaser frequency comb (Murphy et al. 2007).”
ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations (2010, background): “Therefore, ESPRESSO will integrate a new developed laser frequency comb [12], [13], which provides stability and accuracy of better than 10, well below the mm s regime.”
Cosmic dynamics in the era of Extremely Large Telescopes (2008, background): “This system provides a series of uniformly spaced, narrow lines whose absolute positions are known a priori with relative precision better than 10−12 (see Murphy et al. 2007, for details).”
High‐precision calibration of spectrographs (2010, methodology): “Two FPCs with free spectral ranges of m1fr and m2m1fr are used in series to suppress the unwanted LFC modes (e.g. Murphy et al. 2007) (see Fig.”