Laser Frequency Combs for Astronomical Observations

By T. Steinmetz, T. Wilken, C. Araujo-Hauck, Ronald Holzwarth, T. Hänsch, L. Pasquini, A. Manescau, S. D’odorico, M. Murphy, T. Kentischer and 2 more. Science, 2008

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A direct measurement of the universe's expansion history could be made by observing in real time the evolution of the cosmological redshift of distant objects. However, this would require measurements of Doppler velocity drifts of ∼1 centimeter per second per year, and astronomical spectrographs have not yet been calibrated to this tolerance. We demonstrated the first use of a laser frequency comb for wavelength calibration of an astronomical telescope. Even with a simple analysis, absolute calibration is achieved with an equivalent Doppler precision of ∼9 meters per second at ∼1.5 micrometers—beyond state-of-the-art accuracy. We show that tracking complex, time-varying systematic effects in the spectrograph and detector system is a particular advantage of laser frequency comb calibration. This technique promises an effective means for modeling and removal of such systematic effects to the accuracy required by future experiments to see direct evidence of the universe's putative acceleration.

View Paper: https://www.semanticscholar.org/paper/b070b40a738e2ef51ec56d490cc5faaddf6014db

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Citations in the corpus

Exoplanet Atmospheres: Physical Processes (2010, methodology): “These other methods include space-based astrometry (see Shao & Nemati 2009 and references therein) or potentially ground-based radial velocity with the new development of the astro frequency comb spectrograph (Steinmetz et al. 2008; Li et al. 2009).”
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.”
High‐precision calibration of spectrographs (2010, background): “A very promising approach is based upon the use of spectrally filtered laser frequency combs (LFCs), which are the best candidates to become the ideal tool for improved calibration (e.g. Murphy et al. 2007; Braje et al. 2008; Li et al. 2008; Steinmetz et al. 2008).”
Varying Constants, Gravitation and Cosmology (2010, background): “. The metal lines have intrinsic width of a few km/s. One can thus expect improvements from higher spectral resolution. Progresses consercning the calibration are also expected, using e.g. laser comb [474]. Let us just mention, the EXPRESSO (Echelle Spectrograph for PREcision Super Stable Observatio”
DETECTING PLANETS AROUND VERY LOW MASS STARS WITH THE RADIAL VELOCITY METHOD (2009, methodology): “For our purpose, we have not considered calibration using a laser comb (Steinmetz et al. 2008) or an etalon, which essentially follow the same principle as the ThAr calibration.”
Cavity-enhanced direct frequency comb spectroscopy (2008, background): “spacing of tens of GHz is desired [171–173].”