Hamburg 2009 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 24: Präzisionsmessungen II
Q 24.7: Talk
Tuesday, March 3, 2009, 18:00–18:15, Audi-A
Calibration of Astronomical Spectrometers with Frequency Combs — •Tobias Wilken1, Tilo Steinmetz1, Phillip Vilar-Welter1, Constanza Araujo-Hauck2, Ronald Holzwarth1, Theodor W. Hänsch1, and Thomas Udem1 — 1Max-Planck-Institut für Quantenoptik, Garching — 2European Southern Observatory, Garching
In astronomy the need for ever more precise measurements of spectral lines has led to a point where the traditional calibration sources - spectral lamps - are not sufficient any longer. For the next generation of telescopes new calibration techniques have to be developed to increase the precision with which stellar light can be measured.
Frequency combs - limited in their precision only by the atomic clock they are locked to - have the ability to achieve calibrations with virtually unlimited accuracy. A level of better than 10−9 would be needed e.g. to detect extrasolar earthlike planets or directly observe the (accelerating) expansion of the universe.
We have set up a frequency comb based on a previously unreported Yb-doped fiber laser. For the indiviual modes to be resolvable with a spectrometer the mode spacing has been increased up to several GHz with a Fabry-Perot cavity. First test measurements at a solar telescope on Tenerife have been successfully performed and the next campaign at the HARPS spectrometer in Chile are in preparation.