Steinmetz Tilo, Wilken Tobias, Araujo-Hauck Constanza, Holzwarth Ronald, Hänsch Theodor W, Pasquini Luca, Manescau Antonio, D'Odorico Sandro, Murphy Michael T, Kentischer Thomas, Schmidt Wolfgang, Udem Thomas
Max-Planck Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany.
Science. 2008 Sep 5;321(5894):1335-7. doi: 10.1126/science.1161030.
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 approximately 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 approximately 9 meters per second at approximately 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.
通过实时观测遥远天体宇宙学红移的演化，可以直接测量宇宙的膨胀历史。然而，这需要测量每年约每秒1厘米的多普勒速度漂移，而天文光谱仪尚未校准到这种精度。我们展示了首次将激光频率梳用于天文望远镜的波长校准。即使进行简单分析，在约1.5微米处也能实现等效多普勒精度约为每秒9米的绝对校准——超过了当前的先进精度。我们表明，跟踪光谱仪和探测器系统中复杂的、随时间变化的系统效应是激光频率梳校准的一个特别优势。这项技术有望成为一种有效的手段，用于对这些系统效应进行建模并消除，以达到未来实验所需的精度，从而直接观测到宇宙假定加速的证据。
