Astronomical spectrograph calibration with broad-spectrum frequency   combs
  Broadband femtosecond-laser frequency combs are filtered to spectrographically resolvable frequency-mode spacing, and the limitations of using cavities for spectral filtering are considered. Data and theory are used to show implications to spectrographic calibration of high-resolution, astronomical spectrometers. 
D.A. Braje, M.S. Kirchner, S. Osterman, T. Fortier, and S.A. Diddams