Bragg gratings in multi-mode fiber optics for wavelength calibration of GAIA and RAVE spectra

Abstract

We propose a new technique, the use of FBGs (fiber Bragg gratings), for accurate, easy and low cost wavelength calibration of GAIA, RAVE and follow-ups spectra at local Observatories. FBGs mark the spectra with absorption lines, freely defined in number and position during the fibers manufacturing. The process goes in parallel with the science exposure and through the same optical train and path, thus ensuring the maximum return in wavelength calibration accuracy. Plans to manufacture and test FBGs for the CaII/Paschen region are underway at the Astronomical Observatory of Padova.