Abstract

An externally dispersed interferometer (EDI) is the series combination of a fixed delay interferometer (Michelson) with an external dispersive spectrograph. Its performance combines the compactness and beamshape insensitivity of a FTS with the order of magnitude or more lower photon noise of a grating spectrograph relative to the FTS. A broadband moiré effect heterodynes high detail spectral information to low spatial frequencies resolved by the grating spectrograph. The iodine spectrum was measured while stepping the Michelson delay in a few large increments, to 4.6 cm maximum delay. The reconstructed spectrum has a Gaussian spectral resolution approximately 6 times greater than the grating spectrograph used without the interferometer.

© 2005 Optical Society of America