  Ghost imaging is an unconventional imaging technique that generates high
resolution images by correlating the intensity of two light beams, neither of
which independently contains useful information about the shape of the object.
Ghost imaging has great potential to provide robust imaging solutions in the
presence of severe environmental perturbations, and has been demonstrated both
in the spatial and temporal domains . Here, we exploit recent progress in
ultrafast real-time measurement techniques to demonstrate ghost imaging in the
frequency domain using a continuous spectrum from an incoherent supercontinuum
(SC) light source. We demonstrate the particular application of this ghost
imaging technique to broadband spectroscopic measurements of methane
absorption, and our results offer novel perspectives for remote sensing in low
light conditions, or in spectral regions where sensitive detectors are lacking.
