A hyperspectral camera based on a birefringent ultrastable common-path interferometer

Spectral imaging (or imaging spectroscopy) is a powerful technique that acquires the complete light spectrum at each point in the image of a scene. This can be obtained by a wide variety of methods. A first approach relies on placing band-pass spectral filters in front of a monochrome camera, thus acquiring the hyperspectral image at a limited number of spectral bands. A second class of techniques collects the whole continuous spectrum of each image point; an example is the combination of a dispersive spectrometer with a raster-scanning approach, at the cost of high losses imposed by the entrance slit of the spectrometer. An alternative approach combines imaging with Fourier-transform (FT) spectrometry [1]. This technique can retrieve in parallel the spectra for all pixels in a scene and is hence suited for imaging, but it requires controlling the delay with sub-cycle precision, which is very difficult to achieve with standard Michelson or Mach-Zehnder interferometers.