Patent ID: 7433044

Claim:
A Sagnac Fourier transform spectrometer comprising: a beamsplitter arranged to receive a substantially collimated input beam of light, split said input beam into first and second beams, and recombine said first and second beams into an output beam path; first and second diffraction gratings arranged with respect to said beamsplitter to form an optical path that extends from said beamsplitter to said first grating, from said first grating to said second grating, and from said second grating back to said beamsplitter, said first and second beams propagating clockwise and counter-clockwise, respectively, along said optical path, said first and second gratings each introducing angular dispersion into each of said clockwise and counter-clockwise beams; and a detector disposed in said output beam path to receive said clockwise and counter-clockwise propagating beams after being combined by said beamsplitter, wherein said first and second gratings are configured such that angular dispersion introduced by said first and second gratings together is greater than the angular dispersion introduced by either the first grating or the second grating individually, and said angular dispersion for said clockwise beam is in an opposite direction as said angular dispersion for said counter-clockwise beam.