Patent attributes
Systems and methods are disclosed for a modified Sagnac interferometer having a plurality of gratings that can be reflective or transmissive. The gratings allow measurement of wavelength spectra in counter-circulating beams of the interferometer. In one embodiment, diffraction geometries at each pair of neighboring gratings are configured so that diffractive and angular contributions reinforce each other at the second of the pair of gratings. In one embodiment, diffraction geometries at the gratings are configured so that the exiting beams of the interferometer satisfy the crossing condition wherein the exiting beams are on the opposite sides of a reference beam axis for a design wavelength input beam. Also disclosed are techniques for restoring the reinforcement and/or crossing conditions when these conditions are not otherwise met.
