Capturing spectral information from object and scene motion with polarization interferometry

A new method is introduced to obtain spectral information from object and scene motion, applicable to both spectral flow cytometry and hyperspectral imaging. Objects and scenes in motion are imaged onto a polarization interferometer consisting of a calcite Wollaston prism between parallel polarizers, with polarization axes at 45 with respect to the optical axes of the Wollaston prism. The polarization interferometer is placed in a conjugate focal plane of a flow cytometer detector, and due to the position-dependent optical path delay of the interferometer, interferograms are generated by particle flow. Fourier-transforming the interferograms with respect to time yields the optical spectrum of each particle. The polarization interferometer is also placed in front of a CMOS imaging array, and translation of the combined system with respect to a scene yields the interferogram of each scene point. A hyperspectral image of the scene is recovered by Fourier-transformation of these interferograms. The above two experiments demonstrate a means for obtaining spectral information from point particles and extended scenes that requires adding only a Wollaston prism and polarizing filters to existing optical systems. The method has applicability to situations where linear motion is already present, including flow cytometers, conveyor belt systems, fixed-wing aircraft, and satellites.