Ultra-compact snapshot imaging fourier transform spectrometer
AssigneeArizona Board of Regents on Behalf of the University of Arizona
InventorMichael W. Kudenov
Life of this patent
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Abstract
Snapshot imaging Fourier transform spectrometers include a lens array that produces sub-images that are directed through a birefringent interferometer in orthogonal polarization eigenstates that acquire an optical path difference. Interference patterns based on this OPD can be Fourier transformed to obtain a spectral image. In some examples, polarizing gratings provide a spatial heterodyne frequency and offset the spectra.
Claims16
An interferometer, comprising, from object-wise to image-wise along an axis:
- a lens array that produces a plurality of sub-images of an object based on associated sub-image light fluxes;
- a polarizing grating situated to produce an interference pattern in the sub-image light fluxes having a wavelength independent spatial frequency that is associated with a period of the polarizing grating;
- a birefringent prism that produces a spatially varying optical path difference (OPD) between orthogonal polarization states associated with the sub-image light fluxes;
- a polarization analyzer situated to project at least a portion of orthogonal polarization states of the sub-image light fluxes to a common polarization state;
- an array detector situated to receive the projected sub-image light fluxes;
- and
- a processor coupled to the array detector that produces a spectral image based on calculations using portions of the sub-image light fluxes associated with the wavelength independent spatial frequency.
A spectral imaging method, comprising:
- directing a plurality of sub-image light fluxes associated with an object to a birefringent prism so as to produce optical path differences between orthogonal states of polarization of the sub-image light fluxes;
- transmitting the sub-image light fluxes with the optical path differences to a polarization analyzer;
- processing the sub-image light fluxes with at least one polarization grating to produce a wavelength-independent spatial frequency in sub-image light flux interference patterns;
- recording intensity patterns based on the polarization analyzed sub-image light fluxes;
- and
- processing the recorded intensity patterns so as to produce a spectral image of the object based on calculations using the wavelength independent spatial frequency.
A spectral imaging apparatus, comprising, along an axis from an object:
- a lens array that produces a plurality of sub-images of an object associated with sub-image light fluxes;
- a polarization generator that polarizes the sub-image light fluxes;
- a birefringent prism pair situated to receive the polarized sub-image light fluxes such that the sub-image light fluxes propagate in the birefringent prism pair in at least two eigenpolarizations;
- a quarter wave retarder situated to receive the sub-image light fluxes from the birefringent pair and produce corresponding circularly polarized light fluxes;
- a first polarization grating situated to receive the circularly polarized light fluxes and produce corresponding diffracted light fluxes;
- an array detector configured to record the diffracted light fluxes;
- and
- a processor that produces a spectral image based on a Fourier transform of the diffracted light fluxes such that the spectral image is calculated based on detected portions of the recorded diffracted light fluxes associated with a spatial heterodyne frequency based on a period of the polarizing grating.
Dependencies are inferred from the claim text.