Short wave infrared polarimeter
A short wave infrared polarimeter comprising a pixelated polarizer array and an Indium-Gallium-Arsenide (“InGaAs”) focal plane array. The short wave infrared polarimeter optionally includes a micro-lens array and/or an aperture layer.
1. A short wave infrared polarimeter comprising: a PPA and an InGaAs FPA of equivalent pitches, the PPA comprising a first substrate and pixels for polarizing energy from a source, each said PPA pixel comprising a wire grid comprising wires laid directly on the first substrate and the InGaAs FPA comprising a second substrate and pixels comprising active areas, the PPA affixed to and parallel with the InGaAs FPA, and the PPA and the InGaAs FPA aligned so that the PPA pixels correspond one-to-one to the InGaAs FPA pixels and each of the PPA pixels transmits the polarized energy to one of the InGaAs FPA pixels, and further comprising a micro-lens array comprising a third substrate and pixels, said micro-lens array being positioned securely on a side of the PPA opposite the InGaAs FPA, said pixels of said micro-lens array having a dimension which is twice a corresponding dimension of the PPA pixels.
2. The short wave infrared polarimeter as in claim 1 , wherein the PPA pixels are arranged in super-pixels, each said super-pixel comprising a 2×2 array of the PPA pixels in which the wires of each of the PPA pixels are positioned in one of four different polarization states.
3. The short wave infrared polarimeter as in claim 1 , further comprising an aperture layer abutting the PPA, said aperture layer comprising a fourth substrate and an opaque mask, said opaque mask comprising circular openings comprising a diameter, said circular openings corresponding one-to-one to the PPA pixels, such that the energy from the source may pass through the circular openings to the PPA pixels.
4. The shortwave infrared polarimeter as in claim 3 , wherein the diameter of the circular openings is within a range of 50-100% of the pitch of the PPA pixels.
5. The shortwave infrared polarimeter as in claim 1 , wherein the PPA pixels produce a plane of polarization and transmission of a range of approximately 60% to 99% of the polarized energy to the InGaAs FPA pixels whose transmission axis is aligned with the plane of polarization.
6. The shortwave infrared polarimeter as in claim 1 , wherein the polarized energy has a desired polarization state and an undesired polarization state, and there is an extinction ratio of the desired polarization state to the undesired polarization state.
7. The shortwave infrared polarimeter as in claim 6 , wherein the extinction ratio is at least 10:1.
8. The shortwave infrared polarimeter as in claim 6 , wherein the extinction ratio is approximately 1000:1.
9. The shortwave infrared polarimeter as in claim 6 , wherein the extinction ratio is approximately 5000:1.
10. A shortwave infrared polarimeter comprising: a PPA and an InGaAs FPA of equivalent pitches, the PPA comprising a first substrate and pixels for polarizing energy from a source and said polarized energy having an extinction ratio of at least 100:1 of a desired polarization state to an undesired polarization state, each said PPA pixel comprising a wire grid comprising wires laid directly on the first substrate and the InGaAs FPA comprising a second substrate and pixels comprising active areas, the PPA affixed to and parallel with the InGaAs FPA, and the PPA and the InGaAs FPA aligned so that the PPA pixels correspond one-to-one to the InGaAs FPA pixels and each of the PPA pixels transmits at least 95% of the polarized energy to one of the InGaAs FPA pixels, and further comprising a micro-lens array comprising a third substrate and pixels, said micro-lens array being positioned securely on a side of the PPA opposite the InGaAs FPA, said pixels of said micro-lens array having a dimension which is twice a corresponding dimension of the PPA pixels.