Dispersion-matched compensation of polarization chromatic aberration in polarization-multiplexed AOTF imaging

Polarization multiplexing can increase the throughput of acousto-optic tunable filter (AOTF) spectral imagers, but wavelength-dependent angular separation between ordinary and extraordinary rays causes polarization chromatic aberration at the detector. We propose a passive dispersion-matched compensation method that suppresses this error before image formation. A quarter-wave plate converts the two linear polarization channels into opposite circular states, and a liquid-crystal polarization grating provides opposite Pancharatnam-Berry diffraction for angular redirection. In a 3.7-4.8 μm MWIR AOTF imager, a fixed 1200-μm-period LCPG reduces the relative o-/e-ray misregistration from 5.5 pixels to below 0.9 pixels while providing a 45-62% measured signal enhancement over single-polarization acquisition.