AOTF transmission shaping for spectral polarimetric imaging

Acousto-optic tunable filters (AOTF) enable high-performance imaging spectral photometry used in astronomy, remote sensing, biomedical imaging, and security. An essential feature of AOTFs is polarimetric capability owing to birefringence of crystals used in their design. A spectral polarimeter captures two orthogonal polarizations simultaneously. However, AOTF's two-dimensional transfer function in polarimetric mode is asymmetric. We demonstrate using chirped driving RF signals to obtain uniform transfer function for two orthogonally polarized Bragg images. This technique can be also used for adjusting the spectral transmission of an AOTF supporting up to 10-fold extension of the passband.