In the past, many spaceborne, Earth viewing radiometers have had a fairly narrow optical field-of-view (FoV) and are scanned in the cross-track direction to provide the required coverage. These (point) scanners swing delicate optics and lack a full instantaneous cross-track coverage. To get around these undesirable issues, the cross-track direction can be optically a wide FoV telescope utilizing freeform optics [Phenis et al., Proc. of SPIE, 12078(12078J), 2021] along with a corresponding focal plane array (FPA). However, there are some unintended and undesirable consequences of wide FoV telescopes particularly when there is a significant lack of symmetry due, in part, to off-axis viewing. One of these consequences is a polarization bias imparted on the light due to the optics as it progresses along the optical chain. Here we develop the polarimetric radiometric uncertainty and a polarimetric error equivalent radiance which can be used in the optical design and radiometric error budget for imaging radiometers.
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