An optical system for use with a flight vehicle subject to aero-thermal heating, said optical system comprising: an optical window (12, 36, 52) having interior and exterior surfaces with a curvature with respect to a central axis, said optical window configured such that incident radiation from a target passes through both said interior and exterior surfaces each of which induces a P-polarization to the incident target radiation within a plane of incidence, said optical window configured to self-emit radiation that passes only through said interior surface which induces a P-polarization to the self-emitted radiation within the plane of incidence, said self-emitted radiation overlapping the spectrum of the target radiation; focusing optics comprising an entrance pupil offset from the central axis to look through an off-axis segment (64, 152, 206, 208) of the optical window, said focusing optics configured to route incident radiation along an optical path and focus the incident radiation at a focal plane; a detector (72, 116) at or near the focal plane configured to sense incident radiation; a polarizer (74, 117, 118, 150, 200,402,404) positioned in the optical path between the optical window and the detector, said polarizer comprising at least one filter pixel that imparts a linear polarization of a certain angular value to filter the incident radiation as a function of the polarization of the incident radiation; and a mechanism configured to align said at least one filter pixel to the P-polarization within the plane of incidence, said mechanism comprising: an outer gimbal configured to rotate about a first rotation axis; and an inner gimbal mounted on the outer gimbal, said inner gimbal configured to rotate the entrance pupil about a second rotation axis perpendicular or skew to the first rotation axis. an optical window (12, 36, 52) having interior and exterior surfaces with a curvature with respect to a central axis, said optical window configured such that incident radiation from a target passes through both said interior and exterior surfaces each of which induces a P-polarization to the incident target radiation within a plane of incidence, said optical window configured to self-emit radiation that passes only through said interior surface which induces a P-polarization to the self-emitted radiation within the plane of incidence, said self-emitted radiation overlapping the spectrum of the target radiation; focusing optics comprising an entrance pupil offset from the central axis to look through an off-axis segment (64, 152, 206, 208) of the optical window, said focusing optics configured to route incident radiation along an optical path and focus the incident radiation at a focal plane; a detector (72, 116) at or near the focal plane configured to sense incident radiation; a polarizer (74, 117, 118, 150, 200,402,404) positioned in the optical path between the optical window and the detector, said polarizer comprising at least one filter pixel that imparts a linear polarization of a certain angular value to filter the incident radiation as a function of the polarization of the incident radiation; and a mechanism configured to align said at least one filter pixel to the P-polarization within the plane of incidence, said mechanism comprising: an outer gimbal configured to rotate about a first rotation axis; and an inner gimbal mounted on the outer gimbal, said inner gimbal configured to rotate the entrance pupil about a second rotation axis perpendicular or skew to the first rotation axis. an outer gimbal configured to rotate about a first rotation axis; and an inner gimbal mounted on the outer gimbal, said inner gimbal configured to rotate the entrance pupil about a second rotation axis perpendicular or skew to the first rotation axis.