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A method for the correction of systematic errors generated by large orientational and retardance errors in the polarization optics in the dual rotating retarder polarimeter is presented. Small orientational and retardance errors (< 1°) can lead to large errors in the measured Mueller matrix (> 10% in some matrix elements). We incorporate correction terms for large orientation and retardance errors into the dual rotating retarder data reduction algorithm. Using these data reduction algorithms and a calibration step, the associated systematic errors are calculated and removed from the measured Mueller matrix. This procedure is especially useful for spectral and multi-wavelength systems in which the retardance and often the orientation of the retarders are wavelength dependent. The equations, the procedure to calculate the orientations of the polarization elements and the retardances of the retardation elements, and the method to correct for any errors are presented here. The effect of these errors on the calculated Mueller matrix elements and their correction is shown analytically and through experimental data taken on an infrared spectropolarimeter.

Imaging polarimetry has the potential to be a key sensor technology in a number of target detection applications. Imaging polarimeters measure the polarization state of light emitted from and/or reflected from scenes. The light is polarized because of the geometry, roughness and material properties of the objects embedded in the scene. This added information enhances conventional intensity and color imagery, potentially surpassing its performance in low contrast situations.In this paper, we describe a divided aperture MWIR imaging polarimeter which acquires multiple polarization images simultaneously. At the heart of the polarimeter is a relay lens set that produces four identical images on a single focal plane array from a single aperture. Each of the four images measures a different orientation of linear polarization, 0, 45, 90 and 135 degrees. The relay lens set operates inside of a pour fill Dewar of a InSb MWIR camera. The design and calibration method for the polarimeter are given along with example data sets taken from the air over Huntsville, AL.

The field-of-view dependence of polarizing beam-splitter cubes has been studied to characterize their behavior in imaging systems such as optical computers and optical correlators and in other applications that involve noncollimated light. Significant polarization aberration is present in polarizing beamsplitter cubes for two reasons: (1) the s- and p-component orientations, which define the polarizing axes, at the beam-splitting interface vary with the direction of propagation, and (2) the performance of the coating is a function of the angle of incidence. We describe the polarization aberration of a polarizing beam-splitter cube in terms of its diattenuation (polarizing efficiency). We use an imaging polarimeter to measure six figures of merit for three polarizing beam-splitter cubes demonstrating typical polarization aberrations. Finally, we derive the Mueller matrix for a polarizing beam-splitter cube in terms of the s and p transmittance and reflectance and the phase retardances, the parameters generally calculated with thin-film analysis programs.

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