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.

An imaging polarimeter measures the polarization content of an image as well as the intensity and/or color. Imaging polarimeters can be broadly grouped into those which operate by measuring multiple polarization images simultaneously (Simultaneous Imaging Polarimeter) and those which measure a number of images sequentially in time (Sequential Imaging Polarimeter)

The division of aperture imaging polarimeter presented here has a unique lens design which duplicates a single image formed by a standard objective onto four quadrants of a single FPA

DOA Imaging Polarimeter Design
This figure shows the concept design for the Division of Aperture Imaging Polarimeter. A standard Camera objective lens is used to form an image of the object onto the field stop. The field-stop and relay optics are contained inside of a vacuum Dewar operating at 77k. The collimation optic forms an image of the Objective lens aperture onto the mini-lens array such that the light incident on the objective lens is evenly divided across the four mini-lens elements. Each mini-lens elements forms an image of the object onto the FPA. A polarizer is placed after each mini-lens to measure a different polarization state across the object. For this polarimeter design a set of four linear polarizers are used at orientations 0, 45, 90 and 135 degrees. Alternatively, other polarization elements can be used to measure circular polarization states as well. For our purposes measuring, linear polarization states is sufficient.