A division of aperture MWIR imaging polarimeter

Abstract

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.

Comparing a MWIR and LWIR polarimetric imaging for surface swimmer detection

“…Several polarimeter designs have been proposed to measure polarization simultaneously. [4] The division of aperture imaging polarimeter presented here, and shown in Figure 3 has a unique lens design which duplicates a single image formed by a standard objective onto four quadrants of a single FPA.. [5] Figure 4 shows an example of 4 images taken from the imaging polarimeter.…”

Progress in development of imaging polarimeter for Stokes parameter measurement

“…The architecture of a division of aperture polrimeter shows in Fig.6 [12] , it use a standard objective lens to form an image of the object onto the field stop. Then, a collimation optic forms an image of the objective lens aperture onto the 2*2 mini lens array so that the light from image formed by object lens is eventually divided and reimaged on the IRFPA separately in 0, 45, 90, 135 degrees.…”

2-Cam LWIR imaging Stokes polarimeter

“…Analyzing the data allows us to extract the extinction ratio of the polarizer in addition to the phases (θ T , θ R ) at each pixel. 11 The amplitude of the oscillations are related to the extinction ratio (ε) by,…”