TECHNOLOGY AREA(S): Electronics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 5.4.c.(8) of the solicitation. OBJECTIVE: The U.S. Army has a need for advanced tracking capabilities in cluttered environments for high energy laser weapon systems. Current methodologies used include a passive wide field of view mid-wave infrared sensor. This solicitation is seeking innovative approaches to developing compact, lightweight polarimeters capable of measuring a full stokes vector. This is often referred to as a 3D polarimeter and includes horizontal and vertical linear polarization, linear polarization at +45 and -45 degrees, and right and left circular polarization. Mid-wave and long-wave infrared passive sensors are of interest. The system must be fast enough to track moving targets and detect a full Stokes vector at rates up to 200 Hz. Expected deliverables from a phase I effort include a design concept for implementing a snap shot polarimeter capable of detecting a full Stokes Vector with micropolarizers manufactured on a focal plane array. Phase II deliverables shall include a hardware prototype. DESCRIPTION: Polarization has been proven to enhance target detection in clutter with polarimeters. Use of the full Stokes vectors in polarimeters allows better identification in adverse weather conditions. This is difficult to implement because it requires horizontal and vertical linear polarization, linear polarization at +45 and -45 degrees, and right and left circular polarization for the same image. Tracking fast moving targets in tactical scenarios typically requires high frames rates (ex: 1kHz up to 4kHz). Polarimeters typically use single or multiple polarization filters in a rotation stage that collects different states of the same image before the image in the field of view of the sensor changes. Current rotating polarizers have proven insufficient for tracking fast moving targets in turbulent environments, where the scene is changing faster than the rate of the rotation stage. An alternative to using a rotation stage is to split the image into multiple cameras with a different polarization filters and wave retarders filtering light onto each camera. This method is costly and adds weight and size to the overall system. Additionally, the use of beam splitters and optical elements adds complexity to a rugged system. Some efforts have been made to implement polarization filters directly on a focal plane array. This approach reduces size, weight, and power required for a typical high speed rotation stage and allow for higher speed detection of all polarization states of a single image. Issues with this implementation include a loss in total image resolution by using multiple pixels to detect different polarization states of the same image location. This technology shows promise, but requires additional robustness and proven capability to push forward to tactical systems. PHASE I: Conduct research, analysis, and studies on the selected polarimeter architecture, develop measures of expected performance, and document results in a final report. Provide analysis supporting the method of polarimetry implementation and expected hardware performance. The phase I effort should include modeling and simulation results supporting performance claims. A preliminary concept and draft testing methodologies that can be used to demonstrate the polarimeter system proposed during the phase II effort shall also be produced. PHASE II: During Phase II, a passive MWIR or LWIR polarimeter concept design will be completed. Selected components will be developed and tested to help verify the design concept. A prototype polarimeter is expected to be tested at a minimum level. Parameters to be verified include polarization detection accuracy, overall rate of image collection and Stokes vector measurements. The necessary data processing techniques used for tracking shall be included in the phase II development. Methods to push data processing to desired operational rates shall be addressed, if not met. The extinction ratio, pixel cross talk, and total noise of the sensor shall be addressed. The data, reports, and tested hardware will be delivered to the government upon the completion of the phase II effort. PHASE III DUAL USE APPLICATIONS: There are many potential applications for high speed, lightweight polarimeters. Commercial and Military applications include tracking, remote sensing, weather radar, and astronomy. In phase III, a robust polarimeter capable of operating at high speeds shall be developed and field tested to prove target detection in clutter. Military funding for this phase III effort would be executed by the US Army Space and Missile Defense Technical Center as part of its Directed Energy research. REFERENCES: Huafeng Lianga, Jianjun Lai, Zhiping Zhoua, Li Lic, Design and fabricating of visible/infrared dual-band microfilter array , Proc. of SPIE Vol. 7135, 71350S, 2008 David L. Bowers, James K. Boger, L. David Wellems, Steve E. Ortega, Matthew P. Fetrow, John E. Hubbs, Wiley T. Black, Bradley M. Ratliff, J. Scott Tyo, Unpolarized calibration and nonuniformity correction for long-wave infrared microgrid imaging polarimeters , SPIE conference on Polarization: Measurement, Analysis, and Remote Sensing VII, April 2006 J. Scott Tyo, Dennis L. Goldstein, David B. Chenault, and Joseph A. Shaw, Review of passive imaging polarimetry for remote sensing applications , 1 August 2006, Vol. 45, No. 22, APPLIED OPTICS Viktor Gruev, Rob Perkins and Timothy York, Integrated High Resolution Division of Focal Plane Image Sensor with Aluminum Nanowire Polarization Filters , SPIE conference on Polarization: Measurement, Analysis, and Remote Sensing IX, 2010 Neal J. Brock, Bradley T. Kimbrough, James E. Millerd, A pixelated polarizer-based camera for instantaneous interferometric measurements , SPIE conference on Polarization Science and Remote Sensing V, 2011 J. Scott Tyo, Charles F. LaCasse, and Bradley M. Ratliff, Total elimination of sampling errors in polarization imagery obtained with integrated microgrid polarimeters , OPTICS LETTERS, Vol. 34, No. 20, October 15, 2009 KEYWORDS: passive tracking, polarimeter, polarization imaging, target detection in clutter TPOC-1: Amanda Black Phone: 256-955-5543 Email: amanda.m.black.civ@mail.mil TPOC-2: Jenny Niles Phone: 256-955-5484 Email: jenny.f.niles.civ@mail.mil
