The problem ofmine and minefield detection continues to provide a significant challenge to sensor systems. Although the various sensor technologies (infrared, ground penetrating radar, etc.) may excel in certain situations there does not exist a single sensor technology that can adequately detect mines in all conditions such as time of day, weather, buried or surface laid, etc. A truly robust mine detection system will likely require the fusion of data from multiple sensor technologies. The performance of these systems, however, will ultimately depend on the performance ofthe individual sensors.Infrared (IR) polarimetry is a new and innovative sensor technology that adds substantial capabilities to the detection of mines. JR polarimetry improves on basic JR imaging by providing improved spatial resolution ofthe target, an inherent ability to suppress clutter, and the capability for zero iT imaging. Nichols Research Corporation (Nichols) is currently evaluating the effectiveness of JR polarization for mine detection. This study is partially funded by the U.S. Army Night Vision & Electronic Sensors Directorate (NVESD). The goal of the study is to demonstrate, through phenomenology studies and limited field trials, that JR polarization outperforms conventional JR imaging in the mine detection arena.
This paper describes two sensors built on existing Nichols polarimetric sensor designs that provide Stokes four-vector polarimetric data on static targets. The midwave infrared (MWIR) sensor uses a Raytheon-Amber AE-173 indium antimonide (InSb) 256x256 focal plane array to provide data in the 3-5 micron waveband. The long-wave infrared (LWIR) sensor uses a Raytheon-Amber AE-173 mercury cadmium telluride (MCT) 256x256 focal plane array to provide data in the 8-10 micron waveband. To the extent possible, these sensors have been designed to use the same mechanical, optical, and electronics hardware.Each sensor uses a custom closed-cycle dewar, which contains the focal plane and an optics package, maintained at a constant temperature. The optics package contains a motorized eight-position filter wheel, a linear polarizer, and a motorized rotating % h waveplate. A warm lOOmm F/#2 refractive telescope is external to the dewar. A customized set of electronics is used to control the sensor and acquire and process the polarimetric image data in near real-time.
The design of a two-color two-spot laser velocimeter based on an argon laser and using backscattered light is presented. The prism assembly used in splitting the laser's output beam into 514.5- and 488.0-nm beams, also allows for the rotation of the two spots about a common center, allowing two components of a flow to be measured. The system was tested at ranges of 50, 100, and 150 m, and the results of these tests are presented.
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