Intensity-Dependent Infrared Blocking Filter for Source Exclusion

Physical Sciences Inc. proposes to develop an intensity-dependent infrared filter that will use the radiant intensity of the source (i.e. the sun) to locally control the infrared transmission of the filter. There currently exists an Air Force need for optical source exclusion to allow next-generation infrared camera technology to observe a large field of view (+/- 45 degrees, ~ 15% of the sky). While such systems will enable new tracking capabilities, the sun will often be within the field of view, leading to blooming on the focal plane array. PSIs filter will be placed at an intermediate focal plane and will be able to operate in two paradigms. The first will use the full spectrum of the suns energy to attenuate the IR transmission only where the image of the sun is formed, allowing the bright source to be dimmed without distorting or blocking the rest of the image field, and will not require an external power source The second will be sensitive to less bright objects, such as the moon, where feedback from the filter can determine which areas of the filter are turned on and off.