Low-cost. Lightweight, Mid-Wave InfraRed (MWIR) Sensors

"The successful demonstration of staring lead salt based focal plane technology has been impeded by one, the inability of previously existing ROIC technology to integrate the substantial dark currents associated with near foom temperature operation ofphotoconductive detectors and two, the limitations of surface morphology of lead salt substrate materials. To address these technical challenges, we have developed an ROIC which operates very well with the high dark current of these devices and havedeveloped a concept for detector pixel integration called balanced differential input (BDI). The BDI concept effectively nulls out a significant portion of the dark current before the ROIC input stage. With the develop[ment of the BDI device we havesuccessfully addressed the issue of ROIC dynamic rannge. The BDI detector is comprised of two elements within a single unit cell. One cell is, in effect, "blind" and the other an active cell. the biasing scheme allows for equal and opposite darkcurrents. By combiming the currents at the input circuit, the integrating capacitor will need to store the difference between the light and dark currents. Besides the advantage of significantly lowering the milirtary system cost for MWIR sensors thecommercial benefits are substantial. The concept should reduuce, for example, the cost of a MWIR camera for firefighter protection by a factor of two to under $10K. The potential for spectroscopy and remote s