Performance of microbolometer focal plane arrays under varying pressure

In this letter, we present a study of imaging using a 128/spl times/128-pixel microbolometer focal plane array (FPA) under varying pressure conditions from 10/sup -5/ torr to the ambient. We have employed bulk micromachining in the fabrication of FPA to reduce the thermal conduction through the air-gap between the membrane and the substrate of the microbolometers. It was found that an image of a soldering iron (200/spl deg/C) was clearly visible even at the ambient pressure. However, at ambient pressure, the increased in thermal conductance resulted in a reduction of contrast of the image compared to the ones obtained at low pressure. The results suggest the possibility of operation of uncooled FPA´s under ambient pressure by proper design of the microbolometer structure.