Performance of microbolometer focal plane arrays under varying pressure

In this letter, we present a study of imaging using a 128 x 128-pixel microbolometer focal plane array (FPA) under varying pressure conditions from 10(-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 degrees 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.