BABAR: Black Array of Broadband Absolute Radiometers for far infrared sensing
Christopher S. Yung, Nathan A. Tomlin, Cameron Straatsma, Joel Rutkowski, Erik Richard, Dave Harber, John H. Lehman, Michelle S. Stephens
Currently at NIST, there is an effort to develop a black array of broadband absolute radiometers (BABAR) for far infrared sensing. The linear array of radiometer elements is based on uncooled vanadium oxide (VOx) microbolometer pixel technology but with the addition of two elements: vertically aligned carbon nanotubes (VACNTs) and an electrical substitution heater. Traditional microbolometer pixels use a thermistor film as an absorber, which is placed a quarter wavelength above a reflector, typically limiting absorption to a narrow band from 8 15 µm. To extend the sensing range of the imaging array into the far infrared (20 100 µm), we are replacing the cavity with a single absorber of VACNTs. In addition, each pixel has an electrical substitution heater which can be used to determine equivalent incident optical power when the device is non- illuminated. This device forms the basis of an absolute radiometer, eliminating the need for an external reference (e.g. blackbody source).