Abstract
Two teams at the National Institute of Standards and Technology (NIST) have been collaborating to develop a carbon nanotube radiometer (CNTR) for use in high accuracy cryogenic optical calibrations. This novel device employs an absorber made from a vertically aligned nanotube array (VANTA), which can exhibit nearly perfect absorption from visible wavelengths to the far-infrared. A molybdenum heater and VANTA thermistor, integrated with the absorber on the same silicon substrate, allow the detector to be operated in an electrical-substitution mode at a fixed temperature using a feedback control loop. All parts of the radiometer are fabricated using thin film techniques and silicon micro-machining, enabling the development of highly reproducible absolute cryogenic radiometers with precisely tailored properties. We discuss a version of the carbon nanotube radiometer designed with a thermal time constant near 1 ms, power noise floor near 1 pW, and absorber diameter of 3 mm.
Carbon Nanotube Radiometer for Cryogenic Calibrations
Two teams at the National Institute of Standards and Technology (NIST) have been collaborating to develop a carbon nanotube radiometer (CNTR) for use in high accuracy cryogenic optical calibrations. This novel device employs an absorber made from a vertically aligned nanotube array (VANTA), which can exhibit nearly perfect absorption from visible wavelengths to the far-infrared. A molybdenum heater and VANTA thermistor, integrated with the absorber on the same silicon substrate, allow the detector to be operated in an electrical-substitution mode at a fixed temperature using a feedback control loop. All parts of the radiometer are fabricated using thin film techniques and silicon micro-machining, enabling the development of highly reproducible absolute cryogenic radiometers with precisely tailored properties. We discuss a version of the carbon nanotube radiometer designed with a thermal time constant near 1 ms, power noise floor near 1 pW, and absorber diameter of 3 mm.