Extremely broadband calibrated bolometers and microbolometer arrays for Earth radiation budget measurements
Michelle Stephens, Chris Yung, Nathan Tomlin, Dave Harber, Cameron Straatsma, Atasi Dan, Erica Freire Antunes, Peter Pilewskie, Odele Coddington, John H. Lehman
The Earth radiation budget, a 40-year data record of the balance between solar radiation reaching the Earth and the amount absorbed, reflected, and emitted from the Earth, is a key climate record for determining whether the Earth is warming or cooling. The need for accurate and cost-effective space-based measurements is driving the technology development of broadband bolometers and linear microbolometer arrays. We describe the fabrication and performance of microfabricated bolometers and 1 x 32 linear microbolometer arrays developed for this purpose. To accurately measure the total outgoing radiation from 0.3 to over 100 m, consisting of reflected shortwave solar radiation and emitted longwave thermal radiation, a vertically aligned carbon nanotube thermal absorber is incorporated with an electrical substitution heater that provides on-board calibration capabilities. A membrane heat link is used to maximize response time while minimizing noise and the inequivalence between thermal and optical heating. The devices operate at room temperature with noise floors at the nW/√Hz or lower at the measurement frequency of 7 Hz. Response times below 10 ms have been demonstrated in closed-loop operation using the electrical heater. Thin film Pt thermistors measure the change in microbolometer temperature. The deposition process of the thin film thermistors has been optimized to maximize the temperature coefficient of resistance, which is key to meeting the demanding signal-to-noise requirement of this application.
SPIE Conference on Infrared Sensors, Devices, and Applications XII
, Yung, C.
, Tomlin, N.
, Harber, D.
, Straatsma, C.
, Dan, A.
, Freire Antunes, E.
, Pilewskie, P.
, Coddington, O.
and Lehman, J.
Extremely broadband calibrated bolometers and microbolometer arrays for Earth radiation budget measurements, SPIE Conference on Infrared Sensors, Devices, and Applications XII , San Diego, CA, US, [online], https://doi.org/10.1117/12.2633044, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935259
(Accessed December 11, 2023)