Abstract
The Low-Background Infrared (LBIR) Facility at The National Institute of Standards and Technology (NIST) is interested in making ~1 pW absolute IR power measurements with 0.1% uncertainty. Given that there are no commercially available Absolute Cryogenic Radiometer (ACR) controllers that operate in this power regime, the LBIR Facility investigated the use of commercial off-the-shelf (COTS) electronics components, such as AC resistance bridges and tabletop voltmeters, to develop a research-grade ACR controller with an open architecture that could be configured and tuned to operate at lower power levels than commercial controllers. Last year at CALCON we presented the preliminary results of this project and showed that an electronics control system that was made of COTS components could be used for optical power measurements down to a noise floor of ~16 pW. This noise floor was the limit of both the commercial ACR control electronics and the optical receiver cavity that was used as the optical sensor for the testing. In order to improve the testing of the COTS ACR electronics, a new receiver cavity was made with ~30 times greater optical signal responsivity and a heater resistor with ~70 times greater resistance for improved electrical power measurement. In addition, this year LBIR has acquired the latest model commercial ACR control electronics which has a noise floor that is ~10 times lower. In this presentation we will discuss the low noise floor limit of the COTS ACR electronics when combined with the higher sensitivity receiver cavity and compare the power measurement accuracy of the COTS ACR electronics with those from the latest model commercial ACR electronics.
Control of a pW-Responsivity Absolute Cryogenic Radiometer by Commercial Off-the-Shelf Electronics
The Low-Background Infrared (LBIR) Facility at The National Institute of Standards and Technology (NIST) is interested in making ~1 pW absolute IR power measurements with 0.1% uncertainty. Given that there are no commercially available Absolute Cryogenic Radiometer (ACR) controllers that operate in this power regime, the LBIR Facility investigated the use of commercial off-the-shelf (COTS) electronics components, such as AC resistance bridges and tabletop voltmeters, to develop a research-grade ACR controller with an open architecture that could be configured and tuned to operate at lower power levels than commercial controllers. Last year at CALCON we presented the preliminary results of this project and showed that an electronics control system that was made of COTS components could be used for optical power measurements down to a noise floor of ~16 pW. This noise floor was the limit of both the commercial ACR control electronics and the optical receiver cavity that was used as the optical sensor for the testing. In order to improve the testing of the COTS ACR electronics, a new receiver cavity was made with ~30 times greater optical signal responsivity and a heater resistor with ~70 times greater resistance for improved electrical power measurement. In addition, this year LBIR has acquired the latest model commercial ACR control electronics which has a noise floor that is ~10 times lower. In this presentation we will discuss the low noise floor limit of the COTS ACR electronics when combined with the higher sensitivity receiver cavity and compare the power measurement accuracy of the COTS ACR electronics with those from the latest model commercial ACR electronics.