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Incandescent lamp-based facility for measuring the long-term radiometric stability of spectrographs



Ping-Shine Shaw, John T. Woodward IV, B. Carol Johnson, Steven W. Brown, Howard W. Yoon


The stability of a spectrograph is a one of the most important characteristics affecting the spectrograph's radiometric performance. For many applications such as absolute irradiance measurement for laboratories and remote sensing, the stability of a spectrograph is a primary factor in the overall measurement uncertainty and therefore is the major criterion for the suitability of the spectrograph as an optical-scale transfer standard. Here, we report a facility built for testing the long-term radiometric stability of spectrographs. The facility uses incandescent irradiance standard lamps of the National Institute of Standards and Technology (NIST) as light sources. To ensure highest stability of these lamps during spectrograph tests, parameters like lamp current, lamp voltage, and signal from an independent filter radiometer were continuously recorded to monitor any possible instability caused by such effect as lamp ageing. Using these lamps, several commercial spectrographs, with spectral coverage from the UV to short-wave infrared (SWIR), were monitored over a period of several months during which the lamp irradiance was stable to better than 0.02%. The spectrographs tested show good stability in general ranging from 0.02% to 0.1% with no discernable long-term drifts. In addition, we also measured the response variation of some of those spectrographs before and after they were sent to remote field locations and subjected to adverse environmental conditions. In this case, a larger response variation of up to 0.5% was observed. We discuss the performance of the facility and the implications for using these spectrographs for several NIST's remote sensing projects as radiometric transfer standards based on these stability measurements.
Applied Optics


Spectrograph, Radiometry, Stability


Shaw, P. , Woodward IV, J. , Johnson, B. , Brown, S. and Yoon, H. (2021), Incandescent lamp-based facility for measuring the long-term radiometric stability of spectrographs, Applied Optics, [online], (Accessed April 17, 2024)
Created December 10, 2021, Updated April 18, 2022