Short-Term Stability Measurements of a Germanium Plotodiode Radiometer

Published

October 1, 1998

Author(s)

G Andor, Bettye C. Johnson

Abstract

This paper describes a general stability measurement method for the short term stability, or repeatability, for radiometers using fixed-point blackbodies [BBs] as radiation sources. A germanium photodiode was used for the detector in the radiometer. The radiance during the melts and freezes was measured five times for a total of 14 h to 18 h with the radiometer for each BB. The undercooling of the freeze was used as a reference signal to establish a common temporal scale for the five data sets. The average of the standard deviations of the five measurements at each time t determined the standard uncertainty. This uncertainty includes the instability of the radiometer and the BB radiance as a function of time. Four BBs were measured with the radiometer. The repeatability of the output signal was found to be 0.006% to 0.002% in the optical power range from about 2 nW to 2mW. The repeatability determined using this method represents an upper limit of the short-term repeatability of the germanium radiometer.

Citation

Metrologia

Volume

35

Pub Type

Journals

Keywords

blackbody sources, germanium photodiode, optical radiation, radiometer repeatability, stability

Citation

Andor, G. and Johnson, B. (1998), Short-Term Stability Measurements of a Germanium Plotodiode Radiometer, Metrologia (Accessed October 8, 2025)