A new method for spectral irradiance and radiance responsivity calibrations using kilohertz pulsed tunable optical parametric oscillators

摘要

Continuous-wave (CW) tunable lasers have been used for detector calibrations, especially for spectral irradiance and radiance responsivity, for many years at the National Institute of Standards and Technology (NIST) and other national metrology institutes. These CW tunable lasers, however, are expensive and difficult to automate. To address these issues, we developed a new method for spectral irradiance and radiance responsivity calibrations using relatively low cost, fully automated kilohertz pulsed tunable optical parametric oscillators (OPOs). The new method is based on measurements of the total energy of a pulsed OPO train using two synchronized current integrators (also called charge amplifiers) to measure the total integrated electric charges from a test detector and a standard detector, respectively. The absolute expanded uncertainty of this method is estimated to be 0.05percent (with a coverage factor of k velence 2) for spectral irradiance responsivity calibrations, and the dominant uncertainty contribution is from the reference trap detector.