Primary realization of a spectral irradiance scale employing monochromator-based cryogenic radiometry between 200 nm and 20 µm

Abstract

Here we report on an alternative approach for making spectral irradiance measurements of radiation sources traceable, employing our monochromator-based absolute cryogenic radiometer (ACR) facility to its full extent. The method makes use of the continuously tunable absolute radiant flux emerging from the ACR facility to characterize and calibrate the spectral irradiance responsivity of a second adjacent double-monochromator system. This system will be part of a new facility at NMi-VSL, called SIR, that will be used to measure spectral irradiance distributions of radiation sources from the ultraviolet to the far infrared. Following this traceability route, a fully characterized high-temperature Planckian radiator is not needed. Proof-of-principle measurements in the visible part of the spectrum show very encouraging results. Although the new facility is under construction, the theoretical background and a schematic description will be presented in this paper.