Development of holmium oxide glass calibration system measured using mathematical modelling

Abstract

Holmium oxide glass filter has known to exhibit persistence absorption lines across the visible region. Due to these properties, a holmium oxide glass filter is used as a reference standard to calibrate the wavelength accuracy of a spectrophotometer. In this research, a system consists of a double-monochromator and a photomultiplier tube will be evaluated. Mathematical modelling is used to calculate the true value of the absorption lines of the holmium glass filter to compensate for the low optical resolution of the double-monochromator system. Measurement results are validated by comparison with the single-monochromator-order shorting filter system which has higher optical resolving power. Wavelength differences between double-monochromator and single-monochromator systems are better than 0.1% and within the expanded uncertainty of 0.32 nm. Therefore, the double-monochromator system is suitable to provide measurement traceability for the calibration of holmium oxide glass filters.