Construction and experimental verification of optimal expansion wavelength (OEW) inertia criterion based on three-channel wide-spectrum temperature measurement technology

Abstract

The optimal expansion wavelength (OEW) is a specific parameter that achieves the best approximation effect of the Taylor series on the temperature measurement integral equation. In the approximation of temperature measurement equations with different spectral emissivity, the OEW exhibits a high degree of stability, which is called the inertia of OEW to spectral emissivity. With the existence of this property, the approximation equation and temperature solution can be obtained by blackbody OEW in the case of unknown spectral emissivity. This serves as a fundamental basis for temperature measurement of targets with unknown spectral emissivity. To address the ambiguity in defining the inertia of OEW in this technique, a criterion for determining OEW inertia is proposed and verified by experiments. In this study, a parameter that quantitatively describes the approximation effects of the OEW is defined. By combining the discussion on the intersection of the approximation data and the reduced-channel signal under different approximation effects, an evaluation criterion for the OEW inertia is established through the definition of the confidence interval of the approximation effect. To macroscopically validate the correctness of the OEW inertia criterion, a simulation study is conducted to investigate the impact of the amplitude and FWHM of the spectral response function (SRF) on OEW inertia, based on this criterion. The correctness of the simulation results is confirmed through comparative experiments of temperature measurements on different SRF detectors, further demonstrating the correctness of the OEW inertia criterion.