Optimization of Wavelength Selection for a Two-Color Pyrometer Based on the Flux Ratio and Planck's Law on Real Body

Le résumé fourni par la source

This article examines a methodical analysis for optimizing the wavelength selection used for the two channels of a bichromatic pyrometer. Temperature measurement via pyrometry relies on analyzing the radiation emitted by a body at various wavelengths, enabling non-contact thermal assessment. Several laws mathematically characterize this thermal radiation: Lambert’s law, which states that radiance is independent of the emission direction, and Planck’s law, which allows for the calculation of the body's radiation energy density. The bichromatic pyrometer utilizes distinct wavelengths; it consists of two separate spectral filter channels and two detectors with different spectral sensitivities, each followed by its own analog processing electronics. The two signals representing the thermal radiation undergo this analog processing before being combined through digital processing. A crucial step is selecting the wavelengths for the two spectral filters. Depending on the approach, calculations for a bichromatic pyrometer can be based either on the flux ratio combined with Wien’s approximation or on the flux ratio combined with Planck’s law, with each approach offering a different level of compensation for emissivity variations. In our case, the second method, that is to say the flux ratio using Planck's law will be used. This method applies Planck’s law to a real body by modeling emissivity as a second-degree polynomial. By varying the ratio value, we can calculate pairs of wavelengths based on their difference; this difference is then evaluated against relative errors to determine how to optimize the selected wavelengths. Optimizing wavelength selection in the bispectral system, by using two wavelengths simultaneously, improves the accuracy of temperature estimation and enables more reliable modeling of the materials' spectral behavior.

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