Efficiency of Multispectral Pyrometer Technology in the Infrared Spectral Band According to Planck's Law on the Real Body in the Case of Oxidized Steels

This research is based on a theoretical analysis of thermal radiation, the fundamental laws of Planck and Kirchhoff, and multispectral processing methods using nonlinear models. Accurate high-temperature measurement is a major challenge in many scientific and industrial fields, including thermal processes, metallurgy, energy, and fundamental research. Planck’s law gives de relation between radiation, temperature ant wavelength. That low can be used to determine temperature by pyrometry method. Besides Planck’s law for the black body multiplied by the emissivity will gives the expression of the real body. Uncertainty in emissivity is the main source of error in conventional pyrometric measurements. In our case, the polynomial model of emissivity only goes up to the second order. To reduce the influence of emissivity and improve measurement reliability, several approaches have been developed, including monochromatic, bichromatic, and multispectral pyrometry based on Planck's law. The characteristics of chromatic luminance in the near and mid-infrared bands highlight the high potential of pyrometry for measuring high temperatures in complex environments. Compared to traditional approaches, this pyrometry technology offers greater robustness to variations in emissivity and environmental uncertainties. Luminance across the infrared spectral band and a temperature range provides improved linearity. This linearity highlights the strength of using infrared radiation for remote temperature sensing. The mid-infrared zone offers greater stability and a closer relationship between luminance, temperature, and wavelength in temperature detection for oxidized steel.