Selection of Spectral Variables and Improvement of the Accuracy of Calibration of Temperature by Projection onto Latent Structures Using the Fluorescence Spectra of Yb3+:CaF2

The efficiency of interval methods for selecting variables and the divisive method of interval optimization by a genetic algorithm is considered with the purpose to increase the accuracy of temperature calibration by projection onto latent structures. The fluorescence spectra of Yb³⁺:CaF₂ recorded in the 880–1120 nm band with a resolution of approximately 0.2 nm in the temperature range from 66 to 150°C in 2°C increments are used as an example. The best result for the root-mean-square error of temperature prediction in the test sample (0.45°C) was obtained by interval projection onto latent structures by a combination of moving windows. The use of methods for selecting spectral variables improved more than two times the accuracy of temperature calibration.