Patent ID: 6840669

Claim:
A method for measuring the temperature of an object or environment with a photoluminescent probe, comprising the steps of: a) providing a probe in thermal communication with said object or environment, said probe including a photoluminescent material so characterized that, when illuminated at any temperature within the temperature range of application of the method with a first excitation light of intensity P 1 and pre-selected wavelength or wavelengths λ 1 , it emits a first luminescence light of intensity I 1 , and when illuminated with a second excitation light of intensity P T and pre-selected wavelength or wavelengths λ v , it emits a second luminescence light of intensity I T so related to the luminescence intensity I 1 that the ratio (I T .P 1 /I 1 .P T ) varies substantially in a known manner with varying temperature independently of any temperature-dependent changes in the luminescence efficiency of said photoluminescent material; b) illuminating said material with said first excitation light of said wavelength or wavelengths λ 1 and intensity P 1 , thereby generating a first luminescence light emitted by the probe with said intensity I 1 ; c) directing a fraction of said intensity I 1 of said first luminescence light to photodetector means; d) illuminating said material, subsequently to its illumination with said first excitation light, with said second excitation light of an intensity P T and wavelength or wavelengths λ v , thereby generating a second luminescence light emitted by the probe having an intensity I T ; e) directing a fraction of said intensity I T of said second luminescence light to photodetector means; and f) measuring the relative intensities of the luminescence lights generated by said first and said second excitation lights received by said photodetector means, said relative intensities being an indicator of the temperature being measured.