Patent ID: 6488407
Filing Date: 2002-12-03
Classification: G01J

Abstract:
A radiation temperature measuring method that determines a temperature of a flat measuring surface of a measuring object on the basis of a measured radiation intensity obtained by using an optical reflector having a flat reflecting surface narrower than the measuring surface and disposed with the reflecting surface thereof facing the measuring surface, and an optical path extended through the optical reflector formed by a plurality of optical path forming members and having an exposed light-receiving plane surrounded by the reflecting surface, and by receiving radiation having undergone multiple reflection between the measuring surface and the reflecting surface through the light-receiving plane of the optical path forming members, said radiation temperature measuring method comprising the steps of:a) setting four combinations of measuring conditions (S1, d1), (S2, d2), (S1, d2), and (S2, d2), where S1 and S2 are the areas S of the reflecting surfaces, and d1 and d2 are the distances d between the reflecting surfaces and the measuring surface, and measuring ES1d1, ES2d1, ES1d2, and ES2d2, which are the radiation intensities E for the four combinations; b) for each of the combinations of measuring conditions, substituting the corresponding area S of said combination, and an area of a side surface of a cylindrical space between the reflecting surface and the measuring surface, said area being a product of the perimeter D of the reflecting surface and the corresponding distance d of said combination, and the measured radiation intensity E for said combination into an expression: E=(&egr;E0Ã·(1âˆ’R(1âˆ’&egr;)) )Ã—S+DÃ—dÃ—(EN1âˆ’EL1)+(EN2âˆ’EL2), where &egr; is an emissivity of the measuring surface, E0 is a blackbody radiation intensity at a temperature T, R is a reflectivity of the reflecting of the reflecting surface, (EN1âˆ’EL1) is a correction for correcting an error due to noise entering and leaking from the cylindrical space between the reflecting surface and the measuring surface, and (EN2âˆ’EL2) is a correction for correcting an error due to noise entering an leaking from the space between the reflector and the optical path, to calculate (EN2âˆ’EL2) for each of the four combinations;c) substituting calculated (EN2âˆ’EL2) and any two of the radiation intensities ES1d1, ES2d1, ES1d2, and ES2d2 obtained in the step (a) into the expression, thereby determining EN1âˆ’EL1; d) correcting the measured radiation intensity on the basis of the expression into which (EN1âˆ’EL1) and (EN2âˆ’EL2) are substituted; e) calculating the emissivity of the measuring surface on the basis of a measured radiation intensity measured with the reflector removed and the corrected measured radiation intensity corrected in step d); and f) determining the temperature of the measuring surface on the basis of the emissivity of the measuring surface and the measured radiation intensity measured with the reflector removed.