Patent ID: 6860634

Claim:
A method of temperature measurement for measuring a temperature of an object to be measured that is heated by a heating source in a multiplex-reflection environment, comprising: providing at least two radiation thermometers at a measurement part separated from the object to be measured; measuring a radiation rate of the object to be measured using said radiation thermometers; and calculating a temperature based on the radiation rate, wherein each of the radiation thermometers includes a rod that is embedded in the measurement part and can receive radiation from the object to be measured, each rod having the same diameter, and an optical fiber connected to each rod, the numerical apertures of the radiation thermometers being different; wherein the multiplex-reflection environment is formed between a surface of the measurement part facing the object to be measured and the object to be measured; and wherein calculating a temperature based on the radiation rate comprises determining a radiation rate ε of the object to be measured and the temperature of the object to be measured by a calculation that includes the following equations α=1−(1 −NA*N 1 ) N2(D1/D2) ε eff =(1−α)*ε+α*ε/{1 −F*r *(1−ε)} wherein D 1 represents the diameter of the rods of the radiation thermometers, NA represents the numerical aperture for each of the radiation thermometers, D 2 represents a distance between the object to be measured and the surface of the measurement part, r represents a reflectivity of the surface of the measurement part, F represents a view factor, α represents a multiplex reflection coefficient, ε eff represents an effective radiation rate of the object to be measured at each value of NA, and N 1 and N 2 are parameters.