JPS55144513A - Measuring method of emissivity - Google Patents

Abstract

PURPOSE:To accurately measure the emissivity of an object out of contact therewith, by detecting infrared rays of two wavelength regions emitted from the measured object and by determining such a point that temperatures for wavelengths corresponding to the quotients of the detection signals divided by various emissivities are equal to each other. CONSTITUTION:Infrared rays of lambda1, lambda2 in wavelength, which are emitted from an object 3, are detected by sensors 1, 2 through lenses 4, 5 and filters 6, 7. Detection signals P1, P2 from the sensors are passed through hold ciruits 10, 11 and divided by a provisional emissivity mu in calculation circuits 13, 14. The divided signals are applied to conversion circuits 15, 16 so that the signals are changed into temperature signals. When the value of the emissivity mu is swept from 1 to 0 by a sweep circuit 12, there is such a point mu that temperatures T1, T2 corresponding to the detection signals P1, P2 are equal to each other. The difference between the temperatures is detected by a discrimination circuit 18. When the temperature difference becomes zero, a display unit 19 is instructed to indicate the corresponding value mu. The emissivity of the object can thus be determined.