Proposal of quantitative temperature measurement using two-color technique combined with several infrared radiometers having different detection wavelength bands

Abstract

Infrared thermography has been widely used to visualize a two-dimensional temperature field for various engineering applications. However, in general, conventional infrared thermography cannot directly be applied to quantitative temperature measurement on glossy metal surfaces under near-ambient conditions, because of the severe influ- ence of the reflected energy incident from the surroundings on the mea- surement. When it is necessary to measure the temperature quantita- tively, an appropriate calibration involving complicated procedures must be performed. In this paper, therefore, a new technique of measuring temperature is proposed for near-ambient conditions, by combining si- multaneously several infrared radiometers having different detection wavelength bands to enable a two-color technique, which does not re- quire any temperature calibrations. The sensors concerned have a se- lective wavelength band of several micrometers in width in the range of 2 to 13 mm. The applicability of the method, including a series of proposed equations, has been confirmed by an investigation; the numerical simu- lation presented merely allows a parametric study of how the result var- ies for different values of emissivity corresponding to a pair of infrared radiometers. An experimental investigation is also performed to estimate or correct the measurement error pertaining to the present technique. This technique has the feature that a two-dimensional temperature field can be evaluated quantitatively, nondestructively, and simultaneously at each picture element without presuming any emissivity and reflectivity, even though the object has a complicated shape; so that it may be useful in various medical or engineering applications. © 2001 Society of Photo-