TIME-SERIES AND TWO-DIMENSIONAL MEASUREMENT OF SURFACE TEMPERATURE BY FLUORESCENCE

摘要

This paper describes a high time resolution measurement of surface temperature by image processing using fluorescence near room temperature. The measurement of temperatures by fluorescence is nonintrusive, conceptually simple and it is easy to measure the two-dimensional distribution of the temperature. The components of the thermal imaging measurement system are shown in Figure A-1. In this system a fluorescent paste of particles was coated on a test surface and excited by short wave-length of a pulsed xenon lamp. The linearity between the fluorescence intensity and the temperature constitutes the measurement of surface temperature itself. The fluorescence intensity also depends on the excitation intensity and the concentration of fluorescent particles, then these parameter caused the measurement errors. In the present method we aimed to minimize these errors. The scattered intensity from fluorescent particles was simultaneously measured by the same camera as the reference for excitation intensity. Another error caused by the local concentration of fluorescent particles is also minimized by taking the reference of the concentration at any temperature. By an appropriate combination of fluorescent particles and excitation light, a three CCD color camera can be employed to measure the fluorescence (and confirming the excitation intensities by observing the wavelength sensitive to the CCD (B) sensor through a single receiving optics). Figure A-2 shows the luminous values of RGB channels for temperature. Depending on luminous wavelength, fluorescence is measured by the R channel, and scattered light is measured by the B channel. The system is simpler and easier for obtaining the coincidence between two real images than by two cameras system. Figure A-3 shows the measured result of the surface temperature compared with thermocouple data indicated in real scale. We clearly see the temperature gradient, and its temperature distribution is agrees with the thermocouple data. As a result, this system worked with an uncertainty band of ±2.6K in temperature ranging from 293K to 343K. This method can be applied to the heat transfer experiments with the so-described characteristic time and spatial scales.