High-temperature dual-band thermal imaging by means of high-speed CMOS camera system

When measuring rapid temperature change as well as measuring high temperatures (>2000 K) commercial pyrometers reach the limits of their performance very quickly. Thus a novel type of high temperature measurement system using a high-speed camera as a two-color pyrometer is introduced. In addition to the high temporal resolution, ranging between 10 μs - 100 μs, the presented system also allows the determination of the radiation temperature distribution at a very high spatial resolution. The principle of operation including various image processing algorithms and filters is explained by means of a concrete example, where the surface temperature decay of a carbon electrode heated by an electric arc is measured. The measurement results yield a temperature of a hot spot on the contact surface of 3100 K which declines to approx. 1800 K within 105 ms. The spatial distribution of surface temperatures reveal local temperature variations on the contact. These variations might result from surface irregularities, such as protrusions or micro-peaks, due to inhomogeneous evaporation. An error analysis is given, for evaluating the potential accuracy inherent in practical temperature measurements.