Abstract
The paper presents an apparatus to measure surface temperature distribution of liquid metals during fusion processes. The apparatus is based on dual wavelength radiation thermometry and is designed to measure temperature from 1500 to 3000 K. The pyrometer is based on standard optical parts and industrial CCD cameras. Uncertainties are analysed on the base of the radiometric equations. To insure relative precision in the measurement, a calibration procedure is conducted on tungsten ribbon with known emissivity in the temperature range. This procedure is also used to discuss the influence of wavelength couples. To conclude, experimental measurements on pure laser melted materials are conducted to assess the validity of the apparatus and methodology.