Simultaneous measurement of temperature, thermal diffusivity, thermal conductivity and spectral emissivity by photothermal radiometry

Abstract
The Laser Absorption Radiation Thermometer (LART) technique has been developed at the National Physical Laboratory (NPL) to measure temperature independently of target emissivity, surrounding background radiation or gaseous absorption. The technique is based on photothermal radiometry and utilises fibre optics in the latest instrument. Thermal properties can in principle be deduced from measurements of modulated (ac) and steady (dc) thermal radiations, in particular thermal diffusivity, thermal conductivity and spectral emissivity. The paper presents progress so far on "Multi LART" and initial measurements made of oxidised Inconel and platinum targets. The Multi LART instrument has great potential for meeting industrial needs for temperature and thermal properties measurements in challenging environments.