Polarization pyrometry: an improvement to multi-wavelength optical pyrometry

We describe a new method that improves upon temperature measurement by optical pyrometry. The main uncertainty in the traditional pyrometry technique is the surface emissivity, which is generally unknown and hard to measure. A common approach to deal with this problem is to measure the thermal emission at multiple wavelengths - an approach called multi-wavelength pyrometry. However, this technique can still result in a level of uncertainty in the surface temperature that is unsatisfactory for scientific applications, such as a measurement of equation of state of warm dense matter. In contrast to the conventional multi-wavelength technique, in the polarization pyrometry approach described herein, p- and s-polarization components of thermal radiation at multiple-angles are used to deduce the temperature. This paper describes the concept and the results of an initial proof-of-principle static experiment with an electrically heated tungsten ribbon. It was found that in the same experiment, the accuracy of the polarization pyrometry measurement was substantially greater than that achieved using conventional multi-wavelength pyrometry.