Reflection errors and uncertainties for dual and multiwavelength pyrometers
Reflection errors and lack of knowledge of surface emissivities are the largest limitations to accurate temperature measurements in many industrial applications of radiation thermometry. Dual and multiwavelength pyrometers are often used as a means of compensating for unknown or varying emissivity, but the effects that reflections have on these measurements have not received much attention. A generalised reflection model is presented from which the errors and uncertainties for dual and multiwavelength pyrometers are analysed. A method for compensating for the reflection error with a dual-wavelength pyrometer is developed, but it is shown that the uncertainties are larger than would be encountered for a single-wavelength pyrometer. The errors and uncertainties for multiwavelength pyrometers are shown to be so large as to make their use impracticable.