Interpolation equation for the calibration of infrared pyrometers

A new interpolation equation for the calibration of infrared pyrometers was derived by using the reference wavelength method. The errors associated with the new interpolation equation were calculated by comparing the temperature scale based on the interpolation equations with that determined by the fundamental method based on Planck's radiation law. To assess the usefulness of the new interpolation equation, the errors were compared with those associated with the interpolation equation previously used which was derived by the effective wavelength method. We find that the new interpolation equation can interpolate and extrapolate the temperature scale of an infrared pyrometer calibrated by the multiple-point-calibration method with small error over a wide temperature range. The equation is especially useful for the calibration of infrared pyrometers, when making measurements at low temperatures (< 600°C) with the response band in the long-wavelength infrared region.