Absolute calibration of streaked visible spectroscopy for pyrometry measurements on Z

Abstract

Summary form only given. The goal of streaked visible pyrometry experiments on Z is to determine the temperature of dynamic material samples using the Plank equation dL/dλ = e 2hc2/λ5 (ehc/λkT-1) (1). The spectral irradiance dL/dl describes the amount of power emitted per unit area per unit solid angle per unit wavelength. Ideally, an absolute calibration is used to convert the measured signal such as CCD counts or film exposure to units of spectral irradiance (W/mm2/steradian/nm). Relative calibration, where measurements at different wavelengths are proportional to radiance by the same scaling factor can be useful for determining a “color” temperature. However, even at lower temperatures a relative measurement does not constrain the temperature as accurately as an absolute measurement. At higher temperature where there is little difference in the spectral irradiance at visible wavelengths, a relative calibration fails to constrain temperature at all. We have been unable to find a broadband calibration source that is bright enough to adequately expose our streaked pyrometer in a single step. Instead, this paper describes a multistage process for absolute calibration, taking care to link each stage into a complete calibration with minimum errors.