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Tungsten strip lamps are calibrated at specific wavelengths. The calibration at one wavelength can be corrected to make it valid at another wavelength λ for calibrating a radiation thermometer that operates at λ. The correction can be obtained by a calculation based on either Wien’s or Planck’s radiation law with the knowledge of the spectral emissivity &Vegr; of the lamp filament and the spectral transmittance τ of the lamp window. Using published measurements of &Vegr; for tungsten and our measurement of τ for the window of a high-stability tungsten strip lamp, we develop analytical expressions for &Vegr; as a function of wavelength and temperature and for τ as a function of wavelength. These allow accurate calculations of the spectral dependence of the radiance temperature of such a lamp, from which the appropriate corrections can be made. Results are presented. [ABSTRACT FROM AUTHOR]

Blackbody simulators in the form of heated cavity radiators are widely used to calibrate IR radiation thermometers. The values of the local effective emissivities along the internal surface of an isothermal cavity decrease from the rear towards the aperture; the integrated value is always smaller than unity and is different for different calibration configurations. A simulator for which all of the local effective emissivities, and so also the integrated values, have the same value would be convenient for calibration purposes. We show that this can be simply achieved, in principle, by arranging for the intrinsic emissivity of the cavity surface to vary in such a way as to compensate for the change in effective emissivity. The method is exemplified by application to a right-circular conical cavity. [ABSTRACT FROM AUTHOR]