Calibration of the absolute spectral response of Raman spectrometers

A system for the calibration of the absolute spectral response of spectrometers is described using a standard reflector ‐ of the type used especially for colour measurements – as a secondary light source. In contrast to conventional light sources for calibrations, the radiance is approximately constant over the whole area of the source, and the angular characteristic is known for a large range of reflection angles φ. A special advantage is that the angular characteristic follows closely the Lambert‐cosine‐jaw in the region φ∼45°. The radiant flux can be calculated exactly for various experiemental conditions, especially for Raman spectroscopy.