High-accuracy true normal-incidence absolute reflectometer

A true normal incidence absolute reflectometer has been constructed and tested. It is shown that, for this type of reflectometer, the characterization of systematic errors and the measurement method adopted allow accuracies of ±0.2% to be achieved over the 350–750-nm wavelength range. The use of collimated light and the inclusion of a novel high-efficiency integrating sphere contribute substantially to this accuracy.