Evaluation of Absolute Reflectance for Standardization Purposes

Details and principles of a technique for reflectance standardization through determination of absolute reflectance are presented. The method involves the use of a demountable, split test sphere whose single port can be presented to the specimen aperture of a spectrophotometer. Measurement of the apparent reflectance of the sphere port permits determination of the spectral absolute reflectance of the test sphere lining; the split sphere is arranged so that the result can be translated to the determination of reflectance of reference and working standards.