Abstract
A number of gypsum specimens, prepared by deposition of plaster of Paris (CaSO4 0.5H2O) in water at 1:3 mass ratio, are studied in view of their suitability for use as diffuse reflectance standards in such field work as the remote-sensing from the aircraft.
Comparison of their spectral reflectances and goniophotometric characteristics with those of some samples of other materials revealed the following advantages of the gypsum; 1. high reflectance, 2. fairly flat spectrum, 3. nearly perfect diffuseness, 4. good reproducibility of characteristics and 5. easiness of access, preparation and handling.
In connection, gypsum mixed with a little amount of India ink is studied in the same manner and found to be useful and convenient as a gray reflectance standard.
