Apparatus (10) and methods for measuring dark and bright reflectances of translucent sheet material (2) are disclosed. The apparatus (10) comprises first optical means for illuminating one side of the sheet material (2) with a source of electromagnetic radiation. A portion of the radiation is transmitted...http://www.google.com/patents/US4944594?utm_source=gb-gplus-sharePatent US4944594 - Apparatus and method for measuring dark and bright reflectances of sheet material
