Paper machine optical monitoring device and method

Abstract From the Canadian patent

In an illustrated embodiment brightness, color, opacity and, fluorescent contribution to brightness are measured by an on-line sensing head providing for simultaneous measurement of transmitted and reflected light, The instrument is designed so as to be capable of transverse scanning of a moving paper web on the paper machine. An optical window member serves as a backing for the web for reflectance measurements and is in series with the web with respect to transmittance measurements. The optical window itself is selected as to its reflectance and transmittance so as to provide for periodic standardization of the instrument in an off-sheet position.