Patent ID: 7081594

Claim:
A detection device for differentiating between a paper product containing less than a selected amount of lignin and a paper product containing more than the selected amount of lignin, the paper products being of the same color or of a different color, comprising a light source comprising an ultraviolet component positioned to emit light to strike the paper product, a detector for detecting ultraviolet light and generating an electrical signal proportional to an intensity of detected ultraviolet light, the detector being positioned to detect ultraviolet light diffusely reflected off of the paper product, an optical filter disposed between the paper product and the detector to eliminate components of diffusely reflected light outside of the ultraviolet range, and an instrument comprising a computer programmed to compare the level of the electrical signal to a predetermined reference level and to output a logic high signal or a logic low signal to indicate that the paper product contains more or less than the selected amount of lignin, for measuring a level of the electrical signal, wherein the level of the electrical is compared to a reference level to determine whether the paper product contains less than or more than the selected amount of lignin.