US 7,321,425 B2
Sensor and methods for measuring select components in sheetmaking systems
Frank M. Haran, North Vancouver (Canada)
Assigned to Honeywell International Inc., Morristown, N.J. (US)
Filed on Dec. 20, 2004, as Appl. No. 11/18,167.
Prior Publication US 2006/0132796 A1, Jun. 22, 2006
Int. Cl. G01J 3/28 (2006.01); G01J 3/06 (2006.01); G01J 5/02 (2006.01)
U.S. Cl. 356—326  [356/308; 250/339.01] 35 Claims
OG exemplary drawing
 
1. A sensor, for measuring at least one component in a composition, that comprises:
a broadband light source that generates light;
an acousto-optic tunable filter (AOTF);
optics that direct a beam of light at the AOTF, wherein the AOTF is tuned to pass detection light having a desired wavelength range to detect a concentration of the at least one component in the composition;
a screen that directs the detection light of known wavelength to the composition;
a detector that receives light that emerges from the composition; and
a control signal generator that provides the AOTF with at least one desired wavelength range that is characteristic of the least one component in the composition;
wherein the composition comprises paper, and wherein the sensor detects at least one of: a level of cellulose in the paper, a level of calcium carbonate in the paper or paper coating, a level of clay in the paper or paper coating, and a level of latex in the paper or paper coating.