Simultaneous measurement of moisture content and basis weight of paper sheet with a submillimeter laser

US4755678A · kind A · utility

Assignee

• The Board of Trustees of The University of Alabama · US

Inventors

• Jerald R. Izatt · Northport, US
• Russell Boulay · Magnolia Trace, CA
• Richard Gagnon · San Clemente, US
• Bernard Drouin · Magnolia Trace, CA

Key dates

• Filing date: Jul 28, 1987
• Grant date: Jul 5, 1988
• Expiry date: Jul 28, 2007

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2021/8663
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A system for detecting simultaneously the moisture content and basis weight of paper is disclosed utilizing a submillimeter laser source of radiation of two different wavelengths which is subsequently scanned across the face of the paper. A plurality of detectors placed on the side of the paper opposite the laser supplies the transmittance information for each of the wavelengths to a microcomputer which in turn calculates the moisture content and the basis weight of the material. The two different wavelengths of submillimeter radiation are produced by either a pair of submillimeter lasers pumped by a continuous wave CO.sub.2 laser or by a single submillimeter laser pumped by a waveguide type continuous wave CO.sub.2 laser whose output is controlled by a piezoelectric crystal tuned resonator in order to provide the required two separate wavelengths alternating in time which are output in the single beam of the submillimeter laser.