NDT.net November 2006, Vol. 11 No.11

Commercial application of laser ultrasonics for the paper industry
Georgia Tech - LBNL team wins one of the prestigious R&D100 awards
for novel Laser Ultrasonics Stiffness Sensor
The Laser Ultrasonic Sensor, developed by members of the Environmental Energy Technologies Division and colleagues at the Institute of Paper Science and Technology at the Georgia Institute of Technology — a sensor and control system to ensure optimum paper quality and efficient use of trees, chemicals, and energy by measuring stiffness and shear strength as paper speeds through the production web.

August 21, 2006 - Atlanta, GA -- A Georgia Institute of Technology – Lawrence Berkeley Lab team has won one of the one hundred 2006 R&D100 awards in a competition among inventions developed in 2005.

The R&D awards competition has been held since 1963 and Georgia Tech had previously won one of the R&D awards in 1976, 1991 and 2003. The complete list of the R&D100 awards will be published in the September 2006 issue of R&D Magazine: http://www.rdmag.com/awards.aspx

Over the years, the R&D 100 Awards have recognized winning products with such household names as Polacolor film (1963), the flashcube (1965), the automated teller machine (1973), the halogen lamp (1974), the fax machine (1975), the liquid crystal display (1980), the printer (1986), the Kodak Photo CD (1991), the Nicoderm antismoking patch (1992), Taxol anticancer drug (1993), lab on a chip (1996), and HDTV (1998).

The Laser Ultrasonics Stiffness Sensor was developed by a team of scientists and engineers comprised of Paul Ridgway, Emmanuel Lafond, Ted Jackson, Chuck Habeger and Rick Russo, from the Institute of Paper Science and Technology at the Georgia Institute of Technology (Georgia Tech, IPST dept.), and the Environmental Energy Technologies Division of Lawrence Berkeley National Laboratory (LBNL).

The laser ultrasonic sensor will greatly improvethe cost and efficiency of paper manufacturing. Currently paper is either over-engineered, with added costs of raw materials, chemicals, and energy, or each three-ton paper roll is manually tested after it has been made to ensure no risk of rejection by the customer on basis of too low a stiffness. The new sensor measures stiffness quality automatically on the fly at up to 30 meters per second without touching the paper.

The sensor measures the dispersion of the acoustic shock waves in the frequency domain that propagate from a laser-induced excitation point, a function depending upon the paper's flexural rigidity and out-of-plane shear rigidity. A detection beam is reflected from a rotating mirror in a circular pattern, briefly traveling with the paper as it courses along the production belt. When the beam is perpendicular to the paper, a laser fires a pulse a few nanoseconds in duration that causes a microscopic thermal expansion, too small to mar the paper or affect how it absorbs ink but strong enough to send ultrasonic shock waves through the sheet. The waves propagate until they are registered by the detection beam.

The stiffness information coming from the sensor allows efficient and real-time process control of the paper machine and savings of raw materials and energy. Once the technology is widely in place, savings could reach hundreds of millions of dollars annually.

Emmanuel Lafond (Principle Investigator, Georgia Tech) said: “At IPST the late Pierre Brodeur was the instigator towards getting this idea and this project supported by the Dept. of Energy. When I started on this project in 1997 as a Post-Doc, nobody in the laser ultrasonics arena thought that it was possible to make meaningful laser ultrasonics measurements at 25 and 30 m/s (90 and 108 km/h) given the scientific and engineering challenges. Yet, with much dedication, hard work, and relentless perseverance we were able to construct a sensor that did this and measured stiffness accurately, not only in the laboratory but also in the difficult production environment of paper mills.”

The Laser Ultrasonic Sensor tracks and measures shock waves from laser ablation without stopping the paper or touching it during manufacture. Paul Ridgway (Staff Research Associate, LBNL) said: “Nine years ago, I never would have believed we would develop this technology into a commercial product of genuine value to the paper industry. It has been a privilege and often a pleasure to work together with my talented and dedicated colleagues at IPST at Georgia Tech"

Gary A. Baum, (President of PaperFuture Technologies LLC and Former VP Research at IPST) added: “IPST has worked for many years developing on-line sensors that could measure paper’s mechanical properties. It is very gratifying, therefore, to see the success of the non-contact laser ultrasonic stiffness sensor. The research team from IPST at Georgia Tech and LBNL are to be commended for their persistence and dedication. Most important, this sensor will revolutionize process control during papermaking.”

Nine years in the making, the sensor was funded by the Department of Energy's Office of Industrial Technologies as part of a partnership to improve the energy efficiency of several industries. Under this program, the American Forest and Paper Association created Agenda 2020, which outlines ways in which the forest products industry can improve industry competitiveness and environmental performance by using the tools of technology. Papermaking is a highly energy intensive process and is an obvious candidate for energy conservation technologies

For more information contact:
Emmanuel Lafond
(404) 894-3707
Paul Ridgway
(510) 486-7363

Institute of Paper Science and Technology
at Georgia Institute of Technology
500 10th Street, NW
Atlanta, GA 30332-0620
(404) 894-5700

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