On-machine characterization of moving paper using a photo-emf laser ultrasonics method

Bruno F. Pouet; Emmanuel F. Lafond; Brian Pufahl; Gerald David Bacher; Pierre H. Brodeur; Marvin B. Klein

doi:10.1117/12.339961

4 February 1999 On-machine characterization of moving paper using a photo-emf laser ultrasonics method

Bruno F. Pouet, Emmanuel F. Lafond, Brian Pufahl, Gerald David Bacher, Pierre H. Brodeur, Marvin B. Klein

Proceedings Volume 3589, Process Control and Sensors for Manufacturing II; (1999) https://doi.org/10.1117/12.339961
Event: Nondestructive Evaluation Techniques for Aging Infrastructures and Manufacturing, 1999, Newport Beach, CA, United States

Abstract

Stiffness properties of paper materials can readily be characterized in the laboratory using conventional ultrasonic techniques. For on-line inspection on a paper machine, due to the high translation velocity and the somewhat fragile nature of the moving paper web, contact ultrasonic techniques using piezoelectric transducers are of limited use. To overcome this limitation, non-contact laser- based ultrasonic techniques can be used. Due to the rough surface of the paper, the reflected light is composed of many speckles. For efficient detection, the receiver must be able to process as many speckles as possible. Adaptive receivers using the photorefractive or photo-emf effects are characterized by a large etendue, and thus, are well suited for detection on paper and paperboard. Moreover, the translation velocity of the moving web implies that the detection system must adapt extremely quickly to the changing speckle pattern. In this work, a photo-emf receiver was used to detect Lamb waves excited using a pulsed Nd:YAG laser in moving paper. Experiments were performed using a variable-speed web simulator at speeds much higher than 1 m.s^-1. Results corresponding to various translation speeds are shown, demonstrating the feasibility of laser- based ultrasound for on-machine inspection of paper and paperboard during production.

Citation Download Citation

Bruno F. Pouet, Emmanuel F. Lafond, Brian Pufahl, Gerald David Bacher, Pierre H. Brodeur, and Marvin B. Klein "On-machine characterization of moving paper using a photo-emf laser ultrasonics method", Proc. SPIE 3589, Process Control and Sensors for Manufacturing II, (4 February 1999); https://doi.org/10.1117/12.339961

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