Laser-ultrasound detection systems: a comparative study with Rayleigh waves

Using laser-generated Rayleigh waves in the thermoelastic regime as an ultrasonic source, a range of ultrasonic detector systems have been evaluated experimentally for their sensitivity. Systems examined were those based on electromagnetic acoustic transducers (EMATs), a non-steady state photo-emf detector, a confocal Fabry-Perot interferometer (CFPI) and a differential optical beam deflection (OBD) detector. These detector systems had their own range of frequency responses within the range of approximately 100 kHz to 140 MHz. However, experimental conditions in this study limited the upper frequency range to 22 MHz. For comparison, signal-to-noise ratios were normalized with respect to both the experimental bandwidth, and, in the case of laser detection, the incident laser intensity. Results showed that for remote monitoring at a distance greater than 0.2 m, optical systems based on the photo-emf detector and the CFPI offered similar performances from a machine-finished aluminium surface. OBD measurements are not possible on such a surface. However, for typical stand-off distances of 0.25 mm or less, cost-effective EMATS provided an alternative form of detector.

[1]  Ernst Meyer,et al.  Multifunctional probe microscope for facile operation in ultrahigh vacuum , 1993 .

[2]  A. J. Rogovsky,et al.  Development and application of ultrasonic dry-contact and air-contact C-scan systems for nondestructive evaluation of aerospace composites , 1991 .

[3]  Nonsteady-state photo-EMF in thin photoconductive layers , 1994 .

[4]  Zhang Yinping,et al.  A simple method, the -history method, of determining the heat of fusion, specific heat and thermal conductivity of phase-change materials , 1999 .

[5]  J. Monchalin,et al.  Laser ultrasonic generation and optical detection with a confocal Fabry-Pérot interferometer , 1986 .

[6]  Jean-Pierre Monchalin,et al.  Broadband optical detection of ultrasound by optical sideband stripping with a confocal Fabry–Perot , 1989 .

[7]  R. Dewhurst,et al.  Fibre optic system for the monitoring of asymmetric Lamb wave modulation in thin films , 1997 .

[8]  S. Stepanov,et al.  Non‐steady‐state photoelectromotive force in semiconductor crystals with high light absorption , 1993 .

[9]  H. Ogi,et al.  Line-focusing electromagnetic acoustic transducers for the detection of slit defects , 1999, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  R. J. Dewhurst.  OPTICAL SENSING OF ULTRASOUND , 1990 .

[11]  Richard J. Dewhurst,et al.  Noncontact detection of surface‐breaking cracks using a laser acoustic source and an electromagnetic acoustic receiver , 1986 .

[12]  R. Dewhurst,et al.  Optical remote measurement of ultrasound , 1999 .

[13]  M. Fink,et al.  Optical generation and detection of elastic waves in solids , 1994 .

[14]  R. Dewhurst,et al.  New field formulas for the Fabry - Pérot interferometer and their application to ultrasound detection , 1998 .

[15]  Marvin B. Klein,et al.  Design and engineering of photorefractive materials for use in adaptive laser ultrasonic receivers , 1998, Photonics West.

[16]  D. Hutchins,et al.  Air-coupled piezoelectric detection of laser-generated ultrasound , 1994 .

[17]  H. Ogi,et al.  An SH-wave EMAT technique for gas pipeline inspection , 1999 .

[18]  Richard J. Dewhurst,et al.  A LASER-BEAM DEFLECTION TECHNIQUE FOR THE QUANTITATIVE DETECTION OF ULTRASONIC LAMB WAVES , 1993 .

[19]  Gilmore J. Dunning,et al.  Materials inspection and process control using compensated laser ultrasound evaluation (CLUE): demonstration of a low-cost laser ultrasonic sensor , 1996, Photonics West.

[20]  David A. Hutchins,et al.  Laser generation as a standard acoustic source in metals , 1981 .

[21]  Richard J. Dewhurst.  Optical ultrasonic sensors for monitoring from industrial surfaces , 1994, Other Conferences.

[22]  R. Dewhurst,et al.  A FIBRE-OPTIC DETECTION SYSTEM FOR LASER-ULTRASOUND LAMB-WAVE EXAMINATION OF DEFECTS IN THIN MATERIALS , 1996 .

[23]  Richard J. Dewhurst,et al.  Modelling of confocal Fabry-Pérot interferometers for the measurement of ultrasound , 1994 .

[24]  Marvin B. Klein,et al.  Robust laser-based detection of Lamb waves using photo-EMF sensors , 1998, Smart Structures.

[25]  M. Clark,et al.  Application of laser ultrasound for surface acoustic wave microscopy , 1998 .

[26]  Andrew C. Tam,et al.  Optical monitoring of photoacoustic pulse propagation in silicon wafers , 1985 .

[27]  R. Dewhurst,et al.  A Study of Lamb Wave Interaction with Defects in Sheet Materials Using a Differential Fibre-Optic Beam Deflection Technique , 1996 .

[28]  S. Stepanov,et al.  Detection of optical signals with high-amplitude phase modulation by adaptive photodetectors. , 1993, Applied optics.

[29]  S. Stepanov,et al.  Sensitivity of non-steady-state photoelectromotive force-based adaptive photodetectors and characterization techniques. , 1994, Applied optics.

[30]  S. Stepanov,et al.  Non-steady-state photoelectromotive force in crystals with long photocarrier lifetimes , 1993 .

[31]  James B. Spicer,et al.  Quantitative theory for laser ultrasonic waves in a thin plate , 1990 .

[32]  S. M. Jawad,et al.  AN AUTOMATIC STABILIZATION SYSTEM FOR A CONFOCAL FABRY-PEROT-INTERFEROMETER USED IN THE DETECTION OF LASER-GENERATED ULTRASOUND , 1993 .

[33]  Hideki Kawakatsu,et al.  Simultaneous optical detection techniques, interferometry, and optical beam deflection for dynamic mode control of scanning force microscopy , 1997 .

[34]  J. Monchalin.  Optical Detection of Ultrasound , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[35]  Richard J. Dewhurst,et al.  Estimation of the thickness of thin metal sheet using laser generated ultrasound , 1987 .

[36]  S. Stepanov,et al.  Applications of photorefractive crystals , 1994 .

[37]  Jean F. Bussière,et al.  Laser-ultrasonic monitoring of phase transformations in steels , 1998 .

[38]  A. Overhauser,et al.  Electromagnetic generation of ultrasound in metals , 1977 .

[39]  J. Monchalin.  Optical detection of ultrasound at a distance using a confocal Fabry–Perot interferometer , 1985 .

[40]  M. J. Cunningham,et al.  Measurement of the modal shapes of inhomogeneous cantilevers using optical beam deflection , 1995 .

[41]  R. Dewhurst,et al.  A differential fibre- optic sensor for the monitoring of ultrasound , 1998 .

[42]  David A. Hutchins,et al.  Studies of laser‐generated ultrasound using a micromachined silicon electrostatic transducer in air , 1994 .

[43]  Laser Induced Sheet Waves for Investigating Anisotropy in Polymer Film , 1990 .

[44]  Christopher Edwards,et al.  A laser–EMAT system for ultrasonic weld inspection , 1999 .