NDT.net - September 1999, Vol. 4 No. 9

Dynamic Focusing of Phased Arrays for Nondestructive Testing: Characterization and Application

R/D Tech inc. (Québec)
François MAINGUY
R/D Tech inc. (Québec), École de Technologie Supérieure (Montréal)
Corresponding Author Contact:
Email: info@rd-tech.com, http://www.rd-tech.com



Introduction to the Technology

Theory of Operation


Parameter Probe A Probe B
Geometryof the array Linear Annular
Frequency 4 MHz 7.5 MHz
Number of elements 16 32
Total aperture 40 mm x 30 mm 55 mm diameter
Dimensions of each element 2.4 mm x 30 mm Fresnel Distribution
Full aperture near-field 270 mm in steel 880 mm in aluminium
Wedge description 40 mm thick, Plexiglas LW @ 2700 m/s 75 mm water path LW @ 1480 m/s
Prefocalization none none
Table 2 :Description of the probe A used to scan with DDF.

Parameter Block #1 Block #2
Type of reflectors Side-Drilled Holes (SDH) of 2 mm of diameter Flat-Bottom Holes (FBH), diameter of 1 mm
Depth of reflectors 3, 5, 10 to 100 mm, 10 mm step 50 to 250 mm, 5 mm step
Material Carbon steel Aluminium
Surface quality Good Good
Velocity (LW) 5780 mm/s 6393 mm/s
Table 3 : Description of the blocks used to characterize the beam produced with DDF.

Parameter Probe A with Block #1 Probe B with Block #2
Acquisition system Tomoscan 68040 V3.58 micro-Tomoscan
Phased-array unit Focus 16/64 Focus 64/256
Scanner Rover Water tank
Scanner driver MDU-04 MCDU-02
Table 4 : Description of the R/D Tech systems used.




  1. "Optimizing the Radiation Pattern of Sparse Periodic Linear Arrays", Lockwood, Li, O'Donnell, Foster, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 43, n°1, January 1996
  2. "Ultrasound Synthetic Aperture Imaging : Monostatic Approach", Ylitalo, Ermert, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 41, n°3, May 1994
  3. "Review of practical applications of Ultrasonic phased-array in NDT", Lamarre A., Mainguy F., Q-NDE Conference, Snowbird, Utah, July 1998
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