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beam width of focusing probe (Antonio Filippi)
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Materials Research Institute
Consulting to the NDT industry.

362 views
03:58 Nov-19-1999

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
172
beam width of focusing probe (Antonio Filippi)

reply by Udo Schlengermann
uschlengermann@krautkramer.de

The parameters you gave are valid for an unfocused flat probe.
Assuming a (1/4) inch probe of 10 MHz in water (6,35 mm dia)
this probe has its natural focus at 68 mm distance (nearfield length) and a beam width of 1,6 mm at a -6dB-threshold (measured with a point like reflector).

The 9 mm steel path is equivalent to 36 mm water path, so you have to use a water delay of 32 mm (68 mm -36 mm) to position the focus at the far surface of the steel plate.

This will not influence the beam width, if the beam is perpendicular to the plate.

Kind regards

Udo Schlengermann




 


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