Re: Comparison of dry-coupled, air-coupled and EMAT transducers

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Re: Comparison of dry-coupled, air-coupled and EMAT transducers
Posted by: Yoseph Bar-Cohen , E-mail: Yoseph.Bar-Cohen@jpl.nasa.gov, on September 27, 1996 at 17:56:55:
In Reply to: Comparison of dry-coupled, air-coupled and EMAT transducers posted by : A. Anev on September 26, 1996 at 16:45:28:
It is possible to produce a dry-coupled transducer that is driven by
polymer piezoelectric materials (PPM). However, this application will
not be an effective use of these piezoelectric materials because of
the spectral range that is required. The useful range of dry-coupled
transducers is below 1MHz, on the other hand PPM transducers are
producing a reasonably high signals only at the MHz range. In
general, PPM are efficient receivers due to their low noise but they
are relatively weak transmitters.

Yosi

: What is the difference in the accuracy of dry-coupled, air coupled and EMAT transducers generally and regarding near surface and internal imperfections?
: Suppose all the transducers work at the accuracy at which they give the best results.
: Furthermore do you think polymer transducers can be used as dry-coupled ones?

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Comments:
: It is possible to produce a dry-coupled transducer that is driven by : polymer piezoelectric materials (PPM). However, this application will : not be an effective use of these piezoelectric materials because of : the spectral range that is required. The useful range of dry-coupled : transducers is below 1MHz, on the other hand PPM transducers are : producing a reasonably high signals only at the MHz range. In : general, PPM are efficient receivers due to their low noise but they : are relatively weak transmitters. : : Yosi : : : What is the difference in the accuracy of dry-coupled, air coupled and EMAT transducers generally and regarding near surface and internal imperfections? : : Suppose all the transducers work at the accuracy at which they give the best results. : : Furthermore do you think polymer transducers can be used as dry-coupled ones?

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