Re: Dual vs lens-focused crystal advantages?

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Re: Dual vs lens-focused crystal advantages?
Posted by: Gary Truemner , E-mail: loca2016@tor.hookup.net, on September 15, 1996 at 23:55:05:
In Reply to: Re: Dual vs lens-focused crystal advantages? posted by : Gerhard Splitt on September 09, 1996 at 16:30:49:
Thanks for the response.....
How does your response apply, in the case of immersion Ultrasonics? ...where focus, seems to be used instead of dual crystal design, in most applications...why?
: Klaus Matthies asked me to reply to this question as he feels not familiar with this
: subject.
: 1. I do not agree to the statement that lens-focused single crystal probes are more
: common for applications where near surface resolution is requested. To my
: experience, the near surface resolution of direct contact dual probes is much better
: than for direct contact single crystal probes. Even when the single crystal probe is
: focused there is still a zone of poor resolution after the transmission pulse or after
: the interface echo if a delay probe is used.
: 2. Of course, dual probes can be optimized by choosing the proper crystal material.
: For example, by using piezocomposite transducers the signal amplitude and
: resolution will be improved significantly. By taking different kinds of piezocomposite
: material for transmitter and receiver crystal you can match them to the electrical
: impedance of the transmitter and receiver electronics individually.
: 3. I see no reasons why not to use dual probes for critical tasks of near surface
: resolution.
: Gerhard Splitt
: : The original Dual crystal contact probes used for near surface resolution seem to have been superceded by lens-focused
: : single crystal probes.
: : Are there new crystal materials which would give Dual crystal probes an advantage over lens-focus probes? i.e. optimized
: : transmitter and receiver crystal material.
: : Other than assembly cost of Dual probes, are there clear reasons not to use Dual probes instead of lens-focus single crystal
: : probes?

Follow Ups:

Re: Dual vs lens-focused crystal advantages? Gerhard Splitt 12:22:25 9/18/96 (size: 4209) (2)

Re: Dual vs lens-focused crystal advantages? Gary Truemner 03:13:46 9/19/96 (size: 514) (1)

Re: Dual vs lens-focused crystal advantages? Gerhard Splitt 16:23:42 9/23/96 (size: 1415) (0)

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Comments:
: Thanks for the response..... : How does your response apply, in the case of immersion Ultrasonics? ...where focus, seems to be used instead of dual crystal design, in most applications...why? : : Klaus Matthies asked me to reply to this question as he feels not familiar with this : : subject. : : 1. I do not agree to the statement that lens-focused single crystal probes are more : : common for applications where near surface resolution is requested. To my : : experience, the near surface resolution of direct contact dual probes is much better : : than for direct contact single crystal probes. Even when the single crystal probe is : : focused there is still a zone of poor resolution after the transmission pulse or after : : the interface echo if a delay probe is used. : : 2. Of course, dual probes can be optimized by choosing the proper crystal material. : : For example, by using piezocomposite transducers the signal amplitude and : : resolution will be improved significantly. By taking different kinds of piezocomposite : : material for transmitter and receiver crystal you can match them to the electrical : : impedance of the transmitter and receiver electronics individually. : : 3. I see no reasons why not to use dual probes for critical tasks of near surface : : resolution. : : Gerhard Splitt : : : The original Dual crystal contact probes used for near surface resolution seem to have been superceded by lens-focused : : : single crystal probes. : : : Are there new crystal materials which would give Dual crystal probes an advantage over lens-focus probes? i.e. optimized : : : transmitter and receiver crystal material. : : : Other than assembly cost of Dual probes, are there clear reasons not to use Dual probes instead of lens-focus single crystal : : : probes?

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