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Technical Discussions
John Bower
John Bower
06:10 May-23-1997
Pitch-Catch in air

I am looking for equipment to do ultrasonic testing (pitch-catch) in air. I will be working over a range of 0 to 3 meters. I need millimeter resolution. Does anyone know of sources for pulsers, transmitters, receivers? I assume I need to work at 50 to 200 kHz or so, but I am having trouble finding speakers and microphones at these frequencies.



    
 
 
R.J. Freemantle
R.J. Freemantle
00:57 May-23-1997
Re: Pitch-Catch in air



    
 
 
Rolf Diederichs
Director, Editor, Publisher, Internet, PHP MySQL
NDT.net, Germany, Joined Nov 1998, 602

Rolf Diederichs

Director, Editor, Publisher, Internet, PHP MySQL
NDT.net,
Germany,
Joined Nov 1998
602
01:59 May-23-1997
Re: Pitch-Catch in air
: I am looking for equipment to do ultrasonic testing (pitch-catch) in air. I will be working over a range of 0 to 3 meters. I need millimeter resolution. Does anyone know of sources for pulsers, transmitters, receivers? I assume I need to work at 50 to 200 kHz or so, but I am having trouble finding speakers and microphones at these frequencies.

First I have some more questions.

Are you really want to do MATERIAL testing?

I don't think that it is possible to work up to 3 meters.
I hope that Jan O. Strycek QMI and panelist on this workshop will shear my doubt.
(Jan: what is the maximum distance?)

What material do you want to test?
You need millimeter resolution in the material?

Rolf Diederichs



    
 
 
Paul A. Meyer
R & D,
GE Inspection Technologies, USA, Joined Nov 1998, 47

Paul A. Meyer

R & D,
GE Inspection Technologies,
USA,
Joined Nov 1998
47
03:08 May-23-1997
Re: Pitch-Catch in air

: I am looking for equipment to do ultrasonic testing (pitch-catch) in air. I will be working over a range of 0 to 3 meters. I need millimeter resolution. Does anyone know of sources for pulsers, transmitters, receivers? I assume I need to work at 50 to 200 kHz or so, but I am having trouble finding speakers and microphones at these frequencies.

I assume you want to measure the distance between the transducer and a target. Ultrasonic Arrays, in Woodinville, Washington, USA, supplies systems with 0.1 mm resolution and a working range of several meters. I beleive there are several other companies supplying such systems. They are often used to do level measurement from above in tanks filled with fluid or powder. Polaroid, the camera company, will sell you an engineering development kit based on the distance ranging systen in there camera but it only has 25 mm resolution.
Paul Meyer (Krautkramer)



    
 
 
Linas Svilainis
R & D,
Kaunas University of Technology, Lithuania, Joined Nov 1998, 67

Linas Svilainis

R & D,
Kaunas University of Technology,
Lithuania,
Joined Nov 1998
67
06:29 May-23-1997
Re: Pitch-Catch in air
: I am looking for equipment to do ultrasonic testing
(pitch-catch) in air. I will be working over a range
of 0 to 3 meters. I need millimeter resolution.
Does anyone know of sources for pulsers, transmitters,
receivers? I assume I need to work at 50 to 200 kHz
or so, but I am having trouble finding speakers and
microphones at these frequencies.

Dear John,

We have an acoustic sonar for location in air
(http://vingis.ktu.lt/ultrasound/sonar.htm).
It depends what you need - milimeter resolution
or accuracy?
We also have system for small distance
measurement which was developed for CRT mask
positioning during manufacturing process.
It has 10um accuracy but it will not cover
more than 30mm.

Could be made as spin-off of Sonar...

Linas Svilainis


    
 
 
John Bower
John Bower
03:38 May-23-1997
Re: Pitch-Catch in air

: : I am looking for equipment to do ultrasonic testing (pitch-catch) in air. I will be working over a range of 0 to 3 meters. I need millimeter resolution.

: First I have some more questions.

: Are you really want to do MATERIAL testing?
: What material do you want to test?
: You need millimeter resolution in the material?

: Rolf Diederichs

First, I wish to thank Rolf for setting up this workshop, and all the others for responding.

No, I don't want to do material testing or air-coupled testing. I simply want to do echo location or position location in air. If I were looking for defects in steel, or trying to locate objects underwater, I would know of several sources of transducers and the associated electronics.

I am trying to do the same sort of thing with air as the material. The problem is to find transducers to couple sound to and from air at hundreds of kiloherz frequencies.

As a further complication, I want to do source location based on timing from multiple receivers. This means I want small transducers, to have very wide angle response. My present idea is to attach a source to the object I wish to locate, and I need to detect the signal at multiple locations to get millimeter accuracy in the source location. It is similar to Acoustic Emission source location. But the material is air.


    
 
 

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