Wondering about the initial signal from ultrasonic transducer

[Tah]

Hi,

I have two ultrasonic transducers and a pulser-receiver(5072PR).

One is the contact transducer, A120S (6MHz), from Olympus and the other is also contact mode transducer, but it is a customized ring-type transducer (2.X MHz) (like doughnut).

I have two questions.

First, when I turn on the pulser-receiver, the initial line signal occurs from ultrasonic transducer.
I was wondring what is this signal.

Second, the two different transducers have different signal shape as shown below.
The signal from the customized transducer look so shoddy and dirty.
Why is that? and how to improve this kind of noisy signal?Please let me know. I'm so curious about all of that.

http://postfiles16.naver.net/20130416_207/jameskimes_1366102149606wPCbI_JPEG/x.png?type=w2

 

[enc08]

The signal you first see might just be an artefact of the circuit powering up. More details?

Can't see the picture you posted. In what way is the transducer customised?

 

[Bobbywhy]

Hi,

I have two ultrasonic transducers and a pulser-receiver(5072PR).

One is the contact transducer, A120S (6MHz), from Olympus and the other is also contact mode transducer, but it is a customized ring-type transducer (2.X MHz) (like doughnut).

I have two questions.

First, when I turn on the pulser-receiver, the initial line signal occurs from ultrasonic transducer.
I was wondring what is this signal.

Second, the two different transducers have different signal shape as shown below.
The signal from the customized transducer look so shoddy and dirty.
Why is that? and how to improve this kind of noisy signal?


Please let me know. I'm so curious about all of that.

http://postfiles16.naver.net/20130416_207/jameskimes_1366102149606wPCbI_JPEG/x.png?type=w2

1. According to the Olympus Transducer website, contact transducer part number A120S-RM operates at 7.5 MHz, and not at 6 MHz. Can you explain this discrepancy?

2. Olympus provides typical "records of the waveform and spectrum of each transducer is maintained and can be accessed for comparative or statistical studies of transducer characteristics." Have you compared these signal shapes to your measurements?

3. The driving waveforms applied to transducers may look "shoddy and dirty" to you, but what matters is the system performance. Are you receiving echoes that contain the desired signal quality?

Bobbywhy

 

[Tah]

1. According to the Olympus Transducer website, contact transducer part number A120S-RM operates at 7.5 MHz, and not at 6 MHz. Can you explain this discrepancy?

2. Olympus provides typical "records of the waveform and spectrum of each transducer is maintained and can be accessed for comparative or statistical studies of transducer characteristics." Have you compared these signal shapes to your measurements?

3. The driving waveforms applied to transducers may look "shoddy and dirty" to you, but what matters is the system performance. Are you receiving echoes that contain the desired signal quality?

Bobbywhy

1.
Yes, you're right.
7.5MHz is correct for A120S, not 6Mhz.

2. Olympus provides typical "records of the waveform and spectrum of each transducer is maintained and can be accessed for comparative or statistical studies of transducer characteristics." Have you compared these signal shapes to your measurements?

I've already done lots of experiments with those two transducers to measure the thickness of an object and distinguish two or three-layered materials which have different material density in each layer.
The signal from A120S was so clear to see the results but the customized ring-type transducer was so poor from sensitiviy and lots of noise.

3. The driving waveforms applied to transducers may look "shoddy and dirty" to you, but what matters is the system performance. Are you receiving echoes that contain the desired signal quality?

I was of course receiving echoes. And as you can see the image, the A120S showed clean signal and good performance, however the signal from the customized transducer showed poor signal. It significantly overlaps the time region (x-axis in the oscilloscope) that is important for measuring the thickness of thin materials.
I'm curious that is this due to the geometry of ring-shaped transducer(single element) or lower central freuqnecy(2.X MHz)?

 

[Bobbywhy]

As for your first question: "First, when I turn on the pulser-receiver, the initial line signal occurs from ultrasonic transducer. I was wondring what is this signal."

Will you please be more explicit?:
1. What is an "initial line signal?
2. Which transducer is connected to the pulser-receiver?
3. Exactly where is your O'scope probe connected?
4. Are you describing the "transmitting" waveform, or the "received" echo waveform?

As for your “ring-type” customized transducer:
1. What is the manufacturer and part number?
2. Are you using the same pulser-receiver for both different transducers? If the ring-shaped transducer is resonant at 2.X MHz can you expect to drive it with a pulser for a 7.5 MHz transducer?
3. What is the sound field of this “doughnut-shaped” transducer? Specifically, where are the near-field and far-field compared to your “distance of interest”?
4. Do you know the beam width and focal zone?
5. These, plus a few other characteristics of the torriodal transducer’s sound field may explain why you see that waveform. Furthermore, it’s possible that the pulser is not compatible with that customized transducer, resulting in the observed waveform. Is the piezo-electric material the same as your A120S? Beam patterns from the simple A120S and the torriodal will be significantly different, resulting in the long-time decaying echo signal.

By the way, here is the Olympic technical manual:
http://www.olympus-ims.com/data/File/panametrics/panametrics-UT.en.pdf

Bobbywhy

 

[NascentOxygen]

Second, the two different transducers have different signal shape as shown below.
The signal from the customized transducer look so shoddy and dirty.
Why is that? and how to improve this kind of noisy signal?

Your photos initially didn't reveal themselves. So I extracted the URL and viewed them independently. When I came back to see whether I could post so they did show, I found them displayed properly.

Not sure whether to attribute that oddity to PF or naver.net

http://postfiles16.naver.net/20130416_207/jameskimes_1366102149606wPCbI_JPEG/x.png?type=w2