Stretching fiber using piezo tranducers

Hi guys,
I have a collection of piezos I just bought for my lab, and I'd like to know if its possible to use them to induce strain on fiber which is mounted on it. An FBG fiber (theoretically) have 0.78 x 10[SUP]-6[/SUP] microstrain[SUP]-1[/SUP] response, so I'm not sure if a piezo transducer would be able to deliver enough strain if I'm driving it with only up to 5V.

The big question is: what's the best way to mount the fiber itself other than just gluing in on the piezo itsef?

Thanks guys.

Can you convert micro strain response into a metric distance equivalent?

You gave the max limit of the strain response of your fiber but not your desired window of operation. You won't get full deflection from 5 volts, and you don't say if this is for DC or AC strain production? I've never experimented with common piezo elements in a straight DC application but it should provide more deflection than when driven via AC.

As is commonly heard on the forum here, more information is required.

Hi Scead, thanks for the reply.
I'm going for DC, but I'm not sure if it deflects at a fixed position when subjected to the supply. What do you think?

As for the additional info needed, I really don't know where to begin, but let's just put it this way; After I mount the FBG on the piezo, whatever the mounting method would be (which I'd be open for suggestions, otherwise the most direct way is to glue both ends of the grating to the piezo, and apply voltage, and see it's spectral response via a Spectrometer.

The main issue is FBGs are not exactly as available as its electronic counterparts; therefore suggestions for a piezo-mounting method (with the piezos that I have) which produces the most deflection is very much needed. Do you also have an alternative on the piezo itself?

Thanks Scead.

I did a little research and I'm guessing this is for some kind of variable optical filter, or perhaps as a method to modulate an optical signal?

This is really a very complex and highly detailed concept to begin with which requires quiet a bit of understanding of the theory and way more math than I care to get into =)

I think piezo's could in theory work, but you have to work all the math out for the required displacement, and then you have to figure out how to mechanically construct it. The piezos you linked are common speaker type displacement is going to be incredibly small, they rely on resonance of their physical structure for efficiency, you got quiet a bit of math and some empiracle measurement to do.

This is on the mid to high end of college level graduate projects in optical engineering, way over my head!

Outside of piezo's what's wrong with a mechanical adjustment like a simple spring and adjustment screw? That could be automated with an encoder on a gear motor shaft.

I kind of get the rough idea what you're trying to do which is either modulate an optical signal, or create an adjustable spectral filter, but like I said, you're short on details and long on complex and involved ideas.

haha, yeah I knew that this thing is not hobbyist material. This is partly for my research on optical lasers, where my lab has all these fiber splicers and whatnot.

You're right; I'm trying to build an optical filter as part of a bigger optical circuit, but for now that's the concern-the filter itself. As for using motor, I'm just afraid that it might break the fiber. Also as you know, motors are battery suckers. I've built one:

View attachment 65714

That's a proper filter and it cost a bomb. I'm not using those anymore anyway, they're overkill with a 90nm range. I only need a 10nm range, which is achievable if you're using fiber.

Well I guess I'll just start with the original idea and see where it brings me.