Amateur FTIR

Is it possible to build your own FTIR?

I don't mean from scratch, I mean is it possible to build one out of 'parts'.

I ask because I just bought the electronics and beamsplitter/moving mirror assembly from a Nicolet Spectrometer. The moving mirror is a 'porch swing' type so I don't need air for an air bearing, the KBr beamsplitter looks in excellent shape. It would be neat to get this working in a stand-alone mode.

I still need an laser and detector (working on it), but the real question is can I operate the electronics independently?

It came out of a Nicolet 5PC spectrometer, does anyone have info on the electronics, wiring?

Reply to
Douglas Taylor
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Sure, why not? :)

You may be better off ignoring the electronics except maybe the detector front-end and doing your own unless documentation is available.

You mean a laser for the reference?

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Reply to
Sam Goldwasser

I have given this some thought.... The electronic functions that are needed are:

  1. Amp to drive the mirror motor - sort of a saw tooth drive signal (audio freq bandwidth) 2. Laser signal phase lock loop - if the mirror moves at a constant speed the laser interference signal will be a sine wave in the audio spectrum, I think you couple this to the mirror drive to keep the mirror speed constant. 3. A/D trigger signal - you use the laser reference zero crossings to trigger the A/D 4. Start & End of scan - you need to know where the mirror is, either at the start of the scan or end and either direct the mirror drive circuit to tell the mirror motor to go forward or backward. 5. Digital interface - connect the A/D to a computer, monitor other signals.

Sounds like a lot of basic electrical circuit stuff, nothing exotic. Maybe it is possible to build.

Yes, an ordinary HeNe laser is what is used. The beamsplitter I have has a small circular area in the middle which is where the laser reference beam is directed. I comes out the other side of the interferometer into a small detector.

Reply to
Douglas Taylor

So these together form a constant reference frequency drive.

Is that a high enough sampling rate? I guess if it's IR, then the fringe signal for the unknown spectrum will be a lower frequency but you still need to obey Mr. Nyquist.

So it sounds like you have an interesting project if you're in it for the challenge. Even if you don't do the full FTIR, you could build a nice accurate wavemeter with what you have.

--- sam | Sci.Electronics.Repair FAQ:

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Reply to
Sam Goldwasser

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