Connect with us

Amateur FTIR

Discussion in 'Electronic Repair' started by Douglas Taylor, Nov 10, 2005.

  1. 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?
     
  2. 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?

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name is included in the subject line. Or, you can
    contact me via the Feedback Form in the FAQs.
     
  3. 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.
     
  4. 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: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name is included in the subject line. Or, you can
    contact me via the Feedback Form in the FAQs.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-