Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Quarter wave plate

  1. Sep 27, 2005 #1

    hen

    User Avatar

    Hello everybody,
    I would like to put a quarter wave plate in my microscope (between two
    crossed polarizers).

    In every book i saw so far, the plate was just before the upper
    polarizer, and after the specimen.

    my question is - can i put the plate before the specimen?
    so the path will be : light source, polarizer, plate, specimen,
    polarizer.
    note: my specimen is birefringence object.
    the way i see it, phase differences are added together, so is there a
    problem?

    Thanks!
    Hanan.
     
  2. jcsd
  3. Sep 27, 2005 #2

    Claude Bile

    User Avatar
    Science Advisor

    My initial impression is no, it shouldn't matter.

    Claude.
     
  4. Sep 28, 2005 #3
    Have you ever used a LASER to replace your light source, I did this years back when I had my old microscope, Images seem to be enhanced, but you have to make sure the LASER beam is set to an adjusted angle so the beam doesn't fully enter the lens array.

    You have to be very careful or it can cause eye problems, I use to use the projector lens so I didn't have to look directly in the eye piece.

    LASER light gives a much better luminous image.

    it was a pocket LASER from a gift machine, had about a 1000ft range. cost me 50 cents to win.

    never look directly at LASER light for fear of going blind. :smile:
     
    Last edited: Sep 28, 2005
  5. Apr 9, 2008 #4
    I have a need for 2 things. One, I am told, does not exist: a broadband, zero-order, quaterwave plate (200 to 850nm) and the other is money to buy them.
    If I can't buy it, I'd like to make it. Can anyone tell me whether I can make a quarterwave plate and if I can, is there a broadband version out there?
    My goal is to allow a human eye to see circularly polarized light (without the aide of a camera).
     
  6. Apr 10, 2008 #5

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    A reasonably good retarder can be made with layers of cellophane tape becasue the tape is birefringent. Calibrate the tape by placing it between crossed polarizers.

    A broadband zero-order quarterwave device exists- a Fresnel rhomb.

    http://www.klccgo.com/

    I can't help you with the money part.
     
  7. Apr 10, 2008 #6

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    What are you trying to do? Putting the quarter wave plate prior to the speciment will simply illuminate the sample with (for example) circularly polarized light, depending on the orientation of the plate. Putting it after the specimen would be more interesting, I would expect.

    DIC microscopy uses a pair of prisms rather than retarders, becasue it uses interference to increase the contrast.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?