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Laser experiment.

  1. Apr 8, 2009 #1
    Hi all, ive just got hold of a used helium neon 1 mW laser (spectra physics model 155) and would like to some experiments at home, does anyone know any good examples Thx
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  3. Apr 8, 2009 #2


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    You could get a diffraction pattern of a small slit or wire ( human hair works). Experiment with double slits, and many more.
    You could try to burn something, but you need a good lens and exact alignment.

    Its usual operation wavelength is 632.8 nm. Red part of the spectrum. So no chemical reactions that i can think of will occur (except very photosensitive materials).

    With a crystal of potassium titanyl phosphate and complicated assembly you could double it's frequency ( 316.4 nm ).
  4. Apr 8, 2009 #3


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  5. Apr 8, 2009 #4
    thx lok i'll try these (1st two)

    hi ive looked at holography, would it be possible to replace the photographic paper with a digital camera??
  6. Apr 8, 2009 #5


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    Not as such - you have no way of reconstructing the wavefront (ie viewing the hologram)
    These guys have done something similair with a digital camera http://www.me.jhu.edu/lefd/shc/LPho...Laser Pointer and Consumer Digital Camera.pdf although strictly it's more speckle interferometry than a hologram
  7. Apr 8, 2009 #6


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    Look for http://en.wikipedia.org/wiki/Arago_spot" [Broken].
    Last edited by a moderator: May 4, 2017
  8. Apr 8, 2009 #7
    You can make a simple Michelson-Morley interferometer and play around with wave interference.
  9. Apr 9, 2009 #8


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    A couple of quickies:

    Use a CD as a diffraction grating. From the diffracted beam angles, determine the spacing of tracks on the CD.

    Use a pin to make a small circular hole in a sheet of paper. Look at the diffraction patern.
  10. Apr 10, 2009 #9
    All good suggestions above. One of my favorites was measuring the wavelength of the laser with a ruler... Really... Generally need a steel ruler with lines that are etched into it to form your "grating".

    Lay the ruler down flat and bring the beam in at an extremely shallow angle and based on the angles present and the space in between the diffraction orders you can calculate the wavelength pretty accurately. Here is a good link for the lab.

  11. Apr 10, 2009 #10
    It's been a long time since I did it in school but i do remember doing a holography lab that uses the white light of the room as the reference? beam to complete the hologram so it can be viewed at any time. If not you do need the laser to actually view the hologram as well if it is used for both the object and reference beams.

    I'll see if i still have that stuff laying around anywhere and upload it. Note that it also takes a very stable optics table, a power meter so you can calculate the exposure time a decent amount of mirrors/mounts and the ability to develop the holographic plates... but it sure is fun!
  12. Apr 10, 2009 #11
    Keep thinking of things:P

    If you're interested in polarization it's easy enough to try with a couple of old sunglasses. Try to determine what the polarization of the laser is. Can you get the beam to cancel with one polarizer or does it take two? If you can manage to get a quarter-wave plate what happens when you put it inbetween the two polarizers that do cancel the beam?

    Also how does the polarization of a beam chance with reflection... take some data points and plot it out vs output power... :) Very cool stuff. Yay for photons.
  13. Apr 10, 2009 #12


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    I want a multi line argon... :(
  14. Apr 10, 2009 #13


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    You can make white light viewable holograms - they just have a restricted viewing angle.
    If you don't have an optical table, mirrors on sticks in a sandbox work well, so does glueing everything to a paving slab and sitting it on a bike inner tube.

    You can o hologram with film if you clamp it to a flat plate but it's a bit hit and miss, any fraction of a wavelenght movement ruins it.
  15. Apr 11, 2009 #14
    wow thx for all your replies, the holography looks good especially when you read how it works......thats why i love physics...... brilliant and thx too Lambduh some good ideas there

  16. Apr 11, 2009 #15
    hi Integral ive looked for the arago spot but noluck yet, have you any ideas on size of circular object or distance to shadow/object/laser thx
    Last edited by a moderator: May 4, 2017
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