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Thread: Can it be done?

  1. #1
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    Default Can it be done?

    My research mentor and I thought it would be neat to make a hologram which captured the image of a laser pointer- including the beam being emitted.

    Given we are using a 4mw 635 as the reference/object beam, and that the film was made for 633nm, I asserted that we must use one of those 300mw Mitsubishi diodes to have a bright enough beam to be captured.

    Now, since we're both new to holograms, I was wondering if the beam would even create an image on the film at all, since its exposure to the film is not referenced to the same reference beam (the 4mw thorlabs unit).

    At best, I would like to think that we could make an ordinary hologram of the laser's shape, and then after exposure, blow a continuous stream of smoke through the laser's beam when turned on. I'm thinking that the scattering of the light off the smoke should land some photons on the film for the beam capture, but I do not know if there will actually be an image-bearing interference pattern made by the beam scatter.

    Any ideas? Is it worth a shot?


  2. #2
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    So you're betting you can get light to reflect off of light?

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    I wonder if you could use compositing as a way to get around this.

    Can you copy a hologram from a hologram?

    If so maybe you could record an image of the laser beam from the pointer to ordinary film in low light so only the beam is visible from the same position that holographic film will be placed.

    Then record the hologram from exactly the same position.

    Then composite the two images together in a final recording.

    However, something is telling me though that its unlikely you can copy a hologram from a hologram.

  4. #4
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    Quote Originally Posted by laserist View Post
    So you're betting you can get light to reflect off of light?
    No. The would have to be scattering via smoke continuously blown across the beam. So while the reference beams scatters back to the film, could the scattering of the laserpointer's beam interfere to create an image?

    Or perhaps to capture the beam on film, I would have to project my reference onto the film as would normally be done, and then simply expose the film to the scattering of the laser beam..

    Quote Originally Posted by White-Light View Post
    I wonder if you could use compositing as a way to get around this.

    Can you copy a hologram from a hologram?

    If so maybe you could record an image of the laser beam from the pointer to ordinary film in low light so only the beam is visible from the same position that holographic film will be placed.

    Then record the hologram from exactly the same position.

    Then composite the two images together in a final recording.

    However, something is telling me though that its unlikely you can copy a hologram from a hologram.
    That's also what I was thinking about. Making one image at a time, and then superimposing them together to get the entire effect.

    Is there any way to do this?

    Meh...


  5. #5
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    The only way to do it is to use a pulsed laser to make the hologram. Send one of the object beams up through the hollowed out laser pointer and through the right amount of smoke to scatter it toward the recording plate. Use other object beams to illuminate the outside of the pointer body and whatever other scene there is, but that front light can't be scattered by the smoke (it will anyway, hence "the right amount of smoke"). This would be a great project for Ed Wesly in Chicago, who has an operational pulsed ruby laser in a holographic studio.

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    Meatball, with regards to multiple lasers, unless the coherent sources are "locked" to each other there is no interference. You could even overlap two different beams from two HENE tubes and see no mutual interference.*

    So the pointer beam has to come from the laser that is imaging the film.

    The scatter from the smoke will have to be very bright. Pulsed Ruby excels at this.

    *With some work, even a tiny amount of reflection, could lock the two tubes.

    Steve

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    Yes, I was going to chime in that the only real way to do this would be to use a pulsed laser, as the objects would be the smoke floating in air to show where the beam is. Plus the "beam" that appears to come out of the pointer would have to be derived from the laser that is doing the holographic recording.

    And yes, one can make a hologram of a hologram, it is done all the time in getting an image to straddle the film plane.
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