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Overlapping lazers

  1. Feb 8, 2010 #1
    Is it possible two have two beams of light crossing to give the illusion of a small point of light in the air?
  2. jcsd
  3. Feb 8, 2010 #2


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    No, you can't "see" a laser beam from the side unless the light is being scattered from something (e.g. dust). Using two lasers won't make a difference.
  4. Feb 8, 2010 #3
    Just like what happens when two searchlight beams cross. Something in the air(dust, water particles, etc...) must of course be present.
    In any event, at the point of beam intersection, there are more photons available for scattering than from one beam alone.
  5. Feb 8, 2010 #4
    Two lasers intersecting in empty space won't have any effect on each other. Two lasers intersecting in a medium that has certain illumination-dependent properties is a bit more useful.

    Something similar is done in at least two different types of 3D displays. One uses two infrared lasers scanning a glass cube doped with a material that fluoresces visibly when illuminated by both simultaneously. Color can be achieved using different lasers to light up different fluorescent dopants. A block of glass big enough to be a useful display would be both massive and extremely expensive, though.

    Another works in air, and instead of using multiple lasers intersecting at a point, uses a single wide beam focused to a point to ionize the air to the point that it glows. This works in open air, but requires dangerously powerful lasers, and doesn't do color. Something similar is used to "etch" 3D shapes inside a block of glass:
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