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How to cancel a split image - is it actually possible?

  1. Jun 15, 2011 #1
    Hi all,

    A question: Is it possible to split a single image then use the two identical images to cancel each other resulting in a cancelled 'image'? If so, can anyone suggest a simple optical method that can be used to achieve this in real-time? Perhaps creating an anti-phase of the original image and combining them optically? Thanks.
    Last edited: Jun 15, 2011
  2. jcsd
  3. Jun 16, 2011 #2
    Can you clarify what you mean by image. Are you talking about a projected image onto a screen?

    You can "cancel" or destructively interfere with a grating. When polarized light reaches the grating an out of phase image is stimulated by the conductive bands in the grating causing the resulting combined amplitude of the light measured anywhere beyond the grating to be close to zero. Blackness.

    This is the technology behind 3D glasses, so that they can cancel the image in one eye.
  4. Jun 16, 2011 #3


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    For a projected image, a second image could be projected at the same screen to turn the combined image into some shade of grey or white.
  5. Jun 16, 2011 #4
    Actually it would be black. An out of phase image with equal magnitude and frequency would be no light at all. A grating at the lens would produce a very accurate out of phase image.
  6. Jun 17, 2011 #5
    For example, in a classic pin-hole camera, would it be possible to cancel the image of a person's face (the image projected at the back of the camera box) ? If so, any ideas how? Thanks.
  7. Jun 17, 2011 #6
    Okay. A test scenario would be the classic pin-hole camera where a face is the incoming image. I was wondering how one can get and project the out of phase version of the image to create the cancelled (zero image effect).
  8. Jun 17, 2011 #7


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    This would only be true if you were using vector addition of light waves. This is not possible without the sort of stability that's needed to make holograms.
    The proposal, as far as I can see, is to project an additional 'negative' image (in terms of intensity) so that the two images merge to produce uniform illumination at, as was said, half brightness.
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