Window screen focuses bricks beyond?

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Can a uniform diffraction grating (a window screen) alone focus objects (bricks on a building beyond) so that a nearsighted observer (I) can better image them?
 
Can a uniform diffraction grating (a window screen) alone focus objects (bricks on a building beyond) so that a nearsighted observer (I) can better image them?
Diffraction gratings don't focus things to my knowladge. However, what you may be expieriencing might have something to do with Morie Patterns.
 
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I say this without having read the link (sorry im lazy its late :P) but i think he means that you could change the path of the light rays with defraction and effectively use it as a lens.
 

Curious3141

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Can a uniform diffraction grating (a window screen) alone focus objects (bricks on a building beyond) so that a nearsighted observer (I) can better image them?
If you mean that things seem to be in better focus when you stand right up close to a fine mesh and peer through it at distant objects, then it is likely the pinhole effect is negating your refractive error.

Read this for a very simple explanation : http://www.myopia.org/pinholes.htm
 
Last edited by a moderator:
3,073
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Thanks, folks. It had me fooled! Indeed it must be a Moire pattern rather than a pinhole effect, since there were many apertures contributing to the interference, without substantial loss of light. I guess approximate coherence is cancelled out with many "pinholes." Two great suggestions that I initially overlooked.
 

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