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I have a question about a particular case of light diffraction. A laser light collides into a "hairline" mirror (I mean a straight line mirror that halves the wavelength dimension), see the image below. It's placed on a black wall that could absorb the whole light. For these reasons I suppose that the mirror reflects the light because it's a mirror, but the light interferes because the mirror is a barrier. Then I ask, what is the real phenomenon that occurs?

enter image description here

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Can you be more specific as the explanation is not proper ? – Nike Dec 1 '14 at 15:16
We suppose to have a very black wall that can absorb the 100% of the light and a tiny mirror with wavelength dimension and for this aim it can cause the diffraction. We point a laser toward the mirror. – denis Dec 1 '14 at 16:35
what is the result of this ideal experiment? – denis Dec 1 '14 at 16:36
I understand that the width of the mirror is half wavelength of the light. But that doesn't tell if one can obtain a fringe of minimum on the wall. The difference in pathlength to the wall is measured by following a plane of equal phase. One more thing: don't consider the laser source as point-like, i.e. for your problem I think that the laser beam may be approximated as a plane-wave. – Sofia Dec 1 '14 at 23:40

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