No interference pattern in double slit when there is a lens?

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Why does the interference pattern of the photon go away when one places a convex lens far away from the two slit to only show a particle build up of the two slits?

This is the experimental set up, the lens is in place far after the photons pass through the two slit and hit the back wall in a particle distribution of the two slit, not a wave. Why does this happen?

 

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This is the experimental set up, the lens is in place far after the photons pass through the two slit and hit the back wall in a particle distribution of the two slit, not a wave.

Tthe idea of wave-particle duality just leads to more confusion than clarity here.

Check the phase differences for each point on the screen, and you see why the interference (and even single-slit patterns) disappears.