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- Literature and internet only talk about the very basic case of an incident planar wave... can someone help me with an equally basic but perhaps more tricky case of a spherical wave and the dependence of the diffraction pattern with the distance from source to pinhole?

Case (a) is the textbook of a planar incident wavefront and below it in the figure is the known simple formula for the central spot and fringes, or minima and maxima, angular distribution with respect to the optical axis.

So, the question here is regarding case (b). The position (usually estimated angularly, Θ) of the central spot and consecutive fringes is always the same, depending only on pinhole diameter and wavelength, according to the eqn. sin(

And also, if there is a different output pattern, is it dependent on

Thank you very much in advance!

So, the question here is regarding case (b). The position (usually estimated angularly, Θ) of the central spot and consecutive fringes is always the same, depending only on pinhole diameter and wavelength, according to the eqn. sin(

*Θ*) = m**λ*/*d*?? Regardless of the shape of the incoming wavefront?And also, if there is a different output pattern, is it dependent on

*ΔZ*, the distance from the source (e.g. fiber tip) to pinhole? If you put them closer (smaller*ΔZ*) the throughput will definitely be higher, but are the central spot size and fringe positions going to change?Thank you very much in advance!

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