enter image description here What is the rule-of-a-thumb ratio of lens' thickness to wavelength at which they can be designed using ray optics approximation? (The thickness is more relevant to gradient index lens, homogeneous lenses can be made arbitralily thin provided that you have a high enough refractive index material) Since lenses often have nontrivial shape, for simplicity sake let's consider a flat plate gradient index (otherwise it wouldn't be a lens) lens as shown on the picture. How many wavelengths thick at least should it be for the light to apparently take the path predicted by path integral?

  • $\begingroup$ Hi, welcome to Physics SE! Unfortunately, the question in its present state is off-topic here. We intend our questions to be potentially useful to a broader set of users than just the one asking, and prefer conceptual questions. Can you try making a question about some concepts that you'd need to solve this problem? Also mention any thoughts you currently have about the solution, and your assessment of their usefulness. $\endgroup$
    – user191954
    Jun 25, 2018 at 13:56
  • $\begingroup$ Am i supposed to edit this one or can i post a new question? $\endgroup$ Jun 25, 2018 at 14:01
  • $\begingroup$ I would recommend you improve this one, without deleting it. The SE algorithms usually don't like deleted posts. SE is pretty mysterious about how they filter posts and authors, but the standard advice is that if you delete posts with downvotes or flags, you move closer to being blocked from making posts. But don't worry, this is your first post, so they'll give you a decent bit of room to figure out how the site works :-) $\endgroup$
    – user191954
    Jun 25, 2018 at 14:05


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