Why Does a Convex Lens Create a Flower-Like Light Pattern?

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Discussion Overview

The discussion revolves around the phenomenon observed when light passes through a convex lens and a small aperture, resulting in a flower-like light pattern on a surface. Participants explore the underlying reasons for this pattern, considering aspects of optics and light behavior.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes a setup involving a convex lens and a small hole, noting the resulting flower-like pattern and asking for explanations.
  • Another participant suggests that the pattern may be a type of lens flare, requesting visual evidence to support this claim.
  • A later reply proposes that the phenomenon could be related to the way cameras and human eyes capture light, suggesting similarities in how lens flare occurs in both systems.
  • Another participant hypothesizes that light scattering from irregularities around the hole may contribute to the observed pattern, recommending an experiment to smooth the hole's edges.
  • One participant mentions diffraction effects as a potential cause for the flower-like shapes seen in the light pattern.

Areas of Agreement / Disagreement

Participants express differing views on the cause of the flower-like pattern, with no consensus reached. Some suggest lens flare, while others propose scattering and diffraction as explanations.

Contextual Notes

Participants note the importance of the hole's smoothness and the role of diffraction, but the discussion does not resolve the underlying assumptions or definitions related to these optical phenomena.

Who May Find This Useful

This discussion may be of interest to individuals exploring optics, light behavior, and the effects of lenses in both practical and theoretical contexts.

swaroop
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I have a long tube (aout 30 cm) with a convex lens of diameter 7.5 cm on the one end and a small hole of diameter 2 cm on the other. When i shine a light through the hole and let it pass through the lens, i get a flowery pattern on the wall, looked very strange to me. There is a maxima in the center as expected, then dark for a little further and then patches of light all around the center that resemble petals.

Why is this pattern formed?
Note: This pattern does not appear to form without an apperture smaller than the lens, like a hole.
 
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Seems like some kind of lens flare. Hard to tell. Can you post a picture?
 
Thanks for replying. Here's the pic:
jqhshx.jpg
 
After seeing the picture I still think it is some kind of lens flare.
 
Thanks, I thought this kind of thing only happened in cameras..
 
I'm new to these forums, and so far I find them very intriguing. Anyways, the following is to the best of my knowledge, feel free to correct me where I'm wrong. Cameras work just the same as our eyes do. They capture light at a certain moment to generate an image. Though, cameras have something our eyes don't-- Glass lenses as opposed to our organic lenses. This scenario presents a glass lens similar to that of a camera's external lens, with spacing, as in most professional cameras. Is it so crazy to think, then, that we can reproduce lens flare not with a camera, but with our eyes themselves? I think not, given proper conditions, as provided above.
 
I'd guess it's simply light scattering from small irregularities around the hole. An experiment you can do is to try to make the hole as smooth as possible and see what the pattern is.
 
light passing through a small hole to an big aperture, it gets scattered, a diffraction effect also takes place, by which you cam see the flowery shapes.
 

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