What is the explanation for this diffraction pattern?

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Discussion Overview

The discussion revolves around the observation and explanation of an asymmetrical diffraction pattern produced using a green LED laser and a specific slit setup. Participants explore the nature of the diffraction pattern, its characteristics, and the factors influencing its formation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes producing an asymmetrical diffraction pattern and questions whether this phenomenon is novel or previously explored by others.
  • Another participant asserts that diffraction patterns can arise from a single edge and that fringe spacing is influenced by the wavelength and distance to the screen, which varies in the described setup.
  • A participant expresses confusion about the progressive nature of the pattern, suggesting it may be a result of interference from both edges of the slit.
  • Further clarification is sought regarding the specific shape and dimensions of the slit, emphasizing that the depth and width of the slot are significant in determining the diffraction pattern.
  • Details about the experimental setup are provided, including the wavelength of the laser, distance to the target, and the configuration of the aluminum panels used as the slit.

Areas of Agreement / Disagreement

Participants have differing views on the novelty of the observed diffraction pattern and the factors contributing to its asymmetry. While some acknowledge the commonality of diffraction patterns, others are intrigued by the specific characteristics of the pattern described.

Contextual Notes

The discussion highlights the importance of specific experimental conditions, such as the dimensions and arrangement of the slit, in influencing the resulting diffraction pattern. However, there are unresolved aspects regarding the exact nature of the observed asymmetry and its implications.

Who May Find This Useful

This discussion may be of interest to those studying optics, particularly in the context of diffraction phenomena, as well as individuals experimenting with laser setups and diffraction patterns.

azdavesoul
http://asymmetricphotons.davehewitt.com/__oneclick_uploads/2012/03/asymm.JPG

While playing with lasers in a simple home setup, I have produced asymmetrical diffraction patterns and have been unable to locate explanations in the public domain. By using a green led laser and two parallel panels to create a .5 mm single slit I got a normal diffraction pattern. Then moving one panel 1 cm closer to the laser source while maintaining the .5 mm gap, I got a pattern that changed from narrow bands on one side with progressively larger and wider spaced bands on the other extreme.

Is this new and interesting or have multiple physics students been playing with these patterns for years without bothering to publish.
 
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Sorry, but this is nothing new. You will get a diffraction pattern even from a single edge. The fringe spacing depends on the wavelength and the distance to the screen- which is different for your two edges.
 
I understand that, what struck me as hard to understand is that the pattern was progressive. It varies from thin to thick. Is this just a example of a ‘wave’ pattern where each band is affected by both edges?
 
Here is a clearer pattern and the setup I used.
http://asymmetricphotons.davehewitt.com/__oneclick_uploads/2012/03/asymetric1.jpg

http://asymmetricphotons.davehewitt.com/__oneclick_uploads/2012/03/setup.jpg
 
Last edited by a moderator:
The pattern will depend, entirely, on the details of the diffracting shape involved. What is the actual shape and setup? (not a picture of the equipment but a diagram of the 'slot' or whatever). Remember, the slot depth is relevant as well as the basic width dimension. The simple formula is for a slot in an infinitely thin sheet. In general, the pattern will never be just symmetrical.
 
Sophiecentaur,
The light source is a green led laser, 532 nm.
The target is a paper grid, ruled at 1 cm, 5 meters from the slit
The slit consists of two aluminum panels, .2 mm thick, painted flat black, perpendicular to the laser beam.
The panel on the left side is 1 cm closer to the laser.
 

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