Uses for laser light in measuring hair width

  • #1
I have a question that I feel I cannot find enough on.

We just did a practical in Physics class where we used a laser light shined on a single hair strand in order to create a diffraction pattern and use formulae to determine the hair's width. Because of Babinet's principle, the hair managed to cause the laser light to diverge around it and form the diffraction pattern of maximas and minimas on the wall.

Would there be any real life applications for such an experiment? The best I can think of is a forensics use in evidence by matching hair width at a crime scene with those of the suspects. Would there be any actual application?
 

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  • #2
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The best I can think of is a forensics use in evidence by matching hair width at a crime scene with those of the suspects.
That would be better accomplished using a microscope.
 
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  • #3
Yeah, I am aware of better methods in forensics, but I just cannot seem to find an application for using lasers in measuring hair width. Could it be used to measure the thickness of other things?
 
  • #6
sophiecentaur
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That would be better accomplished using a microscope.
In many / most cases, perhaps but there could be many instances where a microscope cannot be brought in close enough or the sample held steady enough. A single photograph of the patterns from several hairs could be easier to obtain. The only extra information needed would be the distance between the sample and the image plane (to get the angles of the fringes).
There are many ways to kill a cat.
 

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