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B Focusing a laser pointer

  1. May 4, 2017 #1
    I have a green laser pointer. I assume that the beam is nearly focused a infinity because it does not spread much when shown on a wall. My question is, can I use a lens to focus the beam to a smaller spot.
    when I see videos about burning laser pointers I do not see any of them using a lens to focus the beam to a smaller dot.Why not?
     
  2. jcsd
  3. May 4, 2017 #2

    BvU

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    Strange question :rolleyes:. Why not try it first and see what happens ?
     
  4. May 4, 2017 #3
    I did try it. The green spot is so bright it is hard to see if the spot focuses down to a smaller spot.
    It is blindingly bright. Even sun glasses don't help much and then there is the area around the spot that is sort of fuzzy.
    I know, get a welders helmet, right?
    I think it should focus.
     
  5. May 4, 2017 #4

    russ_watters

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    You might try eclipse glasses.
     
  6. May 4, 2017 #5

    BvU

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    or with two polaroids at close to right angle
     
  7. May 4, 2017 #6
    It didn't seem to focus :-( I did use cross poloroid glasses. At least not to a good point.
     
  8. May 4, 2017 #7

    BvU

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    With a convex lens it surely diverges after the focal point, so yes, it focuses. Play around with two lenses but be very careful not to go blind. You wouldn't be the first one with several blind spots.
     
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