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Thread: Making a blue laser beam more narrow, where to find more info

  1. #1
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    Default Making a blue laser beam more narrow, where to find more info

    Hi, just got a 150mw blue laser module but the beam gets very large in diameter over a few meters. Anything i can do to make this sharper or more focused? Looking for the correct words to point out what i mean.
    Can this be done with two lenses or is it too difficult?

    Michel.

  2. #2
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    What kind of module is it, 445 or 473 ? What brand ?
    Maybe your module is simply out of focus, and you should adjust it to project a parallel beam.

    Otherwise...
    There is this thing called "beam parameter product" that dictates that you can convert a beam using optics to have a small diameter with a high divergence or a large diameter with a small divergence, not both !

  3. #3
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    448nm 150mw
    brand, don't think it is a branded module, got it el cheapo, looks like home made module, normally they aren't that bad but have to screw it open to peek inside, will do that tomorrow or so.

  4. #4
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    maybe you can get away very cheap by adjusting the focus of aspheric lens that sits in front of the diode

    next step would be to change this lens to a higher quality one. if you want a narrow beam go for a short focal length

    then, there is a combination of lenses that can be used to shrink the beam but increase the divergence. an example can be found in andy_con's quad builts

    as a nice guy from edmund optics told me "The basic principle of expanders is down to the ratios of the focal lengths of the optics. At its simplest a beam expander consists of a PCX or Achromatic lens at one end and a PCV lens at the other. The ratio of the focal lengths is thus the expander power. When you use an expander in it's conventional fasion, the expansion power also reduces the divergence by that amount, however if you run it backwards (beam reduction) your divergence increases by the expander power and so it is a lot harder to focus to a smaller spot when reducing the beam."

    here is a link, hope this helps http://www.edmundoptics.com/technica...ders/?&viewall

    just as an example, two product codes to construct a 3:1 telescope (pass the beam through it one way and the beam expands, flip it over and the beam shrinks, just don't forget divergence) nt47-911 and NT47-348. these are the lenses that andy_con used



    I sure hope you do get away with just a lens focus adjustment

  5. #5
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    thanks for the feedback and the interesting link, will hopefully have some time this weekend to peek inside the moduel and see if i can adjust a lens without damaging it and turning it to shit. Never openend one up so far, bit chicken
    well there is a first time for everything.



    crazy icons

  6. #6
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    Default laser

    Quote Originally Posted by michelrietveld View Post
    Hi, just got a 150mw blue laser module but the beam gets very large in diameter over a few meters. Anything i can do to make this sharper or more focused? Looking for the correct words to point out what i mean.
    Can this be done with two lenses or is it too difficult?

    Michel.
    where did you get it from ? got a pic of it?

  7. #7
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    apparently someone created this himself and put it up for sale
    The laserdiode is multimode, the divergence is in 1 of the axis lager.
    The spot is more the figure of a line now. Divergence is about 5 mrad wide and 1 mrad long. Perhaps i can use the housing etc for better diode.

  8. #8
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    We will fix it at the LEM

  9. #9
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    Quote Originally Posted by LaNeK779 View Post
    maybe you can get away very cheap by adjusting the focus of aspheric lens that sits in front of the diode

    next step would be to change this lens to a higher quality one. if you want a narrow beam go for a short focal length

    then, there is a combination of lenses that can be used to shrink the beam but increase the divergence. an example can be found in andy_con's quad builts

    as a nice guy from edmund optics told me "The basic principle of expanders is down to the ratios of the focal lengths of the optics. At its simplest a beam expander consists of a PCX or Achromatic lens at one end and a PCV lens at the other. The ratio of the focal lengths is thus the expander power. When you use an expander in it's conventional fasion, the expansion power also reduces the divergence by that amount, however if you run it backwards (beam reduction) your divergence increases by the expander power and so it is a lot harder to focus to a smaller spot when reducing the beam."

    here is a link, hope this helps http://www.edmundoptics.com/technica...ders/?&viewall

    just as an example, two product codes to construct a 3:1 telescope (pass the beam through it one way and the beam expands, flip it over and the beam shrinks, just don't forget divergence) nt47-911 and NT47-348. these are the lenses that andy_con used



    I sure hope you do get away with just a lens focus adjustment

    Thanks for the link LaNeK779

    That was a nice bit of education.

    Thanks
    Kit

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