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Thread: Calculate the cylindrical lens for the blue 445nm

  1. #11
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    I think the best way to tame the beam with an asperic lens with a short focus length like the one from Larry DFW (LPF) and then 1 cylindrical lens to tame the x-as (fast axis)

    Andythemechanic said the otherway arround, here,s the message he send me:

    actually it should be the other way round: The invariance of the beam parameter product dictates that the longer the focal length, and therefore spot diameter, the smaller the divergence. I think the difference between this lens and other lenses with higher focal length, is that this one is aspheric and eliminates spherical aberations, while other lenses are often simple spherical ones that introduce aberations and worsen the beam. So going to high focal length with aspheric lenses should be the way to reduce divergence. Of course you have to retain a high NA of roughly 0.5 to catch the whole beam on the fast axis.

    The lens that andy used was:

    Thorlabs C610TM-A f = 4.0mm 0.60NA Geltech Mounted Asferische Lens

    I would love to try these:

    http://www.thorlabs.de/thorProduct.c...mber=C660TME-A

    Fl= 2.97 NA = 0.60

    Larry,s lens is simelar to the C660TME-A and a lot cheaper. I will try the on fro larry in my 4 setup next week

  2. #12
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    But if you place a single cylinder lens in a collimated beam will it not just turn it into a line?

  3. #13
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    Yeah I think you need two cylinder lenses after the initial collimation if you are trying to correct the fast axis. This would work like a beam expander as Dave stated above, but only on one axis.
    Last edited by MisterWilling; 06-15-2010 at 14:48.

  4. #14
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    You can have the cylindrical lens in front of the collimated diode in two ways. With the rond edge towards the diode and with the flat surface towards the diode. I think the first is the one.

  5. #15
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    Default len

    Just post the part numbers to order from thor.

  6. #16
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    Default lens

    I wonder if you could just split a clear plastic rod in half and use that ?

  7. #17
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    Quote Originally Posted by edison View Post
    You can have the cylindrical lens in front of the collimated diode in two ways. With the rond edge towards the diode and with the flat surface towards the diode. I think the first is the one.
    From what I understand the optimal orientation of a PCX lens will depend if the beam is aready collimated or not, but the result will be more or less the same either way round

  8. #18
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    Quote Originally Posted by p1t8ull View Post
    Stellar work again Dave

    Maybe a GB will be in order to get the optics price down for the much desired small tight beam with these 445's...
    Maybe you missed it but he's repeating my earlier posts.. this is is old news, I'm already having a group buy for lenses.. please see this thread.

    http://www.photonlexicon.com/forums/...ad.php?t=11393

    This group buy will be for the modules with lenses, OR if you just want the lenses. Together we can get the cheapest prices.

  9. #19
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    Quote Originally Posted by drlava View Post
    Maybe you missed it but he's repeating my earlier posts.. this is is old news, I'm already having a group buy for lenses.. please see this thread.

    http://www.photonlexicon.com/forums/...ad.php?t=11393

    This group buy will be for the modules with lenses, OR if you just want the lenses. Together we can get the cheapest prices.
    one thing that makes me not want to join the GB is the use of approximately and probably regarding beam sizes.

    do you have any exact measurements? (ive not read the entire thread)
    Eat Sleep Lase Repeat

  10. #20
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    Yes. One thing to keep in mind is that some people use 50% brightness cutoff to determine beam width, but my measurements use 90-98%. So when someone tells you 3mm beam height and you think ok, great that's an actual value, it's not the whole story.

    With a single module, expect 3.5mm beam height and 1.5mm beam width at aperture. With the dual module, expect 3.5mm x 3.5mm output beam.

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