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Thread: best collimating lens

  1. #1
    Join Date
    Dec 2008
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    veenwouden
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    Default best collimating lens

    I read that andythemechanic used this lens to collimate his blue diode:

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

    To get the best beam you could variate with the FL or with the NA.

    I wondered what would be the best collimating lens to get the tightest beam with the lowest divergence.

    Option 1: Lens with the lowest FL and highest NA

    Option 2: Lens with highest FL and highest NA

    Option 3: Lens with lowest FL and lowest NA

    Option 4 Lens with highest FL and lowest NA

    Mccarrot and andy both suggested option 2 but i think option 1. What do you think?

  2. #2
    Join Date
    Nov 2007
    Location
    Hungary
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    40

    Default Focus lenght and NA

    The NA must be all times highest value if u want rounded beam.
    The best NA value is arround 0.8
    The lowest NA using on barcode line laser generator optic.

    About the Focus lenght :
    If u have low value focus lenght u will get bigger divergence but on the aperuture will smaller diameter beam.

    If u use longer focus lenght u will get better divergence but the beam diameter will be bigger on apperture.

    So the focuse lenght choosing is depense what beam diameter u need on what divergence

    This is not secret.

    Tom

  3. #3
    Join Date
    Dec 2008
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    Default

    Thanks tomeeii

    Its not a secret but i dont think all members know how to pick the right lenses. You,re explanation makes it allot easier!!! Thanks!!!

  4. #4
    Join Date
    Apr 2008
    Location
    Amsterdam, NL
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    2,098

    Default

    Quote Originally Posted by edison View Post
    Option 1: Lens with the lowest FL and highest NA

    Option 2: Lens with highest FL and highest NA

    Option 3: Lens with lowest FL and lowest NA

    Option 4 Lens with highest FL and lowest NA

    Mccarrot and andy both suggested option 2 but i think option 1. What do you think?
    You forget to tell the whole story

    For a quad or dual setup I find option 1 the best, else you end up with a fat beam

    If you use a multi diode setup with a telescope I think option 2 is the best because its makes stacking easier and after shrinking the beam with the telescope you end up with reasonably divergence.

    My lenses on my webshop got a fl 4,6, so best of both worlds.

  5. #5
    Join Date
    Dec 2008
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    Default

    doesn,t matter now i at least know wich is needed in a quad and wich in a multi setup.

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