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Thread: Cylindrical lenses are 'go'

  1. #21
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    The Diode has to be rotated correctly, since the cylinder lenses are only to affect the slow axis divergence (expand beam on the slow axis to reduce its divergence). Critical is an on axis placement of the lenses and adjustment of the focal lengths. For this purpose I have developed a miniature adjustable cage mount system for the diode and cylinder lenses. Beyond this I want to try my luck with just 2 convex cylinder lenses to circularize the beam without the aspheric collimator which was the primary reason for developing the cage mount in the first place. And before anyone asks I’m not trying to sell cage mounts.

  2. #22
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    Maybe this should be posted elsewhere in the forum regarding the never ending question, cylinders or prisms? Here my questions and answers with ThorLabs. With these answers I tend to lean towards the cylinder solution. I also ordered a set of plan-convex lens to test collimation without pre aspheric collimation to reduce total number of transitions to pass to 4.


    Questions:
    For circularizing a collimated diode laser beam is there a preference to either cylinder lens or anamorphic prism pairs? Are there differences in loss?

    When individually collimating the fast and slow axis of a Laser diode with plan-convex cylinder lenses, can the resulting divergence of each axis be calculated?

    Hi Frank,
    If you use AR-coated prism pairs or lenses, there will not be a significant difference in losses – you’re passing 4 interfaces either way. Which method is preferable depends on your application: The prism pairs come pre-mounted for certain magnifications are therefore very easy to set up – if you need a magnification that we don’t provide from stock, things become more complicated. We sell the prism pairs unmounted as well, and the angles at which they need to be mounted can easily be computed to achieve an arbitrary magnification – but then suitable mounting has to be provided.
    In the past I have printed CAD drawings of the correct angles on paper and epoxied the prism pairs and the paper on KM100B platform mounts, which works o.k. as long as you mount them horizontally.
    A cylindrical lens pair is more involved to set up than a stock magnification anamorphic prism pair, but since the lenses are available in many focal lengths, it is easier to set up arbitrary magnifications by choosing the correct lenses. Also, if you experience astigmatism when focusing the beam, the distance between the two cylindrical lenses give you an easy to adjust degree of freedom to compensate, whereas with prisms you have 2 angles you would have to adjust.
    Finally, for a diffraction limited Gaussian beam the divergence angle is given by lambda/pi w_0, where lamda is the wavelength of your light and w_0 the 1/e^2 beam waist of the collimated beam. For more involved calculations or to optimize your setup, I would suggest taking a look at OSLO, which is a not-too-complicated optical design software. There is a 30 day trial version available, as well as a version for educational purposes.

    Best regards
    Tobias Paprotta

  3. #23
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    Oct 2006
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    This round will be closing soon!

  4. #24
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    Mar 2007
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    Eindhoven, Netherlands
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    Hi!

    I'd also like 2 lenses! thnx!

  5. #25
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    Hey decix, why did you rate this thread so low?

    it was at 500mW

    THE FIRST GROUP IS NOW CLOSED. THE LENSES HAVE BEEN ORDERED.

    Feel free to post to enter the second round if you missed it.

  6. #26
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    Quote Originally Posted by drlava View Post
    Hey decix, why did you rate this thread so low?

    it was at 500mW

    THE FIRST GROUP IS NOW CLOSED. THE LENSES HAVE BEEN ORDERED.

    Feel free to post to enter the second round if you missed it.
    Hi Dr L

    I paid last night, am I in the first batch?
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwin’s natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  7. #27
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    Oct 2008
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    What do you have used as collimating lenses ?

    Are that the AIXIZ Lenses or different ones or
    are there lenses you do not recommend ?

    Regards,

    Mackel

  8. #28
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    Hey Dr L, I paid before you posted your last update but I am still marked as unpaid
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwin’s natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  9. #29
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    Cleveland, Ohio
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    Quote Originally Posted by mackel View Post
    Are that the AIXIZ Lenses or different ones or
    are there lenses you do not recommend ?
    The aixiz 405-445 lenses have at least 25% losses, 22% losses over a shorter focal length lens. For maximum power I suggest a shorter focal length lens 4-5mm FL.


    Quote Originally Posted by Doc View Post
    Hey Dr L, I paid before you posted your last update but I am still marked as unpaid
    I have updated the list now, yes you are in the first batch. thanks

  10. #30
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    Mackel said your order was included in his set.

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