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Thread: 445nm diode with beam correction optics (anamorphic prism pair)

  1. #1
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    Default 445nm diode with beam correction optics (anamorphic prism pair)

    Hi guys

    I have some very promising results with my setup, from common thinking with djolek

    I'm using a classic collimator, don't want to disclose the lens used now but everyone could figure this themselves as it is really simple

    The beam at the aperture is 2mm*0.5mm and diverges to 20mm*2mm after 6 meters with no correction, but the lens I use gives almost no speckle and the beam is very clean

    I use an anamorphic prism pair from an old crystalaser unit Gogu sold me some time ago, which is coated for 808nm and thus losses are important, but it is not really important as cost per mW is 0.04 euro

    Here are some pictures, the beam at 6 meters is now 1cm*1.5cm which gives a divergence of 1.5mrad... not so bad and I'll settle with that setup as it is very pleasant


    a view on the anamorphic prism pair

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    a beam shot, a bit blurry cause the camera is hard to focus

    Click image for larger version. 

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    a beam shot with a bit of cigarette smoke, really outstanding color as soon as you have a bit of smoke

    Click image for larger version. 

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    and finally the spot shape at 6 meters, clearly nice for a two cent setup

    Click image for larger version. 

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  2. #2
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    hmm it seems it's your side, cause they are attached like any other picture I've uploaded and are displaying fine here..

  3. #3
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    seems there are forum problems as I answered your message and it displays before it

  4. #4
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    Oop's.... Can't see any pictures at all, not even links.

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  5. #5
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    Is it right that I see that you use the prism pair to expand the beam along the slow axis.
    How come the fast axis, not being corrected, goes down from 20mm to 15 mm at 6 meters?

    Have you tried to shrink the beam on the fast axis with the prism pair? I'm wondering if that has any good results, or will divergence still be out of control?

  6. #6
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    this is quite simple

    my prism pair has a 4:1 ratio

    I expand the fast axis which is 0.5mm wide before the prism pair, this gives me a 2mm width with 1/4th the divergence, which is now almost identical to the divergence of the slow axis

  7. #7
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    Hi, jumping on that, I found that stock module, do you think it is worth a try to get it going with a 445nM diode?
    Attached Thumbnails Attached Thumbnails IMG_6095.jpg  

    IMG_6096.jpg  

    IMG_6101.jpg  

    IMG_6100.jpg  


  8. #8
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    I think so, but you'll have to adjust prisms to put the first at brewster's angle for that wavelength

    my tests are continuing, by stacking two beams with the knife edging method I have a beam of 2*1.5cm at 8 meters, same 1.5-ish millirads

  9. #9
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    Thank you, I'll play with that.

  10. #10
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    Quote Originally Posted by shrad View Post
    this is quite simple

    my prism pair has a 4:1 ratio

    I expand the fast axis which is 0.5mm wide before the prism pair, this gives me a 2mm width with 1/4th the divergence, which is now almost identical to the divergence of the slow axis
    that makes sense, thanks, looking forward to trying it myself.

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