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Thread: NICHIA NDB7875 520nm 1W GREEN BEAM CORRECTION

  1. #1
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    Default NICHIA NDB7875 520nm 1W GREEN BEAM CORRECTION

    Hi!
    Just trying to correct Nichia 520nm 1W with anamorphic prism, G2 on Aixiz module (@300mw, not heatsink yet)

    The results:

    Uncorrected: Output 5x2mm----22x3mm @5,30mts so 3,20mrad divergence
    Corrected: Output 5x5mm----9x3mm @5,30mts so 0,75mrad divergence pretty good!

    So IMO a good option with prisms. No power test losses yet, still waiting for my power meter!

    all the best
    Attached Thumbnails Attached Thumbnails Screen Shot 2014-05-23 at 10.59.45.png  

    Screen Shot 2014-05-23 at 10.59.59.png  


  2. #2
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    Quote Originally Posted by jors View Post
    Hi!
    Just trying to correct Nichia 520nm 1W with anamorphic prism, G2 on Aixiz module (@300mw, not heatsink yet)

    The results:

    Uncorrected: Output 5x2mm----22x3mm @5,30mts so 3,20mrad divergence
    Corrected: Output 5x5mm----9x3mm @5,30mts so 0,75mrad divergence pretty good!

    So IMO a good option with prisms. No power test losses yet, still waiting for my power meter!

    all the best
    I have been wondering about this. But the diodes are just a little too expensive for me to get one to "test" out.

    THanks for the update.

  3. #3
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    I think your losses would be considerable, with such "aggressive" correction, but only a power measurement will let us know

    can you increase the projection distance (use a mirror if you have to) and calculate divergence using measurements from say 2meters away and 10meters away?
    like "2m from output xmm x xmm, 10meters from output ymm x ymm). This will yield more reliable results

    this calculator allows for such data entry http://www.pseudonomen.com/lasers/ca...alculator.html

    also, keep in mind that divergence increases with current, as this is a multimode diode and more emmiters will activate with more current
    "its called character briggs..."

  4. #4
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    actually that is not real good. you should be able to do the same as the 1w blues with these. try using cyl lens I think you will find better results. Also, if you don't mind loosing some power, use a 3x telescope and let the scanners clip the beam. I do this with the blues and I get 2mm on the wall at 15' (3M?). I had an idea to get more on the scanner but I never tried it. If you use some bounce mirrors inside the projector to lengthen the distance to the scanners, you should be able to fit more on the scanners. Do expect to loose 30-50% of the beam doing it my way. side benefit is it also cleans the beam because you only get the core of the diode.

  5. #5
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    Interesting !!! Thanx for posting ! I expect we will need SOME adaptive optics on his LD...in addition to the collimation lens. Yes...the angle on your first Anamorphic looks a bit severe....and this WILL get into our knickers with a PO loss. MMMmmm.. Likely Cylindericals will be demanded!! Too bad...Anamorphics are less demanding to set the position.
    When you get your meter...you will see...for as you rotate the first Anamorphic....you will achieve a lower divergence....but....also....a lower power output !! Optics are just a PITA. CDBEAM=======>
    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
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  6. #6
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    Thanks all for your coments! I'll test power once received LPM

  7. #7
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    You should really test with cylinder lenses. I am pretty sure they will work well, but because you are one of the first to work with these diodes it would be very helpful to see a comparison. Optics are fun. The results are sometimes eye opening.

  8. #8
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    I could order some cylindrical from Thorlabs to test, but need help here. No idea what kind of lenses
    Also don't know if I should go on G2 along with cylindricals...
    any tips please?
    thanks!

  9. #9
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    As far as the collimating lens goes, you might ask everybody who has one of these green diodes so far what they're using ..

  10. #10
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    Steve is right about the collimators. These do vary in their performance and if someone has already tested one that is worth a lot. The cylindrical lens pair is easier. Once the beam is established with the collimator in other words you have installed one. Then, just measure the near field beam dimensions and the far field (10M or more) beam dimensions dimensions and decide how much you can afford to expand the near field (scanner limits) to improve the far field. That expansion ratio determines the ratio of the FLs of the cylinder pair. If the "collimated" beam diverges a lot, like the red, Mitsu diodes then the first cylinder (negative) can be a little less powerful to achieve the desired magnification with the second (positive) cylinder. For example, a -25mm cylinder followed by a +100mm cylinder will give a 4 power magnification and a similar reduction in divergence. The ratio will prove to be a little more due to the divergence in the incoming beam, but I expect you will be able to ignore this with these GaN diodes.

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