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Thread: 520nm (diode) vs 532nm (DPSS)

  1. #1
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    Default 520nm (diode) vs 532nm (DPSS)

    Does anyone here own around 3W-5W of both of these, who can comment on better visibility for graphics as a far distance?

    At the 2W region my personal experience for 520nm diode is:
    - Nicely matches beam characteristics of red and blue in a typical 3W - 7W RGB
    - Colors seem to blend better
    - Not quite as "brilliant" of a green

    And 532nm DPSS:
    - Superior beam profile to diode (divergence is better and overall "cleaner")
    - Generally more visible and crisp, especially for graphics where divergence is important
    - Shorter operational life, prone to temp fluctuations

  2. #2
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    Just go full OPSL

    I prefer the modulation of direct diode, but like the beam quality of the 532 DPSS

    Are you talking for use in an RGB projector or standalone?

    Standalone I'd go DPSS for graphics over 520 stacked diodes.

    Once in a RGB projector if divergence matches that will look best ime.
    leading in trailing technology

  3. #3
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    Thanks for your thoughts. Haha yes in a perfect world OPSL.

    My application is single-color graphic projection on distant surfaces (buildings, mountains).
    If one considers bang-for-buck.. Do you reckon 3x 5W DPSS beats 1x 5W OPSL.. especially in a single-color unit where you are able to combine multiple projectors into a single image?

    Quote Originally Posted by polishedball View Post
    Just go full OPSL

    I prefer the modulation of direct diode, but like the beam quality of the 532 DPSS

    Are you talking for use in an RGB projector or standalone?

    Standalone I'd go DPSS for graphics over 520 stacked diodes.

    Once in a RGB projector if divergence matches that will look best ime.

  4. #4
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    In a power range up till 7W i would recommend full diode. Direct diode has a much larger lifespan then DPSS and all 3 colors can be perfect linear with a good quallity driver. A green 2W can be 3.6x5mm at nearfield and 0.7mrd divergence. The red can be a single mode 16 combiner doing 2.7W in 5x5mm at 0.7mrd. The blue can be a 462nm/445nm in same divergence as green. Important is that the beamsize stays below 5mm to allow fast scanning. A nice scanset would be an EMS8000 for your application, a cambridge or a scannermax. In my opinion DPSS is old technology and nice for a lab but not ideal for prpjectors. Back in the day there wasn,t anything else but with direct diode nowadays its the way forward. For red i wouldn,t recommend multimode comlplicated graphics as you need fast scanning and so the beam is simply to big to fit on 5mm mirrors and have 0.7mrd diverence.


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  5. #5
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    If you are projecting on a mountain and not a screen, the color is likely to be all wrong. If it’s dirt it reflects browns if it’s trees it reflects greens. So for dirt you need more blue for trees more red and blue.

    so why do I mention this? In almost all cases the green isn’t the limiting factor. What color is? Red of course our old friend.

    I’d focus more on getting enough red. Now Opsl might really help you if you can afford it. I’d also shift that red to the orange side 638-632 to maximize visibility.

    i have use dpss green with aom and was less than impressed once I took into account the power loss. Direct green will be your friend. A large frame krypton for the red could also be a solution. They can be had for cheap these days but stacking diodes is likely the solution up to 5-6w red.

    i like 532 green better because of the yellow it makes. I like 520 better because it’s cheap and modulates well and lives a long time.

    there is no right answer.

  6. #6
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    In almost all cases the green isn’t the limiting factor. What color is? Red of course our old friend.
    Yep more red is always good to have. In a 7w rgb graphics projector a nice balance would be 2.5/1.8/3.5.

    Red can be a single mode 16 combiner with a dual setup direct green and a dual setup blue. This can be adchieved in 5x5 at nearfield and 0.7mrd at farfield so fast scanning is possible. In the past i did a mix for green in 515nm/530nm and 462/445nm and it it had so rich colors it was amazing. You could do also the single mode red in 8+8 in 638/660nm. That would really be something!

    Anyway i would go for a dual setup blue in 445/462nm. 462nm is so beautuful. I,m currently building a 12W RGB with 2x445nm en 1x462 because i just couldn,t resist to do it . But then again i have all the materials to do what i want and when you need to pay someone to build a customized projector is a different story of course


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  7. #7
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    Quote Originally Posted by edison View Post
    Anyway i would go for a dual setup blue in 445/462nm. 462nm is so beautuful. I,m currently building a 12W RGB with 2x445nm en 1x462 because i just couldn,t resist to do it . But then again i have all the materials to do what i want and when you need to pay someone to build a customized projector is a different story of course
    Nice! For your projector what is the near field beam size, and the corresponding x and y mirror size will you be using to match?

    Quote Originally Posted by edison View Post
    In a power range up till 7W i would recommend full diode.
    Agreed, Thanks for all these rough figures on what is achievable.

    Quote Originally Posted by kecked View Post

    there is no right answer.
    Haha yes I am realising that. Thanks for sharing your wisdom and experience, all good points.
    Last edited by Humphry; 05-10-2020 at 22:52. Reason: typo

  8. #8
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    Nice! For your projector what is the near field beam size, and the corresponding x and y mirror size will you be using to match?
    Ideally i would like to install an EMS8000 with 6mm aperture but i start with a raytrack50 wich i bought from JMlaser. Its bassically a DT50 but i rather pay a bit more knowing that the scanset works flawless. With lasers its either good or bad , nothing in between and i know with my own source , my own designed case and a scanset from Joachim it will be absolute perfect.

    For your application i would recommend an EMS8000 with 5mm aperture or better start with a Raytrack. But l agree with kecked that there is not really a good answer as allot of options are determined how much money you want to spend.


    Johan


    Interested in 6-12W RGB projectors with low divergence? Contact me by PM!

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