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Thread: Cylinder lens and Ar mirror problem.

  1. #1
    Join Date
    Feb 2008
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    Lightbulb Cylinder lens and Ar mirror problem.

    Dear friend,


    After the 520nm green module, I use the laser mirror degree 45, but the light power is too loses. The module output light is 530mw, but the after mirror only 445mw.
    this mirror:
    http://www.lasershop.de/Laseroptik/L...gel-LS-15.html
    I tried other mirrors, but the losses is similar (10-15mw difference)

    The red module (oclaro 638 nm diode) without cylinder lens, the light is 720 mW, But the after cylinder lens light only 394 mW.

    What is the typical losses? what is your experience on the optics light loses? How to reduce the light loses?

    Thank you

  2. #2
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    This is a very cheap mirror, you should try a better one, with dielectric layer for about 99% reflection at a given wavelenght.
    Where are those cyl lenses coming from? Provider? Typical is about -5% loss or less on cyl pair if a good AR broadband coating is present on both faces.

  3. #3
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    I thought these were good mirrors, but the loss is very big on this mirrors. I don't bought a lens pair, the cylinders was in the factory module.

  4. #4
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    So, I found the older mirror from Dave lasershow parts and I compared the Lasershop mirror
    Very big the reflection difference.
    Attached Thumbnails Attached Thumbnails Medialas tükör.jpg  

    Dave_Lasershowparts.jpg  


  5. #5
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    Yes, Dave have excellent optics. You can also purchase good cyl pair from him.

  6. #6
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    The mirror and the dichroic loses is resolved, but what about the Pt-30k scanner?
    I measured the light before and after that.(green 520nm)
    Is it good? The scanner mirror is was a center positions.
    Before: 532mw
    After: 474mw

    (Red 638nm: Before: 727mW, After: 576mw)
    Attached Thumbnails Attached Thumbnails Before.jpg  

    after.jpg  

    Last edited by whiteg; 10-04-2017 at 07:28.

  7. #7
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    Well, it could be better...but yes, it is usual on such cheap scanners. Datasheet on these scanners is supposed to be 97% reflection 400-700nm, so about -3% loss on each mirror.
    You get bit more than -5% loss each mirror.
    -3% loss is a 'perfect' scenario with a very ultra-clean mirror, not on real world. Also take into account chinese data-sheets are usually over-speced.
    More over, scanner usually clips part of the glow surrounding beam core. Such glow-clipping can decrease meter reading by -5% or more (depending on beam size and scanner aperture).
    All these variables add that extra -2% loss you get on each mirror.

  8. #8
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    Thanks Jors the informations. I thought, the all optics losses max 40-60 mw and I to underestimate the optical losses and I see the module light power is never same as the projector real output.

  9. #9
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    With amount of power you got 50mw on the high end in most likely not even noticed when lost. The eye saturates. Beyond that it takes tremendous changes for your eye to see the difference. That said it speaks to why it pays to get good scanners with quality mirrors and why I've stuck to Cambridge and pangolin scanners. Maybe you can install the mirrors from the pangolin 506 series on your scanners. It really makes a difference if you are using 445nm. Some scanner mirrors the 445nm passes right through!

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