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Thread: Interesting Layout

  1. #1
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    Default Interesting Layout

    Just kinda noticed that the folks over at LaserFreak forum, have some very interesting layouts to thier projectors. Seems they are not using 45 degree dichro's, I wonder how much benefit there is to doing this:




  2. #2
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    That's a way of getting the heights of the lasers to match us with 2 mirrors instead of one.
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  3. #3
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    That's not really what I'm refering to. Its where the beams come together on the bench are at very unique angles prior to going to the scan head.

  4. #4
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    Dichros are not exclusively optimized for 45-degree (mechanical) operation. Some are actually optimized for the "zero angle". In fact, in my own projector that uses a HeNe and Argon, I use a dicrho with nearly zero-angle incidence. There could be some throughput benefit, depending on the dichro. (In my case, there is.)

    Now, with that having been said, that may not be the reason why those particular projectors used non-45-degree arrangement. It could be space reasons or even ignorance...

    With non-45-degree incidence, polarization becomes much more tricky. In my case, I was able to rotate the (round) HeNe to optimize the polarization. That's not easy with square lasers that have mounting flanges...

    Lesson (whether it applies here or not): Just because someone else does something, doesn't mean that even they know the consequences!! Don't assume that if someone does something different from you, that they are necessarily smarter than you. After all, how many times was the (extremely poorly designed) Laser Media LM22SDA Scanner amp duplicated by people who thought that surely, Laser Media must know what they are doing?

    Best regards,

    William Benner

  5. #5
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    I see one apparent drawback with this setup. They're adding the blue light first, with an extra mirror. Since every mirror represents a small loss you'd want to add blue last like is typically done in our 45 setups. Assuming that 5% is lost on every mirror (which might be a bit high) you'd end effectively up turning that 100 mW blue into a 86 mW, and that's before the galvo mirrors!

  6. #6
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    A lot of the guys at the Laserfreak forum are using dichros optimized for 22.5 degrees. I believe it was HB laserkomponenten that sold these.
    In my projector I chose to add red as the last color because it has the lowest brightness. Although blue is more expensive per mW, adding red last gives the most balanced white output in my case. Here this person might have had the same line of reasoning.

  7. #7
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    Default LM22SDA

    Quote Originally Posted by Pangolin View Post
    After all, how many times was the (extremely poorly designed) Laser Media LM22SDA Scanner amp duplicated by people who thought that surely, Laser Media must know what they are doing?

    Best regards,

    William Benner

    Hey Bill,

    Whats so bad about these Laser Media Amps? I have two projectors
    that still use these amps. What should I look out for as so, I don't damage the G120D's?

    Thanks,

    Mark

  8. #8
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    The Edmund Optics blue dichro I have is absolutely pants at 45 degrees. Put it close to 90 to the beam and its brilliant with very little transmission. In contrast their red dichro is mega at 45 - but get it a little off and you loose power.
    Hopefully this week I will be doing some real testing of the dichros I have from Bridge at laserwave. In initial tests it is very clear they transmit much less than EO ones (of the colour they are supposed to reflect) and they are extremely insensitve to angle.

    Rob
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  9. #9
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    Quote Originally Posted by ImageLight View Post
    Hey Bill,

    Whats so bad about these Laser Media Amps? I have two projectors
    that still use these amps. What should I look out for as so, I don't damage the G120D's?

    Thanks,

    Mark
    The LM22SDA is probably the worst amp ever made for G-120s. There are lots of problems with that design. One problem is that the position demodulator is only single ended, and also, the way they did it, if you key-up a walkie talkie or even bring a cell phone anywhere near those amps, it will drive the scanners crazy.

    Another thing -- there is no current limit inherent in that design. On the G-120, if you drive more than 2.25 amps peak current into that scanner, you will demagnetize it (eventually).

    There have been many a demagnetized G-120s, and also many shorted position diode rings that resulted from the LM22SDA. It's basically a scanner killer. (Not to mention, you barely get 12K out of these amps...)

    Best regards,

    William Benner

  10. #10
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    I think this setup is the best..
    Quick and simple..
    And you can adjust the height on each laser with just one mirror !
    This is the setup I use now : (see attachment)
    Attached Thumbnails Attached Thumbnails MediaLas_beam-alignment.jpg  


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