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Thread: Amateur question: reducing danger of specular reflection?

  1. #1

    Default Amateur question: reducing danger of specular reflection?

    Hello,

    I just purchased an inexpensive chinese RGB projector (from eBay). I will be using this projector in a home media room/DJ booth (20' x 20'). The power rating is 380mW total (R:300, G:50, B:30), TTL blanking.

    Now I have a few questions about safety. I plan to have the projector mounted on a 9ft ceiling aimed horizontally. I would also like to have a set of many small mirrors on an opposite wall that will reflect the beam downward parallel to the wall, creating a laser "backdrop". I am assuming that at this power, it will be dangerous if someone were to get a direct beam into the eye, so I would like to make sure that the downward beam reflection is safe. How can I decide what mirrors would diffuse the beam enough to make it safe, I am thinking that if I use low quality (non-first surface) mirrors I can make the beams fairly safe. Any recommendations? maybe a lens or covering on the projector aperture?

    Also, I want to make sure that If I program any beam shows that the projector cannot "accidentally" scan downwards. I was thinking of putting a blocking panel on the lower half of the projector to catch any beams below a certain angle.

    One last thing, do I need to worry about the beams (reflected or not) burning carpet or walls (dark burgundy painted)?

    Thanks!
    JK

  2. #2
    Join Date
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    You could poit the projector downward as you said and limit the projection area with the software that will run it. You would then have an "off limits area" to the general guests. Yes the 300mw of red alone would start something smoking with heat. I would not have static beams with dark colored surfaces. Keep them moving and you should be fine.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  3. #3

    Default

    OK, thanks for the advice on the software "lockdown" of certain areas.

    One other thing, the seller of this projector is offering to add analog blanking instead of TTL for about $750. Is it worth it to go for this?

    I assume that if I go with TTL blanking I have no capability to "dim" the entire projector, if I want to use less power (for safety). Is this the way that blanking works?

    Thanks
    JK

  4. #4
    Join Date
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    Go with analog blanking for sure. Noone uses TTL anymore. Museum technology.
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  5. #5

    Default

    OK, now I just need an idea on whether an additional $750 on a $2000 projector is worth it to get analog blanking?

    Thanks
    John K.

  6. #6
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    For about $2300 you could be set up with DT-40 pro scanners,100mw of 473nm,60mw of 532nm, and 400mw of 660nm. All analog modulation. No enclosure though....just main parts. Plus you would have to wire everything up. Then you would need dichro's and mounts too.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  7. #7
    Join Date
    Jan 2006
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    Hey John;

    $750 is a steep price to pay for analog blanking, especially on a $2000 projector. As much as I am a champion of analog blanking, in your case I don't think it makes sense to spend the extra money. I'd save that cash and use it for your NEXT projector. Assuming that you are relatively handy with a soldering iron, you should be able to build your own RGB projector. (You can use your F2000 unit as a guide.) There's plenty of good information here on PhotonLexicon to help you with the build.

    As MechEng3 mentioned above, you could build a much nicer projector with more power and better color balance (not to mention faster scanners) for about the same cost as you'd end up paying for your current projector with the analog blanking upgrade. But I'd wait until you've gotten familiar with this projector first, before you try to build your own.

    Besides, you can still create some very beautiful effects with TTL color. Granted, analog is superior. However, if this is your first RGB laser, I'm sure you'll be very pleased with it even though it will only make 7 colors. Save your cash and upgrade later, after you've had time to play with this one for a while.

    Adam

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