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Thread: IR Leakage? (Bigdipper F-2000+ (RGB))

  1. #1
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    Default IR Leakage? (Bigdipper F-2000+ (RGB))

    I recently acquired my first inexpensive RGB projector and am wondering if the manufacture of the laser modules put an IR filter on either the green or blue heads.

    I'm not entirely sure how to tell if there is IR present as I do not have a power meter - but as a crude method I used my Sony video camera, both with and without "nightshot" while covering up the IR LED emitter.

    In normal viewing everything looks good. Switching to nightshot reveals the entire inside of the case glowing bright.

    So my question is really - is it possible to tell just using such a method?


    My next question is, can excessive IR give one a really bad headache? (in the psychical sense) or could it be caused by the slow scan rate and flickering? (had one last night).

    ---------------

    Let's say for a minute there are filters - what would happen if a second filter were used? Other than a slight loss of visible light.



    Anyone know where I can locate a couple of filters (other than Spectra Physics or Edmund), or perhaps know the part number of the item I'm looking for...

    It contains (1) 50mW 473nm module and (1) 50mW 532nm module. Reds are not a concern as they are 650nm diodes (2) 150mW.


    Thank you in advance for the replies!



    Phil

  2. #2
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    Cool

    I have a buddy that has the F-2000 unit from Big Dipper. It does not have IR filters on either of the DPSS lasers, and it puts out around a half watt of IR along with all the visible light.

    Will it give you a headache? No, not unless you've been scanning the beam across your eyes. (Remember that the IR will diverge a *lot* more than the visible light will, so you'll have IR all around the pattern that you actually see. Don't get too close!) If you weren't viewing the beam head-on, then it's likely you just had a headache last night. Flickering images can also cause eye strain, which can lead to a headache.

    As to whether the Sony camera will work to detect IR, I would say "probably", though I've never actually tried it. But given what I've heard about Big Dipper units not having IR filters, I'd say that your results are pretty definitive.

    If you put an IR filter in the beam path (prior to the scanners), you should be able to remove nearly all the IR from the output. And yes, you will likely loose a little bit of output - but it shouldn't be much. (couple percent) This is exactly what my buddy ended up doing to kill the IR in the output on his unit.

    As far as a source for an IR filter - If you don't want to deal with Edmunds, you might try OneStopLaserShop.com. Or you could check with Bridge here on PhotonLexicon. He may have something that will work for you. I even found one on E-bay a few years back, but that's hit-or-miss.

    Adam

  3. #3
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    Default

    Wow, thanks Adam. I will check with both sources for the IR filtering.

    While I am aware of the divergence of IR with these units, it still isn't all that healthy in my opinion to have scattered around.

    There seems to be enough room to mount something between the last dichro and the scanners. I think a screw and a piece of "L" bracket with a dab of epoxy will do just fine for the mount.


    Thanks again for the quick reply!


    Phil

  4. #4
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    In regards to the headaches, I have noticed that i will get them if I look in the general direction of the laser source or if staring at the spot on the wall for long. The lasers don't even have to be all that bright. I think that some people are just more sensitive to bright lights than others. Beam shows are a no-no for me. But, I can look at shows on the wall just fine.

  5. #5
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    Depending on the configuration of the projector the IR in the output may well be of negligable value to worry about. The Dichros will be good (hopefully) at their job and if you think about the lasers that are hitting the relevant dichros you may find that its lost before it gets near the scanners.
    In my projector - which is unconventional in layout so say the least - the blue at the back has no filter but goes first through a pass blue bounce green filter, then a pass blue/green reflect red. I know I loose quite a bit of the ir in the first filter - its bounced away from the beam path at 90 degrees - but even ignoring this when the beam hits the red bounce filter anything thats in there thats remotley red (about 99 and some %) will disappear towards my housing and away from the scanners. Plus any ir getting to the scanners will be diminished even more if you have dielectric mirrors on the scanners as these are often poor at red performance.
    Trust me if the layout is right you DO NOT need to worry about IR in the output.

    Rob
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  6. #6
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    Thanks again for the replies.

    I have another question. The interface for hooking up a computer is an 8-pin RJ45 plug.

    1) B+
    2) X
    3) B-
    4) Y
    5) R+
    6) G+
    7) R-
    8) G-

    What do I use for the scanners? I've got two wires! X and Y. Do I use the case ground or should I just run some new wires from the scanner amplifier?


    Thanks,

    Phil




    *edit* I found this from 2006 on the forum - http://www.photonlexicon.com/forums/...hp?t-1542.html - I believe this is the same model. So I read and found that many of you just ran the additional wires to the DB-25 connector as opposed to dealing with the RJ45 plug.

    I'm going to have to break down and buy some software soon! Do I get the Beam whole house vaccuum or purchase Pangolin?!
    Last edited by godfrey; 03-09-2008 at 19:28.

  7. #7
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    Cool

    Quote Originally Posted by stanwax View Post
    Depending on the configuration of the projector the IR in the output may well be of negligable value to worry about.
    Dream Beamz has one of these projectors. It's got a 50 mw dpss green, 50 mw dpss blue, and a pair of 150 mw red diodes combined with a PBS cube. None of the DPSS lasers have IR filters.

    We checked the output with and without an IR filter, and discovered that the thing puts out nearly a half watt of IR! So you need to be careful if you own one of these. (George added a filter to the beam path before the scanners to kill the IR in his unit.)

    Unless Big Dipper has made significant changes to the F2000 projector design since late 2006 (when George bought his), then there certainly is a lot of IR to worry about in the output.

    Adam

  8. #8
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    Quote Originally Posted by buffo View Post
    Dream Beamz has one of these projectors. It's got a 50 mw dpss green, 50 mw dpss blue, and a pair of 150 mw red diodes combined with a PBS cube. None of the DPSS lasers have IR filters.

    We checked the output with and without an IR filter, and discovered that the thing puts out nearly a half watt of IR! So you need to be careful if you own one of these. (George added a filter to the beam path before the scanners to kill the IR in his unit.)

    Unless Big Dipper has made significant changes to the F2000 projector design since late 2006 (when George bought his), then there certainly is a lot of IR to worry about in the output.

    Adam

    This was purchased around the same time (in 2006) - I purchased this model a week or so ago from a member of the forum.

    I guess I don't get it...why go through all the trouble of designing a module and decide NOT to put a filter on it...


    Thanks Adam!


    Phil

  9. #9
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    Quote Originally Posted by godfrey View Post
    This was purchased around the same time (in 2006) - I purchased this model a week or so ago from a member of the forum.

    I guess I don't get it...why go through all the trouble of designing a module and decide NOT to put a filter on it...


    Thanks Adam!


    Phil
    Omitting the IR filter makes your laser look like it has a higher output and is criminal in my view. If you don't know any better and have no way of directly measuring, you're being duped.
    Profile Redacted by Admin @ 04.24.2010

  10. #10
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    Default

    big dipper has always been honest about visible output. If you are getting a 400mw RGB you are getting a 400mw visible RGB. Unfortunately most of the lower end manufactures really dont understand why you would need an IR filter.

    Anyhow, here is the pinout diagram I threw together years ago. The X and Y get their ground from the rgb negatives. Not the most efficient design. And you would just need to open it up and hard wire everything on it instead of using the rj45 connector for some dacs


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