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Thread: Efficiency of a Tricho ?

  1. #1
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    Default Efficiency of a Tricho ?

    Hi Folks,

    I'm wondering how efficient a Trichro is when combining RGB and if it's really wavelength specific ? I.E passes more 632.8 than 650 nM...
    If you combine a 50 mW green DPSS 532 with say a 200 mW MaXyz @ 650 nM and a 150 mW blue DPSS at say 476 nM are you going to read the combind power or do you suffer losses and if so how much ?

    Rick
    Profile Redacted by Admin @ 04.24.2010

  2. #2
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    Hi Rick...

    Yes.. All powers will add-up , minus maybe 5 to 20 percent depending
    on the size of the Trichro/Dichro.
    The bigger..the more loss you will have.

    I have one here about a foot in diameter..Its HUGE.

    Just be real careful of backreflections as I believe the coatings
    are broadband.
    And were originally made to work the other way around, of course.

    But they do work in a pinch rather well..!!!

    We have been using about 30mW of green with our 200 reds.
    and about 50mw of blue (its all we have at the moment)..

    Most of all ...Good luck and have fun
    "My signature has been taken, so Insert another here"
    http://repairfaq.ece.drexel.edu/sam/laserfaq.htm
    *^_^* aka PhiloUHF

  3. #3
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    Tks Marconi,

    Now I wonder , which is the best method of combining RGB If you want small beam size , low beam aberations to run through a set of galvos for projection.

    What I have seen used are 2 Dichroic filters ( both pass green and one reflects red while the other reflects blue).
    This only requires 2 adjustable filter mounts and a small area to mount your DPSS lasers and projector head . Good quality filters expect about 10% to 15% loss on total power, about the same as using a PCAOM but you don't have to worry about polarization problems.

    Are pellicle type filters better ?

    Rick
    Profile Redacted by Admin @ 04.24.2010

  4. #4
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    [quote Are pellicle type filters better ? Rick[/quote]

    I tend to believe they are..as they are thinner (less glass)
    there-for less loss.. but setup is about as time consuming.

    The Trichro's are probably easier to find tho..
    There are many old 3ccd camera's out there..
    that have been de-commissioned and...can be got cheap!!
    As far as aberations is concerned.. I didnt notice any..

    I guess it depends also on how much power you want to throw at it too..
    I am guessing the trichro's are great for low power installations
    like say up to a watt...after that I dunno..I have not experienced
    using them above that...
    Spec has more experience using these than I do for full color..
    I never have the time to finish our set-up..
    It's always apart..testing each laser in it before they leave.

    I have used the dichro's at 2watts ..so I know that works ok..

    If you want a cheap solution, Yes the trichro is a way to go..
    But I prefer the seperate dichro solution..
    Plus..backreflections will be at a minimum too!!
    And thats a good thing

    OBTW Rick... Glad to see you here.,
    It just dawned on me ,You have one of our units..hehe.
    WELCOME ABOARD !!!
    "My signature has been taken, so Insert another here"
    http://repairfaq.ece.drexel.edu/sam/laserfaq.htm
    *^_^* aka PhiloUHF

  5. #5
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    Tks for the information Marconi,

    I just finished piggybacking your MAXyz 150 mW module to my Lambda-Pro 532 laser using a dichro filter and custom mount to squeeze it in my ILDA projector. Tested fine although color balance needs tweeking .

    Blue is next If I can sell/trade some of my goodies posted in the Buy/Sell/Trade forum.

    Rick
    Profile Redacted by Admin @ 04.24.2010

  6. #6
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    Hi Rick;

    I've been using one of the Fujinon trichros for quite a while to mix 488 nm Argon with 532nm DPSS and 633nm HeNe... Granted, we're talking less than 100 mw total power here, but the results are quite good. Beam quality does not suffer at all, and the back-reflection problem is not nearly as bad as you might think. (But there *is* some power lost there...) I haven't done any measurements to check power levels going in and coming out of the trichro, but if I get some time this weekend to play with my equipment I'll have a look.

    As for getting the beams aligned to the galvos - no problem! I've been able to set it up on a table-top, and with less than 15 min of tinkering I can get all three beams to pass through a 2.5 mm hole in the side of one of my old lissajous boxes. (One of the cheap ones that MWK used to sell years ago!)

    Granted, for full-color shows you're going to need both near-field and far-field alignment, which will take more time. Still, Spec managed to align everything on his setup in about 2 hours using a similar trichro...

    Have a look at my gallery pics for some idea of just how "ghetto" my setup used to be, and how clean the beams are. Link:

    Eventually I'm going to build all this into a single projector with a direct injection diode to replace the weak HeNe and my Lasever DPSS green instead of the pointer. But I need to get my AOM's working first, otherwise I won't be able to blank the argon!

    Adam

  7. #7
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    Yeah, Buffo

    I had a look at all the Pics in the galleries and ran across the Trichros which I've never used before. Looks good , but Marconi mentionned back reflections that might interfere with your laser sources if the AR coatings aren't optimal.
    All the same now I can keep my eyes out to acquire a trichro for experimental purposes just to see how well they might perform.
    The next thing is squeezing 3 modulatable lasers into a small enough case with appropriate optics to give me a solid state white light projector that's portable.
    I have Red + green now but I fear not enough room to squeeze in a blue DPSS laser in existing case so back to the drawing board for RGB when that time comes. Gotta sell some of my goodies to reinvest in my quest for RGB.

    Rick
    Profile Redacted by Admin @ 04.24.2010

  8. #8
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    Default

    The trichro's from a 3 LCD projector happen to have the AR coating going
    the right way... I've been using Spec's since they're smaller and cuture, but
    I was thinking of running the projector trichros with some bigger lasers (>2W)
    (expanding to keep power density low) and recollimating though a pinhole
    filter after they've passed through to keep it clean... But too many projects,
    not enough time...

  9. #9
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    Default

    Yep, I should have mentioned the 3 LCD style projector Trichro

    What we need is.. is to find defunct units model numbers and make
    That are suitible for this.

    I did cruise through ebay but was unable to make a decision.

    This might be the answer to making white up cheaply !!
    "My signature has been taken, so Insert another here"
    http://repairfaq.ece.drexel.edu/sam/laserfaq.htm
    *^_^* aka PhiloUHF

  10. #10
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    Well, for what it's worth, I played around with one of my Fujinon triochros this morning. I started with my 10 mw DPSS pointer, and noted about 1 mw of power loss through the trichro. (Using my Coherent Lasercheck.) However, my pointer's ouput tends to drift up and down a bit, so I decided to do some more testing with my Lasever DPSS unit, which is a lot more stable.

    I tried it at several different power levels, up to around 40 mw or so. (Didn't want to go any higher without breaking out the googles and getting rid of all the reflective junk on my workbench!)

    The trichro had consistent losses of between 10 and 12 percent on the green input. Also, almost ALL of the loss is internal to the trichro. I measured the reflected beam from the input face and discovered that it was always 2 orders of magnitude dimmer than the incident beam. (EG: 30 mw in, reflected beam is ~ .3 mw)

    This tells me that the Fujinon trichros have fairly good AR coatings on the input faces (or, at least on the green side), and most of the power loss is due to the internal losses from the prisms inside the unit.

    Later on I'll play around with a few of my HeNe heads and a couple of my Argons to get some more data on the red and blue input faces.

    Adam

    PS: One final thought: The green input face is the one that shoots straight through the unit, so maybe it has an unnaturally easy path wih fewer reflections, and thus has abnormally low losses? I guess I'll know more after I test the red and blue faces...

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