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Thread: Big red

  1. #1
    Join Date
    May 2006
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    Norway, Fauske
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    1,206

    Default Big red

    Hi,

    look at the pictures:
    Big red beam


    Close up at red...shows 3 small beams?


    red and green. Red is all over the green (and blue)


    Is it suppose to be like this? Big fat red beam?

    Got also this problem with red (red line)

    How can I fix this? Have tried to clean mirrors with acetone+ alcohol 1:1
    Still there...

  2. #2
    Join Date
    Feb 2005
    Location
    Florida
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    802

    Default

    HI Cruch..
    Could be a couple of things...

    It may be that this laser uses several diode chips side-by-side on the same
    diode mount to acheive the higher powers ..or
    The diode (if it is a single unit) may have suffered facet damage...hence a stripe pattern.
    But it really looks like several stacked in there to me..

    Because of the stacking , you will have a wider beam..yuck
    that makes it tuff to use with small mirrors.
    But thats how some manufacturers do it..to get high power red.

    Perhaps you could get us a picture of the spot the beam makes
    could help answer that.

    Good luck with it.
    "My signature has been taken, so Insert another here"
    http://repairfaq.ece.drexel.edu/sam/laserfaq.htm
    *^_^* aka PhiloUHF

  3. #3
    Join Date
    Apr 2006
    Location
    Caracas, Venezuela
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    210

    Default

    Looks to me like the red is not TEMoo. If that's the case, I don't think you can do much about it. Perhaps turn the power a bit down?.
    Remember the future?, That'd today, as you imagined it yesterday.

  4. #4
    Join Date
    Nov 2005
    Location
    Melbourne, Australia
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    Default

    What can you do to fiux the big beam? Replace the 635nm with a laser with better beam data.

    Solution, replace the red for something with better beam data.

    My recommendation would be an Arctos red
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  5. #5
    Join Date
    Oct 2006
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    Central Florida
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    Default

    Damn... That is a wide ass beam. Is there no way to focus it better? Would a lense be cheaper than a new laser?
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  6. #6
    Join Date
    Nov 2005
    Location
    Melbourne, Australia
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    Default

    Quote Originally Posted by allthatwhichis
    Damn... That is a wide ass beam. Is there no way to focus it better? Would a lense be cheaper than a new laser?
    A smaller beam size will lead to higher divergence. there isnt anything you can do with the big stripe 635nm's except live with the poor beam quality
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  7. #7
    Join Date
    Oct 2006
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    Central Florida
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    Default

    What's the best red frequency for beam width. Does it go back down with 650 and 670?

  8. #8
    Join Date
    Sep 2006
    Location
    OH, USA
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    Default

    As general principal, the higher the frequency/lower the wavelength, the easier it is to collimate a thin beam, so I've heard. Makes sense, seeing as Blu-rays use a very very tight beam (which is why they are better than their CD/DVD IR and Red laser counterparts), and every red laser I've seen is pretty wide. As far as I know, 650 and 670 will be even more difficult to thinly collimate than 632nm, but probably wouldn't be too noticeable.

    Someone please call me out if I'm wrong, but I'm pretty sure about this.

  9. #9
    Join Date
    Nov 2005
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    The best beam quality will either come from a single mode diode, or a DPSS laser. Wavelength wont play such a huge part
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  10. #10
    Join Date
    Jan 2006
    Location
    Charleston, SC
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    Default

    Some of the higher power direct-injection diodes have larger beams by their very nature. Dreambeamz has a 500 mw 635 nm diode that puts out a beam nearly 10 mm in diameter! It just barely fits on the mirros for his galvos. In contrast, the DPSS green laser that he has it paired with puts out a beam that is less than 2 mm in diameter. Believe it or not, you really can't notice the difference from the audience's perspective when it's running, but to look at the fat beam in profile on the beam table makes me cringe.

    Some of the high power 650 nm diodes also make fat beams. There's one on E-bay right now that is rated at only 250 mw, and the beam looks to be somewhere between 5mm and 8 mm in diameter. So wavelength alone isn't the issue. It's just that once you get up there in power, it's hard to keep the beam quality up. (Unless you want to spend a lot more money.)

    The modules that Marconi sells (the Maxyz modules) have pretty decent beam specs, but I don't think they can make much over 200 mw each. (If you get two of them, you can use a polarizing beam-splitter cube to get ~ 400 mw) Still, I think they're about the best value right now. Much more power and you start having problems with beam quality and the price goes way up.

    If you want a lot of red (read: more than 500 mw), you have three choices:

    1) Spend a whole shitload of money to buy a top-quality direct injection diode with good beam quality

    2) Spend a reasonable amount of money and live with the poor beam quality of the affordable units

    3) Spend more than #2 but less than #3 and pick up a used Krypton Ion laser - which offers great beam quality - and then deal with the hassle of 3 phase power and water cooling. (Oh yeah, and you'll need an AOM for blanking, which will rob you of 10-15 % of your light output.) And your projector will triple in size and weight!

    Sigh... The joys of technology.

    Adam

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