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Thread: Dichro replacement - laser readings

  1. #1
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    Default Dichro replacement - laser readings

    I am starting the replacement of my Edmunds dichros with my dichros from Bridge. I will update this post as I progress so check this first post for updates.

    My optics are all pretty dirty right now but I wanted to measure what I currently have. Here is what is currently exiting my galvo mirrors. The order of my lasers if Green Blue Red. This means green passes through 2 dichros. Blue bounces off one dichro and passes through one dichro. Red bounces off one dichro and does not pass through any other optics.

    All - 140mw
    Red - 100mw
    Green - 18mw
    Blue - 10mw

    The white color balance is actually pretty decent with these power levels which is kind of interesting. The red to green ratio is about right but the blue is about 1/4 that of what is considered to be what you need to get white.

    This is pretty pathetic considering that my lasers are rated at 180mw(R), 50mw(G), and 70mw(B). There are a heck of a lot of losses! Next step is to pop the top and start taking other measurements.

    Now I have removed the galvos so I can measure directly after the dichros. The galvo mirrors kind of suck to say the least.

    All - 237mw
    Red - 171mw
    Green - 30mw
    Blue - 15mw

    Next is to remove the red dichro to see how much power my red directly and see how much power is loss through it from the blue and green.

    Things are getting interesting now! These readings tell me that my red laser only loses about 5mw bouncing off the red dichro. My blue power is really low and I am starting to wonder if it is still putting out the power it should be! There are hardly any green loses through the blue dichro. Max rating is supposed to me 50mw and it is 48mw. Hmmm.

    All = N/A
    Blue+Green = 63mw
    Red = 176mw (this is directly from the laser module)
    Green = 48mw
    Blue = 22mw

    Next I will remove the remain blue dichro so that all laser powers can be read:

    Red - 176mw
    Green - 52mw
    Blue - 20mw

    Based on all if the above here is the data for the Edmunds dichros:
    Blue Dichro
    -----------
    Green pass through: 52mw in, 48mw out = 92.3% efficient.
    Blue reflect: 22mw in, 20mw out: ~100% efficient

    Red Dichro
    ------------
    Green pass through: 48mw in, 30mw out = 62.5% efficient.
    Blue pass through: 20mw in, 15mw out = 5mw or 75% efficient.
    Red reflect: 176mw in, 171mw out = 97% efficient.

    So it seems like the dichros are very good mirrors but pass through is not as good. The blue dichro seems fine to me and within the advertised specs. The red dichro pass through is pathetic, though. I will attempt cleaning it to get better readings.

    Next I installed the Laser wave Red reflect dichro. Here are the results so far:
    Red Dichro
    ------------
    Green pass through: 50mw in, 40mw out = 80% efficient.
    Blue pass through: not mmeasured yet
    Red reflect: 192mw in, 188mw out = 98% efficient.

    So far, the LaserWave is slightly better at reflecting and quite better at pass through. Note, this is at 45 degrees. When I rotated the dichro to around 30 degrees the efficiency went up to 90%. Much better. I may decide to modify my laser positions to be at 30 degrees or at least as far as i can rotate them without bumping into other stuff.


    -----------------------------------------------------
    Side note:
    Well, it appears that my Lasever 50mw laser is dieing. When I bought it I was getting 70mw out of it. Now it only puts out 20mw. I am not too surpised based on other people's reports about these Lasever blue modules. My good old Aixiz green laser is going strong and still rock solid at 52mw. It also has the best beam of them all. It is one of those "big dipper" lasers without a TEC. I am really happy with it. My red is still doing well, too. I made it from an Aixiz 200mw diode but I originally set it to 180mw. So, I have lost 4mw but that could be due to anything. I am very happy with it and may eventually combine two of them.

    I am going to hold off on putting in my new dichros until I get my blue laser sorted out. Needless to say, I am not happy. I need to check if it is under warranty.







    Red


    Keep checking back for updates!
    Last edited by carmangary; 10-05-2008 at 13:54.

  2. #2
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    holey sh####

    Is it possible to lose that kind of power just because your optics are dirty???
    damnn

    Can you difine dirty?
    Is is dusty or really greasy finger dirty?

  3. #3
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    Central Florida
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    Lightbulb

    I'm right there with you man. At SELEM I measured after the scanners and was not pleased. I lost at least half, if not more. I just noticed the other night that my pass red, reflect green is not ppassing 660nm very well at all and swapped it for one of the small T/R, R/G dichros from Bridge. I seem to get better transmission but do not have a meter. The "waste" beam is much dimmer.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  4. #4
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    Default

    They are dirty from just being exposed to the room air and to having some fog blow on them I guess. I am going to attempt to clean and take some more readings. I'll find out exactly where the losses are coming from.

  5. #5
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    DAMN! did you get the new 25mm dichros and mounts from laser wave?

    i just got 10 the other night and they look great! i really like the improvement they made on mounting the dichro!
    -Josh

  6. #6
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    Default

    Well, good news. My blue laser is less than a year old so should be under warranty. I sent an email to Lasever to see what they can do.

  7. #7
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    Quote Originally Posted by thesk8nmidget View Post
    DAMN! did you get the new 25mm dichros and mounts from laser wave?

    i just got 10 the other night and they look great! i really like the improvement they made on mounting the dichro!

    Hey Josh

    Could you post some pictures of the mounts somewhere

    Troy
    RTI Piko RGB 4 Projector
    CT6215 Scanners & CT 671 Amps; CT6210 & Medialas Microamps.
    RGBLaser Systems 6000mW RGB Module - 638nm/445nm/532
    LD2000 Pro + QM2000.net + Beyond
    Etherdream + LSX

    Old Projector Build


  8. #8
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    Default

    Check out my latest measurements in my 1st post.

  9. #9
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    I'll add a point to think about, for power measurements before and after dichro's : the IR part of your laser.

    If your laser emits IR (even a little), it will affect reading on your power meter, but only before passing the dichro, since (for a green pass / red reflect one) it will let the green pass and cut all wavelength higher. So you'll read a lot less power after the dichro than before, but the real visible power drop will effectively be less than that

    I observed that yesterday, when testing my new 300mW 532nm laser. I was wondering why my dichro was eating as much power. It was eating a lot less after reading again with an extra IR filter... Good news, my dichro's are efficient! But bad news, I was really disappointed when I discovered that the real visible power of my new laser was under the spec, although it was supposed to be much higher !!!

    So a good measurement protocol would mean using a good quality IR filter, in addition with the one into the laser.

  10. #10
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    Default

    what brand laser would that be?

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