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Thread: Is this setup ideal? I'm losing some laser light!!

  1. #1
    Join Date
    Apr 2011
    Location
    Houston, Texas
    Posts
    37

    Default Is this setup ideal? I'm losing some laser light!!

    While tuning my scanners I noticed that when my front panel was off that some of my Laser light is actually going through the deflectors of whatever they are called.

    Sorry I don’t know all the proper names yet, still rather new to this.

    Is this setup ideal?

    I’ve seen pictures of other builds that uses mirrors to reflect the laser to the scanners.

    It seems logical to me that if some of my laser light is passing through these lens then I’m not getting the full potential of my beams.

    Am I correct is thinking this way, or is this common in Laser Projector builds?

    I’ve enclosed 2 sets of pictures.

    The first shows the red and yellow dots leaking through while the front panel is off.

    The second set shows pictures of my actual projector setup.

    I’m hoping some of you Laser Projectors gurus can give me some insight on this.


    Pictures of the dots I noticed leaking through:

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    Inside the case:

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    Any help or information would be greatly appreciated.

    Thanks in advance,
    Mike

  2. #2
    Join Date
    Jul 2006
    Location
    Connecticut, USA
    Posts
    2,478

    Default

    Hi Mike-

    Those "deflectors" are called dichroic filters. They are used to mix your laser colors (as im sure you have seen) It is perfectly normal for these to "bleed" light. There are no sorts of optics that are 100% efficient, therefore, there is going to be bleeding of light through any optical surface and there will be back reflectance off of an optical surface.

    That being said, there are better optics than others. The bleed through of your red and yellow dot dont actually look too bad. it is very deceiving to judge bleeding light or reflected laser light by its "dot." By the looks of your projector and optics, i am guessing that this is some sort of a chinese import? (or close to). And those are notorious for pretty poor optics. Average reflectance of the dichros are usually around 85% (meaning 15% loss) and probably about 80-85% transmittance. those numbers start to add up DRASTICALLY.

    Each optical surface has losses for reflectance and transmittance. These optics look like they are on the lower end. (im not saying that to put your system down. just stating an observation). dichros that are very efficient are pretty expensive. I have dichros that reflect (at their designated wavelength) around 98% and transmit about 92-94%. Thats about as good as you can get it. But they are also about $100.

    All that being said, your light losses are completely normal. Probably a little on the higher side (although it doesnt look like that from your pic. but as i said, you cant judge that by a picture). but normal.

    -Marc
    http://www.laserist.org/images/ildalogos/ILDA-logo_colored-beams_Corporate_150w.jpg

    ILDA- U.S. Laser Regulatory Committee

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  3. #3
    Join Date
    Apr 2006
    Location
    Miami, FL
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    3,589

    Default

    having some reflected off of the dicros is normal...

    it looks like the have blue then green then red furthest from the scanners...

    this is less than ideal since red is going to be your weakest color... it should be red closest to the scanners followed by green then blue or red, blue, green, depending on the power level of your green

    the whole "blue should be closest to the scanners" practice was more of a 473nm thing, when blue was by far the most expensive color per mW

  4. #4
    Join Date
    Feb 2010
    Location
    Melbourne, Australia
    Posts
    1,106

    Default

    ^^ What they said.

    Here's a photo from my cheap and cheerful projector, when I was building it, showing the leakage. These are Edmund Optics dichroic filters.

    Click image for larger version. 

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  5. #5
    Join Date
    Oct 2006
    Location
    Central Florida
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    7,067

    Lightbulb

    Perfectly normal if not desired. If you can get access to a meter you can measure the "loss". Even my Kvant does it; I doubt you are losing much. If you look at some of the DIY rigs you will see odd angles; in my DIY rig I try to find the most efficient angle for each dichro to minimize the losses, although I don't think you have that option, but neither do I in my Kvant.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  6. #6
    Join Date
    Apr 2011
    Location
    Houston, Texas
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    37

    Default

    Thanks for the replies guys.

    @ Marc: Yes this is a budget based import Laser Projector from China, I decided to get something cheaper to get my feet wet so to speak in this new field before dropping 10K or more on a really high end system. I have tons to learn still on the Laser and with QuickShow as well. I figured at least this way I have something I can use for parts also if I decide to make my own projector later. This one is far from perfect but scans nice images for the amount of money I spent. I might consider getting some better "dichroic filters" as you mention those probably being low end. Thanks for clearing the name up on that by the way.

    @ Flecom: Yes you are right, they do have it set up Blue closest then Green and finally Red farthest from the scanner. I never really thought about the Red being the weakest color and the furthest away from the scanners until you mentioned that. I might look into seeing if it would be hard to swap the position of the Blue and the Red.


    Once again thanks for all the input, I didn't know if that was a normal thing or not.

    Now I do!

    Thanks,
    Mike

  7. #7
    Join Date
    Apr 2006
    Location
    Miami, FL
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    3,589

    Default

    ya its normal, and some friendly advice, don't do any public shows with this thing in texas, they will fuck your life and take your projector...

    now thats assuming you don't make it complaint, do a product report, get a variance, and do whatever you need to do with the state of texas to make it all legal

    it might not be too difficult to make that thing complaint, and it might be worth your time it actually looks amazingly well built for a chinese projector

  8. #8
    Join Date
    Apr 2011
    Location
    Houston, Texas
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    Default

    I don't plan on doing any public show with this projector, I'm just doing stuff with it in my home and when we have private parties.

    I'd have to do a few modifications to make it "legal" it needs an emergency stop for one thing.

    It does have a key switch (very cheap one) that does work like it's supposed to.

    Overall it has some minor things that need to be fixed but I'm actually happy with it for what I wanted as a "Learning Projector".

  9. #9
    Join Date
    Apr 2006
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    Miami, FL
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    Default

    ya its going to need a class IV reset and some other fun stuff, should be doable...

    if you dont mind me asking where did you buy it and what did it set you back?

  10. #10
    Join Date
    Apr 2011
    Location
    Houston, Texas
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    Default

    Quote Originally Posted by flecom View Post
    ya its going to need a class IV reset and some other fun stuff, should be doable...

    if you dont mind me asking where did you buy it and what did it set you back?

    It a LaserKing Projector (RGB) with the following specs:

    300mW 640nm Analog 10k
    200mW 532nm Analog 10k
    800mW 447nm Analog 10k
    40kpps scanners


    It ended up costing me $1700 because I wanted the 640nm Red instead of the 635nm they offered with it. If 635nm doesn't bother you then you can get it for around $1400 +/- a little with shipping.

    I plan on writing a review on it once I've played around with it a little more and some video also.

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