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Thread: 100W RGB Laser Light Engine

  1. #1
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    Default 100W RGB Laser Light Engine

    Starting a new thread with a more compelling title

    I've got a Laser Light Engines cabinet that is supposed to be >100W RGB solid state lasers intended to replace the arc lamp used in a movie projector. One discussion I found says that it's capable of making 28,000 lumens which is much brighter than a 2KW arc lamp! It's a half height cabinet full of stuff, including a chiller. I'm going to start digging into it today and see if I can light it up without setting the place on fire. Sadly, LLE went out of business a few years ago (~2014) and there's not much info available for these. Their old web site is partially saved in archive.org, but the PDF spec sheets did not get archived.

    https://web.archive.org/web/20140705...htengines.com/
    https://web.archive.org/web/20130929...gb-engines.php

    I'm pretty sure I can reverse engineer it enough to get it going, but if anyone has a contact that used to work at LLE or possibly saved any of their spec sheets, please let me know.
    Attached Thumbnails Attached Thumbnails IMG_9214.JPG  


  2. #2
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    Lots of interesting info in their patents. Mostly related to the techniques they use to despeckle the lasers though.

    https://www.google.com/search?tbo=p&...gines,+Inc.%22

  3. #3
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    Very interesting. Does it make green in a similar fashion to the consumer projectors we've seen? I see red and blue wavelengths listed, but no green.

  4. #4
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    The tan colored chassis just above the chiller is the green laser. From what I've seen on the inside, it's a simple diode pumped Q-switched L-fold, but there is a spool of fiber inside that might (based on reading the patents) be a Raman shifter to generate red from some of the green. There's a motorized 1/2 waveplate and PBS to change the ratio of the 2 outputs. I'm guessing this is how they control the white balance.

  5. #5
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    Turn the green off and you got one serious plant light!

  6. #6
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    This looks brilliant; can't wait to see more as it develops.

    They auctioned most of their smaller bits on eBay about 18 months ago from their dev lab when it was bought out. Most was green fibre lasers and arrays of blue diodes. Most had very poor beam profiles for "traditional" laser projectors. Great pump sources though.

    For their 3D stuff, they were looking at putting 2x R, 2x G, 2x Blue in about 20nm apart; one for the left eye, one for the right.
    e.g. 620nm / 640nm // 515nm / 535nm // 445nm / 455nm etc.
    - There is no such word as "can't" -
    - 60% of the time it works every time -

  7. #7
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    Neat project! Would be interested to see some pictures with the lids off
    If I am interpreting their patents right their proposed scheme was to use a q-switch green laser coupled to a raman converter to generate red and broaden the linewidth of the green for despeckle. Then by adjusting the waveform to q-switch (short pulse or long) they could control the spectrum at the output of the raman converter (short pulse - red, long pulse - green with broadened spectrum). Then use blue diodes for the blue channel.

    They also had talked about using OPOs but I think everyone gave up on that due to the absurd complexity...

  8. #8
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    Here's a picture of the guts of the green laser enclosure. Completely different than the self-contained DSG-265 (depeckled green) module I've seen a few pictures of. I'm guessing this is an early prototype since it's made with mostly Newport and Thorlabs parts. There are 2 CS bar diodes side pumping (something, presumably Nd:YAG) and an L-fold doubler. Everything is water cooled, but there doesn't appear to be active temperature control of the pump diodes or SHG. The output is split into 2 fibers. Best I can tell, one goes directly to the back panel and the other goes through that 70m spool of fiber before hitting the other back panel SMA connector.

    Hopefully I'll have time to really dive in this weekend or early next week.
    Attached Thumbnails Attached Thumbnails 023.jpg  


  9. #9
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    Looking forward to seeing more of this. I have to admit, after reading up on Raman shifted lasers, I don't understand any of it! Very cool though! I think Eric (planters) was working on a Raman shifted vanadate laser but I haven't seen any more about it so I am really hoping you get some photons out of this!
    Last edited by absolom7691; 12-13-2017 at 14:22.

  10. #10
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    Very interesting, not at all what I expected it to look like inside.
    The gain module looks like a 'multipass slab' module from Q-peak http://www.qpeak.com/sites/psicorp.c...ser/Corona.pdf
    It is possible that they did the whole laser design, I doubt it though because their lasers usually look a lot more 'finished' than this one.

    If you are not able to get the controller to turn on it looks like running the system manually will be pretty easy, hit the start button on the chiller, and the output enable on the two diode drivers and it should be good to go! By the looks of it the only components directly controlled by the controller are the q-switch and waveplate rotator.

    They do have a lot of patents related to splitting the output power from the system into 2 fibers to allow them to optimize the conversion efficiency to red. In your system, with one long and one very short fiber, I am fairly sure that the long fiber is the raman converter which generates the red light, and the short fiber is used to 'despeckle' the green by shifting its wavelength slightly toward yellow to broaden its bandwidth. The waveplate is just to adjust the red/green mix to get to he color temperature correct.

    One piece of advice - be extremely careful with those fibers. In order to get high enough intensity in a silica fiber to shift green light to red light in a 100m length of fiber the intensity on the facet is enormous. The fibers probably have end caps on them, but it will only take one misplaced speck of dust to cook the fiber face. Similarly, if the fiber coupler is mis-aligned and the focused beam hits the metal surrounding the fiber it will vaporize the surface and contaminate the fiber. With multimode fiber that is not as big as a concern, but still something to watch out for when dealing with a system that was recently moved.

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