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Thread: New Laser

  1. #1
    Join Date
    Feb 2011
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    Default New Laser

    I am currently working on a large project to construct a very powerful, pulsed dye laser. This has been the most complex laser I have worked on to date. I designed and constructed it from scratch and although a few of the components were taken from other lasers, these items could have as easily been redirected to an aquarium. Even the trigger circuit was a modification of a series injection transformer which turns out to be a very good choice for its new role. And, even with over 2 dozen O-rings... nothing leaked (knock on wood)!

    Last night I put on the eye ware (a really good idea with this one), checked every conductor, tube and O-ring, and after carefully aligning the optics with a green He Ne, began running up the charging voltage. Just below 1800V, a small crescent of bright orange began to appear within the generalized glow pulsing from the end of the tube; a few adjustments of the cavity mirrors and BAM, I had a laser.

    I will do a video of this project, but I have to finish several systems first. The current cavity is a simple plano-plano and proved the design works, but the cavity I am installing uses an extended telescoping design that corrects for thermal lensing. This should really drop the divergence which is now 9 mrad. The triggered flashlamps use an interesting parallel design to reduce inductance, but suffer as I feared at around 2700V (this lights the landscape) where the lamps treat the flash pulse its self as a trigger and begin to arc. I need to install the Crydom solid state relay to interrupt charging during and slightly after the discharge. Finally, the axicons and the scanner have to be installed in the output beam line. None of this is problematic, should not take too long and is all just loads of fun because..IT WORKED!

    I've included a few pictures.

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  2. #2
    Join Date
    Jun 2009
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    Mesa, AZ
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    Default

    Excellent!!! I've never been as motivated to build a laser as I have been since seeing your video of the Laserecope pumped dye laser you recently posted.

  3. #3
    Join Date
    Jan 2011
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    Boston
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    Default

    Melt some snow with it, Eric!

  4. #4
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    Dec 2007
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    Nottingham, UK
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    Default

    Congratulations.
    This is most excellent.


    Eagerly awaiting further updates.
    - There is no such word as "can't" -
    - 60% of the time it works every time -

  5. #5
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    Jan 2007
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    Florida
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    Default

    Your builds are immaculate Eric. Not a scrap or speck of aluminum or bits of wire anywhere. This could be the clean-room of melles labs. I've never seen anything like it. Looking very forward to beamshot pics. Can you post a pic of the "lighting of the landscape" ? That is an impressive looking rig.

  6. #6
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    Melt some snow with it, Eric!
    Can I add a little pigment to it?

    Eagerly awaiting further updates.
    I never stop learning. Anyone here with some experience with dye lasers knows that they smell. Not that I dislike the smell (jet A near the Lear smells too). Methanol and Ammonyx and Rhodamine are all orderless, but cyclooctatetraene (COT) is the source of that characteristic smell. Unlike the typical closed-fluid dye laser where the smell is very faint unless a dye exchange is being made, this laser smelled strongly and continuously.

    Also, I noticed the threshold on my laser could be as little as 300J with the optics tweaked and the dye mix adjusted optimally, but after only a few minutes and several hindered pulses, the threshold would be above 350J and after several thousand pulses it would be around 450J. This laser has several layers of wavelength selective filters between the cerium doped flash lamps and the dye and the dye is Rhodamine 590 which is a very robust molecule regarding photo degradation. The dye was not depleated

    I was installing a solid state relay in the power line and had my head near the dye tubing and boy did those dye tubes smell and only those tubes. I did some research and learned that silicone rubber tubing is a very bad choice for use with a compound that is an aromatic hydrocarbon and somewhat similar to benzene in structure. I was loosing all my triplet quencher through the tubing and enjoying it in the room air.

    I have ordered polyethylene replacement tubing and I will install it this week.

  7. #7
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    Dec 2007
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    Default

    Quote Originally Posted by planters View Post
    I never stop learning.
    ...replacement tubing
    Frustrating at times, but this is we why we do it!

    I've begun my own dye foray; not at all the same path you have taken, but something which should hopefully yield good results.
    Hence my comment on being interested in your next update.
    - There is no such word as "can't" -
    - 60% of the time it works every time -

  8. #8
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    Feb 2011
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    New Hampshire
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    Dan,
    You saw my re-posted video about the LS pumped dye laser?

    http://www.photonlexicon.com/forums/...28old%29-Video

    If I was trying to produce a really powerful, nearly diffraction limited set of lasers in the red, orange and yellow (even at the same time) then that is how I would go. Using one of the optical decks from the green light lasers, increasing the rep rate at the expense of some of the power and dividing the single, poor quality, 532nm beam into a trio of pump beams, you can get nearly a 50% conversion efficiency in the Rhodamine dyes. It requires some rework of the original cavity to get this efficiency. Alternatively, with a more involved modification of the pumping geometry you can nearly double the maximum output of the dye module to 40W and a single color.

    I am going the giant pulse route because it is simpler and I am not building this laser for display purposes. I want some impact.

    Can you post a pic of the "lighting of the landscape" ?
    That doesn't mean you...can't use it for display purposes! Yes, I will post that once I get it together.

  9. #9
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    Jan 2011
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    Boston
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    Default

    My very first laser that I ever made was a pumped dye laser with a tunable diffraction grating. Be careful smelling those fumes, but as you are an MD, you know the risks of aromatic hydrocarbons. Of course, I just as bad, ingesting carbon fiber and MEK doing composite work.

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