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Thread: A New Laser Project.

  1. #1
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    Default A New Laser Project.

    As everyone probably knows, I am very interested in dye lasers. Take a quick glance at the linked article.

    I am going to try this with a few twists. Firstly, I will use a small, completely enclosed, thin layer of fluid circulated by a peristaltic pump. Secondly, I will use one of the yellow or orange water soluble dyes, And finally, I want to drive this with a couple of 520nm diodes focused and convergent on as tiny a spot, within the dye, as possible.

    Creating a compact, directly modulated, portable, DC powered source of single mode yellow to orange laser output might interest others as well.

    My question is, what is the native divergence and practical power (before the beam specs deteriorate) of the best green diode available?

    http://www.dtic.mil/dtic/tr/fulltext/u2/a275114.pdf



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    ... for me more interesting is the high absorption peak of Rhodamine700 at 652nm - I have a diode module with 20 Watts @652nm out of a FSMA fiber head what can be refocussed to a spot of 0.4mm diameter.

    Any idea, what would be the efficiency and max. possible power with such a setup?

    Viktor

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    For these dye lasers, the absorption peak is not very demanding. The large range of concentrations that can be utilized with efficient florescence permits you to pump them with sources well away from the peak. The more important control is the achievable fluence. with a spot size 10x as great as in the article and a power roughly 100x as high you will probably see a slope efficiency nearly as high as when they utilized the CW dye source to pump their laser. The one potential caveat is that the faster the dye moves past the illuminated region to reduce the interfering,triplet absorption the better and here you will have a 10x the exposure interval. The cell I am designing will unlikely be able to match, let alone exceed the flow velocity of a dye jet. This might pose a problem.

    The reason I am proposing the green pumped system is the potential to produce laser output in a region where no practical (affordable) compact sources exist.

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    ... what do you think - is pumping with the red 20W-CW-diode @652nm more interesting or effective than flashing with a pulsing N2-TAE-laser @337nm?

    Viktor

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    Planters, in the paper I sent you, they estimated an 11 micron Pump Spot size.. If you can hit that, I think its doable. Dye lasers have been pumped with a few 10s of mW of HeNe, lasing in the near IR. The record is a threshold with something like 5 mW of red HENE pump, with a very high gain IR dye... Hene's advantage, as well as Argon, was the small spot size with a pure TEM00 beam. Plus we have much better coatings now then in the 80s...
    !
    Our friend at Joss Research thresholded a 599 Ring Dye at ~ 2 watts of DPSS 532 Green multimode pump a while back. I had sent him the optics that were missing from the dye laser head... If he had pump power way above threshold, he might have got it aligned better, been able to toy with the mixture, and brought that threshold way down, while increasing lasing output... He did that with a less then optimal water based dye.
    !
    Since you have that six Watt tight green, I'd start there, get the cavity lasing, and work your way through the compressing optics for the diode later.. I'll see what I have in the dye optics pile, Lord knows I'll never use them at this rate.
    !
    Steve
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

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    Since you have that six Watt tight green, I'd start there, get the cavity lasing, and work your way through the compressing optics for the diode later.. I'll see what I have in the dye optics pile, Lord knows I'll never use them at this rate.
    Thanks, I may call you on that offer as this will probably require a few trial set ups to get that hemispherical cavity optimized.

    I do not doubt that I could get this to work with an excellent green source and I have that.

    The real test is to utilize the elegance of the focal location to allow very highly convergent pump light. This will mitigate the beam quality issue of green diodes.

    The other nicety is the simplicity of adjusting the focal spot of the resonator by only adjusting the X/Y of the concave partial reflector.

    Not to mention the ability to match the mode diameter to the pump diameter.

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    If you can make it they (I) will come. I have been trying for a good quality tight red for ages.

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    I know. I to have grown weary of correcting, filtering, enlarging... to compensate for the low quality of direct diode beams. Single modes are also limited in power. The neat peristaltic pumps that I have been playing with for my big dye projects are really nice.

    http://www.simplypumps.com/pumps/cat...ristaltic.aspx

    These leak free, high flow, high pressure pumps mean that a small self contained loop with various dyes could easily be placed within a typical projector footprint. Both the xanthene and the pyrromethene dyes which are the best candidates work in pure water and even better in water/methanol or water/isopropyl solvents. These are messy to mix, quite low in toxicity. The advent of the green diode with watts of power and direct modulation means that the old, ion laser or bulky DPSS green pumps, previously used for the typical dye jet, is a significant simplification.

    The dye head that I show in one of my old videos about the "yellow laser" is similar to the design of the head in this new project; in form, but not in scale.

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    Posting to track, and.. Ya - a Couple hundred mW of analog-modulatable Yellow and/or Orange in a < Microwave-size form factor, and for < $22K (ie: Fiber Lasers..) ...I'm all eyes.. Especially for Lumia / Diffraction-dependent-fx.. Native Yellow adds such a magik-dimension / is such a great 'Cure for the Common RGB-Lumia'.. Cyan, too.. Sign me up!

    j
    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

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    Sign me up!
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