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Thread: An MCA Thread (this is a continuation of a discussion from the Big Green Thread)

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    Default An MCA Thread (this is a continuation of a discussion from the Big Green Thread)

    Hi everyone!
    This thread is a continuation of a discussion from another thread about producing green (532nm) DPSS laser light. This was requested to avoid gumming up the works on said other thread (The Big Green Thread: here) by having too many different discussions about different methods of producing 532 laser light. This thread will primarily pertain to MCAs (monolithic crystal assemblies) which are a nice simple way of getting fairly high power green (500mw to 1 W) from a pre-assembled crystal assy. The crystals are bonded together as an assembly simplifying the construction of a green laser. The only additional components needed other than the MCA itself are an 808nm pump laser diode, a lens for that diode , collimation/ corrective optics, and an IR filter, if I understand this correctly.
    To get started, I'll copy/paste here some of the posts from that thread, and we can hopefully continue the discussion.. Thanks!

    clicky: (twice)

    Click image for larger version. 

Name:	mca posts.jpg 
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    Oops, prolly should have posted this 1st ..

    This is the 1st post :

    __________________________________________________ __________________________________________________ _____________

    This MCA from an ebay auction just came in the mail an hour ago.. Now just need a 4W 808 pump diode, figure out how to sandwich it w/ the indium foil and heatsinks, and get the right lens to pump it in the right direction .. and of course hook up the web cam to "view" the alignment. No looking at this puppy w/ bare eyeballs. Sure is a tiny thing. There's some part numbers on the case. This should be good for about half a watt of 532 ..




    Found this page in a VLOC pdf catalog .. looks similar but the angle of the 2 crystals is different..

    Attachment 35567

    This is side pumped. Does anybody know where to focus the 808 spot on this thing?

    Here's the ebay listing.. looks like he's still got more for sale (if anyone's interested) .. :

    http://www.ebay.com/itm/500mw-532nm-...item19d687bb1a
    Last edited by steve-o; 11-11-2012 at 13:53.

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    Ok, found this heatsink from a cpu cooler. I filed a little bit off the edge and it looks like plated copper. I don't know why they plated it but hoping it'll work w the indium foil inbetween it and the MCA. Thoughts?







    I'm not quite sure of the layout.. something like this, plus I guess another heatsink on top? .. or the vanadate doen't need heatsinking ?


    Last edited by steve-o; 11-11-2012 at 14:11.

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    Set a copper block on that at right angles. You may need very short distances from the MCA to the pump diode lens, and from the pump diode lens to the pump diode.

    Also, you nrrd to end pump this MCA. The area you need to pump is the thin purple stuff.


    Steve
    Attached Thumbnails Attached Thumbnails STEVE-O_MCA.png  

    Last edited by mixedgas; 11-11-2012 at 14:22.

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    OH !! Ok I kinda had it all wrong Thanx again Steve !!

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    Default That was easy !

    Found an old Lasever 80mw greenie that was almost dead, yanked it apart, tested the 808 pump diode, looked to be putting out about 700-800 mw, stuck the MCA in front of the 808 diode and wow. A green dot






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    I did try to get that across , should of picked better words

    Quote Originally Posted by steve-o View Post
    OH !! Ok I kinda had it all wrong Thanx again Steve !!
    When God said “Let there be light” he surely must have meant perfectly coherent light.

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    I suppose that's my fault, when someone said "end pumped" or side pumped or whatever, I didn't think right thru the middle.. more like on an "end" .. oh well.. no probs ..
    onward toward lensing now .. and finding that 808 diode. Steve seems to think 4W pump is too much .. ? I can turn it down .. Would a 808 diode w/ FAC be a good thing? Here's the seller's setup.. kinda crude, I like it. Where does the friggin indium foil go? I'll have to go back to re-read the big green thread again to see if I can figure it out now .
    Cheers and thx y'all
    The seller's image (the bottom one's magnified) :
    Im going to try and attach labels in a bit.. try to figure out what's what .. looks like he's just got it clamped in there w copper plate like Steve was talking about and a U shaped aluminum piece ..





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    Quote Originally Posted by badger1666 View Post
    I did try to get that across , should of picked better words
    Or... a picture is worth a thousand words.. like Steve's pic he posted ..// cleared it all upp-on there



    So Steve, are you saying that the vanadate gets hotter than the KTP and it should be heatsinked more ?
    Last edited by steve-o; 11-12-2012 at 16:17.

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    [Quote:
    So Steve, are you saying that the vanadate gets hotter than the KTP and it should be heatsinked more ?[/QUOTE]

    Yep, indium goes between the copper and the vandate side of the MCA.

    Beam quality looks amazing for a raw, unfocused, 808 diode pumping a MCA, even with no collimating lens.

    KTP likes being reasonably warm.

    Steve

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    Thanks Steve again for the info..
    Yeh the dot is pretty nice for no lenses at all, but of course it's really divergent. Guess we'll see what happens when I get a *proper* pump diode ..
    This 808 pump may even have a fac lens on it .. I didn't see one tho .. but I have no microscope atm ..
    Last edited by steve-o; 11-12-2012 at 17:54.

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