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Thread: Any tips for knife-edging dual 445's...?

  1. #21
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    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
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    not sure what lens you used. sharply focused at 40' and through a prism pair, i get a very thin line maybe 12mmX3mm. if you're getting at 14mm square, it sounds you might be having a focus problem.

    Quote Originally Posted by CDBEAM View Post
    Well...I am confused ( A normal state )...at 40' ( slightly over 12M )....a single 445 LD , with O-Like collimator, going thru a set of P1t8ull's prisms produces a ( VERY close to ) 14mm square. I have done this set up. By taking another 445 LD and passing thru a waveplate....one square is overlaid via the PBS on top of the other.

    Even if the square is slightly a rectangle...a very slight rectangle....then you would be comparing a fat plus shape that at 40' that looks like a circle.....to an almost square rectangle. I guess it them comes down to energy density/square mm vs. the geometry that most closely approaches a circle. I would speculate ( read quess ) that the Zuul would have just a bit more energy density....BUT the SD would look just more slightly like a circle. " Pay ya money...Takes ya pick " !!

    I dunno...just speculation ??? Likely at 40 feet...nobody could tell the difference.....and only the photonic obsessed would give a Rat's Ass.

    CDBEAM
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  2. #22
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    Yikes squared !!! SD...you said you are using...."aixiz blue lenses and prisms/cube from the group buy p1t8ull did last year".
    OK...3mm at 40 feet ???????. 12mm x 3mm ??? where is the FA magnification from the prisms ??? Anyone else who really understands optics....please jump in here....for I am clearly confused....and perhaps out of focus too !!

    CDBEAM

    Another question...I assume your beam pic is the geometry at 40 feet ????????? I do not understand !!! That beam geometry....while a great looking circle....is approx 40mm in diameter....when compared to the wall plug plate just to the right of the spot...and is at the same termination plane distance. ??? What am I missing here ???

    Yikes again....I am looking at your front prism.....on the normally placed set.....an it does not look like the normal " Zoof Templete "...??? Just trying to understand optics....my most challenging area !!!
    Last edited by CDBEAM; 09-21-2011 at 19:07. Reason: Added last question
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  3. #23
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    Quote Originally Posted by swamidog View Post
    your design will give you either a "_" or "=" shaped spot depending on the height relation of your diodes. mine gives a "+" that fuzzes into a round looking spot. the spot photo i posted is at 40'. that's the longest run available in my house.

    Hey Swami... whats the measurement of the beam spot here at 40feet? 3x3mm aperature right? what like 15x15 this wall dot? 14x3 would bewithout your prisms or did I misunderstand? Yes I'm confused on the explanation as soo many #'s flew around here.~jimmy
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  4. #24
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    Where did you purchase your PBS? I am not familiar with JML
    Thank YOU

  5. #25
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    CToyz...JML is in Rochester NY. They are very pleasant to deal with. See: www.jml@jmloptical.com

    under beam splitter, part # CPO21361 @ $ 105.00 Not cheap....but 98% transmission and 95% reflectance. Perhaps there is better

    out there....at several times the cost ??? Dunno. Perfect for 445nm beam combining and it looks coated.

    CDBEAM
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    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
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    .
    Beam Axiom #5 ~"Abstract Photonic Expressionism"....is "Abstractonimical" !!
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    Beam Axiom #6 ~ "A Posse ad Essea" ~ From being possible to being actual ...is the beam target !

  6. #26
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    I am looking at mounting the prism pair and see two methods in this thread. I want to avoid over-engineering while building a good, stable and easy to dial in mount. I could any advice on the merits and tricks.

  7. #27
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    Here is my setup. Wave Plate and PBX before the Prism Pair. The trick is setting the Prism Pair at a pretty extreme angle which is well past Brewsters Angle, which results in high losses but a well corrected beam. There is so much bloody power who cares about the losses... I'm getting 1.4 Watts at 1 amp. The beam is 8mm at 30 feet.

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  8. #28
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    Default One way to clamp Anamorphic Prisms

    Mr.P....If you are asking on how to mount a pair of A-Prisms...

    This is how I have done it...the anamorphic prisms are positioned and mounted/clamped with two (2) acrylic plates which are joined with four 6-32 allen head bolts. A 2mm rubber grommet is placed atop each prism to cushion the prism from unequal downward pressure ( Small black circle ). Basically...one is making a sandwhich !!! When the top plate bolts are tightened...the grommet compresses and clamps the prism into position. Thus...adjustments are always doable down the line. There are four (4) additional mount holes in each plate which provide for securing the entire module to your optical platform.

    As to what angle to position the first prism....Brewster ( About 57 Degree ) or more severe as mentioned by LK....well....we are " Between the Devil and the Deep Blue Sea " in this selection !!! At the Brewster angle....minimum transmission loss....BUT...Not maximum beam correction....a more severe incidence angle....more beam correction...but more transmission loss.

    Actually....now that I have been experimenting with the Drlava Cylinderical lens set up...with the ultra low transmission loss ( about 3%) with red LD's...I am going to experiment with the
    C-Lenses and the 445LD... Perhaps that will also be a better way to go than prisms. I hate " waste " beams generated by the prism set up....well....they are a waste !!!!

    Likely others have already done experiments....but I have not seen any posts on this topic. Seems as though everyone ( including me ) have settled on prisms as the #1 method for 445LD beam correction. Perhaps the Good Doctor was WAY ahead of the curve.... Anyone else have improved results with C-Lenses on the 445 ??? Sorry if I did a small thread jack !!!

    BEAM
    Attached Thumbnails Attached Thumbnails Zod Quad Anamorphic Prism Pair v 1.7.JPG  

    Anamprphic Prism Module Pic 2.jpg  

    Anamorphic Prism Module Pic 1.jpg  

    Last edited by CDBEAM; 10-24-2011 at 20:59.
    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
    .
    Beam Axiom #2 ~Yes...As a matter of fact...I DO wear tinfoil on my head !!
    .
    Beam Axiom #3 ~Whe'n dout...Po ah Donk awn et !!
    .
    Beam Axiom #4 ~A Chicken in every Pot, and a Laser Lumia in every Livingroom !!
    .
    Beam Axiom #5 ~"Abstract Photonic Expressionism"....is "Abstractonimical" !!
    .
    Beam Axiom #6 ~ "A Posse ad Essea" ~ From being possible to being actual ...is the beam target !

  9. #29
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    CDBEAM,
    Thanks for the advise and this how I will go. Incidentally, did you machine the hard spacing between the plates for zero clearance and then with the pads just back off slightly on the retaining screws? I am expanding six 445 diodes at once and will be limited by the prism's clear aperture to slightly less than a 2:1 expansion. That's OK as that in turn is the max my scanner will handle. The problem with the cylinders is that only one of the diode beams can be on axis at a time and the others that are off axis will suffer from progressively greater and greater coma the farther they are off axis. So, to minimize this you can correct two independently and then PBS, but then beyond this you will have to correct and then knife edge or have to accept this aberration. This can get pricy.

  10. #30
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    Laserkits,
    I am assuming that you glued the pair down and this is tempting (so simple), but how time consuming was the alignment process. Was this easy; as in align the diodes to the smallest far field spot then insert the prisms and move one or both/back and forth a little? Any special order as you dial it in?

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