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Thread: DTR RGB Bundle/FlexMod P3 Build Progresses

  1. #1
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    Default DTR RGB Bundle/FlexMod P3 Build Progresses

    Here are some photos of my RGB LD build, or should I say the first generation build progress.

    This photo shows the first incarnation using the beam suppression P3 versions. The small breadboard on the right in the 7812 voltage regulator that powers the P3's.
    I later made some minor changes by adding two-pin power connectors for each P3 to the regulator board and their LD connections.
    Click image for larger version. 

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    This photo shows the minor changes and the replacement P3 standard version drivers
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    This photo shows the LDs mounted and running. The 3/8" aluminum plate is part of a recycled mount for a GS120PD XY scanner pair. The empty hole on the left was .50" dia. hole for the Y-galvo.
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    This photo shows that although the three LD copper barrels are mounted equidistant from each other, the blue beam exits slightly off-axis. Rotating the blue LD barrel allows the beam position to fall on the same plane as R&G but is angled away from them. Anyone know if this is because the diode in pressed into the copper barrel at an angle? or do LD's sometime exit off-axis?
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  2. #2
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    Could be the lens. Try rotating that and if the beam rotates with it there is your answer. Don't know how to correct it but as long as the beam strikes the dichro mirror at the same point as the reference beam (Green I'm guessing), then it doesn't matter as you will use the mirror to straighten it up.
    Last edited by WolfMax; 01-20-2015 at 23:55.
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  3. #3
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    It could be the way the diode is sitting in the housing for sure. Did you try taking the diode out and re-seating it?

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    Anyone know if this is because the diode in pressed into the copper barrel at an angle? or do LD's sometime exit off-axis?
    I have seen some diodes that seem to emit off-axis. Only by a degree or so usually.

    Does the beam stay in the same spot when the lens is turned? Sometimes the lens is not concentric with the holder.

    Most likely it is pressed in at a small angle. With the SM diodes it doesn't seem to hurt the beam quality too much.

  5. #5
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    The blues I have are slightly off axis. I press mine in with a lathed tool and a press, so I know the package can is seated. The dies are all off a degree or so. This is aggravated by the prism effect of hitting the lens just off center.

    You can try re=seating it with a tool without removing it if its pressed in. I would not try to "pull" a pressed in diode.

    Steve
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  6. #6
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    Wolfman: Could be the lens.
    Good thing to check-out! Doesn't appear to be lens realted.

    logsquared: Does the beam stay in the same spot when the lens is turned?
    Yes, the beam stays in the same spot during focusing.

    Quote Originally Posted by mixedgas View Post
    The blues I have are slightly off axis. I press mine in with a lathed tool and a press, so I know the package can is seated. The dies are all off a degree or so. This is aggravated by the prism effect of hitting the lens just off center.

    You can try re=seating it with a tool without removing it if its pressed in. I would not try to "pull" a pressed in diode.

    Steve
    Thanks everyone. That's my first thought after seeing that focusing doesn't cause beam shift, that either the LD package isn't seated fully or a die misalignment. I get the impressions from inspection of DTR's copper barrel that the end has to be unscrewed before a slim punch tool can be used to check the seating. Am I correct in that the LD is pressed in from the rear? I'd appreciate someone with experience telling me about how best to go about this. I have "pressing" capabilities (no pun intended) and can make my own tool if I don't have something already.

    Anyone have pictures of a DTR barrel taken apart?
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    i use press my self with a hollow tube, you try to see if it is flat but i would not try to remove the diode once it is pressed in, unless some one has a better method i have always had the diode suffer some damage from trying to remove it once pressed in, either the window on the diode shatters or the top gets caved in when trying to push it back out, if the housing is cheap you can cut along the side but i would not recommend it
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

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    Diode packages have a stepped down can over the diode and a flange. DTRs mount guides the package can in. Then as the flange enters, it engages the sides of the hole which is a few thousandths of an inch of an inch undersize for a press fit. The brass deforms and that's it. Once its in, its in.

    It is a Class I or Class II interference fit. Not quite a weld, but the forces required to remove a interference fit will deform a diode's steel can.

    There are threaded diode mounts available that allow diode removal, ie Meridith Instruments has a product, so does Thorlabs. There are others.
    However the common mount is press fit to be a least cost unit. Its made on a "Swiss Screw Machine". A long rod of brass goes in one end, and mounts come out the other, about every ten seconds or less.

    Its worth some time to watch some screw machine videos on Youtube. Fascinating machines that really opened up the mass production society.

    I had the honor of being the one that arranged a batch of threaded mounts to be made. They are deceptive in the tolerances involved. The rear end has to be pretty darn good, within a thousandth or so,

    Steve
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  9. #9
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    Flmaninpyro has a great tool for extracting the 3.8mm diodes. It goes around the can on the gap between the diode can and the though hole of the module to push on the base of the diode evenly to remove it. Used it many times and never warped the diode in any way. On the diode it is possible with these smaller diodes if off even by the slightest amount the beam can be off a tiny bit but usually rotating it to even the vertical alignment works great and the rest is done with mirrors/dicros.


    http://laserpointerforums.com/f39/di...ml#post1151767


  10. #10
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    [QUOTE=mixedgas;307755
    Its worth some time to watch some screw machine videos on Youtube. Fascinating machines that really opened up the mass production society.

    Steve[/QUOTE]

    Great suggestion, Steve. The https://www.youtube.com/watch?v=eBloIuU4l0I video was one of the most impressive since they mostly used dry cuts and you could clearly see the machining.
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