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Thread: 405nm fun and usage

  1. #1
    Join Date
    Oct 2011
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    Default 405nm fun and usage

    So we talked about a few things about 405nm on A1XDs help thread and didn't want to derail it any further and haven't seen a thread for it so I made this one.

    To continue the discussion:

    Quote Originally Posted by dkumpula View Post
    Well that's a great idea! My understanding is that these walls are generally painted with strontium aluminate and erased with lots of deep red (~700nm). A big wall of strontium aluminate is pricey. A section of a back wall that I did with small particle strontium aluminate measuring 4 feet by 8 feet cost me more than US$250 in paint to get nice even coverage.



    I didn't see the diodes that you referred to. I've been using DTR's 16x 405nm diodes which are single mode or very close to it. Those can be run at 750mW each (more over a short duration) which is more than adequate for drawing on GITD paint. Too much power in fact leads to poor drawings as the 'flare' from the beam charges the areas around what you are drawing. I have blown several of these diodes however. I know they are ESD sensitive, but it doesn't appear to be my problem. Either back reflection or just long drawing times at high powers are my current (pun intended ) suspects.

    -David
    I don't think the wall is painted as the layers of what appeared to be wallpaper were coming undone on the corners but it glowed for quite some time.
    Next time I go there I'll ask the staff about it. I also have to give the planetarium girl a better pointer as her little 1mw red pointer was barely visible ha.

    I read that people have been popping those diodes even at low currents but I didn't know they were popping that low! Did you run yours as low as 450mah and they burned out still??

  2. #2
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    I'm going to tag along on this post as well. I've been playing with an S06J 12x diode and Zinc Sulfide paint. I see I'm not the only one to experience the "flare" that leads to a more foggy image as opposed to a nice sharp image. I'm going to try some different lenses as I'm only using a generic acrylic lens right now. I've got a G-2 lens in the mail but I think a three element lens might be the best solution for this purpose. My scanner mirrors are also on my list of improvements needed but I'm still exploring this.

    I haven't played with strontium aluminate yet either. For my purposes I like the shorter glow time of Zinc Sulfide, plus it's much cheaper. Lasers with glow int he dark paints are fun though
    LASERS!!

    1x Homemade 500mW 405nm Projector
    1x Homemade 1.2W RGB Projector
    1x Lightspace Color Ray Series 6W RGB
    2x Lightspace Venus 2W RGB

    ZPL Lighting www.zpllighting.com

  3. #3
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    Syracuse, NY
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    My G-2 lens came today and I am very impressed with the improvement. The image is much sharper than it was before. This S06J is running about 650mW @500mA with the G-2. The substrate is zinc sulfide paint from home depot.

    Last edited by ZeroPoint; 02-14-2017 at 21:37.

  4. #4
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    Oct 2011
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    Oh gawd I gotta build a projector. I see what you mean by the effects of the zinc sulfide. They make a really good effect in addition to the patterns produced by the actual projector. Oh yes I learned long ago that glass optics are far superior compared to acrylic. At lower powers it's not so noticeable but the higher you go up and the more complex the patterns you notice more and more.
    Zeropoint thanks for sharing this. So have you had any problems with 12x diodes burning out too quickly? The 16x diodes seem to burn out even at low mahs but if the 12x diodes are more robust then I'd rather get a few of those instead. I'll do some searches later.
    Also you aren't that far from me. I'm in schenectady ny. We should ride down to the SELEM this year if I get my car on the road.

  5. #5
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    I've popped a couple diodes but they were all user error. I accidentally put 24 volts to one when I wired a DIY driver wrong and another I adjusted wrong and put 650mA to. My current diode I've only had about a two weeks but I've run it for multiple hours at a time at 500mA and it has been fine. I'm definitely loving the lens. It's actually a knock-off G2 by Aixiz but it was only $8. I'm not sure how it compares to a real G2 but I'd say it was worth the money. I'll be getting more for sure.

    I would love to make it to SELEM sometime. It all depends on my finances though. I'm going down to NYC March 2 to take the exam for my NYS certificate of competence and then I need to start saving for a friends wedding in Mexico (the country, not Mexico, NY lol). SELEM might be a real possibility though. There's another PL member in Albany who might be interested in the trip too. My brother lives in Albany as well so next time I'm out that way maybe we can get a few of us together and play with some lasers.
    LASERS!!

    1x Homemade 500mW 405nm Projector
    1x Homemade 1.2W RGB Projector
    1x Lightspace Color Ray Series 6W RGB
    2x Lightspace Venus 2W RGB

    ZPL Lighting www.zpllighting.com

  6. #6
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    ... with my experience this "fast dying" of diodes is mostly caused by current spikes and transients and by "driving them at specs" ... I'm driving the diodes with less than 90% spec'd current.

    For this I'm building my own diode-drivers with current regulation for pulsing with up to 35 Amps and with up to 1MHz timing resolution - I've posted some infos for the last driver here:
    http://photonlexicon.com/forums/show...Recommendation

    Until now all my "RIP" diodes were user errors too or while driver developing or "testing absolute limits" ...

    Viktor
    Last edited by VDX; 02-16-2017 at 01:25.

  7. #7
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    Quote Originally Posted by ZeroPoint View Post
    My G-2 lens came today and I am very impressed with the improvement. The image is much sharper than it was before. This S06J is running about 650mW @500mA with the G-2. The substrate is zinc sulfide paint from home depot.
    That video you posted looked great. Zinc sulfide is definitely the right paint for this type of pattern. It would likely look like a bright mess if it were strontium aluminate.

    Regarding the colimation lenses, I've been using DTR's G-2s almost exclusively with the 16x diodes, but if I were using bullet mounts instead of Lasershowparts brass mounts, I'd probably be using Aixiz G-2s to save some money as the correction and power specs for most diodes are almost identical. (Note: The threads on the Aixiz G-2s are too large for Lasershowparts diode mounts and will jam before you can get them colimated correctly.)

    As others have found, a tight beam is preferred for accurate drawing on GITD materials as well as not too much power. In general, you can't go wrong with the G-2s (either kind) for most diodes, but low power reds correct better with acrylic lenses in my experience (assuming you are willing to deal with the ~30% loss in power.)

    Regarding premature deaths of my 16x 405nm diodes, as I was saying earlier, I believe the most likely culprit is back reflection off my PBS cubes (all of my 405nm builds have two 405nm diodes PBS'd together). I've started aiming my diodes at a slight angle so the back reflection isn't bounced back into the diode, so we'll see if this helps.

    Keep having fun with your GITD experimenting / artwork!

    -David
    "Help, help, I'm being repressed!"

  8. #8
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    Holy Moly! ZeroPoint that video is AWESOME!

    -Sal

  9. #9
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    What brand of zinc sulfide paint are you using?
    I'm mostly finding powders online.

    ...Mike
    Runs with Lasers

  10. #10
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    Thanks guys!

    The Home Depot sells Rust-Oleum brand glow in the dark paint. They sell both a spray can and a small 7oz can of latex based paint. I used the latex paint. I tried the spray can but it would require far too much paint to get a thick enough coat for good results. The latex based can was perfect for a few thick coats on the 2'x4' ply wood panel in the video, with a little bit left over. It doesn't actually specify zinc sulfide on the can but based on the color of the glow and how quickly it fades it's almost certainly zinc sulfide. The 7oz can runs about $10. Just make sure you stir it real well before using it. You'll notice that the powder all settles to the bottom of the can pretty quickly. It took me about 5 minutes to get it mixed well after opening it for the first time. I need to redo my panel though. I bought a spray can of white primer to cover the panel before putting on the GITD paint but it came out pretty thin and patchy. The GTID paint dries clear (more or less) so it doesn't hide the poor primer coat. Next time I'm just going to get some proper white paint and do it right.
    LASERS!!

    1x Homemade 500mW 405nm Projector
    1x Homemade 1.2W RGB Projector
    1x Lightspace Color Ray Series 6W RGB
    2x Lightspace Venus 2W RGB

    ZPL Lighting www.zpllighting.com

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