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Thread: First 445nm build, new here

  1. #1
    Join Date
    Jan 2015
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    9

    Default First 445nm build, new here

    So ordered a Nichia NDB7875 445nm 9mm Laser Diode from dtr off amazon, have been researching this most of last year and was going to buy a L-cheapo kit but decided once I built my first few pointers to diy.

    My first pointer was pht803t out of a hd dvd xbox drive, it shattered extracting or somewhere inbetween, next i did a ps3 diode and its still working (love the violet), then i pulled a red one from a lightscribe dvd burner, fed that with the circuit thats posted everwhere with the 2x 10ohm resistors and was burning tape and stuff.. ended up cranking it up as high as i could and burnt it out after a few hours, was kinda relieved to have it gone tho since i don't have red laser glasses. also made a cd-r diode that worked. got a feel for the driver making and how they work.

    Been reading up on drivers and about the diode itself as it will be used on a 3d printer or a cnc once its finished for light cutting/engraving.
    was thinking of using the driver from L-cheapo for this diode
    here's the circuit : http://robots-everywhere.com/re_wiki....LCheapoSchems

    really here looking for any kind of input on a the driver since it will be fed off the 3d printers rumba board from a mosfet
    have all kinds of resistors/cap/pots and 1n4001's to test stuff with, just don't want to break this diode right away.
    also have blue/green safety stuff!

  2. #2
    Join Date
    Oct 2012
    Location
    Germany
    Posts
    1,055

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    ... use a really big/oversized cooler, don't let heat the diode above 30degC and apply max 90% of the rated max. current ... and the diode will last 'for ever' ;-)

    Viktor

  3. #3
    Join Date
    Jun 2010
    Location
    Australia
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    3,729

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    Quote Originally Posted by VDX View Post
    ... use a really big/oversized cooler, don't let heat the diode above 30degC and apply max 90% of the rated max. current ... and the diode will last 'for ever' ;-)

    Viktor
    That is a very long time! Roughly 1/0 seconds.
    This space for rent.

  4. #4
    Join Date
    Jan 2015
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    9

    Default

    diode came today, went to do a quick test before work... knew it wasn't a great idea but had to see it.
    anyways connected to diode to the v-out instead of the adj so it got fed 6volts but only around 250ma's.. light up for a bit then dimmed. turned off then on again, went bright and dimmed.. did that a couple times before i put it away and went to work.
    was running a 9v battery that read 7.4v on a mm, so i think its almost dead.

    hopefully i didn't ruin my diode.. guess i won't know till later

    tried again with 5v and about 200ma's.. lights dim unless focused, idk if its safer playing with it at lower currents or what.. honestly think i'm being an idiot experimenting with this diode. its prob a led by now, would build the driver i had planned but waiting on the lm338
    btw i'm a total noob to laser stuff and only built my first laser a week ago.

    pretty sure i ruined it... patience would have helped, this sucks.

    last edit on this post.. figured oh well and hooked it straight up to a 5v 1a power power supply, bam! a bright blue beam! was kind of amazed at this thing.. focused it in and cut a red envelope in half in short work. only had it on for maybe a minute..
    didn't have glasses on.. jumped back on my computer right away and noticed a yellow ghosty spot image on a white screen.. oh noe.. well it went away after a few minutes and hopefully there's no permanent damage, but that will be the first and last time i try to fire it up without glasses on..

    all in all the experiments all worked out in the end and that thing bad! could see the beam visibly touched it and it f'in hurt...

    now to build or buy a correct driver, holy crap though this thing is nuts.. really want to finish my cnc now.
    Last edited by cor5151; 01-07-2015 at 06:23.

  5. #5
    Join Date
    Apr 2007
    Location
    Costa Rica
    Posts
    521

    Default

    And so it begins. Have fun - be safe!

  6. #6
    Join Date
    Jan 2015
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    9

    Default

    I will!
    after spending the morning researching vision stuff and laser hazards It occurred to me how much i've taken being able to see for granted without ever really thinking about it.
    did a few more test cuts/burns with goggles, but don't plan to use it again until there is a proper enclosure on the printer or cnc.
    the yellow spot kinda reminded me of snowboarding all day when i was a kid and being around a welder.
    only other time i've ever seen that yellow spot.

  7. #7
    Join Date
    Feb 2011
    Location
    New Hampshire
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    3,513

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    Cor,
    You scare me little fella. Both the violet and the 445nm lasers are truly dangerous. A major concern with your initial experiments is that you approach it with "let's just try this and see what happens". That's fine from the diode's point of view, it's just money, but the beam is like a cobra; it attracts your attention, so that you focus the most valuable part of your retina right on the brightest part. Color inversion and after images are close to the damage threshold and if the surface is not truly homogenous then there could have been hot spots within the image that could have already caused damage. Some damage is reversible, but some is not and the brain tends to compensate, so that you are less aware of it (like a smudge on a pair of glasses).

    Also, if you intend to actually use the diode in a laser cutter then what of the enclosure? Will it be truly opaque or selective to the blue wave length? I ask this because when these are functioning or you are making adjustments you will need to see what is happening, but safely. You certainly need a driver that will allow you to control the current precisely, if you you will be using this for engraving. This driver will also allow you to work with the diode at powers just above threshold and have shut down features that operate when you open an enclosure. You should not depend on a dying battery to regulate voltage.

    If you have just begun to work with lasers one week ago(since your initial pointer builds) then I strongly urge you to put this on hold for a little while and spend some very valuable time on this forum. The hobby/profession working with lasers and photonics can be very rewarding and aside form the obvious safety concerns you will come to realize that knowing better what you are doing will give you much greater control over these systems. They will work better and you will be ready to advance to more power, different wavelengths, better beams and uses you haven't thought about before. This forum is like no other I have come across (we've all seen LPF). There are numerous members here who truly enjoy educating and giving hints and guidance and they will help, but one big turn off is when the experimenter seems to be cavalier about safety.

    Welcome!

  8. #8
    Join Date
    Jan 2015
    Posts
    9

    Default

    Thank you for your concern planters.
    I have put it away and won't be using it again anytime soon, I honestly never seen something quite like it before and you are right about it being like a cobra, that's what happened to me when it first powered on. I tried to shield my eyes and not look at it but couldn't help it.
    I only noticed the yellow smudge against a bright white pc screen for maybe a minute and it did scare me, not to mention being kind of a hypochondriac.

    I've been thinking of the enclosure a lot since then, honestly didn't really plan to have one at first, but that has changed since realizing the power and danger of this laser diode.
    want to fully enclose it with solid walls and use a rpi camera/ webcam for viewing while cutting and a green or blue shielded part on front/side for setting the focus.
    Cnc table is going to be roughly 3'x4' I started a page on openbuilds here but haven't updated it in a while : http://www.openbuilds.com/builds/no-xp-cnc.1267/
    have finished most of the 3d models and need to finish printing some stuff, but going to print in nylon/pc to make it thinner/lighter/stronger also going to have to update for enclosure supports.

    Again I have a completely different respect for these lasers now than when I first received it. I was stupid and impatient trying to just see if it worked.. a mistake that may have damaged my eyes.

    I hope to make some interesting things and share my experience with this project with everyone here, glad I found this forum!

  9. #9
    Join Date
    Jan 2015
    Posts
    9

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    After a lot of searching this is one of the better things I've found on laser damage
    http://www.aao.org/publications/eyen...derForPrint=1&

    Figured I'd post it
    Could be avoided very easy just don't want some thing like this to ever happen to someone else on my behalf.
    I'm worried enough about abs/pla offgasses from the printers that I use exhaust fans and don't usually let anyone around when printjng/extruding.
    I should probaby take more care in my own safety.

    little update but its been 2 weeks vision is sensitive to light, and eyes iched+headaches for about a week, i mainly observed the dot with my right eye and kept the left shielded. headaches were intense though and made me think the photon overload caused some kind of brain injury because it was reminiscent of a concussion, also noticed a resurgence of my dyslexia speech and it may be caused by the eye injury but also seems more like the word blindness i had as kid.

    visual clarity seems unaffected and only due to light disturbances and sometimes blurryness of the right eye, possibly thinking it onset keratoconjunctivitis similar to ach eye

    well these things are super dangerous and observing the dot/beam without the correct safety glasses is asking for injury.
    I may have done a lot of stupid stuff in my life, but there's not to much i regret... this is close to being one of them.

    Also have been completely redesigning my cnc/laser cutter build to be a smaller dedicated fully enclosed laser cutter with multiple safety layers. had to scrap my designs and a few 12+ hr prints but there's no way one of these 445nm lasers should be operating where someone can accidentally look at it.

    after 3 weeks its hard to tell if it still is affecting my vision, the right eye hasnt been blurry since week2 and only noticable problem is going from bright rooms to dark and eyes adjusting might be slower.
    The headaches in week1 i'm almost positive were cluster headaches, its interesting to me because there isn't a known cause for them and i'd never had them before or since.
    i can strain my eyes trying to read fast scrolling texts on webpages and will cause slight irritation to the back of my eyes after a while so i think the retina is still healing.
    Last edited by cor5151; 01-29-2015 at 13:11.

  10. #10
    Join Date
    Jan 2015
    Posts
    9

    Default

    So after a long long time, my build is nearing completion, the Nichia NDB7875 is lasing with a 3a driver running analog through ramps with a little help from a lm317t.
    Driver here(i'm using r5): http://www.ebay.com/itm/3Amp-analog-...item25ad9bc913

    Its inside a small printed case and will soon be installed on MPCNC that is currently only 5-6"x26" but will soon expand to 26"x43".

    Really excited about finally trying some grey scale lasing with picengrave once i can buy it.

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    Still have my original unfinished build around that would be much more precise, but haven't been able to finish it and the MPCNC was such a great machine to build+cheap, recommend it!
    Last edited by cor5151; 09-27-2015 at 20:53.

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