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Thread: 6W RGB Laser Build - UK

  1. #61
    Join Date
    Feb 2013
    Location
    Toronto, Canada
    Posts
    33

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    Hello,

    I have been following this build and would like to know if there has been any progress.

    Cheers!

  2. #62
    Join Date
    Jan 2013
    Location
    Kenilworth, UK
    Posts
    44

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    jjspike,

    Got a few bits now and after visiting UKLEM I think 6W is plenty powerful (the 4Ws on show were great). So I am going to be simplifying the build and running the diodes well within recommended current ranges, therefore no TECs etc.

    Due to work I am unlikely to get much done on this now for a few months, but will continue picking up parts ready.

    Dupe...

  3. #63
    Join Date
    Feb 2013
    Location
    Toronto, Canada
    Posts
    33

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    Quote Originally Posted by djdulux View Post
    jjspike,

    Got a few bits now and after visiting UKLEM I think 6W is plenty powerful (the 4Ws on show were great). So I am going to be simplifying the build and running the diodes well within recommended current ranges, therefore no TECs etc.

    Due to work I am unlikely to get much done on this now for a few months, but will continue picking up parts ready.



    Dupe...
    I too am collecting parts and experimenting as I find the time. Keep us posted as you advance your build. I'll start a build thread once I figure out what I am doing.

    Cheers!

  4. #64
    Join Date
    Jan 2013
    Location
    Kenilworth, UK
    Posts
    44

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    Its been a while, had a few other projects over summer, but now winter setting in I am back on the laser. Ready to start doing the optic path now so will be calculating my required lens etc. Should have my diodes in a week or so, just ordered with DTR.

    Will get some photos added once I get re-started....

    Dupe...

  5. #65
    Join Date
    Nov 2013
    Location
    St George UT
    Posts
    116

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    Just found this thread- I'm working on a similar project. I'm using FlexMod driver (DTR), but I found you need to use a higher voltage supply for the green diode (12V). Are you using this laser for scanning?
    As my project progressed, I had a rude awakening- the rise and fall times of each laser is different, so I'm working on a delay circuit similar to the one Pangolin published to solve this. My images had nasty coloured "noses" and "tails"- VERY noticeable during blanking.
    I'm interested in how your optical chain is working. Getting a nice round beam, especially with red diodes is a problem, my current dilemma. Any help would be appreciated.
    Tip- don't forget the Lasorbs (also Pangolin)- I lost my blue diode due to some sort of spike. Cheap insurance. DTR also sell a diamond based heat sink grease that is great- it doesn't dry out like the white paste does.
    Last edited by glorocks; 12-22-2016 at 18:02. Reason: more info

  6. #66
    Join Date
    Jun 2007
    Location
    Monroe, Mi USA
    Posts
    815

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    D-Lux....How is the build coming ???? I remember my first projector !!! Took 2 years to build !!! Many other projects suck money....taking away from funds for optics and such !!! That is just the way it is with the majority of us !! Well...there are a few exceptions !!
    .
    Anyway....this is the thread which inspired the " Donk " Axiom !!!Yeaaa...priceless !! And....I see I was searching for a NUBM07E driver solution...back in May....Sheeeze.....continue to put up with " CRS " syndrome !!!
    .
    Glorocks...Thanx for the tip re DTR thermal paste ! As far as the Red's.....well...they continue to be a PITA....but....we have eliminated the side wings....and Mr.Planters has a video which shows how to use " Spatial Filtering " to eliminate the vertical wings....takes some space...but it lools like it works great.....But then....when the scanners start to swing the beams around....I see no vertical up/down tails....perhaps...I lack a...errr...
    " Golden Eyeball " hahaha
    .
    CDBEAM
    Last edited by CDBEAM; 12-22-2016 at 19:13.
    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 !

  7. #67
    Join Date
    May 2014
    Location
    Barcelona, Spain
    Posts
    437

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    Quote Originally Posted by glorocks View Post
    Just found this thread- I'm working on a similar project. I'm using FlexMod driver (DTR), but I found you need to use a higher voltage supply for the green diode (12V). Are you using this laser for scanning?
    As my project progressed, I had a rude awakening- the rise and fall times of each laser is different, so I'm working on a delay circuit similar to the one Pangolin published to solve this. My images had nasty coloured "noses" and "tails"- VERY noticeable during blanking.
    I'm interested in how your optical chain is working. Getting a nice round beam, especially with red diodes is a problem, my current dilemma. Any help would be appreciated.
    Tip- don't forget the Lasorbs (also Pangolin)- I lost my blue diode due to some sort of spike. Cheap insurance. DTR also sell a diamond based heat sink grease that is great- it doesn't dry out like the white paste does.

    Is that green NDG7475? If so, you can run the driver at 12V just for one diode. Just keep the mosfet cool (attached to big baseplate) because at this voltage it have to deal with about 11-15W heat dissipation (depending on current you run the diode)
    Better if you can supply about 7-9V. 12V is ok for two diodes in series.
    For rise-fall optimisation Stanwax colour-board is a perfect addon.
    Not a 'round' beam direct from multimode diodes. However, on P73, if you go with FL:2mm collis and expand to get 0,5-0,6mrad (cyls) you will almost match both axis in divergence. So you will get about the same 'line thickness' size in both X-Y when scanning.
    You also will get a fat beam in between 6-7mm however, so big mirror scan about 6,5mm aperture is required on this setup...PT-As, EMS, CT.
    If you want almost 'round' beam profile from P73 keeping beam size <5mm for fast scanner, you must apply aggressive spatial filtering round pinhole. Or build a single mode array of 12-24 180mW 638nm diodes. Even those diodes have wings however (less than p73 of course). I can get much cleaner beam with SF on multi than single mode arrays.
    Another option, you know, cheap-simple just defocus spot a bit. Beam edges will become less sharp however.
    Last edited by jors; 12-23-2016 at 02:26.
    Jordi Luque


    AtenLaser.com
    Barcelona

    "Let there be light"

  8. #68
    Join Date
    Jan 2013
    Location
    Kenilworth, UK
    Posts
    44

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    Thanks everyone for the support so far...
    .

    So I am back on the build now properly, drivers ordered (BBE) and I am about to order some more G2 lenses from DTR. I have a few questions for you fine people:
    When wiring up the laser diodes I look at the data sheet, then check the forward bias voltage (like I would for a diode), if both the forward bias results and the data sheet match then I am good to go. With the reds (Oclaro HL63193MG 638nm Red) this method worked although the bias at 1.2V was a little odd. Wired up and tested on lab CC PSU, all good.
    .

    Next came the NDG 7475 and NDB 7875, bias voltage and data sheet do not match, checked the max reverse current and tested. No output so reversed and output once I got the confidence to push the current up to 200mA or so. The data sheet was correct; testing forward bias gave around 0.7V so why is the diode then wired opposite to this?
    .

    One of my diodes now has no measurement (open cct) on both forward and reverse, but still works, I assume I have maybe fried the protection cct?
    Whilst everything works fine I want to understand this, any thoughts?
    .

    Next is the collimating lens, I have 1 G2 from DTR so far for testing, the lens is a little loose in the brass tube housing, do I just need to tighten this up or is this by design to allow for expansion or something (shake in hand and the glass rattles in the tube).
    .

    Also, just for my understanding, when the lens is being screwed into the diode mount it tightens for the last 4 or 5 turns before in position, are the threads tapered or something so they stay put once set (DTR G2 and Daves copper mounts)?
    .

    I was going to add a little PTFE tape or something to ensure they don’t move, but this may not be required?
    .

    Finally, collimating lens tool to aid screwing in, ideally tube form so it can be adjusted whilst still observing the beam. Thorlabs seem to have some, anyone else?
    .

    Thanks,

    Dupe…

    We have light... by Simon Redfearn, on Flickr
    Last edited by djdulux; 01-12-2017 at 04:11.

  9. #69
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

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    Here are some answers to your questions, but maybe I will miss a few topics.

    The bias for these diode lasers is what is typically necessary to achieve lasing threshold. The process of generating emission requires sufficient potential across the junction so that photons of the wavelength that the material and the cavity are designed to amplify are produced. The polarity must be strictly maintained because unlike a typical rectifier diode, the constituents of the junction are electrically delicate and only a few volts in "the wrong direction" will destroy the junction. Any potential exceeding the required bias should me minimal (a volt or two is plenty).

    The diode laser is only very slightly current limited and as the bias voltage is approached and exceeded, the current that it draws is close to exponential and it will destroy itself long before you would be able to react and limit the current. That is why a current limited power supply (driver) is required.

    The required bias voltage will need to be increased a little, maybe as much a 1.0 V as the current is ramped from threshold levels to maximum operating levels. As the diode warms, the required bias voltage will decrease (run away potential here) while the bias will need to be increased as the diode cools. I have found the P73 diodes need as much as an additional 1.5 V at liquid nitrogen temperatures.

    Using Teflon tape is actually a very useful technique. The thread fit on most of the diode mounts is so loose that the collimator lens will not remain where you adjust it. The amount of tape is actually quite tricky. You will probably have to try a segment, screw in the cylinder, discover that you need a little more or less and then retry. The difficulty is that when you begin screwing in the cylinder it will gradually become tighter and tighter. Enough tape when you begin will turn out to be too much when you approach the correct depth. Don't over tighten to force it there. Remove the cylinder, clean off the few threads of tape that remain and here a tiny, very sharp, jewelers forceps is a real help. Cut a shorter strip of tape and repeat. Once you have the right length, it will generally be the right length for all the mounts from the same lot (generally).

    My favorite tool for lens adjustment is an X-acto knife blade; the one with the rectangular, chisel blade straight across the end. I grind down the cutting edge until the thickness of the parent material (no wedge). The thickness matches the notches in the cylinder wall. I use two widths. The larger is significantly wider than the cylinder and will allow the cylinder to be quickly screwed in up to the surface of the block. A narrower blade (you may have to grind down a blade until this width is just small enough to tit within the threaded hole and this keeps it from slipping out of the notches as you continue to screw the cylinder further in. Fabricating these tools can be done by hand using a flat sheet of 150 grit sandpaper lying on a lab bench . One major advantage of these tools is that they can be used in the X-acto handles or be removed and used directly with your fingers and this allows you to fine adjust the lens after the mount has been installed and the clearance in front is often very limited by down stream optics.

  10. #70
    Join Date
    Jan 2013
    Location
    Kenilworth, UK
    Posts
    44

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    Hello again, slightly embarrassed that its been 2 years since last here. Not sure what happened to the time! I have re-started the project, and plan to get the optical paths put together over the next few days, made a good start last night. Took a while to remember what everything was, but making progress.

    Thank for the help so far,

    Dupe...

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