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Thread: Basic steps in building a 445nm approx. 1000mW laser & output beam shaping/control??

  1. #1
    Join Date
    Nov 2010
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    Default Basic steps in building a 445nm approx. 1000mW laser & output beam shaping/control??

    Dear 445 Forum

    Please can you advise if there is any standard advice/basic steps regarding a self build 1000mW laser based on the 'typical' 445nm laser diodes? I have searched the forum, but have not found much.*I am fairly experienced in most of the aspects of using laser modules & electronics, but not in the actual 'building' of a laser module.

    From what I have learnt from these forums, YouTube & LaserpointerForums forums, the basics seem to be:-

    1) Ensure I have suitable safety kit, like goggles, anti-static mats/wrist straps, & a respect/knowledge of the safety considerations. Plus tools of course.

    2) Obtain an M140 laser diode, taken from a digital projector.seem to go for about 45 on eBay. Physically a fairly simple 5.6mm diameter metal can. Very static sensitive & make sure I don't touch where the beam emerges.

    3) press/fit the laser diode into a suitable housing. I keep finding reference to Aixiz Modules, so presumably these are round tubes with a lens at one end. Are they fixed lenses, or adjustable focus? Plastic lenses not upto the task of handling a 1000mW beam, so glass lenses preferred? Are there alternatives to the round Aixiz modules? But I guess these modules are good at holding the laser diode & lens in alignment, & conduct heat away to the heatsink? I have found there are kits and/or pre-assembled modules on eBay, in case I don't fancy handling a bare laser diode?

    4) Once fitted, connect a suitable driver to the laser diode. Due to the special engineering characteristics of the laser diodes, simple series resistors are not enough? Regulation, over-current protection are just a few requirements. I have found mention of Dr Lava Flexmod, but there seems to be many more of these on the market? Once fitted, the laser can be powered from a fairly simple regulated dc PSU or battery. Support the driver PCB so it cannot move/flex?

    5) Mount the Aixiz module/housing in a suitable heatsink, & cool with a small fan if needed. Could this be a lump of finned aluminium with a dia. 5.6mm hole? Heat transfer paste maybe, just like fitting a heatsink & fan to a PC microprocessor?

    6) Attend to the shape of the beam produced. I read that it is not always a collimated beam, but is elliptical. The output lens should help, but a pair of Anamorphic Prisms or cylindrical lens may help. But how is it best to get a beam of about 2mm with only 1 to 1.5 mrad of divergence? Especially if I want to combine it with my green DPSS laser module using Dichroic filters etc. a fat blue beam won't do will it? Also I'm not sure the mirrors on my XY Galvanometer pair would accommodate a wide divergent beam either.

    7) Don goggles, check all my hard work, check it again, get someone else to check it, before applying power (possibly current limited)?

    Is the above a concise summing-up of the process, or have I omitted important considerations?

    Also much of the advice relates to laser pointers which will only be on for 10 to 30 seconds. What I want is more of a module, capable of continuous operation as the blue in my RGB Laser projector (built to enhanced ILDA Standards). I understand if I run the laser at less than the 1000mW level, things may be easier in this respect?

    Sorry if this is not the right part of the forum, but I could not find a more suitable place to post it! I certainly don't want to upset anyone by asking for such rudimentary information. Also are the M140 laser diodes a more efficient buy than the others?

    Many thanks in helping a newbie with his first steps in 445nm laser design! I guess I am seeking a bit of a de-risk; hopefully I can avoid my own expensive mistakes, by asking for the considerable accumulated knowledge & expertise present in the Photolexicon Forums (that's you guys & girls).

    Simon B.

  2. #2
    Join Date
    Feb 2010
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    Melbourne, Australia
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    Default

    Hi Simon,

    Here's my advice in the context of your points above.

    1 - yes
    2 - yes
    3 - use a diode mount from Dave at lasershowparts.com (user "dave" here on PL). Get an O-Like 445nm, or 405-G-2 lens from laser66 with a lens barrel from dave - either which will fit Dave's mount. These are glass and provide good beam specs for our needs. Use a laserbug from 300EVIL or get a suitable diode plug to save soldering directly to the diode pins.
    4 - yes, FlexMod P3 or other suitable driver (search here for 445 + driver). No need for resistors if only one diode is used. A 6-24v DC switch mode power supply (SMPS) is best and dependent on your chosen driver. Yes, everything should be mounted properly.
    5 - Diode mount should be attached to a good baseplate. This may be enough to keep diode temperature/output power stable, or use a Peltier TEC with a thermistor and simple driver to keep the baseplate or diode mount cool (search here for TEC driver by weartronics).
    6 - Use anamorphic prisms which can also be bought from dave. It's either narrow and divergent or wide and less divergent, the scanners will benefit from a narrow beam regardless of divergence. The key is to get a far-field beam size and ooverall beam divergence that matches your green and still fits on your scanners. Getting a near-field beam size under 4mm can be tricky unless you use a 2:1 reverse telescope to halve the beam width which doubles the divergence. As the divergence may be lower than your green, this might be exactly what you want to do. I haven't bothered with this. The beam starts fatter, but after a short distance looks the same width. Look at the 2nd link below for precise beam specs with the lenses and prisms I've proposed.
    7 - yes. Though reading and following the driver's instructions should prevent any over-current mishaps.

    My steps are:

    Wire up laserbug or diode plug and driver board according to instructions. Test bias (modulation = 0v) and full-power (mod = 5v) currents according to instructions, though set full-power to less than half what you plan to use, say 300 to 400 mA. After this, short the output wires to discharge the driver's capacitors.
    Keep the diode static free. If you receive it soldered across the anode and cathode and desolder it, use a jumper to keep them bridged prior to installation.
    Prepare diode mount for diode, lining the diode seat with a very little heat transfer compound.
    Ready the diode, remove solder etc and clean pins keeping them straight and as long as possible (under ESD-preventative conditions).
    Install diode in mount choosing rough orientation based on spare pin (North or East for example). Depends on mounting orientation of prisms relative to diode mount.
    Screw back plate in almost all way, leaving a little slack to allow some rotation of the diode with little force.
    Again and just before the next step, short the output wires to discharge the driver's capacitors (just in case there's still power in the driver).
    Attach pre-wired laserbug or diode plug to diode.
    Screw in lens part way (build lens into barrel if going the 405-G-2 route).
    Apply power to the driver and increase mod signal to 2v, you should see the diode come to life. Increase to 5v mod.
    Adjust the focus of the lens until the diode produces a 1 meter stripe on the wall.
    Turn the diode until it is exactly aligned with the diode block according to the orientation you need for the prisms.
    Focus the lens until the far-field beam is as small a line as possible.
    Detach the driver output wires from the diode and short the output wires to discharge the driver's capacitors.
    Test bias (modulation = 0v) and full-power (mod = 5v) currents according to instructions, though set full-power to the full current that you plan to use, e.g 800mA. After this, short the output wires to discharge the driver's capacitors.
    Re-attach pre-wired laserbug or diode plug to diode.
    Mount your prisms according to zoof's template
    Orient the prisms
    Put the whole lot in a housing
    bingo, job done!

    Read this... http://www.photonlexicon.com/forums/...ion-correction

    Check out Dnar's picture here where he has done exactly what you want to do. The rest of that thread shows the prisms in use.
    Last edited by taggalucci; 04-24-2012 at 17:24. Reason: Added missing steps including good suggestions from Hobbybob :)

  3. #3
    Join Date
    Jul 2009
    Location
    The Netherlands
    Posts
    1,458

    Default

    Quote Originally Posted by taggalucci View Post
    Hi Simon,

    Here's my advice in the context of your points above.

    1 - yes
    2 - yes
    3 - use a diode mount from Dave at lasershowparts.com (user "dave" here on PL). Get an O-Like 445nm, or 405-G-2 lens from laser66 with a lens barrel from dave - either which will fit Dave's mount. These are glass and provide good beam specs for our needs. Use a laserbug from 300EVIL or get a suitable diode plug to save soldering directly to the diode pins.
    4 - yes, FlexMod P3 or other suitable driver (search here for 445 + driver). No need for resistors if only one diode is used. A 6-24v DC switch mode power supply (SMPS) is best and dependent on your chosen driver. Yes, everything should be mounted properly.
    5 - Diode mount should be attached to a good baseplate. This may be enough to keep diode temperature/output power stable, or use a Peltier TEC with a thermistor and simple driver to keep the baseplate or diode mount cool (search here for TEC driver by weartronics).
    6 - Use anamorphic prisms which can also be bought from dave. It's either narrow and divergent or wide and less divergent, the scanners will benefit from a narrow beam regardless of divergence. The key is to get a far-field beam size and ooverall beam divergence that matches your green and still fits on your scanners. Getting a near-field beam size under 4mm can be tricky unless you use a 2:1 reverse telescope to halve the beam width which doubles the divergence. As the divergence may be lower than your green, this might be exactly what you want to do. I haven't bothered with this. The beam starts fatter, but after a short distance looks the same width. Look at the 2nd link below for precise beam specs with the lenses and prisms I've proposed.
    7 - yes. Though reading and following the driver's instructions should prevent any over-current mishaps.

    My steps are:

    Wire up laserbug or diode plug and driver board according to instructions. Test bias (modulation = 0v) and full-power (mod = 5v) currents according to instructions, though set full-power to less than half what you plan to use, say 300 to 400 mA.
    Keep the diode static free. If you receive it soldered across the anode and cathode and desolder it, use a jumper to keep them bridged prior to installation.
    Prepare diode mount for diode, lining the diode seat with a very little heat transfer compound.
    Ready the diode, remove solder etc and clean pins keeping them straight and as long as possible (under ESD-preventative conditions).
    Install diode in mount choosing rough orientation based on spare pin (North or East for example). Depends on mounting orientation of prisms relative to diode mount.
    Screw back plate in almost all way, leaving a little slack to allow some rotation of the diode with little force.
    Attach per-wired laserbug or diode plug to diode.
    Screw in lens part way (build lens into barrel if going the 405-G-2 route).
    Apply power to the driver and increase mod signal to 2v, you should see the diode come to life. Increase to 5v mod.
    Adjust the focus of the lens until the diode produces a 1 meter stripe on the wall.
    Turn the diode until it is exactly aligned with the diode block according to the orientation you need for the prisms.
    Focus the lens until the far-field beam is as small a line as possible.
    Mount your prisms according to zoof's template
    Orient the prisms
    Put the whole lot in a housing
    bingo, job done!

    Read this... http://www.photonlexicon.com/forums/...ion-correction

    Check out Dnar's picture here where he has done exactly what you want to do. The rest of that thread shows the prisms in use.
    Hi Simon,
    I would follow this very thorough write up to the letter, as it's very clear to understand but want to add one more step, that cost me 2 blue diodes:
    After you adjust the current (Bias and modulation), i would power off the driver and SHORT the leads to the diode (so after adjusting and BEFORE soldering the wires to the diode. I didn't do this and the the residue current spikes and killed 2 of my blues.
    After shorting the driver to releave the capacitors of their charge i never had this happening again !
    So please add this step !

    Kind regards,
    Dimitri
    I didn't fail !
    I just found out 10,000 ways that didn't work.

  4. #4
    Join Date
    Feb 2010
    Location
    Melbourne, Australia
    Posts
    1,106

    Default

    Thanks Dimitri I've updated the post with your suggestions.

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