200mW projector build

[janelo]

Hi folks,

since this is my first post, here's a quick intruduction:
My name is Jan, I'm a mechanical engineering student from central Europe. I've "played around" with lasers years ago (after I saw my first laser show at a local swimming pool ). I'm a big fan of diy, so I started building the usual lissajous stuff. Unfortunately lasers were really expensive back then so I eventually moved on to other projects. Other projects usually involved various electronics and high voltage stuff.

Only recently I discovered that green and blue laser diodes not only exist but are available at reasonable prices (not sure how I had missed this for so long). I figured it would be a great time to get back into the hobby and have some fun building a small projector, which brings me to the second part of this post (that will hopefully be more interesting than boring facts about me):




I wanted to build a projector for use in small rooms (essentially just so I could watch a few shows by myself).
I did not need a huge amount of power so I ordered a few diodes that would hopefully get me to roughly 200mW white:
- 660nm/120mW Ushio HL6545MG
- 520nm/50mW Osram PLT520_1_2_3
- 450nm/85mW Sharp GH04580A2G


I made diode mounts from 20x25mm (~0.8x1'') aluminium flat bar. Mirror mounts were made from aluminium angle stock and a piece of flat bar. The lasers were then mounted on a piece of aluminium plate. I added a small PCB to each laser diode to prevent mechanical stress from soldering wires directly to the diode terminals. I also added a shottky diode for reverse voltage protection and a resistor to (hopefully) mitigate damage from light ESDs.





The finished laser assembly and the galvo block were then mounted to a second piece of aluminium plate. The galvos are leftovers from a previous project. I believe the galvos are called "SP-20K", not really sure about that though.





I built diode drivers mainly from leftovers out of my parts bin. The third trimmer adjusts standby supression threshold (I just was not sure what value to set it to). I don't have active temperature control but given the low power of the diodes I figured it should be fine.





I also quickly designed a small interface board. It contains the usual differential to single-ended converters for the laser drivers. I also added a Atmel MCU to control the few bits of logic (shutter, interlock ...).






A few impressions from the "children" show from ILD:





And a few beams:




The finished projector turned out to be a bit bigger than anticipated - the next one definitely has to be more compact :P:

Attachment 56108

Future plans for this projector include adding a front panel (i actually have that already but can't cut a nice square hole at the moment) and some sort of scanner monitoring. I made a big mistake in not adding a separate shutter input to my diode drivers. The MCU can cut the power to the laser drivers, but I added so much capacitance so the lasers won't turn off immediately. With adding a safety circuit I'd therefore also have to either redesign my diode drivers (adding a shutter input) or my interface board (so the MCU can disable the lasers using the modulation input).

Jan

I hope the resolution of the photos is ok. If it's too large just let me know and I'll scale them down.

[edison]

What a fantastic build! Very clean and professional. I,m concidering doing a build with 638nm, 660nm, 405nm, 445nm 2x520nm with 60kpps scanners to learn software like quickshow or beyond. Good work!!

[JohnYayas]

That's pretty nice. I need something small and low powered like that. I need to do a new build.

[dchammonds]

Great work, you should consider building projectors for sale!

[lasermaster1977]

Very, very nice build. Well done.

[dkumpula]

That is a very nice build. I’m further impressed that you did all of the electronics from scratch and made your own mounts and such. It came out so clean as well. Bravo!

David

[kecked]

That’s a great setup. If you can put a set of 506 compacts in there. You’ll be much happier than with 20kps scanners. I shrunk mine to a 6” cube but David has done I think 2”x3” battery operated. Those are my favorite diodes. You might try finding some off spec 520 nm single modes operation closer to 530. The yellow is much better. Those low power opsl might work but they are a pain to keep stable.

my fav would be 660/647. 543. 575. 470. 450. Rgybv all single mode. But realistic 660/638/520/460. That 660 line is really amazing even if inefficient.

[janelo]

Thanks for the kind words, guys!

I,m concidering doing a build with 638nm, 660nm, 405nm, 445nm 2x520nm

Sounds beautiful! How would you implement the control logic for mixing all the different colors? Would this be handled by software?

I also really like the deep red 660nm provides. I must admit I haven't seen 405nm in person yet, definitely have to get a few diodes to play with.

If you can put a set of 506 compacts in there. You’ll be much happier than with 20kps scanners.

Absolutely, the 20K scanners are not great, especially for graphics (and I really like graphics). I was actually thinking about buying a new set of DT50s for this project but ended up just using what I had. Unfortunately swapping the scanners is not that easy at this point. I think the best way around this will be to just build another projector . I had lots of fun on this project so I'm definitely planning on building myself a 2nd projector when I find the time for it.

Jan

[kecked]

skip the 405nm unless you plan to do glow in the dark. better to go 460/445 or something like that. below 445 is not useful. it upshifts to 460 or so anyways.

get that 660 in there it matters. stay as far above 520 as you can 543 isn't common but its beautiful. a good dpss 532 will make a better yellow but diode modulates better.

too bad 575 isn't more available. you want to see a white! 575/445!!!

[edison]

462nm is damn beautiful. Can,t wait to build the first 12 combiner in a 462nm/445nm combo. That with a 12x 520nm and a 12x638nm/700mw will be crazy