Stoney's First Build - 0,6W RGV with harp mode!

[Stoney3K]

I hope nobody sues me for bumping this thread with an update every week or so



Got some nice pieces of metal fitted today, we're getting closer and closer to the bright, white light ... The dichro mounts were a bit of a puzzle to get in right though, the beam from my green kept hitting the side of the mount. I eventually turned the whole lot around and spaced the dichros a little more apart. My optics board looks more like Swiss cheese where the dichros are now...



The white plasticky bits you see in the photo are actually white plasticky bits. . They're from a 5mm thick polypropylene cutting board, I needed some temporary material on the cheap. Although it's easy to machine (I think I may have accidentally broken the hacksaw land speed record...) it's also pretty soft and a worthless heat sink. But hey, you can't really go wrong with a pint's worth of material! I might consider upgrading them in the future, but for now, they're OK to toy around with. Gosh, this would be so much easier if I could CNC everything out of billet aluminum...

I haven't mounted the actual mirrors yet, I'm going to leave them in the packaging to prevent damage until I have something I can bounce off them ... for the red and Bluray mounts, I've got an old Socket A heat sink that's a solid block of Aluminum with fins, which I intend to trim down and cut a 12mm hole in it where the module goes.

Meanwhile, I've ordered a threesome of Flexmods (still have to get Lasorbs) and I now have plenty of time to get my DAC fixed. Most of the parts are there, I still need a bunch of relays for the interlock. The last connector bits for the galvo amps will be in by tomorrow, which means I finally have X/Y scan capability and TTL blanking on the green, so I can get a few videos up. Might have the DAC ready for paint next week!

[Stoney3K]

Time for this week's update...

Got some improvised diode mounts up today for the red and Bluray, made from an old AMD processor heat sink. I just drilled a 12mm hole into it, and made a little tapped hole so it can take a set screw to hold the diode in place.





Venkman said to me: "DON'T CROSS THE STREAMS!!"

So I did, and threw some dichros in (Courtesy of Laserwave) so I could get some nice yellow...





Looking down the beam to peek at the far field alignment.

Unfortunately, my red didn't seem to survive the ordeal of alignment, and it died when I was doing the third attempt of aligning all three lasers for some white (the red with 405 made some tremendous magenta, though!). I did figure out what the problem was with this red and my previous Bluray though:

The driver circuit provided by the eBay supplier (bantdled) seems to heat up considerably when it's running at the rated current and supply voltages over 12V. The potmeter in the circuit is wired as a series resistor and therefore takes the full force of the laser's current, and when the pot heats up, its resistance drops and it raises the LD's current. A recipe for disaster, since the LM317 has quite a beefy heatsink on it, but the pot and the 1ohm sensing resistor have to make do with their plastic casing.

My new Bluray seems to work fine, I deliberately dialed the current down a little to prevent it from crapping out because of a faulty driver.



A little green is present in the beam here, but not much (the beam looks more like cyan in real life).



Here's mixing some cyan with the green cranked halfway up. When the green is all the way open at 50mW, the 405 is barely visible.



And here you can see what's happening: I didn't change any of the driver settings and let everything cool down for 10 minutes, and switched it back on. The Bluray was already getting pretty warm, so when it cooled down, it put out the power it was supposed to, mixing with 25mW green for some cool blue (almost Argon-like, whee! ). Can't wait to get a new red and do some white shots. Note that the color is a little off from reality, as my camera seems to have 405nm for breakfast. It took some serious flares from the galvo mirrors where the beam wasn't even spilling. (Luckily, no direct beam hits though)

I've received three Flexmods in the mail today, and I won't do any further experiments with the LD's active before I have the Flexmods wired up and adjusted.

I still have some components to order from RS, to finish up the DAC and enable the projector to run ILDA input. I'll try to salvage some red from a stack of DVD burners I have lying around here and there, since I have a few Aixyz mounts to spare now.

[Stoney3K]

Since my 650/660nm died out on me on previous experiments, I had a look around and pulled some coherent from an old DVD burner:



It had two diodes in it which were combined through a PBS, before being bounced upwards to the pickup assembly. I still need a good way to figure out which diode is the red one and which one is the 790nm IR (aside from firing them both up).

I'll see if I can complete the wiring of the Flexmods for the green and Bluray this week, and do some baseline adjustment with the red in place. I still need some decent mounts for the red and Blurays, the home-made mounts work but are not really the stablest when it comes to keeping them in place.

The red will probably be a temporary fix, since I got it for nothing I don't care if I screw it up again. And since those reds are seriously dirt cheap these days, adding more power is a complete snap.

When all goes well, I'll have access to a more professional machine shop near the coming Summer (I'm tagging along with a new automotive company), which will probably mean a new projector in the one or two Watt range.

[shobley]

>When I have that done, time for a demo video that will wipe Stephen Hobley off the face of the planet.

Oooooh them's fighting words!


<Tries to imagine some kind of Vader/Kenobi battle but with laser harps>

Actually I've often described the laser harp as a kind of lightsaber type project, in that to own one, you have to build it yourself.
(Unless of course you go on Jools Holland's show and play the Stylophone, then I might build one for you - http://www.youtube.com/watch?v=4cHX-znop8Q)

[Stoney3K]

OK, tiny little update here:

I found a box to mount the whole projector, which started its life as a $20 CD case, but has plenty of room to mount a lot of stuff in.



I'm keeping the lid hinges, and mount a plexiglass plate on top so I can use the excess space in the lid to store small trinkets like cables and a sound card DAC. A case intrusion interlock (microswitch) will keep prying eyes out of the box when the laser's running.

Still to fix, holes for the apertures (one on the front for regular shows, one on top for the harp mode), connector panels and other small things. And I need to get a replacement LOC to get the red working again.