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DIY Red #2

flogged

flogged

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Jul 8, 2007
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Just finished another epoxy wonder. This is my second DIY red.. I'm addicted to building these things now. Haven't toasted a diode yet thanks to the expertise gleaned off this site.

For this one I used a RS project box, about 6x4 inches. All the parts for the driver circuit I got at RS also.

For the diode housing and optics I'm using the Meredtith LDC1 + mounting block (as heat sink). see here: http://www.mi-lasers.com/cgi-bin/shopper.cgi?search=action&keywords=diode_optics

I ordered a special hard to find thermal adhesive to assure the diode will be able to quickly wick heat out. I got the arctic silver epoxy.. here:http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

This adhesive served two very important purposes. First it keeps the diode centered in the optical path, as well as preventing the diode from squirming and rotating while focusing the lens. Second it assures that heat can quickly escape the diode to the case housing and heatsink. In order for the Sony 16x diodes to work in the Meredith housing they must first be press fit into a small adapter (the housing is meant for 9mm diode cans, the Sonys are 5 mm). Turns out I had to do a little scraping and sanding before the diode would sit snug and flush in this adapter. I then finished the work by applying a few nano dabs of thermal glue to make certain the diode was tight in the adapter. The adapter (a little brass bit) I then thermal glued to the back of the housing, centered. I found unless I do this the adapter does not stay centered while focusing the lens. With this tedious bit of work complete I can now focus the laser perfectly and the diode does not squirm. A little less than 180 degrees of turning will focus from infinity to under 8 inches.

I'm using the Meredith housing with the acrylic (not glass) lens. While this lens may absorb a bit more light than the glass lens it really focuses to a tight spot!! Ideal for burning. At 25 feet the spot is tiny, just a few mm on a side, and very clean - just the diode wings + spot.

I metered this one up to 240mA. While I don't have a laser power meter I can tell you how it's burning. I'll be testing the balloon range later this week, but for now balloons out to 25 feet die instantly. It will light wooden safety matches (sharpied) out to 7-8 feet (after getting the focus correct).

A few pictures.

The completed laser:
DIY_red2_5.jpg


I took this picture while I was metering the power for the first time, after turning on the completed laser and having it work (yes!!).. Unfortunately I was only able to meter up to 200mA before the pot maxed out. Hmm. I was forced to put another 10 ohm resistor down to get the current up to 240 mA.

DIY_red2_1.jpg


Closup of the inside. Meredith housing, RatShack parts, 4 AA nimh batteries.

DIY_red2_4.jpg


FIrst task, burning a hole through the top of the case from about 8 inches.

DIY_red2_3.jpg


Well, the parts cost me a bit.. Let's see, all the parts for the regulator + the project box came to about $20.00 at RS. The Meredith housing + heatsink was $30.00. And the diode was about $20.00... so roughly $70.00 in parts + some tedious work, but I'm happy with the pointer. At 240mA it's probably well over 150mW power output. It burns like it at least.
 
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Nice work! I like those Meredith housings, but the AIxiz are more in my price range. BTW, if you have a Fry's Electronics near you , they sell that Thermal epoxy for $10 and have it in stock, i just bought some there. That stuff works really good.
 
desslok said:
Nice work! I like those Meredith housings, but the AIxiz are more in my price range. BTW, if you have a Fry's Electronics near you , they sell that Thermal epoxy for $10 and have it in stock, i just bought some there. That stuff works really good.
Click to expand...

Thanks. I'm happy with how this one turned out. The first one I made I was a bit too rushed.. I didn't think it would work.

I hope the thermal glue will extend the life of the diode by keeping it a bit cooler than it would be otherwise.

One area that could use more experimentation would be the optical side of things. That's half the equation for a burning laser -- getting a tight focus. I was thinking for my next experiment I would use a collimator lens assembly. Essentially this uses more than one lens - typically three - to reduce the divergence closer to theoretical limits. You loose a bit of power because the beam is going through more glass, but you gain much a tighter spot at a distance. It may be possible to make a 100 foot balloon popper with a better lens assembly. Several people offer these, including Roithner.

With the Meredith acrylic lens my latest burning laser (like the one before it) will easily pop balloons out to 40+ feet. It's essential you get the focus as tight as possible. Just went out into the hallway of my apartment and popped a large 'helium grade' blue balloon at 40 feet. It took over 5 second but it went off like a bomb. BOOOM. For a single fast lens the Meredith acrylic works very well for burning.
 
Nice laser man, I also bought a ratshack project box, but I messed it up trying to get rid of all those plastic things inside by cutting them and melting them with a soldering iron since they were getting on the way of mounting some stuff.
 
flogged said:
With the Meredith acrylic lens my latest burning laser (like the one before it) will easily pop balloons out to 40+ feet. It's essential you get the focus as tight as possible. Just went out into the hallway of my apartment and popped a large 'helium grade' blue balloon at 40 feet. It took over 5 second but it went off like a bomb. BOOOM. For a single fast lens the Meredith acrylic works very well for burning.
Click to expand...
Wow, 40 ft. You have a much steadier hand than me. At more than a few feet, it looks like I need a drink I'm shaking so much. I can only hold it steady enough within 6 ft or so. THat is why I made another post about making a "turbo" button to keep the laser on at low power, then jump to full power when I have hte beam focused and targets. Yeah, I still don't really understand how all the lenses work, but I've only messed witht he Aixiz modules so far.
 
desslok said:
Wow, 40 ft. You have a much steadier hand than me. At more than a few feet, it looks like I need a drink I'm shaking so much. I can only hold it steady enough within 6 ft or so. THat is why I made another post about making a "turbo" button to keep the laser on at low power, then jump to full power when I have hte beam focused and targets. Yeah, I still don't really understand how all the lenses work, but I've only messed witht he Aixiz modules so far.
Click to expand...

That's one advantage of the 'brick' package - just flick the toggle switch and set it down. There's no way I could hold the pointer steady enough to pop a balloon at 40 feet. For all of my balloon pops I've been setting the pointer down on the floor.. so it's steady. Any movement and it will not work over 30 feet.

I'm hoping to do some more work on the optical side of things. Lots of places sell optics for laser diodes. I'm hoping to find a collimator lens assembly that gives me close to diffraction limited divergence. This will involve more than one lens and probably be a little expensive - about the price of an eyepiece for a telescope ($50.00). Let you know if I can find anything.
 
flogged said:
[That's one advantage of the 'brick' package - just flick the toggle switch and set it down. There's no way I could hold the pointer steady enough to pop a balloon at 40 feet. For all of my balloon pops I've been setting the pointer down on the floor.. so it's steady. Any movement and it will not work over 30 feet.
Click to expand...

I'm actually thinking of building my next one into an old Canon digital camera case I have laying around, then I can mount it one of these Gorillapods, they act like tripods, but also "grab" onto just about anything:

http://www.joby.com/products/gorillapod/
 
Goddamn, I've created some sort of balloon popping monster!! Wish I had a vid cam to show this.

I can reliably pop balloons out to 50 feet! In fact, I don't even know what the limit is yet. These are 9" blue 'helium quality' balloons, which I sharpie.

I saw Pseudo's balloon popping vid, and his RPL-300 took over 20 seconds to pop a balloon at 30 feet.. seemed to do a better job burning the wall. :)
here:http://www.youtube.com/watch?v=nzKZZc7IXxE

At 50 feet my latest pointer will take out a balloon in under 5 seconds.

Next stop 60 feet. Though I need to stop experimenting for a while in the apt. hallway. Annoying the neighbors.
 
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