My DIY Red Shoebox Laser

I finally completed my DIY red burning laser. Been working on it feverishly all day, and it's finally done. It's a hack and it's not going to win any beauty contests but I'm proud of it.

I ordered two of the Sony diodes from the Senkat group buy months ago (in August) and I'm happy to say no diodes were killed making this laser. I got lucky. So I have a spare bulb if the current diode dies.

I used Daedal's circuit (see this thread: http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612) to drive the diode. I ordered the diode housing and optics from Meredith (see:http://www.mi-lasers.com/cgi-bin/shopper.cgi?search=action&keywords=diode_optics).

Once assembled I slowly turned up the pot while metering things with my old radioshack analog multimeter. It was so satisfying to see the diode come to life and slowly brighten as I increased the current. I carefully metered it up to 225 mA. I decided to stop just short of the 250 mA mark. Though I could easily push more than 300 mA of current through the diode by adjusting the pot I'm going to be a little conservative. 225 mA of current should put the power output well over 100 mW.. possibly over 150 mW if the diode is efficient. It certainly burns like a 100+ mW laser.

Below are couple of pics of the laser box. I assembled the laser housing using the covers from an old hardcover book. An X-acto knife and lots of epoxy glue completed things.





Close up of the innards. Yeah it's messy. I just wired the circuit around the pot. I'm using NiMH batteries because they can easily supply the needed current (unlike alkaline batteries) and they have a very flat discharge rate. The most sketchy part when soldering things up were attaching some 20 gauge copper wire directly to the diode legs to increase their length. Not fun but I did it.



I'm not satisfied with the Meredith housing. Whenever I focus the lens the diode sometimes turns also so I have to be careful. I'd like to look into other options for my next laser. Visually the laser is bright, though it doesn't appear much brighter than my (homemade) beast 25mW 635nm pointer... however it burns like a 100+ mW laser. Final picture shows it smoking some black plastic from about two feet away. Once I focus it down anything within about a meter is going to have to deal with a lot of red photons. Safety matches will go up within a few seconds and I was able to cut through a section of black electrical tape in under 5 seconds.



How else can I measure its burning prowess?

Anyway, it was a lot of work but it's immensely pleasing to see it working.

Next time i would just get the aixis module, its alot cheaper and it can focus down to more of a fine point.  Also it wont turn the diode no matter what you focus it too.

Good job with the laser its kinda like how mine looks i just soldered all the componexts and taped em together.

Be careful about that wire you soldered to the diode if it twists and the two wires touch it will kill the diode, next time i would get some non solid wire, the kind with many thin strands of wire in it and use that to solder straight to the diode since it will alow slight movement and the wire will bend instead of the diode legs bending.

for burning see if you can light fireworks thats always fun i found some with green fuses that work great, also i like to see how far it will pop a baloon, mine popped one at 25ft away.

congratulaions on your first homeade burning laser;D

p.s. dont be stupid like me and shine it back into it, i was shining at a mirror and i wondered if it would get brighter if shined it back onto itself, well needless to say it didnt get brighter , it became a really expensive led


...lazer... ;D ;D ;D

OMG! This thing burns! I now understand the appeal of high powered red lasers. I carefully adjusted the focus down to about a foot and this thing is utterly wicked. I etched the 'boo' into the side of my mouse in under 20 seconds. Smoke was just gushing. Almost like using a pen, except it etches. I knocked a hole straight through the other side of my mouse and it didn't take long. OK -- the spot is a little messy and there's a lot of scatter but this f*cker burns waaay better than my X-80 greenie. just a torch up close.

Withe the two 10 ohm resistors in parallel, the most current you can supply to the diode is 250ma's. Also you should really use 6 nimh batteries...I am sure the regulator is dropping out with four. Otherwise...you got it right..

I'm in love with this thing. I adjusted the focus so it's tightest about 1.5 feet away. Just about anything black will burn.

This is definitely NOT the last burning laser I'll be making.

For my next project I hope to get some better optics so I can get a tight focus at a distance. The single lens in my holder is OK up close, not so good at a distance.

I'll stop raving now. I've got more stuff to burn.

I have found the acrylic Meredith lens to be a great burner up close and at a distance, and it is at least equal to the Aixiz lens. Jayrob thinks the Aixiz lens is better. With all the variables involved it is hard to tell. You can also use the Aixiz lens in the Meredith module. My diode sometimes turns too..I am going to look for a solution but I think stuffing the right size o-ring around the adapter should hold it in place.

Edited..Nevermind..the o-ring idea wasn't very bright idea on my part. ;D

wooooooolazer said:

Next time i would just get the aixis module, its alot cheaper and it can focus down to more of a fine point. Also it wont turn the diode no matter what you focus it too.

Good job with the laser its kinda like how mine looks i just soldered all the componexts and taped em together.

Be careful about that wire you soldered to the diode if it twists and the two wires touch it will kill the diode, next time i would get some non solid wire, the kind with many thin strands of wire in it and use that to solder straight to the diode since it will alow slight movement and the wire will bend instead of the diode legs bending.

for burning see if you can light fireworks thats always fun i found some with green fuses that work great, also i like to see how far it will pop a baloon, mine popped one at 25ft away.

congratulaions on your first homeade burning laser;D

p.s. dont be stupid like me and shine it back into it, i was shining at a mirror and i wondered if it would get brighter if shined it back onto itself, well needless to say it didnt get brighter , it became a really expensive led


...lazer... ;D ;D ;D

Click to expand...

Hi,

Every time I focus the lens I need to watch to make certain the diode isn't rotating. Else I'll end up with the twisted legs problem you mentioned. I'm not certain why the meredith housing does this. It may have something to do with the fact the diode did not fit well into the 5->9 mm adapter thingie. Next project I'll be trying a different housing.

Hm, I'll avoid the mirror. How much scatter is normal around these Sony LD's?? Mine has some concentric circles as well as radial lines around the spot.

Gazoo said:

I have found the acrylic Meredith lens to be a great burner up close and at a distance, and it is at least equal to the Aixiz lens. Jayrob thinks the Aixiz lens is better. With all the variables involved it is hard to tell. You can also use the Aixiz lens in the Meredith module. My diode sometimes turns too..I am going to look for a solution but I think stuffing the right size o-ring around the adapter should hold it in place.

Edited..Nevermind..the o-ring idea wasn't very bright idea on my part. ;D

Click to expand...

Well, I'm using the acrylic Meredith housing, and it's not working well for me. I'm going to try a different housing for my next project (perhaps from roithner?), though I'll continue to use Daedal's circuit.

I have a couple of these and really like them:

http://www.dealextreme.com/details.dx/sku.5914

There have been problems reported with the Aizix modules.

Another option might be this modified but it will not be as easy to focus:

http://www.dealextreme.com/details.dx/sku.10095

There are lots of options...the main reason I used the Meredith module was for the cube. I do not have the tools to make my own and I needed the cube to mount my TEC to.

Its normal for the laser to have scatter around the dot, also the line going thru it is normal too, wont hurt it at all. Remember to burn best focus it to the smallest spot and youl be amazed at how good it burns.

...lazer... ;D ;D ;D

Here's a picture comparing the Sony diode (left) with my older 20-25 mW 635 nm diode (right).



The DVD burner diode appears only about twice as bright even though it's 4-8x as powerful.

The shade of red does not come through at all in the picture, the SDL diode (right) is much more orange, compared to the more pure red of the Sony (DVD) diode.

You can also see the spray and concentric circles around the spot - since this diode was never meant for use as a pointer it's not surprising I guess. There's an interesting pattern projected around the spot from the Sony diode. The spot itself sits along the edge of a circle with other concentric circles around it. The SDL diode is cleaner with less clutter around the spot.

Still I love my new pointer. It's now my brightest red, and it's a nice cherry red compared to the pink of the 635nm SDL diode. I can't put it down, lights up the room.

Projecting the spot onto the ceiling of the bathroom. It's that bright.

Eyes should be more sensitive to 635 than to 650, it's closer to the 555 peak.
Your concentric circle problems may be some transverse mode issues? :-?
Are they really big and dissapear at a distance?Cause if they're small, like a dot within a dot, that sounds like TEM 10.
Also the amount of scatter can be greatly reduced with a good clean lens.I now I used to have a beautifull spot untill I tryied various methods of cleaning my lens, now it has huge scatter and ugly lines like I see in your picture. :'( I think I scratched it.

beautiful laser! mine used to have the same artifacts around the dot, and what i hear from other laser builders like ourselves, its quite normal. well, mine USED to have those artifacts, until i killed it by discharging the cap directly into the diode :'( anyway my circuit looks very similar to yours and it used to be that big. i had it taped to a piece of 2x4 ;D although, i managed to get rid of some of the unnecessary wires and compact it into a small radioshack project box. now, the whole circuit is very compact and portable. im just waiting for my new diode to come in the mail, when i get it hooked up, ill post some pics of it. man those sony's are AWESOME!

Phew!!! Just got finished with some minor surgery on my pointer. The operation was a success.

I was having problems with the Meredith housing I'm using for the diode. The housing was meant for 9mm diodes, so I also had to order an adapter which is a small piece of brass that the tiny Sony diode gets pressed into. Unfortunately whenever I would adjust the focus the diode would rotate and squirm preventing a good focus a well as twisting the legs on the diode. Something had to be done (see this link for a picture of the meredith housing.. http://www.mi-lasers.com/cgi-bin/sh...hstart=0&template=Templates/SearchResult.html)_

I decided I was going to have to glue the diode flush against the back of the housing to prevent it from moving as well as keeping the diode in line and flush with the optical path. I did not want to do this as this would block one of the primary paths for heat to exit the diode to the case housing. Unfortunately I had no choice because I already twisted one of my soldered legs off while focusing it. I'll just have to be carefull with the duty cycle. Ideally you'd want to use some thermally conductive glue for something like this, like arctic silver.

So I glued the diode flush and centered, and I also decided not to attempt to solder any more wires to the diode legs. Too sketchy. Instead I carefully attached two alligator clips directly to the diode legs.

Here's a new picture of the innards:


Now the diode stays put while I focus the lens AND I'm now getting a very tight spot at focus!! The concentric circles I had seen earlier around the diode spot are now gone. They were probably caused by the fact the diode was not centered in the optical path.

It's over kids, this thing burns. It will pop UNSHARPIED blue balloons out to at least 15 feet with the focus set to infinity. It will pop sharpied balloons out the limit of my apartment range (20-25 feet) though it can take up to 10 seconds. Up close it's mean. I love it.

I've decided for my next laser I'm going to house it in this meredith block. Just glue it into place and focus the lens from the front.

That looks bad, you should never use aligator clips, if they come uncliped while its on and make contanct back to it, even if it is a nanosecond, the cap will charge to 6v from the regulator not having a load on it then when it makes contact it will discharge that nice jolt to the diode

I would still solder some wire to the diodes leg, just tape them each individualy with electrical tape so they wont be able to touch, it would be alot safer.

...lazer... ;D ;D ;D