Completely homebrew burning laser.

[psych787]

Some background on the DVD burner (skip on if you want, just note I don't want to open it up until I'm sure this project has a good chance):
A few months ago, I bought an OQO on ebay. Of course the stock unmodified WinXP Home sucked for performance, and a USB DVD burner was quickly obtained to install a customized OS which ran far better. Importantly, windows identified a USB to IDE adapter on the drive. Two months later my PC fried after 6 years of use. Deciding it was cheaper and better to move from PATA to SATA, I successfully used it to copy and wipe my old PATA disks. Now I have two IDE DVD burners - one in the PC and the other in the original casing with its USB to IDE connector. Obviously destroying the second drive means I would have to remove my PC's DVD drive whenever the OQO needs to be rescued.

Having seen the awesome videos out there, I'd love to make a "burning" laser. It would be even better to prove that it can be done with nothing but the DVD drive.

I see several problems with this:
1) Diode laser output is not colliminated. Can the DVD lens be used for this purpose? The optics simulation page seems to indicate that any convex lens should work.
2) Can the built in heatsink be used, or a heatsink be improvised with solder or similar material?
3) What's the simplest driver possible? Would a capactior and resistor be enough? I don't want to kill the diode on first use, but parts should come strictly from the DVD burner.
4) Can the laser diode be fed extremely low power to work out the optics over a long period of time?

 

[styropyro]

For 1 and 2, Get one of these, it has a built in adjustable focus lens, and it heatsinks the laser diode.
3. Technically, you could use just a resistor and a capacitor, but as the batteries died, so would the power of your laser. I really suggest either building a DDL driver or buy some of the drivers in the Group Buys here.
4. You can feed the laser lower power, but I don't see why you would want to do that, just leave the diode at full power and focus the lens on the aixiz module for either burning or for a dot at a ong distance.

 

[laserwayne]

i know that if you don't use a driver it will burn out very quickly but will it work at all? just so everyone knows i have waited 15 days for my laser from dx and 5 days ago i got an email that said it was back ordered and was coming in 4 days. i waited anxiously to discover on the 4th day it was shipped from hong kong yesterday. if your going to reply please post the awnser to my question also

 

[chido]

If you mean when you connect a diode straight up to two AA batteries, it depends on the diode, some might die the moment you connect them straight up to the batteries, others might work but not for long, and others might last for months. ;D

 

[cbrian4]

I suggest that if you don't want to build a driver, that you find a flashlight with a driver already inside like an LED flashlight and install the diode (mounted in an aixiz module) into that. Then you can just add any sort of resistor to the diode to limit the current. I would not recommend that you just hook up the diode straight to the batteries, if your really going to tear up a burner and go through all the hard work of extracting the diode, wouldn't you want something to last you more than a few minutes?

 

[psych787]

Thanks for the replies.

When the batteries start going bad, I'll replace them. I don't plan on running this for minutes at time or anything. The reason for running it at low power is to run it for long periods of time without risking heat damage or anything.

I am aware of the many colliminated lenses out there. I would prefer not to buy one, but to use existing materials. Has anyone tried using the lens from the DVD burner?

 

[Switch]

I have tried all the lenses I could find in the sled and can safely say they all SUCK for collimation At best you're gonna have a laser with a lot of divergence.And if you don't plan on using a proper driver you use NiMH cells.Their lower voltage makes'em somewhat safer.

 

[psych787]

Ouch. So 100% DIY is not going to work. Thanks for the tip on NiMH batteries anyway... I'll just have to get myself a cheap laser pointer or lens someday.

Something else I've been wondering... if you have to collimate the laser, then what's the point of using a laser instead of a high-power LED?

 

[BlueFusion]

Because a laser is at least somewhat directional to start with. And most importantly it's coherent.
http://en.wikipedia.org/wiki/Coherence_(physics)
That's what makes a laser special. An LED even with a LOT of lenses is not gonna be nearly as directional.

 

[psych787]

To make a better example, let's say you're running a milling machine. Why not use colliminated light? You could pick up 10kw monochromatic lights a lot easier than lasers. Are interference losses really that imporatant?

Understandably a laser diode produces "cleaner" output than an LED, I was just wondering if that was the only reason for using one.