Salvaged a laser from a DVD

[n2ize]

I just got done salvaging a laser diode from a 16x DVD RW. It emits light in the red spectrum. With an appropriate driver, housing, and focusing lens it will make for a nice laser module for experiments with enough power to heat, melt, cut, or burn llghter materials. I'd eventually like to salvage a laser module from a Blu-ray drive but so far I don't have any crapped out Blu-Ray drives on hand.

Nice part is that when many of these optical drives fail in a computer the laser is still good.

Of course all the above is done while wearing proper eye protection.

[ki4itv]

I'll lend you one of my hammers if you're in a hurry for that part from the Blu-ray device.;)

[KG4CGC]

Hey John! Change your password! Your account has been hijacked!

Hello?

[N2CHX]

Hey John! Change your password! Your account has been hijacked!

Hello?

Ha! I was just thinking that. Where is Tootie Frooty Rudy Patootie these days? I haven't seen him post in ages. Is he in jail again?

[KC2UGV]

Ha! I was just thinking that. Where is Tootie Frooty Rudy Patootie these days? I haven't seen him post in ages. Is he in jail again?

He got the banhammer.

[n2ize]

Ha! I was just thinking that. Where is Tootie Frooty Rudy Patootie these days? I haven't seen him post in ages. Is he in jail again?

He was banned for making some callous remarks among other things. As far as the laser experimentation goes, there are many of us and I used to wonder about some of Rudy's claims. In any even you can harvest some nice laser components from todays DVD and Blu Ray drives.

[kb2vxa]

I doubt an LED laser or otherwise can generate much if any noticeable heat, you need a few watts from a He/Ne laser at close range to do that. You can perform some heat experiments though, I had a lot of fun playing around with a modulated IR diode and photocell transceiver with another similarly equipped ham down the street at an old QTH.

"Where is Tootie Frooty Rudy Patootie these days?"
Over at http://www.radioreference.com/forums/

"Is he in jail again?"
More or less, they don't allow nearly as much freedom of speech over there so he's been behaving himself... so far.

[n2ize]

I doubt an LED laser or otherwise can generate much if any noticeable heat, you need a few watts from a He/Ne laser at close range to do that.

A low power laser diode won't generate much heat. But I have seen higher powered red laser diodes in the 150-350 mW range that will generate enough heat to easily burn or ignite objects placed in the beam. I have experimented with a 532nm diode pumped solid state laser in the 150 - 200 mW range that will burn dark colored plastic or paper objects held in the beam and/or ignite matches held in the beam within a second or two. Of course to accomplish this the beam has to be focused within relatively short distance of the laser, anywhere from a few inches to maybe a foot away from the laser aperture. You can get this kind of power from red laser diodes harvested from old DVD burners and violet/blue diodes harvested from Blu Ray drives. Of course proper laser eye protection specific for the wavelength being used is mandatory at all times as well as a practical knowledge of laser safety laws. And always observe that warning sign..."Do Not Stare into Laser Beam with Remaining Eye" ;


You can perform some heat experiments though, I had a lot of fun playing around with a modulated IR diode and photocell transceiver with another similarly equipped ham down the street at an old QTH.

The nice thing about laser communications experiments is that you don't need much power at all. Low power IR and Red diodes of 1 - 5 mW are more than adequate for significant range and the low power diodes are quite cheap. I've seen them for less than a buck in some places as well as ready made low power modules i,.e. diode + collimating lens for as low as $3.00 - $5.00. Just hook em up to your power supply/modulator any your good to go.

"Where is Tootie Frooty Rudy Patootie these days?"
Over at http://www.radioreference.com/forums/

"Is he in jail again?"
More or less, they don't allow nearly as much freedom of speech over there so he's been behaving himself... so far.[/QUOTE]

[KG4CGC]

Well have fun. That's what it's all about.
And be careful with that thing. You'll put your eye out kid!

[KC2UGV]

I've got a couple DVD players waiting to be scrapped. What kind of lens should I use if I want to build a make-shift optoisolator? Or, will I need any kind of lens?

[W1GUH]

Well have fun. That's what it's all about.
And be careful with that thing. You'll put your eye out kid!

Why I don't play with lasers. There's a more fun way to go blind (still waitin', tho).

[NQ6U]

Why I don't play with lasers. There's a more fun way to go blind (still waitin', tho).

Sort of like all those acid flashbacks they warned us about. Still waitin'

[W1GUH]

Yea, but you got Bigfoot to keep you company. Wish I did.

[n2ize]

I've got a couple DVD players waiting to be scrapped. What kind of lens should I use if I want to build a make-shift optoisolator? Or, will I need any kind of lens?

I doubt you would need a laser diode to construct an optocoupler...unless the coupler is being designed to huge with a long distance between components. Otherwise a standard regular LED should work. I think most commercial optocouplers use an infrared LED + IR photo transistor. For the lens I guess you could use a small convex lens with a very short focal length to focus the light onto the substrate. Or, you may want to diverge the light over the entire area of the substrate. However, I am thinking that if the device is small you may not need a lens... component proximity alone should be enough.

Is there a particular reason you would build your own ?? Couldn't you simply purchase a commercial optocoupler chip ?

One quick and dirty homemade optocoupler consists of a small length of heat shrink tubing with an LED at one end and a phototransistor on the other. The diagram shows no lens used at all.

[KC2UGV]

I doubt you would need a laser diode to construct an optocoupler...unless the coupler is being designed to huge with a long distance between components. Otherwise a standard regular LED should work. I think most commercial optocouplers use an infrared LED + IR photo transistor. For the lens I guess you could use a small convex lens with a very short focal length to focus the light onto the substrate. Or, you may want to diverge the light over the entire area of the substrate. However, I am thinking that if the device is small you may not need a lens... component proximity alone should be enough.

Is there a particular reason you would build your own ?? Couldn't you simply purchase a commercial optocoupler chip ?


Why buy, when one can build from freely available parts :)



One quick and dirty homemade optocoupler consists of a small length of heat shrink tubing with an LED at one end and a phototransistor on the other. The diagram shows no lens used at all.

Are laser diodes coherent at all without the lens?

[NQ6U]

Are laser diodes coherent at all without the lens?

All I can say about coherency is that I can never understand what they're saying...

(Seriously: Yes. Laser light is coherent by definition.)

[n2ize]

Why buy, when one can build from freely available parts :)


True.



Are laser diodes coherent at all without the lens?

Yes, the light is by its nature is coherent in that the monochromatic light waves are all in phase However there are different "types" of coherency, i.e. temporal, spatial, etc.

Incidentally, men created coherent light even before the laser was invented. It was done by filtering to produce extremely narrow (monochromatic) band of light from a discharge tube and then doing some further filtering..the nature of which I forget. I believe there are also other ways to produce coherency without a laser.

As far as the light from a laser diode, yes it's coherent light but it diverges as it emanates from the diode. To produce a nice narrow beam you need to use a collimating lens. For about 2 or three bucks you can get a module + lens. You press the diode into the module, attach the lens connect it to a driver circuit and you've got a laser that will give a nice narrow long range beam. Also, be careful. Laser diodes are easily damaged by dust, static, reverse polarity, voltage spikes, etc.Another source of a collimating lens is by hacking a cheap 2 dollar laser pointer. But often they are difficult to disassemble.


Disclaimer!! Just a word of caution, if you ever do decide to hack and salvage a red laser diode from a high speed DVD burner or a blue laser diode from a Blu-Ray burner be careful to wear laser safety goggles for the specific wavelength you will be using. Many of these diodes are Class IIIb and are capable of putting out >100 mW of power. At those power levels if the beam or a direct reflection of the beam hits the eyes it can burn/damage the retina of the eye in 1/100th of a second !!. That is faster than the blink reflex. Also, never point them outside at windows, people, vehicles or aircraft. It is a now a federal offense to point a laser at an aircraft.

[n2ize]

Latest update... I drilled out a piece of brass tubing to act as a holder for the diode and I ordered a collimating lens. I am going to mount the whole assembly i.e. diode, holder, lens in a heat sink from an old computer. it will be powered off a computer power supply, via an LM-317 VR which will act as the heart of the driver circuit for the diode.although i could use batteries. I estimate that at a current of 250-320 mA the diode should put out about 250-300 mW of red laser light. I'll try and post some pics when its all finished.

Future upcoming projects in this realm will be the construction of a working TEA laser. Noiw that will be a true scratch build. :)

[KG4CGC]

Be careful not to burn down New York.

[NQ6U]

Be careful not to burn down New York.

Also to keep the thing out of the hands of al Qaeda/the Taliban/Gaddafi/the terrorist threat of the week.

[n2ize]

Also to keep the thing out of the hands of al Qaeda/the Taliban/Gaddafi/the terrorist threat of the week.

And most important... Keep it out of the hands of Rudy. Could you imagine if he hooked it up to his APU ??

[KG4CGC]

And most important... Keep it out of the hands of Rudy. Could you imagine if he hooked it up to his APU ??
His APU? What about yours?

[NQ6U]

And most important... Keep it out of the hands of Rudy. Could you imagine if he hooked it up to his APU ??It would mean The End of the World as We Know It.

[n2ize]

I tested out the diode today using a crude collimating lens, two 3.6 Volt lithium batteries as the power source, a magnifying glass as the focusing lens. I JS'ed the thing together using some breadboard and a pair of "helping hands" to keep the laser diode and lenses in place. I limited the current to around 220-250 mA and applied power to the diode. It gave me a beautiful beam of nice rich red laser light. By moving the magnifying glass I adjusted the focal length to roughly 1 - 2 feet ahead of the laser (i.e. the point in which a piece of black paper held in the beam started to smoke. A match held in the beam ignited in a second and it had no trouble burning a clean hole through a black CD case. At that point I shut the diode down so as not to overheat and damage it. All in all its pretty impressive. Plenty of power considering that I was running it conservatively as around 220 mA. With proper heat sinking and bettter regulation I can probably run it well over 300 mA and it will deliver considerably more power. Now all that remains to do is to mount the diode in a better module with better collimating and focusing lens, mount the assembly on a heat sink (salvaged from a computer) and build an enclosure and I'll have a handy "lab laser" for experimenting which can be run off batteries, a computer power supply, plugged into a USB port, etc. This is essentially a laser built almost entirely from junked computer components.

P.S. Of course I wore laser safety goggles when testing this device. Better than risking blindness.