Laser diode (burning laser diode type) help

[luka_friend]

Hi everyone!
I don't have a lot of electrical knowledge, so I will try to explain my problem the best as I can.
I have a MITSUBISHI/658nm-660nm 300-400mw CW Red Laser Diode, and 5.1V 0.7mA power source (used for charging mobile phones).

My 1st question is:
-if one pin on laser diode is positive and one pin negative power, what is the third pin?

And my 2nd question is (also my problem):
-I have wired a few resistors to drop the voltage of power source to 2.2V (which is specified for laser diode). When I plugged the laser diode to power source, I could see a little red dot, but not even close for what I need for laser cutting. So what am I doing wrong (I have seen tutorials on web using the same laser, so I think laser is not the problem).
-Should I connect both laser diode pins to + and the third pin to -?
-Should I use diffrent power source (some kind of switching power supply)?


Laser diode is from ebay: **broken link removed**
Laser diode would be used for cutting paper.

Thanks.

 

[tggzzz]

Be aware that your eyesight is in danger. That doesn't bother me, since your blinding yourself would be another example of "evolution in action".

What would make me extremely annoyed is if you blinded an innocent bystander, or somebody just wandering around. If I was that innocent third party, I would do all in my power to ensure you could not pass your genes on to the next generation. Seriously, no joke.

It takes remarkable little power for a very short time to irreversible blind someone. Even if 99% of the power missed the eye, the eye could well be blinded. How much would be reflected off of a mirror or metal surface?

There's a motto amongst those working with lasers: "do not look into laser with your remaining eye".

 

[Audioguru]

You bought a laser diode from ebay who knows nothing about its 3 pins. Maybe ebay printed its part number wrong because www.datasheetarchive.com never heard of it.
Google Images shows what the 3 pins are for, one is not used.
You forgot to say the resistance of the resistors you tried so maybe you burnt out the laser diode, or reduced the current too low. A resistor in series limits the current and has nothing to do with the voltage that the laser diode uses.
The resistor is in series with the laser diode which is 2.2V so the resistor has 5.1V - 2.2V= 2.9V across it. Then for a current of 300mA Ohm's Law calculates the resistor value to be 2.9V/300mA= 9.7 ohms. Use 10 ohms/2W. Don't burn yours or somebody else's eyes out.

You said your charger is 5.1V/0.7mA which is almost no current. It is probably 5.1V/0.7A instead.

 

[tggzzz]

Don't burn yours or somebody else's eyes out.

Let's hope the OP takes note of >1 person telling them that.

One alternative, inspired by RAF pilots during the cold war, would be to wear an eyepatch. Then they could still use their remaining eye.

 

[FvM]

I basically support the warnings by tggzzz.

Regarding technical details, even the scarce Ebay offer has more information than the OP got, e.g. a clear pinout picture.

The LD is specified with 400 mW pulse power, with some effort you are able to locate a manufacturer datasheet of either the original or a similar part.

I don't believe that the power is sufficient to cut paper, at least not without optics.

 

[Audioguru]

The ebay thumbnail photo of the pins is so faint that I didn't notice it.

 

[Dan Mills]

You typically need a proper current source for running laser diodes (The difference between threshold current and burning the facia (thus turning the thing into an expensive LED) is often small and damage happens in well under a microsecond.

Laser diodes are all kinds of static sensitive in general which does not help.

Now that diode is advertised as pulsed, which can mean several different things, none of them good for your application.

I would suggest a wander over to the photonlexicon forum where lasers are the whole topic and where some real laser professionals hang out.

Regards, Dan.

 

[luka_friend]

I'm sorry it took so long to reply, but I was really busy.

First reply is to Audioguru - yes, current for my power source is 0.7A not 0.7mA (sorry my mistake), and I will try again and post how much current goes through laser diode (with multimeter).

Second is to tggzzz - Yes I am well aware of the danger laser can do, so I work in my garage (alone with my protective glasses) and I have never pointed laser to human being ("I would do all in my power to ensure you could not pass your genes on to the next generation" <- seriously - I am not going to comment that)

To FvM - I have a small laser diode module that comes with glass lense

And to Dan Mills - ok, thanks for info, I will try on photonlexicon too.



What I am trying to build is laser cutter by the help of the posts I have found on the web. I have used the same laser and the same laser module as on the first link, but not the same power supply regulator (on the first link is used **broken link removed**). I thought I could used mobile charger and reduce the voltage to proper laser voltage demand. So my problem is more about power supply than laser diode. Is it maybe because switching regulator works diffrently?

LINKS:
http://der-frickler.net/technik/lasergravierer
http://jenslabs.com/2013/12/16/what-can-you-cut-with-a-300mw-diy-laser-cutter/
http://hardwarebreakout.com/2013/03/diy-laser-cutter-for-pcb-stencils/

Thank you all for your responses and I apologize if there is something I am doing wrong, I am just a rookie.

 

[ArticCynda]

Return the diode under Ebay's buyer protection and get your money back. If you don't know how to wire up a dangerous component like this, you shouldn't be playing around with it. Start with a harmless red LED to learn the basics.

 

[tggzzz]

Return the diode under Ebay's buyer protection and get your money back. If you don't know how to wire up a dangerous component like this, you shouldn't be playing around with it. Start with a harmless red LED to learn the basics.

That's sensible advice, on both counts. I hope the OP takes note.