DIY Laser won't burn anything

[tobivan]

Hello,
I have built a DIY Laser engraver according to this tutorial:
fun of DIY: A Raspberry Pi controlled mini CNC Laser engraver [last update Jan 18,2014]

I bought this laserdiode:
Sony RLD65PZB5 658nm Laserdiode 80mw/240mw - Insaneware Deluxe

According to the specs it can supply ~120 mW CW at a voltage of 2.5 V.

I am using the LM317 according to the tutorial mentioned above and I can measure 2.0-2.7 Volt and a current of between 100 and 190 mA. So I assume the circuit is working fine.

The laserdiode is in an Aixiz-housing, produces a nice red dot and is getting warm after a minute or so. BUT it looks like a very weak laserpointer-dot and it doesn't burn anything, no matter how far/near or focussed, black or white surfaces and so on. It seems to me as if the laserdiode produces heat and no "optical power". A second diode, identical, has the same results.

Thank you very much for helping me.

 

[Aleksa]

The diode is dead. Give us a picture to confirm. Diodes are very sensitive.
And what schematic did you use ? Better build a constant current regulator with a mosfet and an op amp then the crappy lm317.

Edit: I see the schematic now. It's unstable and just not a good idea. Use this :

http://rommet.com/remco/misc/Don's Lights/members.misty.com/don/glpdrv3.gif

 

[tobivan]

I edited my first post the other minute, sorry. I have a second, identical laserdiode with the same results.
The schematic I used is the one with +9V supply:
http://1.bp.blogspot.com/-ewI7TGlE0q8/UmvuF9vmrSI/AAAAAAAABrM/pn0yN2P9Vpo/s1600/laser_driver.png

Do you have a link/source for a "better" constant current regulator with a mosfet?

How can one see from a picture if the diode is dead or not? I'll try to take a picture ;-)

 

[Aleksa]

When a LD dies it becomes more like a LED. It produces a weary dim light that looks nothing like laser beam.

 

[tobivan]

I see. Well, the beam definitely looks like a laser beam, but a very dim one. It reaches about 50 cm. The diode itself looks "unharmed" from the outside.

 

[Aleksa]

Still waiting for the picture

 

[tobivan]

Sorry:
1st one focussed
2nd one "not very focussed"
distance laserdiode-paper roughly 5 cm
http://www.imgbox.de/show/img/WV3I2b9cd9.jpg

http://www.imgbox.de/show/img/B5HLvyl2kg.jpg

EDIT: I used the embed IMG tag, but the pictures won't show up, so sorry about the link.

 

[Aleksa]

That's exactly what i'm talking about. That is a dead diode. Your driver has killed them.

 

[tobivan]

Interesting, how do you see that? I mean, the dot looks "small" to me.
But nevertheless I suppose you are right, because otherwise something would happen.
In your schematic: what is "U1 B14" and "Q1 617"? I can't find them.
Thank you very much!

 

[Aleksa]

If this is your first laser,you will see the difference when you get the new one working.
I dont need to mention that you need to be careful with the laser? If the laser hits your eyes...you will get blinded. Eye protection is needed.
For the driver, i hope you have some good experience with basic electronics,if not,EEVblog on YT is the way to go. When you learn the basics,go to Sams Laser FAQ (holy grail of laser knowledge).
I gave you a simple schematic just so you can see what kind of driver you need. Dont use BJT,use a mosfet instead. For the OP amp,use a lm358.
Have in mind that this is not an efficient way to drive anything. If the diode is working on 2.5v and you have 5v as a supply,2.5v will bi dissipated in the mosfet as heat. Basic learning will cover that.

 

[tobivan]

Thanks Aleksa. I am familiar with electronics, but not with driving a laser diode. As quite a lot of people seem to be happy using a LM317 as constant current source I thought there shouldn't be so much of a problem. I double checked my circuit and could not find any errors in assembly. I am still puzzled and now wondering a) where to buy a new diode b) how to solder a WontKillLaserAgain-driver

Thanks again!

 

[Aleksa]

Start basic,take it slow,go easy.
You cant run if you cant walk.
Without knowledge time is wasted.
This forum is best on internet,all the information needed to start is here.
There is a search bar on the bottom of the page,have a try at it.
If you need any help,you can always ask and you will get it.
Stay safe and have fun :beer:

 

[dragonsking]

Hello. I am a newbie on this and i would like to share with you what I see, maybe you cna help me. My laser doesnt engave anything, just the light (a very strong one) but nothing engraved. I unplug one of the cables on the head of the laser by mistake and when the laser turns on, the beam makes a hole on the surface. So it have power, but when the cables are on the head, they engrave nothing. any idea?
BIG THANKS

 

[Cyparagon]

So that's clearly a problem with your ENABLE signal. Find out why there's no ENABLE. Either you fucked up the software settings, or your signal driver died. I'm betting on the former.

 

[dragonsking]

So that's clearly a problem with your ENABLE signal. Find out why there's no ENABLE. Either you fucked up the software settings, or your signal driver died. I'm betting on the former.

I import some setting from a supplier and now the laser engraves from time to time... but always with the x axis disaligned