650nm 300mw Laser Module Lasing but no longer burning

[DaxMoonJuice]

Hi Guys

I recently bought a red 300mw diode module from OdicForce
Component Bundle for 650nm (Red) 300mW+ Laser Module in Chrome Case (External Driver + Glass Lens) - OdicForce.

The module was powered of a 13.7v supply from a power supply which uses a LM317 chip to regulate voltage off a laptop power supply brick. The diode did burn things whilst drawing current from this supply


It was powered through a LM358N op-amp driver circuit which pulled about 450ma and fed around 420ma of this to the diode itself.

I had some success burning materials until this weekend, when I noticed that the diode would blink on an off (several second apart). I belive this was due to a heat issue with the tiny surface mount mofset the driver module used. My suspicions where confirmed when stability improved after the addition of a heatsink on the driver board.

However now the diode does not burn any of the items it once did. I can still focus the beam as tightly as I did before and according to current readings in line with Diode+ and Driver Out + it still draws 400+ma of current. I have also noticed that the diode produces less light "splash" than it did before. When it worked the bottom of my goggles where bathed in a red light whereas now that waste light is now dim/non-existant.

I have tested the diode using the driver provided by Odic Force and a homemade LM317 constant current circuit which delivered 500ma of current at 13.7v and around 400ma at 7.5 v(a bit high but still within the tolerances of the diode (LPC-826 658nm Red Laser Diode 250mW+ CW - OdicForce).

LM317 circuit

LM317 Current Calculator - Electric Circuit

OpAmp driver circuit

High Current LM358 Laser Diode Driver (405nm / 445nm / 635nm / 650nm / IR Diodes) - OdicForce

But neither setup lead to the desired burning.

It doesnt look like the diode has LED'ED. I have broken red diodes before and the beam they produce (even after being focused through a lens) is not as intense as my diode.But I could be wrong.

Could it be a dirty lens? My finger have pressed against the lens several times before


Here are some pictures of the beam

Here is the focused beam

https://drive.google.com/file/d/0B8pvPiWhMwS9M3NXR0E3MEttbFU/view?usp=sharing

Here is the unfocused beam for comparison
https://drive.google.com/file/d/0B8pvPiWhMwS9bFdwT2ZZR1ktVWc/view?usp=sharing

Help me laserpointerform your my only hope! =P

 

[diachi]

Looks to me like it LED'd - or at least nearly LED'd. If it's still eating up ~400mA and that's all your getting out.

 

[DaxMoonJuice]

Interesing, thanks diachi. So there are degrees of LED'edness?

Any idea what might have caused the failure?

Its been soldered or bread-boarded to a driver since I had it. I'm not sure if Static is to blame.

Do you think the diode could have got too hot?

It was running within the module specs and even then, for a short amount of time, like 1-2 mins.

 

[diachi]

Interesing, thanks diachi. So there are degrees of LED'edness?

Any idea what might have caused the failure?

Its been soldered or bread-boarded to a driver since I had it. I'm not sure if Static is to blame.

Do you think the diode could have got too hot?

It was running within the module specs and even then, for a short amount of time, like 1-2 mins.

Heat is the most likely culprit - looks like you don't have it in a heatsink. A heatsink is most definitely recommended for a red at those powers.

Could be static or too much current as well but that's less likely.

 

[DaxMoonJuice]

Cool thanks for the advice.

Any idea what sort of characteristics the heat sink would need?

I was thinking about using this one

https://goo.gl/9hkF8o

 

[diachi]

Cool thanks for the advice.

Any idea what sort of characteristics the heat sink would need?

I was thinking about using this one

https://goo.gl/9hkF8o

Yep, that should do a decent job - especially if you can bolt that onto something else which is metal.

 

[DaxMoonJuice]

Awesome thanks for the help!