Did I fry my LD?

[waro]

My first laser build (my only other laser experience is my laser gun sight) so please be gentle. I am trying to make an Arduino controlled wood burner.
I reclaimed a 650 red LD from a 16x DVD burner. In my lack of patience for items to arrive in the mail...I hooked up the LD to my ATX bench PSU at 3v--(yes I did not wait for my driver to arrive and just hooked it up directly to the PSU). Initially I hooked it up just to see if it was still a good LD...but then I got bit by the laser bug and started to play with it more and more. So far it has been connected less than 50 times for a total time of less than 10 minutes. It is mounted in a heat sink like the one below. The longest it was run was about 5 minutes and got warm to the touch but thats it. It is still very bright and the beam is focused to a dot about .125" at 6". It will not how ever burn or melt anything. At 2" it would not light a black match.

My plan was to learn more and get used to lasers and then if this "works" and I dont blind myself... I could upgrade it to a 2w blue burner. The LD was salvaged from a burner pulled from the trash...so I am not too worried about it but I will need to try to wait for the driver to come. I was also thinking maybe the lens/housing are crap and that is part of the problem.



1pc 5 6mm T018 Industrial Laser Diode House Housing Lens 18x45mm Case | eBay

 

[upaa27]

My first laser build (my only other laser experience is my laser gun sight) so please be gentle. I am trying to make an Arduino controlled wood burner.
I reclaimed a 650 red LD from a 16x DVD burner. In my lack of patience for items to arrive in the mail...I hooked up the LD to my ATX bench PSU at 3v--(yes I did not wait for my driver to arrive and just hooked it up directly to the PSU). Initially I hooked it up just to see if it was still a good LD...but then I got bit by the laser bug and started to play with it more and more. So far it has been connected less than 50 times for a total time of less than 10 minutes. It is mounted in a heat sink like the one below. The longest it was run was about 5 minutes and got warm to the touch but thats it. It is still very bright and the beam is focused to a dot about .125" at 6". It will not how ever burn or melt anything. At 2" it would not light a black match.

My plan was to learn more and get used to lasers and then if this "works" and I dont blind myself... I could upgrade it to a 2w blue burner. The LD was salvaged from a burner pulled from the trash...so I am not too worried about it but I will need to try to wait for the driver to come. I was also thinking maybe the lens/housing are crap and that is part of the problem.



1pc 5 6mm T018 Industrial Laser Diode House Housing Lens 18x45mm Case | eBay

What current was going into the ld?

 

[waro]

No clue. It was just hooked directly to the PSU....so basically I am thinking too much, but have no ideas about actual current.

 

[ARG]

IIRC those LD's have a forward voltage around 2V. At 3V you delivered way to much current to the diode.

LD's should be current driven, not voltage driven.

Hooking an LD up to a voltage source will almost always kill it.

 

[waro]

When I had researched it before I thought it looked like they were 3v (2.7-3.3v) diodes and that is why I figured it was ok to try it quick...the problem was I could not put it down
I know I have to force myself to keep my hands off of it until I get the rest of my parts...to bad they are fun to play with. I do have another burner that I could tear a part..but that burner is not in the trash yet I dont want to break it down yet. Hopefully I get the rest of my stuff soon and I can start to really play, but I did not want to spend a lot of time trying to burn stuff if it is not going to happen.

 

[DTR]

When I had researched it before I thought it looked like they were 3v (2.7-3.3v) diodes.

That forward voltage range(if it is right seems a bit high for a 660nm diode) is the reason they need to be current driven. Depending on temperature the diodes voltage draw will change due to changing resistance in the diode. If given a fixed voltage as the diode heats up it draw more current causing more heat causing more current in a cycle till it dies this is called thermal runaway. When using constant current to power the diode as it heats up the voltage draw drops which is not a problem and the diode stays in check.

 

[The Lightning Stalker]

Hello, Mr. waro and welcome to the forums.
A 2W diode will be a vast improvement for
CNC would engraving. I wood recommend the
M140. They are a very serious eye hazard,
though and you should purchase good safety
glasses first. We usually get them from
Survival Laser or AixiZ. Be sure they
match the wavelength of your diode. Also
beware of cheap eBay glasses (and
prettymuch anywhere else selling them for
such a low price) and avoid them like the
plague. This is a case of, "You get what
you pay for."

You should also have a fan set up to
extract the smoke and keep it away from the
optics. It can also double as a cooling
fan for the laser module, or you can use
another fan. Even with a fan or fans, you
may need additional heatsinking for that
type of module. An M140 can get hot fairly
quickly. An appropriately sized aluminum
shaft support attached to a finned heatsink
will help quite a bit.

2X SK20 Size 20mm CNC Linear Rail Shaft Guide Support FKS | eBay