First Laser, have a few questions.

[Tanky321]

I'm just getting into this laser stuff, and man is it a good time! I just picked up an A140 diode, Aixiz 12X30mm module and a glass lens. I machined a housing/heatsink for it and did a little testing today. I drove it at about 1.25A, with a lab supply.

Now here are my questions....

1.) Ultimately I want to use this to burn wood designs, via CNC. I know its going to be slow, but being new to lasers, I would like to start slow. That being said, is there any advantage to run the laser via PWM for this application? PWM frequency would be roughly 15kHz.

2.) I had read that there is no advantage to running the LD over 2A, but Im not sure if that is continuous or PWM?

3.) What is a safe forward current assuming no TEC cooling, only my heatsink shown below?

Thanks!

Andrew

 

[TheDukeAnumber1]

Those are great questions, I personally don't have any answers for you but I'm glad you asked them. Welcome to LPF! :yh: and nice looking heat sink btw.

 

[Tanky321]

Thanks! Its just something quick and dirty that I made up to test with.

 

[Tanky321]

I had an interesting problem today, I think the LD may be on its way out... :cryyy:

I ran the LD yesterday numerous times, no longer than 3-5 minutes each time. It worked beautifully every time, I was able to burn through yellow post it notes, blue tape, and black plastic with no problem. I was also able to burn wood easily.

Well, today I went to power it up and it seems that the output power has dropped! I have a hard time burning through the post it notes, and in general it burns everything at a much slower rate. Also, I noticed that the heatsink seemed to get much warmer today than it did yesterday.

Its an A140 diode, my current yesturday ranged from 800mA to about 1500mA. Did I go overboard?

EDIT: From doing a little more research it appears that I did go overboard... Oh well, live and learn!

Thanks!

 

[Fiddy]

your duty cycle may be your killer not the current.

 

[TheDukeAnumber1]

your duty cycle may be your killer not the current.

I would agree with that, your heat sink is pretty good but 5min is a really long with with passive cooling.

 

[grainde]

Just a question did you check the focus? If it has moved, it will affect how well you can burn.

Also you might be better off with an M140, or maybe even a new 9mm 445, as these can take higher currents ie 1.8 and ~2A respectively. DTR sells them if you're interested and he even has copper modules for them...In your picture it looks like you are using an aixiz module, which is brass, and not as good as copper for removing the heat generated.

Welcome :beer:

Edit: Nice heatsink btw!

 

[Tanky321]

Thanks guys, I ordered an M140 last night.

Assuming passive cooling, what is the max current and duty cycle these should be run at?

Ive got some peltiers, so I may try to actively cool this as well.

 

[grainde]

Generally max 1.8 A for an M140 and duty cycle depends on heatsink. Most people run the M140's in handhelds for 1 - 2 mins max, but that again depends on the heatsink! My C6 I keep below 1 min and my Saik can run for 3 + mins, but I still stick to around 1 min. If you have active cooling that of course would be better and you can get much longer run times. Dont forget copper.... :beer: