Bad Luck Laser

[Zom-B]

It seems my semi-ghetto peltier-cooled handheld lab device has been nothing but bad luck.

Bad luck lens (getting refunded because of optical aberrations)

Bad luck switch

Bad luck batteries (they discharge in 30 seconds and get quite warm, because I overloaded them 2.3 times over: 3.1A where max is 1.35A.)

Bad luck driver

And finally... Bad luck diode

When I was graphing it, and hit 1700mA, the dot suddenly started to dim, I immediately disconnected it which was within a fraction of a second. Then I tapped the contact intermittently, and nonetheless the amount of lasing kept getting less, and after 2 seconds or so of on-time it hit what looks like COD.

The laser was getting quite hot, because I worked the peltier sub-optimally to prevent it from freezing in between measurements, but it wasn't too hot to hold. (It has been hotter in the past.) My guess is that at 1.7A it just reached the end of it's life (which was within 5 minutes in total).

At least the laser diode left a legacy:

Extra keywords: M140 M-140 power graph chart

 

[Leodahsan]

Something isn't right.
I read "peltier cooled handheld",
Then I see 14500 batteries
Then I read 1.7A current.
60W thermoelectric coolers can (and will) draw >2A from a single li-ion. 5A If 3 li-ions, series.

I don't think it is bad luck, maybe bad planning? :thinking:
I don't see any links to a build thread or anything
and what the caps on everything, related to??

Not mean't to bash or anything.

 

[Pi R Squared]

Sorry for your loss but at least its some experience, you will do better next time. Yes certainly too small of batteries you needed something much larger. Did you really test that with an acrylic lens up to almost 1200mw? I would think it would be smoking about then. Good luck with your next build.

 

[Zom-B]

@Leodahsan the link is right in the first sentence. links don't automatically underscore for some reason. The peltier has it's own linear driver. And it's nowhere near 60W.

@Pi×R² that's why I was changing batteries to something beefier. I have experience enough. I graphed dozens of PHR-803Ts and some reds, and of course sometimes they die, but this wasn't over-driving compared to before.

I was surprised how well the acrylic held out. After I put it in, I unfocussed it so I could inspect the beam pattern and see any signs of melting or deforming, then powered it at full power for about a minute (no driver, because it broked, but power supply at 1.7A limited), and it stayed sharp. After all the graphing, I got the lens out and there are no signs of melting. All the knife cuts from widening the aperture are still crisp. I'm as surprised as you, but my LPM doesn't lie.

 

[Leodahsan]

You didn't inserted the link. Its hyperlinking a phrase.

About Peltier
I just wrote that for a quick reference that solid state heat pumps draw a lot of energy. You can even calculate how much is needed for removing the ~7 watts of heat from the diode. I'm just trying to point out why the 14500 batteries died. :beer:

 

[Zom-B]

Well, oops. hehe. Bad Luck Link? The link was always in my sig too though.

 

[offroadfreak8582]

once in a while you just have a build where everything goes wrong and everything brakes. It can be very frustrating :na:

greetings,,

 

[DTR]

Well I can point out two issues I see just with the module. I think the reason it ran for only a few seconds and dimmed is it overheated. There is virtually no heatsinksing with this mounting you have going there. Also I would get some shrink tubing on those diode pins.

 

[Zom-B]

See that white piece at the bottom? That's the ceramic top of the peltier.

It's true that I had concerns about the temperature, because of the temperature gradient in the aixiz head. When I measured it, it was 25°C at the bottom and 50°C degrees on top (where you see the thin spot of thermal grease)