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I think i burned out my laser?

K

kaminsknator

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I'm building my first laser project with the end goal being a laser engraver capable of cutting vinyl.

The diode I chose was a 300mw 808nm: 808nm 300mW 5 6mm TO18 High Power Burning Infrared IR Red Laser Diode Lab 2 2V | eBay

I made a driver with an lm317T and bought this casing: 808nm Laser Module Host for TO18 5 6mm Laser Diode with 3 Elements Glass Lens | eBay

Powering up the diode it looked more like a fuzzy flat line rather than a dot. For pushing 400mA, the upper range on the data sheet, I found I needed a 3 Ohm resistor for the feedback path. After turning it on and measuring the current it was at 800mA. I'm assuming that the diode is damaged although it operates as originally it doesn't burn anything.

Is there an error in my method? Will the case focus properly?
I would like to stay with this wavelength as I already spent a good bit of money on safety glasses; more than on everything else. Should I just go with a premade module like this: Professional Laser Diode Driver for 808nm 532nm 660nm with TTL | eBay

Any recommendations on my next diode if this one is junk? Or up to 500mW 1pc to 18 5 6mm 500mW 808nm 810nm Infrared IR Laser Lazer Diode LD No PD | eBay
 
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Eudaimonium

Eudaimonium

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How are you measuring the current output of the driver? Can we see a pic of your setup? You most definitely shorted something out, or used wrong resistor, or somehow made the driver output the incorrect amount.

Also yeah the diode is DEFINITELY fried. Destroyed diodes still give off light, albeit a very faint light, we call it "LEDing", you have LEDed your diode. Basically it gives off some light emission, but not coherent laser radiation because the emitter got destroyed, and now it's more like an LED emitter.

If you plan on doing PWM or TTL on/off switching, you should get that premade driver if it's built for that. Driving the diode at constant current is easy enough and should be done with DIY drivers in most cases.

Any additional functionality raises the "DIY" part difficulty substantially.
 
diachi

diachi

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kaminsknator said:
I'm building my first laser project with the end goal being a laser engraver capable of cutting vinyl.

The diode I chose was a 300mw 808nm: 808nm 300mW 5 6mm TO18 High Power Burning Infrared IR Red Laser Diode Lab 2 2V | eBay

I made a driver with an lm317T and bought this casing: 808nm Laser Module Host for TO18 5 6mm Laser Diode with 3 Elements Glass Lens | eBay

Powering up the diode it looked more like a fuzzy flat line rather than a dot. For pushing 400mA, the upper range on the data sheet, I found I needed a 3 Ohm resistor for the feedback path. After turning it on and measuring the current it was at 800mA. I'm assuming that the diode is damaged although it operates as originally it doesn't burn anything.

Is there an error in my method? Will the case focus properly?
I would like to stay with this wavelength as I already spent a good bit of money on safety glasses; more than on everything else. Should I just go with a premade module like this: Professional Laser Diode Driver for 808nm 532nm 660nm with TTL | eBay

Any recommendations on my next diode if this one is junk? Or up to 500mW 1pc to 18 5 6mm 500mW 808nm 810nm Infrared IR Laser Lazer Diode LD No PD | eBay
Click to expand...

IT sounds like you killed it, but even if not, you aren't going to see much more than a "fuzzy flat line" at 808nm anyway. Best way to tell is focus it to a spot and see if burns or use an LPM.

I'll second Eudaimonium's question about how you measured the current. If it truly was 800mA then your diode is likely dead. One thing to keep in mind is that you should avoid powering the driver without some sort of load attached, and you should short out the output leads before attaching the diode as some charge may be stored in any output capacitors at a higher voltage than the diode is rated for.

Eudaimonium said:
Also yeah the diode is DEFINITELY fried. Destroyed diodes still give off light, albeit a very faint light, we call it "LEDing", you have LEDed your diode. Basically it gives off some light emission, but not coherent laser radiation because the emitter got destroyed, and now it's more like an LED emitter.

Any additional functionality raises the "DIY" part difficulty substantially.
Click to expand...

Keep in mind he's using 808nm, so all he is going to see anyway is a very faint light.
 
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K

kaminsknator

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I'll post some pictures later but to measure the current I pulled the lead from the diode out and ran it in series with my multimeter. I'll subscribe to the thought that i've LEDed my diode.
I don't have a filtering cap on the output, only on the input.
Eventually I would like to have it controlled with a microcontroller so I'll get that driver I suppose. Thanks for everyones input. Any diode suggestions or just drive on with the above?
 
Eudaimonium

Eudaimonium

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kaminsknator said:
I'll post some pictures later but to measure the current I pulled the lead from the diode out and ran it in series with my multimeter. I'll subscribe to the thought that i've LEDed my diode.
I don't have a filtering cap on the output, only on the input.
Eventually I would like to have it controlled with a microcontroller so I'll get that driver I suppose. Thanks for everyones input. Any diode suggestions or just drive on with the above?
Click to expand...

NEVER ever break a connection between the driver and the diode when the circuit is powered!

It's just the way drivers work. It basically destroys both the driver and the diode.

If you need to measure the current, either measure it before the driver (between battery and driver, only works with LM317 and derivates), or use a test load.

 
K

kaminsknator

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I did attach a test load first although because my diode had a 2.2V drop i only used 4 1n4007 diodes in series to simulate the LD. I did however use the same method for current testing as breaking the circuit and putting it in series with my multimeter.
 
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