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ArcticMyst Security by Avery

Dorcy Jr. 1W 445nm build! Lots of pics!

Asherz

Asherz

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RadicalxEdward said:
I'm going to be building a laser very similar to this (basically just a different heatsink) What do you recommend as duty cycle for this? I really don't want to kill my diode.

Also, how do you blow a diode by not replacing the lense?
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Lud was pretty spot on, the lens just basically melts under the heat causing it to reflect more light back into the diode degrading it quickly.

As for a duty cycle it does heat up pretty quick, I'd go with something along the lines of 20-30 seconds, when you get the laser and turn it on hold it until it feels warm to the touch, that's normally when I I'd turn it off and let it cool for a while.
 





Bluefan

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There's 1 wat of light coming out of a tiny facet of the diode. How could unfocused back reflected light do anything?
 
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RadicalxEdward

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Asherz said:
Lud was pretty spot on, the lens just basically melts under the heat causing it to reflect more light back into the diode degrading it quickly.

As for a duty cycle it does heat up pretty quick, I'd go with something along the lines of 20-30 seconds, when you get the laser and turn it on hold it until it feels warm to the touch, that's normally when I I'd turn it off and let it cool for a while.
Click to expand...

Thanks for the info. That's pretty much inline with what I was expecting for such a small device.

I'm getting excited seeing everyones projects. My microboost drive should be in today. next up is just goggles and the diode. (^_^) Can't wait to get it all together.
 
Asherz

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Bluefan said:
There's 1 wat of light coming out of a tiny facet of the diode. How could unfocused back reflected light do anything?
Click to expand...

Because they're particularly sensitive, and the amount of heat the light produces is quite a bit, if it's reflecting a 200mW's of diffused light in a very enclosed space (front of the module) that light is bound to hit the facet and increase heat levels, not causing instant death but degradation non the less, I've heard of people accidentally pointing the laser in a mirror, the beam then bouncing back and going back into the laser module and blowing the diode.
 
Bluefan

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It will add heat, but say 20% of a 25% efficient diode is 5% extra heat, not much. The facet it tiny and already has a watt pasing through, the part of the back reflection arriving at this tiny facet is probably not even a milliwat, so no problem here.

Hitting a mirror is different from a backreflection from a lens, a lens backreflection is not focused and has a low intensity (W/m^2). A reflection from a mirror back to the laser will again be focused on the diode, doubling the intensity at the facet or burn somewhere else on the diode. That easily could kill a diode.
 
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RadicalxEdward

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and how many mA are you guys running at for 1W dorcy's?

My basic electrical understanding was that if you wanted a 1W laser, it'd be run at the voltage of the diode and W/V for the amps. But I've seen people talking about running a 1W laser at 1A. How can you do that if the battery starts at 3-4 volts. Wouldn't that mean if it's running at 3-4 volts @1A it would be 3-4 watts? (minus resistance and heat)

One of the reasons I'm building this is to get a better grasp of these rudimentary electrical concepts.

Thanks!
 
ludwigfan

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My understanding is that optical output power is different from electrical power. Although both are measured in Watts. As for where the power goes, it goes into light and heat.
 
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ludwigfan

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I once read that they are different. Although I can't find what the difference between them is after searching online for a bit.

The units are the same, so if they are equivalent, which I'm not sure of right now, that indicates that the diode is converting ~1/3 of the power into light. The rest is probably given off as heat by the diode as well as the driver.
 
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RadicalxEdward

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ludwigfan said:
I once read that they are different. Although I can't find what the difference between them is after searching online for a bit.

The units are the same, so if they are equivalent, which I'm not sure of right now, that indicates that the diode is converting ~1/3 of the power into light. The rest is probably given off as heat by the diode as well as the driver.
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Which makes sense considering how you need a heatsink and short duty cycles to even run it at that much power.

I found this equation for measuring output power with a dmm and solar panel. "Current in amps as shown on the DMM multiplied by 1239.7 divided by 445 divided by 0.97. The result should be your laser power in milliwatts. "

I'll be sure to post pics of my build and see what I can get out of it without frying it. (REALLY hoping I don't fry it, cause it ain't cheap for me, so i'm gonna start with the power lower and move up)
 
ludwigfan

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By burning it out do you mean the solar panel or the diode/driver? I think you mean the laser itself. But I wonder how much the solar panel can take. The "pros" use a thermopile to detect laser power. I think that is because solar cells may not be linear in voltage or current with respect to number of incident photons.

Incidentally (no pun intended) I found a website online where you enter in power in watts and wavelength in nm and it calculates number of photons for you, pretty neat. I'll try and find it again and post it.
 
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RadicalxEdward

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Well I finally got it built. and it looks nice and all. but it's tough to burn anything at all. nothing like i've seen around. I can't even light a match (with it properly focused). Potentiometer on microboost drive was turn all the way clockwise. I'm trying to search the help forums but haven't come up with ideas why yet. I suppose my battery may need to be replaced or something. My DMM says it's at 2.84 volts, which is kinda low I guess considering the microboost will shut off at 2.5 but the batt is only 3v to begin with.
 
ludwigfan

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RadicalxEdward said:
Well I finally got it built. and it looks nice and all. but it's tough to burn anything at all. nothing like i've seen around. I can't even light a match (with it properly focused). Potentiometer on microboost drive was turn all the way clockwise. I'm trying to search the help forums but haven't come up with ideas why yet. I suppose my battery may need to be replaced or something. My DMM says it's at 2.84 volts, which is kinda low I guess considering the microboost will shut off at 2.5 but the batt is only 3v to begin with.
Click to expand...

Don't you mean the battery is 3.6V? And shouldn't it be at least 3.7 to 4.2 fully charged?
 
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RadicalxEdward

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It's definitely the battery. With the stock battery in it's basically a laser pointer. But I rigged up a pattery pack from a flashlight (3 AAA) and it works GREAT. smoked a black cd case instantly and burned through in just a couple seconds. after a couple minutes of off/on use (mostly off) the heatsink got a little warm and the diode starts blinking, getting faster and starts emiting a high pitched sound corrosponding to the blinking. Is this what happens when it starts to over heat (the heatsink never even got warm with the stock battery.)
 
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