Test #1 Underdriven 9mm 445nm and Heat

First Tests.

Purpose;
1. To find out the lowest operating power to fully illuminate the diode.
2. To test extreme low powerd heat.

Notes;
1. My Laser Bee is still not here so I can only guess the output of the diode.
2. My 12mm drillbit is not here so this test was done with no heatsink but for the copper module.
3. Items used were a 9mm 445nm diode set in a standard module with a 3 element lens, powered by a Mastech HY1802D.
4. I did not use the G-1 or G-2 as this was to test heat, not output.
5. New IR Thermometer is not here and I dont trust my old one I used my fingers on both sides of the diode.
6. This test was done continuously, only shutting down the power at the end.
7. Room temp is about 72F.

Outcome;
1. At just over 100mA @ 3.5V (5-10mW?) the diode does flicker into life, but is very dim, like a weak LED or so. Run at this setting for 3 minutes. Module still cool to the touch.

2. At about 150mA @ 3.6V the beam kicks on fully. It was very dramatic. Very Bright. Run at this setting for 3 minutes. Module still cool to the touch.

3. At 200mA @ 3.7V the beam is bright enough at 24" on a white wall to make it hard to look at directly. Ran it at this setting for 3 minutes, module still cool to the touch, maybe a tad less so.

4. A few steps later at about 300mA @ 3.8V the beam it self is visable in my sunlit room. Still getting brighter will each step. Ran at this setting for 3 minutes, the module felt neutral, not warm not cool.

5. At 400mA @ 4.0V I can clearly see the beam, Dot is very bright. I ran this setting for only a minute or less before I noticed movement near the focal point. Smoke. Smoke? My wall was smoking. I shut down the power. Tiny hole in my drywall. Up to that point the diode barely got warmer then my finger at about a minute into 400mA

Conclusion of test #1;
1. Diode works wonderfuly at low power.

2. Diode stays cool enough to run for at least 15+ minutes under 400mA with no heatsink (further testing to come as this one was cut short)

3. Dont point lasers as things that can burn. Unless you want them burnt.

Yep but remember underdriving them that much will not let all the lasing lines light up and can give a even more elongated spot. About 1-1.4A is when the last of the outer lines light up filling out the beam profile. But if you were happy with the beam you got @ 400mA then who am I to tell you not to go for it.:beer:

DTR said:

Yep but remember underdriving them that much will not let all the lasing lines light up and can give a even more elongated spot. About 1-1.4A is when the last of the outer lines light up filling out the beam profile. But if you were happy with the beam you got @ 400mA then who am I to tell you not to go for it.:beer:

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I's a start. Just looking to find a balance between heat and light. I am thankful for your help, and all of the other members input and direction. I wish every one shipped as fast as you and Jayrob. Thanks again!

If you're picky you can use an anamorphic prism pair to correct the astigmatism of the multimode diode. May bring it to more of a dot.

Honestly you should just go with the pl450b. Its single mode and has a lower threshold. You will definitely be able to run that diode at a level that will give you unlimited cycle in a fairly small host.

Running a 9mm that low is not very practical, and kinda a waste.

Speedy78 said:

If you're picky you can use an anamorphic prism pair to correct the astigmatism of the multimode diode. May bring it to more of a dot.

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Good idea, but my geometry is lacking. it would take a mass of testing to find what works, and then to fit it into a host I can carry in my pocket? wew. I am not up for that level of a build yet.

benmwv said:

Honestly you should just go with the pl450b. Its single mode and has a lower threshold. You will definitely be able to run that diode at a level that will give you unlimited cycle in a fairly small host.

Running a 9mm that low is not very practical, and kinda a waste.

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I dont see how on Earth I would run the PL405B @ 1w output stable, with passive cooling. It pops around 300mA. That diode would glow red hot even if you could get up to that with out popping. With the 9mm 445's maybe.....

As for my use of a 9mm being a waste, thank you for your opinion. I look at it differently. Just because I own a Viper or a Corvette does not mean I have to drive 200mph. What if I am happy tooling along at 60mph? It does not make my owning an exotic a waste. As long as it does exactly what I want it to do, then it will be perfect, for me. If you want a 3w,4w,5w,6w laser, by all means, build one. I love all of the build threads. If you want a 250mW laser, by all means use the PL405B. :beer:

You are talking about 100ma, 150ma, etc in your post not running it at 1W. This low power, low heat level you are looking for is much more suited to the pl450b. I know you dont have to max it out, but I do believe it is a waste of both money and a diode to run this thing at like 300ma. It isnt even fully on at that current. 9mm 445 diodes are expensive and the other 445 diodes avaliable are cheaper and more functional run at this level.

You dont think its a waste to use a more expensive diode that performs worse (at this level)?

Also, just because the diode is in a 9mm package and can be run much higher doesnt mean it produces less heat. It running at 1A is still about 4W of heat just like an m140 diode.

I think he was assuming you were still going for a 100% duty cycle. You will not get 100% in a handheld without pretty big measures taken. Thats why he was suggesting a great diode that has a nicer beam profile at the output level you would be looking at when all is said and done.

benmwv said:

You are talking about 100ma, 150ma, etc in your post not running it at 1W. This low power, low heat level you are looking for is much more suited to the pl450b. I know you dont have to max it out, but I do believe it is a waste of both money and a diode to run this thing at like 300ma. It isnt even fully on at that current. 9mm 445 diodes are expensive and the other 445 diodes avaliable are cheaper and more functional run at this level.

You dont think its a waste to use a more expensive diode that performs worse (at this level)?

Also, just because the diode is in a 9mm package and can be run much higher doesnt mean it produces less heat. It running at 1A is still about 4W of heat just like an m140 diode.

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I'm sorry, you must have missed my other thread asking questions about this. I don't plan on running it at 300mA. At this point I am thinking of running it somewhere around 700mA-800mA to get a 1W output. This diode will reach a 1W out put with less effort or heat then a M140. My hope is to find a sweet spot between a reasonable sized heatsink set up and performence. I don't want a 30 second cycle time or a 5 pound mag light. WL can do 1W with no cycle time why can't I?

WL can do "1W" with "no duty cylce"....yeah....bout that. Probably not. Marketing BS.

I dont have an arctic so I can really only speculate and relay what I have read.

1. Arctics are usually around 700mw
2. I believe the arctic host is actually pretty big
3. WL are not a respected company because they regularly lie about their products. I dont think the arctic actually has unlimited cycle

In my opinion, you should use the pl450b. It has a much better beam and is the right power level for running an unlimited cycle in a medium to small host. I am nearly positive that you wouldnt be able to run a pl450b at max power in a c6 host with unlimited cycle. I think you would have to run it at 150mw or so.

Think if it like a stepping stone. First the small unlimited cycle laser that you seem to be looking for, and then the big boy active cooled unlimited cycle > 1w 9mm diode build.

benmwv said:

I dont have an arctic so I can really only speculate.


In my opinion, you should use the pl450b. It has a much better beam and is the right power level for running an unlimited cycle in a medium to small host.

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Thanks That actually sounds like the perfect build for my son and I, to make his first laser. He turns 15 next month and has been bugging me about it. As soon as I wrap up these 2 or 3 builds, I'll grab a PL450B after all. :friend:

Tbh I never stick to duty cycles and run my 445 driven by a maxed out flex drive pretty hot. I haven't burnt a diode yet even though I run it for close to 4 minutes in a small hot light host.

If you want unlimited duty cycle perhaps it would be better to go with a custom built ehgemus host? The whole host is one big direct press heatsink and I'm sure it will handle heat better than a c6. Just a tip, try finding a driver that creates close to no heat at your desired current. It will improve your duty cycle.

@sandtiger08
You can attach a LM35 to the module if you live near an electronics store. So you measure temperature precisely.

And that "lowest operating power to fully illuminate the diode" you spoke of is called the threshold current. At that current the diode goes from spontaneous emission (led like light) to stimulated emission (laser like - dramatic change as you said).

IIRC the threshold current changes at different temperatures. But I may be wrong. (don't throw your laser on the freezer to test that uh)

:beer: