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196 445nm diode firing through a standard pane of glass (.25” thick) Bad idea?

behmer

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The title says it all. I have 196 diode‘s packed together in a single array that I’m building an enclosure for. Wondering if a standard pane of glass will present any problems. I should add that the glass is ‘optically clear‘ low iron glass. It doesn’t however have any anti reflective coating.

Thanks
 
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Cyparagon

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A percent or three will be absorbed and a percent or 10 will be reflected. Where will this be installed? What is the power of the array? What is the spacing? What are the weather variables? I can tell you this window (and all laser optics) will need to remain VERY clean at high power, or you risk cracking from thermal shock induced when contaminants absorb light.

We can help you a lot better if you actually tell us what your project is.
 

behmer

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A percent or three will be absorbed and a percent or 10 will be reflected. Where will this be installed? What is the power of the array? What is the spacing? What are the weather variables? I can tell you this window (and all laser optics) will need to remain VERY clean at high power, or you risk cracking from thermal shock induced when contaminants absorb light.

We can help you a lot better if you actually tell us what your project is.

Great to know. It’s going to Burning Man. Running each diode at 1.3w. They are spaced ~1/8” apart.

Given the dusty environment I’m gonna just go with no glass at all given your feedback here.

Will just stay on top of the weather if I see some rain rolling through.
 

paul1598419

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Have you considered the amount of waste heat these diodes will produce and need to be moved away from them and either into the air or some sort of circulating water cooling? That many diodes within an 8th of an inch from each other will get very hot very quickly.
 

behmer

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Have you considered the amount of waste heat these diodes will produce and need to be moved away from them and either into the air or some sort of circulating water cooling? That many diodes within an 8th of an inch from each other will get very hot very quickly.

Yes. Very stable there.
 

Cyparagon

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Given the dusty environment I’m gonna just go with no glass at all given your feedback here.
That's not going to work either. Now the dust contaminates the output window or collimating lens of each diode and is WAY harder to clean.

That many diodes within an 8th of an inch from each other will get very hot very quickly.
It's a lot easier than you might think. I've got a full projector array to run fine using a single blower fan from a server blowing on the rear heat sink. I'd guess OP is doing something similar.
 

kecked

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Use the glass but install it at Brewster’s angle. That will minimize the reflection and prevent back reflection into the diodes which could kill them. You will have two sets of reflection from the different surfaces of the glass. Should be possible. What driver are you running? I’d assum you have them in strings? So like 15 in a string? So what 18 stings of 15. 7v times 15=105v at 2 amps. 200w per string Input power. Will be like running a blow dryer or two. Don’t point it at anyone
 




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