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G-2 Collimator Lens Mishap ?

Accutronitis

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I had this happen just now and I'm thinking there is likely only one cause, Some sort of contamination somehow got on the lens and got fried which cracked the lens ???

It's a DTR G-2 and luckily I have a few of them on hand, Anyone come across this before ???



 



GSS

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I think iv'e heard Alaskan call it a heat fracture?
I don't know if any contamination helps it along?
 

Accutronitis

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I believe when the lens is clean the light is able to pass through the lens without overheating the glass but if enough contamination of the right (or wrong) type is added to the surface of the glass enough light is stopped at the surface of the glass and a sort of thermal runaway quickly takes place at the boundary between the two and the glass pays the price so to speak, it looks like there is a circle of remaining contamination around the "heat fracture" that wasn't "cooked" off before I noticed something was wrong.....

That's my working theory anyways.....
 
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RedCowboy

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That HS compound on your threads can work it's way inside, you need to be sure your diodes window is not contaminated or it will burn through.

 

diachi

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That HS compound on your threads can work it's way inside, you need to be sure your diodes window is not contaminated or it will burn through.

Yeah, at these sorts of powers it really doesn't take much contamination for the optic to be completely destroyed. Your LD window will be even easier to damage than your collimator as it's more fragile and the power density is higher there. The LD window is at least protected from the environment to some extent.

Residue from burning things, dust, grease, they'll all do it. I've cooked lenses from smoke residue after burning something a couple times. Always good to have some air movement and some distance between the optic and your "target".
 
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Accutronitis

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Is this also on the diode window?
No.

That HS compound on your threads can work it's way inside, you need to be sure your diodes window is not contaminated or it will burn through.

It's nice and clean.

Yeah, at these sorts of powers it really doesn't take much contamination for the optic to be completely destroyed. Your LD window will be even easier to damage than your collimator as it's more fragile and the power density is higher there. The LD window is at least protected from the environment to some extent.

Residue from burning things, dust, grease, they'll all do it. I've cooked lenses from smoke residue after burning something a couple times. Always good to have some air movement and some distance between the optic and your "target".
Yes, any time I see smoke try to get close I always stop and wait for the smoke to clear, I always have a fan running in my work room and a lot of the time I have a ventilation fan running as well....
 
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paul1598419

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Fumes from the plastic blades on the ceiling fan you were burning could have been deposited on the lens. That is far worse than cigarette smoke. Anything done indoors is not going to be easily evacuated from the area where you are burning, also.
 
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diachi

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I believe it was a flake of thermal epoxy......
That'd do it, but be careful with smoke too.

Here's what 15W into a lens with contamination from smoke on it will do... Can't really see the cracks for the burn marks...

 
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Alaskan

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Damn man you were pushing some smoke!
 

diachi

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Damn man you were pushing some smoke!
Yup! That lens is also very shot FL, it's for pumping vanadate, so it's closer to the smoke. 15W will make lots of smoke. Hell, it'll get an exacto blade glowing brightly. :eg:

 
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Accutronitis

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Yup! That lens is also very shot FL, it's for pumping vanadate, so it's closer to the smoke. 15W will make lots of smoke. Hell, it'll get an exacto blade glowing brightly. :eg:

Before that blade started glowing I bet it made some strong reflections with 15W striking it ?
 

Alaskan

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Speaking of vanadate, what kind of power do you think a 4x4x8 mm rectangle of vanadate coated 808/1064 nm might be designed to handle? I don't have the percentage of doping. I'm thinking this can take 15 watts of drive at 808nm to produce several watts of 1064 nm out, or is that too conservative?

I don't want to have more than a couple exchanges on this, otherwise the thread will get highjacked, but you brought up vanadate :)

 
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