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Burnt thermopile, how bad is this?

Joe Mo

Joe Mo

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Well, I put my 532nm on the LPM while it was slightly focused, I didnt realize it before it burnt some small lines on the surface of the sensor. How bad is this? the line is maybe .25" long. I'll post pics when I'm home from work.

Thanks guys.
 





How in the world do you burn a Thermopile by having it slightly focused?

I measure all the time fully focused and if it burned my Thermopile I would send it back to the manufacture IF you are within the power range the Thermopile is rated for.

Now if you exceed the power rating of the Thermopile, well then all bets are off.........Is that perhaps what happened?
 
electron said:
How in the world do you burn a Thermopile by having it slightly focused?

I measure all the time fully focused and if it burned my Thermopile I would send it back to the manufacture IF you are within the power range the Thermopile is rated for.

Now if you exceed the power rating of the Thermopile, well then all bets are off.........Is that perhaps what happened?
Click to expand...

probably so, I would say it was fully focused, I just had the laser 8 inches away when it happened. it was completely focused at that distance.:yabbem:
 
I have many powerful Lasers that I can't even adjust the focus on them, other than perhaps to adjust the distance from the Laser to the Thermopile.

As long as you stay within the power range of the Thermopile it shouldn't burn the coating, as it's rated for a certain range.

I just did a quick check of my manual and there is no requirement to do that, other than not to exceed the range of the Thermopile so that you don't damage the coating; that is what Coherent's manual says.

You might want to check your manual and see what the Thermopile is rated for so that you don't burn the coating.
 
electron said:
As long as you stay within the power range of the Thermopile it shouldn't burn the coating, as it's rated for a certain range.
Click to expand...

Thats your answer Joe. Maybe you should talk to the person who sold you the thermopile.
 
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I have the same LPM. You have burn the black paint of the TEC. The TEC surface is ceramic, you can't damage it unless you have a 20Watt CO2 laser.
The LPM will still work but the absorption of the laser power will be less. You need to use the undamage surface of the TEC. The area is 40x40mm, still enough space left.
 
Ahh I see now, it's a TEC that was painted black being used as a thermopile, that's why it burned, it's black paint. Did it come with any instructions that would allow you re-coat it, and then do a calibration using resistors perhaps? some work that way.

Please DON'T just re-paint it, you'll ruin the calibration it already has. It would be best to contact whom ever you bought it from and see if they can help you OR just do as Blord says and try and live with it the way it is; sorry to hear this.
 
Blord said:
I have the same LPM. You have burn the black paint of the TEC. The TEC surface is ceramic, you can't damage it unless you have a 20Watt CO2 laser.
The LPM will still work but the absorption of the laser power will be less. You need to use the undamage surface of the TEC. The area is 40x40mm, still enough space left.
Click to expand...

this seems correct, also thank you electron and TJ for the info will do!
 
For now if the burn spot is small, just avoid it when testing lasers and the LPM will still read accurately. To fix the burn though you'll need to send it back and have it recoated + recalibrated.
 
Joe Mo said:
Well, I put my 532nm on the LPM while it was slightly focused, I didnt realize it before it burnt some small lines on the surface of the sensor. How bad is this? the line is maybe .25" long. I'll post pics when I'm home from work.

Thanks guys.
Click to expand...

Did the Seller give you a Minimum Beam Profile diameter at Max
rating of your LPM.....:thinking:
Did the seller specify a Maximum Power Density of the Thermpile
head (W/cm2)... :thinking:

If the damage is small and not too wide or deep you could use an
unaffected area of the sensor as was suggested or widen your
Laser's Beam Profile as large as you can. This way any error will
be minimal.


Jerry
 
Last edited:
lasersbee said:
widen your
Laser's Beam Profile as large as you can. This way any error will
be minimal.


Jerry
Click to expand...

Exactly. Power is power. As long as its all on the sensor area you should get a good reading.

Look at me giving LPM advice. :wtf: :whistle:
 
hah! thanks guys, just started this hobby :) my last hobby was overclocking
 
Im getting a new mobo / CPU next month hopefully, I may call on your expertise :)

/topic
 
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