Weird Radiometer Burning Effect

[Xplorer877]

I was messing around with my radio meter using my LOC to make it go when I noticed something odd. I saw a very bright pale gold flash appear for a second then disappear. I realized that my laser was focusing on the black foil sail and was burning the carbon (I think it's carbon) coat on the sail. It works with any wavelength. There is no oxygen in those radiometers so it doesn't technically burn it just get's very bright. It's a really cool effect. I tried to take a vid and pictures but they're not a good representation of the effect. It closely resembles an incandescent light. It's like a natural or warm white color. I tried it with both of my radio meters (two different types) and it worked with both of them. I'm tempted to crack open my cheap one to get a better look but perhaps the effect won't work the same if it's in the presence of oxygen.

Here is a video:


-Tony

 

[Morgan]

LOC? It looks like IR light from the video? Interesting effect though. I can offer no explanation other than flourescence.

M

 

[Xplorer877]

No that's 405nm in the video. It's not florescence because it only happens when a powerful laser is focused to a point. I think the laser is heating the material and making it glow like the filament in a light bulb.

-Tony

 

[Seoul_lasers]

I have seen this exact phenomenon before with black paint ( with carbon in it) and my 660nm 300mW LPC-815 lab laser. What you have there is Thermoluminescence brought on by the radiometer black vanes paint absorbing the laser radiation. As the paint gets hot enough (decomposition at high temperature) it starts to emit light. Carbon is extremely easy to get white light from when it's hot. This is why it was used in arc lamps.

 

[Xplorer877]

That sounds about right. Hmmm pretty cool!

-Tony

 

[Cyparagon]

Don't do it too often. You'll eventually vaporize enough of the material to begin to compromise the vacuum.

 

[Xplorer877]

I've already noticed that....:cryyy:

-Tony

 

[Meatball]

I believe radiometers are not a complete vacuum... there must be SOME air inside the bulb to 'push" back on the black side of the fins. If it were a vacuum, the entire affect would not work. Your radiometer should be fine.

 

[mbessey]

Yes, there's some air in the radiometer, but not full atmospheric pressure. Most likely you're actually burning the paint.

 

[Cyparagon]

Yes, if you want to be an ass about it, there's no such thing as a perfect vacuum.

 

[Seoul_lasers]

Yes, if you want to be an ass about it, there's no such thing as a perfect vacuum.

Hey! I don't think he ment to be an "ass", he was just explaining.

 

[aXit]

Carbon doesn't need to get that hot to emit light. Even the yellow part of candle flames is just heated carbon.

 

[Seoul_lasers]

yes, indeed. Carbon is very thermoluminescent. We are talking white light from carbon which you do need to get EXTREMELY hot. The point at which the white light is created is about 5800K as in a carbon arc light, actually carbon sublimes at this temperature under normal atmospheric conditions.

 

[Cyparagon]

2100k is arguably "white", sir.