Does anybody know?

magic

gnomes and hobo stew plus the eye of a newt. Or what he ^  said.

It's not a laser, the laser is just for knowing exactly what you're pointing at. Just like on a firearm.

There's a sensor in there, essentialy an IR light meter, that can read the temperature of the surface it's aiming at from the wavelength of IR light it's giving off.

I believe he's correct.

Very interesting. Thanks

It can't just read the wavelength, that could change based on the material.  Instead, it reads the intensity.  The meter has to be close enough that the entire cone of measurement is viewing the object to be measured - like a narrow-view video camera, it has to be close enough that it can't "see" anything else.

You do have to know the emissivity of the object you are measuring.  For instance, an object made of polished aluminum will have an emissivity of around 0.01 whereas a piece of say coal will have an emissivity of around .99, so a piece of coal at the same temperature will be giving off 99 times more infrared radiation than a piece of aluminum.