Alright, let’s say your pointing a laser beam at a reflective surface. We all know that light reflects, so the beam should relfect right? Correct me if I am in fact wrong. So, if the beam reflects, would it retain it’s heat energy, or would it lose the heat energy to the surface it bounced off of?
Psychopatchik Vampire
It depends; radiant heat and light are the same thing (just different wavelengths - if the surface is totally reflective to all of the wavelengths in the beam, then it will reflect the heat, if it is reflective only to some wavelengths, these will be reflected and the others absorbed, warming the (partially)reflective object.
Only that energy absorbed would be dissipated as heat. All other energy would remain in the beam, I guess.
Laser light is not two things, it’s not light plus heat energy. It’s just light.
When it bounced off a mirror, if it lost anything, then the reflected light would become dimmer.
PS, when a visible-light laser is powerful enough to heat an object, it’s not because the laser beam contains any infrared. It’s the visible light that causes the heating.
In other words, infra-red light is not “radiant heat”. Instead, ALL LIGHT is “radiant heat.” People get confused because IR light is invisible to human eyes. If bright IR light shines on your, your skin gets hot, but you can’t see any reason for this, so you might come to believe in a bizarre stuff called “radiant heat.” You’d be wrong. In truth, any kind of light will heat up an object if the object absorbs the light. Does an electric heater warm your backside? It’s only because the heater is sending out very VERY bright light. (But the color of that light happens to be invisible to human eyes.)
Many lasers contain mirrors as an integral part of their design, so the mirrors had better reflect most of the energy hitting them.
Thanks for the detailed replies, guys.
Psychopachik Vampire