Constant Light without a source?

[Kazza]

Constant Light without a source?

Is it possible to create a constant light using a laser pointer and two highly reflective parabolas. If the two parabolas open out to face each other, and then you shine the laser into one, would the laser reflect until it reaches the centre and then continualy bouncing back and forth creating a constant light, at this point turning the laser off cause there to be no light source. Eventually this would fade out but is it possilbe.
Any ideas on where to buy products for this would be usefull.

 

[Nabeshin]

In theory, an idea such as this should be possible. However, in order for the light to be seen, it has to diffract off of the air, which obviously diminishes the beam strength. Also, since no mirror is perfect, even in a vacuum the beam would not continue to propagate infinitely.

 

[turin]

I don't expect this to be possible for visible light, or EM radiation of wavelength shorter than microwave. Anything you make the mirrors out of will be composed of atoms, and so the granularity will have a deteriorating/dispersive effect on multiple reflections. There can be a few, or even a few hundred reflections, but very soon the light will scatter out of the apparatus. Unfortunately, for much longer wavelengths you have another problem: heat loss.

 

[Andy Resnick]

This sounds very similar to the principle of ring-down spectroscopy; the "residence time" of light in a cavity is a very sensitive measure of what is in the cavity.

http://en.wikipedia.org/wiki/Cavity_ring_down_spectroscopy

 

[Kazza]

This sounds very similar to the principle of ring-down spectroscopy; the "residence time" of light in a cavity is a very sensitive measure of what is in the cavity.

http://en.wikipedia.org/wiki/Cavity_ring_down_spectroscopy

Wow, I didn't know there was such a thing. Thanks for opening my eyes.
Cheers

 

[Archosaur]

Is it possible to create a constant light using a laser pointer and two highly reflective parabolas. If the two parabolas open out to face each other, and then you shine the laser into one, would the laser reflect until it reaches the centre and then continualy bouncing back and forth creating a constant light, at this point turning the laser off cause there to be no light source. Eventually this would fade out but is it possilbe.
Any ideas on where to buy products for this would be usefull.

Keep in mind that the only light you see is light that has left the system of mirrors.