Coherent light without laser -- possible?

[Green Xenon]

Hi:

 

Is it possible to generate coherent light with a device other than a laser? If so, has this ever been done before?

 

 

Thanks,

 

Green Xenon

[John Cuthber]

Yes, you can do it badly.

The first holograms were made without lasers.

Strictly, this wiki page

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

about the inventor is wrong.

You can't make holograms without coherent light.

[swansont]

The thing is, coherence isn't really a discrete condition. Laser light will eventually lose its coherence after some distance — if you put light through a delay line and interfere it with the source light (i.e. having one arm of an interferometer be really long) eventually you will lose contrast on your interference.

 

I thought that Gabor used emission light that was spatially filtered, giving it some degree of coherence.