Re: IS IT A LASER?

From: Haisheng (haisheng_at_gmail.com)
Date: 10/18/04 

Date: 18 Oct 2004 00:33:05 -0700

Thank you all for responding to my post.

My question was really a basic (or fundamental) one rather than a
practical one. Historically, laser has been labeled with "highly"
coherent, bright, and directional. However, these properties are all
relative. How coherent/bight/directional a light source has to be in
order to be qualified as a laser? Without knowing how the light is
generated in a "black box", can one determine whether the light is
from a laser in that box or something else, by measuring the light
beam properties such as power, divergence, wavelength, spectrum,
coherence, etc.?
        
Btw, observing speckle is a practical and easy way to get an idea
about the coherence of the light source. There are better ways to
determine coherence of a light source, such as interferometry, etc.
But even so, what degree of coherence is the "qualification" for a
laser.

Thanks,

Haisheng

Ian Stirling <root@mauve.demon.co.uk> wrote in message news:<417298c2$0$59441$ed2619ec@ptn-nntp-reader03.plus.net>...
> In sci.optics Haisheng <haisheng@gmail.com> wrote:
> > My question is very basic:
> >
> > How can you tell for sure whether a light source is a laser or not?
> > You can measure whatever you want, but not touch the source.
>
> Look for a Class I/... laser label that must be affixed to all products
> emitting laser beams.

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