Re: CD diffraction

[brian whatcott <inet@INTELLISYS.NET>]

At 12:17 4/26/99 -0500, you wrote:
> This was after the diffraction grating lab today. A student
> wanted to see the effect of a CD on light. I turned the
> laser on and we at once saw the central strongly reflected
> beam, then two less strong beams at about 30 away, and
> another par at about 60 degrees etc. I was happy to say
> "this is m=0, these are |m|=1, 2, etc.".
>
> Then the beam of white light was reflected. What we saw
> was a band of white light. We expected the band to show
> colors, as from the diffraction grating. But there were no
> colors. Why? Details on how to disperse colors with a CD
> will be appreciated.
>
> Ludwik Kowalski
Ludwik sees a very prominent spectrum reflected via a CD
from an incandescent lamp into his eye, as do we all, and wonders
why he cannot project a spread image.
   We conclude the light is remixed to white, and that to
hold the colors separate, a slit followed by a collimator lens
playing on a fairly narrow segment of the CD will surely serve
the purpose.
 That's my thought at least - perhaps I can try it in practice
this evening....

Brian
brian whatcott <inet@intellisys.net>
Altus OK