CD's as parabolic mirrors?

From: Dave McGuire <mcguire_at_neurotica.com>
Date: Fri Dec 8 16:35:56 2000

On December 8, Megan wrote:
> >I remeber reading that a hologram of a lens would refract light in the
> >same was as a real lens would. This concept has formed the basis for
> >the flight-of-fancy holodeck/holosuite concept from Star Trek.
>
> <ot>
> The holodeck supposedly uses both hologram projectors and transporter
> technology... I suspect it should also use shield technology, too...
> </ot>

  The Trek world's holodecks don't have anything at all to do with
holographic lens technology. They use a combination of holography
(for background scenes and "wall extension") and transporter-style
matter synthesis for "solid" objects.

  Yes, though, holographic lenses do work, are in widespread use, and
have been around for quite some time.

  The most recent consumer application for them jumped out at me at a
hamfest last summer. Some guy had dozens of cases of new, really
cheap & cheesy handheld laser pointers. The more expensive ones (like
$8 instead of $5) came with these little interchangeable "caps" that
you could screw over the beam exit end. These different caps
contained holographic lenses which would project different patterns or
pictures or whatever on whatever you pointed it at.

  Yes, there are some of those things on the market that simply
contain a piece of what looks like miniature slide film...but if you
look around, you can find the ones with the holographic lenses. They
kinda look like plastic diffraction gratings when viewd in normal
light.


        -Dave McGuire
Received on Fri Dec 08 2000 - 16:35:56 GMT