Perhaps a bit nit-picky, but holograms aren't  a "stereoscopic effect"
in the sense that you purposely send two different images to each
eye.  Holograms reproduce the original wavefront that came from the
object that the hologram was made from.  If you have one eye,
theoreticially you will still perceive similar depth in the hologram
as you would viewing a real scene with one eye.  Obviously with 2 eyes
you have greater depth perception and the depth observed in the
hologram will appear accordingly.

In regards to the topic of trying to create a hologram that is "out of
focus" for normal viewing but in focus for an uncorrected nearsighted
person for example, this is only possible if you know ahead of time
the distortion that your eye adds to the wavefront entering the eye
and then somehow perturbing the hologram to create a distorted
wavefront that when passed through the nearsighted eye creates the
proper wavefront at the eye.  I know of no mechanism available during
the recording of a hologram that would be able to create such a
distortion.

It is probably feasible to calculate and then create a computer
generated hologram that would distort the wavefront coming from a
monitor such that when it entered your uncorrected eye the image
appeared focus.  I think a practical problem is that you would lose a
significant amount of brightness because hologram diffraction
efficiencies are usually low (meaning a lot of light will get thrown
out of the "main beam" and not enter your eye).  It also may only work
over a small angle, meaning it would only appear in focus straight on
and a few degrees to the left/right of straight on.

Nope. It means you have a problem focusing on distant objects. It doesn't
mean obects appear to you to be at the wrong distance. Important difference.

Holograms are all about reproducing an effect caused by stereoscopic
vision - which needs two eyes. They make parts of the image appear nearer or
further away by presenting each eye with a different image. If you only have
one eye you can't see the 3D effect.

Aside: If you only have one ey you can see _a_ 3D effect if you move your
head or the hologram but that's a different 3D effect. In that case you are
seeing something more akin to a sequence of 2D images.

On May 3, 9:59 am, "CWatters"
<colin.watt...@NOturnersoakSPAM.plus.com> wrote:

 Beg pardon? I am "nearsighted". Guess what the term means.

 Mark L. Fergerson

I don't think so... People who need glasses don't have a problem seeing
things at the wrong distance - so correcting the apparent distance using a
3D effect doesn't help.

Imagine using a laptop without having to wear corrective
eyeglasses.

I know that 3D displays exist that don't require special glasses.

So maybe this is possible as well?

Amir