"nuny at (no spam) bid.nes" <Alien8752 at (no spam) gmail.com> wrote in
news:1ebbff3c-5d59-441e-a4a7-fcf8a6f66d35 at (no spam) s33g2000pri.googlegroups.com:

Snipola
an image on the retina.

Snipola
I'm not entirely sure of that re: holography.

I have no experience making holograms, and as such, I don't see
why making a hologram "out of focus" in such a way that requires
a lens to view that is equal to one's prescription wouldn't work.

Actually, I think if you shot the image through your glasses
would work.

In article <KHPTj.41565$2Y1.13... at (no spam) newsfe30.ams2>,
i... at (no spam) oblivion.nothing.com says...

"n... at (no spam) bid.nes" <Alien8... at (no spam) gmail.com> wrote in
news:1ebbff3c-5d59-441e-a4a7-fcf8a6f66d35 at (no spam) s33g2000pri.googlegroups.com:

Snipola
an image on the retina.

Snipola
I'm not entirely sure of that re: holography.

I have no experience making holograms, and as such, I don't see
why making a hologram "out of focus" in such a way that requires
a lens to view that is equal to one's prescription wouldn't work.

I do,

and what you propose is simply impossible. There is no way
to
produce a hologram that is "out of focus". If you see an real object at
arms length as fuzzy, you will see a hologram of that same object as
fuzzy also.

Actually, I think if you shot the image through your glasses
would work.

You normally don't shoot a hologram through a lens, and if you did, you
end up with a hologram of a lens. The hologram of the lens would work
just like the original, for other objects captured by the hologram.

So, you could make a hologram of your eyeglasses in front of a book, and
be able to read the book through the eyeglasses. However, someone with
better vision would simply see the image as distorted by the lens, but
not out of focus. And, it being a holgram, they could simply change
their viewing angle and read the book over the eyeglasses.

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.

On May 3, 9:59 am, "CWatters"
colin.watt... at (no spam) NOturnersoakSPAM.plus.com> wrote:
"Amir Michail" <amich... at (no spam) gmail.com> wrote in message

news:f5527a1b-d89b-4767-bcbf-2bc88cadfe33 at (no spam) d1g2000hsg.googlegroups.com...

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

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.

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


Mark L. Fergerson

So maybe this is possible as well?

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.


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.

Amir Michail writes:

So maybe this is possible as well?

No. Corrective lenses must be near, or on (as in contact lenses) the eye.

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.

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.

On May 8, 3:51 pm, Boxman <box... at (no spam) voyager.net> wrote:

  That's why I suggested shooting a hologram through one of my
eyeglass lenses (or its prescription's dual); the lens "encodes"
exactly the relevant distortion, yes?

No.

That's why I suggested shooting a hologram through one of my
eyeglass lenses (or its prescription's dual); the lens "encodes"
exactly the relevant distortion, yes?

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?

I'm not entirely sure of that re: holography.

You cannot change the reconstructed wavefront to accomodate an
aberrated eye. You will create geometrical distortion in the
reconstructed image.

Amir Michail writes:
So maybe this is possible as well?

No. Corrective lenses must be near, or on (as in contact lenses) the eye.