Re: optical 'virtual objects' have depth

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

Hi All,

>P3D Peter Abrahams  <telscope@xxxxxxxxxx> wrote:
>.....The lens forms a 3-d image of the object, in air.  In what other mediums
>would it form a similar image...water, glass, lucite.   
>What are the possibilities of being able to see that image in that medium?  
>.....
>I believe that none of the above are feasible, which leaves:
>If any 'virtual object', focused by a lens, is in fact fully three
>dimensional, is it at all useful in that form?

You would have to selectively provide the point of reflection as a moving
plane throughout the medium so that each point doesn't interfere with either
the light path to other points or the viewed image from a set of points. You
would also have to provide illumination of the object to correspond to the
plane of presentation for each moment in time. 

Something similar seems to have been done a while back using a large mirror
that oscillated between concave and convex. The computer screen (or video?)
was viewed through reflection off of the mirror. Movement of the mirror
placed the virtual image at different points in space so that when the
oscillations of the mirror matched the presentation of image planes on the
screen, the result was a 3D view of the subject.

Some patents seem to deal with using the virtual image. One example is the
optical toy that you may have encountered which uses two concave mirrors
attached to and facing each other. The one on top has a hole cut into it's
center so that you can look inside. A small object can be placed into the
arrangement. It will of course sit on the bottom mirror. When you look
casually at the hole in the top of this device a virtual image of the small
object is presented in the hole such that the small object appears to be
floating in the actual hole opening. When you look directly down inside, you
see that it is really on the bottom of the device.

A newer technology called HDVD seems to use the virtual image principle but
it reconstructs the image so piecemeal that the location in space of each
part of the image is fully controllable. This allows them to use ordinary 2D
images which are projected into this virtual space. Portions of the image
are optically positioned wherever desired to construct a 3D virtual image
from the 2D source. It's very expensive and uses lots of optics to do this
but I believe it is a way of using the virtual image that you were speaking of.

You can look into it for yourself if you like by visiting several sites on
the web below.

        Discover Magazine award for tech innovation, category "sight"
        http://www.enews.com/magazines/discover/a96st.html

        CRL(London) in association with DMA (New York)
        http://www.tecrl.co.uk/futures/mirrors.htm

At $12,000 to $32,000 for the basic equipment I don't think it will see
common use too quickly. They claim that within a couple years the system
will be mass produced and be more cost effective and will start appearing in
consumer products. Time will tell.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/


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