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-   -   Polyplanar optic display (http://www.avsforum.com/forum/23-screens/19320-polyplanar-optic-display.html)

dcottle 01-03-2001 04:59 PM

I came across a reference to this display technology, which essentially is a planar optical fiber. Hundreds or thousands of thin glass or plastic sheets are stacked together separated by reflective black layers. One end is cut normal to the stacking of the layers, while the other end is cut at an angle. A device such as a DLP projector reflects light into the first end, and light is emitted at the angled end which comprises one line of horizontal information.

The device apparently provides excellent blacks and seems similar to a rear projection screen, but requires only a few inches of depth instead of feet.

See http://www.dne.bnl.gov/~jimv/

Dave

KFung 01-03-2001 07:52 PM

Sounds intriguing! I wonder what kind of resolution they get out of this? They stated that they were using extruded acrylic with a thin layer of black as well, I wonder if they can get both layers thin enough that is doesn't affect resolution? It also sound like they would need a whole new optical engine for the projector because it has to project a long, thin image into the bottom of the screen. Our throw distance woes may be solved yet!

Regards,

Kam Fung

noah katz 01-04-2001 05:46 PM

Very interesting. But I don't see where throw distance has been taken out of the equation; at best it looks like you can trade depth for height.

Thanks

dcottle 01-04-2001 05:56 PM

Another reference which is somewhat more detained is http://www.abptuf.org/T2007/ol5/unique.html, although it is without schematics.

Dave

KFung 01-04-2001 06:01 PM

Ahhhh, but it might...

The image that is projected into the bottom of the screen is very narrow, but wide. The narrow nature of the image means that the mirrors for a rear-projection application could be similarly narrow. This would allow you to use many mirrors to add more throw without as much cost or space as a regular rear-projection system.

Regards,

Kam Fung

dreamer 01-04-2001 06:13 PM

The article is a bit brief on how the light is spread over the planar acrylic. I don't quite get it.

A few years ago, I remember seeing an article in Popular Science that was similar but easier to see how it works. You take a bundle of two million fiber optic strands, one per pixel. This had a flat cross section of rectangular shape that was relatively small -- say 4" x 3". You project onto it. the other ends of the fibers are arranged behind a glass or acrylic plate -- but spaced out behind microlenses such that they "project" a pixel that is larger than the fiber. End result is an image whose size is related to very slight changes in distance from microlense to faceplate. The length of the fiber optic strands is just long enough to reach the proper position behind the faceplate, and has nothing to do with "throw". And the fiber is flexible and can snake its way in from the side, bottom or wherever. So the end result was a display device a few inches thick.

This was purely a conceptual article. No working demonstration. I have no idea if anyone is actually working on it. But I think the basic idea is the same as this planar device -- the light-pipe spreads the image and it is not necessary to have a projector form the image long-and-skinny.

Of course, 20 million feet of fiber optic cable seems like it might be expensive !

[This message has been edited by dreamer (edited 01-04-2001).]

noah katz 01-08-2001 07:40 PM

Kam,

"This would allow you to use many mirrors to add more throw without as much cost or space as a regular rear-projection system."

Sounds right at first blush, but I think getting the narrow image expanded back to its normal dimension cancels the benefit by requiring that much more throw distance.


markm 01-08-2001 07:49 PM

Sorry guys, it's a real POS. Those guys have been trying to sell (a major un-named aeorspace company, not LMT!) this technology for some time. Last demo I saw was real sorry. Not ready for primetime, anytime!

KFung 01-11-2001 08:59 PM

Noah,

The expansion of the image is done by the screen, that's why a long thin image is inputed to the bottom of the screen.

Markm,

I agree with you, one of those articles mentioned the difficulty they had with getting thin layers of plastic for the screens. Resolution was less than VGA. http://www.avsforum.com/ubb/frown.gif

Regards,

Kam Fung


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