# Info about how holographic projection works?May 18, 2009 11:36 AM   Subscribe

This is a bit of a lazyweb question, but I'm looking for information about holographic projection for some research I'm doing. I just need to figure out the levels of feasibility for some ideas that I am putting together and my Google searches / limited starting knowledge about the subject aren't giving me the quick answers I need.

Without going too in-depth, I'm wondering if any technology exists that could run off solar power to create what would essentially be "light sculptures".

- Is "holographic projection" really what I'm talking about? I'm thinking about the ability to project a 3-d looking form into a space (i.e. without needing to reflect on a screen or some such thing).

- What is the equipment required to accomplish such a thing? Ideally, what is the MINIMUM amount of equipment required?

- What are the effects of sunlight on such a thing? Does it look different from day to night?

I'm wondering if lasers aren't also something to look at, although I'm hoping to minimize the amount of infrastructure involved. In my perfect world, the contraption would, powered by solar energy, project a 3D-looking image in the air.

This is all purely theoretical at the moment, so any ideas about how this would be best accomplished are welcome, regardless of costs.
posted by stefnet to Technology (5 answers total)

Here is how most "holographic projections" are done: Pepper's Ghost. Which would need to be behind a plate of glass. There may be something else out there, but that's the famous one.
posted by jrishel at 12:29 PM on May 18, 2009

This page of information about systems using volumetric displays of one sort of another - might be useful. You can make a "3d image" using a projection against a curved reflector or a matrix of pixels on a display which is turned on a vertical axis using a motor for example.
posted by rongorongo at 1:22 PM on May 18, 2009

Best answer: I'm thinking about the ability to project a 3-d looking form into a space (i.e. without needing to reflect on a screen or some such thing).

Solar powered or not, no one knows how to do that. There isn't even a theoretical basis for such a thing that I've ever heard of.

The closest thing I've heard of involves a rotating frosted helix (of glass or plastic). It spins at 1800 RPM or faster. Lasers beneath it illuminate places on it with timing coordinated so that the place on the helix they strike is at the proper Z position. But that's just a concept; I don't think anyone's even managed to make that work. And even if it did work, it wouldn't look very good -- a whole bunch of glowing dots inside a cloudy cylinder.
posted by Chocolate Pickle at 1:29 PM on May 18, 2009

Best answer: The tech you're looking for doesn't really exist (it is difficult to convince light to spontaneously change direction in mid-air) so I think you would have to fall back to trying to create the *illusion* of something existing in space using glass/mirror/light trickery.

This sort of thing is quite cool, but to create a "light sculpture" the size of a person would require, well, excavating a pit the size of several rooms and then lining it with a perfect parabolic mirror.
posted by so_necessary at 2:22 PM on May 18, 2009

Two parabolic mirrors, because ceiling of the pit has to be a mirror, too!
posted by Chocolate Pickle at 4:33 PM on May 18, 2009

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