3D(?) Laser Imagery

alpha_wolf

I have seen on some occasions in the past, that lasers were used to create a simple image (actually just a relatively simple shape of light) in real-time. It appears as if the image is 3D, although that may be an illusion. I hope you understand what I mean, because I'm not sure I could explain any better...

I would like to know how that works, or at least how is it called (so I can do a search). Is there a screen of some sort, on which the image forms? If not, how is the image created?

Thanks.

pallidin

Might you be talking about a hologram?

chroot

How about some links?

http://hyperphysics.phy-astr.gsu.edu.../holog.html#c1

http://www.holo.com/holo//book/book.html

http://www.holophile.com/history.htm

- Warren

alpha_wolf

No, I'm not talking about holograms, at least not with the meaning suggested by Warren's links. I'm talking about the trick they sometimes do in laser light shows. I haven't seen any first hand, only on tv, so I'm not entirely sure if they are what they appear to be. But from the tv footage it seems as if the resulting image is floating in mid-air. Although perhaps there is some screen or something, which is hard to notice for one reason or another..

chroot

I think you mean the laser shows where a 2D (not 3D) image is drawn by steering a laser's beam around with a movable mirror. Due to the human visual system's persistence of vision, the lines seem to be steady when drawn fast enough. In reality, the beam is just being scanned around rapidly in the desired shapes.

- Warren

alpha_wolf

Well, I have seen one or two cases where the image appeared to be 3D, but as I wrote earlier, that may have been an illusion. Could you tell me where I can find more info on this, or at least what is its offical name (so I could search for it on my own)? Thanks.

alpha_wolf

One image is worth a thousand words, or so they say:
http://www.lobo.de/html/event/images/show1.jpg

What I want to know is how is that face image formed? It seems too sharp and too undistorted for it to be on a smoke surface, and as far as I can tell, the laser projector is behind the image, so there doesn't appear to be any screen there.. So how does it work then?

LURCH

This is only a guess, but I would assume that the bright, solid-looking lines that appear to have a definite three-dimensional location within the fog are the spot where two lasers crossed one another. Although the laser in itself forms only a single line, and scattering of the beam can only form a plane, the intersection of of two beams can be given a three-dimensional coordinate. If that is how the effect was achieved, then I think that does make it, technically, a "hologram". At least, if I understand holography correctly.

brentd49

Has there been any pratical application developed for holograms, and if so what are they? Would it be conceivably possible to develop 3D displays (or even 2D displays) using holography which would have a quality at least useful enough to be worth it (i.e. not tv-quality, but at least the outline-of-an-object-quality)?

chroot

Holography actually has many practical uses. One that particularly interests me is using a 3D optical medium for computer information storage, using holography as a way to address individual slices of the medium.

- Warren

alpha_wolf

Yes, that is currently being developed, and I'm looking forward to the day it becomes publically available. In the mean time, could someone please confirm Lurch's explanation (or if it's not correct, offer the correct one)?

pallidin

I think it could be assumed that this is technical, but not privaledged info. Perhaps you could go to their web site email address and ask how it is done.

salamander

I've seen a 3D screen in a popular science magazine. Basicly it was continously projecting slices of the image on a rapidly rotating mirror in a glass ball... pretty simple technique. The smallest one was $30 000, and I doubt there are many 3D DVDs in the market... compared to a hologram of the same size that isn't too expensive though. Can't remember if they were called something special or just "3D Screens".

Cheers.