A three-dimensional display using a transparent tank of laser dye. Two or more UV laser beams enter from the bottom of the tank. These are steered with optoacoustic or electromechanical modulators. Where the two beams cross, the radiation density is high enough to cause the dye to fluoresce, producing a visible luminous dot. Elsewhere, the dye is transparent. By steering the lasers appropriately, the beam intersection can trace out any arbitrary 3-d shape, and thus make it visible. Persistence of the dye's fluorescence can smooth out any flicker (but will reduce the maximum display rate). Could do a vector-scan approach where the beams scan to arbitrary points, or a raster-scan where one laser is a line source that scans a moving plane in the tank, while the other laser picks a point or points on that plane.

Are there any chemistry ninjas who can comment on the feasibility of a two-level laser dye? I'm imagining a molecule where the fluorescent state is reached via two different energetic states, each one pumped by a different frequency of laser light. Light of both frequencies would be necessary to reach the top state, and thus eliminate fluorescence at points other than the beam intersection.
-- rmutt, Oct 16 2000

3D Technology Laboratories http://www.sfgate.c...6/08/30/MN40582.DTL
Baked! [rmutt, Oct 16 2000, last modified Oct 04 2004]

Pictures of 3D display http://www.3dtl.com/index.html
[rmutt, Oct 16 2000, last modified Oct 04 2004]

You're missing something. He's not talking about fish...He's talking about a fishtank full of the laser-reactive dye.

Shouldn't be too hard, actually; if it takes X amount of power to make the dye fluoresce, make the lasers (X/2) so the intersection gets a total of X, but the other areas only get the lower power laser.
-- StarChaser, Oct 16 2000


PeterSealy: laser dyes are usually toxic, so I wouldn't recommend live fish. StarChaser: I'm not a chem ninja, but I think most dyes are relatively linear, so that X/2 power means X/2 brightness, not dark. It would be great if I'm wrong, though.
-- rmutt, Oct 16 2000


Yeah, I don't think fluorescence has the "threshold" you're relying on. Even if it did, you'd be left with the problem that to reach the desired point, the laser would have to be strong enough to survive the attenuation in the medium, which means it would be significantly brighter near the source, possibly setting off this (hypothetical, probably non-existent) fluorescence threshold.
-- egnor, Oct 22 2000


Chemistry is not my thing, I was looking at it more from a half-assed mechanical view. <grin>
-- StarChaser, Oct 22 2000


Cool.

Do you know how 3DTL get around the problems we're discussing above? Is it that we misunderstand the mechanics of fluorescence?
-- egnor, Mar 12 2001, last modified Mar 13 2001


3DTL thing may be old, but I saw it yesterday (3/11/01) at the ACM1 conference in San Jose. Their system works exactly as described, even to the 2-photon chemistry, except that the dye is in a glass or plastic matrix instead of liquid. (They had a bottle of flourescent liquid to show that it would work for that too). They use the vector scan approach.

P.S. Egnor: Look man, the Halfbakery is not the place to diss ideas that might flop!
-- rmutt, Mar 13 2001


Has anyone considered using photonic crystal traps combined with electromgnets to float the "dye" in desired ares? This could be used in a non-flourescing media to arrive at the desired effect? Plus it adds some additional mechanics (for those of us that like that stuff) and would give the guys over at MIT's photonics lab something to do.
-- Reverend D, May 30 2001


This must be somewhat like how 3D polymer printers/rapid prototypers work.
-- bristolz, Oct 29 2002


3D polymer printers work a bit differently. They use a laser to trace out the 2D horizontal slice of the bottom of the object, then move the platform just below the liquid line down a bit, trace the next slice, move it down, trace the next slice, etc.

The 3D display analogy would be a bit like the flapping display, or even better, the rotating 3D displays that are already baked.
-- imagin8or, Jun 24 2003



random, halfbakery