"Fishtank" 3-D display

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.