An idea for a holograph

[Jackissimus]

I was watching the first Star Wars, the scene with "Help me Obi Wan Kenobi ...", and I thought:
Wouldn't it be possible to create a 3D holograph by exciting the nitrogen molecules in the air to shine blue, similar to a fluorescent lamp? The idea is to focus multiple sources of electromagnetic radiation into each voxel of the 3D image. And when the low energy photons meet in the voxel, they would together produce just the right amount of energy to excite the nitrogen. I am thinking something similar to how Two-photon Excitation Microscopy works, maybe even using the same femtosecond laser technology. What do you think?

 

[berkeman]

Sounds a bit like optical-optical double resonance. Have you encountered that yet in your searching?

 

[Jackissimus]

Nope.

 

[sophiecentaur]

to create a 3D holograph by exciting the nitrogen molecules in the air to shine blue, similar to a fluorescent lamp?

A true hologram is a diffraction pattern and it relies on the parts of the pattern all being in stable positions so that an incoming coherent wave will re-form the pattern of the original object. Gas atoms will have a range of velocities and positions and won't cause formation of a coherent image.

You seem to be suggesting a method (not holographic) of exciting all atoms in each 'pixel' in a 3D volume. What you would see would (I think) be a set of bright pixels corresponding to parts of the surface of the original object in a 3D pattern. The problem would be that layers 'behind ' other layers would still be visible. Very confusing. To deal with that, the image processing would have to turn off (blank) bright pixels in directions behind a nearer object.

I guess the processing could make the system work for an observer viewing from just one particular direction.

But Never Say Never. There have been some very whacky display technologies which 'worked' tolerably well in the past. Browse the enormous list of patents for TV displays.