i was watching a movie the other day and in the movie they had a sort of display that seemed to work on thin air. below is a short description of how that may be achieved using gamma radiation.
using a an array of leds (the ones described on this site which emit gamma radiation using americium) which are used to emit the radiation which is used to create the display. the leds would in theory have a change in amperage supplied to the leds to change the distance at which the radiation reaches. using this method one may possibly irradiate a specific distance first using a given amperage, and use the array of leds to turn on or off radiation at this given distance. you would then in theory use a line pattern created by the array of leds (similar to the line pattern of a crt) from say left to right, top to bottom, with this combination to create an image using the radiation.
the area irradiated would in theory require ambient light to bend at that location, which is kind of what the gamma bubble does. it seems to irradiate a given area of space (say air) with a given wavelength of gamma radiation. this in turn changes the amount of energy in each area in the said space which seems to have the effect of diffusing ambient light.
so using this method would do the same for specific groups of atoms, at specific distances, in a specific order thus diffusing the light at those locations.
now i am not able to test this my self so there is little i can do do develop it more at this time.
as posted before i believe i have observed gamma radiation that at specific wavelengths is not only visible, but different colours. the problem from what i have observed using this version of a gamma emitter is the light does not cause the diffusion of light in the irradiated area, travels much further distances, and may be a bit more difficult with out more information to use as a colour source.
anyhow i think with the above someone who had the legal right to test the leds i mentioned could text the different wavelengths (possibly try a combination of different voltages or metals in the alloy which makes up the leds) to test these theories and develop a working model.
if you do let me know i would love to see it.