Most projection devices depend upon a lens to focus an image upon a surface. The use of a lens requires mechanisms to adjust the distance relationship of the image to be projected to the lens and the lens to the surface on which the projected image appears. This can get very complicated and expensive and requires precision in components. If a point source of light could be developed that was sufficiently small, no lens would be necessary and all surfaces would be in focus and sharp for projection. Even irregular surfaces would give sharp projected images. The problem is to get a light source as close to a point and sufficiently bright to give a good image, but it would solve a lot of problems.
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The limit would be an apperture that allowed only one photon through at a time, but sprayed successive photons at many angles and at a very high rate. It would be possible to compute the maximum sharpness and illumination levels that could be achievable and the number of photons that would be expected to be scattered by the apperture. It would then also be possible to compute the trade-offs that would result from enlarging the apperture. This would provide a basis for understanding some of the required characeristics of the photon source.
A laser could be thought of as a point source of light- not very efficient, but bright. "Laser diodes" are modified Light Emitting Diodes (LEDs). I have a pair of flashlights that give off an intense bluish light from several LEDs; very bright, intense light sources (focused with a parabolic reflector). I don't know if this helps, but they're a very bright, small source of light, perhaps they could be "focused" through a pinhole aperture.I do pinhole photography, the focus is "soft" at best (we're talking f1:300 to f1:1200 here).