I've been thinking about Chuck's question, basically what I meant by non-laser-produced holograms, and I admit it's hard to describe my idea. That's probably because it's a b.s. idea. But here goes: There are filters, I assume grid-like, that can eliminate most wavelengths of light. If you could put together one that eliminated all but one wavelength, would that one wavelength work like a laser for the purpose of creating a hologram? I think holograms are possible because the laser illuminating the target emits just one frequency of light. When that light hits the target and bounces back to the film, the waveforms from interfering light bouncing back from various objects are preserved on the film. When a laser shines on the developed film, those overlapping waveforms are reconstituted and you see the object that was photographed in 3D. The fact that the laser is an extremely powerful pulse of light has nothing to do with this process; it's the single-wavelength property that is important. My idea is, what if you were to place a piece of photographic film in a shallow box, with the filter in front of the film, in ordinary daylight. Would you get the same effect because only waveform was penetrating the filter? Of course, to actually see the hologram (assuming you really could make one that way), I assume you'd need to illuminate the film with a laser. Thanks, Joe