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So I just realised that 3d hologram fan projectors are now a thing, and the quality looks quite good (search Ashata 3d hologram fan projector). However, an inherent problem with them is that the image must be viewed at a perpendicular angle to the fan for the image to be visible, meaning they can only be viewed from one side like a tv or projector screen.

I was wondering, theoretically, if one was placed at the bottom of a sufficiently sized mirascope, would this create a hologram that could be viewed from all angles?

Potential problems that come to mind:

  • would the lack of a tangible 3d surface within the mirascope mean the effect isnt created?

  • would the vertical direction of the LED beams from the fan mean light isnt sufficiently dispersed within the mirascope chamber to create a full image above?

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The "hologram fan projector" is badly misnamed, except for the "fan" part. There are no holograms involved, just a rapidly spinning string of LED lights that turn on and off, taking advantage of the relatively slow image decay in your eye to produce the illusion of a continuous,flat image. It's a fun trick, but optically not different from an image projected onto a flat screen.

I'm not sure how fast the "fan" spins, but probably around 15 to 30 revolutions per second. It it spun, say, 100 times faster (dangerous!) and were jiggled up and down along its axis at around 30 times per second, and the LEDs were turned on and off at appropriate times 100 times faster, it would be possible to provide the illusion of a fully 3-dimensional image filling the space within which the "fan" spins.

Alternatively, the "fan" needn't be jiggled, but an image of the spinning fan could be jiggled by viewing it in an oscillating mirror. That would be safer perhaps, but the spinning would still need to be ~100 times faster than it is now.

If you have one of these fan projectors, you could look at it in a small mirror and jiggle the mirror rapidly to see what it does.

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