Science Buddies: "Ask an Expert"

Hello! I am posting a quote from my posts titled "3D Holographic Projector"

John Dreher wrote:OK. The diagram really helps. That's clever. Can you make a sphere without crossing rays? (Maybe by time division superposition of 2-D circles within the eye's time of persistence?)

As to apparatus, first let me emphasize that I have NO expertise in optics etc. But what occurred to me was a standard video projector, like those used in projection TV's or, even better, the units used to project images for lectures and other presentations that plug directly into a PC as a remote monitor screen. These can be focused for variable screen distances. If the focus range includes "infinity", i.e. more than 10 m or so, the rays illuminating a pixel on the screen will become parallel effectively, if you see what I mean If the focus range is not adequate, you might need an external lens.

You might want to search for a patent covering this idea.

My question is what did he mean by "Maybe by time division superposition of 2-D circles within the eye's time of persistence?"

Would be extremely grateful if someone shed me some light on this
For more details regarding this please visit https://www.sciencebuddies.org/science- ... 29&t=11902

Please I'm having a problem
Quickly awaiting replies

I'm back. Sorry for the delay. What I meant by "time division superposition of 2-D circles within the eye's time of persistence" was to build up the illusion of a 3-D image from a series of 2-D slices through the 3- D image, with the slices created one after the other in time with the interval between the images in the series so short that the mind is fooled into seeing the time series as one single image. This phenomenon is often called the persistence of vision. This is just what allows a motion picture appear to move even though the individual frames of the movie are static images. Look this term up in Wikipedia for more information. You could even get moving 3-D images using even faster 2-D image creation, just as the "1-D" image produced by a CRT display (as in older TV sets) is perceived as a moving 2-D image by moving the electron beam from pixel to pixel at ~MHz rates.

Thank you for your reply!
Yes the same thought did come exactly to my mind. Your suggestion for using POV is a very nice idea! Only need to gather apparatus, school's opening tomorrow.

Glad to help.