does there exist some material that is totally transparent - yet can serve as rear projection screen?
something along the lines of transparent holographic rear projection foils on glass/PVC - but these are apparently not totally transparent
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- $\begingroup$ This question is similar to: Light activated transparency. If you believe it’s different, please edit the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem. $\endgroup$Solar Mike– Solar Mike ♦2025-01-13 20:58:01 +00:00Commented Jan 13 at 20:58
- $\begingroup$ This is looks like a fairly different question to me. $\endgroup$Demis– Demis2025-01-13 22:18:59 +00:00Commented Jan 13 at 22:18
- $\begingroup$ air is transparent... can you see anything projected on it? $\endgroup$jsotola– jsotola2025-01-14 01:33:00 +00:00Commented Jan 14 at 1:33
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2 Answers
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If you are projecting light from the back, with the intention of the user seeing an image on the “screen”, then it can not be completely transparent.
If the material is completely transparent, then the projection will go straight through the screen and not interact with it at all. A “completely transparent” screen is the same as not having a screen at all, if I’m understanding your question correctly. In this case, the only way for your users to see the image you’re trying to project is to shoot the projection directly into their eyes.
A rear projection typically wants the projected light to hit the screen in a linear Ray between the projector and the screen ( from the Back). But on the front side of the screen, the designers actually want the light to go in many directions, to give the viewer many angles at which they can see the image on the screen. So the screen needs to be something like “frosted glass” or “matte” finish to scatter the rear-projected light into many angles on the front of the screen. (I am sure designers have much more sophisticated methods than just a matte surface though.)
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As explained by @Demis, a totally transparent screen cannot refract or reflect light to the eye of the observer. It will pass through unaffected - apart maybe for a slight offset due to the double refraction. This is basic physics.
It is possible to project onto a water curtain or "fog screen". Here a continuously falling spray or mist of fine water droplets will cause the incident light to be reflected and refracted over a wide area. This will result in the loss of of lot of light so more powerful projectors would be required to compensate.
A Google image search for "water mist projection screen" will get you started.
