What's the technology called for those plastic sheets with the refracting grooves in them to see multiple imgs?

It's flat, like paper, but with a layer of plastic over top of it that has grooves into it that refracts the image printed on the paper. You used to get them in cereal/crackerjack boxes, or printed on a child's plastic ruler, or sometimes even the cover of a book would have them. Depending on the angle that you hold them, you see different images. You could tip them back and forth to produce a little 5 or 6 frame animation. Or some of them even let you see some basic 3D stereoscopic images. You don't need to wear 3D glasses or anything, it's just a flat thing.





What's that technology called? I'm trying to find info about them and I don't know what they're called. Is there a company that will make them for me?What's the technology called for those plastic sheets with the refracting grooves in them to see multiple imgs?
It's called autostereoscopy. The grooved plastic is either a lenticular lens or parallax barrierWhat's the technology called for those plastic sheets with the refracting grooves in them to see multiple imgs?
You may be talking about a Fresnel lens which is flat but provides magnification. It consists of grooves in the plastic. You can see odd optical things when you bend it or look at it at an angle.





You may also be talking about a ';polarizing'; filter which physically blocks some of the light waves and allows other light waves to pass thru. The ';grooves'; are too small to see.





I suppose you could have a polarized Fresnel lens.
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