I don't understand the distinction. You said it's not a 3d display, then described a 3d display technology.
That's like saying a CRT doesn't display a picture because it energizes pixels only one at a time.
That's like saying a CRT doesn't display a picture because it energizes pixels only one at a time.
You can also make things like holographic lenses [1].
And, "display" doesn't seem right. If you recorded a still image, it's a (literal) record of the light field of a scene that lets you view the scene in 3d, like a magnifying glass functioning from all perspectives [2]. You do get the "display" of a 3d scene out of it, when used that way.
Fun fact, you can make your own at home with gelatin, some photo chemicals [3], a laser, and a ludicrously stable table. DIY hologram is going to be one of the first things I do when I retire.
[1] Used in HUDs, like in fighter jets. https://en.wikipedia.org/wiki/Holographic_optical_element
[2] https://www.youtube.com/watch?v=iMdvBmePm9U and https://www.youtube.com/shorts/DnjATyPuFFk
I wouldn’t say they “didn’t” take off. They’re gradually acquiring market share.
Its problem seems to be that it was a solution to a problem that was fast disappearing, at the cost of unacceptable tradeoffs.
The Lytro sacrifices a ton of resolution and produces crappy images, in exchange for being able to refocus. And they did that in an age where excellent autofocus was already available.
These days we have cameras with AI models that recognize birds and animals and focus flawlessly almost every single time. And they don't sacrifice any resolution to do it. And they are proper, comfortable cameras rather than a weird stick.
Problem is you can already take a fairly deep focus image (with a stopped down lens) and then fake shallow focus later if you want.....
(I own a similar print, different microscope).
Holograms are cool but it is a finicky technology and speckle makes them visually ugly.
Holography is the display, not the rendering process. It contains, inherently, how the light is focused, so your eyes can refocus on near and far objects within the scene even though it's a static image.
But more to the point, a hologram is less like a computer display and more like a photograph.
It's possible that you haven't actually seen a real hologram. It's quite impressive. The ones I have seen are 3-dimensional objects in the air in front of you, and you can walk around it, typically not the full 360 degrees, but it's just.. there. It's nothing at all like what we normally call a "display".
One can hope we someday have this capability.
It's not exactly like looking through a window, they can do that, but they can render an image in front of the window as well as behind it.
"Screen", sure, that implies 2d. "Display", is a much more general term covering screens, LED readout panels, a shadowbox of physical objects, and more. There are a lot of things that are displays that are 3d already.