HN Theater @HNTheaterMonth

Like these but less plasma? https://youtu.be/AoWi10YVmfE

My favorite part of this is looking at all the toasted skin on the fingertips in the video.

Using the term thin air is misleading IMO.

I saw a slightly different version of this a few years ago [1]. It basically used pulsed laser to create plasma at certain x,y,z without any additional reflective medium added to the environment. However it's crazy loud [2].

From the Nature paper [3] it seems to work on similar principles with the drawback that you need "light scattering (or absorbing and generating) surfaces" instead of free air. In other words you still need some medium for projection/reflection, like a smoke cloud for example:

"it is unlikely that the display would function outdoors without an enclosure unless particles were much more strongly confined or steps were taken to refresh trapped particles regularly"

[1] https://www.youtube.com/watch?v=AoWi10YVmfE

[2] https://www.youtube.com/watch?v=ZeqIZyUMDP4

[3] http://www.nature.com.https.sci-hub.hk/articles/nature25176

⬐ Florin_Andrei

Wow. If you try to do it on a large scale it would be somewhat dangerous too, I suspect.

⬐ logfromblammo

Article mentioned that other volumetric displays could cut off your fingers if you put your hand inside the volume, but heavily features use of fingers in the pictures to show scale.

This only requires enough power to push a tiny speck of dust around.

If you had a precise enough means of determining the position of a particle, and a precise enough means of painting it with visible light, you could rely on Brownian motion to trace out your image. You project the color and intensity of whatever voxel the particle happens to be in at that moment, and the dust scatters that light everywhere.

But if you can force the particle to trace out a specific path instead of a random one, you can make it walk through all the voxels in sequence, and paint your whole volume reliably.

The problems with scaling up are controlling multiple particles at once without making any of them occlude the others from the perspective of the painter lights and pusher lasers. One speck can only travel through so many voxels in the time required to paint one frame. And the more specks you have, the more likely it is that one that is supposed to display transparent will be occluding one that is supposed to be colored. The image would get "foggy".

An example of "tangible interaction" is pressing this checkbox in this video:

https://www.youtube.com/watch?t=100&v=AoWi10YVmfE

In terms of what the projection feels like, this article explains that to some people the laser feels like sandpaper, and to some people it feels like a static shock:

http://www.popsci.com/secret-interactive-holograms-plasma-an...

Here's the YouTube link with the demo: https://www.youtube.com/watch?t=63&v=AoWi10YVmfE

Someday we may have the displays we see in the movies at this rate.

⬐ trhway

beside the images functionality, i wonder whether it can be used to precisely "herd" say a cloud of deuterium ions to get something like microfusion

⬐ kansface

A similar thing does exist and is actively used: https://en.wikipedia.org/wiki/Optical_tweezers