4 ms·

I've seen this in operation and am acquainted with the researchers. I may be able to attempt to answer some questions about it.

by andars 9y ago

iliis 9y ago
Awesome achievement! This really looks like a viable way of true floating 3D-images. Can you levitate multiple particles at the same time? How fast are they moving? How sensitivie is it to disturbances in the air?
- snr 9y ago
  I'm guessing it's very sensitive to air flow since the photon "shells" are literally trapping the particles.
- andars 9y ago
  > Can you levitate multiple particles at the same time? Yes, but their device currently is only capable of levitating a single particle. With the current approach, the device would need one laser for confining each particle. The lasers used for RGB could potentially be multiplexed between particles, but this is less likely to work for the confinement due to the instability of the trap. > How fast are they moving? Pretty slow. All the "big" images (Leia, grad student, etc) are long-exposure. You can see the particle moving in real-time at about 0:50. In the videos, you can see the device can almost do real-time persistence of vision for volumes substantially smaller than a fingertip. > How sensitive is it to disturbances in the air? As I mentioned above, the confinement is weak and the trap is pretty unstable. Its possible that they have improved the longevity of the trap in the last few months, but when doing long-exposure the device is surrounded by a heavy cloth barrier to block both external light and air movement.
snr 9y ago
How does this compare with the plasma dots approach? https://www.popsci.com/secret-interactive-holograms-plasma-and-femtosecond-laser https://www.popsci.com/secret-interactive-holograms-plasma-a... (Thanks @iliis for posting about this research)
- andars 9y ago
  I'm not very familiar with the plasma dots approach, but from a cursory look it appears that it is not capable of RGB. On the other hand, there is nothing that can fall out of confinement so the display is probably more stable. That page says the femtosecond plasma display is pretty safe. This display was - and I believe still is, though I could be wrong - using a UV laser for confinement, which is sorta scary.
starpilot 9y ago
Where does the cellulose come from? Is it just ambient particles or are they emitted from the machine? Where does it go?
- andars 9y ago
  The cellulose comes from the black liquor on a spoon (see 0:46 in the video). The put the spoon at the focus of the laser and with luck some particles get confined. After the trap is lost, the particle just sort of drifts away in the air, since they are only tens of microns.
panic 9y ago
Cool stuff! I'm curious what limitations there are on how fast the particle can move. Is it theoretically possible to move a single particle fast enough to render complex shapes in real time, or will you need many particles for that?
klintcho 9y ago
Would it be possible to suspend these kinds of particles using a standing wave of ultrasound ? Perhaps something similar to https://www.researchgate.net/publication/265401333_Cell_and_Particle_Manipulation_in_an_ultrasound_standing_wave_trap https://www.researchgate.net/publication/265401333_Cell_and_... and then project the laser on them.
- andars 9y ago
  Sorry, I'm not qualified to give a good answer. I would guess that the relatively long wavelength of ultrasound could potentially cause resolution issues.
  - kakarot 9y ago
    Not only resolution issues, but accuracy issues as well. I doubt ultrasound can provide the same fidelity as a highly-tuned laser high-frequency laser beam when it comes to keeping something in one place.
    - klintcho 9y ago
      Thanks for both your answers. Though I was also thinking perhaps you could just suspend the particles in mid-air, and use the movable prism in a laser projector to actually "render" the projection (thus not needing to move them at at a high frame rate or at all). However I guess, you probably do need to move the particles as well to be able to make it a 3D volumetric shape in space (seen from all angles etc).
marshray 9y ago
How powerful are the lasers? What kind of safety equipment is required to view it?

I've seen this in operation and am acquainted with the researchers. I may be able to attempt to answer some questions about it.

by andars 9y ago

I've seen this in operation and am acquainted with the researchers. I may be able to attempt to answer some questions about it.

iliis 9y ago

Awesome achievement! This really looks like a viable way of true floating 3D-images. Can you levitate multiple particles at the same time? How fast are they moving? How sensitivie is it to disturbances in the air?

snr 9y ago
I'm guessing it's very sensitive to air flow since the photon "shells" are literally trapping the particles.
andars 9y ago
> Can you levitate multiple particles at the same time? Yes, but their device currently is only capable of levitating a single particle. With the current approach, the device would need one laser for confining each particle. The lasers used for RGB could potentially be multiplexed between particles, but this is less likely to work for the confinement due to the instability of the trap. > How fast are they moving? Pretty slow. All the "big" images (Leia, grad student, etc) are long-exposure. You can see the particle moving in real-time at about 0:50. In the videos, you can see the device can almost do real-time persistence of vision for volumes substantially smaller than a fingertip. > How sensitive is it to disturbances in the air? As I mentioned above, the confinement is weak and the trap is pretty unstable. Its possible that they have improved the longevity of the trap in the last few months, but when doing long-exposure the device is surrounded by a heavy cloth barrier to block both external light and air movement.

snr 9y ago

How does this compare with the plasma dots approach? https://www.popsci.com/secret-interactive-holograms-plasma-and-femtosecond-laser https://www.popsci.com/secret-interactive-holograms-plasma-a... (Thanks @iliis for posting about this research)

andars 9y ago
I'm not very familiar with the plasma dots approach, but from a cursory look it appears that it is not capable of RGB. On the other hand, there is nothing that can fall out of confinement so the display is probably more stable. That page says the femtosecond plasma display is pretty safe. This display was - and I believe still is, though I could be wrong - using a UV laser for confinement, which is sorta scary.

starpilot 9y ago

Where does the cellulose come from? Is it just ambient particles or are they emitted from the machine? Where does it go?

andars 9y ago
The cellulose comes from the black liquor on a spoon (see 0:46 in the video). The put the spoon at the focus of the laser and with luck some particles get confined. After the trap is lost, the particle just sort of drifts away in the air, since they are only tens of microns.

panic 9y ago

Cool stuff! I'm curious what limitations there are on how fast the particle can move. Is it theoretically possible to move a single particle fast enough to render complex shapes in real time, or will you need many particles for that?

klintcho 9y ago

Would it be possible to suspend these kinds of particles using a standing wave of ultrasound ? Perhaps something similar to https://www.researchgate.net/publication/265401333_Cell_and_Particle_Manipulation_in_an_ultrasound_standing_wave_trap https://www.researchgate.net/publication/265401333_Cell_and_... and then project the laser on them.

andars 9y ago
Sorry, I'm not qualified to give a good answer. I would guess that the relatively long wavelength of ultrasound could potentially cause resolution issues.
- kakarot 9y ago
  Not only resolution issues, but accuracy issues as well. I doubt ultrasound can provide the same fidelity as a highly-tuned laser high-frequency laser beam when it comes to keeping something in one place.
  - klintcho 9y ago
    Thanks for both your answers. Though I was also thinking perhaps you could just suspend the particles in mid-air, and use the movable prism in a laser projector to actually "render" the projection (thus not needing to move them at at a high frame rate or at all). However I guess, you probably do need to move the particles as well to be able to make it a 3D volumetric shape in space (seen from all angles etc).

marshray 9y ago

How powerful are the lasers? What kind of safety equipment is required to view it?