[HN Gopher] Femtosecond lasers create 3D midair plasma displays ...
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Femtosecond lasers create 3D midair plasma displays you can touch
Author : jagged-chisel
Score : 165 points
Date : 2024-05-14 16:10 UTC (6 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| jagged-chisel wrote:
| This technology came up recently in conversation so I searched
| the web to see what became of it. All I can find are articles
| dating from summer 2015 and nothing of substance after that.
|
| I'm sure we can all come up with some reasons this wouldn't be
| practical in many situations, but the tech seemed promising. Do
| any of you have knowledge of what happened here? Was it smoke and
| mirrors? Just really not practical? I would really like to read
| some details about why this seems to have vanished.
| PaulHoule wrote:
| Go into a lab in the first floor of the physics building at my
| Uni and you are likely to find a femtosecond laser inside which
| sprawls over an optical bench which takes up most of the room.
| At the heart of it is a fiber laser that costs about $250,000
| but they usually have added a lot of stuff to it.
|
| A femtosecond laser for medical use is about $400,000
|
| https://crstoday.com/articles/2014-sep/pricing-the-laser-cat...
|
| which is one reason you might not see this become widespread.
| jandrese wrote:
| Ironically that seems promising. This could just be an
| engineering problem where the only people making the required
| laser equipment are only making lab/medical grade gear with
| enormous markups. It's possible someone comes up with a
| practical to manufacture solid state version that unlocks
| these displays for the masses.
|
| There is one consideration however where one failure mode for
| this device includes a situation where the processing locks
| up and leaves the laser pointed at a single spot
| continuously, burning a hole and possibly starting a fire.
| yetihehe wrote:
| > where the processing locks up and leaves the laser
| pointed at a single spot continuously, burning a hole and
| possibly starting a fire.
|
| Already solved for 3d-printers locking up and starting a
| fire.
| PaulHoule wrote:
| Lasers used for laser light shows already have interlocks
| that will stop the laser if the mirror stops moving.
|
| My understanding is that femtosecond lasers have some parts
| that are physically large because they use prisms,
| diffraction gratings, and such, to spread out a pulse so
| the laser can effectively amplify it and then recompress
| the pulse to use it.
|
| See
|
| https://en.wikipedia.org/wiki/Pulsed_energy_projectile
|
| note a workable laser "gun" could plausibly be "set to
| stun" because if the energy of a pulse sparks the air near
| your skin or clothing, the plasma absorbs almost all the
| energy causing a plasma explosion which can knock you down
| plus cause severe pain from an electromagnetic pulse.
| emchammer wrote:
| The pulses are not entrained to software. They are inherent
| to the laser's design, such as with Q-switching.
| vlovich123 wrote:
| I think ops point still holds - actively modulated q
| switches could still have a failure that pushes the laser
| outside the safety parameters, no? I don't think OP was
| necessarily suggesting a software failure.
| alt0_ wrote:
| I'm incredibly curious as to what that even looks like. Where
| do you study? Can you give us a photo?
| PaulHoule wrote:
| See
|
| https://www.oist.jp/image/researchers-femtosecond-
| spectrosco...
|
| or
|
| https://www.mp.aau.dk/research/laboratories/physics-
| lab/shor...
|
| or
|
| https://hajim.rochester.edu/optics/sites/guo/virtual-
| lab.htm...
| zonkerdonker wrote:
| Seems like the tech is still likely alive and kicking in the
| military space:
| https://patents.google.com/patent/US20200041236A1/
|
| US Navy submitted a patent in 2018 for a jet-mounted plasma
| decoy projector, I'm sure they have many more applications that
| I wasn't able to find as well
| JumpCrisscross wrote:
| > _the tech is still likely alive and kicking in the military
| space_
|
| I mean, it's a field that burns things that wander into it.
| I'm genuinely blown away this was considered for a display
| technology. It's closer to the risk profile of fireworks than
| an OLED.
| chris_va wrote:
| Pfft, this is just a bunch of hot air.
|
| ... /s
| ffhhj wrote:
| I remember IO2 Heliodisplay from around 2007. Now their site
| seems to be dead.
|
| > This holographic-style display works by projecting a 2D image
| onto a cloud of microscopic droplets (probably water, although
| this isn't confirmed)
|
| https://www.techpowerup.com/forums/threads/io2-launches-%E2%...
| Nursie wrote:
| I followed them for ages, such cool tech for the early 00s when
| they first publicised it. But it never seemed to have gone
| anywhere.
|
| They were very cagey at first about the fact it used water
| vapour because they didn't want people to think it was just
| projection onto a vapour screen when they had some sort of
| directed laser tech. It still needed the water though!
|
| If I were to guess why it didn't reach any sort of momentum, I
| reckon they couldn't control the costs or get the brightness
| good enough. But that's really speculation.
| zoklet-enjoyer wrote:
| UFOs
| Log_out_ wrote:
| Now print circuitry mid air and energize..
| dmbche wrote:
| Very cool!
|
| How energy efficient could it theoretically be? Is it somewhat
| relatable to touchscreens, or are we talking thousands of times
| more power per pixel per second?
| lainga wrote:
| Weren't these things ear-splittingly loud from the constant
| formation of plasma balls in midair? That's what I recall from a
| demonstration In The Day
| mey wrote:
| Looking into the plasma/laser paper and it mentions 77.2 dB at
| an insanely close 22mm distance. Background was 55.7.
| http://arxiv.org/pdf/1506.06668v1 Page 9.
|
| It sounds (hah) like it wouldn't be pleasant if you have your
| head near a full display in operation, especially since the
| noise scales with the resolution/brightness. It would be
| interesting to see how quickly the noise drops off over
| distance. You are looking at something between a home sound
| system, vacuum cleaner, or highway traffic at that volume
| level. Tolerable but not pleasant.
| Filligree wrote:
| I wonder if it could be modulated to function as a sound
| system?
| ben_w wrote:
| Yes.
|
| You may enjoy the similar use of Tesla coils:
| https://youtu.be/rd3bH_xNYYQ?si=TXO_kA0PZ6YkUZyt
| doublerabbit wrote:
| Personally I'm more the floppy drive fan.
|
| https://m.youtube.com/watch?v=8fh1CIupVXU
|
| But Tesla coils are cool, as are van de graaff
| generators.
| tflol wrote:
| > The researchers found that a pulse duration that minuscule
| doesn't result in any appreciable skin damage unless the laser is
| firing at that same spot at one shot per millisecond for a
| duration of 2,000 milliseconds
|
| Haha so if this thing is misconfigured badly enough it can just
| melt you
| golergka wrote:
| How much does an 0-day cost for a device that can literally
| kill?
| kjkjadksj wrote:
| Ask an automaker or an airline
| moffkalast wrote:
| Boeing's hitman could not be reached for comment.
| glitchc wrote:
| I hear they will pay a visit though if you hashtag
| "whistleblower" and "Boeing"
| solardev wrote:
| Do they just show up and remove all your door hinges?
| vlovich123 wrote:
| That's very awkward wording. Is it saying a 1ms pulse every 2s?
| throwaway11460 wrote:
| I understand it as one pulse (shorter than a ms) each ms for
| 2 seconds.
| itishappy wrote:
| fs pulse duration, 1ms repetition rate, 2s run duration
| itishappy wrote:
| It'll engrave you. The spot size is small and the material
| removal rate is low.
|
| Still not fun, but it's not gonna take a finger.
| yreg wrote:
| Sounds like a promising topic for an Electroboom video.
| jpgvm wrote:
| There are many display technologies that just didn't make it to
| mass production.
|
| A favourite of mine is Field Emission Display technology. However
| they are largely irrelevant now because OLED essentially fill the
| same role.
| worldsayshi wrote:
| Mine is transreflective LCD. I just really want to be able to
| work with my laptop in the sun.
|
| https://en.wikipedia.org/wiki/Transflective_liquid-crystal_d...
|
| Here it's used on the Adam Tablet that never took off:
| https://www.youtube.com/watch?v=pGUKHDBoTEc
| Woovie wrote:
| LTT just made a video about a modern display that is like
| this tech https://www.youtube.com/watch?v=c0TcGjzKbag
| worldsayshi wrote:
| Interesting! Although going for _no_ backlight seem to make
| it about as impractical indoors as regular displays are
| outdoors?
| cycomanic wrote:
| Hi had an Adam, the idea (and display) was pretty cool, but
| the build quality and software was not that great. Eink
| really has taken over that niche though, so not sure I really
| miss those displays.
| worldsayshi wrote:
| Yeah it seems that TLCD never really got a chance to get
| developed properly.
|
| And Eink seem to me to have a lot of other clear drawbacks
| which makes it impractical for regular work use cases.
| tootie wrote:
| We played with lenticular displays and they are very good and
| very safe. But like it's just not that useful to have a 3d
| display. A 2d screen is perfectly good at conveying the same
| information.
| cyberax wrote:
| I have a slight eye damage in one eye from working with lasers
| that were just a bit outside the safe limits. And I realized that
| only years after getting it.
|
| So the last thing I want, is to be near unconfined lasers
| powerful enough to ionize the air.
| CodeArtisan wrote:
| How did you realized you had eye damage?
| BikiniPrince wrote:
| check engine light in the upper left hand corner of his
| vision.
| utensil4778 wrote:
| Typically you'll notice a persistent black spot in your
| vision. Particularly if you're looking at a bright field like
| a blank white page on your monitor.
| jessriedel wrote:
| Cite? My vague understanding of how vision works is that
| your brain will tend to interpolate over missing data
| rather than perceive it as black. So you need to actually
| test whether you can discriminate things in the affected
| field of view.
| atomicnumber3 wrote:
| Vision is complicated. Everyone's vision experience is
| slightly different. So different people might notice
| different things.
| __MatrixMan__ wrote:
| This is not a citation, but...
|
| I have this spot in my right eye that resembles dead
| pixels. Just tiny blackness. If I let my eyes try to
| focus on it, it moves with my eyeball, so then they try
| to focus on the new location... ad infinitum. So they
| sort of jitter on a path upwards and to the right. I can
| only see it in certain lighting.
|
| Eye doctor couldn't see anything wrong with the area and
| suggested it might be a floater that got attached and
| would go away on its own within 6mo. That was 4yr ago and
| it's still around. It's not getting worse so it doesn't
| bother me, it just reminds me of the saa from the Wheel
| of Time.
|
| I would have expected interpolation versus vision
| artifacts as well, but apparently that's an "only
| sometimes" thing.
| TrainedMonkey wrote:
| Don't know how OP did it, but I've been tested a couple of
| times at the optometrist by field of view machines*. You
| concentrate on a central point while the machine shows you a
| pictogram in a random location with a random timing. You
| click a button every time you see one.
|
| Note: not an actual name, I don't know how these are called.
| prodias2 wrote:
| I believe the machine you're referring to is called a
| Humphrey visual field analyzer.
|
| https://en.wikipedia.org/wiki/Humphrey_visual_field_analyse
| r
| cyberax wrote:
| If I look at a straight line with the right eye, I see a
| "kink" in it. Grids look like they are warped in near the
| center.
|
| Turns out, that I have a "pinhole" damaged area in the right
| eye's fovea. It's small enough that the brain can
| "interpolate" over it, especially when both eyes can see the
| object.
| CamperBob2 wrote:
| Gee, if only they had thought of this rather obvious point and
| addressed it in the article.
| qwertox wrote:
| I think the same happened to me with LEDs. I have an odd
| feeling that I can't really see a small section somewhere close
| to the center of focus, not directly at it. I remember an odd
| sensation in the eye for days after dealing with a white LED.
| fy20 wrote:
| Are you sure thats not just the blind spot? It's quite big -
| roughly the size of a rubbish bin lid on the other side of a
| bedroom.
|
| Here's how to spot it:
|
| Hold you hands together, with thumbs up, at arms length.
| Close your left eye, and slowly move your right thumb away to
| the right, while looking at your left thumb. At around 6
| inches it will dissapear.
|
| It's kind of hard to notice when my thumb is static, but it's
| more obvious if I wiggle my thumb while doing it.
| istjohn wrote:
| Woah, that's neat!
| qwertox wrote:
| Wow, cool stuff! But no, its _much_ closer to the center,
| and it 's not something I can really spot. I just know that
| it started after I dealt a bit with newly bought "high
| power" leds. Not really high power and I never really
| looked directly into them (them facing at me). It also
| might have been some bright, red ones on breadboards.
| Happened over 10 years ago.
| AdamH12113 wrote:
| Optometrists have cameras that can take pictures of your
| retina and see if there's any obvious damage. You might
| consider getting your eyes checked out.
| jijijijij wrote:
| You may be able to better pin it down along sharp
| contrast lines, maybe moving, or flickering patterns. Eg.
| a black and white grid, stripes, or small checkerboard
| pattern on an LCD screen. And of course isolate eyes for
| these tests.
|
| Your brain can fill in a lot of voids before you notice,
| especially for monotonous areas and static impressions
| (as mentioned the blindspot or the blood vessels on your
| retina are usually "invisible" until you provoke
| awareness through unusual lighting changes, eg. pin light
| from a shallow angle, or defined peripheral accounting
| experiments). You likely won't notice acquired
| "blindspots" looking at a white wall, or chaotic fallen
| leaves on the ground, especially where the other eye
| provides missing information, but at the edges of highly
| predictable patterns, one eye closed at a time, you may
| trick your brain to fuck up, eg. blur or indent otherwise
| clearly defined areas, when it can't decide which color
| to fill. Reading texts with on eye closed may also
| highlight "dancing" letters or distortions around your
| center of vision.
|
| Worth noting, such defects may be caused by progressive
| conditions like retina detachment or even ocular
| melanoma, and the association with laser/light accidents
| may be incidental. If you spot a spot, _do not brush it
| off_ as a limited loss! Have it checked, even with a
| likely attributable cause. You may prevent full blindness
| through medical intervention in case of disease!
|
| Edit: You can see the blood vessels when you look a white
| wall and steadily move a (smartphone) flashlight in and
| out of the field of vision, slowly waving the light next
| to your head, illuminating from "your ears" to the side
| of your nose and consequently your eyes at a shallow
| angle for a moment. This will cause an unusual blood
| vessel shadow meandering through your vision. The blood
| vessels are also very visible during eye examinations
| when the doctor moves the slit lamp around - go check it
| out ;)
|
| Very weird seeing the insides of the very eye seeing, by
| ... well ... seeing.
| solardev wrote:
| Warning: Do not touch laser with remaining hand.
| rolandog wrote:
| > So the last thing I want, is to be near unconfined lasers
| powerful enough to ionize the air.
|
| I wholeheartedly agree. Just thinking about how the
| potentially-unregulated cheaply-manufactured knock-off
| projectors will result in having to wear welding glasses when
| walking around the street to avoid being blinded by the 3D
| advertisements that are being shot at your face...
| colordrops wrote:
| This article is 9 years old. Probably went nowhere because of
| the reason you state.
| bawolff wrote:
| > However, a nanosecond-scale plasma burst still contains a
| significant amount of energy; you don't want to go walking
| through one of these displays, because it will burn you.
|
| Yeah, i think that answers the headline question. Burning people
| is bad.
| jjk166 wrote:
| So will touching a lightbulb, but we have those in abundance in
| the same application. I don't think that adequately answers the
| question.
| bawolff wrote:
| We don't usually have lightbulbs suspended mid-air at human
| height without some sort of protective case.
|
| I guess i assume the point here is to have no protective case
| since the article made such a big deal about touching the
| display.
| jjk166 wrote:
| The overwhelming majority of lights are within human reach
| with no protective casing. There might be a lampshade to
| diffuse the light, and some frame to physically support the
| bulb, but nothing to stop a human hand from reaching in and
| touching it. Hell installing and replacing bulbs is
| typically done with bare hands. Free hanging bulb lights
| used to be quite common in closets and basements.
| twic wrote:
| While we're on the subject, what happened to uBeam?
| dotnet00 wrote:
| Reminds me of the story from a few years ago where the US
| military was looking into scaring people via screaming balls of
| plasma, which gave rise to the joke that the CIA was trying to
| make religious extremists think their god was talking to them
| using the tech.
|
| https://newstarget.com/2018-04-24-u-s-military-creating-non-...
| farkanoid wrote:
| I remember this! I'm glad someone else does too.
| farkanoid wrote:
| I often wonder the same about the technology used in a mysterious
| video that appeared on youtube about 15 years ago titled "Laser
| Induced Plasma Channel".
|
| It appears to be an area denial weapon that uses femtosecond
| lasers to guide electric arcs across a hallway (think a metre-
| long ridiculously straight Taser discharge).
|
| The video had no description and comments on it were never
| answered - it was recently removed by the uploader, but there
| seems to be a reupload on DailyMotion[1] from 9 years ago.
|
| [1] https://www.dailymotion.com/video/x31ovvi
| Animats wrote:
| See-through displays show up in movies so that the viewer can see
| the actors' faces. Not because see-through displays are useful.
| 201984 wrote:
| (2015)
| ErneX wrote:
| (2015)
| max_ wrote:
| If you're interested in that project.
|
| Here is an equally cool project form Voxon Photonics. That you
| can buy today and is also very safe.[0]
|
| [0]: https://voxon.co/
| jcims wrote:
| This page has been around for a while. If you watch the YouTube
| video, you can see the skin on the person's finger get burnt as
| they touch the little tiny plasma balls.
|
| https://youtu.be/AoWi10YVmfE?si=1zzwNba9A1l9Y2ld
| vonzepp wrote:
| This is quite hard to do safely. Generating air breakdown with IR
| femto requires a reasonable amount of fluence. They are probably
| using galvo scanners to shift the beam in xy, but to get the
| required intensity they have to also shift the focal plane. Given
| the distances they are projecting away from the car that NA is
| low meaning they would need a reasonable power. Probably why they
| are running it at 1kHz. Given its 2015 it is probably a ti-
| sapphire at 80fs, galvos and an optotune lens. The reason this
| isn't a thing is that it very hard to make this eye safe.
| jagged-chisel wrote:
| This was supposed to be Ask HN but I didn't realize I was on the
| wrong page for Ask submissions. So the title was changed to
| reflect the article. Anyway, my comment asked the question and we
| got some discussion, so it's all good.
| m3kw9 wrote:
| Until a kid put his face in it for fun
| bilsbie wrote:
| Whatever happened to the idea of sending electricity through air
| with this technology?
|
| One application I heard of in the 90s was a long range taser.
| ForOldHack wrote:
| Que ads.
| RIMR wrote:
| OP forgot to include it in the title, but this is from (2015).
| thesh4d0w wrote:
| Worth calling out this article is from 8 years ago.
| nirav72 wrote:
| With all the recent progress with robotics and 'AI' - I was just
| waiting for progress to be made in hologram tech.
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