Very few people in the comments seem to understand what holography is. A hologram is not a “3D display” that mimics a sci-fi movie or TV show. A hologram is photographic media / display technology that records and transmits phase as well as intensity of incident photons. By capturing all the properties of the electromagnetic field that strikes the film, and re-emitting the same EM wave when stimulated, the hologram ends up being a full “3D picture” because after all, the light that hits your eyes ends up being the same as if you were looking at the actual scene. But that’s a consequence, not the defining property.
"Hologram" is one of those words that has a wide variety of overlapping meanings. You can be a strict prescriptionist about it and insist that a real hologram involves laser light, interference patterns, 3D scene replication, phase preservation etc, but there will always be something that doesn't quite meet your definition that nevertheless is called a "hologram" by large numbers of people, even expert optical scientists:
A digital holographic stereogram prints an array of hogels (holographic pixels); the hogels themselves are holograms, but are mutually incoherent across the plate. When implemented to the highest level, the result is perceptually and behaviorally indistinguishable from an analog hologram.
A rainbow hologram (such as are found on credit cards) has single parallax only - it certainly does not capture all the properties of any particular electromagnetic field. No purity here, it's just a nifty tech for making things look 3D that happens to exploit wave interference. And everyone calls those holograms.
A scratch hologram is, to a first approximation, an extremely coarse version of a rainbow hologram, made by hand by engraving curved grooves in a reflective material. Now we're away from lasers and wave interference, and for this we sacrifice color - but geometrically we are still dealing with directional microreflections on a surface. Hologram? Depends who you ask.
Lenticular holograms use refraction rather than diffraction to achieve essentially the same imaging model as a rainbow hologram, but in a decidedly less finicky way, at the expense of some resolution. The same imaging data could be used to make a lenticular or a rainbow hologram. No lasers, no diffraction. Hologram? Depends who you ask...
My advice, as someone who has worked with holograms for a decade, is to give up. Saying "AKTUALLY Tupac/Abba isn't a hologram" gets old after the 1000th time. In the real world, "hologram" means "intangible optical simulacra", regardless of how it was achieved. If you want more precision than that, you have to specify the actual technology - Denisyuk, rainbow, lenticular, etc...
When someone asks "can you make a hologram of this", you don't lecture them on optical physics. You say "sure, you want the expensive kind or the plastic kind?"
Having also spent a long time in actual holography, I would agree with your assessment generally and your catalog of different "holographic" techniques.
I might quibble with lenticular displays, since they have a name that predates holography.
In the ideal world, a larger umbrella term would have emerged. "Autostereoscopic" describes any display that provides different views without glasses, but that typically suggests discrete views.
"Plenogram" would have been reasonable following Adelson and Bergen's plenoptic function, but that didn't and won't happen.
"Hologram" now basically means a sufficiently advanced three-dimensional display in popular culture. And that even leaves of other real holograms, such as the ones used for non-destructive testing.
Fascinating, but I do wonder if you're not being the pedantic one here. All of these depend on reproducing the phase of a wavefront. Even a traditional hologram fails this purity test - you don't get a full intensity + phase map without taking multiple images with different phase of reference beam.
Yes, it's a tech that can be used to display in 3d, but not sure that's the best categorization choice overall.
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.
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.
2012, commercial availability (failed in 2018 and eaten by Google).
2017, used in scientific settings.
2021, sold commercially to consumers through kickstarter.
2026, multiple companies still sell light field cameras at modest quantities.
I wouldn’t say they “didn’t” take off. They’re gradually acquiring market share.
It's a light field rather than merely 3d, so you can record not only a 3D image of a microscope but also if you look down the hologram's eyepiece you get to see the thing it is focussed on: https://www.youtube.com/watch?v=K-ahG_Q2xRc
A properly constructed light field image can do this, so can a virtual reality headset or other "video game technology" system if it properly models refraction with ray tracing or another method.
"Another method" is doing a lot of heavy lifting there: computational holography is possible, has been for a while, but comparing it to raytracing is an apples-the-fruit to Apples-the-computer comparison.
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.
As a person trained in physics I’d say ray tracing is based on the ray theory of light whereas computational holography is based on the wave theory of light.
A headset only ever renders one viewpoint at a time. A hologram records and re-emits the whole light field all the time., so it is simultaneously viewable from every perspective.
Well, two viewpoints, one for each eye. And it adjusts what it renders when you move around so the effect is similar to a hologram and I'd say, competitive with it. If you are just one person the other views are wasted, and more than one person can share the same VR scene and get their own two viewpoints.
Holograms are cool but it is a finicky technology and speckle makes them visually ugly.
> I don't understand the distinction. You said it's not a 3d display, then described a 3d display technology.
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".
We can imagine a holographic display though. It would look like a window. Not a metaphor of a window, but an actual window. Like, a pane of glass you look through to see a real, physical scene on the other side, indistinguishable (to resolution limits) from the real thing.
"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.
A CRT doesn't display a picture, it produces a dot of photon emission which varies in color, intensity, and position over time across a 2D surface. The picture happens in your mind.
Holograms compete with many other display technologies such as stereograms, VR headsets, as well as volumetric and light field displays. This technology is described as "holographic"
but it looks better than holograms because it uses incoherent light field technology that doesn't have the speckle, plus the pipeline to make content for it doesn't require lasers, special equipment or special skills.
Strictly speaking that's not holography if I understood it correctly. Holography is based on interference created by a surface with a special pattern, and it doesn't require any matter other than the diffractive surface. Whereas here they say they move "particles" (what particles? dust? atoms?). Still pretty cool of course and a thing on its own.
It's "just" an engineering problem at that point though. It works. First it'll be at Disneyland for tens of millions of dollars and then it'll be in Vegas for millions of dollars and then eventually we'll be able to get it at BestBuy for $1,999 in 40 years.
I wanted to pick up doing holography again, but I discovered that Integraf, founded by legend TJ ( https://www.integraf.com/about/tung-h-jeong ), stopped selling the film and supplies.
Much of the supply chain for modern hobbyist holography was sourced out of Russia, and the ongoing wars have made those materials unavailable.
There are some newer processes out there, but there were probably thousands of us that grew up using those HoloKit holography kits distributed by TJ.
You can get holographic film and kits from http://www.litiholo.com. These are not silver halide but are Covestro Bayfol HX photopolymer film which require no post processing.
Wow, they have a laser with a shutter! The Litiholo kit just gives you a basic laser diode, and they don't tell you that you have to let the laser warm up before exposing the hologram. I made so many smeared/blurry holograms before I figured out you have to block the laser, turn it on and warm up, then unblock the laser.
The traditional emulsion had peak sensitivity at 633nm. I don't know much about it otherwise but it was much easier to handle as glass plates rather than film. Russia led the science of this for decades.
Silver halide based holographic plates are like conventional black and white photographic material, only extremely high resolution and very low sensitivity.
That's required because off-axis display holograms have spatial frequencies ranging from about 1200 line pairs per mm for transmission holograms to maybe 5000 for reflection holograms.
Because the grain size is so small, these plates tend to be pretty insensitive to light. That's why they have limited use outside of holography these days.
Other types of emulsions such as dichromated gelatin also exist but are also hard to find. DCG is even less sensitive to light.
In either case, the wavelength the material is sensitive to matters when exposing with a single frequency laser.
Then there are issues about the substrate if the emulsion is on film related to polarization preservation.
I went to a whole art exhibition of holograms as a kid that blew me away, and I've always wondered why holograms are so rare ever since. I had one for a while, the famous one of the microsope with the lens that you can actually look through to see a computer chip inside. There's nothing else like it.
Maybe if you could figure out a digital work flow with digital development method it could really take off. But holograms are analog and hard to deal with.
The price of entry to kick off digital photography was a fraction of a megapixel, the industry really kicked into high gear around VGA resolution which is about 1/3 of a megapixel and it was VERY plausible for the computers of the time to manipulate it, store it, transmit it, display it, edit it, etc.
A very "entry level" not good but maybe enough to kick off an industry digital transmission hologram would be like "hundreds of gigapixels" or at least dozens and thats not realistic for computers of this time. The super cool reflection holograms are much worse, like "many dozens of terapixels" to even begin to play with.
I guess its good news there are still frontiers of computation out there to reach. A lot of people believed progress would cease when computers could do high enough resolution video, and they're mostly correct, progress has halted for the general public. But if we ever get smart phones with low petabyte fast on device storage and display, those could realistically have "star trek" like transmission holograms.
That beings up some interesting issues WRT RF engineering. Shannons law and all that. Even with unimaginably complex compression algos will something like a hand held hologram video conference (similar to sci fi tropes) ever be possible? Maybe 60 PB/s would not be unreasonable. Consider the LHC only generates about 1 PB/s when its running and that takes a rather large distributed system and a lot of electricity. I don't think video conference holograms will be realistic... Strange thought experiment the only way to do a "holographic video conference" with sane data transfer rates and power levels might be to send the other side a LLM prompt and ask for a locally AI generated video hologram. "Here's 1000 jpeg pictures of me as raw data, render a hologram of me saying 'scotty beam me up'"
The display hardware tech would be pretty wild. I think it could be done but it would require a minimum of 1980s nanotechnology hype. Like DLP but using individual atoms not "large" silicon mirrors.
In summary the MVP for digital photography required early 1990s hardware, but the MVP for digital holograms requires a LOT more than 2020s hardware. Maybe in the 2040s, 2100s, who knows.
Me too, in Munich, must have been late 80s. Friend of mine also had "the book" and we dreamt of building our own lab in my basement. Sandbox on tire tube cushions and all.
I suspect, for your typical art nerd, holography is prohibitively expensive and limiting in expressiveness. And for your typical tech nerd, it's also prohibitively expensive and limiting in expressiveness.
Probably true, but I reckon there's surely at least some money to be made for a commercial enterprise if anyone wanted to go big, and nobody has. Get the price down via mass production and automation. Get some holograms into the shops. Sell them in an online store (you can buy holograms online already, but only a few from small operators at high prices, or second-hand). Let people send you their 3D models or 3D scenes and you'll send them a hologram of it. You can even do short animations (there's nothing stopping every new perspective being a different frame!). Have your AI convert people's photos to 3D and then output a hologram of them.
You do need to have a decent point light to shine on it, but you can sell that too. You can even sell a frame that has a clip-on light that's just right[1], although a perfect lighting setup is not required.
>Let people send you their 3D models or 3D scenes and you'll send them a hologram of it.
Oh hey, I have worked in exactly this business (taking people's random 3D models and bullying a rendering pipeline into feeding a digital holographic printer). It's hard, for many reasons. Mainly it's that holograms are expensive in materials, labor, and capital outlay (adding up to several k just for something the size of a piece of paper), and mass production of digital holograms isn't really possible without massive further outlay - writing them is time consuming, and copying them is fraught. It's like being a graphic design / print workshop, except everything is way more fiddly and expensive and nobody wants your product.
Analog holograms are a bit more tractable. But that's even more niche on the consumption end.
It wasn't that prohibitive. When I did it, I had a helium neon laser recovered from an old supermarket scanner, but it can be done with one of those $10 keychain lasers. The chemicals weren't too expensive, but the holographic plates could get pricey if you wanted a lot of them.
One of the most magical parts of the hologram for me is that if you cut it (the film media) in half, you have two copies of the hologram. The reduction in size is a loss of resolution - but the scene stays the same.
Though that also is part of the reason that a they're not more common. Each hologram is the film rather than a "print".
If someone wants to make 100 holograms to be able to sell them as more than a one off art piece you're making 100 units of the film.
> if you cut it (the film media) in half, you have two copies of the hologram.
A hologram is much like a window, you can look through a big window or a small window, and see what's at the other side both times, but the big window still gives you a lot more viewing angles than the small one. Cutting a hologram in half gives you half a hologram, not two copies of the hologram, it's just that you can change your viewing angle to still see what's on the other side, but that will be a different image than with the full hologram.
I remember as a kid having one of the Usborne books (80s) very badly illustrating this, and it gave completely the wrong idea about what you got; one chopped up hologram from a magazine later and I was sadder and wiser.
You get pretty much what you would naively expect from chopping up a hologram before reading that kind of misleading "two copies" text: exactly the same view of the object as you had from that part of the hologram before you cut it up.
It shows a hologram that has been cut into 3 pieces and the aspect of the viewpoint changing as you look through it, though each one has the full subject that was imaged.
My point is that while you can see the full subject you get it from the exact same point of view as that part of the hologram before it was chopped up.
If you couldn't see part of the subject from part of the intact plate you won't be able to after either.
The phrasing you used, "two copies of the hologram" is very misleading in the same way that my Usborne book was.
Chopping a hologram in half gives you two copies of the hologram in exactly the same sense that chopping a photo in half gives you two copies of the photo.
In both cases what you can see from that part of the plate/print is the same before and after you chop it up.
> Though that also is part of the reason that a they're not more common. Each hologram is the film rather than a "print".
This might be true for current processes but it seems like it should be possible to duplicate a hologram - use a hologram as a stand-in for the original scene when creating a new hologram. The result might have some blur (that progressively gets worse the more 'generations' you are from the original) but that seems like a solvable problem if someone worked at it.
I think the real reason we don't see them is more practical - it's amazing tech but a bit too much of a novelty in its current state, it's just not something that most people would want to put on their wall.
You could also cut them into pieces to duplicate the holograms. They would obviously be smaller. A cut hologram includes the whole hologram, just from the perspective of that part of the cut piece.
Glass plates likely wouldn't be the best choice for this.
Film sheets might be doable.
https://www.geola.com/product/pfg-01-film/ for a Lithuanian distributor. 35cm (about 1 foot) isn't that large. Might be able to cut it into 4ths (classic 4"x5") ... 2"x3" is a small size (12 per sheet).
I had the opportunity to work with a lenticular display a few years back. Just takes an HDMI input and can render a 3d scene like you'd build in Unity and you'd be able to see at least a range of aspects of the image at once by looking from different angles. Not fully 360 but maybe 90 degrees of perspective at once. It was neat but we spent weeks trying to make an impressive demo and none of it was fun for more than 5 seconds.
There are a few of us around who still make them. I do film photography and have my own darkroom already for that purpose. Adding holography on top of that is a relatively minor lift, and every once in a while the urge strikes and I'll get the equipment out.
The main challenge is that there are, to my knowledge, only two remaining manufacturers of the plates - in France, and in Russia.
There's a phenomenal book on this topic called "Holographic Visions" (ISBN 978-0198571223).
I've had the pleasure of working behind the scenes on holography related stuff (primarily optomechanics) for years now. Fascinating field full of phenomenally interesting minds.
I worked for Melbourne House in the mid 1980s and they made [Holografix actually made them] holograms of Nazgul to accompany their Lord of the Rings game. I've still got my sample buried in a box somewhere, it's not the full size one but about 1" square but still works pretty well.
These are a couple of links I've just looked up with information about it.
They always felt gimmicky to me, like something out of a kid's museum, and I imagine I'm not the only one.
Its this odd often blurry and hard to see thing that certainly has interesting aspects but is not something you can create easily at home, unlike a photograph. Then the world changed and mobile devices ruled and everyone had a good camera sensor in their pocket, TVs were thinner and higher resolution than ever, games started looking amazing, etc and there really wasn't any room for less practical things like holograms.
I think its one of those things we just weirdly romanticize like a car that is also a boat or a jetpack, but in reality has no real place as a consumer product.
There were different degrees of quality with holograms. To my recollection, a hologram on glass, that you illuminated with a laser, were stunning in clarity and sense of three dimensionality.
All other variants were degrees of magnitude worse.
The Science Museum in London used to have a life-sized holoportrait of Denis Gabor. It looked like a milky plate until you pushed the button that turned on the laser, and... there he was. Stunning.
There was a short-lived flurry of art establishment interest in high quality glass holograms, but the process is just too expensive and fragile to create non-niche art.
I always expected that at some point we'd have dynamic holographic displays, but the processing and resolution requirements are insane.
Holographic film has a resolution in the region of 100,000 to 250,000 ppi, which is quite a bit more than 300dpi for print or a few thousand PPI for plain old film. If you could build a 27" display with that resolution you'd need maybe 1TB per frame at a minimum.
You could probably apply quite a bit of compression to get that down on input, but that's still the order of a workable frame store memory.
You are describing transmission holograms, the best visual fidelity but it had to be illuminated by laser light. Reflection holograms had a small field of depth before getting blurry but we're visible in white light. Dichromate Gelating (DCG) holograms were also white-light visible, had a smaller depth field than reflection holograms, but we're very sharp and bright. A lot of novelties were made using the DCG process, like novelty glasses that had alien eyeballs in the lenses.
You don't need a laser but a monochromatic point source. Modern LEDs work quite well.
Depth of reflection holograms depends on the quality of the reference beam. A divergent one gives limited depth but a parallel or convergent one would give much more. But this is much more difficult to achieve.
It's possible to do this with digital methods, too, but the lower spatial resolution of most digital LCDs and most digital camera sensors (compared to film) limits it somewhat. But I think it'd be more practical than the analog film based analytical holograms.
The useful distinction in this thread is the one that explains the stall. A hologram stores the optical field, amplitude and phase, so depth and focus fall out of the reconstructed wavefront. A stereo pair never stored that field. It only fakes a couple of viewpoints. Recording the field wants coherent light and stability to a fraction of a wavelength. Showing it at video rate, across a wide angle, in ordinary room light, wants a modulator we still do not have cheaply. Film could do the slow version. Displays could not do the live one.
Holographic display tech is interesting stuff, but the tech in the article refers to laser holography on a holographic emulsion that is developed similar to a photographic chemical development process.
The touchable holograms, “fairy lights” seems to have not advanced at all, perhaps a dead end, but when I first read about it and thought of the possibilities it was all utterly amazing.
Monochromatic laser light makes these things look other-worldly. They look amazing and they look increadible, but its not even close to uncanny valley it's so unreal.
Widely used in commercial and military weapons sights.. EOTech (famous/infamous depending). The legendary FN (Belgian military contractor) just announced one.
I went to New York’s Museum of Holography in the 1980’s. It was on Mercer Street but it closed in the 90’s. I remember it was incredible, though, and I saw some techniques on display that I haven’t seen matched since.
There was one in London in Covent Garden market around the same era (perhaps a small chain, or perhaps just a similar name).
One image that I remember being particularly impressed by was a model of a radio telescope dish. You could look around the dish and see all the support gantry. The contrast between the smooth dish face and the structure on the other side made the 3D nature very dramatic.
On the counter they had a nice mirror illusion¹ of a floating "help" button - not a plate hologram but a really nice effect and you can still get these. They tend to be cheap plastic and dust and scratches affect them over time, but it's still a really nice effect if you've not seen it before.
At the Reuben H. Fleet in San Diego, their gift shop was a cornucopia of curiosities and knick-knacks for the Space Age. Including astronaut food, I got some amazing stuff there.
Once in the 1980s, their Science Center had some impressive hologram exhibits. There were vivid 3D images that you could walk around and inspect and marvel at. I was seriously amazed. So of course I felt compelled to purchase a hologram from the gift shop.
Well, the "hologram" I purchased was legit. It was a laser-produced headshot of a female model and it was 3D just like in the exhibit. Sadly, it was not really viable once I got it home.
You see, it was sold to me on a sheet of film, and that's it. It was totally inexpensive for them to produce, but it wasn't complete! The instructions or whatever, they said that it needed to be mounted and viewed in a cylinder with a strong light-source mounted inside! In other words, the enclosure and fixture equipment, not included, was essential to a good experience.
As a kid I really did feel cheated by that. Selling those films was sensational but utterly useless. I held onto that thing for years, though. You could kinda see it by holding it near a lightbulb and bending it. But it was a far cry from the exhibit that had commanded my childlike interest. Sadly.
I had a hologram from the old Edmund Scientific Catalog in the 70s, a flat piece of film and a green filter for a slide projector, which together would make a seaplane appear in the space in between. It worked, sorta, but it didn't help that I didn't have a slide projector and tried to make do with a flashlight instead.
There's a neat non-profit in Upstate NY, Holocenter, "center for the holographic arts". They have exhibits of currently working holographic artists, and you can do a workshop to make holograms: https://holocenter.org/
I thought at first this was about the cosmological theory of holography, that the whole universe is a projection of information located infinitely far away. Which is a hell of a cool mind-bender for sure, but it sounds like the most unfalsifiable thing one can imagine short of a diety.
I noped out of this site after 5 seconds of “verifying my connection.”
This trend is annoying and is punishing users to stop scraping of their stupid articles. I feel like 20 times a day I have to wait or click a box or something just so they can charge robots to read their public content.
I agree with you but honestly, better that than the endless visual chaos of all the ads and popups. If they can make revenue from bots and make the human reader experience better, then great. I'm not saying they won't do both.
I have no idea. I'm just curious if the fact that nobody uses "holografic sound" in the marketing means that we don't have equivalent tech for sound waves.
Very few people in the comments seem to understand what holography is. A hologram is not a “3D display” that mimics a sci-fi movie or TV show. A hologram is photographic media / display technology that records and transmits phase as well as intensity of incident photons. By capturing all the properties of the electromagnetic field that strikes the film, and re-emitting the same EM wave when stimulated, the hologram ends up being a full “3D picture” because after all, the light that hits your eyes ends up being the same as if you were looking at the actual scene. But that’s a consequence, not the defining property.
3blue1brown has a great explainer video on what holograms are: https://youtu.be/EmKQsSDlaa4
Well, yes, but actually, no...
"Hologram" is one of those words that has a wide variety of overlapping meanings. You can be a strict prescriptionist about it and insist that a real hologram involves laser light, interference patterns, 3D scene replication, phase preservation etc, but there will always be something that doesn't quite meet your definition that nevertheless is called a "hologram" by large numbers of people, even expert optical scientists:
A digital holographic stereogram prints an array of hogels (holographic pixels); the hogels themselves are holograms, but are mutually incoherent across the plate. When implemented to the highest level, the result is perceptually and behaviorally indistinguishable from an analog hologram.
A rainbow hologram (such as are found on credit cards) has single parallax only - it certainly does not capture all the properties of any particular electromagnetic field. No purity here, it's just a nifty tech for making things look 3D that happens to exploit wave interference. And everyone calls those holograms.
A scratch hologram is, to a first approximation, an extremely coarse version of a rainbow hologram, made by hand by engraving curved grooves in a reflective material. Now we're away from lasers and wave interference, and for this we sacrifice color - but geometrically we are still dealing with directional microreflections on a surface. Hologram? Depends who you ask.
Lenticular holograms use refraction rather than diffraction to achieve essentially the same imaging model as a rainbow hologram, but in a decidedly less finicky way, at the expense of some resolution. The same imaging data could be used to make a lenticular or a rainbow hologram. No lasers, no diffraction. Hologram? Depends who you ask...
My advice, as someone who has worked with holograms for a decade, is to give up. Saying "AKTUALLY Tupac/Abba isn't a hologram" gets old after the 1000th time. In the real world, "hologram" means "intangible optical simulacra", regardless of how it was achieved. If you want more precision than that, you have to specify the actual technology - Denisyuk, rainbow, lenticular, etc...
When someone asks "can you make a hologram of this", you don't lecture them on optical physics. You say "sure, you want the expensive kind or the plastic kind?"
Having also spent a long time in actual holography, I would agree with your assessment generally and your catalog of different "holographic" techniques.
I might quibble with lenticular displays, since they have a name that predates holography.
In the ideal world, a larger umbrella term would have emerged. "Autostereoscopic" describes any display that provides different views without glasses, but that typically suggests discrete views.
"Plenogram" would have been reasonable following Adelson and Bergen's plenoptic function, but that didn't and won't happen.
"Hologram" now basically means a sufficiently advanced three-dimensional display in popular culture. And that even leaves of other real holograms, such as the ones used for non-destructive testing.
Do these all actually only capture and display in stereo ?
What about the kind where you just slap an " H " for Hologram on someone's forehead and then tell everyone they're a real life hologram ?
Red Dwarf may have gotten this one right for comedic purposes :-D
https://en.wikipedia.org/wiki/Arnold_Rimmer
There’s such a big difference between the meaning that it took me a while to fighter this story out “ gravity is holographic” https://news.ycombinator.com/item?id=49845998
>You can be a strict prescriptionist about it
*prescriptivist
Fascinating, but I do wonder if you're not being the pedantic one here. All of these depend on reproducing the phase of a wavefront. Even a traditional hologram fails this purity test - you don't get a full intensity + phase map without taking multiple images with different phase of reference beam.
Mutually incoherent hogels ... the mind boggles.
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.
Yes, it's a tech that can be used to display in 3d, but not sure that's the best categorization choice overall.
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
[3] https://holowiki.org/wiki/Dichromated_Gelatin
I'm still a bit sad that light field cameras didn't take off.
Was there anything besides the Lytro?
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.
Their thing was more being able to change the focus after the fact
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.....
There are still light field cameras available, but they're all call for pricing industrial cameras.
2012, commercial availability (failed in 2018 and eaten by Google). 2017, used in scientific settings. 2021, sold commercially to consumers through kickstarter. 2026, multiple companies still sell light field cameras at modest quantities.
I wouldn’t say they “didn’t” take off. They’re gradually acquiring market share.
It's a light field rather than merely 3d, so you can record not only a 3D image of a microscope but also if you look down the hologram's eyepiece you get to see the thing it is focussed on: https://www.youtube.com/watch?v=K-ahG_Q2xRc
(I own a similar print, different microscope).
A properly constructed light field image can do this, so can a virtual reality headset or other "video game technology" system if it properly models refraction with ray tracing or another method.
"Another method" is doing a lot of heavy lifting there: computational holography is possible, has been for a while, but comparing it to raytracing is an apples-the-fruit to Apples-the-computer comparison.
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.
As a person trained in physics I’d say ray tracing is based on the ray theory of light whereas computational holography is based on the wave theory of light.
A headset only ever renders one viewpoint at a time. A hologram records and re-emits the whole light field all the time., so it is simultaneously viewable from every perspective.
Well, two viewpoints, one for each eye. And it adjusts what it renders when you move around so the effect is similar to a hologram and I'd say, competitive with it. If you are just one person the other views are wasted, and more than one person can share the same VR scene and get their own two viewpoints.
Holograms are cool but it is a finicky technology and speckle makes them visually ugly.
> I don't understand the distinction. You said it's not a 3d display, then described a 3d display technology.
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".
We can imagine a holographic display though. It would look like a window. Not a metaphor of a window, but an actual window. Like, a pane of glass you look through to see a real, physical scene on the other side, indistinguishable (to resolution limits) from the real thing.
One can hope we someday have this capability.
We have holographic displays, they have expensive components the picture sucks, and they're are on optical workbenches, but there is real hardware.
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.
I don't see the difference.
"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.
Not all holograms are displays, except in the sense that any piece of photographic film is a display.
The hologram described above certainly is.
A CRT doesn't display a picture, it produces a dot of photon emission which varies in color, intensity, and position over time across a 2D surface. The picture happens in your mind.
You can do things with holography that are impossible to do with any other 3D display. I. e. comparing two objects for sub-wavelength differences.
The irony is that actual holography is arguably more impressive than the sci-fi version once you understand what's happening
Speckle tends to make holograms look awful.
Holograms compete with many other display technologies such as stereograms, VR headsets, as well as volumetric and light field displays. This technology is described as "holographic"
https://lookingglassfactory.com/
but it looks better than holograms because it uses incoherent light field technology that doesn't have the speckle, plus the pipeline to make content for it doesn't require lasers, special equipment or special skills.
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Dan Smalley's research lab at BYU is actively developing 3D volumetric holography technology.
https://youtu.be/N12i_FaHvOU
The video is a bit old, but it has a few fun demos of the capabilities they've developed.
Strictly speaking that's not holography if I understood it correctly. Holography is based on interference created by a surface with a special pattern, and it doesn't require any matter other than the diffractive surface. Whereas here they say they move "particles" (what particles? dust? atoms?). Still pretty cool of course and a thing on its own.
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I'm not sure if you can edit, but consider removing the ?is= parameter, to keep the link anonymous.
Good catch, link updated!
Seems fun but also no idea how that could be scaled or made to work in consumer products.
It's "just" an engineering problem at that point though. It works. First it'll be at Disneyland for tens of millions of dollars and then it'll be in Vegas for millions of dollars and then eventually we'll be able to get it at BestBuy for $1,999 in 40 years.
That’s not a hologram though.
I wanted to pick up doing holography again, but I discovered that Integraf, founded by legend TJ ( https://www.integraf.com/about/tung-h-jeong ), stopped selling the film and supplies.
Much of the supply chain for modern hobbyist holography was sourced out of Russia, and the ongoing wars have made those materials unavailable.
There are some newer processes out there, but there were probably thousands of us that grew up using those HoloKit holography kits distributed by TJ.
You can get holographic film and kits from http://www.litiholo.com. These are not silver halide but are Covestro Bayfol HX photopolymer film which require no post processing.
And a battery powered laser
https://youtu.be/P5VEu77qe4Q
Wow, they have a laser with a shutter! The Litiholo kit just gives you a basic laser diode, and they don't tell you that you have to let the laser warm up before exposing the hologram. I made so many smeared/blurry holograms before I figured out you have to block the laser, turn it on and warm up, then unblock the laser.
Oh, I'd love to have a spare $6000 sitting around that I could buy^H^H^H reserve a holographic printer.
You can make dichromated gelatin film yourself which is cheap but quite tricky to do and requires a lot of work compared to the ready made film.
What is unique about the film and supplies?
The traditional emulsion had peak sensitivity at 633nm. I don't know much about it otherwise but it was much easier to handle as glass plates rather than film. Russia led the science of this for decades.
Silver halide based holographic plates are like conventional black and white photographic material, only extremely high resolution and very low sensitivity.
That's required because off-axis display holograms have spatial frequencies ranging from about 1200 line pairs per mm for transmission holograms to maybe 5000 for reflection holograms.
Because the grain size is so small, these plates tend to be pretty insensitive to light. That's why they have limited use outside of holography these days.
Other types of emulsions such as dichromated gelatin also exist but are also hard to find. DCG is even less sensitive to light.
In either case, the wavelength the material is sensitive to matters when exposing with a single frequency laser.
Then there are issues about the substrate if the emulsion is on film related to polarization preservation.
I went to a whole art exhibition of holograms as a kid that blew me away, and I've always wondered why holograms are so rare ever since. I had one for a while, the famous one of the microsope with the lens that you can actually look through to see a computer chip inside. There's nothing else like it.
Maybe if you could figure out a digital work flow with digital development method it could really take off. But holograms are analog and hard to deal with.
The price of entry to kick off digital photography was a fraction of a megapixel, the industry really kicked into high gear around VGA resolution which is about 1/3 of a megapixel and it was VERY plausible for the computers of the time to manipulate it, store it, transmit it, display it, edit it, etc.
A very "entry level" not good but maybe enough to kick off an industry digital transmission hologram would be like "hundreds of gigapixels" or at least dozens and thats not realistic for computers of this time. The super cool reflection holograms are much worse, like "many dozens of terapixels" to even begin to play with.
I guess its good news there are still frontiers of computation out there to reach. A lot of people believed progress would cease when computers could do high enough resolution video, and they're mostly correct, progress has halted for the general public. But if we ever get smart phones with low petabyte fast on device storage and display, those could realistically have "star trek" like transmission holograms.
That beings up some interesting issues WRT RF engineering. Shannons law and all that. Even with unimaginably complex compression algos will something like a hand held hologram video conference (similar to sci fi tropes) ever be possible? Maybe 60 PB/s would not be unreasonable. Consider the LHC only generates about 1 PB/s when its running and that takes a rather large distributed system and a lot of electricity. I don't think video conference holograms will be realistic... Strange thought experiment the only way to do a "holographic video conference" with sane data transfer rates and power levels might be to send the other side a LLM prompt and ask for a locally AI generated video hologram. "Here's 1000 jpeg pictures of me as raw data, render a hologram of me saying 'scotty beam me up'"
The display hardware tech would be pretty wild. I think it could be done but it would require a minimum of 1980s nanotechnology hype. Like DLP but using individual atoms not "large" silicon mirrors.
In summary the MVP for digital photography required early 1990s hardware, but the MVP for digital holograms requires a LOT more than 2020s hardware. Maybe in the 2040s, 2100s, who knows.
Me too, in Munich, must have been late 80s. Friend of mine also had "the book" and we dreamt of building our own lab in my basement. Sandbox on tire tube cushions and all.
I suspect, for your typical art nerd, holography is prohibitively expensive and limiting in expressiveness. And for your typical tech nerd, it's also prohibitively expensive and limiting in expressiveness.
Probably true, but I reckon there's surely at least some money to be made for a commercial enterprise if anyone wanted to go big, and nobody has. Get the price down via mass production and automation. Get some holograms into the shops. Sell them in an online store (you can buy holograms online already, but only a few from small operators at high prices, or second-hand). Let people send you their 3D models or 3D scenes and you'll send them a hologram of it. You can even do short animations (there's nothing stopping every new perspective being a different frame!). Have your AI convert people's photos to 3D and then output a hologram of them.
You do need to have a decent point light to shine on it, but you can sell that too. You can even sell a frame that has a clip-on light that's just right[1], although a perfect lighting setup is not required.
[1] Like Dutch Holographic Laboratory does: https://holoprint.com/pages/components.php#Telescope
>Let people send you their 3D models or 3D scenes and you'll send them a hologram of it.
Oh hey, I have worked in exactly this business (taking people's random 3D models and bullying a rendering pipeline into feeding a digital holographic printer). It's hard, for many reasons. Mainly it's that holograms are expensive in materials, labor, and capital outlay (adding up to several k just for something the size of a piece of paper), and mass production of digital holograms isn't really possible without massive further outlay - writing them is time consuming, and copying them is fraught. It's like being a graphic design / print workshop, except everything is way more fiddly and expensive and nobody wants your product.
Analog holograms are a bit more tractable. But that's even more niche on the consumption end.
It wasn't that prohibitive. When I did it, I had a helium neon laser recovered from an old supermarket scanner, but it can be done with one of those $10 keychain lasers. The chemicals weren't too expensive, but the holographic plates could get pricey if you wanted a lot of them.
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I'd love to see that microscope hologram in person
3blue1brown’s video on holography is one of the coolest math videos I’ve ever seen. Basically magic.
https://www.3blue1brown.com/lessons/holograms/
One of the most magical parts of the hologram for me is that if you cut it (the film media) in half, you have two copies of the hologram. The reduction in size is a loss of resolution - but the scene stays the same.
Though that also is part of the reason that a they're not more common. Each hologram is the film rather than a "print".
If someone wants to make 100 holograms to be able to sell them as more than a one off art piece you're making 100 units of the film.
> if you cut it (the film media) in half, you have two copies of the hologram.
A hologram is much like a window, you can look through a big window or a small window, and see what's at the other side both times, but the big window still gives you a lot more viewing angles than the small one. Cutting a hologram in half gives you half a hologram, not two copies of the hologram, it's just that you can change your viewing angle to still see what's on the other side, but that will be a different image than with the full hologram.
I remember as a kid having one of the Usborne books (80s) very badly illustrating this, and it gave completely the wrong idea about what you got; one chopped up hologram from a magazine later and I was sadder and wiser.
You get pretty much what you would naively expect from chopping up a hologram before reading that kind of misleading "two copies" text: exactly the same view of the object as you had from that part of the hologram before you cut it up.
A LitiHolo video from 7 years ago What happens when you cut a hologram in half? - https://youtu.be/9qpFAqZb-D4
It shows a hologram that has been cut into 3 pieces and the aspect of the viewpoint changing as you look through it, though each one has the full subject that was imaged.
Yes, I said I tried this when I was a kid.
My point is that while you can see the full subject you get it from the exact same point of view as that part of the hologram before it was chopped up.
If you couldn't see part of the subject from part of the intact plate you won't be able to after either.
The phrasing you used, "two copies of the hologram" is very misleading in the same way that my Usborne book was.
Chopping a hologram in half gives you two copies of the hologram in exactly the same sense that chopping a photo in half gives you two copies of the photo.
In both cases what you can see from that part of the plate/print is the same before and after you chop it up.
> Though that also is part of the reason that a they're not more common. Each hologram is the film rather than a "print".
This might be true for current processes but it seems like it should be possible to duplicate a hologram - use a hologram as a stand-in for the original scene when creating a new hologram. The result might have some blur (that progressively gets worse the more 'generations' you are from the original) but that seems like a solvable problem if someone worked at it.
I think the real reason we don't see them is more practical - it's amazing tech but a bit too much of a novelty in its current state, it's just not something that most people would want to put on their wall.
You could also cut them into pieces to duplicate the holograms. They would obviously be smaller. A cut hologram includes the whole hologram, just from the perspective of that part of the cut piece.
Glass plates likely wouldn't be the best choice for this.
Film sheets might be doable.
https://www.geola.com/product/pfg-01-film/ for a Lithuanian distributor. 35cm (about 1 foot) isn't that large. Might be able to cut it into 4ths (classic 4"x5") ... 2"x3" is a small size (12 per sheet).
That's Fourier space f**kery for you.
More substantially: cropping areas of the amplitude plot in freq space reduces detail but preserves overall image identity.
Agree, that is the first hologram that truly blows my mind. Literally windows to different dimension.
I had the opportunity to work with a lenticular display a few years back. Just takes an HDMI input and can render a 3d scene like you'd build in Unity and you'd be able to see at least a range of aspects of the image at once by looking from different angles. Not fully 360 but maybe 90 degrees of perspective at once. It was neat but we spent weeks trying to make an impressive demo and none of it was fun for more than 5 seconds.
There are a few of us around who still make them. I do film photography and have my own darkroom already for that purpose. Adding holography on top of that is a relatively minor lift, and every once in a while the urge strikes and I'll get the equipment out.
The main challenge is that there are, to my knowledge, only two remaining manufacturers of the plates - in France, and in Russia.
There's a phenomenal book on this topic called "Holographic Visions" (ISBN 978-0198571223).
I've had the pleasure of working behind the scenes on holography related stuff (primarily optomechanics) for years now. Fascinating field full of phenomenally interesting minds.
Have you commercialized anything?
I worked for Melbourne House in the mid 1980s and they made [Holografix actually made them] holograms of Nazgul to accompany their Lord of the Rings game. I've still got my sample buried in a box somewhere, it's not the full size one but about 1" square but still works pretty well.
These are a couple of links I've just looked up with information about it.
https://tolkienvisualcollectingguide.blogspot.com/2022/09/to...
https://www.mocagh.org/loadpage.php?getgame=lotrgameone
There’s a popular hologram by Walter Spierings that I think highlights what makes holograms unique: https://youtu.be/K-ahG_Q2xRc
It’s a microscope, that in the correct angle allows you to actually look down the viewfinder and see what the microscope was displaying.
This works because the hologram is recording the interference pattern of the photons that existed in the actual scene.
I’m really fascinated by these types of holograms and think they hold quite a bit of artistic potential.
Microscope blew my mind
They always felt gimmicky to me, like something out of a kid's museum, and I imagine I'm not the only one.
Its this odd often blurry and hard to see thing that certainly has interesting aspects but is not something you can create easily at home, unlike a photograph. Then the world changed and mobile devices ruled and everyone had a good camera sensor in their pocket, TVs were thinner and higher resolution than ever, games started looking amazing, etc and there really wasn't any room for less practical things like holograms.
I think its one of those things we just weirdly romanticize like a car that is also a boat or a jetpack, but in reality has no real place as a consumer product.
There were different degrees of quality with holograms. To my recollection, a hologram on glass, that you illuminated with a laser, were stunning in clarity and sense of three dimensionality.
All other variants were degrees of magnitude worse.
The Science Museum in London used to have a life-sized holoportrait of Denis Gabor. It looked like a milky plate until you pushed the button that turned on the laser, and... there he was. Stunning.
There was a short-lived flurry of art establishment interest in high quality glass holograms, but the process is just too expensive and fragile to create non-niche art.
I always expected that at some point we'd have dynamic holographic displays, but the processing and resolution requirements are insane.
Holographic film has a resolution in the region of 100,000 to 250,000 ppi, which is quite a bit more than 300dpi for print or a few thousand PPI for plain old film. If you could build a 27" display with that resolution you'd need maybe 1TB per frame at a minimum.
You could probably apply quite a bit of compression to get that down on input, but that's still the order of a workable frame store memory.
Multiply by three for colour.
You are describing transmission holograms, the best visual fidelity but it had to be illuminated by laser light. Reflection holograms had a small field of depth before getting blurry but we're visible in white light. Dichromate Gelating (DCG) holograms were also white-light visible, had a smaller depth field than reflection holograms, but we're very sharp and bright. A lot of novelties were made using the DCG process, like novelty glasses that had alien eyeballs in the lenses.
You don't need a laser but a monochromatic point source. Modern LEDs work quite well.
Depth of reflection holograms depends on the quality of the reference beam. A divergent one gives limited depth but a parallel or convergent one would give much more. But this is much more difficult to achieve.
They're also useful for analytical purposes.
It's possible to do this with digital methods, too, but the lower spatial resolution of most digital LCDs and most digital camera sensors (compared to film) limits it somewhat. But I think it'd be more practical than the analog film based analytical holograms.
The useful distinction in this thread is the one that explains the stall. A hologram stores the optical field, amplitude and phase, so depth and focus fall out of the reconstructed wavefront. A stereo pair never stored that field. It only fakes a couple of viewpoints. Recording the field wants coherent light and stability to a fraction of a wavelength. Showing it at video rate, across a wide angle, in ordinary room light, wants a modulator we still do not have cheaply. Film could do the slow version. Displays could not do the live one.
Oof, there's a pretty impressive startup in the space: https://lookingglassfactory.com/
Holographic display tech is interesting stuff, but the tech in the article refers to laser holography on a holographic emulsion that is developed similar to a photographic chemical development process.
Looks nice but the problem is always content.
The touchable holograms, “fairy lights” seems to have not advanced at all, perhaps a dead end, but when I first read about it and thought of the possibilities it was all utterly amazing.
The issue with these is that it’s very difficult to remove the sound that occurs when hot plasma expands.
So in addition to the skin damage that’s super obvious in this vid, you have this sharp buzzing crackling sound like some turbo sting gun.
https://youtu.be/SCmO0TZ1UEM?is=AbJMRunQxtPTO_DI
Monochromatic laser light makes these things look other-worldly. They look amazing and they look increadible, but its not even close to uncanny valley it's so unreal.
Widely used in commercial and military weapons sights.. EOTech (famous/infamous depending). The legendary FN (Belgian military contractor) just announced one.
I remember seeing an article in OMNI Magazine decades ago about "holographic data storage" which would have been incredibly high-density.
Not sure what became of it.
NYC also used to have the "Museum of Holography" which I was fortunately able to visit but may not exist anymore.
3D stuff, in general, seems to not do well. Not sure why! (as I dust off my Vision Pro)
I went to New York’s Museum of Holography in the 1980’s. It was on Mercer Street but it closed in the 90’s. I remember it was incredible, though, and I saw some techniques on display that I haven’t seen matched since.
There was one in London in Covent Garden market around the same era (perhaps a small chain, or perhaps just a similar name).
One image that I remember being particularly impressed by was a model of a radio telescope dish. You could look around the dish and see all the support gantry. The contrast between the smooth dish face and the structure on the other side made the 3D nature very dramatic.
On the counter they had a nice mirror illusion¹ of a floating "help" button - not a plate hologram but a really nice effect and you can still get these. They tend to be cheap plastic and dust and scratches affect them over time, but it's still a really nice effect if you've not seen it before.
¹ https://sandradodd.com/airpig.html
The Camera Obscura in Edinburgh has a selection of holographic images or used to.
The Museum of Holography still exists! Worth a visit next time you are in NYC.
They also offer classes and a residency program that I have been keenly considering.
At the Reuben H. Fleet in San Diego, their gift shop was a cornucopia of curiosities and knick-knacks for the Space Age. Including astronaut food, I got some amazing stuff there.
Once in the 1980s, their Science Center had some impressive hologram exhibits. There were vivid 3D images that you could walk around and inspect and marvel at. I was seriously amazed. So of course I felt compelled to purchase a hologram from the gift shop.
Well, the "hologram" I purchased was legit. It was a laser-produced headshot of a female model and it was 3D just like in the exhibit. Sadly, it was not really viable once I got it home.
You see, it was sold to me on a sheet of film, and that's it. It was totally inexpensive for them to produce, but it wasn't complete! The instructions or whatever, they said that it needed to be mounted and viewed in a cylinder with a strong light-source mounted inside! In other words, the enclosure and fixture equipment, not included, was essential to a good experience.
As a kid I really did feel cheated by that. Selling those films was sensational but utterly useless. I held onto that thing for years, though. You could kinda see it by holding it near a lightbulb and bending it. But it was a far cry from the exhibit that had commanded my childlike interest. Sadly.
I had a hologram from the old Edmund Scientific Catalog in the 70s, a flat piece of film and a green filter for a slide projector, which together would make a seaplane appear in the space in between. It worked, sorta, but it didn't help that I didn't have a slide projector and tried to make do with a flashlight instead.
I got to make one during a visit to the MIT museum maybe 25 years ago, was neat.
There's a neat non-profit in Upstate NY, Holocenter, "center for the holographic arts". They have exhibits of currently working holographic artists, and you can do a workshop to make holograms: https://holocenter.org/
I thought at first this was about the cosmological theory of holography, that the whole universe is a projection of information located infinitely far away. Which is a hell of a cool mind-bender for sure, but it sounds like the most unfalsifiable thing one can imagine short of a diety.
Know any good resources to read more ?
I noped out of this site after 5 seconds of “verifying my connection.”
This trend is annoying and is punishing users to stop scraping of their stupid articles. I feel like 20 times a day I have to wait or click a box or something just so they can charge robots to read their public content.
I agree with you but honestly, better that than the endless visual chaos of all the ads and popups. If they can make revenue from bots and make the human reader experience better, then great. I'm not saying they won't do both.
I want them to find a smarter way that doesn’t make my experience suck.
There’s enough sites who don’t have this annoying feature.
There used to be a hologram art gallery in San Francisco where you could get a hologram of yourself created.
https://computerchronicles.tv/#episode/1610 (Video, skip to 11:47)
Do we have an equvalent of a hologram for sound waves?
I would say Atmos (read: spatial audio) probably comes closest.
Does multi-mic recording and surround sound cover what you imagine?
I have no idea. I'm just curious if the fact that nobody uses "holografic sound" in the marketing means that we don't have equivalent tech for sound waves.
and stem cells! what happened to stem cells?
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