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from the next:two-objects-in-the-same-space dept.
A team at Caltech has figured out a way to encode more than one holographic image in a single surface without any loss of resolution. The engineering feat overturns a long-held assumption that a single surface could only project a single image regardless of the angle of illumination.
The technology hinges on the ability of a carefully engineered surface to reflect light differently depending on the angle at which incoming light strikes that surface.
[...] Led by Andrei Faraon, assistant professor of applied physics and materials science in the Division of Engineering and Applied Science, the team developed silicon oxide and aluminum surfaces studded with tens of millions of tiny silicon posts, each just hundreds of nanometers tall. (For scale, a strand of human hair is 100,000 nanometers wide.) Each nanopost reflects light differently due to variations in its shape and size, and based on the angle of incoming light.
That last property allows each post to act as a pixel in more than one image: for example, acting as a black pixel if incoming light strikes the surface at 0 degrees and a white pixel if incoming light strikes the surface at 30 degrees.
"Each post can do double duty. This is how we're able to have more than one image encoded in the same surface with no loss of resolution," says Faraon (BS '04), senior author of a paper on the new material published by Physical Review X on December 7.
Seyedeh Mahsa Kamali et al, Angle-Multiplexed Metasurfaces: Encoding Independent Wavefronts in a Single Metasurface under Different Illumination Angles, Physical Review X (2017). DOI: 10.1103/PhysRevX.7.041056
Source: https://phys.org/news/2017-12-holograms-surface.html
(Score: 4, Interesting) by acid andy on Tuesday January 02 2018, @12:04AM (6 children)
First, they were able to fully encode a 3D image on a two dimensional surface (and that maybe a similar thing can encode a whole universe in lower dimensions according to the Holographic Principle [wikipedia.org]) but now they're saying they can fit two 3D images on there with no loss of detail. Intuitively this just seems nuts. Voodoo, I tell you. At the end of TFA they even mention the possibility of encoding three or more of the 3D images.
Still, I suppose it's not much stranger than how our visual field can have a 2 dimensional shape and yet seamlessly appear 3D and colored (so 4D) at the same time!
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 1, Insightful) by Anonymous Coward on Tuesday January 02 2018, @03:25AM (5 children)
The 4 known dimensions are height, width, depth, and time.
While color is a unique quality|property|characteristic (and takes more bits|more expensive film to store than monochrome), it isn't a dimension.
.
Now, those of you with imaginations working overtime, what is a new application for this new thing?
-- OriginalOwner_ [soylentnews.org]
(Score: 1, Funny) by Anonymous Coward on Tuesday January 02 2018, @08:12AM (2 children)
(Score: 2) by acid andy on Tuesday January 02 2018, @04:16PM (1 child)
Oh, definitely a higher dimension. It's geometry isn't perfectly smooth though, it's kind of quivery but in a good way. Quite a fast, good way.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by acid andy on Tuesday January 02 2018, @04:18PM
s/It's/Its but just the first one!
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 3, Informative) by rleigh on Tuesday January 02 2018, @12:13PM
There are three physical dimensions and one temporal dimension, it's true, but we do often consider progression within other spaces to be dimensions as well. This can include colour (wavelength progression in RGB/BGR/hyperspectral) and other "channels", coarse and fine subdivisions of time and space e.g. femtosecond lifetime within a coarser timeseries ranging from seconds to minutes or greater). And it can also include angle (rotation), tiling in x, y and z.
I work in scientific imaging, and all of these "dimensions" are stored (conceptually, if not practically), as an n-dimensional hypervolume comprising all the physical, temporal, colour/channel, and other additional dimensions used during image acquisition. The entire field uses "dimension" to include colour as well as the standard physical and temporal dimensions.
(Score: 2) by acid andy on Tuesday January 02 2018, @03:25PM
I'll grant that color is not a physical dimension of our universe. But a color needs multiple bits to store as you note and they are numerical variables that can be projected onto a color space, often represented using three dimensions e.g. RGB, HSV.
Our retinas and computer screens are two dimensional surfaces but they cannot represent any color at one single point. The retina has different cones sensitive to different colors at different positions on its surface and computer screens typically will have a repeating pattern of different color elements that mix together when viewed from a suitable distance. Similarly, when you mix different colored pigments, at the molecular level there would presumably only be one molecule of any given pigment at the uppermost level at each single point on the surface. Light may pass to lower levels before it is reflected or absorbed, but still, it doesn't seem possible to have any color existing at one single point on a truly two dimensional surface.
Of course even brightness can't be represented in an instantaneous moment on a single point because time needs to pass to count the number of photons striking each point.
Please correct me if I've got any of the physics wrong here.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?