Glasses-free 3-D projector (w/ Video)

Glasses-free 3-D projector (w/ Video): The MIT researchers—research scientist Gordon Wetzstein, graduate student Matthew Hirsch, and Ramesh Raskar, the NEC Career Development Associate Professor of Media Arts and Sciences and head of the Camera Culture group—built a prototype of their system using off-the-shelf components. The heart of the projector is a pair of liquid-crystal modulators—which are like tiny liquid-crystal displays (LCDs)—positioned between the light source and the lens. Patterns of light and dark on the first modulator effectively turn it into a bank of slightly angled light emitters—that is, light passing through it reaches the second modulator only at particular angles. The combinations of the patterns displayed by the two modulators thus ensure that the viewer will see slightly different images from different angles.

Life-size 3-D hologram-like telepods may revolutionize videoconferencing in the future

Life-size 3-D hologram-like telepods may revolutionize videoconferencing in the future: Two people simply stand infront of their own life-size cylindrical pods and talks to a 3D hologram-like images of each other. Cameras capture and track 3D video and convert into the life-size image.

Since the 3D video image is visible 360 degrees around the Pod, the person can walk around it to see the other person's side or back...


Dr. Vertegaal and his team used mostly existing hardware – including a 3D projector, a 1.8 metre-tall translucent acrylic cylinder and a convex mirror.

Holographic 3-D looks tantalizingly closer in 2012

Holographic 3-D looks tantalizingly closer in 2012: In their nanoscale system, they work with chips made by growing a layer of silicon oxide on to silicon wafer. They etch square patches of the silicon oxide. The result is a checkerboard-like pattern where etched-away pixels are nanometers lower than their neighbors. A reflective aluminum coating tops the chip. When laser light shines on the chip, it bounces off of the boundary between adjacent pixels at an angle. Diffracted light interferes constructively and destructively to create a 3-D picture where small mirrored platforms are moving up and down, many times a second, to create a moving projection. The process can also be described as the pixels closer to the light interfering with it one way and those further off, in another. The small distances between them generate the image that the eye sees.

Blog - Quantum Computing With Holograms

Blog - Quantum Computing With Holograms: In recent years, however, physicists have worked out how to make photons interact using interferometers and to carry out quantum computations using the output of one interferometer as the input for another...

The researchers then plan to stack the interferometers to perform simple quantum computations. "The approach here will "lock" these interferometers within a tempered piece of glass that is resistant to environmental factors," they say.
MacDonald and co suggest using a commercial holographic material called OptiGrate to store these holograms and show how these devices could carry out simple tasks such as quantum teleportation and CNOT logic.

Digital holographic microscopy allows for 50 times better resolution in viewing neurons | KurzweilAI

Digital holographic microscopy allows for 50 times better resolution in viewing neurons | KurzweilAI: The technique accurately visualizes the electrical activities of hundreds of neurons simultaneously, at up to 500 images per second — without damaging them with electrodes...

To understand how DHM works, imagine a large rock in an ocean of perfectly regular waves. As the waves deform around the rock and come out the other side, they carry information about the rock’s shape. This information can be extracted by comparing it to waves that did not smash up against the rock, and an image of the rock can be reconstructed.
DHM does this with a laser beam by pointing a single wavelength at an object (in this case, neurons), collecting the distorted wave on the other side, and comparing it to a reference beam.

One Per Cent: Quantum effect fuels colour-fast holograms

One Per Cent: Quantum effect fuels colour-fast holograms: "To overcome this, Kawata, Miyu Ozaki and Jun-ichi Kato harnessed a quantum surface effect. Metal films contain free electrons that oscillate on the surface and interact with incoming photons. Called a surface plasmon polariton, this surface wave is�confined within a light wavelength of the surface and can be harnessed to cause interference effects. By recording their holograms on 55-nanometre-thick metal films with red, green and blue lasers, they can ensure that the 3D image anybody sees is always the same colour - from any angle.

'Currently 3D TV receivers, 3D games machines and 3D movie theatre screens create an illusion using left and right eye images reconstructed by the brain,' says Kawata. 'We are creating an optical field in 3D from the actual object in natural colour - there is no illusion.'"

Holograms in True Color - ScienceNOW

Holograms in True Color - ScienceNOW: Now, researchers report today in Science that they can create true-color holograms that can be viewed using only white light. Like the first holograms, the new technique uses lasers to generate an interference pattern, says Satoshi Kawata, a photonics physicist at Osaka University in Japan. To capture colors, Kawata and his colleagues illuminate the original object with three different lasers: red, blue, and green, the three primary colors of projected light. They store the hologram in a light-sensitive material coated with a thin layer of metal such as gold or silver, a veneer that contains free electrons that are easily excited when struck by radiation such as light waves.

To reproduce a 3D image, the researchers bathe the metal-sheathed material in ordinary white light, which contains all wavelengths of visible light (including red, blue, and green). That white light excites the free electrons; their resulting movements and oscillations (so-called surface plasmons) in turn give off light that regenerates the image

DARPA SUCCESSFULLY COMPLETES 3D HOLOGRAPHIC DISPLAY TECHNOLOGY DEMONSTRATION PROGRAM

Defense Advanced Research Projects Agency: It permits simultaneous viewing for up to 20 participants and is interactive, allowing the image to be frozen, rotated and zoomed up to the resolution limit of the data. The holographic display enables full visual depth capability up to 12 inches. The technology also enables realistic two-dimensional printouts of the 3D imagery that front line troops can take with them on missions.

UPSD is based on full-parallax technology, which enables each 3D holographic object to project the correct amount of light that the original object possessed in each direction, for full 360- degree viewing.  Current 3D displays lack full-parallax and only provide 3D viewing from certain angles with typically only three to four inches of visual depth.

3D, 360-degree fog display shown off (w/ video)

3D, 360-degree fog display shown off (w/ video): Researchers at Osaka University in Japan have made a 3D and 360-degree display that projects from a variety of different angles onto a cylindrical fog display. This combination of multiple-point of view projectors and the cylinder allows for a display that is 3D no matter what side you view it from, though in order to get a holodeck style of projection a much larger set of projectors, and a lot more fog, would need to be on hand.

Tying the knot with computer-generated holograms: Winding optical path moves matter

Tying the knot with computer-generated holograms: Winding optical path moves matter: Knotted traps are made by imprinting a computer-generated hologram on the wavefronts of an otherwise ordinary beam of light. NYU undergraduate student Elisabeth Shanblatt and NYU physicist David Grier, the authors of the Optics Express paper, use a "liquid-crystal spatial light modulator" to project their holograms. This is essentially the first cousin of a conventional LCD television screen. The spatial light modulator imprints a calculated pattern of phase shifts onto the light. When the modified beam is brought to a focus with a high-power lens, the region of maximum intensity takes the form of a 3-D curve. This curve can cross over and through itself to trace out a knot. Moreover, the same hologram can redirect the light's radiation pressure to have a component along the curve, so that the total optical force "threads the knot."
When Shanblatt and Grier began this investigation, they thought that creating knots would be a compelling and aesthetically pleasing demonstration of their method's power. Once the knots actually worked, they realized that there are very few—if any—other practical ways to create knotted force fields. Previously reported knotted vortex fields have intensity minima along the knot, rather than the intensity maxima, or "bright knots" that can be created using the computer-generated holograms.

Ultrasound beam lets scientists see deep into human tissue | KurzweilAI

Ultrasound beam lets scientists see deep into human tissue | KurzweilAI: Wang’s guide star is an ultrasound beam that “tags” light that passes through it. When it emerges from the tissue, the tagged light, together with a reference beam, creates a hologram.

When a “reading beam” is then shown back through the hologram, it acts as a time-reversal mirror, creating light waves that follow their own paths backward through the tissue, coming to a focus at their virtual source, the spot where the ultrasound is focused.

3-D TV? How about holographic TV?

3-D TV? How about holographic TV?: Mark Lucente, director of display products for Zebra Imaging in Austin, Texas, which is commercializing holographic displays for videoconferencing applications, says that his company’s prospective customers are often uncomfortable with the sheer computational intensity of holographic video. “It’s very daunting,” he says. “1.5 gigabytes per second are being generated on the fly.” By demonstrating that off-the-shelf components can keep up with the computational load, Lucente says, Bove’s group is “helping show that it’s within the realm of possibility.” Indeed, he says, “by taking a video game and using it as an input device, [Bove] shows that it’s a hop, skip and a jump away from reality.”

Scientists make holograms of atoms using electrons

Scientists make holograms of atoms using electrons: In their experiments, the scientists beamed an intense infrared laser light at an atom or molecule, which resulted in the atom or molecule becoming ionized and releasing an electron. The laser field causes the liberated electron to oscillate away from and toward the ion. Sometimes, an electron and ion collide, releasing a very short burst of radiation.
Because the electron motion is fully coherent, meaning it always has the same phase, the scientists realized that they could apply holographic techniques to record information about the ion and electron. The key to holographic electron imaging is to observe the interference between a reference wave (which is emitted by the electron and doesn’t interact with the ion) and a signal wave (which scatters off the ion and encodes its structure). When the reference wave and signal wave interfere on a detector, the encoded information about the electron and ion is stored and can be viewed in the future. As the scientists explained, the result is a hologram of an atom produced by its own electrons.

A Step toward Holographic Videoconferencing - Technology Review

A Step toward Holographic Videoconferencing - Technology Review: "By improving the materials used to make the display and the optical system used to encode the images, they have now demonstrated a full-color holographic display that refreshes every two seconds. This work is described today in the journal Nature.

The key to the technology is a light-responsive polymer composite layered on a 12-inch-by-12-inch substrate and sandwiched between transparent electrodes. The composite is arranged in regions called "hogels" that are the holographic equivalent of pixels. Writing data to the hogels is complex, and many different compounds in the composite play a role. When a hogel is illuminated by an interference pattern produced by two green laser beams, a compound called a sensitizer absorbs light, and positive and negative charges in the sensitizer are separated. A polymer in the composite that's much more conductive to positive charges than negative ones pulls the positive charges away.

This charge separation generates an electrical field that in turn changes the orientation of red, green, and blue dye molecules in the composite. This change in orientation changes the way these molecules scatter light. It's this scattering that generates a 3-D effect. When the hogel is illuminated with light from an LED, it will scatter the light to make up one visual point in the hologram."