Technology will benefit display companies in manufacturing low cost and light weight 2D/3D convertible displays for mobile applications
Convertible video displays that offer both 2D and 3D imaging without the need of any eyewear offer greater convenience to users who would otherwise have to keep track of yet another accessory. Such autostereoscopic displays have already hit the TV market, but the underlying technology reveals its limitations at close viewing distances. Viewers typically must view these displays from a distance of around one meter (about three feet), eliminating any practical applicability to the smaller screens of mobile devices.
Researchers at Seoul National University, South Korea, however, have developed a new method of making these convertible displays that not only achieved near-viewing capabilities, but also simplified and shrank the architecture of the technology. In a paper published this week in the journal Optics Express, from The Optical Society (OSA), researchers describe their novel design.
For eyewear-free displays, the only action is behind the screen where the images’ pixels and optics are layered together to produce the stereoscopic effect. The two primary ways of producing these optically illusive effects are by using either an array of micro-lenses, called lenticular lenses, or an array of micro-filters, called parallax barriers, in front of the image to make its appearance depend on the angle at which it is being seen.
The simplest example of this effect is found on a movie poster whose image appears to change as you walk by. Two (or more) images are interlaced and printed behind a plastic layer with grooves matching the interlaced pattern. The grooves act as distinct, interlaced arrays of lenses or filters, revealing one image as you approach the poster and another as you depart, viewing the same poster from a different angle.
In the case of 2D/3D convertible screens, these layers are active, meaning they can be (electronically) switched on or off. The gap distance between the image layer and the barrier layer is a key determinant of the viewing distance. Closer stacking of these layers together allows for a closer viewing distance.
In their paper, Sin-Doo Lee, a professor of electrical engineering at Seoul National University, and his colleagues describe a monolithic structure that effectively combines the active parallax barrier, a polarizing sheet and an image layer into a single panel. Instead of two separate image and barrier panels, they use a polarizing interlayer with the image layer in direct contact with one side of the interlayer, while the active parallax barrier of a liquid crystal layer is formed on the other side as an array of periodically patterned indium-tin-oxide (ITO) electrodes.
The use of this interlayer allows the minimum separation of the image and barrier layers, thus providing the short viewing distance required for the smaller screens of mobile devices.
“The polarizing interlayer approach here will allow high resolution together with design flexibility of the displays, and will be applicable for fabricating other types of displays such as viewing-angle switchable devices,” Lee said. “Our technology will definitely benefit display companies in manufacturing low cost and light weight 2D/3D convertible displays for mobile applications. Under mobile environments, the weight is one of the important factors.”
This concept not only applies to LC-based 2D/3D displays, but also to OLED-based 2D/3D displays, offering application to a broad range of present and future device designs.
A South Korean research team has developed new technology to improve tabletop holographic displays
Princess Leia, your Star Wars hologram moment may be redeemed. In the original ‘Star Wars’ movie, the inviting but grainy special effects hologram might soon be a true full-color, full-size holographic image, due to advances by a South Korean research team refining 3-D holographic displays.
The team described a novel tabletop display system that allows multiple viewers to simultaneously view a hologram showing a full 3-D image as they walk around the tabletop, giving complete 360-degree access. The paper was published this week in the journal Optics Express, from The Optical Society (OSA).
To be commercially feasible in a range of applications — from medicine to gaming to media — the hologram challenge is daunting. It involves scaling an electronic device to a size small enough to fit on a table top, while making it robust enough to render immense amounts of data needed to create a full-surround 3-D viewing experience from every angle — without the need for special glasses or other viewing aids.
“In the past, researchers interested in holographic display systems proposed or focused on methods for overcoming limitations in the combined spatial resolution and speed of commercially available, spatial light modulators. Representative techniques included space-division multiplexing (SDM), time-division multiplexing (TDM) and combination of those two techniques,” explained Yongjun Lim, of the 5G Giga Communication Research Laboratory, Electronics and Telecommunications Research Institute, South Korea. Lim and his team took a different approach. They devised and added a novel viewing window design.
To implement such a viewing window design, close attention had to be paid to the optical image system. “With a tabletop display, a viewing window can be created by using a magnified virtual hologram, but the plane of the image is tilted with respect to the rotational axis and is projected using with two parabolic mirrors,” Lim explained. “But because the parabolic mirrors do not have an optically-flat surface, visual distortion can result. We needed to solve the visual distortion by designing an aspheric lens.”
Lim further noted, “As a result, multiple viewers are able to observe 3.2-inch size holograms from any position around the table without visual distortion.”
Building on these advances, Lim’s team hopes to implement a key design feature of strategically sizing the viewing window so it is closely related to the effective pixel size of the rotating image of the virtual hologram. Watching through this window, observers’ eyes are positioned to accept the holographic image light field because the system tilts the virtual hologram plane relative to the rotational axis. To enhance the viewing experience the team hopes to design a system in which observers can see 3.2-inch holographic 3-D images floating on the surface of the parabolic mirror system at a rate of 20 frames per second.
Test results of the system using a 3-D model and computer-generated holograms were promising — though right now still in a monochrome green color. Next, the team wants to produce a full-color experience and resolve issues related to undesirable aberration and brightness mismatch among the four digital micromirror devices used in the display.
“We are developing another version of our system to solve those issues and expect to have the next model in the near future, including enhancement of the color expression,” said Lim. “Many people expect that high quality holograms will entertain them in the near future because visualizations are increasingly sophisticated and highly imaginative due to the use of computer-aided graphics and recently-developed digital devices that provide augmented or virtual reality.”
And the Princess Leia hologram? That old miniature was a motivating experience of their work, Lim explained.
First use of quantum technology to create a random number generator that is both tiny and fast
Random number generators are crucial to the encryption that protects our privacy and security when engaging in digital transactions such as buying products online or withdrawing cash from an ATM. For the first time, engineers have developed a fast random number generator based on a quantum mechanical process that could deliver the world’s most secure encryption keys in a package tiny enough to use in a mobile device.
In The Optical Society’s journal for high impact research, Optica, the researchers report on their fully integrated device for random number generation. The new work represents a key advancement on the path to incorporating quantum-based random number generators — delivering the highest quality numbers and thus the highest level of security — into computers, tablets and mobile phones.
“We’ve managed to put quantum-based technology that has been used in high profile science experiments into a package that might allow it to be used commercially,” said the paper’s first author, Carlos Abellan, a doctoral student at ICFO-The Institute of Photonic Sciences, a member of the Barcelona Institute of Science and Technology, Spain. “This is likely just one example of quantum technologies that will soon be available for use in real commercial products. It is a big step forward as far as integration is concerned.”
The new device operates at speeds in the range of gigabits per second, fast enough for real-time encryption of communication data, such as a phone or video calls, or for encrypting large amounts of data traveling to and from a server like that used by a social media platform. It could also find use in stock market predictions and complex scientific simulations of random processes, such as biological interactions or nuclear reactions.
Shrinking the truly random
The random number generators used today are based on computer algorithms or the randomness of physical processes — essentially complex versions of rolling dice over and over again to get random numbers. Although the numbers generated appear to be random, knowing certain information, such as how many “dice” are being used, can allow hackers to sometimes figure out the numbers, leaving secured data vulnerable to hacking.
The new device, however, generates random numbers based on the quantum properties of light, a process that is inherently random and thus impossible to predict no matter how much information is known. Although other researchers have developed quantum random number generators, they have all been either larger or slower than the device reported in the Optica paper.
“We have previously shown that the quantum processes taking place exhibit true randomness,” said Valerio Pruneri, who led the collaborative research effort. “In this new paper, we made a huge technological advance by using a new design that includes two lasers that interfere with each other in a confined space. This makes the device smaller while keeping the same properties that were used in the past experiments.”
Creating a practical device
The researchers used photonic integrated circuit (PIC) technology to create two quantum number generators that together measure 6 by 2 millimeters. PIC technology offers a way to integrate photonic components — such as the lasers and detectors used by the new quantum random generator — onto a chip with a small footprint and low power consumption. Most importantly, PIC-based devices can be integrated with traditional electronics, which could allow the random number generator to be used with the driving, reading and processing electronics necessary for computation or communications.
“We proved that quantum technologies are within practical reach by exploiting PICs,” said Pruneri. “Quantum random number generation as well as quantum cryptography and other quantum-based technologies will benefit from PIC-based technology because it allows one to build commercial and innovative products. Ours is a first demonstration.”
Using a heat-resistant device, made of tungsten and alumina layers, researchers from Aalborg University have found that the device can absorb the sun’s broad spectrum radiation and convert it to electricity
The photovoltaic (PV) cells in traditional solar cells convert sunlight efficiently within a narrow range of wavelengths determined by the material used in the PV cells. This limits their efficiency, as long wavelengths of sunlight are not converted at all and the energy of short wavelength light is largely wasted. Scientists have sought to increase the efficiency of photovoltaics by creating “multi-junction” solar cells, made from several different semiconductor materials that absorb at varying wavelengths of light. The problem is, such multi-junction cells are expensive to make.
Broadband solar absorption previously has been achieved using metal-insulator-metal (or MIM) resonators, which consist of an insulator sandwiched between a thick bottom and a thin top layer, each made of metals like chromium and gold. The metal components used in MIM resonators have relatively low melting points—temperatures that are reduced further when the materials are in very thin layers, as in the resonators, because of a phenomenon called melting point depression, in which the melting point of a material scales down as the dimensions of the material decrease. The metals in standard MIM resonators melt at around 500 degrees Celsius, hindering their usefulness in solar cells.
Now a group of researchers in Denmark have discovered an alternative method to capture a broad spectrum of sunlight using a heat-resistant device made of tungsten and alumina layers that can be fabricated using inexpensive and widely available film-deposition techniques. The researchers describe their work and the new material in a paper published this week in the journal Optical Materials Express, from The Optical Society (OSA).
“They are resistant to heat, including thermal shock, and exhibit stable physical and chemical properties at high temperatures,” explained Manohar Chirumamilla of Aalborg University in Denmark, the first author of the new paper. This allows the absorbers to maintain their structural properties at very high temperatures.
In experiments, the new absorbers were shown to operate at a temperature of 800 degrees Celsius and to absorb light of wavelengths ranging from 300 to 1750 nanometers, that is, from ultraviolet (UV) to near-infrared wavelengths.
“MIM resonators absorbing in the spectral region from UV to near-infrared can be directly employed in different applications, such as solar TPV [thermophotovoltaic] /TPV systems and solar thermal systems,” Chirumamilla said. “Other potential applications include in so-called tower power plants, where concentrated solar light generates steam to drive a generator.”
“This is the first step in utilizing the energy of the sun in a more efficient way than with current solar cells,” he added. “Using an emitter in contact with our absorber, the generated heat can then be used to illuminate a solar cell—which can then function more efficiently when it is placed directly in the sun.”
The Optical Society (OSA) is a professional society in optics and photonics, home to accomplished science, engineering, and business leaders from all over the world.
Through publishing, conferences and exhibitions, membership, and education, the Society supports achievement in the science of light. The organization has members in more than 100 countries. As of 2013, OSA has 18,500 individual members, more than 230 corporate member companies, and supports and optics and photonics community of more than 180,000 people worldwide.
The mission of the Optical Society is to promote the generation, dissemination, application, and archiving of knowledge in optics and photonics. The purposes of the Society are scientific, technical, and educational.
The Latest Updated Research News:
The Optical Society (OSA) research articles from Innovation Toronto
- Lasers Help Speed Up the Detection of Bacterial Growth in Packaged Food and Other Environments – March 20, 2016
- Thin 3D Display for Comfortable Smart Phone Viewing – February 24, 2016
- Shooting Lightning Out of the Sky – September 25, 2015
- Engineers Unlock Remarkable 3D Vision from Ordinary Digital Camera Technology – September 18, 2015
- A New Design for an Easily Fabricated, Flexible and Wearable White-Light LED – August 22, 2015
- A New LCD Display Screen that Have to Use Any Power – October 24, 2014
- Atomically thin material opens door for integrated nanophotonic circuits – September 7, 2014
- New Hand-Held Device Uses Lasers, Sound Waves for Deeper Melanoma Imaging – August 8, 2014
- New technology for carving light into Gorilla® Glass could let manufacturers pack more apps into new real estate: The display glass itself – June 20, 2014
- New biometric watches use light to non-invasively monitor glucose, dehydration, pulse – June 12, 2014
- Low Power, Longer Distance, Tiny Package: New Laser Sensing Technology for Self-driving Cars, Smartphones and 3-D Video Games – May 30, 2014
- Let the Sun Shine In: Redirecting Sunlight to Urban Alleyways – April 16, 2014
- Early Detection of Blinding Eye Disease Could be as Easy as Scanning a Barcode | ophthalmic-screening instrument
- Zoomable Holograms Pave the Way for Versatile, Portable Projectors
- Inspired by the human eye, imaging system detects disease, hazardous substances
- Optical sensors improve railway safety
- Scientists Rig Hospital-grade Lightweight Blood Flow Imager on the Cheap
- First real-time detector for IV delivered drugs may help eliminate life-threatening medical errors
- A Telescope For Your Eye: New Contact Lens Design May Improve Sight of Patients with Macular Degeneration
- Behold the 9-Day Fresh Strawberry
- New Single Virus Detection Techniques for Faster Disease Diagnosis
- Charred Micro-Bunny Sculpture Shows Promise of New Material for 3-D Shaping
- Just how secure is quantum cryptography?
- New LED Streetlight Design Curbs Light Pollution
- New camera system creates high-resolution 3-D images from up to a kilometer away
- New Imaging Device That Is Flexible, Flat, and Transparent
- Eco-friendly Optics: Spider Silk’s Hidden Talents Brought to Light for Applications in Biosensors, Lasers, Microchips
- From Lectures to Explosives Detection: Green Laser Pointer Identifies Traces of Dangerous Chemicals in Real-Time
- Cyborg Surgeon: Hand and Technology Combine in New Surgical Tool That Enables Superhuman Precision
- NEXT GENERATION 3-D THEATER: OPTICAL SCIENCE MAKES GLASSES A THING OF THE PAST
- Laser Scalpels Get Ultrafast, Ultra-Accurate, and Ultra-Compact Makeover
- Scientists transform iPhones into medical imaging devices
- New Depiction of Light Could Boost Telecommunications Channels
- New High-Speed 3-D Imaging System Holds Potential for Improved Cancer Screening