Posts belonging to Category optics



Virtual Images that Blend In And Interact With The Real-World

Avegant, a Silicon Valley startup that sells a pair of headphones equipped with a VR-like portable screen, is breaking into augmented reality. The company today announced that it’s developed a new type of headset technology powered by a so-called light field display.

Avegant ARCLICK ON THE IMAGE TO ENJOY THE VIDEO

The research prototype, which Avegant eventually plans on turning into a consumer product, is based on the company’s previous work with its Glyph projector. That device was a visor of sorts that floats a virtual movie screen in front of your eyes, and developing it gave Avegant insight into how to build an AR headset of its own.

Like Microsoft’s HoloLens and the supposed prototype from secretive AR startup Magic Leap, Avegant’s new headset creates virtual images that blend in and interact with the real-world environment. In a demo, the company’s wired prototype proved to be superior in key ways to the developer version of the HoloLens. Avegant attributes this not to the power of its tethered PC, but to the device’s light field display — a technology Magic Leap also claims to have developed, yet has never been shown off to the public.

The demo I experienced featured a tour of a virtual Solar System, an immersion within an ocean environment, and a conversation with a virtual life-sized human being standing in the same room. To be fair, Avegant was using a tethered and bulky headset that wasn’t all that comfortable, while the HoloLens developer version is a refined wireless device. Yet with that said, Avegant’s prototype managed to expand the field of view, so you’re looking through a window more the size of a Moleskine notebook instead of a pack of playing cards. The images it produced also felt sharper, richer, and more realistic.

In the Solar System demo, I was able to observe a satellite orbiting an Earth no larger than a bocce ball and identify the Big Red Spot on Jupiter. Avegant constructed its demo to show off how these objects could exist at different focal lengths in a fixed environment — in this case a converted conference room at the company’s Belmont, California office. So I was able to stand behind the Sun and squint until the star went out of focus in one corner of my vision and a virtual Saturn and its rings became crystal clear in the distance.

Source: http://www.theverge.com/

Nano-Implant Could Restore Sight

A team of engineers at the University of California San Diego (UC San Diego)  and La Jolla-based startup Nanovision Biosciences Inc. have developed the nanotechnology and wireless electronics for a new type of retinal prosthesis that brings research a step closer to restoring the ability of neurons in the retina to respond to light. The researchers demonstrated this response to light in a rat retina interfacing with a prototype of the device in vitro. The technology could help tens of millions of people worldwide suffering from neurodegenerative diseases that affect eyesight, including macular degeneration, retinitis pigmentosa and loss of vision due to diabetes.

Despite tremendous advances in the development of retinal prostheses over the past two decades, the performance of devices currently on the market to help the blind regain functional vision is still severely limited—well under the acuity threshold of 20/200 that defines legal blindness.

cortical neuronsPrimary cortical neurons cultured on the surface of an array of optoelectronic nanowires. Note the extensive neurite outgrowth and network formation

We want to create a new class of devices with drastically improved capabilities to help people with impaired vision,” said Gabriel A. Silva, one of the senior authors of the work and professor in bioengineering and ophthalmology at UC San Diego. Silva also is one of the original founders of Nanovision.

Power is delivered wirelessly, from outside the body to the implant, through an inductive powering telemetry system developed by a team led by Cauwenberghs.

The device is highly energy efficient because it minimizes energy losses in wireless power and data transmission and in the stimulation process, recycling electrostatic energy circulating within the inductive resonant tank, and between capacitance on the electrodes and the resonant tank. Up to 90 percent of the energy transmitted is actually delivered and used for stimulation, which means less RF wireless power emitting radiation in the transmission, and less heating of the surrounding tissue from dissipated power. For proof-of-concept, the researchers inserted the wirelessly powered nanowire array beneath a transgenic rat retina with rhodopsin P23H knock-in retinal degeneration.

The findings are published in a recent issue of the Journal of Neural Engineering.

Source: http://ucsdnews.ucsd.edu/

 

Nano-LED 1000 Times More Efficient

The electronic data connections within and between microchips are increasingly becoming a bottleneck in the exponential growth of data traffic worldwide. Optical connections are the obvious successors but optical data transmission requires an adequate nanoscale light source, and this has been lacking. Scientists at Eindhoven University of Technology (TU/e) now have created a light source that has the right characteristics: a nano-LED that is 1000 times more efficient than its predecessors, and is capable of handling gigabits per second data speeds.

NANO LEDWith electrical cables reaching their limits, optical connections like fiberglass are increasingly becoming the standard for data traffic. Over longer distances almost all data transmission is optical. Within computer systems and microchips, too, the growth of data traffic is exponential, but that traffic is still electronic, and this is increasingly becoming a bottleneck. Since these connections (‘interconnects’) account for the majority of the energy consumed by chips, many scientists around the world are working on enabling optical (photonic) interconnects. Crucial to this is the light source that converts the data into light signals which must be small enough to fit into the microscopic structures of microchips. At the same time, the output capacity and efficiency have to be good. Especially the efficiency is a challenge, as small light sources, powered by nano– or microwatts, have always performed very inefficiently to date.
The researchers in Eindhoven believe that their nano-LED is a viable solution that will take the brake off the growth of data traffic on chips. However, they are cautious about the prospects. The development is not yet at the stage where it can be exploited by the industry and the production technology that is needed still has to get off the ground.
The findings are reported in the online journal Nature Communications.

Source: https://www.tue.nl/

How To Fabricate The Hardest Diamond

The Australian National University (ANU) has led an international project to make a diamond that’s predicted to be harder than a jeweller’s diamond and useful for cutting through ultra-solid materials on mining sites. ANU Associate Professor Jodie Bradby said her team – including ANU PhD student Thomas Shiell and experts from RMIT, the University of Sydney and the United States – made nano-sized Lonsdaleite, which is a hexagonal diamond only found in nature at the site of meteorite impacts such as Canyon Diablo in the US.

diamond

This new diamond is not going to be on any engagement rings. You’ll more likely find it on a mining site – but I still think that diamonds are a scientist’s best friend. Any time you need a super-hard material to cut something, this new diamond has the potential to do it more easily and more quickly,” said Dr Bradby from the ANU Research School of Physics and Engineering.

Her research team made the Lonsdaleite in a diamond anvil at 400 degrees Celsius, halving the temperature at which it can be formed in a laboratory. “The hexagonal structure of this diamond’s atoms makes it much harder than regular diamonds, which have a cubic structure. We’ve been able to make it at the nanoscale and this is exciting because often with these materials ‘smaller is stronger‘.”

Lonsdaleite is named after the famous British pioneering female crystallographer Dame Kathleen Lonsdale, who was the first woman elected as a Fellow to the Royal Society.

The research is published in Scientific Reports.

Source: http://www.anu.edu.au/

Ultra Thin Nightvision Glasses Based On NanoPhotonics

Scientists from the Australian National University (ANU) have designed a nano crystal around 500 times smaller than a human hair that turns darkness into visible light and can be used to create light-weight night-vision glasses. Professor Dragomir Neshev from ANU said the new night-vision glasses could replace the cumbersome and bulky night-vision binoculars currently in use.

ultra-thin-nano-crystal-film_anu-1

The nano crystals are so small they could be fitted as an ultra-thin film to normal eye glasses to enable night vision,” said Professor Neshev from the Nonlinear Physics Centre within the ANU Research School of Physics and Engineering.

This tiny device could have other exciting uses including in anti-counterfeit devices in bank notes, imaging cells for medical applications and holograms.”

Co-researcher Dr Mohsen Rahmani said the ANU team’s achievement was a big milestone in the field of nanophotonics, which involves the study of behaviour of light and interaction of objects with light at the nano-scale.

nightvision-glasses

These semi-conductor nano-crystals can transfer the highest intensity of light and engineer complex light beams that could be used with a laser to project a holographic image in modern displays,” said Dr Rahmani, a recipient of the Australian Research Council (ARC) Discovery Early Career Researcher Award based at the ANU Research School of Physics and Engineering.

PhD student Maria del Rocio Camacho-Morales said the team built the device on glass so that light can pass through, which was critical for optical displays.

Source: http://www.anu.edu.au/

How To Generate Wonderful Colors

Colors are produced in a variety of ways. The best known colors are pigments. However, the very bright colors of the blue tarantula or peacock feathers do not result from pigments, but from nanostructures that cause the reflected light waves to overlap. This produces extraordinarily dynamic color effects.

blue-tarantulaScientists from Karlsruhe Institute of Technology (KIT) in Germany, in cooperation with international colleagues, have now succeeded in replicating nanostructures that generate the same color irrespective of the viewing angle.

In contrast to pigments, structural colors are non-toxic, more vibrant and durable. In industrial production, however, pigments have the drawback of being strongly iridescent, which means that the color perceived depends on the viewing angle. An example is the rear side of a CD. Hence, such colors cannot be used for all applications. Bright colors of animals, by contrast, are often independent of the angle of view. Feathers of the kingfisher always appear blue, no matter from which angle we look. The reason lies in the nanostructures: While regular structures are iridescent, amorphous or irregular structures always produce the same color. Yet, industry can only produce regular nanostructures in an economically efficient way. Radwanul Hasan Siddique, researcher at KIT in collaboration with scientists from USA and Belgium has now discovered that the blue tarantula does not exhibit iridescence in spite of periodic structures on its hairs. First, their study revealed that the hairs are multi-layered, flower-like structure. Then, the researchers analyzed its reflection behavior with the help of computer simulations. In parallel, they built models of these structures using nano-3D printers and optimized the models with the help of the simulations. In the end, they produced a flower-like structure that generates the same color over a viewing angle of 160 degrees. This is the largest viewing angle of any synthetic structural color reached so far.

Apart from the multi-layered structure and rotational symmetry, it is the hierarchical structure from micro to nano that ensures homogeneous reflection intensity and prevents color changes. Via the size of the “flower,” the resulting color can be adjusted, which makes this coloring method interesting for industry. “This could be a key first step towards a future where structural colorants replace the toxic pigments currently used in textile, packaging, and cosmetic industries,” says Radwanul Hasan Siddique of KIT’s Institute of Microstructure Technology, who now works at the California Institute of Technology. He considers short-term application in textile industry feasible. Dr. Hendrik Hölscher thinks that the scalability of nano-3D printing is the biggest challenge on the way towards industrial use. Only few companies in the world are able to produce such prints.

Source: http://www.kit.edu

NanoRobots With Grippers Travel Through the Bloodstream To Capture Cancer Cells

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used in a variety of applications, including microscopic actuators and grippers for surgical robots, light-powered micro-mirrors for optical telecommunications systems, and more efficient solar cells and photodetectors.

nanorobotsThis is a new area of science,” said Balaji Panchapakesan, associate professor of mechanical engineering at WPI and lead author of a paper about the new material published in Scientific Reports, an open access journal from the publishers of Nature. “Very few materials are able to convert photons directly into mechanical motion. In this paper, we present the first semiconductor nanocomposite material known to do so. It is a fascinating material that is also distinguished by its high strength and its enhanced optical absorption when placed under mechanical stress.”

Tiny grippers and actuators made with this material could be used on Mars rovers to capture fine dust particles.” Panchapakesan noted. “They could travel through the bloodstream on tiny robots to capture cancer cells or take minute tissue samples. The material could be used to make micro-actuators for rotating mirrors in optical telecommunications systems; they would operate strictly with light, and would require no other power source.”

Like other semiconductor materials, molybdenum disulfide, the material described in the Scientific Report paper, is characterized by the way electrons are arranged and move about within its atoms.

Source: https://www.wpi.edu/

Light Makes OscillatorTo Oscillate Indefinitely

Researchers have designed a device that uses light to manipulate its mechanical properties. The device, which was fabricated using a plasmomechanical metamaterial, operates through a unique mechanism that couples its optical and mechanical resonances, enabling it to oscillate indefinitely using energy absorbed from light.

metamaterialThis work demonstrates a metamaterial-based approach to develop an optically-driven mechanical oscillator. The device can potentially be used as a new frequency reference to accurately keep time in GPS, computers, wristwatches and other devices, researchers said. Other potential applications that could be derived from this metamaterial-based platform include high precision sensors and quantum transducers..

Researchers engineered the metamaterial-based device by integrating tiny light absorbing nanoantennas onto nanomechanical oscillators. The study was led by Ertugrul Cubukcu, a professor of nanoengineering and electrical engineering at the University of California San Diego. The work, which Cubukcu started as a faculty member at the University of Pennsylvania and is continuing at the Jacobs School of Engineering at UC San Diego, demonstrates how efficient light-matter interactions can be utilized for applications in novel nanoscale devices.

Metamaterials are artificial materials that are engineered to exhibit exotic properties not found in nature. For example, metamaterials can be designed to manipulate light, sound and heat waves in ways that can’t typically be done with conventional materials.

Metamaterials are generally considered “lossy” because their metal components absorb light very efficiently. “The lossy trait of metamaterials is considered a nuisance in photonics applications and telecommunications systems, where you have to transmit a lot of power. We’re presenting a unique metamaterials approach by taking advantage of this lossy feature,” Cubukcu said. The researchers also point out that because the plasmomechanical metamaterial can efficiently absorb light, it can function under a broad optical resonance. That means this metamaterial can potentially respond to a light source like an LED and won’t need a strong laser to provide the energy.

Using plasmonic metamaterials, we were able to design and fabricate a device that can utilize light to amplify or dampen microscopic mechanical motion more powerfully than other devices that demonstrate these effects. Even a non-laser light source could still work on this device,” said Hai Zhu, a former graduate student in Cubukcu’s lab and first author of the study.

Optical metamaterials enable the chip-level integration of functionalities such as light-focusing, spectral selectivity and polarization control that are usually performed by conventional optical components such as lenses, optical filters and polarizers. Our particular metamaterial-based approach can extend these effects across the electromagnetic spectrum,” adds Fei Yi, a postdoctoral researcher who worked in Cubukcu’s lab.

The research was published in the journal Nature Photonics.

Source: http://jacobsschool.ucsd.edu/

Nanocomputer: Carbon Nanotube Transistors Outperform Silicon

For decades, scientists have tried to harness the unique properties of carbon nanotubes to create high-performance electronics that are faster or consume less power — resulting in longer battery life, faster wireless communication and faster processing speeds for devices like smartphones and laptops. But a number of challenges have impeded the development of high-performance transistors made of carbon nanotubes, tiny cylinders made of carbon just one atom thick. Consequently, their performance has lagged far behind semiconductors such as silicon and gallium arsenide used in computer chips and personal electronics.

Now, for the first time, University of Wisconsin–Madison materials engineers have created carbon nanotube transistors that outperform state-of-the-art silicon transistors. Led by Michael Arnold and Padma Gopalan, UW–Madison professors of materials science and engineering, the team’s carbon nanotube transistors achieved current that’s 1.9 times higher than silicon transistors. The researchers reported their advance in a paper published in the journal Science Advances.

carbon nanotube integrated circuits

This achievement has been a dream of nanotechnology for the last 20 years,” says Arnold. “Making carbon nanotube transistors that are better than silicon transistors is a big milestone. This breakthrough in carbon nanotube transistor performance is a critical advance toward exploiting carbon nanotubes in logic, high-speed communications, and other semiconductor electronics technologies.”

This advance could pave the way for carbon nanotube transistors to replace silicon transistors and continue delivering the performance gains the computer industry relies on and that consumers demand. The new transistors are particularly promising for wireless communications technologies that require a lot of current flowing across a relatively small area.

Source: http://news.wisc.edu/

Smart Windows Control Light and Heat, Save Energy

View, previously Soladigm, is a Californian company working on the development of energy-saving smart windows based on electrochromism that can control light and heat while maintaining view and reducing glareView smart nanotechnology glass is now installed  in 250 commercial buildings.

VIEW smart glassCLICK ON THE IMAGE TO ENJOY THE VIDEO

Solar radiation and glare are reduced when the View glass is tinted, creating a comfortable indoor climate for occupants. By admitting natural daylight and rejecting unwanted solar glare, View Dynamic Glass significantly reduces annual energy costs. Control View Dynamic Glass from anywhere, create schedules, track energy efficiency and manage entire buildings with our mobile app.
View Dynamic Glass uses a proprietary electrochromic process to create smart glass in a world-class manufacturing facility. The best talent, equipment, and processes from the semiconductor, flat panel and solar industries produce dynamic glass in sizes up to 6 feet by 10 feet in many custom configurations. The factory combines leading-edge glass manufacturing with high technology processes and controls to deliver products that save energy, minimize heat and glare and allow occupants to enjoy the view to the outdoors. View Dynamic Glass is specified by architects for product performance, durability and energy savings.

Source: http://www.nextbigfuture.com/

Nanocomputer: How To Grow Atomically Thin Transistors

In an advance that helps pave the way for next-generation electronics and computing technologies—and possibly paper-thin gadgets —scientists with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) developed a way to chemically assemble transistors and circuits that are only a few atoms thick. What’s more, their method yields functional structures at a scale large enough to begin thinking about real-world applications and commercial scalability“This is a big step toward a scalable and repeatable way to build atomically thin electronics or pack more computing power in a smaller area,” says Xiang Zhang*, a senior scientist in Berkeley Lab’s Materials Sciences Division who led the study.

Their work is part of a new wave of research aimed at keeping pace with Moore’s Law, which holds that the number of transistors in an integrated circuit doubles approximately every two years. In order to keep this pace, scientists predict that integrated electronics will soon require transistors that measure less than ten nanometers in length (nanocomputer). Transistors are electronic switches, so they need to be able to turn on and off, which is a characteristic of semiconductors. However, at the nanometer scale, silicon transistors likely won’t be a good option. That’s because silicon is a bulk material, and as electronics made from silicon become smaller and smaller, their performance as switches dramatically decreases, which is a major roadblock for future electronics.

Researchers have looked to two-dimensional crystals that are only one molecule thick as alternative materials to keep up with Moore’s Law. These crystals aren’t subject to the constraints of silicon. In this vein, the Berkeley Lab scientists developed a way to seed a single-layered semiconductor, in this case the TMDC molybdenum disulfide (MoS2), into channels lithographically etched within a sheet of conducting graphene. The two atomic sheets meet to form nanometer-scale junctions that enable graphene to efficiently inject current into the MoS2. These junctions make atomically thin transistors.

assembly of 2D crystals
This schematic shows the chemical assembly of two-dimensional crystals. Graphene is first etched into channels and the TMDC molybdenum disulfide (MoS2) begins to nucleate around the edges and within the channel. On the edges, MoS2 slightly overlaps on top of the graphene. Finally, further growth results in MoS2 completely filling the channels.

This approach allows for the chemical assembly of electronic circuits, using two-dimensional materials, which show improved performance compared to using traditional metals to inject current into TMDCs,” says Mervin Zhao, a lead author and Ph.D. student in Zhang’s group at Berkeley Lab and UC Berkeley.

Optical and electron microscopy images, and spectroscopic mapping, confirmed various aspects related to the successful formation and functionality of the two-dimensional transistors. In addition, the scientists demonstrated the applicability of the structure by assembling it into the logic circuitry of an inverter. This further underscores the technology’s ability to lay the foundation for a chemically assembled atomic computer or nanocomputer, the scientists say. “Both of these two-dimensional crystals have been synthesized in the wafer scale in a way that is compatible with current semiconductor manufacturing. By integrating our technique with other growth systems, it’s possible that future computing can be done completely with atomically thin crystals,” says Zhao.

*Zhang also holds the Ernest S. Kuh Endowed Chair at the University of California (UC) Berkeley and is a member of the Kavli Energy NanoSciences Institute at Berkeley. Other scientists who contributed to the research include Mervin Zhao, Yu Ye, Yang Xia, Hanyu Zhu, Siqi Wang, and Yuan Wang from UC Berkeley as well as Yimo Han and David Muller from Cornell University.

Source: http://newscenter.lbl.gov/

How To Triple Perovskite Solar Cells Efficiency

A new type of two-dimensional-layered perovskite developed by Northwestern University, Los Alamos National Laboratory and Rice University researchers will open up new horizons for next-generation stable solar-cell devices and new opto-electronic devices such as light-emitting diodes, lasers and sensors.

The research team has tweaked its crystal production method and developed a 2-D perovskite with outstanding stability and more than triple the material’s previous power conversion efficiency. This could bring perovskite crystals closer to use in the burgeoning solar power industry.

flipping crystals

  • Crystal orientation has been a puzzle for more than two decades, and this is the first time we’ve been able to flip the crystal in the actual casting process,” said Hsinhan Tsai, a Rice graduate student at Los Alamos working with senior researcher and study lead co-author Aditya Mohite.

This is our breakthrough, using our spin-casting technique to create layered crystals whose electrons flow vertically down the material without being blocked, mid layer, by organic cations,” Tsai said.

Northwestern scientists created the two-dimensional material used by the researchers at Los Alamos in the new solar cells. Mercouri G. Kanatzidis, the Charles E. and Emma H. Morrison Professor of Chemistry in the Weinberg College of Arts and Sciences, and Costas Stoumpos, a postdoctoral fellow in Kanatzidis’ group, had been exploring an interesting 2-D material that orients its layers perpendicular to the substrate.

This breakthrough resulted from a very strong synergy between our institutions — the materials design team at Northwestern that designed and prepared high-quality samples of the materials and showed they are promising and the Los Alamos team’s excellent skills in making solar cells and optimizing them to high performance,” Kanatzidis said.

Wanyi Nie, a Los Alamos co-author on the paper, noted, “The new 2-D perovskite is both more efficient and more stable, both under constant lighting and in exposure to the air, than the existing 3-D organic-inorganic crystals.

The study was published July 6 by the journal Nature.

Source: http://www.lanl.gov/