Technology Trends

In this article, the Register writes that “camera phones will soon have lenses made from nothing more substantial that a couple of drops of oil and water, but will still be capable of auto focusing, and even zooming in on subjects.” The lenses, developed by the French company Varioptic, contain drops of oil and water, acting respectively as conductor and insulator, and sandwiched between two windows. These liquid lenses could replace glass or plastic ones because of several advantages: no moving parts, leading to better reliability; a very small power consumption; very small dimensions (diameter: 8mm; thickness: 2mm); and a very fast response time of 2/100th of a second. You can expect the first camera phones using these liquid lenses as early as Christmas 2005. These lenses might also appear in medical equipment, such as endoscopes, optical networking equipment or surveillance devices. Read more…

The company was founded two years ago to exploit two core technology patents covering lenses based on the principles of electrowetting. This is the tendency of liquid to spread on a substrate, explains Etienne Paillard, the CEO of the company. “It means we can tune the shape of the drop to create a lens. Think about a tunable lens, like in the human eye,” he suggests.

The lens has a simple structure: two liquids, of equal density, sandwiched between two windows in a conical vessel. One liquid is water, which is conductive. The other, oil, acts as a lid, allowing the engineers to work with a fixed volume of water, and provides a measure of stability for the optical axis. The interface between the oil and water will change shape depending on the voltage applied across the conical structure. At zero volts, the surface is flat, but at 40 volts, the surface of the oil is highly convex, Paillard said.

What are the advantages of these liquid lenses?

There are several obvious advantages to having a lens built like this. Because there are no moving parts, there is less to break and it should be more rugged. Power consumption is also very low: around a tenth of that of a motorised auto focus lens.

It also has the potential to be made very small. Paillard says that at the moment, the limit is a couple of millimetres, but that the company is researching ways of shrinking the lens further. Varioptics is now developing the lens for use in endoscopy as well as in camera phones. But the camera phone market is its priority right now.

And when will we see the first camera phones equipped with these lenses?

The company has a non-exclusive licensing deal with a subsidiary of Samsung to develop the lenses for use in its camera phones. Paillard expects products will be on the shelves by Q1 2006 at the latest, and maybe even in time for Christmas next year.

The first product will be the auto focussing lens, but in another year’s time Varioptics will have a true zoom capability, using two of the liquid lenses, Paillard says. “We’ve just proven in simulation that a 3x zoom is possible. We’re building the prototype now.”

Varioptic has filed two patents to protect its technologies. Here are the direct links to a lens with variable focus and a method for centering a drop of liquid on a given point on a surface.

If for a reason or another, these links appeared to be broken, please go to the Intellectual Property Digital Library which provides access to intellectual property data collections hosted by the World Intellectual Property Organization (WIPO). Then choose the patents database and enter the numbers of the patents in the search box. These numbers are respectively 99/18456 and 00/58763.

It’s worth noting that the Register published in March 2004 a story named “The $5 ‘no moving parts’ fluid zoom lens — twice” in which it compared the Varioptic patents with another one filed by Philips. As the Philips patent clearly made references to the Varioptic ones, it is highly possible that Philips needs to license the Varioptic technology if it wants to use it.

Sources: Lucy Sherriff, The Register, December 1, 2004; John Lettice, The Register, March 5, 2004; and various websites

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It’s not the first time that physicists claim that the speed of light can be modified, and even exceed the theoretical limit called c without violating Einstein’s laws of relativity (check for example this article from two years ago). Now, researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland, claim that light can travel faster than light!. They were able to control the speed of light in an off-the-shelf optical fiber. They said that they did “slow a light signal down by a factor of 3.6 (or about 71,000 km/s), creating a sort of temporary “optical memory.” On the other hand, they also did create “extreme conditions in which the light signal travelled faster than 300 million meters a second.” As they don’t give any numbers for this upper limit, you have to trust them. Anyway, these results are important because they were achieved using off-the-shelf optical fibers, opening the way for future super fast all-optical routers. Update (August 22, 2005): Luc Thévenaz sent me insightful comments about this post. You’ll find them at the end of this entry.

So what have done Luc Thévenaz and his fellow researchers in the EPFL’s Nanophotonics and Metrology laboratory (page in French)?

The telecommunications industry transmits vast quantities of data via fiber optics. Light signals race down the information superhighway at about 186,000 miles per second. But information cannot be processed at this speed, because with current technology light signals cannot be stored, routed or processed without first being transformed into electrical signals, which work much more slowly. If the light signal could be controlled by light, it would be possible to route and process optical data without the costly electrical conversion, opening up the possibility of processing information at the speed of light.

This is exactly what the EPFL team has demonstrated. Using their Stimulated Brillouin Scattering (SBS) method, the group was able to slow a light signal down by a factor of 3.6, creating a sort of temporary”optical memory.” They were also able to create extreme conditions in which the light signal travelled faster than 300 million meters a second. And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn’t move over – relativity isn’t called into question, because only a portion of the signal is affected.

Anyway, the real value of this research doesn’t come from light travelling faster than c, but from light travelling slower.

Slowing down light is considered to be a critical step in our ability to process information optically. The US Defense Advanced Research Projects Agency (DARPA) considers it so important that it has been funnelling millions of dollars into projects such as”Applications of Slow Light in Optical Fibers” and research on all-optical routers. To succeed commercially, a device that slows down light must be able to work across a range of wavelengths, be capable of working at high bit-rates and be reasonably compact and inexpensive.

The EPFL team has brought applications of slow light an important step closer to this reality. And Thévenaz points out that this technology could take us far beyond just improving on current telecom applications. He suggests that their method could be used to generate high-performance microwave signals that could be used in next-generation wireless communication networks, or used to improve transmissions between satellites.

The research work has been published by Applied Physics Letters in its August 22, 2005 issue under the name “Optically controlled slow and fast light in optical fibers using stimulated Brillouin scattering” (Volume 87, Issue 8, Article 081113). Here is a link to the abstract which is reproduced below for your convenience.

We demonstrate a method to achieve an extremely wide and flexible external control of the group velocity of signals as they propagate along an optical fiber. This control is achieved by means of the gain and loss mechanisms of stimulated Brillouin scattering in the fiber itself.

Our experiments show that group velocities below 71 000 km/s on one hand, well exceeding the speed of light in vacuum on the other hand and even negative group velocities can readily be obtained with a simple benchtop experimental setup. We believe that the fact that slow and fast light can be achieved in a standard single-mode fiber, in normal environmental conditions and using off-the-shelf instrumentation, is very promising for a future use in real applications.

In this abstract, as in the news release, the researchers give a number for “group velocities” slower than c, but not a single one for those faster than c. I wonder why…

Update (August 22, 2005): Here are Luc Thévenaz’s comments in reaction to the above note, which he nicely allowed me to reproduce.

Most of your comments are right, just be aware that what is really important for applications is delaying and advancing a signal, not the real speed of propagation. This makes possible a synchronisation of optical signals, that was impossible to realize so far with a control by light.

You look very suspicious about our capability to propagate faster than the speed of light in vacuum and you wonder why we mentioned no figure about this. Hmmm, I think you were a bit lazy and you did not read entirely our APL article. The answer is in the 3 last paragraphs, read carefully. We state clearly that we could achieve an infinite and even negative group velocity! We even show a graph of our measurements. We also give explanations why this does not break the principles of relativity and causality in the next paragraph and information still propagates slowlier than the vacuum light velocity.

I just want to mention that what we have just reported experimentally was already predicted theoretically and fully explained during the 1910s by Leon Brillouin and Arnold Sommerfeld. Nothing new and no paradox, there is nothing magic behind and no theory needs to be revisited.

Finally, Luc sent me a copy of the full APL paper. Here is a link to this paper (PDF format, 3 pages, 75 KB).

Sources: EPFL news release, August 19, 2005; and various web sites

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Buried land mines kill more than 15,000 people each year worldwide. At the current removal rate, it will take about 450 years to clear the world of undetected anti-personnel land mines. Many detection methods have been tried, including the use of high-tech ones, such as ground-penetrating radar, infrared imaging, acoustic and seismic methods. But right now, the most common technique is the use of dogs who locate buried land mines through smell. Still, the dogs need to be accompanied by men. And their combined weights can inadvertently cause the explosion of a mine, putting them in constant danger. Now, researchers from several U.S. universities are training honey bees to locate buried land mines through odor detection. Read more…

And this is a very clever idea, which could save many lives. For example, here are some short excerpts from an article from Optics.org, “Honey bees sniff-out landmines.”

Bees do not explode the mines, do not require a handler and can be trained in a couple of days to pick up the scent of the explosive in the landmine.

Jerry Bromenshenk and his colleagues from the University of Montana at Missoula are responsible for training the bees. “By injecting trace amounts of target chemical into feeders, the foraging bees seek sources of food with the same smell. Bees can be trained in one or two days to seek out buried explosives because of their high odor sensitivity in the low parts per trillion range.”

Now, let’s look at another article, “Finding Land Mines by Following a Bee,” from BusinessWeek Online, to discover what bees do after being trained to smell traces of explosives.

After one or two days, the insects naturally become attracted to the smell. When released into a minefield, the bees find their way toward the mines. Of course, they find no actual food, and after lingering disappointedly for a few seconds, they fly off. With thousands of bees flying around, however, scientists have to be able to track these swarms.

But is this method really working?

Bees are too small to detect either with the naked eye or high-resolution video at long ranges. So instead, the team employs a laser emitter that sweeps an area like radar or sonar. When the light hits a bee, it reflects, and sensors are able to tell by the reflection just where the bee is. After sweeping several times, the scientists are able to crunch the data and see statistically where the higher occurrences of bees are located.

In controlled situations, the method is extremely effective: Bees can detect very small traces of explosive vapors with 97% accuracy and are “wrong” — that is, passing over a mine without noticing it — less than 1% of the time.

For more information, the latest research work about bees sniffing for land mines has been published by Optics Express on July 25, 2005 under the name “Polarization lidar measurements of honey bees in flight for locating land mines” (Vol. 13, No. 15, Pages 5853 - 5863).

[Note: LIDAR is an acronym for LIght Detection And Ranging. In fact, Lidar, laser radar, optical radar, and ladar are all names used for "radar" systems utilizing electromagnetic radiation at optical frequencies. FOr more information about lidar systems,please check thes two pages from the NASA web site, here or there.]

Here are the links to the abstract and to the full paper (PDF format, 11 pages, 284 KB).

After reading how bees can help us, I will never look at them as I did before…

Sources: Jacqueline Hewett, Optics.org, August 11, 2005; Burt Helm, BusinessWeek Online, August 16, 2005; and various web sites

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This story could come from the imagination of a screenwriter working on the next James Bond movie, but it’s reality. Japanese physicists have found a way to store data inside your fingernails by using lasers. And, more importantly, they were able to read this data by using an optical microscope. Technology Research News reports that storing data in our fingernails could lead to new ways of authentication. Of course, data is only available for six months. After that the fingernail has grown and the data has disappeared. Still, the researchers think that such a method could have some practical implementations within three years.

Here is the opening of the article.

Researchers from the University of Tokushima and Hokkaido University have demonstrated that it is possible to read data written into a human fingernail using a laser, much like information is written on a rewritable compact disc. The data is read using an optical microscope.

And how does this method work?

[The researchers] wrote dot patterns into a fingernail using a laser that emitted pulses lasting a few million billionths of a second. The molecules of the fingernail that were hit by the laser became ionized, and because ionized molecules repulse each other, they caused a tiny explosion. The explosion changed the structure of the material at that location by decomposing the keratin protein molecules located there. These areas can be read because they fluoresce, or absorb and emit light, at a higher rate than the surrounding fingernail material.

And how much data can they store?

Two gigabits of data can be written per cubic centimeter of fingernail using these size dots. Today’s compact discs hold about 5.6 gigabits of data. A practical fingernail recording area of 5 millimeters by 5 millimeters by one tenth of a millimeter deep would hold 5 megabits of data, or about 300 pages of text.

Of course, this data is secure, at least for the duration of the life of your fingernails.

The researchers’ proof-of-concept samples could still be read 172 days after recording. This is probably the practical limit of fingernail storage because after six months a fingernail has grown enough to be completely replaced.

Will this method for carrying personal data will really be used within three years as are thinking the researchers? I’m not sure.

If you want to learn more about this technology, the latest research work has been published by Optics Express in June 2005 under the title “Three-dimensional optical memory using a human fingernail” (Vol. 13, No. 12, Pages 4560 - 4567, June 13, 2005). Here are two links to the abstract and to the full paper (PDF format, 8 pages, 1.11 MB).

And here are two links to previous papers from 2004 about the same subject, “Optical Bit Recording in a Human Fingernail” and “Processing Structures on Human Fingernail Surfaces Using a Focused Near-Infrared Femtosecond Laser Pulse.”

Sources: Kimberly Patch, Technology Research News, July 27/August 3, 2005; and various web sites

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There are few places outside South Korea where you can today access and transmit data at 100 megabits per second. Now, the Lightwave Architectures for the processing of Broadband Electronic Signals (LABELS) EU-funded project intends to bring data to European homes at speeds of 1 gigabit per second (Gbps). In this article, IST Results writes that Spanish researchers have developed prototypes of optical Internet Protocol (IP) routers. In preliminary tests, which were using the existing fiber-optic infrastructure, they’ve already reached transfer rates of 20 Gbps with these IP routers and hope to reach 40 Gbps soon. If all goes well, this technology will be in your homes within five years.

Here is why the LABELS project was initiated.

“Consumers are soon going to want data streams of 100 megabits per second in their homes and eventually 1 gigabit per second,” says José Capmany, a researcher at Valencia Technical University in Spain and the coordinator of the IST programme-funded project. “There are two ways to do this: lay more cable, which involves public works and is expensive and disruptive, or create technologies that allow existing cable to be used to its utmost potential, which is what we are doing.”

LABELS is developing two key optoelectronic technologies to expand the capacity and speed of fixed-line communications using fibre-optic cables and to improve the processing of radio frequency (RF) signals in wireless networks. Both techniques overcome bottlenecks in the flow of data and, though still in the experimental stage, are proving their potential to vastly improve data flow right along the chain.

Let’s focus only here on the first technology.

In the case of fibre-optic networks, the LABELS project is developing a groundbreaking technique to transmit data faster while using fewer resources. The system is expected to play a role in a future generation of optical Internet Protocol (IP) routers, as opposed to the electronic ones in use today. The major advantage of using light wave architectures for processing is that they can send and receive data over multiple wavelengths as opposed to the single bandwidth that electronic systems are confined to, allowing the full potential of optical networks to be utilised.

The LABELS technique relies on subcarrier multiplexing and label swapping in packet data transfer, allowing nodes at different stages along the network to change the wavelength at which the data is being carried. It is considerably more flexible than existing Wavelength Division Multiplexing (WDM) techniques which, though increasing data transfer speeds, lock signals to specific wavelengths.

And is this multiplexing technique really working and why?

“Existing WDM systems work like a telephone call: you first have to make a connection and then the information is transmitted, which is fine if it is being used for a long duration of time. It is not optimally suited to sending data over the Internet in packets, however, which is precisely what has made IP so successful and which is what we are applying in the optical domain,” Capmany says.

Preliminary tests of the LABELS system, which will be fully evaluated later this year in Valencia, have surpassed even the project’s own goals regarding data transfer rates. “We set out to achieve a rate of 10 Gbps but we saw that we could actually reach 20 Gbps with the current system,” the coordinator notes. “With further development that could even be expanded to 40 Gbps and beyond.”

Still, you’ll have to wait until 2010 before watching a movie with a transfer rate of one gigabit per second.

Finally, if you want more information, here is a link to a page which contains links to several publications about this project.

Source: IST Results, August 3, 2005

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In NASA’s language, a nanosatellite-class system is a small spacecraft, but it is not a nanotechnology-based device. In fact, its new ‘Mini AERCam’ robotic cameras are small, free flying vehicles capable of performing inspection and viewing missions in space. But these spherical-shaped cameras have a diameter of 7.5 inches and weigh about 10 pounds. These cameras are designed to help astronauts and ground crews see outside the spacecraft during a mission. During human space flights, like the ones of the International Space Station (ISS), their use will suppress the need for astronauts to walk in space. And these cameras, tested on the ground today, should be soon deployed in space to watch human-based missions in space. Read more…

Here is the introduction of the NASA’s news release about these small robotic cameras.

Big things can come in small packages, and engineers at NASA’s Johnson Space Center are making progress on a tiny spacecraft that holds major promise for future exploration.

Work on the volleyball-sized Miniature Autonomous Extravehicular Robotic Camera (Mini AERCam) moved forward with successful initial tests on its docking system. The Mini AERCam is designed to help astronauts and ground crews see outside the spacecraft during a mission. During ground-based testing, the device was able to work with the docking system that serves as an exterior home base for housing and refueling the nanosatellite.

So this Mini AERCam is ‘volleyball-sized,’ quite bigger than nanotechnology-based devices according to the ‘official’ definition of nanotechnology — less than 100 nanometers.

Below is a diagram showing the Mini AERCam external features (Credit: NASA).

Two cameras are aligned with the +X direction of the vehicle. One camera provides NTSC-quality color video, and the other camera can be used for high-resolution still images, when selected. A third color video camera is positioned in the +Y direction for an orthogonal view.

And here is an exploded view of the Mini AERCam (Credit: NASA).

The vehicle is designed with a central ring that houses the power and propulsion system. The batteries are lithium-ion and provide six hours of operational time. The propulsion system is designed for cold-gas xenon, which packs more densely than nitrogen, but is compatible with low-cost nitrogen in the current ground test configuration. Attitude and position control are achieved with the use of twelve thrusters, distributed across four thruster pods around the central ring. The batteries are rechargeable and a port is provided for refueling.

Now, let’s go back to the NASA’s news release to discover how these cameras can be deployed in space and docked outside of a bigger spacecraft.

Mini AERCam could be deployed and retrieved many times during a single space mission, with the use of a hangar-based docking system located on the exterior of the vehicle. The free-flyer portion of the docking system includes a vision-based system for autonomous navigation and an electromagnetic capture capability.

For human spaceflights, automatic deployment and docking eliminates the need for astronauts to perform a spacewalk to release and retrieve the free flyer. For robotic missions, external basing is essential. The docking system provides a protective base during periods it is not needed for mission operations.

For even more information, here are two pointers to the Mini AERCam home site and to a technical overview (PDF format, 4 pages, 589 KB). The pictures above were extracted fom this document.

Sources: NASA news release, June 15, 2005; and other NASA sites

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This is the time of the year when pollens give you hay fever and your nose is running like crazy. But now, a new photon-based anti-hay-fever technology is available to help, at least if you live in Central Europe. A small Hungarian company, Rhinolight, has developed a new technology using light cannons to help you. Its special lamps, which illuminate your nose with high energy light, have been installed in about 20 medical centers. After two weeks or about six sessions, the company says that you have a 80% chance to be cured — at least for the current year. But as I haven’t read any reports about the efficiency of this method, don’t book a flight to Budapest before talking to your physician and read more… Update (September 8, 2005): László PÁPAI, the Area Manager from Rhinolight Ltd. sent me new information, and allowed me to publish it. You’ll find it at the bottom of this post.

Let’s start with a warning. All the quotes below come from the Rhinolight website, and I really don’t know if some of their claims are true, even if they’re backed with several scientific publications.

Here is a scary description of hay fever impact today.

Hay fever (allergic fever, allergic rhinitis) is a kind of inflammation of nasal mucosa and nasal sinuses mucosa induced by an allergic reaction.

Allergic rhinitis is the most frequent disease, affecting 10-20% of the population. The frequency of this disease was increasing during last years especially in developed countries. Therefore this century is used to call as the century of allergy.

Hay fever is not a serious disease but troublesome symptoms lower the overall quality of patient’s life. Besides nasal symptoms asthmatic symptoms also develop in 20% of all cases.

Of course, antiallergic drugs exist, but aren’t always efficient or can’t even be used. So (drumroll please!), Rhinolight has developed a new treatment to fight hay fever.

The research group of the Department of Dermatology and Allergology, University of Szeged has evolved the Rhinolight phototherapeutical apparatus, which is suitable for the treatment of the nasal mucosa of patients suffering from allergic rhinitis. The research group has proved that Rhinolight treatment significantly reduces the severity of the clinical symptoms of allergic rhinitis.

What kind of light is used by this device? The company doesn’t give too many details in the page mentioned above.

Rhinolight phototherapy significantly suppresses the symptoms of allergic rhinitis in patients who don’t respond to conventional treatments. The spectrum range of the emitted light is mainly visible light, so it doesn’t have any harmful effects on the nasal mucosa. The ultraviolet range of the emitted light mainly contains ultraviolet A light, which is applicable safely. The UVB spectrum is only 2% of the emitted light, so it has less harmful effects than sunlight. So high energy light source — which contains visible light in 84% — has not been used so far in the treatment of allergic rhinitis.

I’m not sure to understand the above paragraph.

Anyway, be careful before using this device. The idea of having a light cannon pointed to my running nose leaves me somewhat skeptical.

    I am writing as area manager of Rhinolight Ltd., Hungary. I have read Your article on our company and product, and would have a few comments to add.

 

    Firstly, please be advised that the source You have used for preparing your article is out of date, and has not been updated for 2 years. We will soon eliminate this site. By the way, had You clicked on any other links within the site or tried www.rhinolight.hu, You would have seen that there is a web page totally different from that of the one cited in Your article. I am of the opinion that such inaccuracy questions the seriousness of the content any contribution relating to Rhinolight.
    Therefore, contrary to what You have stated, let me set out in particular the issues You have, for yome reason, been mistaken:
1. We have over 60 centers in Hungary, almost 100 including the ones internationally.
2. You claim You have not read anything about efficacy - please do have a look at the list of publications, moreover, read them one by one. Also, You can find the results of a double-bind, randomized, placebo-controlled clinical study on the web page (and in the articles, too). Likewise, we have ongoing studies in Hungary and Switzerland. I assume You have no reason to doubt the trustworthiness of JACI and other prestigious journals, in which we have published these studies.
3. You argue there are not much details specified about the device, then You enlist details. This can also be found on the web-site. However, beyond a certain extent, clearly enough, I suppose, we can not disclose information about the device, it being protected by a patent.
4. You warn your readers to be careful with the “light cannon”. I definitely object to this kind of labelling the Rhinolight III phototherapeutical device - it is engined by a high-discharge tube. Using the word “cannon” suggests something of harmful nature, and anyways, this is not mentioned on the web page. If You have concerns about efficacy and safety, feel free to ask us. We would be happy to provide You with information on the long-term effects - there aren’t any. This is proven by the studies and a comet assay.

 

    I do hope You will consider the abovementioned.

Laser lights can be used for optical sensing applications, for example to identify unknown gases emitted by an engine. And as these unknown substances react differently to different wavelengths, researchers at the University of Wisconsin at Madison have developed unique wavelength-agile lasers. And I’m amazed by the beauty and the simplicity of their idea. They’re using white lasers which produce all colors simultaneously — but with a twist. The white laser light goes through a 20-kilometers long optical fiber before reaching its target. And because different colors ‘travel’ at different speeds, this produces independent results for the different wavelengths. The researchers are using spectral resolutions smaller than a thousandth of a nanometer and they are able to get all the results within a millionth of a second. This method could be used to design cleaner engines or data storage applications in a few years. Read More…

Let’s start with some technical explanations about this technology developed by Professor Scott Sanders in his labs.

Sanders’ laser builds on a phenomenon known as supercontinuum generation, in which researchers convert single-color lasers, such as a green or a red laser, into a multicolored beam using a special kind of optical fiber. Photonic crystal fibers enable them to generate this “white” laser beam, says Sanders.

While that method produces a range of laser colors-and thus, a large amount of information-the drawback is that the white laser delivers all of the colors simultaneously, says Sanders. Rather, researchers want to measure rapidly their subjects’ responses to individual colors.

So by directing the laser through an additional optical fiber about 20 kilometers long, Sanders created what he calls a “color-dependent speed limit.” Although all of colors leave the white laser at the same time, red travels through the fiber more quickly, while blue brings up the rear, and the rest of the colors fall somewhere in the middle. In photographs, they look like a continuous stream; in reality, each color exits the long fiber one after the other, like drops from a faucet. The entire laser scan occurs in a couple of millionths of a second.

Below is a photo showing how UW-Madison engine researchers gather useful data about the gases they study by using these wavelength agile lasers (Credit: UW-Madison College of Engineering).

Here is a link to a higher quality of this picture (3,264 x 2,448 pixels, 5.04 MB).

This research work about ‘rainbow’ lasers is making the cover story of Optics and Photonics News in its May 2005 issue. Full access to the paper (PDF format, 6 pages, 446 KB) is available via this page about “Wavelength-Agile Lasers.”

The figure below, which shows the evolution of wavelength-agile lasers within the author’s laboratory, has been extracted from this article (Credits: UW-Madison College of Engineering and Optics and Photonics News).

These colorful lasers should soon be used in such applications as spectroscopy or high-speed scanning.

Sources: University of Wisconsin at Madison, April 28, 2005; and various websites

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Using a thin film of silver as the lens and ultraviolet (UV) light, scientists at UC Berkeley have built a superlens able to record images with a resolution of 60 nanometers and suitable for integration in today’s optical microscopes which have only a resolution of down to 400 nanometers. Scanning electron and atomic force microscopes can capture detail down to a few nanometers, but they need minutes to take an image, while this new superlens can take snapshots in a fraction of a second. In the short term, this superlens will lead to new nanoscale biomedical imaging devices. But it also can lead to other advances in nanoengineering such as higher density electronic circuitry or faster fiber optic communications systems. Read more…

Let’s start with a brief description of this achievement.

Using a thin film of silver as the lens and ultraviolet (UV) light, the researchers recorded the images of an array of nanowires and the word “NANO” onto an organic polymer at a resolution of about 60 nanometers. In comparison, current optical microscopes can only make out details down to one-tenth the diameter of a red blood cell, or about 400 nanometers.

At top (A) is the higher resolution image of the word NANO created with a silver superlens. Below that (B) is an image created during a control experiment in which the superlens is replaced by spacer layer. The averaged line width is 60 nanometers in image A with the superlens, and 321 nanometer in image B without the superlens. The scale bar in both images is 2 micrometers. (Image by Cheng Sun, UC Berkeley; legend from UC Berkeley).

Here is a link to a larger version (1,500 x 836 pixels, 214 KB).

[And here are the] detailed procedures of obtaining averaged line cross-section profiles (Color Scale 0-50nm): (A) AFM topography of NANO pattern of the recorded image; (B) Zoom-in AFM image of the letter “A”; (C) A further zoomed-in scan for sufficient digitization of individual lines (in this case each pixel measures 3.9nm) (Credit: UC Berkeley).

Here is what one of the scientists says about this superlens.

“The field of optics is involved in much of today’s technology, including imaging and photolithography, which is used to make semiconductors and integrated circuits,” said Xiang Zhang, UC Berkeley associate professor of mechanical engineering and principal investigator of the study. “Our work has a far reaching impact on the development of detailed biomedical imaging, higher density electronic circuitry and ever-faster fiber optic communications.”

The biggest advantage of optical microscopes equipped with this new superlens over scanning electron and atomic force microscopes is the speed at which it can take images.

“Optical microscopes can capture an entire frame with a single snapshot in a fraction of a second,” said Nicholas Fang, [one of Zhang's former Ph.D. students,] who is now an assistant professor of mechanical engineering at the University of Illinois at Urbana-Champaign.

“That opens up nanoscale imaging to living materials, which can help biologists better understand cell structure and function in real time, and ultimately help in the development of new drugs to treat human diseases.”

Besides using this superlens for optical imaging or high-density optoelectronics, these researchers have also long term visions — or dreams.

In the long run, this line of research could lead to even higher resolution imaging for distant objects, the researchers said. This includes more detailed views of other planets as well as of human movement through surveillance satellites.

Now, let’s go down to Earth.

The research work has been published by Science Magazine on April 22, 2005 under the title “Sub-Diffraction-Limited Optical Imaging with a Silver Superlens” (Vol. 308, Issue 5721, Pages 534-537). Here is a link (free registration required) to the abstract which is reproduced below for your convenience.

Recent theory has predicted a superlens that is capable of producing sub–diffraction-limited images. This superlens would allow the recovery of evanescent waves in an image via the excitation of surface plasmons. Using silver as a natural optical superlens, we demonstrated sub–diffraction-limited imaging with 60-nanometer half-pitch resolution, or one-sixth of the illumination wavelength. By proper design of the working wavelength and the thickness of silver that allows access to a broad spectrum of subwavelength features, we also showed that arbitrary nanostructures can be imaged with good fidelity. The optical superlens promises exciting avenues to nanoscale optical imaging and ultrasmall optoelectronic devices.

Finally, please note that the second image on this page has been extracted from the supporting online material for the article mentioned above (PDF format, 12 pages, 564 KB).

Sources: Sarah Yang, University of California at Berkeley news release, April 21, 2005; Science, Vol. 308, Issue 5721, Pages 534-537, April 22, 2005; and various websites

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Physicists from several U.S. labs have clocked the transition of vanadium dioxide nanoparticles from a transparent to a reflective, mirror-like state, at less than 100 femtoseconds (a tenth of a trillionth of a second). According to this Vanderbilt University report, this effect has a size limit: “it does not occur in particles that are smaller than about 20 atoms across (10 nanometers).” This opens the door — if I can say so — to windows that are transparent at low temperatures and block out sunlight when the temperature rises. But other applications are possible, such as nanosensors which could measure the temperature at different locations within human cells, or “ultrafast” optical switches which could be used in communications and optical computing. Read more…

Let’s start with an image which probably took lots of work to its creator, René Lopez.

[Note: the transition from visible to non-visible state of Don Quixote and Sancho Panza is viewable (no punt intended!) from the VU article or directly here (Macromedia Flash format).]

Now, let’s go back to the facts as exposed by the Vanderbilt University (VU) online journal.

How this material (vanadium dioxide or VO2) can turn from a transparent insulator into a reflective metal so rapidly has physicists scratching their heads, but a collaboration among researchers at Vanderbilt, Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory has clocked the transfiguration at one-tenth of a trillionth of a second.

“The change from insulator to metal is called a phase transition,” explains Richard Haglund, a Vanderbilt physics professor. “Phase transitions in solids generally occur at the speed of sound in the material, but vanadium dioxide makes the switch 10 times faster. So far no one has succeeded in coming up with a definitive explanation for that rapid a change.”

But now, the researchers think they have one.

The researchers answered that question by detecting the appearance of a phenomenon called “surface plasmon resonance.” This is a form of electron wave that only occurs on the surfaces of metals and is responsible for the glowing colors of stained glass. Detection of this effect confirmed that vanadium dioxide can switch all the way from transparent to reflective in less than 100 femtoseconds (a tenth of a trillionth of a second).

The new Vanderbilt Institute of Nanoscale Science and Engineering (VINSE) allowed these researchers to go further and to discover that this switch effect had some size limits.

This has allowed them to verify that nanoparticles undergo the same phase transition as thin films. They also have determined that the effect has a size limit: It does not occur in particles that are smaller than about 20 atoms across (10 nanometers). The researchers have established that it is possible to raise and lower the temperature at which the insulator/metal transition takes place by as much as 35 degrees Celsius by adding small amounts of impurities.

And this temperature effect leads to new applications.

It is relatively easy to change the material’s transition temperature to body temperature (98 degrees Fahrenheit; 37 degrees Celsius) by adding precise amounts of impurities. Such doped nanoparticles would be small enough to measure the temperature at different locations within an individual cell and, when injected into the body, could pinpoint hot spots by turning into microscopic mirrors.

Of course, there will be other applications for such a fast ‘phase transition’ effect.

For example, they are exploring whether they can create an “ultrafast” optical switch by putting a layer of vanadium dioxide nanoparticles on the end of an optical fiber. Such a switch could be useful in communications and optical computing.

This research work has been explained in a paper published by Optics Letters in its March 2005 issue under the name “Photoinduced phase transition in VO2 nanocrystals: ultrafast control of surface-plasmon resonance” (Volume 30, Issue 5, 558-560). Here is the text of the abstract.

We study the ultrafast insulator-to-metal transition in nanoparticles of VO2, obtained by ion implantation and self-assembly in silica. The nonmagnetic, strongly correlated compound VO2 undergoes a reversible phase transition, which can be photoinduced on an ultrafast time scale. In the nanoparticles, prompt formation of the metallic state results in the appearance of surface-plasmon resonance. We achieve large, ultrafast enhancement of optical absorption in the near-infrared spectral region that encompasses the wavelength range for optical-fiber communications. One can further tailor the response of the nanoparticles by controlling their shape.

Sources: David F. Salisbury, in Exploration, the online journal of Vanderbilt University, April 6, 2005; and various websites

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We’re all getting older, and many of us will suffer from some alteration of our sense of vision. We might be one day affected by age-related macular degeneration (AMD), which causes blindness to 700,000 people in the Western world every year. But now, ophthalmologists and physicists at Stanford University have teamed up to design a ‘bionic eye’. This system works like some ‘virtual reality’ devices. A little video camera is mounted on transparent goggles allowing for simultaneous use of remaining natural vision. Images from the camera are processed by a microcomputer and projected on the retina. The ‘bionic eye’ which also includes a solar-powered battery implanted in the iris, is currently tested with rats, but human testing could start within three years. Read more…

Here is an excerpt from the introduction of this news release.

[These researchers have designed] an optoelectronic retinal prosthesis system that can stimulate the retina with resolution corresponding to a visual acuity of 20/80 — sharp enough to orient yourself toward objects, recognize faces, read large fonts, watch TV and, perhaps most important, lead an independent life. The researchers hope their device may someday bring artificial vision to those blind due to retinal degeneration.

And here is a description of the problem.

Worldwide, 1.5 million people suffer from retinitis pigmentosa (RP), the leading cause of inherited blindness. In the Western world, age-related macular degeneration (AMD) is the major cause of vision loss in people over age 65, and the issue is becoming more critical as the population ages. Each year, 700,000 people are diagnosed with AMD, with 10 percent becoming legally blind, defined by 20/400 vision. Many AMD patients retain some degree of peripheral vision.

As there is no effective treatment for most patients with AMD and RP, the researchers tried to directly stimulate the inner retina with visual signals.

To that end, the researchers plan to directly stimulate the layer underneath the dead photoreceptors using a system that looks like a cousin of the high-tech visor blind engineer Lt. Geordi La Forge wore in Star Trek: The Next Generation. It consists of a tiny video camera mounted on transparent “virtual reality” style goggles. There’s also a wallet-sized computer processor, a solar-powered battery implanted in the iris and a light-sensing chip implanted in the retina.

The system has been designed by Daniel Palanker and his colleagues of the Group of BioMedical Physics and Ophthalmic Technologies. Here is how it works.

The chip is the size of half a rice grain — 3 millimeters — and allows users to perceive 10 degrees of visual field at a time. It’s a flat rectangle of plastic (eventually a silicon version will be developed) with one corner snipped off to create asymmetry so surgeons can orient it properly during implantation.

The research work has been published by the Journal of Neural Engineering on February 22, 2005 (Volume 2, Number 1, March 2005) under the name “Design of a high-resolution optoelectronic retinal prosthesis.” Here is the end of the abstract, which summarizes how the system works.

To provide for natural eye scanning of the scene, rather than scanning with a head-mounted camera, the system operates similar to ‘virtual reality’ devices. An image from a video camera is projected by a goggle-mounted collimated infrared LED-LCD display onto the retina, activating an array of powered photodiodes in the retinal implant. The goggles are transparent to visible light, thus allowing for the simultaneous use of remaining natural vision along with prosthetic stimulation. Optical delivery of visual information to the implant allows for real-time image processing adjustable to retinal architecture, as well as flexible control of image processing algorithms and stimulation parameters.

And if you need more information, please read the whole well-written news release.

Sources: Dawn Levy, Stanford University News Service, March 30, 2005; and various websites

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Today, we’re using basically two ways to move data in our computers. Transistors carry small amounts of data and are extremely small, while fiber optic cables can carry huge amounts of data, but are much bigger in size. Now, imagine a single technology combining the advantages of photonics and electronics. This Stanford University report says a new technology can do it: plasnomics. (For more about plasmons, read this Wikipedia article.) Theoretically, it is possible to design plasnomic components with the same materials used today by chipmakers, but with frequencies 100,000 times greater than the ones of current microprocessors. There is still a challenge to solve before getting plasnomic chips. Plasmons can only travel a few millimeters before dying while today’s chips are typically about a centimeter across. Read more…

Let’s start with some technical explanations.

Surface plasmons are density waves of electrons — picture bunches of electrons passing a point regularly — along the surface of a metal. Plasmons have the same frequencies and electromagnetic fields as light, but their sub-wavelength size means they take up less space. Plasmonics, then, is the technology of transmitting these light-like waves along nanoscale wires.

“With every wave you can in principle carry information,” says Mark Brongersma, assistant professor of materials science and engineering. [...] “Plasmon waves are interesting because they are at optical frequencies. The higher the frequency of the wave, the more information you can transport.” Optical frequencies are about 100,000 times greater than the frequency of today’s electronic microprocessors.

But let’s get back to the technology.

Plasmons are generated when, under the right conditions, light strikes a metal. The electric field of the light jiggles the electrons in the metal to the light’s frequency, setting off density waves of electrons. The process is analogous to how the vibrations of the larynx jiggle molecules in the air into density waves experienced as sound.

Plasmon waves behave on metals much like light waves behave in glass, meaning that plasmonic engineers can employ all the same ingenious tricks — such as multiplexing, or sending multiple waves — that photonic engineers use to cram more data down a cable.

This sounds good, but is it possible to use this technology today?

Because plasmonic components can be crafted from the same materials chipmakers use today, Stanford engineers are hopeful they can make all the devices needed to route light around a processor or other kind of chip. These would include plasmon sources, detectors and wires, which the lab already has made, as well as splitters and even transistors.

While an all-plasmonic chip might be feasible someday, Brongersma expects that in the near term, plasmonic wires will act as high-traffic freeways on chips with otherwise conventional electronics.

And even Brongersma recognizes that more research needs to be done before getting plasnomic chips.

The potential of plasmonics right now is mainly limited by the fact that plasmons typically can travel only several millimeters before they peter out. Chips, meanwhile, are typically about a centimeter across, so plasmons can’t yet go the whole distance.

The distance a plasmon can travel before dying out is a function of several aspects of the metal. But for optimal transfer through a wire of any metal, the surface of contact with surrounding materials must be as smooth as possible and the metal should not have impurities.

For more information, you can check the following resources.

• “Plasmonic computer chips move closer,” an article published by New Scientist on March 17, 2005
  
  
• The Brongersma Group website and its current research projects
  
  
• The abstract of a presentation given on May 21, 2005 at the March 2005 Meeting of the American Physical Society, “Sub-wavelength confinement and the diffraction limit for surface plasmon waveguides”
  

Sources: David Orenstein, Stanford University Report, March 16, 2005; and various websites

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At Sandia National Laboratories (SNL), researcher Jonathan Weiss, nicknamed the “light wizard,” uses inexpensive soda-straw-like glass tubes for solving a variety of sensing problems. His twelve patents cover areas such as detecting if a car battery is about to die or if dangerous chemical materials are about to escape from a landfill into groundwater. He also developed a sensor which can tell the difference between two liquids in a container. This could be used by oil companies which need to safely determine when to stop pumping oil from the ground before water invades a tank. This market represents about $750 million per year and these sensors should be available in two years according to an interesting story from the Albuquerque Tribune, “Bright Idea: Random chat leads to sensor pact.” Apparently, Weiss found an industrial partner for SNL on a flight between Albuquerque and New York. Read more…

Please read the SNL news release for details about the dead battery problem and the waste detection device through landfills. And let’s focus here on Weiss’s fiber optic sensor that uses light to tell the difference between two liquids in a container.

Imagine you’re in the oil business and you’ve pumped oil and water (just the way it increasingly comes out of the ground) into a holding tank. You want to retrieve only the oil floating atop the water so you can transport the least possible weight from the oil field to a refinery. How do you know — accurately, safely, and simply — when to stop pumping?

Here is the description of Weiss’s solution.

Take two five-foot-long optical fibers made of plastic. Mount them vertically in a tank that holds water with oil on top. Send light down one fiber, and then detect light carried back up by the second fiber. The strength of the detector’s signal depends on the height of the oil/water interface. If the tank is all water, the signal is very strong, and the pumping machine is instructed to stop pumping fluid; there is no oil left.

The Albuquerque Tribune gives more details on why this sensor will be built by Custom Electronics, a New York state company.

When physicists Jonathan Weiss and Allen Anderson, [from Custom Electronics,] met on an airplane, a business opportunity popped out of the quantum mist.

The two didn’t know each other before that flight a year ago, but now Weiss is a Sandia-employed consultant for Anderson’s company, which is working with the lab to license Weiss’ technology.

“My co-worker and I ended up getting separated, and I ended up sitting next to Jonathan and his wife. He told me he was a physicist and I said, hey, I’m a physicist, too,” [said Anderson, the company's director of product development.]

The product could be ready in the next two years according to Anderson. He added that SNL found found a market potential between $250 million and $750 million for the device.

Weiss received a patent in February 2004 for this sensor. You can find technical details on this patent by visiting the United States Patent and Trademark Office and search for patent number 6,693,285.

Here is a direct link to this patent named “Fluorescent fluid interface position sensor.” And here is the abstract.

A new fluid interface position sensor has been developed, which is capable of optically determining the location of an interface between an upper fluid and a lower fluid, the upper fluid having a larger refractive index than a lower fluid. The sensor functions by measurement, of fluorescence excited by an optical pump beam which is confined within a fluorescent waveguide where that waveguide is in optical contact with the lower fluid, but escapes from the fluorescent waveguide where that waveguide is in optical contact with the upper fluid.

Sources: Sandia National Laboratories news release, January 11, 2005; Sue Vorenberg, The Albuquerque Tribune, January 24, 2005; and various websites

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Researchers at Xerox PARC have developed a new way to imbed machine-readable information in printed documents. According to this article from Sci-Tech Today, “Digital Evolution Continues with Xerox Glyphs,” their dataglyphs are composed only of forward (/) or backward () slashes — similar to the zeros and ones used in binary code. These dataglyphs could replace bar codes or be used in faxes, easing the way of routing information in a large company. Xerox is already using these dataglyphs for several projects, including one in Latin America to reduce check fraud. The company also has started an experiment named ‘GlyphSeal’ for two-sided documents, one for human eyes, and the other for machines. Read more…

Here are some quotes from one of the Xerox PARC researchers, Jeff Breidenbach.

“Under a magnifying glass, you can see that a dataglyph is composed of hundreds or thousands of tiny diagonal lines, leaning either forwards or backwards,” said Xerox PARC research scientist Jeff Breidenbach. “Diagonal lines tend to unobtrusively blend — and by varying the color and thickness of these marks, we achieve a lot of aesthetic control.”

“Dataglyphs are essentially a barcode on steroids,” Breidenbach says. “In some ways they are simply more flexible — much more aesthetically flexible, more resistant to certain types of environmental damage, easier to read on curved surfaces, and more flexible in the quantity of data stored — from a handful of bytes to tens of kilobytes.”

You can create and decode your own dataglyphs by running this demonstration.

You’ll find much more information on this technology by reading this technical overview of dataglyphs.

But let’s return to Sci-Tech Today for a description of the ‘GlyphSeal’ experiment ,Breidenbach’s favorite application.

A Xerox experiment, GlyphSeal “is a technique for printing a hybrid analog/digital paper document,” Breidenbach explained. “The front sides of the paper are human readable, while the reverse sides contain a complete machine-readable digital representation. This allows a document to easily travel from computer system to printout and back again.”

The latest research work about GlyphSeal has been published by the Proceedings of SPIE (Volume: 5306, June 2004) under the title “Collocated Dataglyphs for large-message storage and retrieval.” Here is a link to the abstract — a full version in PDF format costs $15. Here is the beginning of the abstract.

In contrast to the security and integrity of electronic files, printed documents are vulnerable to damage and forgery due to their physical nature. Researchers at Palo Alto Research Center utilize DataGlyph technology to render digital characteristics to printed documents, which provides them with the facility of tamper-proof authentication and damage resistance. This DataGlyph document is known as GlyphSeal. Limited DataGlyph carrying capacity per printed page restricted the application of this technology to a domain of graphically simple and small-sized single-paged documents. In this paper the authors design a protocol motivated by techniques from the networking domain and back-up strategies, which extends the GlyphSeal technology to larger-sized, graphically complex, multi-page documents.

Xerox PARC has a long history of good ideas that never been commercially successful — at least for Xerox. Will these dataglyphs become a hit or a flop? Time will tell.

Sources: Mike Martin, Sci-Tech Today, January 21, 2005; and various websites

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Researchers at the University of Toronto (U of T) have designed an infrared-sensitive material made of nanocrystals so small they were able to tune them to catch the Sun’s invisible rays. In “Nanotechnologists’ new plastic can see in the dark,” you’ll discover that it’s the first time that a light-sensitive material works in the invisible light spectrum. This opens the way to a broad range of applications, from clothing to digital cameras that work in the dark. But the real breakthrough is that it will permit to catch five more times energy from the Sun, up to 30 percent from the 6 percent achieved today by the best plastic solar cells. Hats off to these researchers…

Here is the somewhat lyrical opening paragraph of the U of T news release.

Imagine a home with “smart” walls responsive to the environment in the room, a digital camera sensitive enough to work in the dark, or clothing with the capacity to turn the sun’s power into electrical energy. Researchers at the University of Toronto have invented an infrared-sensitive material that could shortly turn these possibilities into realities.

Professor Ted Sargent, from Nortel Networks and U of T, explains the process.

“We made particles from semiconductor crystals which were exactly two, three or four nanometres in size. The nanoparticles were so small they remained dispersed in everyday solvents just like the particles in paint,” explains Sargent. Then, they tuned the tiny nanocrystals to catch light at very short wavelengths. The result — a sprayable infrared detector.

Existing technology has given us solution-processible, light-sensitive materials that have made large, low-cost solar cells, displays, and sensors possible, but these materials have so far only worked in the visible light spectrum, says Sargent. “These same functions are needed in the infrared for many imaging applications in the medical field and for fibre optic communications,” he says.