A repository & source of cutting edge news about emerging terahertz technology, it's commercialization & innovations in THz devices, quality & process control, medical diagnostics, security, astronomy, communications, applications in graphene, metamaterials, CMOS, compressive sensing, 3d printing, and the Internet of Nanothings. NOTHING POSTED IS INVESTMENT ADVICE! REPOSTED COPYRIGHT IS FOR EDUCATIONAL USE.
This paper presents imaging and analysis of heterogeneous breast cancer tissue using pulsed terahertz (THz) imaging technology. The goal of this research is to validate and standardize a methodology for THz imaging capable of differentiating between heterogeneous regions of breast tumors. The specimens utilized here were obtained from breast tumors diagnosed as triple negative infiltrating ductal carcinoma (IDC). These tissues were fixed in formalin, embedded in paraffin, and cut into sections of three thicknesses: 10, 20, and 30 μm. All tissues were prepared on standard glass slides used in regular histopathology of hematoxylin and eosin (H&E) stained sections. The THz pulsed system is used to scan the two dimensional tissue sections with step size of 400, 200, and 50 μm. The experimentally measured THz fields reflected from single pixels identified in each region of the tumor are validated with the Fresnel reflection coefficient formulation. A variety of signal normalization and processing methods are investigated. The images are also validated with the standard histopathology images. The obtained results of three different tumors demonstrate strong capability of THz reflection imaging mode to distinguish between the heterogeneous regions in the tumor.
The realization of high refractive index is of significant interest in optical imaging with enhanced resolution. Strongly coupled subwavelength resonators were proposed and demonstrated at both optical and terahertz frequencies to enhance the refractive index due to large induced dipole moment in meta-atoms. Here, we report an alternative design for flexible free-standing terahertz metasurface in the strong coupling regime where we experimentally achieve a peak refractive index value of 14.36. We also investigate the impact of the nearest neighbor coupling in the form of frequency tuning and enhancement of the peak refractive index. We provide an analytical circuit model to explain the impact of geometrical parameters and coupling on the effective refractive index of the metasurface. The proposed meta-atom structure enables tailoring of the peak refractive index based on nearest neighbor coupling and this property offers tremendous design flexibility for transformation optics and other index-gradient devices at terahertz frequencies.
Dirac-like electrons in solid state have been of great interest since they exhibit many peculiar physical behaviors analogous to relativistic mechanics. Among them, carriers in graphene and surface states of topological insulators are known to behave as massless Dirac fermions with a conical band structure in the two-dimensional momentum space, whereas electrons in semimetal bismuth (Bi) are expected to behave as massive Dirac-like fermions in the three-dimensional momentum space, whose dynamics is of particular interest in comparison with that of the massless Dirac fermions. Here, we demonstrate that an intense terahertz electric field transient accelerates the massive Dirac-like fermions in Bi from classical Newtonian to the relativistic regime; the electrons are accelerated approaching the effective “speed of light” with the “relativistic” beta β = 0.89 along the asymptotic linear band structure. As a result, the effective electron mass is enhanced by a factor of 2.4.
This paper describes the basic design, implementation, and testing of a polarization difference imaging system for use on aqueous targets. The ultimate performance limitation of THz imaging in many active areas of research is clutter from surface geometry. While the signal to nose ratio (SNR) of standard THz imaging systems is quite large, the signal to clutter ratio (SCR) often faced in an imaging application is orders of magnitude lower and, in many cases, lower than the contrast to noise (CNR) resulting in imagery where the contrast mechanism of interest does not significantly contribute to the overall observed contrast. To overcome these limitations we develop a system that uses a circularly polarized source and linearly polarized detectors to acquire images of transverse electric (TE) and transverse magnetic (TM) reflectivities of the target over the same field of view. Geletin based tissue mimicking phantoms are fabricated with spatially varying water content and modified with a range of surface topologies and surface roughness. TE and TM images are combined to yield self-calibrated clutter-suppressed images. The resulting image indicates that the imaging field clutter affected both polarization channels nearly equally allowing the system to resolve differences in phantom water content. This design is a step toward windowless THz imaging capability critical for clinical translation where patient imaging is dominated by clutter.
We report on terahertz (THz) emission from a (111)-cut InAs crystal in the reflection and transmission directions, excited by femtosecond optical pulses in the direction of its surface normal. THz pulse amplitudes emitted from the crystal surface in this case were only ∼20% smaller than for optimal photoexcitation at a 45° angle. This observation evidences that THz emission from InAs is caused by lateral photocurrent transients appearing due to a crystal anisotropy rather than directly by the photo-Dember effect, which creates fast changing electric polarization perpendicular to the surface. Such a simple geometry of the photoexcitation could greatly enhance the fields of surface THz emitter applications.
Going through security at an airport and being checked by a walk-in body scanner could soon become a thing of the past.
Instead, a special camera would be used with a sensor that records images of what’s beneath a person's clothes. A silhouette of a concealed weapon would appear in the image.
This technology being developed by Harris Corp., which could potentially take pictures of anyone at an airport, is at least a few years away from being implemented. And it requires researchers with an expertise in optics, photonics and imaging science.
That’s where the University of Rochester’s Center for Emerging and Innovative Sciences has stepped in.
Serving as a high-tech matchmaker, the center has not only provided about $350,000 over four years for this project but has also lined up scientists with the needed skills from UR and Rochester Institute of Technology to help Harris, which has put in about $750,000.
“The idea is to make a camera and stand back 30 feet and snap a picture,” said Mark Bocko, the center's director.
With the center recently being awarded a $9.2 million grant over the next decade from the Empire State Development, the collaborations will continue. The Harris project is one of about 20 that the center nurtures each year.
Designed to bring academia and business together, the center is best known for its work in helping companies in the field of optics, photonics and imaging science — disciplines that UR and RIT have long been at the forefront.
"We try to solve problems companies bring to us and find university researchers to assist them," said Bocko, who also chairs the electrical and computer engineering department.
Another company being helped by the center is Optipro Systems in Ontario, Wayne County. In this match, Jonathan Ellis, an assistant professor of optics and mechanical engineering, and some of his graduate students are developing a probe piece that can correct imperfections in glass used for various lenses.
In still another match, a local startup firm, Clerio Vision, is being helped by the center in developing a laser technology that could correct such eye problems as near-sightedness without surgery.
UR and RIT faculty do not only apply their skills but also give their graduate students needed experience.
"There is a huge value in connecting researchers with real needs," said Wendi Heinzelman, who is dean of graduate studies at UR and a professor of electrical and computer engineering.
Helping Harris
With the camera being developed, Harris is working with university researchers who have an expertise in terahertz waves — electromagnetic waves that can penetrate clothes, luggage, plastics and many other materials that don't conduct electricity.
The terahertz camera is accompanied by a device that creates and aims terahertz waves. Since these waves cannot penetrate metal, a concealed weapon would bounce them back to the camera. Unlike a typical digital camera, the terahertz camera creates an image of the weapon on its sensor in a silicon chip.
Daniel Newman, Harris' manager for this project who is based in Rochester, said it would be much more expensive if the company had to develop this product on its own. The project began with the center helping Exelis, which was bought by Harris in June.
Four UR scientists and one from RIT, along with four graduate students at both colleges, are working with Harris on this project.
Zeljko Ignjatovic, an associate professor of electrical and computer engineering at UR, is working with Zoran Ninkov, professor of imaging science at RIT, to develop a sensor. Assisted by others on the team, they have already made a prototype camera for recording terahertz waves.
"There is a huge market besides just looking for guns," Ninkov said.
The camera could be used for various quality control checks in manufacturing because it could provide a look into what's inside most containers. It could also be used to help detect skin cancer at an early stage because the terahertz waves bounced back by cancer cells would be different from the rest of the reflected waves.
Water in a human body absorbs some of the terahertz waves, but the outlines of genitals and breasts would also appear on the sensor, but could be made into faint images if computer software was used to do so, said Ignjatovic.
"The sensors will see everything, but what the camera will capture you have control over," he said.
Unlike X-rays, terahertz waves do not ionize, which can cause chemical changes in tissue. But more research needs to be done on long-term effects.
"At first glance, it's easy to dismiss any notion that they can be damaging. Terahertz photons are not energetic enough to break chemical bonds or ionize atoms or molecules," said a 2009 MIT Technology Review article.
But the article goes on to say that the "evidence terahertz radiation damages biological systems is mixed."
Center's record
Established in 1993 as the Center for Electronic Imaging Systems, the center underwent a name change in 2008 to better fit its mission.
But all along, the center has connected researchers with the needs of businesses on particular projects. The center usually puts up a third of the funding and the business foots the rest. Most of the funds that the colleges receive go to supporting the graduate students.
Over the past decade, the UR center has provided funding for almost 300 projects, usually helping a company needing high-tech expertise to develop a product.
The economic impact of this spending, according to the center's latest annual report, was about $700 million, much of it being in increased revenues but also including about 200 new jobs.
Companies helped must be located in New York or do a significant amount of business in the state. They are typically part of the emerging photonics, optics and imaging sciences sector.
The center exemplifies the kind of partnership between colleges and businesses that is supposed to advance the local economy in the digital age.
Thomas Bifano, director of the photonics center at Boston University, said UR’s matchmaking efforts are happening across the country.
Other universities — including Stanford, Duke, Arizona and Central Florida — have photonics researchers working with local companies, Bifano said, but "Rochester has been at the forefront of that for many, many years."
The director said there’s likely more activity at other universities coming soon regarding photonics researchers and companies.
"As long as the university has a good system for promoting the connection and they protect the intellectual property with patents, universities can be a really fertile environment for new discoveries," he said.
Dating to the establishment of its Institute of Optics in 1929, UR has been a major player in producing top-notch talent in optics — the science of using light to perform functions previously done by electrical circuits.
The silicon chips that often carry out the functions of optics and photonics can process and move massive amounts of information much faster than electrical circuits.
Photonics researchers paired with optics and photonics businesses is a setup that'll happen much more often next year. Rochester was designated the operations and manufacturing headquarters for a $600 million federal initiative on photonics.
When the center expects to open in January, top scientists in the field will begin working on projects for the U.S. Department of Defense. New York businesses have pitched in part of a $250 million chunk of this funding. They expect some of the photonics researchers to work with them on new products and services.
Bocko, who has served as the center’s director since 2010, and his executive director, Paul Ballentine, helped lay the groundwork for the federal government designating Rochester as the headquarters of the $600 million initiative this past July.
They did so by getting UR or Rochester designations for grants or programs promoting photonics. That happened in three instances, and beginning in 2012 when the center was awarded a $2.6 million federal grant to bring together UR, RIT, Monroe Community College, High Tech Rochester and the Rochester Regional Photonics Cluster.
New applications of technology
Other projects — matches between companies and university researchers — show how the center, which originally worked mostly with large companies such as Eastman Kodak Co., has extended its reach to smaller high-tech firms.
Optipro Systems needed UR expertise in optics and photonics.
The company makes and sells machines that other companies can use to grind, polish and finish glass.
This glass is made into carefully crafted lenses for movie cameras, microscopes, telescopes, satellites and other uses. In order for the lens to work well, Optipro machines must shave off extremely thin layers of glass, down to the micron level.
Mike Bechtold, Optipro president, said manually working with glass that has been shaved will oftentimes damage the piece.
"You can scratch it by having anything touch it," he said. "A piece of tissue can scratch it."
To solve the problem, the company has been paired with UR’s Ellis, who has a background in optics and mechanical engineering, to develop a part for Optipro that can examine imperfections on a piece of glass without anyone having to touch it.
Ellis and his team of graduate students have been working on this probe piece for about two years, Bechtold said, adding that he thinks Ellis is close to finishing it.
Optipro is spending $139,000 to fund Ellis' research. UR has contributed $60,000 over two years.
By adding this probe piece, Bechtold said his company can sell machines that will make little to no mistakes when making that perfect sheet of glass.
“When you don’t have to touch it, it’s a big deal,” he said.
In helping Clerio Vision, the center is trying to assist a startup that emerged after Bausch + Lomb was bought by Valeant Pharmaceuticals.
Ballentine, executive director of the center, said that Valeant was pulling back from research and, as a result, UR researchers with the help of investors stepped in.
They are developing a new laser that — without surgery — can change the cornea’s ability to bend light and fix vision problems, such as near- and far-sightedness and astigmatism.
Researchers assembled by the center believe the device they are developing has the potential of eliminating the need for eyeglasses and contact lenses.
Sasha Latypova, the company’s executive vice president, said she believes patients would opt for this corrective technique because it would offer a safer and easier way to fix their eyesight.
The company is spending $1.4 million over a two-year period and working with three UR researchers: Wayne Knox, Krystel Huxlin and Ellis.
Knox is in charge of determining the wavelength, power and repetition of the laser going into an eye. Huxlin is leading current animal testing and will head the human testing trials in the future. Ellis will work on the actual mechanics and movement of the laser.
Clerio Vision CEO Alex Zapesochny said the company is still five to eight years away from finishing this laser. However, once it’s finished, he wants to sell the lasers to optometrists.
“If it works, it’ll be a lot of jobs in Rochester,” Ballentine said.
