TechXplore August 5, 2020 To help individuals inoculate their images against unauthorized facial recognition models, researchers at the University of Chicago have developed a system called Fawkes. It helps individuals add imperceptible pixel-level changes (they call “cloaks”) to their own photos before releasing them. When used to train facial recognition models, the “cloaked” images produce functional models that consistently cause normal images of the user to be misidentified. In experiments Fawkes provided 95+% protection against user recognition regardless of how trackers train their models. They have shown that Fawkes is robust against a variety of countermeasures that try to detect […]
Tag Archives: Imaging technology
Nano-thin flexible touchscreens could be printed like newspaper
Nanowerk January 24, 2020 Researchers in Australia used a thin film common in cell phone touchscreens and shrunk it from 3D to 2D, using liquid metal chemistry. They synthesized flexible two-dimensional indium tin oxide (ITO) using a low-temperature liquid metal printing technique. The approach can directly deposit monolayer or bilayer ITO onto desired substrates, with the resulting bilayer samples offering a transparency above 99.3% and a sheet with low resistance. To illustrate the capabilities of the technique, they developed a capacitive touch screen using centimetre-sized monolayer ITO sheets…read more. TECHNICAL ARTICLE
Portable radiation detectors make the invisible, visible
Physics World August 8, 2019 Traditionally, workers have used hand-held meters to survey small areas methodically, square centimetre by square centimetre. This process is cumbersome, and it can also mean that technicians spend unnecessarily long periods of time in dangerous environments. An international team of researchers (UK, Japan) developed Hot Spot Locator (HSL) that images gamma radiation similar to the way digital cameras image visible light. Signals from an array of high-energy radiation sensors are coupled with a coded aperture, a collection of around a dozen pinholes, which the HCL’s deconvolution algorithms can interpret to create a true image of […]
Closing the terahertz gap: Tiny laser is an important step toward new sensors
EurekAlert July 24, 2019 Current terahertz imaging technologies are expensive to produce and cumbersome to operate. A team of researchers in the US (Princeton University, MIT, University of Notre Dame, Sandia National Laboratory) has demonstrated hyperspectral imaging with chip-scale frequency combs based on terahertz quantum cascade lasers. The dual combs are free-running and emit coherent terahertz radiation that covers a bandwidth of 220 GHz at 3.4 THz with ∼10 μW per line. The combination of the fast acquisition rate of dual-comb spectroscopy with the monolithic design, scalability, and chip-scale size of the combs is highly appealing for future imaging applications in biomedicine […]
Spotting objects amid clutter
MIT News June 19, 2019 State-of-the-art algorithms can sift the bad associations from the good once features have been matched, but it is very slow. With a technique developed by researchers at MIT a robot can see the object through all this clutter and accurately pick out an object, such as a small animal, that is otherwise obscured within a dense cloud of dots, within seconds of receiving the visual data. Their technique prunes away outliers in polynomial time even for increasingly dense clouds of dots. The technique can thus quickly and accurately identify objects hidden in cluttered scenes. They […]
Tiny optical elements could one day replace traditional refractive lenses
Eurekalert March 28, 2019 Metalenses are currently limited by their static and their complex and expensive fabrication and for imaging operations such as zooming and focusing. Most metalenses cannot adjust their focal spots without physical motion as the building blocks of these lenses are made of hard materials that cannot change shape once fabricated. Researchers at Northwestern University built a flat and versatile lens out of an array of cylindrical silver nanoparticles and a layer of polymer patterned into blocks on top of the metal array. By simply controlling the arrangement of the polymer patterns, the nanoparticle array could direct […]
New shapes of laser beam ‘sneak’ through opaque media
Phys.org March 4, 2019 A team of researchers in the US (Yale University, Missouri University of Science & Technology) used a spatial light modulator (SLM) and a CCD camera to analyze an opaque material that is made of a layer of white paint, biological tissue, fog, paper, and milk. The SLM tailors the laser beam incident on the front surface of the material, and the CCD camera records the intensity profiles behind it. The resulting beam was more concentrated, with more light per volume inside and behind the opaque material. The method works for any opaque medium that does not […]
Machines whisper our secrets
UC Riverside News February 22, 2019 Any active machine emits a trace of some form: physical residue, electromagnetic radiation, acoustic noise, etc. A team of researchers in the US (UC Irvine, UC Riverside) set microphones similar to those in a smartphone in several spots near a DNA synthesizer. After filtering out background noise and running several adjustments to the recorded sound, the researchers found the differences were too subtle for humans to notice. But through a careful feature engineering and bespoke machine-learning algorithm they were able to pinpoint those differences. The researchers could easily distinguish each time the machine produced […]
Engineered metasurfaces reflect waves in unusual directions
Nanowerk February 16, 2019 An international team of researchers (Finland, USA – Duke University) introduced purely local reflective metasurfaces for arbitrary manipulations of the power distribution of reflected waves without excitation of any auxiliary evanescent field. The method is based on the analysis of the power flow distribution and the adaptation of the reflector shape to the desired distribution of incident and reflected fields. As a result, they found that these power-conformal metamirrors can be easily implemented with conventional passive unit cells. The results can be used for the design of reflecting surfaces with multiple functionalities and for waves of […]
Improving mid-infrared imaging and sensing
Eurekalert April 26, 2018 Making use of a mid-infrared femtosecond laser coupled with a parametric amplifier, an international team of researchers (MIT, UMass Lowell, China) developed a system that turns regions of molecules in the open air into glowing filaments of plasma. They proved that it did indeed work as expected. It opens the potential for detecting a very wide range of compounds in the air, from a distance. The system can detect various biohazards and pollutants by detecting the exact color of the filament and analyzing the absorption spectrum… read more. Open Access TECHNICAL ARTICLE