A sharper look at the interior of semiconductors

Science Daily  February 17, 2021 To investigate complex, functional, nanoscopic structures of semiconductor devices researchers in Germany have developed an imaging procedure using extreme ultraviolet coherence tomography. It is based on optical coherence tomography used in ophthalmology. They demonstrated the method at a laser-driven broadband extreme ultraviolet radiation source, based on high-harmonic generation. They showed that, besides nanoscopic axial resolution, the spectral reflectivity of all layers in a sample can be obtained using algorithmic phase reconstruction. This provides localized, spectroscopic, material-specific information of the sample. The method can be applied in semiconductor production, lithographic mask inspection, or quality control of multilayer […]

Autofocusing of microscopy images using deep learning

Phys.org  January 25, 2021 Autofocusing is a critical step for high-quality microscopic imaging of specimens, especially for measurements that extend over time covering large fields of view. Hardware-based optical autofocusing methods rely on additional distance sensors that are integrated with a microscopy system; Algorithmic autofocusing methods require axial scanning through the sample volume, leading to longer imaging times, which might also introduce phototoxicity and photobleaching on the sample. Researchers at UCLA have demonstrated a deep learning-based offline autofocusing method, termed Deep-R, that is trained to rapidly and blindly autofocus a single-shot microscopy image of a specimen that is acquired at […]

Optimal information about the invisible

Phys.org  January 25, 2021 If the laser beam is deflected, scattered, and refracted, often it impossible to obtain useful data from the measurement. According to an international team of researchers (the Netherlands, Austria) if you know exactly what the disturbing environment is doing to the light beam, you can reverse the situation: Then it is possible to create a complicated wave pattern instead of the simple, straight laser beam, which gets transformed into exactly the desired shape due to the disturbances and hits right where it can deliver the best result. It is enough to first send a set of […]

Studying chaos with one of the world’s fastest cameras

Science Daily  January 13, 2021 Chaotic systems play a large role in the world around us. They exhibit behavior that is predictable at first but grows increasingly random with time. A team of researchers in the US (Caltech, University of Southern California) designed an ultrafast camera that recorded video at one billion frames per second to observe the movement of laser light in a chamber specially designed to induce chaotic reflections where light takes a different path every time the experiment is repeated. Compressed ultrafast photography (CUP) cameras are capable of speeds as fast as 70 trillion frames per second […]

High-brightness source of coherent light spanning from the UV to THz

Phys.org  December 14, 2020 Hyperspectral spectroscopy and imaging techniques have proven to be very useful in applications related to food inspection, biochemical sensing or even in cultural heritage, to investigate the structure of the materials used for ancient objects, paintings, or sculptures. A standing challenge has been the absence of compact sources that cover such large spectral range with sufficient brightness. An international team of researchers (Spain, Germany, Russia) has developed a compact high-brightness mid-IR-driven source combining a gas-filled anti-resonant-ring photonic crystal fiber with a novel nonlinear-crystal. The tabletop source provides a seven-octave coherent spectrum from 340 nm to 40,000 […]

Engineers combine light and sound to see underwater

Science Daily  November 30, 2020 High-resolution imaging and mapping of the ocean and its floor has been limited to less than 5% of the global waters due to technological barriers. Researchers at Stanford University present a proof-of-concept system which bridges the gap between electromagnetic imaging in air and sonar imaging in water through the laser-induced photoacoustic effect and high-sensitivity airborne ultrasonic detection. They used air-coupled capacitive micromachined ultrasonic transducers which is a critical differentiator from previous works and has enabled the acquisition of an underwater image from a fully airborne acoustic imaging system. There is much promise for the scalability […]

Detecting bacteria with fluorescent nanosensors

Nanowerk  November 25, 2020 Researchers in Germany developed a set of near infrared fluorescent nanosensors are based on single-walled carbon nanotubes that fluoresce in the NIR optical tissue transparency window which offers ultra-low background and high tissue penetration. They are chemically tailored to detect released metabolites as well as specific virulence factors and integrated into functional hydrogel arrays with 9 different sensors. These hydrogels are exposed to clinical isolates of 6 important bacteria and remote (≥25 cm) NIR imaging allows to identify and distinguish bacteria. Sensors are also spectrally encoded to differentiate the two major pathogens P. aeruginosa as well as […]

New technology allows more precise view of the smallest nanoparticles

Science Daily  November 16, 2020 Researchers at the University of Houston have developed a new imaging technology called PANORAMA (PlAsmonic NanO-apeRture lAbel-free iMAging) which uniquely relies on unscattered light to detect sub-100 nm dielectric nanoparticles. It provides diffraction-limited resolution, higher surface sensitivity, and wide-field imaging with dense spatial sampling. Its system is identical to a standard bright-field microscope with a lamp and a camera – no laser or interferometry is needed. In a parallel fashion, PANORAMA can detect, count and size individual dielectric nanoparticles beyond 25 nm, and dynamically monitor their distance to the plasmonic surface at millisecond timescale. The invention […]

The troubling rise of facial recognition technology (podcast; 35 minutes)

Nature Podcast  November 18, 2020 Scientists have grave concerns over ethical and societal impacts of facial-recognition technology. Cities across the globe are installing thousands of surveillance cameras equipped with facial recognition technology. Although marketed to reduce crime, researchers worry that these systems are ripe for exploitation and are calling for strict regulations on their deployment. Despite concerns surrounding consent and use, researchers are still working on facial recognition technology. Nature surveyed 480 researchers who have published papers on facial recognition, AI, and computer science. The results revealed that many researchers think there is a problem.  Podcast

New technology allows cameras to capture colors invisible to the human eye

Phys.org  November 5, 2020 In upconversion imaging phase matching severely limits the spectral bandwidth, therefore requires serial acquisitions to cover a large spectrum. Researchers in Israel have designed an upconversion imaging scheme covering the mid‐IR based on adiabatic frequency conversion. They presented mid‐IR multicolor imaging and demonstrated simultaneous imaging on a CMOS camera of radiation spanning a spectrum from 2 to 4 µm. This approach being coherent and ultrafast in essence, spectrally resolved spatiotemporal imaging is further demonstrated that allows spatially distinguishing the temporal evolution of spectral components. The findings has applications in a variety of fields from computer gaming […]