Phys.org July 10, 2023 It is possible to observe interference between independent light sources by measuring correlations in their intensities rather than their amplitudes. An international team of researchers (Canada, UK) applied this concept of intensity interferometry to holography. They combined a signal beam with a reference and measured their intensity cross-correlations using a time-tagging single-photon camera. The correlations revealed an interference pattern from which they reconstructed the signal wavefront in both intensity and phase. They demonstrated the principle with classical and quantum light, including a single photon. Since the signal and reference do not need to be phase-stable nor […]
Category Archives: Imaging technology
All-optical, near-infrared imaging via ultra-thin structured films
Phys.org May 26, 2023 Compared to metasurfaces composed of the periodic arrangement of nanoparticles, inverse membrane metasurfaces offer unique possibilities for supporting multipolar resonances, while maintaining small unit cell size, large mode volume and high field enhancement for enhancing nonlinear frequency conversion. An international team of researchers (UK, Australia, China, Hong Kong) theoretically and experimentally investigated the formation of bound states in the continuum (BICs) from silicon dimer-hole membrane metasurfaces, and demonstrated that BIC-formed resonance featured a strong and tailorable electric near-field confinement inside the silicon membrane films. They showed that by tuning the gap between the holes, it is […]
Capturing non-transparent ultrafast scenes
Phys.org May 26, 2023 Real-time imaging modalities with ultrahigh temporal resolutions are required for capturing ultrashort events on picosecond timescales for unveiling many fundamental mechanisms in physics, chemistry, and biology. Current single-shot ultrafast imaging schemes operate only at conventional optical wavelengths, being suitable solely within an optically transparent framework. Researchers in Canada leveraged the unique penetration capability of terahertz radiation to demonstrate a single-shot ultrafast terahertz photography system that could capture multiple frames of a complex ultrafast scene in non-transparent media with sub-picosecond temporal resolution. By multiplexing an optical probe beam in both the time and spatial-frequency domains, they encoded […]
Topologically structured light detects the position of nano-objects with atomic resolution
Phys.org May 19, 2023 Despite recent progress in optical imaging and metrology there remains a substantial resolution gap between atomic-scale transmission electron microscopy and optical techniques. An international team of researchers (UK, Singapore) demonstrated atomic scale metrology by collecting single-shot images of the diffraction pattern of topologically structured light scattered on a suspended nanowire to determine its position relative to the fixed edges of the sample. They trained a deep learning algorithm that could predict the positions of a given nanowire based on the scattered light pattern recorded by the team’s sensor. If a sub-wavelength object moves in such a […]
‘Super-resolution’ imaging technology
Science Daily May 9, 2023 A team of researchers in the US (University of Oklahoma, Yale University) exposed mammalian cells to metallic nanoparticles and then embedded them within different swellable hydrogels to enable quantitative 3D imaging approaching electron-microscopy-like resolution using a standard light microscope. Using the nanoparticles’ light scattering properties, they demonstrated quantitative label-free imaging of intracellular nanoparticles with ultrastructural context and confirmed the compatibility of two expansion microscopy protocols, protein retention and pan-expansion microscopy, with nanoparticle uptake studies. The relative differences between nanoparticle cellular accumulation for various surface modifications were validated using mass spectrometry and determined the intracellular nanoparticle […]
Researchers detect and classify multiple objects without images
Science Daily May 3, 2023 Existing image-free methods still cannot simultaneously obtain the category, location, and size information of all objects. Researchers in China have reported a novel image-free single-pixel object detection (SPOD) technique which enables efficient and robust multi-object detection directly from a small number of measurements, eliminating the requirement for complicated image reconstruction. The small-size optimized pattern sampling method achieved higher image-free sensing accuracy with fewer pattern parameters than convolutional neural network (CNN). Instead of simply stacking CNN layers, they designed the SPOD network based on the transformer architecture. It can better model global features and reinforce the […]
Imaging technique reveals electronic charges with single-atom resolution
Phys.org March 31, 2023 A Kondo lattice is often electrically insulating at low temperatures. However, several recent experiments have detected signatures of bulk metallicity within this Kondo insulating phase. An international team of researchers (USA – Harvard University, University of Illinois, University of Maryland, Stanford University, UK) visualized the real-space charge landscape within a Kondo lattice with atomic resolution using a scanning tunneling microscope. They discovered nanometer-scale puddles of metallic conduction electrons centered around uranium-site substitutions in the heavy-fermion compound uranium ruthenium silicide (URu2Si2) and around samarium-site defects in the topological Kondo insulator samarium hexaboride (SmB6). These defects disturbed the […]
Imaging through random media using coherent averaging
Phys.org March 7, 2023 Although methods to recover the Fourier amplitude through random distortions are well established, recovery of the Fourier phase has been a more difficult problem. Researchers in South Korea proposed and demonstrated a new phase retrieval method for imaging through random media. They showed that by ensemble averaging shift-corrected images, the Fourier phase of an object obscured by random distortions can be accurately retrieved up to the diffraction limit. The method is simple, fast, does not have any optimization parameters, and does not require prior knowledge or assumptions about the sample. The feasibility and robustness of the […]
Single-pulse real-time billion-frames-per-second planar imaging of ultrafast nanoparticle-laser dynamics
Phys.org March 6. 2023 Unburnt hydrocarbon flames produce soot which is the second biggest contributor to global warming. The state-of-the-art high-speed imaging techniques do not provide a complete picture of flame-laser interactions, important for understanding soot formation. An international team of researchers (USA – Caltech, Washington University, Sweden, Germany) has developed single-shot laser-sheet compressed ultrafast photography (LS-CUP) for billion-frames-per-second planar imaging of flame-laser dynamics. They observed laser-induced incandescence, elastic light scattering, and fluorescence of soot precursors – polycyclic aromatic hydrocarbons (PAHs) in real-time using a single nanosecond laser pulse. The spatiotemporal maps of the PAHs emission, soot temperature, primary nanoparticle […]
‘Ghostly’ Glow of Entangled Light Now Reveals Hidden Objects Better Than Ever
Science Alert February 24, 2023 Ghost imaging involves the exploitation of non-local photon spatial correlations to image objects with light that has not interacted with them and, using intelligent spatial scanning with projective masks, reduces detection to a single pixel. Despite many applications, extension to complex amplitude objects remains challenging. Researchers in South Africa revealed that the necessary interference for phase retrieval was naturally embedded in the correlation measurements formed from traditional projective masks in bi-photon quantum ghost imaging. Using this, they developed a simple approach to obtain the full phase and amplitude information of complex objects. They demonstrated straightforward […]