Science Alert December 4, 2021 Although metasurface optics offer a path to ultra-small imagers, existing methods have achieved image quality far worse than bulky refractive alternatives because of aberrations at large apertures and low f-numbers. A team of researchers in the US (Princeton University, Washington University) has introduced a neural nano-optics imager. They devised a fully differentiable learning framework that learns a metasurface physical structure in conjunction with a neural feature-based image reconstruction algorithm achieving an order of magnitude lower reconstruction error than existing approaches. They experimentally validated the results. The nano-optic imager combines the widest field-of-view for full-color metasurface […]
Category Archives: Imaging technology
New holographic camera sees the unseen with high precision
Science Daily November 17, 2021 A team of researchers in the US (Northwestern University, Southern Methodist University) has invented a new method called synthetic wavelength holography. By capturing the entire light field of an object in a hologram, it is possible to reconstruct the object’s three-dimensional shape in its entirety. They captured holographic imaging around a corner or through scatterers — with synthetic waves instead of normal light waves. From there, an algorithm reconstructed the scattered light signal to reveal the hidden objects. The system could rapidly capture full-field images of large areas with submillimeter precision. To eliminate the need […]
New technique speeds measurement of ultrafast pulses
Science Daily September 24, 2021 Based on the spatio-temporal duality of light pulses, an international team of researchers (USA – University of Rochester, China, Canada) has developed a time-domain single-pixel imaging technique that detects 5 femtojoule ultrafast light pulses with a temporal sampling size down to 16 femtoseconds. The technique can also be combined with single-pixel imaging to create a computational hyperspectral imaging system. The system can greatly speed up the detection and analysis of images at broad frequency bands which could be especially useful for medical applications. According to the researchers by coupling their technique with single pixel imaging […]
New quantum ‘stopwatch’ can improve imaging technologies
Phys.org August 24, 2021 Time-correlated single-photon counting (TCSPC) is an enabling technology for applications such as low-light fluorescence lifetime microscopy and photon counting time-of-flight (ToF) 3D imaging. However, state-of-the-art TCSPC single-photon timing resolution (SPTR) is limited to 3–100 ps by single-photon detectors. Researchers at the University of Colorado experimentally demonstrated a time-magnified TCSPC (TM-TCSPC) that achieves an ultrashort SPTR of 550 fs with an off-the-shelf single-photon detector. It can resolve ultrashort pulses with a 130-fs pulse width difference at a 22-fs accuracy. When applied to photon counting ToF 3D imaging, the it greatly suppresses the range walk error that limits […]
Engineers bend light to enhance wavelength conversion
Nanowerk July 30, 2021 Incoming light can hit the electrons in the semiconductor lattice and move them to a higher energy state creating an electric field which further accelerates the high-energy electrons. They unload the extra energy by radiating it at different optical wavelengths, thus converting the wavelengths. An international team of researchers (USA – UCLA, Iowa State University, Germany) devised a solution for improving wavelength conversion using the semiconductor surface state phenomenon. They incorporated a nanoantenna array that bends incoming light, so it is confined around the shallow surface of the semiconductor converting the wavelength easily and without any […]
Method uses radio signals to image hidden and speeding objects
Phys.org June 25, 2021 Light-in-flight sensing has emerged as a promising technique in image reconstruction applications at various wavelengths. A team of researchers in the US (NIST, industry, University of Colorado) has developed a microwave imaging system that uses an array of transmitters and a single receiver operating in continuous transmit-receive mode. Captures take a few microseconds, and the corresponding images cover a spatial range of tens of square meters with spatial resolution of 0.1 meter. The images are the result of a dot product between a reconstruction matrix and the captured signal with no prior knowledge of the scene. […]
Optical superoscillation without side waves
EurekAlert June 24, 2021 Optical superoscillation refers to a phenomenon of a wave packet that can oscillate locally faster than its highest Fourier component, which potentially produces an extremely localized wave in the far field. It provides an alternative way to overcome the diffraction limit and improve the resolution of an optical microscopy system. However, the optical superoscillatory waves are inevitably accompanied by strong side lobes, which limits their fields of view and, hence, potential applications. Researchers in China report both experimentally and theoretically a new superoscillatory wave form, which not only produces significant feature size down to deep subwavelength, […]
Cameras and telescopes as thin as a sheet of paper?
Nanowerk June 10, 2021 Metalenses promise to make imaging devices more compact. An international team of researchers (Canada, USA – University of Rochester) has addressed the space between the lenses which is crucial for image formation but takes up by far the most room in imaging systems, by introducing the idea of a spaceplate. They experimentally demonstrated that it is compatible with broadband light in the visible spectrum. They manipulated light based on the angle rather than the position of a light ray. Angle is a completely novel domain. They designed and experimentally demonstrated plates that compressed the space. Such […]
Let there be light! New tech allows people to see in the dark
Nanowerk June 10, 2021 Conventional infrared imaging technologies require the use of materials such as narrow bandgap semiconductors, which are sensitive to thermal noise and often require cryogenic cooling. An international team of researchers (Australia, Italy, UK, Germany, France, Bulgaria) developed and demonstrated a proof-of-concept compact all-optical device to perform infrared imaging in a metasurface composed of GaAs semiconductor nanoantennas using a nonlinear wave-mixing process. Experimentally they showed the upconversion of short-wave infrared wavelengths via the coherent parametric process of sum-frequency generation. In this process, an infrared image of a target is mixed inside the metasurface with a strong pump […]
Researchers create quantum microscope that can see the impossible
Phys.org June 9, 2021 The performance of light microscopes is limited by the stochastic nature of light. Randomness in the times that photons are detected introduces shot noise, which fundamentally constrains sensitivity, resolution, and speed. Although the long-established solution to this problem is to increase the intensity of the illumination light, this is not always possible when investigating living systems, because bright lasers can severely disturb biological processes. An international team of researchers (Australia, Germany) has experimentally shown that quantum correlations allow a signal-to-noise ratio beyond the photodamage limit of conventional microscopy. They developed a coherent Raman microscope that offers […]