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Superoscillation
Superoscillation is a phenomenon in which a signal which is globally band-limited can contain local segments that oscillate faster than its fastest Fourier components. The idea is originally attributed to Yakir Aharonov, and has been made more popularly known through the work of Michael Berry, who also notes that a similar result was known to Ingrid Daubechies. In 2007, Huang experimentally observed optical superoscillation phenomenon in the diffraction patterns of light transmitted through quasi-periodic nanohole arrays. Optical foci much smaller than the diffraction limit were observed. The results matched simulations without evanescent waves. In 2009, Huang et al further developed theoretical models to design superoscillation masks that can achieve extreme light concentration and imaging with arbitrary resolution. A practical method for constructing superoscillations and a discussion of their potential for quantum field theory were given by Achim Kempf. Chremmos and Fikioris hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michael Berry (physicist)
Sir Michael Victor Berry, (born 14 March 1941), is a mathematical physicist at the University of Bristol, England. He is known for the Berry phase, a phenomenon observed e.g. in quantum mechanics and optics, as well as Berry connection and curvature. He specialises in semiclassical physics (asymptotic physics, quantum chaos), applied to wave phenomena in quantum mechanics and other areas such as optics. Education and early life Berry was brought up in a Jewish family and was the son of a London taxi driver and a dressmaker. Berry has a BSc in physics from the University of Exeter and a PhD from the University of St. Andrews. Career and research He has spent his whole career at the University of Bristol: research fellow, 1965–67; lecturer, 1967–74; reader, 1974–78; Professor of Physics, 1978–88; Royal Society Research Professor 1988–2006. Since 2006 he is Melville Wills Professor of Physics (Emeritus) at Bristol University. Publications *''Diffraction of Light by Ul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Superresolution
Super-resolution imaging (SR) is a class of techniques that enhance (increase) the resolution of an imaging system. In optical SR the diffraction limit of systems is transcended, while in geometrical SR the resolution of digital imaging sensors is enhanced. In some radar and sonar imaging applications (e.g. magnetic resonance imaging (MRI), high-resolution computed tomography), subspace decomposition-based methods (e.g. MUSIC) and compressed sensing-based algorithms (e.g., SAMV) are employed to achieve SR over standard periodogram algorithm. Super-resolution imaging techniques are used in general image processing and in super-resolution microscopy. Basic concepts Because some of the ideas surrounding super-resolution raise fundamental issues, there is need at the outset to examine the relevant physical and information-theoretical principles: * Diffraction limit: The detail of a physical object that an optical instrument can reproduce in an image has limits that are mandated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band-limited
Bandlimiting is the limiting of a signal's frequency domain representation or spectral density to zero above a certain finite frequency. A band-limited signal is one whose Fourier transform or spectral density has bounded support. A bandlimited signal may be either random (stochastic) or non-random ( deterministic). In general, infinitely many terms are required in a continuous Fourier series representation of a signal, but if a finite number of Fourier series terms can be calculated from that signal, that signal is considered to be band-limited. Sampling bandlimited signals A bandlimited signal can be fully reconstructed from its samples, provided that the sampling rate exceeds twice the maximum frequency in the bandlimited signal. This minimum sampling rate is called the Nyquist rate. This result, usually attributed to Nyquist and Shannon, is known as the Nyquist–Shannon sampling theorem. An example of a simple deterministic bandlimited signal is a sinusoid of the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fourier Component
A Fourier transform (FT) is a mathematical transform that decomposes functions into frequency components, which are represented by the output of the transform as a function of frequency. Most commonly functions of time or space are transformed, which will output a function depending on temporal frequency or spatial frequency respectively. That process is also called ''analysis''. An example application would be decomposing the waveform of a musical chord into terms of the intensity of its constituent pitches. The term ''Fourier transform'' refers to both the frequency domain representation and the mathematical operation that associates the frequency domain representation to a function of space or time. The Fourier transform of a function is a complex-valued function representing the complex sinusoids that comprise the original function. For each frequency, the magnitude (absolute value) of the complex value represents the amplitude of a constituent complex sinusoid with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yakir Aharonov
Yakir Aharonov ( he, יקיר אהרונוב; born August 28, 1932) is an Israeli physicist specializing in quantum physics. He has been a Professor of Theoretical Physics and the James J. Farley Professor of Natural Philosophy at Chapman University in California since 2008. He is also a distinguished professor in the Perimeter Institute and a professor emeritus at Tel Aviv University in Israel. He is president of the IYAR, The Israeli Institute for Advanced Research. Biography Yakir Aharonov was born in Haifa. He received his undergraduate education at the Technion – Israel Institute of Technology in Haifa, graduating with a BSc in 1956. He continued his graduate studies at the Technion and then moved to Bristol University, UK together with his doctoral advisor David Bohm, receiving a Ph.D. degree in 1960. Aharonov later taught at the Brandeis University from 1960–61 and the Yeshiva University from 1964–67, both in the United States. Academic career His research interest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ingrid Daubechies
Baroness Ingrid Daubechies ( ; ; born 17 August 1954) is a Belgian physicist and mathematician. She is best known for her work with wavelets in image compression. Daubechies is recognized for her study of the mathematical methods that enhance image-compression technology. She is a member of the National Academy of Engineering, the National Academy of Sciences and the American Academy of Arts and Sciences. She is a 1992 MacArthur Fellow. She also served on the Mathematical Sciences jury for the Infosys Prize from 2011 to 2013. The name Daubechies is widely associated with the orthogonal Daubechies wavelet and the biorthogonal CDF wavelet. A wavelet from this family of wavelets is now used in the JPEG 2000 standard. Her research involves the use of automatic methods from both mathematics, technology, and biology to extract information from samples such as bones and teeth. She also developed sophisticated image processing techniques used to help establish the authenticity and ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achim Kempf
Achim (; Northern Low Saxon: ''Achem''), commonly Achim bei Bremen, is a municipality and the largest town (population 30,059 in December 2006) in the district of Verden, in Lower Saxony, Germany. It is situated on the right bank of the Weser, approx. 17 km northwest of Verden, and 16 km southeast of Bremen. Geography Achim lies in the Weser Depression, an Urstromtal. The area surrounding Achim is primarily moorland in its natural state. It has an elevation between 12 and 40 metres above sea level, and an area of 65.1 km2. For the Badener mountains and Oil Camp, see Baden, Lower Saxony. History The first recorded mention of Achim came in 1091 as Arahem. The controlling heights of the Linden Mountains, south of Bremen, on which the old Arahem leaned, was a cult- and court-location. Achim was a meeting place of old Saxon courts. The court met three times annually. The Christian missionaries erected a baptismal church in Achim in the 12th century; it was the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nyquist Rate
In signal processing, the Nyquist rate, named after Harry Nyquist, is a value (in units of samples per second or hertz, Hz) equal to twice the highest frequency (bandwidth) of a given function or signal. When the function is digitized at a higher sample rate (see ), the resulting discrete-time sequence is said to be free of the distortion known as aliasing. Conversely, for a given sample-rate the corresponding Nyquist frequency in Hz is one-half the sample-rate. Note that the ''Nyquist rate'' is a property of a continuous-time signal, whereas ''Nyquist frequency'' is a property of a discrete-time system. The term ''Nyquist rate'' is also used in a different context with units of symbols per second, which is actually the field in which Harry Nyquist was working. In that context it is an upper bound for the symbol rate across a bandwidth-limited baseband channel such as a telegraph line or passband channel such as a limited radio frequency band or a frequency division mult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
