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Axicon
An axicon is a specialized type of lens (optics), lens that has a Cone (geometry), conical surface. An axicon transforms a laser beam into a ring shaped distribution. They can be convex or concave and be made of any optical material. The combination with other axicons or lenses allows a wide variety of beam patterns to be generated. It can be used to turn a Gaussian beam into a non-diffractive Bessel beam, Bessel-like beam. Axicons were first proposed in 1954 by John McLeod. Axicons are used in atomic traps and for generating plasma (physics), plasma in wakefield accelerator, wakefield accelerators. They are used in laser eye surgery, eye surgery in cases where a ring-shaped spot is useful. The Axicon is usually characterized by the ratio of the diameter of the ring to the distance from the lens tip to image plane d/l. Special features and Bessel beam shaping Single axicons are usually used to generate an annular light distribution which is laterally constant along the optical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic and are ground, polished, or molded to the required shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called "lenses", such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices such as telescopes, binoculars, and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from , the Latin name of the lentil (a seed of a lentil pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bessel Beam
Bessel may refer to: Mathematics and science * Bessel beam * Bessel ellipsoid * Bessel function in mathematics * Bessel's inequality in mathematics * Bessel's correction In statistics, Bessel's correction is the use of ''n'' − 1 instead of ''n'' in the formula for the sample variance and sample standard deviation, where ''n'' is the number of observations in a sample. This method corrects the bias in ... in statistics * Bessel filter, a linear filter often used in audio crossover systems * Bessel transform, also known as Fourier-Bessel transform or Hankel transform * Bessel window, in signal processing * Besselian date, see Epoch (astronomy)#Besselian years Places * Bessel Fjord, NE Greenland * Bessel Fjord, NW Greenland * Bessel (crater), a small lunar crater People Surname * Friedrich Wilhelm Bessel (1784–1846), German mathematician, astronomer, and systematizer of the Bessel functions * Johann Franz Bessel (1672–1749), German Benedictine abbot an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Maryland
The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public land-grant research university in College Park, Maryland, United States. Founded in 1856, UMD is the flagship institution of the University System of Maryland. It is known as the biggest university in the state of Maryland. UMD is the largest university in Maryland and the Washington metropolitan area. Its eleven schools and colleges offer over 200 degree-granting programs, including 113 undergraduate majors, 107 master's programs, and 83 doctoral programs. UMD's athletic teams are known as the Maryland Terrapins and compete in NCAA Division I as a member of the Big Ten Conference. A member of the Association of American Universities, The University of Maryland's proximity to Washington, D.C. has resulted in many research partnerships with the federal government; faculty receive research funding and institutional support from many agencies, such as the National In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wendell T
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Wendell may refer to: Places in the United States *Wendell, Idaho *Wendell, Massachusetts *Wendell, Minnesota *Wendell, North Carolina People and fictional characters *Wendell (name), a list of people and fictional characters with the given name or surname *Wendell (footballer, born 1947) (1947–2022), full name Wendell Lucena Ramalho, Brazilian football manager and former goalkeeper *Wendell (footballer, born 1989), full name Wendell Nogueira de Araújo, Brazilian football midfielder *Wendell (footballer, born 1993), full name Wendell Nascimento Borges, Brazilian football left-back *Wendell (footballer, born 2002), full name Wendell Fernandes da Silva, Brazilian football midfielder See also *Wendel (other) Wendel may refer to: People * Wendel (name), including a list of people with the name * Wendel (footballer, born 1981), full name Wendel Santana Pereira Santos, Brazilian football defensive midfielder and wingback * Wendel (footballer, born 1982), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatial Light Modulator
A spatial light modulator (SLM) is a device that can control the intensity, phase, or polarization of light in a spatially varying manner. A simple example is an overhead projector transparency. Usually when the term SLM is used, it means that the transparency can be controlled by a computer. SLMs are primarily marketed for image projection, displays devices, and maskless lithography. SLMs are also used in optical computing and holographic optical tweezers. Usually, an SLM modulates the intensity of the light beam. However, it is also possible to produce devices that modulate the phase of the beam or both the intensity and the phase simultaneously. It is also possible to produce devices that modulate the polarization of the beam, and modulate the polarization, phase, and intensity simultaneously. SLMs are used extensively in holographic data storage setups to encode information into a laser beam similarly to the way a transparency does for an overhead projector. They can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fourier Transform
In mathematics, the Fourier transform (FT) is an integral transform that takes a function as input then outputs another function that describes the extent to which various frequencies are present in the original function. The output of the transform is a complex-valued function of frequency. The term ''Fourier transform'' refers to both this complex-valued function and the mathematical operation. When a distinction needs to be made, the output of the operation is sometimes called the frequency domain representation of the original function. The Fourier transform is analogous to decomposing the sound of a musical chord into the intensities of its constituent pitches. Functions that are localized in the time domain have Fourier transforms that are spread out across the frequency domain and vice versa, a phenomenon known as the uncertainty principle. The critical case for this principle is the Gaussian function, of substantial importance in probability theory and statist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holographic Data Storage
Holographic data storage is a potential technology in the area of high-capacity data storage. While magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium, holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles. Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage. Recording data Holographic data storage contains information using an optical interference pattern within a thick, photosensitive optical material. Light from a single laser beam is divided into two, or more, separate optical patterns of dark and light pixels. By ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Coherence Tomography
Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or other scattering media. It uses interferometry techniques to detect the amplitude and time-of-flight of reflected light. OCT uses transverse sample scanning of the light beam to obtain two- and three-dimensional images. Short-coherence-length light can be obtained using a superluminescent diode (SLD) with a broad spectral bandwidth or a broadly tunable laser with narrow linewidth. The first demonstration of OCT imaging (in vitro) was published by a team from MIT and Harvard Medical School in a 1991 article in the journal ''Science (journal), Science''. The article introduced the term "OCT" to credit its derivation from optical coherence-domain reflectometry, in which the axial resolution is based on temporal coherence. The first demonstrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beckman Laser Institute And Medical Clinic
The Beckman Laser Institute (sometimes called the Beckman Laser Institute and Medical Clinic) is an interdisciplinary research center for the development of optical technologies and their use in biology and medicine. Located on the campus of the University of California, Irvine in Irvine, California, an independent nonprofit corporation was created in 1982, under the leadership of Michael W. Berns, and the actual facility opened on June 4, 1986. It is one of a number of institutions focused on translational research, connecting research and medical applications. Researchers at the institute have developed laser techniques for the manipulation of structures within a living cell, and applied them medically in treatment of skin conditions, stroke, and cancer, among others. History Around 1980, Michael W. Berns, a professor of biology at the University of California, Irvine, founded an institute focusing on the then-new technology of lasers. After receiving a National Institutes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dispersion (optics)
Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. Sometimes the term chromatic dispersion is used to refer to optics specifically, as opposed to wave propagation in general. A medium having this common property may be termed a dispersive medium. Although the term is used in the field of optics to describe light and other electromagnetic waves, dispersion in the same sense can apply to any sort of wave motion such as acoustic dispersion in the case of sound and seismic waves, and in gravity waves (ocean waves). Within optics, dispersion is a property of telecommunication signals along transmission lines (such as microwaves in coaxial cable) or the Pulse (signal processing), pulses of light in optical fiber. In optics, one important and familiar consequence of dispersion is the change in the angle of refraction of different colors of light, as seen in the spectrum produced by a dispersive Prism (optics), prism and in chromatic aberration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatic Aberration
In optics, chromatic aberration (CA), also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the wavelength of light. The refractive index of most transparent materials decreases with increasing wavelength. Since the focal length of a lens depends on the refractive index, this variation in refractive index affects focusing. Since the focal length of the lens varies with the color of the light different colors of light are brought to focus at different distances from the lens or with different levels of magnification. Chromatic aberration manifests itself as "fringes" of color along boundaries that separate dark and bright parts of the image. Types There are two types of chromatic aberration: ''axial'' (''longitudinal''), and ''transverse'' (''lateral''). Axial aberration occurs when different wavelengt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
