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Holography
Holography is a technique that enables a wavefront to be recorded and later re-constructed. Holography is best known as a method of generating real three-dimensional images, but it also has a wide range of other applications. In principle, it is possible to make a hologram for any type of wave. A hologram is made by superimposing a second wavefront (normally called the reference beam) on the wavefront of interest, thereby generating an interference pattern which is recorded on a physical medium. When only the second wavefront illuminates the interference pattern, it is diffracted to recreate the original wavefront. Holograms can also be computer-generated by modelling the two wavefronts and adding them together digitally. The resulting digital image is then printed onto a suitable mask or film and illuminated by a suitable source to reconstruct the wavefront of interest. Overview and history The Hungarian- British physicist Dennis Gabor (in Hungarian: ''Gábor Dén ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Holography
Electron holography is holography with electron waves. Dennis Gabor invented holography in 1948 when he tried to improve resolution in electron microscope. The first attempts to perform holography with electron waves were made by Haine and Mulvey in 1952; they recorded holograms of zinc oxide crystals with 60 keV electrons, demonstrating reconstructions with approximately 1 nm resolution. In 1955, G. Möllenstedt and H. Düker invented an electron biprism. thus enabling the recording of electron holograms in off-axis scheme. There are many different possible configurations for electron holography, with more than 20 documented in 1992 by Cowley. Usually, high spatial and temporal coherence (i.e. a low energy spread) of the electron beam are required to perform holographic measurements. High-energy electron holography in off-axis scheme Electron holography with high-energy electrons (80-200 keV) can be realized in a transmission electron microscope (TEM) in an off-axi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer-generated Holography
Computer-generated holography (CGH) is the method of digitally generating holographic interference patterns. A holographic image can be generated e.g. by digitally computing a holographic interference pattern and printing it onto a mask or film for subsequent illumination by suitable coherent light source. Alternatively, the holographic image can be brought to life by a holographic 3D display (a display which operates on the basis of interference of coherent light), bypassing the need of having to fabricate a "hardcopy" of the holographic interference pattern each time. Consequently, in recent times the term "computer-generated holography" is increasingly being used to denote the whole process chain of synthetically preparing holographic light wavefronts suitable for observation. Computer-generated holograms have the advantage that the objects which one wants to show do not have to possess any physical reality at all (completely synthetic hologram generation). On the other hand, if ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Field
The light field is a vector function that describes the amount of light flowing in every direction through every point in space. The space of all possible '' light rays'' is given by the five-dimensional plenoptic function, and the magnitude of each ray is given by its radiance. Michael Faraday was the first to propose that light should be interpreted as a field, much like the magnetic fields on which he had been working. The phrase ''light field'' was coined by Andrey Gershun in a classic 1936 paper on the radiometric properties of light in three-dimensional space. Modern approaches to light field display explore co-designs of optical elements and compressive computation to achieve higher resolutions, increased contrast, wider fields of view, and other benefits. The term “radiance field” may also be used to refer to similar concepts. The term is used in modern research such as neural radiance fields. The plenoptic function For geometric optics—i.e., to incoherent lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dennis Gabor
Dennis Gabor ( ; hu, Gábor Dénes, ; 5 June 1900 – 9 February 1979) was a Hungarian-British electrical engineer and physicist, most notable for inventing holography, for which he later received the 1971 Nobel Prize in Physics. He obtained British citizenship in 1934, and spent most of his life in England. Life and career Gabor was born as Günszberg Dénes, into a Jewish family in Budapest, Hungary. In 1918, his family converted to Lutheranism. Dennis was the first-born son of Günszberg Bernát and Jakobovits Adél. Despite having a religious background, religion played a minor role in his later life and he considered himself agnostic. In 1902, the family received permission to change their surname from Günszberg to Gábor. He served with the Hungarian artillery in northern Italy during World War I. He began his studies in engineering at the Technical University of Budapest in 1918, later in Germany, at the Charlottenburg Technical University in Berlin, now known as t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mieczysław Wolfke
Mieczysław Wolfke (29 May 1883 – 4 May 1947) was a Polish physicist, professor at the Warsaw University of Technology, the forerunner of holography and television. He discovered the method of solidification of helium as well as two types of liquid helium. He was a Masonic Grand Master of the National Grand Lodge of Poland from 1931–1934. He served as President of the Polish Physical Society between 1930–1934. Biography Mieczysław Władysław Wolfke was born on 29 May 1883 in Łask near Łódź. His father, Karol Juliusz Wolfke, was a road engineer. In 1892 Mieczysław and his parents moved to Częstochowa where his father became a district roadside engineer. At the age of 12, Wolfke wrote a dissertation about interplanetary travelling (especially to the Moon). It contained the theory of spaceships driven by the jet force. He also presented scientific hypotheses supported by mathematical models. In Częstochowa Mieczysław completed five years of the gymnasium for boy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
-graphy
The English suffix -graphy means a "field of study" or related to "writing" a book, and is an anglicization of the French ''-graphie'' inherited from the Latin ''-graphia'', which is a transliterated direct borrowing from Greek. Arts * Cartography – art and field of making maps * Choreography – art of creating and arranging dances or ballets * Cinematography – art of making lighting and camera choices when recording photographic images for the cinema. * Collagraphy - In printmaking, a fine art technique in which collage materials are used as ink-carrying imagery on a printing plate. * Iconography – art of interpreting the content by icons. * Klecksography – art of making images from inkblots. * Lithography – planographic printing technique * Photography – art, practice or occupation of taking and printing photographs. * Photolithography – method for microfabrication in electronics manufacturing. * Pornography – practice, occupation and result of producing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rugby, Warwickshire
Rugby is a market town in eastern Warwickshire, England, close to the River Avon. In the 2021 census its population was 78,125, making it the second-largest town in Warwickshire. It is the main settlement within the larger Borough of Rugby which has a population of 114,400 (2021). Rugby is situated on the eastern edge of Warwickshire, near to the borders with Leicestershire and Northamptonshire. Rugby is the most easterly town within the West Midlands region, with the nearby county borders also marking the regional boundary with the East Midlands. It is north of London, east-southeast of Birmingham, east of Coventry, north-west of Northampton, and south-southwest of Leicester. Rugby became a market town in 1255, but remained a small and fairly unimportant town until the 19th century. In 1567 Rugby School was founded as a grammar school for local boys, but by the 18th century it had gained a national reputation as a public school. The school is the birthplace of Rugby ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Writing
Writing is a medium of human communication which involves the representation of a language through a system of physically Epigraphy, inscribed, Printing press, mechanically transferred, or Word processor, digitally represented Symbols (semiotics), symbols. Writing systems do not themselves constitute human languages (with the debatable exception of computer languages); they are a means of rendering language into a form that can be reconstructed by other humans separated by time and/or space. While not all languages use a writing system, those that do can complement and extend capacities of spoken language by creating durable forms of language that can be transmitted across space (e.g. Letter (message), written correspondence) and stored over time (e.g. libraries or other public records). It has also been observed that the activity of writing itself can have knowledge-transforming effects, since it allows humans to externalize their thinking in forms that are easier to reflect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drawing
Drawing is a visual art that uses an instrument to mark paper or another two-dimensional surface. The instruments used to make a drawing are pencils, crayons, pens with inks, brushes with paints, or combinations of these, and in more modern times, computer styluses with graphics tablets or gamepads in VR drawing software. A drawing instrument releases a small amount of material onto a surface, leaving a visible mark. The most common support for drawing is paper, although other materials, such as cardboard, vellum, wood, plastic, leather, canvas, and board, have been used. Temporary drawings may be made on a blackboard or whiteboard. Drawing has been a popular and fundamental means of public expression throughout human history. It is one of the simplest and most efficient means of communicating ideas. The wide availability of drawing instruments makes drawing one of the most common artistic activities. In addition to its more artistic forms, drawing is frequentl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects show a larger parallax than farther objects when observed from different positions, so parallax can be used to determine distances. To measure large distances, such as the distance of a planet or a star from Earth, astronomers use the principle of parallax. Here, the term ''parallax'' is the semi-angle of inclination between two sight-lines to the star, as observed when Earth is on opposite sides of the Sun in its orbit. These distances form the lowest rung of what is called "the cosmic distance ladder", the first in a succession of methods by which astronomers determine the distances to celestial objects, serving as a basis for other distance measurements in astronomy forming the higher rungs of the ladder. Parallax also affects opti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
