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Lieberkühn Reflector
A Lieberkühn reflector (also known as Lieberkühn mirror or simply Lieberkühn) is an illumination device for incident light illumination (epi-illumination) in light microscopes. It encircles the objective (optics), objective, with the mirrored surface facing towards the specimen. This allows illuminating an opaque object from the side of the objective, with the light source positioned behind the specimen as in a transmission microscope. The device is named after Johann Nathanael Lieberkühn (1711–1756) who used and popularized it but did not invent it. Similar mirrors were described and used by earlier microscopists. Operation and Light Path The principle is explained for a modern upright compound microscope, where the light source illuminates the specimen from below. The light passes the object of interest laterally upwards. When using the Lieberkühn reflector, the opening in the microscope stage is covered with a flat glass plate upon which the specimen is placed. Typic ... [...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] |
Charles Chevalier
Charles is a masculine given name predominantly found in English and French speaking countries. It is from the French form ''Charles'' of the Proto-Germanic name (in runic alphabet) or ''*karilaz'' (in Latin alphabet), whose meaning was "free man". The Old English descendant of this word was '' Ċearl'' or ''Ċeorl'', as the name of King Cearl of Mercia, that disappeared after the Norman conquest of England. The name was notably borne by Charlemagne (Charles the Great), and was at the time Latinized as ''Karolus'' (as in ''Vita Karoli Magni''), later also as '' Carolus''. Etymology The name's etymology is a Common Germanic noun ''*karilaz'' meaning "free man", which survives in English as churl (James (< Latin ''-us'', see Spanish/ Portuguese ''Carlos''). According to Julius Pokorny, the historical linguist and Indo-European studies, Indo-Europeanist, the root meaning of Charles is "old man", from Proto-Indo-European language, Indo-European *wikt:Appendix:Proto-Indo-Eur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georg Friedrich Brander
Georg Friedrich Brander (* 28. November 1713 in Regensburg; † 1. April 1783 in Augsburg) was an important maker of scientific instruments. Early years Brander was born 1713 to Georg Brandner, an apothecary with roots in Nuremberg, and Sibylla Katharina Brandner (widowed Pfaffreuter, 1678–1756) from a Regensburg goldsmith family. He studied in Altdorf bei Nürnberg from 1731 to 1734 mathematics and physics under the supervision of Johann Gabriel Doppelmayr. Professional work In 1734 he moved to Augsburg (Germany), where he founded a workshop for fine mechanics. He was supported by local financier Josef von Halder with capital and in establishing a business network. Brander was the first one in Germany to build a mirror telescope in 1737. Since 1754 the workshop has produced also microscopes, and the high-resolution micrometer glass rulers were its speciality. A telescope, coupled in 1776 with a map of the starry sky, is named "starfinder". In 1778 he invented the coin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence Microscopy
A fluorescence microscope is an optical microscope that uses fluorescence instead of, or in addition to, scattering, reflection, and attenuation or absorption, to study the properties of organic or inorganic substances. A fluorescence microscope is any microscope that uses fluorescence to generate an image, whether it is a simple setup like an epifluorescence microscope or a more complicated design such as a confocal microscope, which uses optical sectioning to get better resolution of the fluorescence image. Principle The specimen is illuminated with light of a specific wavelength (or wavelengths) which is absorbed by the fluorophores, causing them to emit light of longer wavelengths (i.e., of a different color than the absorbed light). The illumination light is separated from the much weaker emitted fluorescence through the use of a spectral emission filter. Typical components of a fluorescence microscope are a light source (xenon arc lamp or mercury-vapor lamp are com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Society
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, recognising excellence in science, supporting outstanding science, providing scientific advice for policy, education and public engagement and fostering international and global co-operation. Founded on 28 November 1660, it was granted a royal charter by Charles II of England, King Charles II and is the oldest continuously existing scientific academy in the world. The society is governed by its Council, which is chaired by the society's president, according to a set of statutes and standing orders. The members of Council and the president are elected from and by its Fellows, the basic members of the society, who are themselves elected by existing Fellows. , there are about 1,700 fellows, allowed to use the postnominal title FRS (Fellow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Thomas Quekett
John Thomas Quekett (11 August 1815 – 20 August 1861) was an English microscopist and histologist. Quekett studied medicine at the London Hospital in 1831. He became a licentiate of the Apothecaries' Company and a member of the Royal College of Surgeons. In 1839, along with his brother Edwin John Quekett) co-founded the Royal Microscopical Society. Quekett served as the society's secretary from 1841 to 1860. In 1843 he was appointed assistant conservator of the Hunterian Museum, and in 1856 conservator of the museum and professor of histology on the retirement of professor Richard Owen. Biography Quekett, born at Langport, Somerset, on 11 August 1815, was the youngest son of William Quekett and Mary, daughter of John Bartlett. The father was at Cockermouth grammar school with William and Christopher Wordsworth, and from 1790 till his death in 1842 was master of Langport grammar school. He educated his sons at home, and each of them was encouraged to collect specimens in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intestinal Gland
In histology, an intestinal gland (also Crypt (anatomy), crypt of Johann Nathanael Lieberkühn, Lieberkühn and intestinal crypt) is a gland found in between Intestinal villus, villi in the intestinal epithelium, intestinal epithelial lining of the small intestine and large intestine (or colon). The glands and intestinal villi are covered by epithelium, which contains multiple types of Cell (biology), cells: enterocytes (absorbing water and electrolytes), goblet cells (secreting mucus), enteroendocrine cells (secreting hormones), cup cells, myofibroblast, tuft cells, and at the base of the gland, Paneth cells (secreting anti-microbial peptides) and stem cells. Structure Intestinal glands are found in the epithelia of the small intestine, namely the duodenum, jejunum, and ileum, and in the large intestine (colon), where they are sometimes called ''colonic crypts''. Intestinal glands of the small intestine contain a base of replicating stem cells, Paneth cells of the innate immune sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compass (drawing Tool)
A compass, also commonly known as a pair of compasses, is a technical drawing instrument that can be used for inscribing circles or arcs. As dividers, it can also be used as a tool to mark out distances, in particular, on maps. Compasses can be used for mathematics, drafting, navigation and other purposes. Prior to computerization, compasses and other tools for manual drafting were often packaged as a set with interchangeable parts. By the mid-twentieth century, circle templates supplemented the use of compasses. Today those facilities are more often provided by computer-aided design programs, so the physical tools serve mainly a didactic purpose in teaching geometry, technical drawing, etc. Construction and parts Compasses are usually made of metal or plastic, and consist of two "legs" connected by a hinge which can be adjusted to allow changing of the radius of the circle drawn. Typically one leg has a spike at its end for anchoring, and the other leg holds a drawing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athanasius Kircher
Athanasius Kircher (2 May 1602 – 27 November 1680) was a German Society of Jesus, Jesuit scholar and polymath who published around 40 major works of comparative religion, geology, and medicine. Kircher has been compared to fellow Jesuit Roger Joseph Boscovich and to Leonardo da Vinci for his vast range of interests, and has been honoured with the title "Master of a Hundred Arts".Woods, p. 108. He taught for more than 40 years at the Roman College, where he set up a wunderkammer or cabinet of curiosities that would become the Kircherian Museum. A resurgence of interest in Kircher has occurred within the scholarly community in recent decades. Kircher claimed to have deciphered the Egyptian hieroglyphs, hieroglyphic writing of the ancient Egyptian language, but most of his assumptions and translations in the field turned out to be wrong. He did, however, correctly establish the link between the ancient Egyptian and the Coptic language, Coptic languages, and some com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antoni Van Leeuwenhoek
Antonie Philips van Leeuwenhoek ( ; ; 24 October 1632 – 26 August 1723) was a Dutch microbiologist and microscopist in the Golden Age of Dutch art, science and technology. A largely self-taught man in science, he is commonly known as " the Father of Microbiology", and one of the first microscopists and microbiologists. Van Leeuwenhoek is best known for his pioneering work in microscopy and for his contributions toward the establishment of microbiology as a scientific discipline. Raised in Delft, Dutch Republic, Van Leeuwenhoek worked as a draper in his youth and founded his own shop in 1654. He became well-recognized in municipal politics and developed an interest in lensmaking. In the 1670s, he started to explore microbial life with his microscope. Using single-lensed microscopes of his own design and make, Van Leeuwenhoek was the first to observe and to experiment with microbes, which he originally referred to as , or . He was the first to relatively determine their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Julius Richard Petri
Julius Richard Petri (; 31 May 185220 December 1921) was a German microbiologist who is generally credited with inventing the device known as the Petri dish, which is named after him, while working as assistant to bacteriologist Robert Koch. Life and career Petri was born in the town of Barmen (now a district of the city of Wuppertal), Germany, on 31 May 1852. He came from a distinguished family of scholars, and was the eldest son of Philipp Ulrich Martin Petri (18171864), a professor in Berlin, and Louise Petri. Petri's grandfather, Viktor Friedrich Leberecht Petri (1782–1857), was also a scholar, being both a director and professor at the Collegium Carolinum in Brunswick (Braunschweig), Germany. Petri initially studied medicine at the Kaiser Wilhelm Academy for Military Physicians (18711875) and received his medical degree in 1876. He continued his studies at the Charité Hospital in Berlin where his thesis on the chemistry of protein urine tests earned him his doctorate. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
