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Yrjö Väisälä
Yrjö Väisälä (; 6 September 1891 – 21 July 1971) was a Finnish astronomer and physicist. His main contributions were in the field of optics. He was also active in geodetics, astronomy and optical metrology. He had an affectionate nickname of ''Wizard of Tuorla'' (Observatory/Optics laboratory), and a book with the same title in Finnish describes his works. His discoveries include 128 minor planets and 3 comets. His brothers were mathematician Kalle Väisälä (1893–1968) and meteorologist Vilho Väisälä (1889–1969). His daughter Marja Väisälä (1916–2011) was an astronomer and discoverer of minor planets. Väisälä was a fervent supporter of Esperanto, presiding over the ''Internacia Scienca Asocio Esperantista'' ("International Association of Esperanto Scientists") in 1968. Optician He developed several methods for measuring the quality of optical elements, as well as a lot of practical methods of manufacturing said elements. This allowed the constru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joensuu
Joensuu (; krl, Jovensuu; ) is a city and municipality in North Karelia, Finland, located on the northern shore of Lake Pyhäselkä (northern part of Lake Saimaa) at the mouth of the Pielinen River (''Pielisjoki''). It was founded in 1848. The population of Joensuu is (), and the economic region of Joensuu has a population of 115,000. It is the largest city in Finland. The nearest major city, Kuopio in North Savonia, is located to the west. From Joensuu, the distance to Lappeenranta, the capital of South Karelia, is along Highway 6. As is typical of cities in Eastern Finland, Joensuu is monolingually Finnish. Along with Kuopio, Joensuu is one of major urban, economic, and cultural hubs of Eastern Finland. Joensuu is a student city with a subsidiary of the University of Eastern Finland, which has over 20,000 enrolled students, and a further 4,000 students at the Karelia University of Applied Sciences. Heraldry The explanation of the coat of arms of Joensuu reads: ”shie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vilho Väisälä
Vilho Väisälä (; September 28, 1889 – August 12, 1969) was a Finnish meteorologist and physicist, and founder of Vaisala Oyj. After graduation in mathematics in 1912, Väisälä worked for the Finnish Meteorological Institute in ''aerological measurements'', specializing in the research of the higher troposphere. At the time the measurements were conducted by attaching a thermograph to a kite. In 1917 he published his dissertation in mathematics ''Ensimmäisen lajin elliptisen integralin käänteisfunktion yksikäsitteisyys'' (The single-valuedness of the inverse function of the elliptic integral of the first kind). His dissertation was the first and still is the only mathematical doctoral thesis written in the Finnish language.Lehto, Olli: Oman tien kulkijat. Helsinki: Otava, 2004. . Page 101 Väisälä participated in development of radiosonde, a device attached to a balloon and launched to measure air in the higher atmosphere. In 1936 he started his own company, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nummela (Vihti)
Nummela () is the largest urban agglomeration and municipality seat of Vihti municipality in Southern Finland. Nummela is located in a triangle between highways 1, 2 and 25, northwest from the capital Helsinki, northeast from the city of Lohja and southwest from Ojakkala, the third largest settlement in Vihti. Population of Nummela's urban area is around 13 500 and population within its post code is around 15 000. Nummela has an airport (ICAO: EFNU) that is suitable for gliding. Famous people from Nummela *, writer * |
Finnish Geodetic Institute
The Finnish Geospatial Research Institute ( fi, Paikkatietokeskus), formerly Finnish Geodetic Institute (FGI, fi, Geodeettinen laitos, sv, Geodetiska institutet) is a research institute in Finland specializing in geodesy and geospatial information science and technology. It merged into the National Land Survey of Finland in 2015, when its name was changed. It is located in Masala, Kirkkonummi. History The FGI was founded in 1918. The institute creates and maintains national coordinate, height, and gravity systems. It also participates in projects that try to advance spatial data infrastructure and conducts research on geodynamics, advanced spatial data and remote sensing and photogrammetry Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima .... The institute also has a statutory respo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nummela Standard Baseline
Nummela Standard Baseline is a baseline used to calibrate rangefinders, in Finland, located in the municipality of Vihti, Nummelanharju (esker) where it was built in 1932. Winding ridge of stratified gravel and sand was chosen as a location for measurements since temperature variations cause very little displacement on soil where benchmarks are located. Measurement devices such as theodolite and mirrors are then placed on those pillars. Careful preliminary measurements such as levelling height differences of observation pillars reference points are required before actual measurements can begin. In 1947, a white light interference based measurement system was taken to use. It was developed by Yrjö Väisälä. Before that baseline was defined by quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an ove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Light Interferometry
As described here, white light interferometry is a non-contact optical method for surface height measurement on 3D structures with surface profiles varying between tens of nanometers and a few centimeters. It is often used as an alternative name for coherence scanning interferometry in the context of areal surface topography instrumentation that relies on spectrally-broadband, visible-wavelength light (white light). Basic principles Interferometry makes use of the wave superposition principle to combine waves in a way that will cause the result of their combination to extract information from those instantaneous wave fronts. This works because when two waves combine, the resulting pattern is determined by the phase difference between the two waves—waves that are in phase will undergo constructive interference while waves that are out of phase will undergo destructive interference. While white light interferometry is not new, combining old interferometry techniques with modern ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaisala Diary
Vaisala Oyj () is a Finnish company that develops, manufactures and markets products and services for environmental and industrial measurement. Their major customer groups and markets are national meteorological and hydrological services, aviation authorities, defense forces, road authorities, the weather critical energy sector, life science and high-technology industries and building automation. Vaisala had over 1,900 employees and net sales of €379.5 million in 2020. Vaisala serves customers in more than 150 countries. The parent company Vaisala Oyj, domicile in Vantaa, Finland, is listed on the NASDAQ OMX Helsinki. Vaisala Group has offices and operations in Finland, the United States, Australia, Brazil, Canada, China, France, Germany, India, Italy, Japan, Kenya, Malaysia, México, South Korea, Sweden, United Arab Emirates, and the United Kingdom. History Vaisala originated in the 1930s when Professor Vilho Väisälä (1889–1969), Vaisala's founder and long-time managi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Mirror Telescope
The MMT Observatory (MMTO) is an astronomical observatory on the site of Fred Lawrence Whipple Observatory (IAU observatory code 696). The Whipple observatory complex is located on Mount Hopkins, Arizona, US (55 km south of Tucson) in the Santa Rita Mountains. The observatory is operated by the University of Arizona and the Smithsonian Institution, and has a visitor center in nearby Amado, Arizona. The MMTO is the home of the MMT (formerly Multiple Mirror Telescope), which has a primary mirror 6.5 m in diameter. The name comes from the six smaller mirrors originally used before the single primary mirror was installed in 1998. The primary mirror has a special lightweight honeycomb design made by the University of Arizona's Steward Observatory Mirror Laboratory. The MMT is housed in a building which allows the walls and roof around the telescope to be completely rolled back, allowing it to cool down very quickly in order to improve observation. Multiple Mirror Telescope (197 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Plate
Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thinner than common window glass. History Glass plates were far superior to film for research-quality imaging because they were stable and less likely to bend or distort, especially in large-format frames for wide-field imaging. Early plates used the wet collodion process. The wet plate process was replaced late in the 19th century by gelatin dry plates. A view camera nicknamed "The Mammoth" weighing was built by George R. Lawrence in 1899, specifically to photograph "The Alton Limited" train owned by the Chicago & Alton Railway. It took photographs on glass plates measuring × . Glass plate photographic material largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile fil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernhard Schmidt
Bernhard Woldemar Schmidt (, Naissaar, Nargen – 1 December 1935, Hamburg) was an Estonian optician. In 1930 he invented the Schmidt camera, Schmidt telescope which corrected for the optical errors of spherical aberration, coma, and astigmatism, making possible for the first time the construction of very large, wide-angled reflective cameras of short exposure time for astronomical research. Childhood Schmidt was the son of Carl Constantin and Marie Helene Christine ( Rosen) Schmidt. He was born and grew up on the island of Naissaar, Nargen (Naissaar), off the coast of Reval (Tallinn), Governorate of Estonia, Estonia, then part of the Russian Empire. The inhabitants of this island, mainly Estonian Swedes, generally spoke Swedish language, Swedish or Estonian language, Estonian, but the Schmidt family also spoke German language, German. Bernhard was the oldest of six children, three boys (one of whom died in infancy) and three girls. Naissaar was a small, rural island whose popu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schmidt Camera
A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric astrophotographic telescope designed to provide wide fields of view with limited aberrations. The design was invented by Bernhard Schmidt in 1930. Some notable examples are the Samuel Oschin telescope (formerly Palomar Schmidt), the UK Schmidt Telescope and the ESO Schmidt; these provided the major source of all-sky photographic imaging from 1950 until 2000, when electronic detectors took over. A recent example is the Kepler space telescope exoplanet finder. Other related designs are the Wright camera and Lurie–Houghton telescope. Invention and design The Schmidt camera was invented by German–Estonian optician Bernhard Schmidt in 1930. Its optical components are an easy-to-make spherical primary mirror, and an aspherical correcting lens, known as a Schmidt corrector plate, located at the center of curvature of the primary mirror. The film or other detector is placed inside the camera, at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
