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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] |
