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The stone's pattern resembles the chrysanthemum flower. The flower is milky white and grain is clear. Chrysanthemum stone is generally dark-gray or black, and does not contain radioactive elements, so it has a high collection value. Although the composition of chrysanthemum stone itself is not very rare, the formation is uncommon, so the stone ...
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A petrographic microscope, which is an optical microscope fitted with cross-polarizing lenses, a conoscopic lens, and compensators (plates of anisotropic materials; gypsum plates and quartz wedges are common), for crystallographic analysis. Optical mineralogy is the study of minerals and rocks by measuring their optical properties.
Although its extent in Germany is limited to the extreme south of Bavaria, this narrow strip has relatively high geological diversity. In this region, three of the four major tectonic "domains" of the Alps are found: the Helvetic nappes , the Penninic nappes (as the Rhenodanubian Flysch Zone) and the Eastern Alps (as the Northern Limestone Alps ).
A 1951 USAF resolution test chart is a microscopic optical resolution test device originally defined by the U.S. Air Force MIL-STD-150A standard of 1951. The design provides numerous small target shapes exhibiting a stepped assortment of precise spatial frequency specimens.
These older northern patterns have been eclipsed by the double-headed New Altenburg, New German or East German pattern, created by Walter Krauss (1908–1985) in the former East Germany, which added corner indices to every card but the Aces and cleverly changed the dimensions of the cards to match those of standard poker or rummy cards.
The zone plate's focusing ability is an extension of the Arago spot phenomenon caused by diffraction from an opaque disc. [2] A zone plate consists of a set of concentric rings, known as Fresnel zones, which alternate between being opaque and transparent. Light hitting the zone plate will diffract around the opaque zones.
The test consists of a number of Ishihara plates, which are a type of pseudoisochromatic plate. Each plate depicts a solid circle of colored dots appearing randomized in color and size. [ 3 ] Within the pattern are dots which form a number or shape clearly visible to those with normal color vision, and invisible, or difficult to see, to those ...