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The Michel-Levy Chart (named after Auguste Michel-Lévy) arises when polarised white light is passed through a birefringent sample. If the sample is of uniform thickness, then only one specific wavelength will meet the condition described above, and be perpendicular to the direction of the analyser.
Michel-Lévy interference colour chart issued by Zeiss Microscopy Michel-Lévy pioneered the use of birefringence to identify minerals in thin section with a petrographic microscope . He is widely known for the Michel-Lévy interference colour chart , which defines the interference colors from different orders of birefringence.
The figure can be thought of as a "map" of how the birefringence of a mineral would vary with viewing angle away from perpendicular to the slide, where the central colour is the birefringence seen looking straight down, and the colours further from the centre equivalent to viewing the mineral at ever increasing angles from perpendicular.
Polarizing microscope operating principle Depiction of internal organs of a midge larva via birefringence and polarized light microscopy. Polarized light microscopy can mean any of a number of optical microscopy techniques involving polarized light. Simple techniques include illumination of the sample with polarized light.
The method uses the Michel-Lévy interference colour chart to determine thickness, typically using quartz as the thickness gauge because it is one of the most abundant minerals. When placed between two polarizing filters set at right angles to each other, the optical properties of the minerals in the thin section alter the colour and intensity ...
Birefringence is observed in anisotropic elastic materials. In these materials, the two polarizations split according to their effective refractive indices, which are also sensitive to stress. The study of birefringence in shear waves traveling through the solid Earth (the Earth's liquid core does not support shear waves) is widely used in ...
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.
French geologist Auguste Michel-Lévy devised a chart that correlated the optical properties of minerals to their transmitted color and thickness in the 1880s. Swedish metallurgist J.A. Brinell invented the first quantitative hardness scale in 1900. [ 3 ]