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In optics, an index-matching material is a substance, usually a liquid, cement (adhesive), or gel, which has an index of refraction that closely approximates that of another object (such as a lens, material, fiber-optic, etc.). When two substances with the same index are next to each other, light passes from one to the other with neither reflection nor refraction. As such, they are used for various purposes in science, engineering, and art. For example, in a popular home experiment, a glass rod is made almost invisible by immersing it in an index-matched transparent fluid such as mineral spirits.〔(Optics For Kids - "Lose a glass in a glass" home experiment )〕 ==In microscopy== (詳細はlight microscopy, oil immersion is a technique used to increase the resolution of a microscope. This is achieved by immersing both the objective lens and the specimen in a transparent oil of high refractive index, thereby increasing the numerical aperture of the objective lens. Immersion oils are transparent oils that have specific optical and viscosity characteristics necessary for use in microscopy. Typical oils used have an index of refraction around 1.515.〔("Microscope Objectives: Immersion Media" ) by Mortimer Abramowitz and Michael W. Davidson, ''Olympus Microscopy Resource Center'' (website), 2002.〕 An oil immersion objective is an objective lens specially designed to be used in this way. The index of the oil is typically chosen to match the index of the microscope lens glass, and of the cover slip. For more details, see the main article, oil immersion. Some microscopes also use other index-matching materials besides oil; see water immersion objective and solid immersion lens. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Index-matching material」の詳細全文を読む スポンサード リンク
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