GNU Collaborative International Dictionary of English

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Found 2 definitions

1.       
   Achromatic , a. [Gr. ἀχρώματος colorless; ἀ priv. + χρῶμα, χρώματος, color: cf. F. achromatique.]
   (Opt.) Free from color; transmitting light without decomposing it into its primary colors.
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   (Biol.) Uncolored; not absorbing color from a fluid; -- said of tissue.
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   Achromatic lens (Opt.), a lens composed usually of two separate lenses, a convex and concave, of substances having different refractive and dispersive powers, as crown and flint glass, with the curvatures so adjusted that the chromatic aberration produced by the one is corrected by other, and light emerges from the compound lens undecomposed. -- Achromatic prism. See Prism. -- Achromatic telescope, or microscope, one in which the chromatic aberration is corrected, usually by means of a compound or achromatic object glass, and which gives images free from extraneous color.
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2.       
   Microscope , n. [Micro- + -scope.] An optical instrument, consisting of a lens, or combination of lenses, for making an enlarged image of an object which is too minute to be viewed by the naked eye.
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   Compound microscope, an instrument consisting of a combination of lenses such that the image formed by the lens or set of lenses nearest the object (called the objective) is magnified by another lens called the ocular or eyepiece. -- Oxyhydrogen microscope, and Solar microscope. See under Oxyhydrogen, and Solar. -- Simple microscope, or Single microscope, a single convex lens used to magnify objects placed in its focus.
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