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  2. Abbe number - Wikipedia

    en.wikipedia.org/wiki/Abbe_number

    Abbe number. In optics and lens design, the Abbe number, also known as the V-number or constringence of a transparent material, is an approximate measure of the material's dispersion (change of refractive index versus wavelength), with high values of V indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist ...

  3. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    The Abbe number for a material at a particular refractive index formulation is usually specified as its Abbe value. In practice, an Abbe number change from 30 to 32 will not have a practically noticeable benefit, but a change from 30 to 47 could be beneficial for users with strong prescriptions that move their eyes and look "off-axis" of the ...

  4. Chromatic aberration - Wikipedia

    en.wikipedia.org/wiki/Chromatic_aberration

    Chromatic aberration. Focal length of lens varies with the color of light. 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. [ 1][ 2] It is caused by dispersion: the refractive index of the lens elements ...

  5. Flint glass - Wikipedia

    en.wikipedia.org/wiki/Flint_glass

    Flint glass is optical glass that has relatively high refractive index and low Abbe number (high dispersion ). Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. Traditionally, flint glasses were lead glasses containing ...

  6. Universal Numbering System - Wikipedia

    en.wikipedia.org/wiki/Universal_Numbering_System

    Universal Numbering System. Universal numbering system. This is a dental practitioner view, so tooth number 1, the rear upper tooth on the patient's right, appears on the left of the chart. The Universal Numbering System, sometimes called the "American System", is a dental notation system commonly used in the United States. [ 1][ 2]

  7. Optical aberration - Wikipedia

    en.wikipedia.org/wiki/Optical_aberration

    Optical aberration. 1: Imaging by a lens with chromatic aberration. 2: A lens with less chromatic aberration. In optics, aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. [1]

  8. Achromatic lens - Wikipedia

    en.wikipedia.org/wiki/Achromatic_lens

    In an achromatic lens, two wavelengths are brought into the same focus, here red and blue. An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus on the same plane.

  9. Doctors Say Pooping This Many Times a Day Means You ... - AOL

    www.aol.com/doctors-pooping-many-times-day...

    A new study finds that pooping frequency could predict your overall health. Plus, easy ways to get things moving in the right direction, per the study author.