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Lenses made of PMMA are called hard lenses. [5] Soft contact lenses were first produced in 1961 by Czech chemical engineer Otto Wichterle using polyhydroxyethylmethacrylate (pHEMA), a material that achieved long-term commercial application. Lenses made of polyacrylamide were introduced in 1971. [5]
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 ...
Acuvue lenses got their start at Frontier Contact Lens Company, founded in Buffalo, New York in 1959 by Dr. Allen Isen, George Sitterle, and Dr. William Feinbloom. [1] Its early growth was attributed to its highly successful toric lens. In 1962, Seymour Marco joined the venture and Frontier moved its operations to Jacksonville, Florida. [2]
Chromatic aberration. 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 varies with the wavelength of light.
Ice lens. Pingo formed in arctic tundra as a result of periodically spaced ice lens formation. Ice lenses are bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing crack, and, as long as the conditions remain favorable ...
Low-dispersion glass ( LD glass) is a type of glass with a reduction in chromatic aberration (less rainbow effect). Crown glass is an example of a relatively inexpensive low-dispersion glass. Special low dispersion glass (SLD glass) and extraordinary low-dispersion glass (ELD glass) are glasses with yet lower dispersion (and yet higher price).
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