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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 ...
Corrective lens. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
An optical instrument is said to be diffraction-limited if it has reached this limit of resolution performance. Other factors may affect an optical system's performance, such as lens imperfections or aberrations, but these are caused by errors in the manufacture or calculation of a lens, whereas the diffraction limit is the maximum resolution ...
Abbe condensers are difficult to use for magnifications of above 400X, as the aplanatic cone is only representative of a numerical aperture (NA) of 0.6. This condenser is composed of two lenses, a plano-convex lens somewhat larger than a hemisphere and a large bi-convex lens serving as a collecting lens to the first.
The multifocal lenses can correct defective vision in multiple focus, for example: near-vision as well as far-vision. This are particularly beneficial for presbyobia. Contact lenses. Alternatively, many people choose to wear contact lenses. One style is hard contact lenses, which can distort the shape of the cornea to a desired shape.
The reduced eye is an idealized model of the optics of the human eye. Introduced by Franciscus Donders, the reduced eye model replaces the several refracting bodies of the eye (the cornea, lens, aqueous humor, and vitreous humor) by an ideal air/water interface surface that is located 20 mm from a model retina. This, converts a system with six ...
Unfortunately, a nursing education comes with a hefty price tag. The cost can range from $4,000 for an associate degree in nursing to above $150,000 for an advanced degree. Other factors adding to ...
The model was developed by Dr. Kathleen Stevens at the Academic Center for Evidence-Based Practice located at the University of Texas Health Science Center at San Antonio. The model has been represented in many nursing textbooks , used as part of an intervention to increase EBP competencies, and as a framework for instruments measuring EBP ...