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Yoked prism can move the image away from primary gaze without the need for a constant head tilt or turn. [1] Prism correction is measured in prism dioptres. A prescription that specifies prism correction will also specify the "base". The base is the thickest part of the lens and is opposite from the apex.
Optical coating. An optical coating is one or more thin layers of material deposited on an optical component such as a lens, prism or mirror, which alters the way in which the optic reflects and transmits light. These coatings have become a key technology in the field of optics. One type of optical coating is an anti-reflective coating, which ...
Corrective lens. A pair of contact lenses, positioned with the concave side facing upward. 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.
Prism (optics) A familiar dispersive prism. An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base ...
A burning apparatus consisting of two biconvex lens. A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis.
Adjustable focus eyeglasses are eyeglasses with an adjustable focal length. They compensate for refractive errors (such as presbyopia) by providing variable focusing, allowing users to adjust them for desired distance or prescription, or both. Current bifocals and progressive lenses are static, in that the user has to change their eye position ...
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. The refractive index of most transparent ...
Bifocals. A bifocal lens with areas of differing magnification. Bifocals with separate lenses. In this case, the Swedish ethnologist Jan-Öjvind Swahn [sv]. Bifocals are eyeglasses with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.