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Computer vision syndrome. Computer vision syndrome (CVS) is a condition resulting from focusing the eyes on a computer or other display device for protracted, uninterrupted periods of time and the eye's muscles being unable to recover from the constant tension required to maintain focus on a close object.
Light effects on circadian rhythm. Light effects on circadian rhythm are the response of circadian rhythms to light. Most animals and other organisms have a biological clock that synchronizes their physiology and behaviour with the daily changes in the environment. The physiological changes that follow these clocks are known as circadian rhythms.
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 ...
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.
Public fears of cell phone exposure were elevated after an early trial in 2008 found a correlation between glioblastoma (an aggressive malignant brain cancer) and acoustic neuromas, which Saphier ...
A flat lens is a lens whose flat shape allows it to provide distortion-free imaging, potentially with arbitrarily-large apertures. [1] The term is also used to refer to other lenses that provide a negative index of refraction. [2] Flat lenses require a refractive index close to −1 over a broad angular range.
The first contact lenses were made of glass, in 1888. Initially the glass was blown but soon lenses were made by being ground to shape. For the first fifty years, glass was the only material used. The lenses were thin, yet reports of injury were rare. In 1938 perspex (polymethylmethacrylate, or PMMA) began to replace glass in contact lens ...
A photochromic eyeglass lens, part of the lens darkened after exposure to sunlight while the other part remained covered. A photochromic lens is an optical lens that darkens on exposure to light of sufficiently high frequency, most commonly ultraviolet (UV) radiation. In the absence of activating light, the lenses return to their clear state.