Ads
related to: transition lenses problems
Search results
Results From The WOW.Com Content Network
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.
A photochromic eyeglass lens, after exposure to sunlight while part of the lens remained covered by paper. Photochromism is the reversible change of color upon exposure to light. It is a transformation of a chemical species ( photoswitch ) between two forms by the absorption of electromagnetic radiation ( photoisomerization ), where the two ...
Transitions Optical is a U.S.-based company known for manufacturing photochromic lenses, which darken on exposure to specific types of light. The company was founded in 1990. [1] In 1991, Transitions Optical became the first company to commercialize and manufacture plastic photochromic lenses. [2]
where V 1 and V 2 are the Abbe numbers of the materials of the first and second lenses, respectively. Since Abbe numbers are positive, one of the focal lengths must be negative, i.e., a diverging lens, for the condition to be met. The overall focal length of the doublet f is given by the standard formula for thin lenses in contact:
The degree of image blurring for a given amount of focus shift depends inversely on the lens f-number. Low f-numbers, such as f /1.4 to f / 2.8, are very sensitive to defocus and have very shallow depths of focus. High f-numbers, in the f / 16 to f / 32 range, are highly tolerant of defocus, and consequently have large depths of focus.
Photosensitive glass vase. Photosensitive glass, also called photostructurable glass (PSG) or photomachinable glass, is a glass in the lithium-silicate family of glasses onto which images can be etched using shortwave radiations, such as ultraviolet. [1]