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t. e. PRISM is a code name for a program under which the United States National Security Agency (NSA) collects internet communications from various U.S. internet companies. [1] [2] [3] The program is also known by the SIGAD US-984XN. [4] [5] PRISM collects stored internet communications based on demands made to internet companies such as Google ...
The Peli Lens is a mobility aid for people with homonymous hemianopia. It is also known as “EP” or Expansion Prism concept and was developed by Dr. Eli Peli of Schepens Eye Research Institute in 1999. It expands the visual field by 20 degrees. He tested this concept on several patients in his private practice with great success using 40Δ ...
In some lenses, the curved surfaces are replaced with flat surfaces, with a different angle in each section. Such a lens can be regarded as an array of prisms arranged in a circular fashion with steeper prisms on the edges and a flat or slightly convex center. In the first (and largest) Fresnel lenses, each section was actually a separate prism.
An example is eyeglass lenses that are used to correct astigmatism in someone's eye. Types of simple lenses Types of lenses. Lenses are classified by the curvature of the two optical surfaces. A lens is biconvex (or double convex, or just convex) if both surfaces are convex. If both surfaces have the same radius of curvature, the lens is ...
However they have large eye lenses, excellent eye relief, and are comfortable to use at lower powers. Field flattener lens. High-end binoculars often incorporate a field flattener lens in the eyepiece behind their prism configuration, designed to improve image sharpness and reduce image distortion at the outer regions of the field of view.
An aspheric lens or asphere (often labeled ASPH on eye pieces) is a lens whose surface profiles are not portions of a sphere or cylinder. In photography, a lens assembly that includes an aspheric element is often called an aspherical lens . The asphere's more complex surface profile can reduce or eliminate spherical aberration and also reduce ...
A reflex finder is a viewfinder system with a mirror placed behind a lens. The light passing through the lens is reflected by the mirror to a focusing screen, usually ground glass. The image formed on this ground glass can be observed directly, giving a waist-level reflex finder, or through a redressing optical device (set of mirrors or prism ...
The original video by Pinkfong is now the most viewed video on the site. On October 29, 2020, Baby Shark surpassed 7 billion views, and on November 2, 2020, it passed Despacito to become the most viewed video on YouTube. On February 23, 2021, Baby Shark surpassed 8 billion views, becoming the first video to do so.