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Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
The strength of the prism is increased until the streak of the light passes through the centre of the prism, as the strength of the prism indicates the amount of deviation present. The Maddox rod is a handheld instrument composed of red parallel plano convex cylinder lens , which refracts light rays so that a point source of light is seen as a ...
Esotropia is a form of strabismus in which one or both eyes turn inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance. [1] It is the opposite of exotropia and usually involves more severe axis deviation than esophoria. Esotropia is sometimes erroneously called ...
Gravity is computed on the ellipsoid surface using the International Gravity Formula. For studies of subsurface structure, the free-air anomaly is further adjusted by a correction for the mass below the measurement point and above the reference of mean sea level or a local datum elevation. This defines the Bouguer anomaly. Calculation
Prism (optics) 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 and rectangular sides.
The Taylor knock-out factor, also called Taylor KO factor or TKOF, is a formulaic mathematical approach for evaluating the stopping power of hunting cartridges, developed by John "Pondoro" Taylor in the middle of the 20th century. Taylor, an elephant hunter and author who wrote two books about rifles and cartridges for African hunting, devised ...
The Prentice position is an orientation of a prism, used in optics, optometry and ophthalmology. In this position, named after the optician Charles F. Prentice, the prism is oriented such that light enters it at an angle of 90° to the first surface, so that the beam does not refract at that surface. All the deviation caused by the prism takes ...
A brass, spherical Helmholtz resonator based on his original design, circa 1890–1900. Helmholtz resonance, also known as wind throb, refers to the phenomenon of air resonance in a cavity, an effect named after the German physicist Hermann von Helmholtz. [1] This type of resonance occurs when air is forced in and out of a cavity, causing the ...
Condensed matter physics. Surface plasmon polaritons ( SPPs) are electromagnetic waves that travel along a metal – dielectric or metal–air interface, practically in the infrared or visible -frequency. The term "surface plasmon polariton" explains that the wave involves both charge motion in the metal ("surface plasmon") and electromagnetic ...
Sight is defined as the observation of the altitude, and sometimes also the azimuth, of a celestial body for a line of position; or the data obtained by such observation. [1] The mathematical basis of sight reduction is the circle of equal altitude. The calculation can be done by computer, or by hand via tabular methods and longhand methods.