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The aim of an accurate intraocular lens power calculation is to provide an intraocular lens (IOL) that fits the specific needs and desires of the individual patient. The development of better instrumentation for measuring the eye's axial length (AL) and the use of more precise mathematical formulas to perform the appropriate calculations have significantly improved the accuracy with which the ...
A CCTV camera housing made by Pelco. Pelco Incorporated is an American security and surveillance technologies company. Founded in 1957 and headquartered in Fresno, California, [4] Pelco is a wholly owned subsidiary of Motorola Solutions. The company's products include security cameras, recording and management systems, and video analytics software.
The numerical aperture with respect to a point P depends on the half-angle, θ1, of the maximum cone of light that can enter or exit the lens and the ambient index of refraction. As a pencil of light goes through a flat plane of glass, its half-angle changes to θ2. Due to Snell's law, the numerical aperture remains the same: NA = n1 sin θ1 ...
Focal length. The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a ...
In optics and photography, hyperfocal distance is a distance from a lens beyond which all objects can be brought into an "acceptable" focus. As the hyperfocal distance is the focus distance giving the maximum depth of field, it is the most desirable distance to set the focus of a fixed-focus camera. [1] The hyperfocal distance is entirely ...
35 mm equivalent focal length. The resulting images from 50 mm and 70 mm lenses for different sensor sizes; 36x24 mm (red) and 24x18 mm (blue) In photography, the 35 mm equivalent focal length is a measure of the angle of view for a particular combination of a camera lens and film or image sensor size. The term is popular because in the early ...
The lens is to the left. Correction. In lens systems, aberrations can be minimized using combinations of convex and concave lenses, or by using aspheric lenses or aplanatic lenses. Lens systems with aberration correction are usually designed by numerical ray tracing. For simple designs, one can sometimes analytically calculate parameters that ...
Lens clock. A lens clock is a mechanical dial indicator that is used to measure the dioptric power of a lens.It is a specialized version of a spherometer.A lens clock measures the curvature of a surface, but gives the result as an optical power in diopters, assuming the lens is made of a material with a particular refractive index.