focus, in optics, the point at which rays converge after reflection by a concave mirror mirror, in optics, a reflecting surface that forms an image of an object when light rays coming from that object fall upon it (see reflection ). Usually mirrors are made of plate glass, one side of which is coated with metal or some special preparation to serve as a
..... Click the link for more information. or refraction by a convex lens lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or with one surface plane and the other curved.
..... Click the link for more information. , also known as a real focus. The point from which rays appear to diverge after reflection by a convex mirror or refraction by a concave lens is known as a virtual focus. See image image, in optics, likeness or counterpart of an object produced when rays of light coming from that object are reflected from a mirror or are refracted by a lens .
..... Click the link for more information. .

FOCUS

(1) A DBMS from Information Builders that runs on more than 35 different platforms. FOCUS has been widely known for its 4GL and report writing capabilities and is the product that built the company. It included a hierarchical database in its first release in 1975 and has evolved to support more than 80 database and file types including Information Builders' own multidimensional database (FOCUS Fusion). See EDA, WebFOCUS and FOCUS Fusion.

(2) (Federation On Computing in the United States, www.acm.org/focus) The U.S. representative of the International Federation for Information Processing (IFIP), www.ifip.or.at. FOCUS was founded in 1991 by the ACM and the IEEE Computer Society (IEEE-CS).

(3) (focus) In software, the current window, menu or dialog box that is affected by a key stroke or mouse movement. For example, after you click from one window to another, the second one is said "to have the focus."

focus

1. a point of convergence of light or other electromagnetic radiation, particles, sound waves, etc., or a point from which they appear to diverge

2. another name for focal point focal length

3. Optics the state of an optical image when it is distinct and clearly defined or the state of an instrument producing this image

4. Geometry a fixed reference point on the concave side of a conic section, used when defining its eccentricity

5. the point beneath the earth's surface at which an earthquake or underground nuclear explosion originates

6. Pathol the main site of an infection or a localized region of diseased tissue

focus [′fō·kəs]

(electronics)

To control convergence or divergence of the electron paths within one or more beams, usually by adjusting a voltage or current in a circuit that controls the electric or magnetic fields through which the beams pass, in order to obtain a desired image or a desired current density within the beam.

(geophysics)

The center of an earthquake and the origin of its elastic waves within the earth.

(mathematics)

A point in the plane which together with a line (directrix) defines a conic section.

(nucleonics)

To guide particles along a desired path in a particle accelerator by means of electric or magnetic fields.

(optics)

The point or small region at which rays converge or from which they appear to diverge.

To move an optical lens toward or away from a screen or film to obtain the sharpest possible image of a desired object.

(database, language)

FOCUS - A hierarchical database language from Information Builders, Inc.

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FOCUS

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