Focal point

Focal Point
The focal length ( f ) is the distance from a lens or mirror to the focal point ( F ). Light rays (of a single frequency) travelling parallel to the optical axis of a lens or mirror will meet at the focal point.

Focal Point - The spot where parallel beams of light striking a lens or mirror are brought to a focus ...

focal point
The point in an optical path where beams of light converge to a point, creating a focused image of an object.
focus ...

Focal point
The focal point of a lens or mirror is the point in space where parallel light rays meet after passing through the lens or bouncing off the mirror.

The focal point of the large primary reflecting mirror in astronomical telescopes when the light source is extremely distant.

One of two focal points available for telescopes mounted on alt-azimuth mountings which are fixed as the telescope moves in altitude. The light is reflected down the hollow altitude axis to emerge at the side of the telescope.
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Putting the focal point in your eye is not useful, but we are not done with our lesson on how converging lenses work. It may surprise you to know that in order to understand telescopes, you must first understand how a simple magnifying glass works.

serves as a focal point for women's health research at the NIH. The ORWH promotes, stimulates, and supports efforts to improve the health of women through biomedical and behavioral research.

solar thermal propulsion (NASA Thesaurus) Proposed energy source for spacecraft propulsion by passing hydrogen through a heat exchanger placed at the focal point of a large parabolic dish solar concentrator mirror.

focal point = focus, in optics. focus (plural focuses) 1. That point at which parallel rays of light meet after being refracted by a lens or reflected by a mirror. Also called focal point. 2.

This form is due to the method used to aim the telescope: the telescope's dish is fixed in place, but the receiver at its focal point is repositioned to intercept signals reflected from different directions by the spherical dish surface.

By the end of the century, the focal point of culture had moved to the United States, especially New York City and Los Angeles.
Movies, music and the media had a major influence on fashion and trends in all aspects of life.

The orbit of a planet around the Sun is an ellipse, with the Sun in one of the focal points of the ellipse. Therefore the orbit lies in a plane, called the orbital plane. The point on the orbit closest to the attracting body is the periapsis.

Focal point. The focal point of a lens is defined by considering a parallel bundle or beam of light incident upon the lens, parallel to the optic (symmetry) axis of the lens.

The dish is 64 meters in diameter with a focal point 27 meters above the dish center. Featured in the movie "The Dish", the Parkes Radio Telescope is the one that received the best TV signals from the Apollo 11 mission in 1969.

means of measuring the focal point were provided; symmetrical motion was given to the slides; scales on each slide were provided instead of screws for measuring the separation of the segments, ...

This is because large lenses are very difficult to construct and lenses suffer from ``chromatic aberration'' which is the tendency to bring light of various colors to different focal points.

This point is called the Focal Point. The longer the focal length of the telescope, generally the more power it has, the larger the image and the smaller the field of view.

Spherical aberration - A common form of optical aberration caused when the light from the periphery of a mirror or lens doesn't have the same focal point as light from the center.

A device used on a radio telescope. It is located at the focal point and acts as a receiver of radio waves which the antenna collects and focuses on it. It couples the energy into the lines to go into the amplifier. [H76]
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This translates the focal point to a position near the apex of the primary where it is more accessible, and where practical antenna feeds are less responsive to radiations arriving from very wide angles relative to the nominal pointing direction.

The Sun is not at the center of the ellipse, but at one of its two geometric focal points, each currently about 2.5 million km from the center. Hence, the Earth-Sun distance varies some 5 million km throughout the year.

CHROMATIC ABERATION - Effect that occurs in a lens when radiation of different wavelengths is brought to focus at different focal points. In light microscopy this implies that, for instance, red and blue rays have different foci.

The distance from the center of the field lens (where light passes through the first element of the eyepiece) to the focal point. The magnification of a telescope varies with the eyepiece focal length.

Lower frequency (10 MHz - 100 MHz (wavelengths of 30 meters to 3 meters)) instruments are generally arrays of antennas similar to "TV antennas" or are stationary reflectors of gigantic proportions with moveable focal points some are over 30 meters ...

focal length
The length of the path of light from the main mirror or lens to the focal point (the eyepiece).

A type of telescope, also known as a reflecting telescope, that uses one or more polished, curved mirrors to gather light and reflect it to a focal point.
Refractor ...

Mirrors in X-ray telescopes are arrangements of flat surfaces or concentric tubes arranged so that the incoming X-rays strike at glancing (grazing) incidence and deflect toward a focal point in one or more stages.

See also: Light, Second, Field, Focus, Time