Focal length

The distance between the focal point and the vertex of a mirror or lens. For concave mirrors and convex lenses, this number is positive. For convex mirrors and concave lenses, ...

focal length

Engineering; Electronic engineering

Symbol, F. The distance from the center of a lens or dish antenna to the principal focus.

focal length

Earth science; Remote sensing

In cameras, the distance from the optical center of the lens to the plane at which the image of a very distant object is brought into focus.

focal length

Consumer electronics; Digital camera

The distance from the rear model plane of a lens to the focus when the lens is focused at the infinity position.

ophthalmoscope

Eyewear; Optometry

An optical instrument used to examine the external and internal parts of the eye, particularly the media and the fundus.

pantoscopic angle

Eyewear; Optometry

1. Angle in the vertical plane between the optical axis of a spectacle lens and the visual axis of the eye in the primary position, usually taken to be the horizontal. 2. Angle ...

optical material

Eyewear; Optometry

Transparent material capable of being manufactured into optical components.

optical radiation hazard

Eyewear; Optometry

Possibility of damage to the retina by optical radiation.

optical centre

Eyewear; Optometry

For practical purposes, the intersection of the optical axis with the front surface a lens.

ophthalmoscope

Optometry; Optometry

An optical instrument used to examine the external and internal parts of the eye, particularly the media and the fundus.

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Industry/Domain: Festivals Category: Easter

Easter

An annual Christian festival in commemoration of the resurrection of Jesus Christ, observed on the first Sunday after the first full moon after the ...