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The cardinal points of a thick lens in air. F, F ′ front and rear focal points; P, P ′ front and rear principal points; V, V ′ front and rear surface vertices.. The cardinal points lie on the optical axis of an optical system.
Gaussian optics is named after mathematician and physicist Carl Friedrich Gauss, who showed that an optical system can be characterized by a series of cardinal points, which allow one to calculate its optical properties. [2]
A single lens can form images of objects at a variety of distances; the position of the image plane depends on where the object is relative to the lens. The cardinal points, on the other hand, are properties of the optical system. Unless the geometry of the lens changes (as in a zoom lens), the cardinal points remain fixed.
The reduced eye is an idealized model of the optics of the human eye. Introduced by Franciscus Donders, the reduced eye model replaces the several refracting bodies of the eye (the cornea, lens, aqueous humor, and vitreous humor) are replaced by an ideal air/water interface surface that is located 20 mm from a model retina.
As the front element of the Tessar has three times the power of the whole lens, it must be moved one-third of the distance that the whole lens would need to move to focus at the same point. The large airspace between the first and second elements allows focusing by moving the front element only; as the displacement is small compared with the ...
Camera; Camera lens; Camera lucida; Camera obscura; Candela; Cardinal point (optics) Cassegrain reflector; Cathodoluminescence; Catoptrics; Caustic (optics) Chatoyancy
r = position from aperture diffracted from it to a point; α 0 = incident angle with respect to the normal, from source to aperture; α = diffracted angle, from aperture to a point; S = imaginary surface bounded by aperture ^ = unit normal vector to the aperture
For a lens, or a spherical or parabolic mirror, it is a point onto which collimated light parallel to the axis is focused. Since light can pass through a lens in either direction, a lens has two focal points – one on each side. The distance in air from the lens or mirror's principal plane to the focus is called the focal length.