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Rays that leave the object with the same angle cross at the back focal plane. The front and rear (or back) focal planes are defined as the planes, perpendicular to the optic axis, which pass through the front and rear focal points. An object infinitely far from the optical system forms an image at the rear focal plane. For an object at a finite ...
The rear focal length f ′ is the distance from the rear principal plane H ′ to the rear focal point F ′. Front focal distance (FFD) The front focal distance (FFD) (s F) is the distance from the front focal point of the system (F) to the vertex of the first optical surface (S 1). [1] [3] Some authors refer to this as "front focal length".
In optics, a conjugate plane or conjugate focal plane of a given plane P, is the plane P′ such that points on P are imaged on P′. [1] If an object is moved to the point occupied by its image, then the moved object's new image will appear at the point where the object originated.
Planes (geometry) This page was last edited on 5 March 2023, at 19:05 (UTC) . Text is available under the Creative Commons Attribution-ShareAlike 4.0 License ; additional terms may apply.
The f-number N is given by: = where f is the focal length, and D is the diameter of the entrance pupil (effective aperture).It is customary to write f-numbers preceded by "f /", which forms a mathematical expression of the entrance pupil's diameter in terms of f and N. [1]
In mathematics, a parabola is a plane curve which is mirror-symmetrical and is approximately U-shaped. It fits several superficially different mathematical descriptions, which can all be proved to define exactly the same curves. One description of a parabola involves a point (the focus) and a line (the directrix). The focus does not lie on the ...
At the focal plane of a lens, = / (). The intensity at the maximum of the first ring is about 1.75% of the intensity at the center of the Airy disk. The expression for I ( θ ) {\displaystyle I(\theta )} above can be integrated to give the total power contained in the diffraction pattern within a circle of given size:
The distinction between the two meanings is rarely made, since they have almost identical values. The value computed according to the first definition exceeds that from the second by just one focal length. Definition 1 The hyperfocal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably ...