Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
1999-02-02
2001-12-04
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C345S427000, C345S440000, C348S218100, C359S664000
Reexamination Certificate
active
06327097
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an optical imaging system for reproducing an object with an infinitely variable magnification (zoom), as well as to a graphic user interface.
From SCHRÖDER, G.: Technische Optik, 7
th
edition, Vogel Buchverlag Würzburg, pages 128 ff., an optical imaging system in the form of a zoom lens is known, which enables an object to be reproduced with an infinitely variable magnification.
The previously known zoom lens consists essentially of several lenses, two of the lenses being movable along the optical axis. This makes it possible, on the one hand, to vary the focal length and, with that, the magnification infinitely and, on the other, to adapt the focusing to the changed focal length, so that the plane of the image plane can remain unchanged when the focal length is varied.
It is a problem of the previously known zoom lens that the sine error, which arises during the reproduction, varies with the respective focal length setting of the zoom lens. When images with different focal length settings are superimposed, this variation leads to an image, which gives the impression of being unnatural, because of the different optical imaging errors of the images, which are to be superimposed.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an optical imaging system, which enables an object to be reproduced with infinitely variable magnification and with sine errors, which are independent of the respective magnification. It is furthermore an object of the invention to provide a graphic user interface for the multivalent representation of the image.
The invention includes the technical teachings of reproducing the object initially independently of the respective focal length setting with a constant magnification on a two-dimensional interim image and of then photographing this interim image with the desired magnification, so that the sine distortions, occurring during the reproduction process, are independent of the respective focal length setting.
The concept of object is to be understood generally here and in the following and comprises an individual object, a spatial scene as well as a two-dimensional presentation.
Pursuant to the invention, preferably those light rays, which emanate from the object and pass through the nodal or focal point, form the image. For selecting the light rays, passing through the nodal point, from the totality of the rays emanating from the object, an optical element is provided pursuant to the invention and, in a preferred embodiment, is formed as a spherical lens. The light rays, which strike the spherical lens perpendicularly to the spherical surface, experience, in accordance with the refractive index law, no or only a slight change in direction, and thus proceed centrally through the center point of the spherical lens, whereas the remaining rays are deflected and thus do not contribute to the imaging. The spherical lens thus selects the rays, which strike the lens from a wide-angled region and, at the same time, pass centrally through its center point, so that the center point of the spherical lens is the nodal or focal point of the imaging rays.
The invention, however, is not limited to a spherical lens for selecting the rays passing through the nodal point. For example, a pinhole diaphragm or an appropriate lens system can also be used. The nodal or focal point of the imaging rays coincides here with the center point of the pinhole diaphragm.
When a spherical lens is used, as well as when a pinhole diaphragm is used for selecting the rays passing through a certain nodal point, it is, in principle, not possible and, for an adequate intensity of light, also not desirable to select exclusively those rays, which pass exactly through the nodal point. Rather, other rays also, which extend in the vicinity of the nodal point, are interrupted, forming the image, and, with that, selected. The only thing that matters for the functioning of the inventive optical imaging system is that the optical element produces a constricted bundle of rays in the region of the nodal point.
Furthermore, the inventive, optical imaging system preferably has a further optical element, which is downstream from the first optical element and preferably has at least one planoconcave lens or a lens system, containing a corresponding optical system, the concavely shaped side of the planoconcave lens facing the first optical element. For a preferred embodiment, the planoconcave lens is disposed in such a manner, that its focal point coincides with the nodal point of the imaging rays, so that, the rays, passing through the nodal point, after being deflected by the planoconcave lens, proceed parallel to the optical axis. Thus, from a diverging bundle of rays, the planoconcave lens generates parallel rays, which extend at right angles to the plane surface of the planoconcave lens.
In a preferred embodiment of the invention, the radius of the spherical lens is equal to the radius of curvature of the planoconcave lens, so that, on the side averted from the object, the spherical lens fits into the concave curvature of the planoconcave lens or of a corresponding optical system and forms a unit with the latter. For this embodiment, it is important that the refractive index of the planoconcave lens or of the corresponding optical system differs from the refractive index of the spherical lens, since otherwise the light rays would not be refracted at the interface between the spherical lens and the planoconcave lens.
Pursuant to the invention, the planoconcave lens (or the corresponding optical element, guiding the rays, emanating from the object, to a plane pictorial representation) is provided on its plane side with an interim image plane, preferably in the form of a diffusor layer, which enables an interim image to be generated from the parallel rays. This interim image plane, preferably in the form of a diffusor layer, can be either mounted directly on the plane surface of the planoconcave lens or consist of a separate diffusor plate.
The inventive optical imaging system thus initially selects, from the totality of light rays emanating from the object, essentially the rays, which pass through a particular nodal point. These light rays are then directed parallel to one another by the planoconcave lens or by an appropriate optical system and, on the interim image plane, which preferably is in the form of a diffusor layer, generate an interim image, which reproduces a wide-angled section of the image in orthographic projection.
By means of imaging optics with a fixed focal length, this interim image is then reproduced on a photosensitive imaging surface, which is directed parallel to the interim image plane, preferably in the form of a diffusor layer, and consists of a light-sensitive film or a CCD sensor element as target. The diaphragm plane is between the interim image plane and the imaging plane, that is, as seen from the object, on the far side of the focus of the first optical element.
For adjusting the focal length and/or for focusing the image, appearing on the imaging plane, the imaging optics and/or the imaging plane are disposed so that they can be shifted parallel to the optical axis. By shifting the imaging optics and/or the imaging plane parallel to the optical axis, the magnification and, with that, the section of the image appearing on the imaging plane, can be adjusted infinitely variably. The arrangement functions like a zoom lens, the distortion being independent of the “focal length setting” and, with that, does not have to be corrected. The focal point of the first optical element is in front of the diaphragm plane.
In the simplest version, the imaging optics consist of a single lens, which can be shifted parallel to the optical axis of the imaging system. Usually, however, lens imaging systems with several individual lenses are used.
Since the imaging optics of the inventive optical imaging system reproduce not the object itself, which usually is three dimensional, but the two-dimensional interim i
Epps Georgia
Norris & McLaughlin & Marcus
Spector David N.
Zbig Vision Gesellschaft fur neue Bildgestaltung mbH
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