Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Reexamination Certificate
1999-04-29
2003-06-10
Robinson, Mark A. (Department: 2872)
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
C359S015000, C351S168000
Reexamination Certificate
active
06577411
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to an optical system for alternative or simultaneous direction of light originating from two scenes to an eye of a viewer, and more particularly, to an optical system which employs a planar opyics approach for alternative or simultaneous direction of light originating from two scenes to the eye of a viewer. The system according to the invention may thus be used to provide inventive bifocal eyeglasses, using which does not require inconvenient head and eye positioning relative to the viewed scene as associated with using conventional bifocal eyeglasess. The present invention further relates to an optical system for simultaneous direction of light originating from two scenes to an eye or both eyes of a viewer using geometric or planar optic approaches. The system according to the invention does not employ active radiation for display.
As used herein in the specification and claims, the term ‘scene’ refers to an object or set of objects as perceived by a viewer through passive radiation, i.e., through radiation which comes from outside the system of the present invention.
The passive radiation may for example be radiation reflected or scattered by the object or objects and it may also be radiation which is emitted from the object or objects. In other words, passive radiation is radiation which comes from outside the system of the present invention and which would have perceived by the viewer even without the system of the present invention.
By contrast, the term ‘active radiation’ as used herein is intended to include radiation which originates from a component of the system in question. Thus, for example, a conventional head-up-display (HUD) system includes a cathode ray tube (CRT), so that the radiation generated by the CRT is active radiation. A view of active radiation as herein defined is defined herein as a display.
The term ‘scene’ as referred herein specifically excludes any type of a display formed by active radiation, as used for example in HUD systems. The term ‘image’ as used herein reads upon both scene and display, whereas a real image refers to a scene and a virtual image refers to a display.
Since the system of the present invention includes no source of radiation, all the radiation perceived by the viewer using the system of the present invention is passive radiation. It is to be noted that, as defined herein, in the context of the present invention, even radiation which is emitted, for example, from a television screen or computer monitor, is considered passive radiation since neither the television screen nor the computer monitor is a part of the system of the present invention.
A high percentage of the population is in need of eyeglasses due to various vision defects.
Conventional eyeglasses typically include a frame to support the glasses in a suitable position in front of the eyes of the viewer, and two lenses implemented within the frame, one for each of the eyes of the viewer. Each of the lenses is acquired a focal characteristic to compensate for its specific eye vision defect.
Thus for example, in cases of myopia, which is a vision defect of focus, resulting from too much power in the eye lens and cornea and/or too long an eyeball, the image of a distant object falls ahead of the retina and cannot be focused sharply due to extensive amount of positive focal power, a negative lens is chosen so that its image is formed at the most distant point on which the myopic eye can focus.
On the other hand, in cases of hyperopia, the reverse of myopia which results from too little power in the refracting elements of the eye and/or too short an eyeball, the image of a distant object is formed (when the eye is relaxed) behind the retina. Hyperopia is therefore compensated for by a positive lens.
Myopia and hyperopia are vision defects associated with viewing distant objects. Presibyopia, on the other hand, is an example for a vision defect associated with viewing close objects, which in many cases impairs the ability to read. Presibyopia results from the hardening of the material of the lens which typically comes with age, and leads to a limited ability to focus (accommodate) the eye with respect to close objects. Presibyopia is therefore compensated for by a positive lens which enables a user to comfortably read.
However, in many cases a single eye suffers from both a long distance vision defect such as myopia or hipermyopia limiting its landscape vision capabilities and a short distance vision defect such as presibyopia limiting its reading capabilities.
A person with such a dual eye defect is in need of either two sets of eyeglasses, the first offers corrective optics for the long distance vision defect and the other offers corrective optics for the short distance vision defect, or alternatively, a set of what is known in the art as bifocal eyeglasses which include bifocal lenses, each is in fact the combination of two lenses having given (yet different) focal lengths and optical characteristics, arranged one aside the other. Multifocal eyeglasses are also known although less frequently used due to their high price and the inability of many individuals to accommodate to their use.
Nevertheless, both these solutions suffer limitations. Using two pairs of eyeglasses, one pair for reading and the other for long distance viewing, requires changing the glasses each time a user moves his site from a close to a distant object, and wise versa. Using bi- or multifocal eyeglasses dictates different lines of site for viewing close and distant objects and limits the field of view in both cases. Typically, for reading the user is required to lower his eyes while maintaining a substantially straight forward head position. Should the close object be positioned straight ahead relative to the viewer, in order to sharply view the close object, the viewer is required to tilt his head backwards and at the same time to lower his eyes. All this leads in many cases to head and neck problems, which is the reason why many individuals prefer not to use bifocal eyeglasses.
There is thus a widely recognized need for, and it would be highly advantageous to have, an optical system for alternative or simultaneous direction of light originating from two scenes to the eye of a viewer, as such a system can be used to provide bi- or multi focal eyeglasses, using which does not require inconvenient head and eye positioning relative to the viewed scene.
Many situations exist in which a viewer is interested in viewing scenes located in different locations with respect to the viewer. Examples include but are not limited to (i) taking notes while viewing a blackboard, a lecturer or a display (e.g., a slides screen), in this case the viewer is interested at viewing both his notes, which are typically located on a table or a writing board, and the blackboard, lecturer or display; (ii) drawing while viewing the object to be drawn (e.g., landscape), in this case the viewer is interested at viewing both his drawing board and the drawn object; (iii) typing on a keyboard while viewing the screen, in this case a non professional typist is interested at viewing both the keyboard and the screen; (iv) locking at or reading from a printed matter (e.g., a map, a guide book, etc.) while viewing another scene (e.g., a road, an instrument, etc.), in this case the viewer is interested at viewing both the printed matter and the other scene.
However, since the field of view in which a viewer can focus is relatively narrow, in the above and similar situations the viewer is required to move his eyes site back and forth between the scenes, such that at any given time the viewer sees only one of the scenes. This in turn creates disadvantages since (i) when the viewer sees one scene he may not become aware to a change in the other scene, thus for example, a driver or a pilot, while viewing a road or navigation map, cannot at the same time view the road or sky ahead; and (ii) the viewer finds it difficult to compare between scenes, thus for the painter it is di
Amari Alessandro V.
Friedman Mark M.
Planop-Planar Optics Ltd.
Robinson Mark A.
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