Optical: systems and elements – Compound lens system – Telescope
Reexamination Certificate
1997-04-21
2001-01-09
Wells, Kenneth B. (Department: 2816)
Optical: systems and elements
Compound lens system
Telescope
C359S480000, C351S041000, C351S047000
Reexamination Certificate
active
06172805
ABSTRACT:
BACKGROUND OF THE INVENTION
It is sometimes desirable to have an optical system with multiple fields of view. For example, Grech U.S. Pat. No. 4,155,626 discloses spectacles which provide a wide angle field of view in a peripheral region and an essentially normal field of view without magnification or demagnification in a central region. Spectacles of this type are of particular advantage for individuals with tunnel vision in that the field of view can be enlarged beyond the “tunnel” which defines the normal field of view.
According to the Grech patent, a wide angle lens system is mounted on a spectacle frame and the wide angle lens system includes a central region with flat, parallel surfaces which provide unit magnification. The concept of the Grech patent is sound. However, if the flat surfaces are not aligned quite accurately with the line of sight, the observer may see several circular segments and the information received may be somewhat distorted.
SUMMARY OF THE INVENTION
This invention provides a lens system which has different fields of view in peripheral and central regions and which eliminates the need for the flat surfaces in the central regions of the lenses. With this invention, the central region includes a first lens of nonunity power and this is used in providing a different, and typically narrower field of view in the central region than exists in the peripheral region. Thus, the field of view is narrower in the central field of vision than in the peripheral field of vision.
The lens system of this invention can be put to many different uses including spectacles in which event the lens system is carried by a spectacle frame. For spectacle usage, a peripheral region of the lens system is preferably a wide angle lens system which provides a wider field of view at the peripheral region than would exist without the lens system. The lens system may also be used, for example, in a gunsight telescope, camera and in a security door viewer.
The plurality of lenses of the lens system may include a concave lens having a concave surface in which event the first lens reduces the optical power of the concave lens. The first lens may provide at least a portion of either the proximal or distal surfaces of the plurality of lenses.
Preferably the lens system includes whatever number and kind of lenses that are needed to create the desired field of view in the peripheral field of vision. Typically, these lenses are coaxially arranged. Because the first lens is provided for use in narrowing the field of view in a central field of vision, it preferably has a smaller area in a radial plane than the lenses which are used to create the desired field of view in the peripheral field of vision. In a preferred embodiment, the lens system includes at least two negative lenses and a positive lens and the first lens has a positive optical power.
A conventional gunsight telescope has an objective, an eyepiece and at least one erector lens. The lens system of this invention can be utilized in a gunsight telescope to provide a narrower field of view through the gunsight telescope in a central field of view than in a peripheral field of view. In one preferred construction, the lens system provides a greater than unity magnification in both the central and peripheral regions.
A preferred way to achieve multiple fields of view in a gunsight telescope is to have a central region of the objective lens have a longer focal length than a peripheral region of the objective lens and a central region of the erector lens have a shorter focal length than the peripheral region of the erector lens. This can be accomplished, for example, by employing a central negative objective lens surface and a positive central erector lens surface with the objective surface being a posterior surface of the objective lens and the erector surface being an anterior surface of the erector lens. If desired, a shutter can be provided for selectively blocking the peripheral field of vision while permitting light to be transmitted in the central field of vision. This can be used, for example, to block the wider angle peripheral field of vision when using the gunsight for sighting through the central region.
The invention, together with additional features and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.
REFERENCES:
patent: 1611647 (1926-12-01), Kopp
patent: 1685725 (1928-09-01), Rowe
patent: 3111675 (1963-11-01), Mora
patent: 4023892 (1977-05-01), Smith
patent: 4099849 (1978-07-01), Lawson et al.
patent: 4155626 (1979-05-01), Grech
patent: 4555164 (1985-11-01), Feinbloom
patent: 4950055 (1990-08-01), Tatsuno
patent: 4989962 (1991-02-01), Kebo
patent: 5144480 (1992-09-01), Ohshita
patent: 5161065 (1992-11-01), Ohshita
patent: 5371626 (1994-12-01), Betensky
Final Report Peripheral Vision Expander System (PVES), pp. 1-10 and Figs. 1-21, Mar. 28, 1994 prepared by Optics 1, Inc. for Department of Veterans Affairs Rehabilitation R&D Center.
Stout Donald E.
Stout, Uxa Buyan & Mullins, LLP
Wells Kenneth B.
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