VIEW EXPANDING AND DIRECTING OPTICAL SYSTEM
First Claim
1. A view expanding and directing optical unit comprising the combination of optical elements including a Fresnel lens having a negative focal length and a Fresnel prism, said lens and prism located adjacent one another and arranged to intersect a desired line of sight to provide to a person viewing along said line of sight an expanded field of view in which the objects in said field of view are demagnified;
- said optical elements each including a grooved and a generally flat side;
the generally flat side of one of said otpical elements facing away from said other optical element.
1 Assignment
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Accused Products
Abstract
A view expanding and directing optical system for use in viewing around obstacles and the like comprising in combination a negative Fresnel lens and a Fresnel prism disposed in separate planes immediately adjacent one another. In the preferred embodiment, the system is mounted on a vehicle, at the rear thereof, whereby the system provides an expanded and demagnified viewing area to the rear of and below the level of the rear window and/or laterally of the vehicle. In other embodiments, the system may be coupled to means for extending or retracting it at desired times, and may be used in conjunction with vision aiding elements, such as a rearview periscope, for providing an expanded and demagnified viewing area laterally and to the rear of the vehicle.
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Citations
9 Claims
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1. A view expanding and directing optical unit comprising the combination of optical elements including a Fresnel lens having a negative focal length and a Fresnel prism, said lens and prism located adjacent one another and arranged to intersect a desired line of sight to provide to a person viewing along said line of sight an expanded field of view in which the objects in said field of view are demagnified;
- said optical elements each including a grooved and a generally flat side;
the generally flat side of one of said otpical elements facing away from said other optical element.
- said optical elements each including a grooved and a generally flat side;
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2. An optical unit as described in claim 1 wherein said generally flat sides of both said optical elements face away from each other respective optical element.
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3. An optical system for expanding a field of view and for viewing around obstacles and the like comprising in combination:
- a Fresnel lens having a negatIve focal length and a prism having a specified angle of deviation of incident light rays;
adjacent said lens and prism positioned adjacent one another whereby the viewing area visible through said system is expanded and are the objects in said viewing area. demagnified said Fresnel lens including lens sections having aspherical surfaces.
- a Fresnel lens having a negatIve focal length and a prism having a specified angle of deviation of incident light rays;
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4. An optical system as described in claim 3 wherein said prism is a Fresnel prism having a specified angle of deviation of incident light rays.
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5. An optical system as described in claim 4 wherein said Fresnel lens is a rotationally optically symmetrical Fresnel lens, said rotational optical symmetry being defined with respect to a central rotational axis perpendicular to said plane including said lens, said axis passing through the opitcal center of said lens.
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6. An optical system as described in claim 3 wherein said Fresnel lens is an off-axis Fresnel lens section having a predetermined degree of optical asymmetry determining the expansion, demagnification and position of the viewing area of said lens.
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7. An optical system as described in claim 4 wherein said lens and prism each include a relatively flat side and a grooved side, said lens and prism being disposed generally parallel to one another such that said flat sides face outwardly and said grooved sides face inwardly.
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8. An optical system as described in claim 4 wherein said lens and prism are mounted adjacent and generally parallel one another in a means for adjusting the position of said system whereby the position of said expanded and demagnified viewing area with respect to an obstacle to be viewed around its selectively adjustable.
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9. An optical system as described in claim 8 wherein said means for adjusting the position of said system comprises a support means including a frame, securing means, and a base;
- said lens and prism being mounted in said frame, said frame being pivotally mounted on said base by means of said securing means with its pivot axis being parallel to said planes containing said lens and said prism such that said frame may be selectively adjustable.
Specification