Panoramic refracting optic

Details Panoramic refracting optic Panoramic refracting optic

2000-07-28

2002-07-23

Schwartz, Jordan M. (Department: 2873)

Optical: systems and elements

Lens

Panoramic

C359S727000

Reexamination Certificate

active

06424470

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to optical devices. More specifically, the invention is an optical device capable of achieving a semi-spherical or hemispherical field-of-view.
2. Description of the Related Art
Imaging or illuminating cylindrical, semi-spherical or hemispherical scenes is generally accomplished using a plurality of angular field-of-view cameras/lenses positioned to characterize the necessary field-of-view. Typically, the angular field-of-view of each camera/lens is on the order of 120° or less. Thus, multiple cameras/lenses are required to simultaneously view or illuminate, for example, the traffic flow at an intersection, the entire area surrounding a vehicle or structure, or the interior of a room or other structure.
A solution to this problem is a camera/lens having the ability to image or illuminate annularly thereabout, i.e., over an entire 360° field-of-view. One such device is a panoramic annular lens (PAL) available commercially from Optechnology Incorporated, Gurley, Ala. The PAL provides a cylindrical or flat annular image about an observation point. A two-dimensional diametrical view of the PAL is shown in FIG.
1
and is referenced generally by
10
. Accordingly, the three-dimensional solid structure of a PAL can be visualized by rotating PAL
10
about the Z-axis which passes through the central axis of PAL
10
.
The two-dimensional representation of the flat annular image plane of PAL
10
is represented by lines
12
and
14
. That is, PAL
10
can be used to image objects on either of lines
12
and
14
. For example, the image path for an object on line
12
is indicated by path lines
16
A-
16
D. Path
16
A indicates light traveling from line
12
(e.g., the surface of a cylindrical object) to a convex surface
10
A of PAL
10
. Path
16
B indicates refracted light traveling from convex surface
10
A through PAL
10
to a convex surface
10
B. Convex surface
10
B is internally reflective so that path
16
C indicates reflected light traveling from the reflective convex surface
10
B through PAL
10
to a reflective concave surface
10
C. Path
16
D indicates reflected light traveling from concave surface
10
C through PAL
10
to a flat clear surface
10
D, at which point light exits PAL
10
. Note that a similar set of path lines could be drawn for an object on line
14
with light entering PAL
10
at convex surface
10
E and being reflected at convex surface lOF.
Unfortunately, the three-dimensional realization of a lens based on the two-dimensional diametrical geometry of PAL
10
is difficult to machine with acceptable tolerances. Thus, the PAL based on the two-dimensional geometry described above is limited to use in expensive systems that can tolerate its high-cost of precision manufacturing. Further, the PAL's forward-looking angular resolution along the Z-axis is limited due to the presence of concave surface
10
C.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an optical device capable of being used to image or illuminate a 360° field-of-view.
Another object of the present invention is to provide an optical device having a field-of-view that is semi-spherical or hemispherical.
Still another object of the present invention is to provide a 360° field-of-view optical device of simple construction.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, an optical device has at least a semi-spherical field-of-view. The device comprises a conically-shaped piece of optical material having an annular surface satisfying Snell's Law for total internal reflection with respect to light passing through the piece and incident on the annular surface from within the piece. The annular surface is symmetric about the device's longitudinal axis with its exterior being concave.


REFERENCES:
patent: 5473474 (1995-12-01), Powell
patent: 6115193 (2000-09-01), Shu
patent: 6175454 (2001-01-01), Hoogland et al.

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