Optical: systems and elements – Lens – Panoramic
Reexamination Certificate
2002-03-20
2003-11-11
Sugarman, Scott J. (Department: 2873)
Optical: systems and elements
Lens
Panoramic
C359S729000
Reexamination Certificate
active
06646818
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a panoramic imaging lens capable of imaging a lateral perspective of 360° circumference as an annular image.
2. Description of the Related Art
As a panoramic imaging lens that can image a perspective of 360° circumference at one time, lenses disclosed in U.S. Pat. Nos. 4,566,763 and 5,473,474 have been conventionally known. The panoramic imaging lens
1
is formed with a light permeable material, such as optical glass, a transparent resin and the like, in a rotation symmetrical form around a light axis, which is a central axis of the lens as shown in FIG.
1
. The panoramic imaging lens
1
has an annular light incident surface
2
, on which lateral light from the 360° full circumference is incident; a first reflective surface
3
formed in an annular form that is adjacent to and substantially opposes the light incident surface
2
to reflect the light inside the lens
1
; and a second reflective surface
4
provided at a central part inside the annular light incident surface
2
to reflect the reflected light from the first reflective surface
3
inside the annular first reflective surface
3
. A light outgoing surface
5
transmitting the light from the second reflective surface
4
is formed at a position opposing the second reflective surface
4
in a central part of the first reflective surface
3
. The light incident surface
2
is formed in a form of a convex lens bulging laterally, and the second reflective surface
4
inside it is formed in a concave form, whereby the inner surface of the lens
1
is a reflective surface in a form of a convex mirror. The first reflective surface
3
adjacent to the light incident surface
2
is also formed in a form of a convex surface bulging laterally, and the inner surface of the lens
1
is an annular reflective surface of a concave mirror form directed to the second reflective surface
4
. The light outgoing surface
5
is appropriately formed in a concave or convex surface or a planar surface.
A panoramic imaging system using the panoramic imaging lens
1
comprises, as shown in
FIG. 1
, a panoramic imaging adapter
10
having the panoramic imaging lens
1
and a relay lens
6
for image formation provided on the light axis, and an imaging device
8
, such as a video camera and the like, to which the panoramic imaging adapter
10
is attached. The imaging device
8
comprises a lens system
9
for acquiring an image, an imaging element
7
, such as a CCD and the like, provided at the image focus location thereof, and a necessary controlling sections and the like not shown in the figure.
A panoramic landscape
11
of 360° circumference acquired by the panoramic imaging lens
1
is converted to an electric signal by the imaging element
7
of the imaging device
8
and projected on various kinds of a monitoring device
14
, such as a liquid crystal, a CRT and the like.
With respect to the panoramic imaging lens
1
, in the case where the panoramic imaging adapter
10
is arranged in such a direction that the light incident surface
2
turns upward as shown in
FIG. 1
, the lowermost light L
1
from the panoramic landscape
11
of 360° circumference amongst the incident light incident on the light incident surface
2
of the panoramic imaging lens
1
is refracted at the light incident surface
2
, then reflected at the opposing first reflective surface
3
toward the second reflective surface
4
, and further reflected at the second reflective surface
4
to outgo from the light outgoing surface
5
, followed by being imaged through the relay lens
6
on a circumferential part of the imaging element
7
. In the case where the uppermost light L
2
from the panoramic landscape
11
amongst the incident light is incident on the light incident surface
2
, it is reflected at the light incident surface
2
of the panoramic imaging lens
1
, then reflected at the opposing first reflective surface
2
toward the second reflective surface
4
, and further reflected at the second reflective surface to outgo from the light outgoing surface
5
, followed by being imaged through the relay lens
6
on a central part of the imaging element
7
. According to the foregoing mechanisms, the panoramic landscape
11
is imaged in an annular form on the imaging element
7
and projected as an annular two-dimensional image
12
on the monitoring device
14
.
According to the foregoing conventional technique, there is such a problem that a part of the light incident on the light incident surface
2
of the panoramic imaging lens
1
is incident on the imaging element
7
as flare and ghost. The phenomenon of flare or the like is caused by mixing external noise light Ln functioning as flare or the like with the regular imaging light LO on the light path inside the lens as shown in FIG.
2
A. The noise light Ln is incident on the light incident surface
2
of the panoramic imaging lens
1
, and after reflected on the first reflective surface
3
and the second reflective surface
4
inside the panoramic imaging lens
1
, most of the noise light Ln again outgoes from the light incident surface
2
as shown in FIG.
2
A. However, a slight part of the noise light Ln
1
amongst the noise light Ln is inwardly reflected on the light incident surface
2
inside the panoramic imaging lens
1
and proceeds to agree with the light path of the regular imaging light L
0
in the lens. Therefore, the noise light Ln
1
, which is a part of the noise light Ln, is inwardly reflected on the light incident surface
2
, and then it agrees with the light path of the regular imaging light L
0
to reach the imaging element
7
, and is projected as flare and ghost.
The invasion path of the noise light Ln includes, in addition to the foregoing, noise light Ln
2
causing flare or the like that suffers repeated reflection inside the panoramic imaging lens
1
and then agrees with the incident path of the regular imaging light L
0
by the inward reflection on the light incident surface
2
as shown in FIG.
2
B. Moreover, as shown in
FIG. 2C
, noise light Ln
3
causing flare or the like is included, which after reflected once inside,the panoramic imaging lens
1
, agrees with the incident light path of the regular imaging light L
0
by the inward reflection on the light incident surface
2
.
With respect to the flare and ghost, partial strong light is particularly liable to function as the noise light Ln when light is incident on the panoramic imaging lens
1
from the 360° circumference. In the case where the panoramic imaging system is used as a surveillance camera or the like, there is such a problem and the like that the flare and ghost adversely affect the control of light amount to deteriorate quality of the pictured image.
SUMMARY OF THE INVENTION
The invention has been developed in view of the foregoing problems associated with the conventional technique, and an object thereof is to provide a panoramic imaging lens capable of certainly suppressing noise light causing flare and ghost with a simple structure.
Specifically, the invention relates to a panoramic imaging lens comprising a light transmitting material, such as optical glass, a transparent resin and the like, and comprising an annular light incident surface formed in a rotation symmetrical form around a light axis, which is a central axis of the lens in a substantial convex lens form bulging to enable incident of lateral light from the 360° full circumference; afirst reflective surface formed in an annular concave mirror form bulging outwardly that substantially opposes the light incident surface to reflect light inside the lens; a second reflective surface formed in a convex mirror form provided at a central part inside the annular light incident surface to reflect the reflected light from the first reflective surface toward an inner part of the annular first reflective surface; and a light outgoing surface positioned at a central part inside the annular first reflective surface and opposing the second reflective surface to tran
Kubovcik & Kubovcik
Raizen Deborah
Sugarman Scott J.
Tateyama R&D Co., Ltd.
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