Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2002-12-04
2004-04-27
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06726326
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement of an observation apparatus such as an operation microscope or a slit lamp.
2. Description of the Related Art
An operation microscope as an observation apparatus as shown in
FIG. 1
is known in the prior art. In
FIG. 1
, reference numeral
1
denotes a support post,
2
denotes a support arm, and
3
denotes a bracket for attaching an operation microscope which is mounted to the end portion of the support arm.
The support arm
2
is composed of an L-shaped arm
4
and an swinging arm
5
. The L-shaped arm
4
is attached to the top end portion of the support arm
2
such that it can be horizontally rotated. The swinging arm
5
is biased upward by a spring provided in the inner portion thereof.
An arm
6
which is held so as to be horizontally rotatable and extends downward is provided to the end portion of the swinging arm
5
. The bracket
3
is attached to the arm
6
.
An operation microscope
10
is attached to the bracket
3
. The operation microscope
10
has a body tube
11
. An observation optical system is provided in the body tube
11
. An eyepiece lens body tube
11
′ is provided to the body tube
11
.
The operation microscope
10
has, for example, an illumination optical system
12
and an observation optical system
13
as shown in FIG.
2
. The illumination optical system
12
is composed of an illumination light source
14
, a condenser lens
15
, an illumination field stop
16
, a collimator lens
17
, and a prism
18
. Reference symbol
18
b
denotes a reflection surface of the prism
18
. Illumination light from the illumination light source
14
is guided to an objective lens
19
used common to the observation optical system
13
via the condenser lens
15
, the illumination field stop
16
, the collimator lens
17
, and the prism
18
. Then, it is guided to, for example, an eye fundus Er of an operating eye E so that the eye fundus Er is illuminated. Note that reference symbol Ea denotes a pupil of the operating eye, Eb denotes an iris, and Ec denotes a cornea.
The observation optical system
13
is composed of a right-eye observation optical system
13
a
and a left-eye observation optical system
13
b
as shown in FIG.
3
. The right-eye observation optical system
13
a
includes a variable power lens system (zoom lens system)
20
composed of lenses
20
a
,
20
b
,
20
c
, a beam splitter
21
, an imaging lens
22
, an image erecting prism
23
, an interpupillary distance adjustment prism
24
, a field stop
25
, and an eyepiece
26
. Note that reference symbol
2
a
1
denotes an entrance pupil and
26
a
denotes an eye point.
Similarly, the left-eye observation optical system
13
b
includes a variable power lens system (zoom lens system)
30
composed of lenses
30
a
,
30
b
,
30
c
, a beam splitter
31
, an imaging lens
32
, an image erecting prism
33
, an interpupillary distance adjustment prism
34
, a field stop
35
, and an eyepiece
36
. Note that reference symbol
2
b
1
denotes entrance pupil and
36
a
denotes an eye point.
The reflected light from the eye fundus Er of the eye to be examined E is guided to an eye of an operator through optical members from the object lens
19
of both the observation optical systems
13
a
and
13
b
to the eyepieces
26
and
36
so that the operator observes the eye fundus Er. A portion of the reflected light from the eye fundus Er is split by the beam splitters
21
and
31
and guided to an auxiliary observation optical system
40
for an assistant operator and a TV image pickup system
50
.
In
FIG. 3
, reference numerals
41
and
51
are imaging lenses,
42
and
52
are reflection mirrors,
43
denotes an eyepiece, and
53
denotes a TV camera. The TV camera
53
has a CCD image pickup element as an image receiving means
53
a.
As shown in
FIG. 4
, an exit pupil
18
a
of the illumination optical system
12
is disposed in proximity to observation paths
2
a
2
and
2
b
2
of both the observation optical systems
13
a
and
13
b
. In
FIG. 4
, reference symbol “O” denotes an optical axis of the objective lens
19
, O
1
denotes an observation optical axis of the left-eye observation optical system
13
a
, and O
2
denotes an observation optical axis of the right-eye observation optical system.
By the way, there is a case where it is desired to observe an eye fundus and its vicinities using such a kind of operation microscope. In such a case, as shown in
FIG. 5
, optical members such as a prism or lens, contact prism or contact lens (hereinafter referred to as “optical members”)
60
are held against the cornea Ec of the eye to be examined E, thereby observing a vicinity portion Er′ of the eye fundus Er. In
FIG. 5
, such optical members
60
having an apical angle &thgr; (for example, 45 degrees) are held against the cornea Ec.
Thus, when such optical members
60
are held against the cornea Ec, the optical axis “O” of the objective lens
19
, an illumination optical axis O′ of the illumination optical system
12
, and the observation optical axes O
1
and O
2
of both the observation optical systems
13
a
and
13
b
are refracted so that the eye fundus vicinity portion Er′ of the eye fundus is observed. When the apical angle &thgr; of optical members
60
are varied as appropriate, an observation site of the eye fundus vicinity portion Er′ can be changed as appropriate.
However, when the eye fundus vicinity portion Er′ is observed using optical members
60
, astigmatism and chromatic aberration are caused by a refraction and dispersion action of light.
FIG. 6
is a schematic diagram of astigmatism in a state in which optical members
60
are not held against the operating eye E. The abscissa indicates the amount of defocus when a focusing position is assumed as an origin point and defocusing is made forward and backward. The ordinate indicates a size and a shape of a point image Q at positions corresponding to the respective amounts of defocus. When optical members
60
are not held against the cornea Ec, even if the amount of defocus become large relative to the focusing state, the point image Q is kept in substantially a circular shape. In contrast to this,
FIG. 7
is a schematic diagram of astigmatism in a state in which optical members
60
are held against the operating eye. The abscissa indicates the amount of defocus when defocusing is caused forward and backward. The ordinate indicates a size and a shape of the point image at positions corresponding to the respective amounts of defocus.
When optical members
60
are held against the cornea Ec, the astigmatism is caused. That is, a position at which the point image Q becomes circular in shape is shifted from the focusing position and it shape transforms from a longitudinal elliptical shape to a transverse elliptical shape via a minimum circle as the focusing state is changed from a focusing position front side to a focusing position back side.
Also,
FIG. 8
is a schematic diagram of astigmatism and chromatic aberration in a state in which optical members are not held against the operating eye. The abscissa indicates the amount of defocus when the focusing position is assumed as an origin point and defocusing is caused forward and backward. The ordinate indicates a size and a shape of the point image Q at positions corresponding to the respective amounts of defocus. When optical members
60
are not held against the cornea Ec, even if the amount of defocus become large relative to the focusing state, the point image Q is kept in substantially a circular shape. Also, almost no chromatic aberration whereby an image is separated among R, G, and B is observed. It is observed only slightly as the amount of defocus increases. Thus, almost no practical problem is caused in the case of the observation in the focusing position.
In contrast to this,
FIG. 9
is a schematic diagram of astigmatism and chromatic aberration in a state in which optical members
60
are held against the operating eye Ec. The ab
Aeba Hidetaka
Fukuma Yasufumi
Armstrong Kratz Quintos Hanson & Brooks, LLP
Kabushiki Kaisha Topcon
Manuel George
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