Optical: systems and elements – Lens – Microscope objective
Reexamination Certificate
1999-09-13
2001-11-06
Lester, Evelyn A (Department: 2873)
Optical: systems and elements
Lens
Microscope objective
C359S376000, C359S377000, C359S378000, C359S380000, C359S672000, C359S676000
Reexamination Certificate
active
06313952
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a stereomicroscope, and in particular to an adapter lens system for a Greenough-type stereomicroscope.
BACKGROUND OF THE INVENTION
A stereomicroscope permits observation with the same three-dimensional comprehension as that provided by both eyes while a solid object is being observed. Therefore, it is easy to obtain a perspective relation between a tool, such as tweezers, and an object while working in an image field of a stereomicroscope. Thus, a stereomicroscope is especially effective in applications requiring minute manipulation such as precision machining, dissection in biological research and surgical operations. To obtain parallax for three-dimensional comprehension with a stereomicroscope, portions of the optical elements through which light rays pass to enter into both right and left eyes of the observer are independent of each other. The two rays which enter both eyes are made to intersect in the plane of the object being observed. The enlarged images viewed from different directions are formed and are observed through the eyepieces of the microscope, allowing stereovision of a small object under observation. This type of stereomicroscope is known as “Greenough-type” stereomicroscope. The Greenough-type stereomicroscope is one of the standard stereomicroscopes used for obtaining a stereovision of an object.
FIG. 4
is a schematic diagram of a Greenough-type stereomicroscope SM
1
according to related art. Stereomicroscope SM
1
comprises an optical system OSR for the right eye and the optical system OSI for the left eye. The respective optical axes AX
1
and AX
2
of optical systems OSL and OSR are arranged at a predetermined angle &thgr; and intersect at optical axis AX
0
bisecting optical axes AX
1
and AX
2
. An image of an object
1
arranged at the intersection of optical axes AX
1
and AX
2
is formed at positions
7
and
7
′ by imaging lenses (usually zoom lens)
6
and
6
′ having a magnification &bgr;. The magnification B of optical systems OSL and OSR from object
1
to images
7
and
7
′ is &bgr;. Images
7
and
7
′ are then magnified respectively by eyepiece lenses
8
and
8
′, and are observed by the naked eyes of an operator (not shown) of the microscope placed at eyepoint positions
9
and
9
′ respectively.
In a Greenough-type stereomicroscope, for an individual to observe an object in a free and comfortable posture, it is necessary to change the position of eye-points
9
and
9
′ of the eyepiece along respective optical axes AX
1
and AX
2
, to the eye-level of the observer, which in part depends on the height of the observer. To raise the eye-level, the distance between object
1
and eye-points
9
and
9
′ needs to increase. On the other hand, to lower the eye-level, the distance between object
1
and eye-points
9
and
9
′ needs to decrease. In a Greenough-type stereomicroscope, use of an auxiliary objective lens is a known method for changing the eye-level.
FIGS. 5 and 6
demonstrate the known method of changing eye-level using an auxiliary objective lens. The stereomicroscopes in
FIGS. 5 and 6
are constructed the same as that in FIG.
4
and the same reference numbers are used to identify parts equivalent to those in FIG.
4
.
FIG. 5
provides a schematic diagram of the optical system using, the currently known method for raising the eye-level of a Greenougih-type stereomicroscope. As depicted in
FIG. 5
, by inserting an auxiliary objective lens
14
(shown as a negative lens) between object
1
and imaging lenses
6
and
6
′, the distance from object
1
to the imaging lenses is extended and the eye-level is raised. In
FIG. 5
, P
1
denotes the position of object
1
when auxiliary objective lens
14
is not inserted, and P
3
denotes the position of the object when the auxiliary objective lens is inserted. Also, D41 denotes the axial distance between object
1
at position P
1
and a principal plane
14
h
(principal point) when auxiliary objective lens
14
is not inserted. D43 denotes the distance between position P
3
of object
1
and principal plane
14
h
(principal point) when auxiliary objective lens
14
is inserted. D13 denotes the distance between position P
1
of object
1
when auxiliary objective lens
14
is not inserted, and position of P
3
when auxiliary objective lens
14
is inserted. Since auxiliary objective lens
14
is inserted between object
1
and imaging lenses
6
and
6
′, the distance from the object to imaging lenses
6
and
6
′ is extended by moving the position of the object observed from position P
1
to P
3
, raising the eye-level. In this configuration, the eye-level is raised by the amount D13 by inserting auxiliary objective lens
14
. Position P
1
and P
3
are along optical axis AX
0
.
The magnification &bgr;a of auxiliary objective lens
14
is determined by the following equation:
&bgr;a=(D41/D43)<1.
The magnification B from object
1
at position P
3
to images
7
and
7
′ is given as:
B=&bgr;a×&bgr;.
FIG. 6
is a schematic diagram showing the currently known optical system used in stereomicroscope SM
1
for lowering the eye-level. As depicted in
FIG. 6
, an auxiliary objective lens
15
(shown as positive lens) is inserted between object
1
and imaging lenses
6
and
6
′. This decreases the distance from object
1
to imaging lenses
6
and
6
′, thus lowering the eye-level. In
FIG. 6
, P
1
denotes the position of object
1
when auxiliary objective lens
15
is not inserted, and P
3
denotes the position of the object when auxiliary objective lens
15
is inserted. D41 denotes the distance between object
1
at position P
1
and a principal plane
15
h
(principal point) when auxiliary objective lens
15
is not inserted. D43 denotes the distance between object
1
at position P
3
and principal plane
15
h
(principal point) when auxiliary objective lens
15
is inserted. D31 denotes the distance between the position P
1
of object
1
when the auxiliary objective lens
15
is not inserted and position P
3
of the object when auxiliary objective lens
15
is inserted. When auxiliary objective lens
15
(positive lens) is inserted between object and imaging lenses
6
and
6
′, the distance from the object to the imaging lenses is decreased, lowering, the eye-level. In this configuration, the eye-level can be lowered by the amount of D31 by inserting auxiliary objective lens
15
.
The magnification &bgr;a of auxiliary objective lens
15
is determined by the following equation:
&bgr;a=(D41/D43)>1.
The magnification B from the object
3
to the images
7
and
7
′ is given by:
B=&bgr;a×&bgr;.
As is described above, according to related art, to adjust the eye-level either up or down to the height of an observer looking through the Greenough-type stereomicroscope, one must change the auxiliary objective lens each time. This is cumbersome, prevents quick observations in different positions, and disrupts careful observations, as changing the auxiliary lenses can jar the object under observation.
SUMMARY OF THE INVENTION
It is a goal of the present invention, in view of the above problems, to provide an Greenough-type stereomicroscope having a simple construction which provides a user of the microscope with the ability to change eye-level over a continuous range of positions during use of the microscope without interruption.
It is yet another goal of the present invention to provide an adapter lens for a stereomicroscope which can be attached to the objective lens side of the microscope, allowing the user of the microscope to adjust the height of the eye pieces, while continuing observations with the microscope without changing lenses.
The present invention accomplishes these and other goals by providing an adapter lens attachable to an objective lens side of a Greenough-type stereo microscope, the adapter lens having in order from the Greenough-type stereo microscope's objec
Lester Evelyn A
Nikon Corporation
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