Optical: systems and elements – Compound lens system – Microscope
Reexamination Certificate
1998-08-13
2001-10-16
Nguyen, Thong (Department: 2872)
Optical: systems and elements
Compound lens system
Microscope
C359S368000, C359S376000
Reexamination Certificate
active
06304374
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a stereomicroscope.
b) Description of the Prior Art
Stereoscopic microscopes which permit observing conditions of minute locations on objects in three dimensions are widely used for research, inspections, surgical operations and so on. In recent years where sophisticated techniques are prevailing in a variety of fields, it is strongly desired to obtain a stereoscopic microscope which permits observation for a long time by two persons in relaxed postures while performing works on an object from any desired directions.
As a conventional example of stereoscopic microscopes, there is known a stereoscopic microscope which was disclosed by Japanese Patent Kokai Publication No. Hei 4-156,412. This stereoscopic microscope has a composition which consists, as illustrated in
FIG. 1
, of an objective lens system
2
, an afocal optical system
3
disposed coaxially with the objective lens system
2
and at least a pair of eyepiece optical systems
15
. The stereoscopic microscope is configured so as to satisfy the desire described above by configuring the eyepiece optical systems
15
as a whole so as to be rotatable around an axis which is located in parallel with optical axes of the objective lens system
2
. In
FIG. 1
, the reference numeral
16
represents eyes of observers and the reference numeral
17
designates optical path splitting elements disposed in the eyepiece optical systems
15
.
In the case of the stereoscopic microscope illustrated in
FIG. 1
, however, the afocal variable magnification optical system must have a diameter of an exit pupil thereof which is large enough to cover right and left pupils for observation of the eyepiece optical systems
15
. However, a stereoscopic microscope generally uses two afocal variable magnification systems. In order to enlarge a diameter of one of the two afocal variable magnification optical systems so that light bundles are incident on the two right and left eyepiece optical systems, the diameter of the exit pupil of the variable magnification optical system must be made at least double in size, whereby the afocal variable magnification optical system inevitably has a length at least two times larger than a length of each of the two afocal variable magnification optical systems. As a result, the stereoscopic microscope has a prolonged total length or a length as measured from an object to be observed to an eyepiece lens component, thereby making it rather inconvenient to perform works on and in the vicinity of a surface of the object while peeping through the eyepiece lens system.
Further, when a total length of the variable magnification optical systems is shortened without changing the enlarged diameter of the exit pupil, focal lengths of respective lens components are shortened, thereby making it difficult to manufacture the lens components with high precision in practice and adjust locations of the lens components accurately at a stage of assembly of the afocal variable magnification optical systems.
For the reason described above, it has conventionally been difficult to obtain a stereoscopic microscope comprising an objective lens system and a variable magnification optical system which are disposed on a common optical axis, and permitting performing works on a surface of an object while observing an image thereof as described above.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a stereoscopic microscope which uses a single vary-focal optical system, and which is configured so as to have a short length from a surface of an object to an eye point, and which features a merit to perform work on the object.
Another object of the present invention is to provide a stereoscopic microscope which is of the type described above and uses a compact variable magnification optical system having favorable optical performance.
The stereoscopic microscope according to the present invention comprises an objective lens system and a vary-focal optical system which are disposed consecutively on a common optical axis, has a plurality of pupils in a light bundle emerging from the variable magnification optical system, and is configured so as to have a length as measured from an object to be observed to an eye point which is shortened by deflecting the light bundle by using two or more reflecting members in the variable magnification optical system.
Speaking more concretely, the stereoscopic microscope according to the present invention comprises the objective lens system, the vari-focal optical system which is disposed coaxially with the objective lens system and eyepiece optical systems; permits observing a three-dimensional image of an object while leading rays which are apart from the optical axis, out of rays coming from the object and passing through the objective lens system and the variable magnification optical system, to right and left eyes of an observer through the eyepiece optical systems; and is configured so as to shorten a length as measured from the object to the eyes of the observer by deflecting an optical path in the variable magnification optical system by using at least two reflecting members in the variable magnification optical system.
In the stereoscopic microscope according to the present invention, the vari-focal optical system is composed of a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power; and the first lens unit and the second lens unit are moved along the optical axis for changing a magnification of the stereoscopic microscope.
For configuring the optical system comprised in the stereoscopic microscope according to the present invention so as to be compact, it is necessary to strengthen the refractive powers of the lens units which are to be used for composing the variable magnification optical system. When the refractive powers of the lens units are strengthened in the variable magnification optical system which is composed of the first lens unit having the positive refractive power, the second lens unit having the negative refractive power and the third lens unit having the positive refractive power, the second lens unit in particular has a strong negative refractive power and a location of an image formed by the stereoscopic microscope is deviated due to indication and/or eccentricity of the second lens unit. Such an adverse influence is produced remarkably in particular due to inclinations and eccentricities of movable lens units. For this reason, the magnification of the stereoscopic microscope according to the present invention is changed by moving the first lens unit and the second lens unit, with the second lens unit having the strong refractive power kept stationary so as to prevent an adverse influence from being produced by moving the second lens unit. Further, it is necessary to use a lens barrel and moving mechanisms which are manufactured with high precisions for minimizing the inclinations and eccentricities of the movable lens units. The stereoscopic microscope according to the present invention, in which the second lens unit having the strong refractive power is kept stationary, permits simplifying structures of the lens barrel and moving mechanisms.
Furthermore, the stereoscopic microscope according to the present invention permits shortening the length as measured from the object to be observed to the eye point by using two reflecting members at locations which are fixed relatively to the second lens unit in the variable magnification optical system.
REFERENCES:
patent: 3030857 (1962-04-01), Shumway
patent: 4634241 (1987-01-01), Kohayakawa et al.
patent: 4647845 (1987-03-01), Richter et al.
patent: 4710000 (1987-12-01), Spitznas et al.
patent: 4798451 (1989-01-01), Fujiwara
patent: 5227914 (1993-07-01), Hanzawa et al.
patent: 5543962 (1996-08-01), Kitajima et al.
patent: 3718843 (1987-12-01), None
patent: 214223 (1989-10-01), None
patent: 412379 (1992-02-01), Non
Nguyen Thong
Olympus Optical Co,. Ltd.
Pillsbury & Winthrop LLP
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