U.S. patent application number 09/799407 was filed with the patent office on 2001-07-19 for optical microscope.
This patent application is currently assigned to OLYMPUS OPTICAL CO., LTD. Invention is credited to Adachi, Sadashi, Fujiwara, Masaru, Koyama, Kenichi, Tsuchiya, Atsuhiro.
Application Number | 20010008461 09/799407 |
Document ID | / |
Family ID | 26487481 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008461 |
Kind Code |
A1 |
Koyama, Kenichi ; et
al. |
July 19, 2001 |
Optical microscope
Abstract
An optical microscope has a revolver for selectively inserting a
plurality of objective lenses including a low-magnification
(very-low-magnification- ) objective lens on an optical axis for
observation light. In fluorescence observation using the
low-magnification objective lens, the effective diameter of an
observation optical system is set larger than that of an
illumination optical system. With this arrangement, fluorescence
observation using the low-magnification objective lens can be
stably performed. A cube unit having a plurality of cubes
corresponding to the respective microscopic methods is arranged in
the optical microscope. An auxiliary lens serving as a
very-low-magnification objective lens is mounted in this cube unit.
The auxiliary lens can be automatically used in observation using
the very-low-magnification objective lens. With this arrangement, a
compact optical microscope excellent in operability can be
realized.
Inventors: |
Koyama, Kenichi;
(Sagamihara-shi, JP) ; Tsuchiya, Atsuhiro; (Tokyo,
JP) ; Fujiwara, Masaru; (Ina-shi, JP) ;
Adachi, Sadashi; (Tokyo, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN &
LANGER & CHICK, PC
767 THIRD AVENUE
25TH AVE
NEW YORK
NY
10017-2023
US
|
Assignee: |
OLYMPUS OPTICAL CO., LTD
2-3, Kuboyama-cho, Hachioji-shi
Tokyo
JP
|
Family ID: |
26487481 |
Appl. No.: |
09/799407 |
Filed: |
March 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09799407 |
Mar 5, 2001 |
|
|
|
09098064 |
Jun 16, 1998 |
|
|
|
6226118 |
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Current U.S.
Class: |
359/380 ;
359/368; 359/381; 359/385 |
Current CPC
Class: |
G02B 7/16 20130101 |
Class at
Publication: |
359/380 ;
359/368; 359/381; 359/385 |
International
Class: |
G02B 021/00; G02B
021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 1997 |
JP |
9-161299 |
Jul 10, 1997 |
JP |
9-185015 |
Claims
1. An optical microscope comprising: a light source for emitting
illumination light; an illumination optical system for irradiating
a specimen with the illumination light from said light source;
objective lens switching means for selectively inserting a
plurality of objective lenses including a low-magnification
objective lens on an optical axis of observation light from the
specimen and positioning said plurality of objective lenses; and an
observation optical system for observing the specimen through one
of said plurality of objective lenses, wherein an effective
diameter of said observation optical system in observing the
specimen through said low-magnification objective lens is larger
than that of said illumination optical system.
2. An optical microscope according to claim 1, wherein said
low-magnification objective lens is a large-diameter objective lens
having a pupil diameter corresponding to the effective diameter of
said illumination optical system.
3. An optical microscope according to claim 1, wherein said
plurality of objective lenses includes an ordinary lens having a
pupil diameter corresponding to the effective diameter of said
illumination optical system.
4. An optical microscope according to claim 1, wherein mount lens
diameters of said plurality of objective lenses in said objective
lens switching means are different.
5. An optical microscope according to claim 1, wherein a height of
a mount surface of each objective lens can be adjusted so as to
maintain parfocal states in accordance with parfocal distances of
said objective lenses.
6. An optical microscope according to claim 1, further comprising a
mirror unit having an excitation filter, a dichroic mirror, and an
absorbing filter, all of which are commonly inserted in said
illumination optical system and said observation optical system,
said excitation filter having a size matching the effective
diameter of said illumination optical system, said dichroic mirror
and said absorbing filter having a size matching the effective
diameter of said observation optical system.
7. An optical microscope according to claim 1, wherein mount screw
diameters of said plurality of objective lenses in said objective
lens switching means are equal to each other, and said objective
lens switching means can adjust a height of a mount surface of each
objective lens so that the parfocal states are maintained in
accordance with parfocal distances of said objective lenses.
8. An optical microscope according to claim 1, wherein said
low-magnification objective lens has a magnification of not more
than 5.times..
9. An optical microscope according to claim 1, wherein the specimen
is a fluorescent specimen which generates fluorescence.
10. An optical microscope comprising: objective lens switching
means for selectively inserting a plurality of objective lenses
including a first objective lens on an observation optical axis for
a specimen and positioning said plurality of objective lenses; and
cube switching means for selectively and detachably positioning a
plurality of cubes on the observation optical axis, said plurality
of cubes including a cube having a mirror unit corresponding to
each microscopic method and a cube having a second objective lens
serving as an auxiliary lens used with said first objective
lens.
11. An optical microscope according to claim 10, wherein said first
objective lens is a very-low-magnification objective lens.
12. An optical microscope according to claim 10, wherein said cube
switching means is interlocked with the switching operation of said
objective lens switching means.
13. An optical microscope according to claim 10, wherein when said
first objective lens is positioned on the observation optical axis,
said second objective lens is positioned on the observation optical
axis.
14. An optical microscope according to claim 10, further
comprising: an objective lens position detection sensor for
detecting positions of said plurality of objective lenses; a cube
position detection sensor for detecting positions of said plurality
of cubes; and a processor for controlling an interlocking operation
between said objective lens switching means and said cube switching
means by referring to the detected positions of said objective
lenses and cubes.
15. An optical microscope according to claim 10, wherein said
second objective lens is detachable from said cube switching
means.
16. An optical microscope according to claim 10, wherein said cube
switching means has a turret for detachably fixing said plurality
of cubes.
17. An optical microscope according to claim 16, wherein said
second objective lens is detachably mounted in said turret.
18. An optical microscope according to claim 10, wherein said
second objective lens is integrally arranged with said cubes
together with a polarizer for selectively transmitting illumination
light from a light source, a beam splitter for reflecting light
transmitted through said polarizer toward a sample surface and
transmitting observation light from the sample surface, and an
analyzer for selectively transmitting the light transmitted through
said beam splitter.
19. An optical microscope according to claim 10, wherein said cube
having the mirror unit is a cube for fluorescence observation.
20. An optical micrscope according to claim 10, wherein said cube
having the mirror unit is a cube for polarized light
observation.
21. An optical microscope according to claim 10, wherein said cube
having the mirror unit is a cube for bright field observation.
22. An optical microscope according to claim 10, wherein said cube
having the mirror unit is a cube for dark field observation.
23. An optical microscope according to claim 10, wherein said
second objective lens serving as the auxiliary lens and said mirror
unit can be simultaneously inserted on the observation optical
axis.
24. An optical microscope according to claim 10, further comprising
a light source for emitting reflected light, wherein said second
objective lens serving as the auxiliary lens is arranged in a
specimen side with respect to an optical axis of the reflected
light emitted by said light source.
25. An optical microscope according to claim 10, further comprising
a light source for emitting reflected light, wherein said second
objective lens serving as the auxiliary lens is arranged in an
observation image obtaining side with respect to an optical axis of
the reflected light emitted by said light source.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an optical microscope
having an objective lens interchanging mechanism.
[0002] When observing a specimen such as a vital cell, observation
is performed while manipulating the specimen with a manipulator and
measuring the potential with an electrode. In this case, the entire
portion of the specimen is observed with a low-magnification
objective lens to determine the portion to be observed. Thereafter,
the low-magnification lens is switched to a high-magnification
lens, and observation is performed in detail.
[0003] Conventionally, an optical microscope having an objective
lens interchanging mechanism is proposed in order to use, by
switching, objective lenses having different magnifications in this
manner. For example, optical microscopes disclosed in Jpn. UM
Appln. KOKAI Publication No. 6-40910 and No. 6-4720 and Jpn. Pat.
Appln. KOKAI Publication No. 8-338940 are known. In each of these
optical microscopes, a plurality of objective lenses having the
same mount screw diameter that complies with the international
standards (parfocal distance: 45 mm; mount screw diameter W: 20.32;
and thread height: 36) and different magnifications are mounted to
the support. An objective lens having an optimum magnification can
be inserted on the observation optical axis in accordance with a
change in observation magnification.
[0004] When the objective lenses are to be used in fluorescence
observation by switching their magnification in this manner, as a
low-magnification objective lens for observing the entire portion
of the specimen, one having a magnification as low as possible is
usually preferable. Conventionally, the lower limit of the
magnification that can be employed is about 10.times.. This is
because the lower the magnification, the darker the observation
image. To observe a fluorescent image which is originally dark, the
magnification must be at least about 10.times.. If not, observation
becomes impossible.
[0005] To allow fluorescence observation at a low magnification,
the observation image must be made bright. The fluorescent
intensity may be increased by increasing the intensity of
excitation light. If the intensity of the excitation light is
excessively increased, the specimen may be damaged or discolored
with fluorescence, causing a trouble in observation.
[0006] To eliminate this, as a low-magnification objective lens,
for example, one having a magnification lower than 10.times. and
capable of ensuring a sufficiently high brightness for the
observation image may be used. According to the optical microscope
having the objective lens interchanging mechanism described above,
the objective lenses to be mounted to the support must comply with
the same standards and have the same mount screw diameter. If the
objective lenses have different mount screw diameters, they cannot
be mounted to the objective lens interchanging mechanism
simultaneously and cannot be interchangeably used. If the objective
lenses have different parfocal distances, when they are replaced,
the focal point is largely displaced from the specimen surface due
to the parfocal difference, and focusing must be performed again,
leading to inconveniences in use.
[0007] For this reason, an optical microscope which can stably
perform fluorescence observation with a low-magnification objective
lens is sought for. Particularly, the following requirements are
desired. A conventional illumination optical system must be used to
suppress an increase in manufacturing cost, the compactness of the
microscope must be maintained, and the microscope must be excellent
in operability.
[0008] The objective lens switching operation described above poses
the following problems.
[0009] Generally, in a microscope, a plurality of objective lenses
are detachably held by an objective lens revolver which performs a
switching operation among the plurality of objective lenses such
that they can be inserted in and removed from the observation
optical axis. Observation at a desired magnification is performed
by turning the objective lens revolver to switch the objective lens
on the observation optical axis.
[0010] In a microscope, since the height of eye point (the distance
from the desktop surface to the operator's eye) with which the
operator can perform observation with a natural posture is
substantially fixed, the sizes of the respective portions of the
microscope are limited. For example, the distance from the mounting
surface of the objective lens, with which the objective lens is to
be mounted to the objective lens revolver, to the sample surface
(this distance will be referred to as the parfocal distance
hereinafter) is usually designed to be about 45 mm. In an objective
lens having a very low magnification of 1.times. or less, its
parfocal distance is as very long as about 200 mm. If such an
objective lens is used, its entire length cannot be accommodated
within the parfocal distance. Therefore, it is impossible to change
the observation magnification by only turning the objective lens
revolver to switch the objective lens.
[0011] In order to solve this problem, conventionally, a microscope
disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-54253 is
known. According to this reference, one of a plurality of first
objective lenses is defined as a very-low-magnification objective
lens. The second objective lens fixed in an optical path is
arranged with respect to a revolver means that performs a switching
operation among the plurality of first objective lenses so that the
selected one is located in the optical path. An observation image
of an object is formed through the first objective lens selected by
the revolver means and the second objective lens. A
very-low-magnification auxiliary lens, which is to be inserted in
an interlocked manner with selection of the very-low-magnification
objective lens done by the revolver means, is arranged in the
optical path between the first and second objective lenses. The
first very-low-magnification objective lens is constituted by the
very-low-magnification auxiliary lens and the
very-low-magnification objective lens. More specifically, the
very-low-magnification objective lens, the entire length of which
cannot be accommodated within the parfocal distance, is divided
into two portions, i.e., the first objective lens mounted to the
revolver means, and the very-low-magnification auxiliary lens, and
is constituted such that its synthetic focal distance becomes about
200 mm. The observation magnification, including the very low
magnification, can be changed by inserting and removing the
very-low-magnification auxiliary lens in and from the optical path
in an interlocked manner with selection of the
very-low-magnification objective lens by the revolver means.
[0012] In the microscopes disclosed in the above references, merely
the very-low-magnification auxiliary lens is arranged in the
optical path between the first and second objective lenses, and no
description is made concerning the practical arrangement of the
very-low-magnification auxiliary lens. For this reason,
[0013] (1) For example, when an extra space is newly prepared
exclusively for the very-low-magnification auxiliary lens, not only
the eye point described above becomes high, but also the entire
microscope becomes large.
[0014] (2) The switching mechanism for inserting and removing the
very-low-magnification auxiliary lens in and from the optical path
must be prepared exclusively for the very-low-magnification
objective lens, and must be interlocked with the turning operation
of the revolver means. This leads to a complicated arrangement and
an increase in cost, which is not preferable.
[0015] (3) Although the observation magnification can be changed,
the microscopic method must be switched by separately providing a
switching mechanism, resulting in a degradation in operability.
[0016] Generally, a very-low-magnification objective lens has a
long focal distance and a large radius of lens curvature.
Particularly, when performing observation with reflected light,
noise such as flare, ghost, or the like which affects original
image formation tends to be caused by repeated surface reflection
of the lens. In order to solve this, in general, a polarizer is
inserted in the reflected light optical system, an analyzer is
inserted, in an observation optical-system, behind (image side) an
objective lens and behind (image side) a half mirror that coaxially
introduces the reflected light optical axis into the observation
optical axis, and a .lambda./4 plate and a depolarizer are inserted
in the distal end (closest to the sample) of the objective lens.
When a high-magnification objective lens is employed, the influence
of the flare or ghost is small. In this case, the polarizer, the
analyzer, the .lambda./4 plate, and the depolarizer need not be
used or are better be omitted as they decrease brightness. If the
.lambda./4 plate and the depolarizer are mounted to the distal end
of the very-low-magnification objective lens mounted to the
revolver means, they can be inserted or removed upon the turning
operation of the revolver means, thus solving the problem.
[0017] (4) Even with this arrangement, since the polarizer and
analyzer are left inserted in the optical path, a mechanism is
necessary which inserts them in the optical path for
very-low-magnification observation and removes them from the
optical path for other observation. This leads to a cumbersome
operation and complicated arrangement, leading to an increase in
cost.
[0018] Jpn. Pat. Appln. KOKAI Publication No. 6-109962 discloses a
prior art in which an objective lens revolver is turned
electrically. To turn the revolver electrically itself is a known
technique, and the revolver is not interlocked with a movable
portion which is necessary for other microscopic method switching
and the like. As disclosed in Jpn. Pat. Appln. KOKAI Publication
No. 7-311342 and No. 63-133115, a technique is known which improves
the operability by interlocking insertion/removal of optical
elements and the like, required for performing a switching
operation among various types of microscopic methods, light
control, a stop, a cube, and the like. However, no description is
made concerning two types of objective lenses which are inserted in
and removed from the optical path in an interlocked manner during
magnification switching. Also, no description is made concerning an
objective lens for magnification switching, which is inserted in
and removed from the optical path with the same drive member as
that employed for microscopic method switching. Hence, problems
similar to those of Jpn. Pat. Appln. KOKAI Publication No. 9-54253
exist.
[0019] From the above reasons, an optical microscope which solves
the various problems described above is sought for.
BRIEF SUMMARY OF THE INVENTION
[0020] Accordingly, it is an object of the present invention to
provide a compact, high-operability optical microscope.
[0021] It is another object of the present invention to provide an
optical microscope which can stably perform fluorescence
observation with a low-magnification objective lens.
[0022] According to a first aspect of the present invention, there
is provided an optical microscope comprising: a light source for
emitting illumination light; an illumination optical system for
irradiating a specimen with the illumination light from the light
source; objective lens switching means for selectively inserting a
plurality of objective lenses including a low-magnification
objective lens on an optical axis of observation light from the
specimen and positioning the plurality of objective lenses; and an
observation optical system for observing the specimen through one
of the plurality of objective lenses, wherein an effective diameter
of the observation optical system in observing the specimen through
the low-magnification objective lens is larger than that of the
illumination optical system.
[0023] With the above arrangement, the brightness of the
observation image of the fluorescent specimen can be increased, and
fluorescence observation is allowed at a lower magnification. The
effective diameter of the illumination optical system need not be
increased and can be equal to that of the conventional case. The
intensity of excitation light does not change to prevent damage to
the specimen and its discoloration. In addition, any conventional
illumination optical system can be used without any modification,
resulting in an advantage in the manufacture. The size of only the
observation optical system is increased, thereby contributing to
downsizing of the microscope.
[0024] In the optical microscope, the low-magnification objective
lens may be a large-diameter objective lens having a pupil diameter
corresponding to the effective diameter of the illumination optical
system.
[0025] In the optical microscope, the plurality of objective lenses
may include an ordinary objective lens having a pupil diameter
corresponding to the effective diameter of the illumination optical
system.
[0026] In the optical microscope, the mount lens diameters of the
plurality of objective lenses in the objective lens switching means
may be different.
[0027] In the optical microscope, the height of the mount surface
of each objective lens can be adjusted so as to maintain parfocal
states in accordance with the parfocal distances of the objective
lenses.
[0028] The optical microscope further comprises a mirror unit
having an excitation filter, a dichroic mirror, and an absorbing
filter, all of which are commonly inserted in the illumination
optical system and the observation optical system. The excitation
filter may have a size matching the effective diameter of the
illumination optical system. The dichroic mirror and the absorbing
filter may have a size matching the effective diameter of the
observation optical system.
[0029] In the optical microscope, the mount screw diameters of the
plurality of objective lenses in the objective lens switching means
are equal to each other. The objective lens switching means can
adjust the height of the mount surface of each objective lens so
that the parfocal states are maintained in accordance with the
parfocal distances of the objective lenses.
[0030] In the optical microscope, the low-magnification objective
lens preferably has a magnification of 5.times. or less.
[0031] In the optical microscope, the specimen is preferably a
fluorescent specimen which generates fluorescence.
[0032] According to a second aspect of the present invention, there
is provided an optical microscope comprising: objective lens
switching means for selectively inserting a plurality of objective
lenses including a first objective lens on an observation optical
axis for a specimen and positioning the plurality of objective
lenses; and cube switching means for selectively and detachably
positioning a plurality of cubes on the observation optical axis,
the plurality of cubes including a cube having a mirror unit
corresponding to each microscopic method and a cube having a second
objective lens serving as an auxiliary lens used with the first
objective lens.
[0033] With the above arrangement, an exclusive space for the
second objective lens need not be formed to achieve space saving,
thereby providing a compact microscope.
[0034] In the optical microscope, the first objective lens is
preferably a very-low-magnification objective lens.
[0035] In the optical microscope, the cube switching means is
preferably interlocked with the switching operation of the
objective lens switching means. More specifically, when the first
objective lens is positioned on the observation optical axis, the
second objective lens is preferably positioned on the observation
optical axis.
[0036] The optical microscope may further comprise an objective
lens position detection sensor for detecting positions of the
plurality of objective lenses, a cube position detection sensor for
detecting positions of the plurality of cubes, and a processor for
controlling an interlocking operation between the objective lens
switching means and the cube switching means by referring to the
detected positions of the objective lenses and cubes.
[0037] In the optical microscope, the second objective lens may be
detachable from the cube switching means.
[0038] In the optical microscope, the cube switching means may have
a turret for detachably fixing the plurality of cubes. In this
case, the second objective lens may be detachably mounted in the
turret.
[0039] In the optical microscope, the second objective lens may be
integrally arranged with the cubes together with a polarizer for
selectively transmitting illumination light from a light source, a
beam splitter for reflecting light transmitted through the
polarizer toward a sample surface and transmitting observation
light from the sample surface, and an analyzer for selectively
transmitting the light transmitted through the beam splitter.
[0040] In the optical microscope, the cube having the mirror unit
may be a cube for fluorescence observation.
[0041] In the optical microscope, the cube having the mirror unit
may be a cube for polarized light observation.
[0042] In the optical microscope, the cube having the mirror unit
is a cube for bright field observation.
[0043] In the optical microscope, the cube having the mirror unit
is a cube for dark field observation.
[0044] In the optical microscope, the second objective lens serving
as the auxiliary lens and the mirror unit can be simultaneously
inserted on the observation optical axis.
[0045] The optical microscope may further comprise a light source
for emitting reflected light. In this case, the second objective
lens serving as the auxiliary lens may be arranged in a specimen
side with respect to an optical axis of the reflected light emitted
by the light source.
[0046] The optical microscope may further comprise a light source
for emitting reflected light. In this case, the second objective
lens serving as the auxiliary lens may be arranged in an
observation image obtaining side with respect to an optical axis of
the reflected light emitted by the light source.
[0047] Additional objects and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinbefore.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0048] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate presently
preferred embodiments of the invention, and together with the
general description given above and the detailed description of the
preferred embodiments given below, serve to explain the principles
of the invention.
[0049] FIG. 1 is a view showing the schematic arrangement of a
reflected light fluorescence microscope applied to the first
embodiment of the present invention;
[0050] FIG. 2 is a view schematically showing the optical path of
the reflected light fluorescence microscope applied to the first
embodiment;
[0051] FIG. 3 is a view showing the schematic arrangement of the
objective lens interchanging mechanism of the reflected light
fluorescence microscope applied to the first embodiment;
[0052] FIG. 4 is a view showing the schematic arrangement of the
objective lens interchanging mechanism of the reflected light
fluorescence microscope applied to the first embodiment;
[0053] FIG. 5 is a view showing the schematic arrangement of the
turret of the reflected light fluorescence microscope applied to
the first embodiment;
[0054] FIG. 6 is a view showing the schematic arrangement of the
mirror unit of the turret of the reflected light fluorescence
microscope applied to the first embodiment;
[0055] FIG. 7 is a view showing the schematic arrangement of the
mirror unit of the turret of the reflected light fluorescence
microscope applied to the first embodiment;
[0056] FIG. 8 is a view showing the schematic arrangement of the
objective lens interchanging mechanism of a reflected light
fluorescence microscope applied to the second embodiment of the
present invention;
[0057] FIG. 9 is a view showing the schematic arrangement of the
objective lens interchanging mechanism of a reflected light
fluorescence microscope applied to the third embodiment of the
present invention;
[0058] FIG. 10 is a view showing the schematic arrangement of the
objective lens interchanging mechanism of the reflected light
fluorescence microscope applied to the third embodiment;
[0059] FIGS. 11A and 11B are views showing the schematic
arrangement of the objective lens interchanging mechanism of a
reflected light fluorescence microscope applied to the fourth
embodiment of the present invention;
[0060] FIG. 12 is a view showing the entire portion of an optical
microscope applied to the fifth embodiment of the present
invention;
[0061] FIG. 13 is a view showing the schematic arrangement of the
fifth embodiment;
[0062] FIG. 14 is a view showing the schematic arrangement of a
revolver used in the fifth embodiment;
[0063] FIGS. 15A and 15B are views showing the schematic
arrangement of a turret used in the fifth embodiment;
[0064] FIG. 16 is a view showing the schematic arrangement of a
control system applied to the fifth embodiment;
[0065] FIGS. 17A to 17C are views showing the schematic
arrangements of various types of cubes applied to the fifth
embodiment;
[0066] FIG. 18 is a view showing the schematic arrangement of the
sixth embodiment of the present invention; and
[0067] FIG. 19 is a view showing the schematic arrangement of the
seventh embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0068] The preferred embodiments of the present invention will be
described with reference to the accompanying drawing.
[0069] [First Embodiment]
[0070] FIG. 1 shows the schematic arrangement of a reflected light
fluorescence microscope applied to the first embodiment of the
present invention. Referring to FIG. 1, reference numeral 1 denotes
a microscope main body. The microscope main body 1 has an arm 102
projecting parallel to a base 101.
[0071] A stage 3 where a specimen 2 is placed is formed on the base
101 of the microscope main body 1. While the specimen 2 is placed
on it, the stage 3 can be moved in an X-Y direction within a plane
perpendicular to the observation optical axis.
[0072] A focusing unit 103 supports an objective lens interchanging
mechanism 4. The objective lens interchanging mechanism 4 can be
vertically moved along the observation optical axis by rotating a
knob 5 provided to the base 101 of the microscope main body 1.
[0073] Objective lenses 21 and 22 are mounted to the objective lens
interchanging mechanism 4. The objective lenses 21 and 22 can be
selectively inserted in and positioned on the observation optical
axis for the specimen 2 on the stage 3.
[0074] In this case, the objective lens 21 is a low-magnification
(about 5.times. or less), large-diameter lens having a large exit
pupil, and the objective lens 22 is an ordinary lens which complies
with the international standards. An ordinary lens with a
magnification of 4.times. has a parfocal distance of 45 mm, a mount
screw diameter W of 20.32, a thread of 36, and NA=0.16, while a
large-diameter lens with a magnification of 4.times. has a parfocal
distance of 60 mm, a mount screw diameter M of 35.times.1, and
NA=0.28. An ordinary lens with a magnification of 2.times. has a
parfocal distance of 45 mm, a mount screw diameter W of 20.32, a
thread of 36, and NA=0.98, while a large-diameter lens with a
magnification of 2.times. has a parfocal distance of 60 mm, a mount
screw diameter M of 35.times.1, and NA=0.14. The calculation values
indicate that in each of the 4.times. and 2.times. lenses, a lens
having a larger diameter than that of an ordinary lens has a
brightness 3 times that of the ordinary lens (the brightness is
proportional to 20% NA). Concerning the large-diameter objective
lens 21, its parfocal distance and mount screw diameter may be
changed and the NA value may be set such that the brightness
becomes 2 to 4 times.
[0075] A turret 16 having a lamp housing 23, a light projection
tube 9, and a mirror unit 10 is arranged on the arm 102. The lamp
housing 23 emits illumination light serving as the illumination
source. The light projection tube 9 guides the illumination light
from the lamp housing 23 and has at least one lens (not shown) for
optimizing the illumination light. The mirror unit 10 has an
excitation filter 11, a dichroic mirror 12, and an absorbing filter
13. The excitation filter 11 selects only a light component in a
necessary wavelength range of the illumination light. The dichroic
mirror 12 bends the optical path. The absorbing filter 13 removes a
disturbing light beam from fluorescence generated by the
specimen.
[0076] A lens barrel 14 and an eyepiece 15 are arranged above the
mirror unit 10.
[0077] FIG. 2 shows the schematic diagram of the optical path of
the reflected light fluorescence microscope having this
arrangement. Illumination light 231 emitted from the lamp housing
23 passes through an optical system 901 of the light projection
tube 9, is reflected by the dichroic mirror 12 through the
excitation filter 11, passes through the objective lens 21 (22)
which is inserted in and positioned on the observation optical axis
by the objective lens interchanging mechanism 4, and irradiates the
specimen 2 on the stage 3. Observation fluorescence generated by
the specimen 2 passes through the objective lens 21 (22) again and
the absorbing filter 13 to get rid of the disturbing light beam
through the absorbing filter 13, and is converted by a tube lens 17
to be observed through the lens barrel 14 and eyepiece 15.
[0078] Accordingly, while the low-magnification objective lens 21
having a large exit pupil is inserted in and positioned on the
observation optical axis, an effective diameter a of the
observation optical system which is generated by the specimen 2 and
obtained through the objective lens 21 is larger than an effective
diameter b of the illumination optical system constituted by the
illumination light 231.
[0079] FIGS. 3 and 4 show the schematic arrangement of the
objective lens interchanging mechanism 4 applied to such a
reflected light fluorescence microscope.
[0080] Referring to FIGS. 3 and 4, reference numeral 401 denotes
the stationary portion of the objective lens interchanging
mechanism 4. A dovetail 402 is formed on the upper surface of the
stationary portion 401. The stationary portion 401 can be mounted
to and removed from the arm 102 described above through the
dovetail 402. The stationary portion 401 has a dovetail groove 403
in its lower surface. A movable portion 404 is arranged to be
linearly movable along the dovetail groove 403 in the direction of
a double-headed arrow shown in FIG. 4.
[0081] The movable portion 404 has lens mount portions 405 for the
two objective lenses 21 and 22, respectively. When the movable
portion 404 is linearly moved, the lens mount portions 405 and 406
can be selectively set to coincide with an opening 4011 on the
observation optical axis of the stationary portion 401. In this
case, a stopper 4012 is arranged in the stationary portion 401.
When the lens mount portion 405 or 406 of the movable portion 404
is located on the observation optical axis, a side surface 4051 or
4061 of the lens mount portion 405 or 406 abuts against the stopper
4012. FIG. 4 shows a state wherein the side surface 4051 of the
lens mount portion 405 abuts against the stopper 4012.
[0082] The objective lenses 21 and 22 having different screw
diameters and different parfocal distances can be mounted to the
lens mount portions 405 and 406, respectively, of the movable
portion 404. Of the lens mount portions 405 and 406, the lens mount
portion 405 has a mount screw portion 4052 with such a mount screw
diameter that the objective lens 21, the mount screw diameter of
which is increased to set a large NA and the parfocal distance of
which is increased in order to increase the working distance, can
be mounted to it as the low-magnification large-diameter objective
lens having a large exit pupil. The lens mount portion 406 has a
mount screw portion 4062 with a mount screw diameter that complies
with the international standards, so that the ordinary objective
lens 22 can be mounted to it. Furthermore, the lens mount portions
405 and 406 respectively have objective lens mounting surfaces 4053
and 4063 having a step difference corresponding to the parfocal
difference between the objective lenses 21 and 22. Even when a
switching operation is performed between the objective lenses 21
and 22 having different parfocal distances, the parfocal state is
maintained.
[0083] FIGS. 5 to 7 show the schematic arrangement of the turret 16
having the mirror unit 10.
[0084] In this case, the turret 16 shown in FIG. 5 can be
detachably mounted to the light projection tube 9 described above
through a mount portion 1601. The turret 16 has a rotatable body
1602, and has a vertical shaft 1603 at the center of the rotatable
body 1602. The rotatable body 1602 has a plurality of openings
1604. Dovetails 1605 on which a plurality of mirror units 10 are to
be mounted are formed around the vertical shaft 1603.
[0085] Each mirror unit 10 has the excitation filter 11, the
dichroic mirror 12, and the absorbing filter 13, as shown in FIG.
6, and has a dovetail groove 1001 in its side surface, as shown in
FIG. 7. When the dovetail groove 1001 is fitted with a
corresponding one of the dovetails 1605 of the vertical shaft 1603,
the plurality of mirror units 10 are mounted on the rotatable body
1602 of the turret 16. In this state, when the vertical shaft 1603
is rotated together with the rotatable body 1602, a desired mirror
unit 10 can be located on the observation optical axis.
[0086] In the mirror unit 10 shown in FIG. 6, the diameter of the
excitation filter 11 located in the illumination optical axis
having the effective diameter b, and the diameters of the dichroic
mirror 12 and absorbing filter 13 located in the observation
optical axis having the effective diameter a are different from
each other.
[0087] The operation of the embodiment having the above arrangement
will be described.
[0088] In this case, the objective lenses 21 and 22 are fixed by
respectively screwing them in and causing them to abut against the
mount screw portions 4052 and 4062 of the lens mount portions 405
and 406 of the movable portion 404, and the movable portion 404 is
mounted on the focusing unit 103 of the microscope main body 1
through the dovetail 402. The rotatable body 1602 of the turret 16
is rotated to locate the desired mirror unit 10 on the observation
optical axis.
[0089] In this state, the movable portion 404 is linearly moved.
The side surface 4051 of the lens mount portion 405 of the
objective lens 21 is abutted against the stopper 4012 to position
the low-magnification objective lens 21 having a large exit pupil
on the observation optical axis.
[0090] The illumination source of the lamp housing 23 is turned on.
The knob 5 is operated to vertically move the objective lens
interchanging mechanism 4 along the observation optical axis,
thereby adjusting the focal point of the objective lens 21 to
coincide with the specimen 2. In this state, the illumination light
231 from the lamp housing 23 passes through the optical system 901,
and is reflected by the dichroic mirror 12 through the excitation
filter 11, to irradiate the specimen 2 through the objective lens
21. Observation fluorescence generated by the specimen 2 passes
through the objective lens 21 again and the absorbing filter 13,
and serves for reflected light fluorescence observation through the
lens barrel 14 and eyepiece 15.
[0091] The movable portion 404 is linearly moved in the direction
opposite to that described above to cause the side surface 4061 of
the lens mount portion 406 of the objective lens 22 to abut against
the stopper 4012, so that the ordinary objective lens 22 is
positioned on the observation optical axis. At this time, reflected
light fluorescence observation through the objective lens 22 is to
be performed. When the microscopic method is to be changed, the
rotatable body 1602 of the turret 16 may be operated to locate a
desired mirror unit 10 on the observation optical axis.
[0092] In this manner, the illumination light 231 emitted from the
lamp housing 23 irradiates the specimen 2 on the stage 3 through
the illumination optical system having the light projection tube 9
and excitation filter 11. Observation fluorescence generated by the
specimen 2 is converted to be observed through the observation
optical system having the objective lenses 21 and 22, which are
selectively inserted in and positioned on the observation optical
system by the objective lens interchanging mechanism 4, the
dichroic mirror 12, and the absorbing filter 13. The effective
diameter a of the observation optical system, which is obtained
when the low-magnification objective lens 21 having a large exit
pupil is inserted in and positioned on the observation optical
axis, is set to be larger than the effective diameter b of the
illumination optical system. Since the effective diameter a of the
observation optical system is set large, the brightness of the
observation image of the fluorescent specimen 2 can be increased,
and fluorescence observation at a low magnification is allowed.
Regarding the illumination optical system, the effective diameter
is not increased but is left at the same value as in the
conventional case. Since the intensity of the excitation light is
not changed accordingly, damage, or degradation in discoloration,
of the specimen can be prevented. The light projection tube 9 and
excitation filter 11 of the conventional illumination optical
system can be used unchanged, which is advantageous in the
manufacture. Only the size of the observation optical system need
be increased, contributing to downsizing of the microscope.
[0093] The ordinary objective lens 22 having a pupil corresponding
to the effective diameter b of the illumination optical system, and
the large-diameter objective lens 21 having a pupil corresponding
to the effective diameter a of the observation optical system, may
be mounted to the same objective lens interchanging mechanism 4,
and can be selectively used.
[0094] In the objective lens interchanging mechanism 4, the
objective lens mounting surfaces 4053 and 4063 are respectively set
such that the objective lenses 21 and 22 can be detachably mounted
in the mount screw portions 4052 and 4062 having different mount
screw diameters and that the parfocal states of the objective
lenses 21 and 22 are maintained in accordance with the parfocal
distances of the objective lenses 21 and 22. Even when the
large-diameter objective lens 21 has a parfocal distance different
from that of the ordinary objective lens 22 for optimal design, the
objective lenses 21 and 22 can be mounted to the same objective
lens interchanging mechanism 4 and a switching operation can be
performed between them while their parfocal states are maintained,
thus eliminating focusing upon the switching operation.
[0095] The mirror units 10 prepared to match all the
interchangeable objective lenses 21 and 22 need not be introduced
from the outside upon switching the objective lens, thereby
simplifying replacement of the mirror unit 10. The switching
operation between the objective lenses 21 and 22 is a slide
operation in the back-and-forth direction when seen from the
operator. Hence, a large left-to-right space can be ensured for the
objective lens. Also, an objective lens vertical moving method that
vertically moves the objective lens interchanging mechanism 4 is
employed in the microscope main body 1. Since the position of the
specimen 2 is fixed, this arrangement is optimum for an application
such as a manipulator.
[0096] The microscope main body 1 is formed into a U-letter shape
in which the arm 102 projects parallel to the base 101. Therefore,
the microscope main body 1 has a high rigidity and can be easily
combined with a system such as a TV camera.
[0097] In the embodiment described above, the present invention is
applied to a reflected light fluorescence microscope. The present
invention can also be applied to a microscope other than this. In
the above description, the heights of the barrel mount surfaces of
the objective lenses are set such that a difference between the
parfocal distances of the objective lenses 21 and 22 mounted to the
objective lens interchanging mechanism 4 is canceled, and a
switching operation is performed between the objective lenses 21
and 22 having different parfocal distances while the parfocal
states are maintained. In this case, the mount screw diameters of
the objective lenses 21 and 22 may be the same, while only their
parfocal distances may be different. The parfocal distance of the
objective lens 21 may be set to be equal to that of the objective
lens 22, while only their mount screw diameter may be changed in
accordance with the necessary luminous flux diameter. In the above
description, in order to set the condition optimum for using a
manipulator, the stage 3 is fixed, while the objective lenses 21
and 22 are vertically moved along the observation optical axis.
However, the stage 3 side may be vertically moved along the
observation optical axis. Furthermore, the mount screw portion 4052
of the lens mount portion 405 formed on the movable portion 404 is
set to match the large-diameter objective lens 21. When an ordinary
objective lens is to be used, an adapter may be mounted by using
the mount screw portion 4052.
[0098] [Second Embodiment]
[0099] FIG. 8 shows the schematic arrangement of an objective lens
interchanging mechanism 4 applied to the second embodiment of the
present invention.
[0100] Referring to FIG. 8, reference numeral 410 denotes the
stationary portion of the objective lens interchanging mechanism 4.
A dovetail 411 is formed on the upper surface of the stationary
portion 410. The objective lens interchanging mechanism 4 can be
detachably mounted on a focusing unit 103 identical to that
described above through the dovetail 411.
[0101] The stationary portion 410 is provided with a pivotal
portion 413 which is pivotal about a shaft 412 as the center in the
directions of a double-headed arrow in FIG. 8. The pivotal portion
413 has lens mount portions 414 and 415 for two objective lenses 21
and 22. When the pivotal portion 413 is pivoted, the lens mount
portions 414 and 415 can be selectively set to coincide with the
observation optical axis of the stationary portion 410. In this
case, stoppers 4101 and 4102 are formed on the stationary portion
410. When the lens mount portion 414 or 415 is located on the
observation optical axis, the side surface of the pivotal portion
413 abuts against the stopper 4101 or 4102. In FIG. 8, the side
surface of the pivotal portion 413 abuts against the stopper
4101.
[0102] The objective lenses 21 and 22 having different screw
diameters and different parfocal distances can be mounted to the
lens mount portions 414 and 415, respectively, of the pivotal
portion 413. Of the lens mount portions 414 and 415, the lens mount
portion 414 has a mount screw portion 4141 with such a mount screw
diameter that the objective lens 21, the mount screw diameter of
which is increased to set a large NA and the parfocal distance of
which is increased in order to increase the working distance, can
be mounted to it as the low-magnification large-diameter objective
lens having a large exit pupil. The lens mount portion 415 has a
mount screw portion 4151 with a mount screw diameter that complies
with the international standards, so that the ordinary objective
lens 22 can be mounted to it. Furthermore, the lens mount portions
414 and 415 respectively have objective lens mounting surfaces 4142
and 4152 having a step difference corresponding to the parfocal
difference between the objective lenses 21 and 22. Even when a
switching operation is performed between the objective lenses 21
and 22 having different parfocal distances, the parfocal state is
maintained.
[0103] The same effect as that of the first embodiment described
above can be expected. Since a switching operation between the
objective lenses 21 and 22 can be performed by only pivoting the
pivotal portion 413, the arrangement of the objective lens
interchanging mechanism 4 can be further simplified, and a stable
switching operation can be obtained.
[0104] The mount screw portion 4141 of the lens mount portion 414
formed on the pivotal portion 413 is set to match the
large-diameter objective lens 21. When an ordinary objective lens
is to be used, an adapter may be mounted by using the mount screw
portion 4141.
[0105] [Third Embodiment]
[0106] FIGS. 9 and 10 show the schematic arrangement of an
objective lens interchanging mechanism 4 applied to the third
embodiment of the present invention. Portions that are identical to
those of FIGS. 3 and 4 are denoted by the same reference numerals
as in FIGS. 3 and 4.
[0107] In this case, a lens mount portion 406 of a movable portion
404 which serves to mount an objective lens 22 has a parfocal
adjusting member 417. The parfocal adjusting member 417 is mounted
to a lens mount portion 406 through a screw portion 4171, and its
height with respect to the lens mount portion 406 can be adjusted
by the screwing amount of the screw portion 4171. The parfocal
adjusting member 417 has a mount screw portion 4172 for the
objective lens 22.
[0108] Except for these respects, the arrangements of FIGS. 9 and
10 are identical to those of FIGS. 3 and 4. Accordingly, the same
effect as that of the first embodiment described above can be
expected. Since the mounting surface position of the objective lens
22 can be adjusted in accordance with the parfocal distance of the
objective lens 22 to be used, one objective lens interchanging
mechanism 4 can cope with the objective lenses 22 having different
parfocal distances as far as they have the same mount screw
diameter. The mounting surface position of the objective lens 22
can be adjusted and corrected for variations in parfocal distances
of the respective objective lenses 22 and variations in distance
from the surface of the specimen 2 to the water surface, as in a
case where the specimen 2 is located in an aqueous solution.
Therefore, re-focusing is not required when the objective lens is
to be replaced, and the objective lens interchanging operation can
be performed easily.
[0109] In the third embodiment, the parfocal adjusting member 417
performs height adjustment with the screw portion 4171 in
accordance with the parfocal distance. Alternatively, such a screw
portion need not be used. In this case, members (adapters) matching
the parfocal distances of the respective objective lenses may be
prepared, and corresponding one may be mounted and used in
accordance with the objective lens to be employed.
[0110] [Fourth Embodiment]
[0111] FIGS. 11A and 11B show the schematic arrangement of an
objective lens interchanging mechanism 4 applied to the fourth
embodiment of the present invention.
[0112] Referring to FIGS. 11A and 11B, reference numeral 420
denotes the stationary portion of the objective lens interchanging
mechanism 4. A dovetail 421 is formed on the upper surface of the
stationary portion 420. The objective lens interchanging mechanism
4 can be detachably mounted on a focusing unit 103 identical to
that described with reference to FIG. 1 through the dovetail
421.
[0113] The stationary portion 420 is provided with a rotatable
portion 422 to be pivotal through a bearing 423 in the directions
of a double-headed arrow in FIG. 11A. The rotatable portion 422 has
lens mount portions 425 and 426 for at least two objective lenses
21 and 22. When the rotatable portion 422 is pivoted, the lens
mount portions 425 and 426 can be selectively set to coincide with
the observation optical axis of the stationary portion 420. In this
case, the stationary portion 420 has a click 424 to which a spring
force is applied. When one of the lens mount portions 425 and 426
is located on the observation optical axis, the click 424 of the
stationary portion 420 is fitted in a V-groove 4221 of the
rotatable portion 422, as shown in FIG. 11B. In FIG. 11A, the lens
mount portion 425 is located on the observation optical axis and
the click 424 of the stationary portion 420 is fitted in the
V-groove 4221.
[0114] The objective lenses 21 and 22 having different screw
diameters and different parfocal distances can be mounted to the
lens mount portions 425 and 426, respectively, of the rotatable
portion 422. Of the lens mount portions 425 and 426, the lens mount
portion 425 has a mount screw portion 4251 with such a mount screw
diameter that the objective lens 21, the mount screw diameter of
which is increased to set a large NA and the parfocal distance of
which is increased in order to increase the working distance, can
be mounted to it as the low-magnification large-diameter objective
lens having a large exit pupil. The lens mount portion 426 has a
mount screw portion 4261 with a mount screw diameter that complies
with the international standards, so that the ordinary objective
lens 22 can be mounted to it. Furthermore, the lens mount portions
425 and 426 respectively have objective lens mounting surfaces 4252
and 4262 having a step difference corresponding to the parfocal
difference between the objective lenses 21 and 22. Even when a
switching operation is performed between the objective lenses 21
and 22 having different parfocal distances, the parfocal state is
maintained.
[0115] Therefore, the same effect as that of the first embodiment
described above can be expected. Since a switching operation
between the objective lenses 21 and 22 can be performed by only
rotating the rotatable portion 422, the arrangement of the
objective lens interchanging mechanism 4 can be further simplified,
and a stable switching operation can be obtained.
[0116] The mount screw portion 4251 of the lens mount portion 425
formed on the rotatable portion 422 is set to match the
large-diameter objective lens 21. When an ordinary objective lens
is to be used, an adapter may be mounted by using the mount screw
portion 4251.
[0117] As described above through the first to fourth embodiments,
according to the first aspect of the present invention, when the
effective diameter of the observation optical axis is increased,
the brightness of the observation image of the fluorescent specimen
can be increased, and fluorescence observation at a lower
magnification is allowed. The effective diameter of the
illumination optical system is not increased but is left at the
same value as in the conventional case. Since the intensity of the
excitation light is not changed accordingly, damage, or degradation
in discoloration, of the specimen can be prevented. The
conventional illumination optical system (e.g., the light
projection tube and excitation filter) can be used unchanged, which
is advantageous in the manufacture. Only the size of the
observation optical system need be increased, contributing to
downsizing of the microscope.
[0118] The objective lens or a so-called ordinary lens having a
pupil corresponding to the effective diameter of the illumination
optical system, and an objective lens or a so-called large-diameter
objective lens having a pupil corresponding to the effective
diameter (which is set larger than the effective diameter of the
illumination optical system) of the observation optical system, may
be mounted to the same objective lens interchanging means, and can
be selectively used.
[0119] Even when the large-diameter objective lens has a parfocal
distance different from that of the ordinary objective lens for
optimal design, the objective lenses can be mounted to the same
objective lens interchanging means and a switching operation can be
performed between them while their parfocal states are maintained,
thus eliminating focusing upon the switching operation.
[0120] [Fifth Embodiment]
[0121] FIG. 12 is an overall view of a microscope to which the
present invention is applied. Referring to FIG. 12, reference
numeral 51 denotes a microscope main body. The microscope main body
51 has a base 601 and an arm 602 projecting parallel to the base
601. In the microscope main body 51, a stage 52 is arranged
parallel to the base 601 and arm 602. A sample (not shown) is
placed on the stage 52. The stage 52 is movable in an X-Y direction
within a plane perpendicular to an observation optical axis 53.
[0122] A reflected light optical system 56 having a reflected light
source 54 and a collector lens 55 is arranged on the arm 602 side
of the microscope main body 51. Reflected light generated by the
reflected light optical system 56 passes through a cube unit 7 and
an objective lens unit 8 to irradiate the sample on the stage 52
along the observation optical axis 53. An obtained fluorescent
image can be observed with an image sensing means (not shown),
e.g., an eyepiece or a TV camera, through the objective lens unit
8, the cube unit 7, and a tube lens 59. A transmitted light optical
system 63 having a transmitted light source 60, a collector lens
61, and a mirror 62 is arranged on the base 601 side. Reflected
light generated by the transmitted light optical system 63 passes
through a condenser lens 64 and is transmitted through the sample
on the stage 52 along the observation optical axis 53. An obtained
transmitted bright field observation image can be observed with an
image sensing means (not shown), e.g., an eyepiece or a TV camera,
through the objective lens unit 8, the cube unit 7, and the tube
lens 59.
[0123] As shown in FIG. 13, the objective lens unit 8 is
constituted by a revolver 81, one very-low-magnification objective
lens, e.g., a 0.5.times. objective lens 82, and a plurality of
objective lenses 83 (only one is shown in FIG. 13). The revolver 81
serves as an objective lens interchanging means. The 0.5.times.
objective lens 82 serves as the first objective lens held by the
revolver 81. The objective lenses 83 have an ordinary
magnification. In the revolver 81, a rotatable portion 813 is held,
through a ball 812, by a stationary portion 811 fixed to the arm
602 of the microscope main body 51, such that it is rotatable about
a rotation axis 814, which is inclined by a predetermined angle, as
the center. In this case, a through hole 8111 is formed in the
stationary portion 811 along the observation optical axis 53, and a
plurality of screw holes 8131 are formed in the rotatable portion
813 at the respective mount positions of the objective lenses 82
and 83 (see FIG. 14). Each screw hole 8131 can communicate with the
through hole 8111 of the stationary portion 811 on the observation
optical axis 53. The rotatable portion 813 has a gear portion 8132
on its outer circumferential edge. A gear 652 of a rotating shaft
651 of a motor 65 meshes with the gear portion 8132. The rotatable
portion 813 is rotated by the motor 65 about the rotation axis 814
as the center. In the rotatable portion 813, click grooves 815 are
equidistantly formed along the outer circumferential edge portion.
The rotatable portion 813 is also positioned when a ball 817 at the
distal end of a positioning click spring 816 arranged in the
stationary portion 811 is fitted in one of the click grooves
815.
[0124] In the 0.5.times. objective lens 82, lenses 822 and 823 are
fitted in its main frame 821 and are fixed by screwing stop frames
824 and 825. Such a 0.5.times. objective lens 82 is detachably
mounted in the corresponding screw hole 8131 of the rotatable
portion 813 of the revolver 81 with its main frame 821. The
objective lenses 83 have an ordinary magnification. These objective
lenses 83 are also detachably mounted in the corresponding screw
holes (not shown) of the rotatable portion 813 of the revolver
81.
[0125] As shown in FIG. 13, the cube unit 7 has a stationary frame
71 and a turret 72 serving as a cube switching means. The
stationary frame 71 is formed with a male dovetail 711 as shown in
FIG. 15A. The stationary frame 71 is detachably fixed to the arm
602 of the microscope main body 51 through the male dovetail 711.
The stationary frame 71 has a stationary shaft 712 extending
upright in the direction of the observation optical axis 53. The
turret 72 is rotatably held by the stationary shaft 712 as it is
fastened with a nut 714 through bearings 713. In the turret 72, as
shown in FIG. 15A, a plurality of (four in FIG. 15A) male dovetails
721 are formed at the rotation center portion held by the male
dovetails 721, to extend along the stationary shaft 712. For
example, a 0.5.times. auxiliary lens cube 73, serving as one
auxiliary objective lens cube, and a plurality of (three in FIG.
15A) fluorescent cubes 74 having mirror units are detachably fixed
to the turret 72 through the male dovetails 721. When the turret 72
is rotated about the stationary shaft 712 as the center, one of the
cubes 73 and 74 is selectively located on the observation optical
axis 53. In FIG. 15A, the 0.5.times. auxiliary lens cube 73 is
located on the observation optical axis 53.
[0126] The turret 72 has a gear portion 722 on its outer
circumferential edge. A gear 662 of a rotating shaft 661 of a motor
66 meshes with the gear portion 722. The turret 72 is rotated by
the motor 66 about the stationary shaft 712 as the center. Pairs of
click rods 723 equidistantly extend upright from the outer
circumferential edge portion of the turret 72, as shown in FIGS.
15A and 15B. The turret 72 is positioned when a roller 716 at the
distal end of a click spring 715 arranged on the stationary frame
71 side is fitted in one of the pairs of click rods 723.
[0127] In the 0.5.times. auxiliary lens cube 73, 0.5.times.
auxiliary lenses 732, 733, and 734 serving as the second objective
lenses are fitted in a cube main body 731 through spacers 735 and
736 by dropping, and are fixed with a retainer ring 737. Each
fluorescent cube 74 integrally holds an excitation filter 741, a
dichroic mirror 742, and an absorbing filter 743. The excitation
filter 741 wavelength-selectively transmits therethrough reflected
light from the reflected light optical system 56. The dichroic
mirror 742 further wavelength-selectively reflects light
transmitted through the excitation filter 741 toward the objective
lens unit 8 side, and guides the reflected light coaxially with the
observation optical axis 53. The absorbing filter 743 transmits
therethrough the fluorescent image from the sample
wavelength-selectively.
[0128] The microscope main body 51 has a CPU 203 which controls to
rotate the revolver 81 by the motor 65 and rotate the turret 72 by
the motor 66 in an inter-locked manner (see FIG. 16). As will be
described later, the 0.5.times. auxiliary lens cube 73 or one
fluorescent cube 74 of the turret 72 can be automatically inserted
in the observation optical axis 53 to match the 0.5.times.
objective lens 82 or the objective lens 83 which is inserted in the
observation optical axis 53 in accordance with the selected
microscopic method.
[0129] The operation of the embodiment having the above arrangement
will be described.
[0130] When performing reflected light fluorescence observation,
the motor 66 is driven by a selector switch (not shown) in advance
to rotate the turret 72 of the cube unit 7, to insert a fluorescent
cube 74 having a desired observation wavelength in the observation
optical axis 53. Consecutively, the revolver 81 of the objective
lens unit 8 is also rotated by the motor 65 to insert a desired
objective lens 83 other than the 0.5.times. objective lens 82 in
the observation optical axis 53.
[0131] In this state, reflected light from the reflected light
source 54 of the reflected light optical system 56 is focused by
the collector lens 55, is wavelength-selectively transmitted
through the excitation filter 741 of the fluorescent cube 74 of the
cube unit 7, is wavelength-selectively reflected by the dichroic
mirror 742 and is guided to be coaxial with the observation optical
axis 53, and irradiates the surface of the sample on the stage 52
through the objective lens 83 having a desired magnification. A
fluorescent image generated by the sample passes through the
objective lens 83, is wavelength-selectively transmitted through
the dichroic mirror 742 and absorbing filter 743 in the fluorescent
cube 74, and is observed with an image sensing means (not shown),
e.g., an eyepiece or a TV camera, through the tube lens 59.
[0132] When performing transmitted light bright field observation,
at least one of the three fluorescent cubes 74 of the cube unit 7
is removed from the turret 72 in advance.
[0133] First, when performing sample observation with an objective
lens 83 other than the 0.5.times. objective lens 82, the revolver
81 is rotated by the motor 65 to insert a predetermined objective
lens 83 in the observation optical axis 53. Consecutively, the
turret 72 is rotated by the motor 66 to insert an empty hole from
which the fluorescent cube 74 is removed in the observation optical
axis 53.
[0134] In this state, the illumination light transmitted from the
transmitted light source 60 of the transmitted light optical system
63 is focused by the collector lens 61, is reflected by the mirror
62 toward the sample on the stage 52, and is further focused by the
condenser lens 64 to irradiate the sample. Observation light which
has been transmitted through the sample is caused by the objective
lens 83 to pass through the empty hole of the cube unit 7 from
which the fluorescent cube 74 is removed, and is observed with an
image sensing means (not shown), e.g., an eyepiece or a TV camera,
through the tube lens 59.
[0135] When performing observation by using the 0.5.times.
objective lens 82, the revolver 81 is rotated by the motor 65 to
insert the 0.5.times. objective lens 82 in the observation optical
axis 53. Then, in an interlocked manner with rotation of the
revolver 81 by the motor 65, the turret 72 is rotated by the motor
66 to insert the 0.5.times. auxiliary lens cube 73 in the
observation optical axis 53.
[0136] In this state, the illumination light transmitted from the
transmitted light source 60 of the transmitted light optical system
63 is focused by the collector lens 61, is reflected by the mirror
62 toward the sample on the observation optical axis 53, and is
further focused by the condenser lens 64 to irradiate the sample.
Observation light which has been transmitted through the sample is
caused by the 0.5.times. objective lens 82 to further pass through
the 0.5.times. auxiliary lens cube 73 of the cube unit 7, and is
observed with an image sensing means (not shown), e.g., an eyepiece
or a TV camera, through the tube lens 59.
[0137] When observation is to be performed with an objective lens
83 other than the 0.5.times. objective lens 82 while the 0.5.times.
auxiliary lens cube 73 is inserted in the observation optical axis
53, the revolver 81 is rotated by the motor 65 to insert the
objective lens 83 in the observation optical axis 53. Then, in an
interlocked manner with rotation of the revolver 81 by the motor
65, the turret 72 is rotated by the motor 66 to insert the empty
hole from which the fluorescent cube 74 is removed in the
observation optical axis 53.
[0138] Rotation of the revolver 81 by the motor 66 and rotation of
the turret 72 by the motor 66, which is interlocked with it, are
controlled by the CPU 203, on the basis of information on the types
of and positional relationship among the cubes 73 and 74 and lenses
82 and 83, which are input to a memory 202 by an input unit 201 at
the initial setting stage, while referring to information on the
types of and positional relationship among the cubes 73 and 74 and
lenses 82 and 83, which are detected by an objective lens position
detection sensor 204 and a cube position detection sensor 205
during actual motion.
[0139] In FIG. 16, although the objective lens position detection
sensor 204 and the cube position detection sensor 205 are shown as
independent sensors, this conceptual view represent signals. In
fact, the sensors 204 and 205 are arranged at positions where they
can detect the movable portions of the revolver 81 and turret 72,
respectively.
[0140] A case wherein a magnification change is performed from the
0.5.times. objective lens 82 to another objective lens 83 and
simultaneously the microscopic method is switched from transmitted
light bright field observation to reflected light fluorescence
observation will be described. The 0.5.times. objective lens 82 and
the 0.5.times. auxiliary lens cube 73 have already been inserted in
the observation optical axis 53 at the time point of transmitted
light bright field observation. The revolver 81 of the objective
lens unit 8 is rotated by the motor 65 to insert an objective lens
83 having a desired magnification in the observation optical axis
53 to replace the 0.5.times. objective lens 82. In an interlocked
manner with this, the turret 72 of the cube unit 7 is rotated by
the motor 66 to insert a fluorescent cube 74 having a desired
observation wavelength in the observation optical axis 53 to
replace the 0.5.times. auxiliary lens cube 73. Observation with the
objective lens 83 is then performed by following procedures
identical to those employed when performing reflected light
fluorescence observation described above.
[0141] In this case, a switching operation is performed from the
0.5.times. objective lens 82 to the objective lens 83 having a
desired magnification. When a switching operation is performed
between the objective lenses 83, the revolver 81 is rotated by the
motor 65 to insert an objective lens 83 having another
magnification in the observation optical axis 53 to replace the
current objective lens 83. In an interlocked manner with this, the
turret 72 of the cube unit 7 is rotated by the motor 66 to insert a
fluorescent cube 74 having a desired observation wavelength in the
observation optical axis 53 to replace the empty hole from which
the current fluorescent cube 74 is removed.
[0142] Even if the fluorescent cube 74 to be detachably mounted in
the turret 72 of the cube unit 7 is replaced for one of a reflected
light dark field cube (DF) 75, a reflected light bright field cube
(BF) 76, and a reflected light/polarized light observation cube
(PD) 77 shown in FIGS. 17A to 17C in accordance with the
microscopic method, the same effect as that described above can be
expected. The reflected light dark field cube 75 has an annular
mirror 751 and a dark field barrel portion 752. In the reflected
light dark field cube 75, illumination light from the reflected
light source 54 is reflected by the annular mirror 751 toward the
objective lens in the form of an annular illumination light beam.
Observation light from the sample is passed through the dark field
barrel portion 752 so that it is separated from the annular
illumination light beam. The reflected light bright field cube 76
has a half mirror 761. In the reflected light bright field cube 76,
illumination light from the reflected light source 54 is reflected
by the half mirror 761 toward the objective lens, and observation
light from the sample is transmitted through the half mirror 761.
The reflected light/polarized light observation cube 77 has a beam
splitter 771, a polarizer 772, and an analyzer 773. In the
reflected light/polarized light observation cube 77, illumination
light from the reflected light source 54 is linearly polarized by
the polarizer 772 and reflected by the beam splitter 771 toward the
objective lens. Observation light from the sample is transmitted
through the beam splitter 771 and is linearly polarized by the
analyzer 773. The polarizer 772 and the analyzer 773 are arranged
in the so-called crossed nicols state wherein their vibrating
directions are 90.degree. from each other, thus allowing reflected
light/polarized light observation.
[0143] According to the fifth embodiment, a very-low-magnification
objective lens is constituted by the 0.5.times. objective lens 82
and the 0.5.times. auxiliary lens cube 73. The 0.5.times. objective
lens 82 is mounted to the revolver 81, together with another
objective lens 83, such that they can be selectively inserted in
and removed from the observation optical axis 53. The 0.5.times.
auxiliary lens cube 73 is mounted in the turret 72, together with
another fluorescent cube 74, such that they can be selectively
inserted in and removed from the observation optical axis 53. When
the 0.5.times. objective lens 82 is inserted in the observation
optical axis 53 by the revolver 81, the 0.5.times. auxiliary lens
cube 73 is inserted in the observation optical axis 53 by the
turret 72 in an interlocked manner with this, thus allowing
observation with the very-low-magnification objective lens. Since
the 0.5.times. auxiliary lens cube 73 is mounted in the turret 72
together with another fluorescent cube 74, an exclusive mount space
need not be formed, and the entire microscope can be made compact
because of space saving. The height of eye point need not be
increased, so that the operator can perform observation with a
natural posture. Since the 0.5.times. auxiliary lens cube 73 can be
inserted in and removed from the observation optical axis 53 by
utilizing the turret 72 which performs a switching operation among
various types of microscopic methods, a switching operation between
observation with the 0.5.times. objective lens 82 and observation
with another objective lens can be performed easily.
[0144] Since the switching operation of the revolver 81 can be
interlocked with the switching operation of the turret 72, when the
revolver 81 performs a switching operation, not only the
observation magnification is changed but also the fluorescent cube
74 and the 0.5.times. auxiliary lens cube 73 are switched to switch
the microscopic method simultaneously. As a result, a cumbersome
operation can be eliminated to improve the operability. This
arrangement is particularly effective when bright field observation
is performed with a very-low-magnification (0.5.times. in this
case) to decrease discoloration of the sample and fluorescence
observation is performed only at a high magnification.
[0145] Since the 0.5.times. auxiliary lens cube 73 can be
detachably mounted in the turret 72, the 0.5.times. auxiliary lens
cube 73 can be easily replaced for a cube having another desired
magnification, e.g., 0.4.times. to 1.0.times..
[0146] [Sixth Embodiment]
[0147] FIG. 18 shows the schematic arrangement of the sixth
embodiment of the present invention. Portions that are identical to
those of FIG. 13 are denoted by the same reference numerals as in
FIG. 13.
[0148] In this case, a turret 72 of a cube unit 7 detachably fixes
four fluorescent cubes 74. A lens mounting frame 781 is fixed to
the turret 72 immediately above (image side) at least one of the
fluorescent cubes 74. A 0.5.times. auxiliary lens 782 is detachably
arranged in the lens mounting frame 781 as the second objective
lens. Namely, a maximum of four 0.5.times. auxiliary lenses 782 can
be mounted to the four fluorescent cubes 74.
[0149] When such a turret 72 is rotated about a stationary shaft
712 as the center, the fluorescent cubes 74 each having the
0.5.times. auxiliary lens 782 can be selectively located on an
observation optical axis 53. In FIG. 18, the 0.5.times. auxiliary
lens 782 is located on the observation optical axis 53.
[0150] In this arrangement, when performing reflected light
fluorescence observation, at least two fluorescent cubes 74 having
the same observation wavelength are mounted in the turret 72 in
advance. The 0.5.times. auxiliary lens 782 is mounted immediately
above one of the two fluorescent cubes 74.
[0151] In this state, to perform 0.5.times. observation, the turret
72 is rotated by a motor 66 to insert a fluorescent cube 74 having
the 0.5.times. auxiliary lens 782 in the observation optical axis
53. Consecutively, a revolver 81 of a objective lens unit 8 is also
rotated by a motor 65 to insert a 0.5.times. objective lens 82 in
the observation optical axis 53. Then, 0.5.times. reflected light
fluorescence observation is allowed. To perform observation at a
magnification other than 0.5.times., the turret 72 is rotated by
the motor 66 to insert a fluorescent cube 74 not having a
0.5.times. auxiliary lens 782 in the observation optical axis 53.
Consecutively, the revolver 81 of the objective lens unit 8 is also
rotated by the motor 65 to insert an objective lens 83 other than
the 0.5.times. objective lens 82 in the observation optical axis
53. Then, reflected light fluorescence observation with the current
objective lens 83 is allowed.
[0152] To perform transmitted light bright field observation, at
least two fluorescent cubes 74 are removed from the turret 72 to
make the holes empty. The 0.5.times. auxiliary lens 782 is mounted
in one of the empty holes from which the fluorescent cubes 74 are
removed.
[0153] In this state, to perform 0.5.times. observation, the turret
72 is rotated by the motor 66 to insert a empty hole having a
0.5.times. auxiliary lens 782 in the observation optical axis 53.
Consecutively, the revolver 81 of the objective lens unit 8 is also
rotated by the motor 65 to insert the 0.5.times. objective lens 82
in the observation optical axis 53. Then, 0.5X transmitted light
bright field observation is allowed. To perform observation at a
magnification other than 0.5.times., the turret 72 is rotated by
the motor 66 to insert a empty hole, from which the fluorescent
cube 74 is removed, in the observation optical axis 53.
Consecutively, the revolver 81 of the objective lens unit 8 is also
rotated by the motor 65 to insert an objective lens 83 other than
the 0.5.times. objective lens 82 in the observation optical axis
53. Then, transmitted light bright field observation with the
current objective lens 83 is allowed.
[0154] In this manner, the 0.5.times. auxiliary lens 782 is mounted
not in the mount space for the fluorescent cube 74 of the turret 72
but in the turret 72 in this-space. Accordingly, the fluorescent
cube 74 and the 0.5.times. auxiliary lens 782 can be inserted in
the observation optical axis 53 simultaneously, and accordingly
very-low-magnification observation using the 0.5.times. auxiliary
lens 782 can be performed not only in transmitted light bright
field observation but also in fluorescence observation or various
types of other microscopic observations.
[0155] Since the 0.5.times. auxiliary lens 782 is arranged on an
upper side (image side) of the reflected light optical system 56,
when the reflected light irradiates the specimen, the light need
not be transmitted through the 0.5.times. auxiliary lens 782. As a
result, a high transmittance can be obtained and bright
illumination can be performed. In the case of fluorescence
observation, since the reflected light (excitation light) does not
irradiate a member other than the 0.5.times. auxiliary lens 782,
observation is not affected by the self fluorescence caused by the
0.5.times. auxiliary lens 782, and high-contrast observation can be
performed.
[0156] In the above description, reflected light fluorescence
observation and transmitted light bright field observation are
performed by changing the observation magnification. If these two
observation schemes are combined, a magnification switching
operation, e.g., from 0.5.times. transmitted light bright field
observation to reflected light fluorescence observation with the
objective lens 83, and the microscopic method switching operation
can be performed simultaneously. The observation scheme can be
combined with a cube employing a microscopic method other than that
of the fluorescent cube 74, as described with reference to FIGS.
17A to 17C. Furthermore, the turret 72 and the revolver 81 may be
interlocked with each other to perform a switching operation among
various types of cube combinations.
[0157] [Seventh Embodiment]
[0158] FIG. 19 shows the schematic arrangement of the seventh
embodiment of the present invention. Portions that are identical to
those of FIG. 13 are denoted by the same reference numerals as in
FIG. 13.
[0159] In this case, a 0.5.times. auxiliary lens cube 79 has a
polarizer 791, a polarizing beam splitter 792, an analyzer 793, and
a 0.5.times. auxiliary lens 794. The polarizer 791 polarizes
illumination light from a reflected light source 54 into linearly
polarized light whose vibrating direction is perpendicular to the
surface of the sheet of drawing. The polarizing beam splitter 792
selectively reflects the linearly polarized light having a
vibrating direction that has been transmitted through the polarizer
791 toward an objective lens unit 8, guides reflected light to be
coaxial with an observation optical axis 53, and selectively
transmits therethrough, of observation light from the sample,
linearly polarized light which is 90.degree. with respect to the
vibrating direction of the linearly polarized light which has been
transmitted through the polarizer 791. The analyzer 793 polarizes
observation light, which has been transmitted through the
polarizing beam splitter 792, into linearly polarized light in a
direction of crossed nicols with the polarizer 791, such that its
vibrating direction is orthogonal with the observation optical axis
53. The 0.5.times. auxiliary lens 794 serves as the second
objective lens. The 0.5.times. auxiliary lens cube 79 can be
detachably mounted in a turret 72.
[0160] A reflected light bright field cube 80 has a half mirror 801
and can be detachably mounted in the turret 72 together with the
0.5.times. auxiliary lens cube 79.
[0161] A 0.5.times. objective lens 82 detachably mounted on a
revolver 81 of the objective lens unit 8 fixes a .lambda./4 plate
826 at its distal end closest to the sample side. The .lambda./4
plate 826 is set such that the direction of its optical axis is
45.degree. with respect to the vibrating directions of the
polarizer 791 and analyzer 793.
[0162] In this arrangement, when reflected light bright field
observation is to be performed, the 0.5.times. auxiliary lens cube
79 is mounted in the turret 72 together with the reflected light
bright field cube 80. When 0.5.times. observation is to be
performed, the turret 72 is rotated by a motor 66 to insert the
0.5.times. auxiliary lens cube 79 in the observation optical axis
53. Consecutively, the revolver 81 of the objective lens unit 8 is
also rotated by a motor 65 to insert the 0.5.times. objective lens
82 in the observation optical axis 53.
[0163] In this state, illumination light from the reflected light
source 54 is polarized by the polarizer 791 into linearly polarized
light, is reflected by the polarizing beam splitter 792 toward the
objective lens unit 8, is transmitted through the 0.5.times.
auxiliary lens 794 and 0.5.times. objective lens 82, and is further
transmitted through the .lambda./4 plate 826 so as to be polarized
into circularly polarized light, to irradiate the sample.
Observation light reflected by the sample is transmitted through
the .lambda./4 plate 826 so as to be converted into linearly
polarized light in a direction 90.degree. with respect to the
vibrating direction of the linearly polarized light of the
illumination light upon being transmitted through the polarizer
791, is transmitted through the 0.5.times. objective lens 82 and
0.5.times. auxiliary lens 794, is further transmitted so as to
coincide with both the direction of polarized light transmitted
through the polarizing beam splitter 792 and the vibrating
direction of the analyzer 793, and is observed with an image
sensing means (not shown), e.g., an eyepiece or a TV camera,
through the tube lens 59.
[0164] The illumination light which is transmitted through the
polarizer 791 to be polarized into linearly polarized light and is
reflected by the respective lens surfaces of the 0.5.times.
objective lens 82 and 0.5.times. auxiliary lens 794 is not
transmitted through the .lambda./4 plate 826. The polarizing
direction of this illumination light is 90.degree. with respect to
the transmitting and polarizing direction of the polarizing beam
splitter 792 and the vibrating direction of the analyzer 793. This
illumination light is cut by the polarizing beam splitter 792 and
analyzer 793 and does not reach the tube lens 59. As a result,
flare or ghost is prevented.
[0165] When observation is to be performed by using an objective
lens 83 other than the 0.5.times. objective lens 82, the motor 66
is driven to rotate the turret 72 of a cube unit 7 so as to insert
the reflected light bright field cube 80 in the observation optical
axis 53. Consecutively, the revolver 81 of the objective lens unit
8 is also rotated by the motor 65 to insert the objective lens 83
other than the 0.5.times. objective lens 82 in the observation
optical axis 53.
[0166] In this state, illumination light emitted from the reflected
light source 54 is reflected by the half mirror 801 of the
reflected light bright field cube 80 toward an objective lens unit
8, and is transmitted through the objective lenses 83 to irradiate
the sample surface. Observation light reflected by the sample is
transmitted through the objective lens 83 again and through the
half mirror 801 to be observed with an image sensing means (not
shown), e.g., an eyepiece or a TV camera, through the tube lens
59.
[0167] In this manner, in reflected light bright field observation
with the 0.5.times. objective lens 82 which tends to be affected by
ghost or flare, the 0.5.times. auxiliary lens cube 79 integrally
having the polarizer 791, the polarizing beam splitter 792, the
analyzer 793, and the 0.5.times. auxiliary lens 794 is selected.
When observation is to be performed with the high-magnification
objective lens 83, other than the 0.5.times. objective lens 82,
which is not easily affected by ghost or flare, only the 0.5.times.
auxiliary lens cube 79 need be switched to another fluorescent cube
74. Therefore, a cumbersome operation accompanying switching of the
objective lens can be eliminated, thus improving the operability.
In place of the polarizing beam splitter 792 in the 0.5.times.
auxiliary lens cube 79, a half mirror that can branch light may be
used.
[0168] Since the 0.5.times. auxiliary lens 782 is arranged under
(on the 0.5.times. objective lens side of) the reflected light
optical system 56, when reflected light bright field observation is
to be performed, the field stop (F.S.) forms a sharp image in the
same manner as in observation employing an objective lens having
another magnification.
[0169] The F.S. is arranged in the reflected light optical system
(not shown). The F.S. is projected onto the objective lens image
surface for the first time with the tube lens 59 and an F.S.
projection lens in the reflected light optical system which serves
to project the F.S. (not shown). The F.S. is projected onto the
sample surface for the first time with the F.S. projection lens and
an objective lens which projects an objective lens image onto a
regular position with only the tube lens 59. For example, if the
0.5.times. auxiliary lens is arranged between the F.S. projection
lens and the tube lens 59, as in FIG. 18 showing the sixth
embodiment, the F.S. is not projected onto the regular objective
lens image surface.
[0170] Although the turret 72 of the cube unit 7 and the revolver
81 of the objective lens unit 8 are interlocked with each other in
the fifth to seventh embodiments described above, they need not
always be interlocked with each other, but may be switched manually
and not electrically. Although the cube unit 7 is switched by the
turret 72, the present invention is not limited to this, and the
cube unit 7 may be linearly switched with a slider. In the above
description, the objective lens is constituted by two parts, i.e.,
the 0.5.times. objective lens 82 and the 0.5.times. auxiliary lens
794. However, the present invention is not limited to this. For
example, another cube unit may be arranged between the cube unit 7
and the tube lens 59, so that objective lens is divided into three
parts that can be switched in an interlocked manner with each
other.
[0171] As has been described above through the fifth to seventh
embodiments, according to the second aspect of the present
invention, the second objective lens can be selectively inserted in
and removed from the observation optical axis, together with the
plurality of cubes corresponding to different microscopic methods,
with a cube selecting means. An exclusive space for the second
objective lens need not be formed, and the entire microscope can be
made compact because of space economization. The height of eye
point need not be increased, so that the operator can perform
observation with a natural posture.
[0172] The switching operation of the cube switching means can be
interlocked with the objective lens switching means. When the
objective lens switching means is switched, not only the
observation magnification is changed but also the cubes are
switched to switch the microscopic method, providing a good
operability.
[0173] Since the second objective lens can be detachably mounted in
the cube switching means, the second objective lens can be replaced
for one having a desired magnification.
[0174] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *