JP2004085811A - Microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscope usable for both of a confocal laser scanning microscope and a total reflection microscope by switching an optical member. <P>SOLUTION: The microscope is provided with a laser illumination light source 1, an objective lens 6, a scanner 3 arranged between the laser illumination light source and the objective lens for scanning illumination light from the laser illumination light source in at least one direction, a first relay lens system 4 arranged between the scanner and the objective lens, a second relay lens system 5 for converging the illumination light from the first relay lens system onto the object surface of the objective lens, and a third relay lens system (14, 15) for converging the illumination light from the first relay lens system onto the vicinity of the entrance pupil surface of the objective lens. The second relay lens system and the third relay lens system can be exchanged, the illumination light performs scanning illumination of a sample by the scanner when the second relay lens system is inserted into an optical axis and the illumination light performs the total reflection illumination of the sample when the third relay lens system is inserted to the optical axis. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microscope using laser light or the like, and more particularly to a microscope having both functions of a confocal laser scanning microscope and a total reflection microscope.
[0002]
[Prior art]
Conventionally, there are a confocal laser scanning microscope and a total reflection microscope as microscopes using a laser beam. Each of them is mainly used to irradiate a fluorescent specimen to a biological specimen or the like by irradiating the specimen with laser light to excite the specimen, and observe and detect fluorescence generated in the specimen.
[0003]
The confocal laser scanning microscope irradiates a laser beam spot focused on the sample near the diffraction limit of the objective lens while scanning the sample, and places the fluorescent light generated in the irradiated portion of the laser beam at an optically conjugate position. Detect through.
[0004]
In addition, a total internal reflection microscope emits illumination light onto the specimen in close contact with the cover glass from the cover glass side, and enters the illumination light at a critical angle at which the incident light is totally reflected at the boundary surface between the cover glass and the specimen. Using the evanescent wave generated in the region, the vicinity of the boundary surface of the sample is excited to generate fluorescence, and the fluorescence is detected using a CCD camera or the like.
[0005]
The above two types of microscopes use laser light as an illumination light source because it is necessary to focus the illumination light on a specimen or a minute spot on the entrance pupil plane of an objective lens, but each is used only as an independent microscope. I have.
[0006]
[Problems to be solved by the invention]
In recent years, there has been a demand for a microscope that can be used by a single microscope as both a confocal laser scanning microscope and a total internal reflection microscope. Until now, to meet such demands, confocal laser scanning microscopes and total internal reflection microscopes were purchased separately and their optical systems were combined, so almost two microscopes would have to be purchased. However, there is a problem that the apparatus becomes large-scale and expensive.
[0007]
Further, when switching between the optical system for the confocal laser scanning microscope and the optical system for the total internal reflection microscope is performed, there is a problem that the operation is complicated and the switching mechanism is complicated.
[0008]
The present invention has been made in view of the above problems, and provides a microscope that can be used for both a confocal laser scanning microscope and a total internal reflection microscope and can share a control device and the like by simple switching of optical members. It is aimed at.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a laser illumination light source, an objective lens, and an illumination light from the laser illumination light source are arranged between the laser illumination light source and the objective lens and scan in at least one direction. A scanner,
A first relay lens system disposed between the scanner and the objective lens;
A second relay lens system for condensing the illumination light from the first relay lens system on an object plane of the objective lens;
A third relay lens system for condensing the illumination light from the first relay lens system near the entrance pupil plane of the objective lens,
The second relay lens system and the third relay lens system are interchangeable,
When the second relay lens system is inserted in the optical axis, the illumination light can scan and illuminate the sample by the scanner,
A microscope is provided, wherein the illumination light can totally illuminate a sample when the third relay lens system is inserted in an optical axis.
[0010]
In the microscope of the present invention, the first relay lens system and the second relay lens system are arranged such that a light deflecting unit of the scanner and an entrance pupil plane of the objective lens are substantially optically conjugate. Yes,
It is preferable that the first relay lens system and the third relay lens system are arranged such that a light deflecting unit of the scanner and a focal position on the specimen side of the objective lens are substantially optically conjugate.
[0011]
Further, according to the present invention, a laser illumination light source, an objective lens, a scanner disposed between the laser illumination light source and the objective lens, and scanning at least one direction with illumination light from the laser illumination light source,
A first relay lens system disposed between the scanner and the objective lens;
A fixed relay lens system for condensing the illumination light from the first relay lens system on an object plane of the objective lens,
A third relay lens system for condensing the illumination light from the first relay lens system near the entrance pupil plane of the objective lens,
The third relay lens system can be inserted and removed between the first relay lens system and the fixed relay lens system,
When the third relay lens system is off the optical axis, the illumination light can scan and illuminate the sample by the scanner;
A microscope is provided, wherein the illumination light can totally illuminate a sample when the third relay lens system is inserted in an optical axis.
[0012]
In the microscope of the present invention, the first relay lens system and the fixed relay lens system are arranged so that a light deflecting unit of the scanner and an entrance pupil plane of the objective lens are substantially optically conjugate. ,
The first relay lens system, the fixed relay lens system, and the third relay lens system are arranged such that an optical deflecting unit of the scanner and a focal position on the specimen side of the objective lens are substantially optically conjugate. Is desirable.
[0013]
Further, in the microscope of the present invention, a first observation optical system provided between the laser illumination light source and the scanner,
An observation light path switching optical element provided so as to be insertable and removable between the objective lens and the third relay lens system;
A second observation optical system provided near the observation optical path switching optical element,
When the second relay lens system or the fixed relay lens system is inserted into the optical axis and the observation optical path switching optical element is off the optical axis, light from the sample is transmitted to the first observation optical system. Can be observed with
When the third relay lens system is inserted in the optical axis and the observation optical path switching optical element is inserted in the optical axis, light from the sample passes through the observation optical path switching optical element through the second optical path. It is desirable to be able to observe with the observation optical system.
[0014]
Further, in the microscope of the present invention, it is preferable that the observation optical path switching optical element includes a beam splitter and an illumination light cut filter which are arranged at approximately 45 degrees with respect to the optical axis.
[0015]
In the microscope of the present invention, it is preferable that the third relay lens system is movable in an optical axis direction in order to focus the illumination light near an entrance pupil plane of the objective lens.
[0016]
In the microscope of the present invention, the third relay lens system is inserted and removed so that the observation optical path switching optical element is inserted into the optical axis only when the third relay lens system is inserted into the optical axis. It is desirable that the operation and the insertion / removal operation of the observation optical path switching element are linked.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a schematic configuration diagram when a microscope according to the first embodiment of the present invention is used as a confocal laser scanning microscope, and FIG. FIG. 2 shows a schematic configuration diagram when used as a microscope. FIG. 3 is a schematic diagram illustrating a configuration in which the microscope according to the second embodiment of the present invention is used as a confocal laser scanning microscope, and FIG. 4 is a diagram illustrating the microscope according to the second embodiment of the present invention. FIG. 2 shows a schematic configuration diagram when used as a microscope.
(1st Embodiment)
FIG. 1 and FIG. 2 are schematic configuration diagrams of a microscope according to a first embodiment of the present invention. In this microscope, a confocal laser scanning microscope and a total internal reflection microscope are connected to each other by inserting, removing, and replacing optical members. It can be used for both. Hereinafter, each case of the confocal laser scanning microscope and the total reflection microscope will be described.
[0019]
When used as a confocal laser scanning microscope, in FIG. 1, illumination light 2 emitted from a laser illumination light source 1 enters a two-dimensional scanner 3, is emitted from the two-dimensional scanner 3, and is connected to a first relay lens system 4. The light enters the objective lens 6 via the second relay lens system 5 and is focused on the sample 7.
[0020]
The light (reflected light or fluorescent light, etc.) from the specimen 7 is condensed by the objective lens 6 and passes through the same optical path as the illumination light 2 and between the laser illumination light source 1 and the two-dimensional scanner 3 with respect to the optical axis. The light is reflected by a beam splitter 8 disposed at an angle, forms an image on a photomultiplier 11 via an imaging lens 9 and a pinhole 10, and is observed on a monitor (not shown). Here, the beam splitter 8, the imaging lens 9, the pinhole 10, and the photomultiplier 11 constitute a first observation optical system.
[0021]
The two-dimensional scanner 3 controls two scanners whose light deflection directions are orthogonal to each other with the control circuit 12, and scans the illumination light 2 in a two-dimensional plane of the sample 7.
[0022]
The scanning range and scanning speed of the illumination light 2 are determined based on a control signal sent from the personal computer 13 to the control circuit 12.
[0023]
The first relay lens system 4 and the second relay lens system 5 are arranged such that the light deflecting section of the two-dimensional scanner 3 and the entrance pupil plane I of the objective lens 6 are substantially optically conjugate. When the two-dimensional scanner 3 is formed by a mirror, the light polarizing portion of the two-dimensional scanner 3 may be a mirror surface thereof.
[0024]
Thus, the microscope of the present invention can be used as a confocal laser scanning microscope.
[0025]
When used as a total reflection microscope, in FIG. 2, the illumination light 2 emitted from the laser illumination light source 1 enters the two-dimensional scanner 3, exits from the two-dimensional scanner 3, and enters the first relay lens system 4. The light is condensed near the entrance pupil plane I of the objective lens 6 via the relay lens system 14 and the relay lens system 15 as the third relay lens system, and is emitted from the objective lens 6. In the vicinity of the entrance pupil plane I, the pupil position is also included. Since the illumination light 2 is collected near the entrance pupil plane I of the objective lens 6, the specimen 7 is irradiated with substantially parallel light from the objective lens 6.
[0026]
The illumination light 2 emitted from the objective lens 6 passes through the cover glass 16 and irradiates the sample 7. For example, the specimen 7 was subjected to fluorescent staining of the cultured cells adsorbed on the cover glass 16 and the surrounding area was filled with a salt solution for keeping the cells alive, the fixed cells were subjected to fluorescent staining, and the tissue section was subjected to fluorescent staining. Things etc. are used. The illumination range is, for example, about 100 μm in diameter when a 100 × objective lens 6 is used.
[0027]
The position where the illumination light 2 is incident on the entrance pupil plane I of the objective lens 6 can be freely changed by controlling the scanning operation of the two-dimensional scanner 3 based on a control signal sent from the personal computer 13 to the control circuit 12. Can be.
[0028]
When the illumination light 2 is incident near the center of the entrance pupil plane I of the objective lens 6, the illumination light 2 is emitted in a substantially vertical direction from near the center of the objective lens 6. When the incident position of the illumination light 2 is moved from the center of the entrance pupil plane I of the objective lens 6 toward the peripheral portion by the scanning control of the two-dimensional scanner 3, the light emitted from the objective lens 6 is tilted accordingly, The illumination light 2 emitted from the lens 6 is totally reflected at the boundary surface S between the sample 7 and the cover glass 16.
[0029]
In the state of total reflection, an evanescent wave is generated near the boundary surface S between the sample 7 and the cover glass 11, and only the vicinity of the boundary surface S of the sample 7 is selectively excited by the evanescent wave.
[0030]
Further, while in the total reflection state, the vicinity of the center of the visual field is illuminated with the illumination light 2, and the illumination position (the area where the illumination light 2 is totally reflected) is the illumination light 2 on the entrance pupil plane I. Hardly changes even if the incident position changes.
[0031]
Light (fluorescence) from the specimen 7 excited by the evanescent wave is condensed by the objective lens 6 and reflected by a beam splitter 17 arranged at approximately 45 degrees with respect to the optical axis. An image is formed on an imaging device (for example, a CCD camera or the like) 20 via a lens 19, processed by an image generation circuit 21, and displayed on a monitor of the personal computer 13. Here, an optical path switching optical element 23b is configured by the beam splitter 17 and the illumination light cut filter 18, and a second observation optical system is configured by the imaging lens 19 and the imaging device 20.
[0032]
Thus, the microscope of the present invention can be used as a total internal reflection microscope.
[0033]
The first relay lens system 4 and the third relay lens system (14, 15) are arranged such that the light deflecting section of the two-dimensional scanner 3 and the focal position on the sample side of the objective lens 6 are substantially optically conjugate. Have been. When the two-dimensional scanner 3 is formed by a mirror, the light polarizing portion of the two-dimensional scanner 3 may be a mirror surface thereof.
[0034]
In the first embodiment, in order to switch between the confocal laser scanning microscope and the total reflection microscope, the second relay lens system 5 and the third relay lens system (14, 15) are exchanged with respect to the optical axis. It is supported by a lens support member 22 that enables it. In the first embodiment, the lens support member 22 has a rotation mechanism, and the second relay lens system 5 and the third relay lens system (14, 15) are arranged so as to be rotatable about the rotation shaft 22a. (Eg, a rotating turret, etc.). By rotating the lens support member 22 about the rotation axis 22a, the second relay lens system 5 and the third relay lens system (14, 15) can be exchanged on the optical axis.
[0035]
The lens support member 22 is formed so as to be movable in the optical axis direction after the third relay lens system (14, 15) is inserted into the optical axis. Accordingly, even when the position of the entrance pupil plane I of the objective lens 6 is displaced in the optical axis direction (for example, when the objective lens 6 is replaced), the illumination light 2 can be provided near the entrance pupil plane I of the objective lens 6. It can be adjusted so that the light is focused.
[0036]
Further, an optical path splitting optical element 23b integrally provided with a beam splitter 17 and an illumination light cut filter 18 used for observation with a total reflection microscope is supported by an optical element supporting member 23 having a rotating mechanism. By inserting the optical path splitting optical element 23b into the optical axis by the optical element supporting member 23 and introducing light from the sample into the second observation optical system, it becomes possible to perform total internal reflection microscope observation.
[0037]
As described above, by making the second relay lens system 5 and the third relay lens system (14, 15) interchangeable and by allowing the optical path switching optical element 23b to be inserted into and detached from the optical axis, observation with a confocal laser microscope is possible. Switching of the total reflection microscope observation becomes possible.
[0038]
Note that a switching mechanism other than a rotation mechanism may be used for exchanging the second relay lens system 5 and the third relay lens system (14, 15) and inserting / removing the optical path switching optical element 234b.
[0039]
The rotation mechanism and the like are respectively supported at predetermined positions of a microscope main body (not shown).
[0040]
Note that the lens support member 22 and the optical element support member 23 may be configured so that their operations are interlocked using a gear mechanism or a motor drive.
[0041]
The above-mentioned interlocking operation is desirably configured so that the optical path switching optical element 23b is inserted into the optical axis when the third relay lens system (14, 15) is inserted into the optical axis.
(2nd Embodiment)
Next, an optical scanning microscope according to a second embodiment of the present invention will be described with reference to the drawings.
[0042]
3 and 4 show a microscope according to a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that the second relay lens system 5 of the first embodiment is changed to a fixed relay lens system 25, and the position of insertion / removal of the third relay lens system 24. There is a difference. 3 and 4, the fixed relay lens system 25 corresponds to a lens such as a second objective lens of an infinite system microscope commonly used by both the confocal laser scanning microscope and the total internal reflection microscope. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0043]
When used as a confocal laser scanning microscope, in FIG. 3, the illumination light 2 emitted from the laser illumination light source 1 enters the two-dimensional scanner 3, exits from the two-dimensional scanner 3, and communicates with the first relay lens system 4. The light enters the objective lens 6 via the fixed relay lens system 25 and is focused on the sample 7.
[0044]
The light (reflected light or fluorescent light, etc.) from the specimen 7 is condensed by the objective lens 6 and passes through the same optical path as the illumination light 2 and between the laser illumination light source 1 and the two-dimensional scanner 3 with respect to the optical axis. The light is reflected by a beam splitter 8 disposed at an angle, forms an image on a photomultiplier 11 via an imaging lens 9 and a pinhole 10, and is observed on a monitor (not shown) or the like. Here, the beam splitter 8, the imaging lens 9, the pinhole 10, and the photomultiplier 11 constitute a first observation optical system.
[0045]
The control method of the two-dimensional scanner 3 and the like are the same as those in the first embodiment, and a description thereof will be omitted.
[0046]
The first relay lens system 4 and the fixed relay lens system 25 are arranged such that the light deflecting unit of the two-dimensional scanner 3 and the entrance pupil plane I of the objective lens 6 are substantially optically conjugate. When the two-dimensional scanner 3 is formed by a mirror, the light polarizing portion of the two-dimensional scanner 3 may be a mirror surface thereof.
[0047]
When used as a total reflection microscope, in FIG. 4, the illumination light 2 emitted from the laser illumination light source 1 enters the two-dimensional scanner 3 and exits from the two-dimensional scanner 3, and the first relay lens system 4 and the second The light is condensed near the entrance pupil plane I of the objective lens 6 via the three relay lens system 24 and the fixed relay lens system 25 and exits from the objective lens 6. In the vicinity of the entrance pupil plane I, the pupil position is also included.
[0048]
Since the illumination light 2 is collected near the entrance pupil plane I of the objective lens 6, substantially parallel light is emitted from the objective lens 6 toward the sample 7. The method for setting the state of total reflection illumination is the same as in the first embodiment, and a description thereof will be omitted.
[0049]
Then, light (fluorescence) from the specimen 7 excited by the evanescent wave generated in the state of total reflection illumination is condensed by the objective lens 6 and reflected by the beam splitter 17 arranged at approximately 45 degrees with respect to the optical axis. An image is formed on an image pickup device (for example, a CCD camera or the like) 20 through an illumination light cut filter 18 and an image forming lens 19, processed by an image generation circuit 21, and displayed on the monitor of the personal computer 13. Here, an optical path switching optical element 23b is configured by the beam splitter 17 and the illumination light cut filter 18, and a second observation optical system is configured by the imaging lens 19 and the imaging device 20.
[0050]
Thus, the microscope of the present invention can be used as a total internal reflection microscope.
[0051]
The first relay lens system 4, the third relay lens system 24, and the fixed relay lens system 25 are configured such that the light deflecting unit of the two-dimensional scanner 3 and the focal position of the objective lens 6 on the sample side are substantially optically conjugate. Are located in When the two-dimensional scanner 3 is formed by a mirror, the light polarizing portion of the two-dimensional scanner 3 may be a mirror surface thereof.
[0052]
In the second embodiment, switching between the confocal laser scanning microscope and the total internal reflection microscope is performed by supporting the third relay lens system 24 on the lens support member 26 and switching the first relay lens system 4 and the fixed relay lens system 25. This is performed by inserting and removing the optical axis between them (moving in the horizontal direction in the figure).
[0053]
The lens support member 26 is formed so as to be movable in the optical axis direction after the third relay lens system 24 is inserted into the optical axis. Accordingly, even when the position of the entrance pupil plane I of the objective lens 6 is displaced in the optical axis direction (for example, when the objective lens 6 is replaced), the illumination light 2 can be provided near the entrance pupil plane I of the objective lens 6. It can be adjusted so that the light is focused.
[0054]
Note that the insertion and removal of the third relay lens system 24 may be performed by a rotation mechanism or the like in addition to the above-described horizontal movement.
[0055]
An optical path switching optical element 23b integrally provided with the beam splitter 17 and the illumination light cut filter 18 used for observation with a total reflection microscope is supported by an optical element support member 23 having a rotating mechanism. By inserting the optical path splitting optical element 23b into the optical axis by the optical element supporting member 23 and introducing light from the sample into the second observation optical system, it becomes possible to perform total reflection microscope observation.
[0056]
As described above, the third relay lens system 24 is removably disposed between the first relay lens system 4 and the second relay lens system 5, and the optical path switching optical element 23b is disposed removably on the optical axis. This makes it possible to switch between observation with a confocal laser microscope and observation with a total internal reflection microscope.
[0057]
Note that a switching mechanism other than the rotation mechanism may be used for inserting and removing the optical element from the optical axis.
[0058]
The rotation mechanism and the like are respectively supported at predetermined positions of a microscope main body (not shown).
[0059]
Note that the lens support member 26 and the optical element support member 23 may be configured so that their operations are interlocked using a gear mechanism or a motor drive.
[0060]
In addition, it is desirable that the above-mentioned interlocking operation is configured such that the optical path switching optical element 23b is inserted into the optical axis when the third relay lens system 24 is inserted into the optical axis.
[0061]
It should be noted that this embodiment is merely an example, and is not limited to this configuration or shape, and can be appropriately modified or changed within the scope of the present invention.
[0062]
【The invention's effect】
As described above, the present invention can provide a microscope that can be used for both a confocal laser scanning microscope and a total internal reflection microscope and that can also use a control device and the like by simply switching optical members.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram when a microscope according to a first embodiment of the present invention is used as a confocal laser scanning microscope.
FIG. 2 is a schematic configuration diagram when the microscope according to the first embodiment of the present invention is used as a total reflection microscope.
FIG. 3 is a schematic configuration diagram when a microscope according to a second embodiment of the present invention is used as a confocal laser scanning microscope.
FIG. 4 is a schematic configuration diagram when a microscope according to a second embodiment of the present invention is used as a total reflection microscope.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 laser illumination light source 2 illumination light 3 two-dimensional scanner 4 first relay lens system 5 second relay lens system 6 objective lens 7 sample 8 beam splitter 9 imaging lens 10 pinhole 11 photomultiplier 12 control circuit 13 personal computer 14 relay Lens system (third relay lens system)
15 relay lens system (third relay lens system)
Reference Signs List 16 cover glass 17 beam splitter 18 illumination light cut filter 19 imaging lens 20 imaging device 21 image generation circuit 22 lens support members 22a, 23a rotation axis 23b optical path switching optical element 23 optical element support member 24 third relay lens system 25 fixed relay Lens system 26 Lens support member

Claims (8)

A laser illumination light source,
An objective lens,
A scanner that is arranged between the laser illumination light source and the objective lens and scans illumination light from the laser illumination light source in at least one direction;
A first relay lens system disposed between the scanner and the objective lens;
A second relay lens system for condensing the illumination light from the first relay lens system on an object plane of the objective lens;
A third relay lens system for condensing the illumination light from the first relay lens system near the entrance pupil plane of the objective lens,
The second relay lens system and the third relay lens system are interchangeable,
When the second relay lens system is inserted in the optical axis, the illumination light can scan and illuminate the sample by the scanner,
A microscope, wherein the illumination light can totally illuminate a sample when the third relay lens system is inserted in an optical axis. The first relay lens system and the second relay lens system are arranged such that a light deflecting unit of the scanner and an entrance pupil plane of the objective lens are substantially optically conjugate,
The first relay lens system and the third relay lens system are arranged such that a light deflecting unit of the scanner and a focal position on the specimen side of the objective lens are substantially optically conjugate. The microscope according to claim 1. A laser illumination light source,
An objective lens,
A scanner that is arranged between the laser illumination light source and the objective lens and scans illumination light from the laser illumination light source in at least one direction;
A first relay lens system disposed between the scanner and the objective lens;
A fixed relay lens system for condensing the illumination light from the first relay lens system on an object plane of the objective lens,
A third relay lens system for condensing the illumination light from the first relay lens system near the entrance pupil plane of the objective lens,
The third relay lens system can be inserted and removed between the first relay lens system and the fixed relay lens system,
When the third relay lens system is off the optical axis, the illumination light can scan and illuminate the sample by the scanner;
A microscope, wherein the illumination light can totally illuminate a sample when the third relay lens system is inserted in an optical axis. The first relay lens system and the fixed relay lens system are arranged such that the light deflecting unit of the scanner and the entrance pupil plane of the objective lens are substantially optically conjugate,
The first relay lens system, the fixed relay lens system, and the third relay lens system are arranged such that an optical deflecting unit of the scanner and a focal position on the specimen side of the objective lens are substantially optically conjugate. The microscope according to claim 3, wherein the microscope is provided. A first observation optical system provided between the laser illumination light source and the scanner,
An observation light path switching optical element provided so as to be insertable and removable between the objective lens and the third relay lens system;
A second observation optical system provided near the observation optical path switching optical element,
When the second relay lens system or the fixed relay lens system is inserted into the optical axis and the observation optical path switching optical element is off the optical axis, light from the sample is transmitted to the first observation optical system. Can be observed with
When the third relay lens system is inserted in the optical axis and the observation optical path switching optical element is inserted in the optical axis, light from the sample passes through the observation optical path switching optical element through the second optical path. The microscope according to claim 1, wherein the microscope can be observed with the observation optical system. The microscope according to claim 5, wherein the observation optical path switching optical element includes a beam splitter and an illumination light cut filter arranged at approximately 45 degrees with respect to an optical axis. 7. The optical system according to claim 1, wherein the third relay lens system is movable in an optical axis direction so as to focus the illumination light near an entrance pupil plane of the objective lens. The microscope according to 1. Only when the third relay lens system is inserted on the optical axis, the insertion / removal operation of the third relay lens system and the operation of the observation optical path switching element are performed so that the observation optical path switching optical element is inserted on the optical axis. The microscope according to any one of claims 1 to 7, wherein the insertion / removal operation is interlocked.

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