JP2000056232A - Microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable-power microscope in which an observation position is hardly deviated even in the case of varying a power. SOLUTION: The microscope is provided with an objective lens system 2 for condensing light from a sample surface 1, an image forming lens system 6 which is prepared for forming the image of a luminous flux condensed by the objective lens system 2 and which is fixed relative to the objective lens system 2, plural relay optical systems 41 and 41a whose power are different from each other and for relaying the luminous flux condensed by the objective lens system 2 to the image forming lens system 6, and switching mechanisms 11 and 12 for mutually switching plural relay optical systems 41 and 41a, and the optical systems 41 and 41a are constituted by including 1st lens groups 3 and 3a and 2nd lens groups 5 and 5a, respectively, and the 1st and 2nd lens groups are arranged so that the front focus of the 1st lens groups 3 and 3a may be almost aligned with the pupil conjugate surface of the objective lens system 2 and the front focus of the 2nd lens groups 5 and 5a may be almost aligned with the rear focus of the 1st lens groups 3 and 3a. The image forming lens system 6 is fixed relative to the objective lens system 2, then, the observation position of the microscope is hardly deviated, and also, the microscope is provided with plural relay optical systems whose power are different from each other and also provided with the switching mechanisms for switching the relay systems, then, the power of the microscope is varied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable magnification microscope, and more particularly to a variable magnification microscope in which an observation position is not easily shifted even when the magnification is changed.

[0002]

2. Description of the Related Art As shown in FIG. 4, a variable magnification mechanism in a microscope apparatus has objective lenses 102 and 10 having different focal lengths.
2a is attached to the revolver 113, and the revolver 113
By rotating the lens, the focal length of the objective lens was changed to switch the imaging magnification. Objective lenses 102, 102
By standardizing the mounting position of “a” and the position of the exit pupil so that the objective lens mounted on the revolver 113 can be replaced, the changeable magnification can be further increased.

[0003]

However, according to the above-described conventional microscope, there is a problem that the observation position of the sample 1 is shifted if there is an error in the rotation stop position of the revolver 113. In particular, in a microscope using a finite objective lens, if there is an error in the rotation stop position of the revolver 113, the optical axis of the objective lens 102 or 102a and the optical axis of the eyepiece 108 deviate, and further magnification is applied. As a result, the image position of the sample 1 moves and an image is formed. In a microscope using an infinity objective lens, an imaging lens 106 for forming an image is disposed between the objective lens 102 and an eyepiece 108 as shown in FIG. Since the light beam emitted from one point on the sample surface 1 travels in parallel between the lenses 106, there is no image shift due to a shift in the optical axis of the objective lens 102 and the imaging lens 106 which may be an imaging optical system.

Here, when the revolver 113 is rotated to change the objective lens from the objective lens 102 to the objective lens 102a having a different magnification, the microscope main body including the eyepiece 108 and the sample 1 are not moved. The position where the optical axis of the objective lens 102a intersects the sample surface 1, that is, the observation position, should originally be the intersection 101A between the optical axis of the imaging lens 106 and the sample surface. If there is an error, the image is shifted to the intersection 101B between the optical axis of the objective lens 102a and the sample surface, and the image is also shifted.

For this reason, in the conventional microscope, whether it is a finite system or an infinite system, the rotation stop position accuracy of the revolver 113 must be extremely strictly suppressed. However, despite the fact that the magnification is frequently changed, the revolver 113 to which a plurality of objective lenses are attached is structurally limited in size. It was difficult to control it strictly, and this caused an increase in processing costs. Therefore, an object of the present invention is to provide a variable magnification microscope in which the observation position is not easily shifted even when the magnification is changed.

[0006]

In order to achieve the above object, a microscope according to the first aspect of the present invention comprises an objective lens system 2 for condensing light from a sample surface 1 as shown in FIG.
An imaging lens system 6 fixed to the objective lens system 2 for imaging a light beam condensed by the objective lens system 2
And; the light beam condensed by the objective lens system 2 is converted into an imaging lens system 6
A plurality of relay optical systems 41 and 41a having different magnifications from each other; switching mechanisms 11 and 12 for mutually switching the plurality of relay optical systems 41 and 41a; and a plurality of relay optical systems 41 and 41a, respectively. First lens group 3,
3a and the second lens group 5, 5a, the front focal point of the first lens group 3, 3a substantially coincides with the pupil conjugate plane of the objective lens system 2, and the second lens group 5, 5a Is arranged such that the front focal point of the first lens group substantially coincides with the rear focal point of the first lens units 3 and 3a. Here, the pupil conjugate plane of the objective lens system 2 may of course be the exit pupil of the objective lens system 2 itself.

With this configuration, since the imaging lens system 6 is fixed relative to the objective lens system 2,
Since the observation position of the microscope is unlikely to shift and a plurality of relay optical systems having different magnifications are provided and a switching mechanism for switching between them is provided, the magnification of the microscope can be changed.

In the microscope described above, an aperture limiting stop may be arranged on the pupil conjugate plane closer to the sample surface than the first lens groups 3 and 3a. The pupil conjugate plane referred to here may be the pupil itself, not limited to the pupil conjugate plane where the front focal point of the first lens group coincides, but may be any pupil conjugate plane. With this configuration, when the plurality of relay optical systems 41 and 41a are exchanged, even if the position of the optical axis of the exchanged relay optical system is shifted from the position of the optical axis of the relay optical system before the exchange, The position where the light beam from the observation position on the sample surface passes through the aperture limiting diaphragm does not shift.

In the above-mentioned microscope, as described in claim 3, and as shown in FIG. 3, light from the sample surface 1 is placed in an optical path between the sample surface 1 and the relay optical systems 41 and 41a. And a sample surface 1 via the branching system 15
And an autofocus optical system 18 for detecting a state of alignment between the objective lens system 2 and the object plane 1. Here, the branch system 15 is a beam splitter such as a dichroic mirror or a half mirror. With this configuration, by attaching the branch system between the relay optical system and the sample surface, the autofocus function can be operated regardless of the observation magnification, so that observation can be performed while always applying high-precision focus. it can. Therefore, even if the magnification is changed, the focus position is not adjusted again, so that the observation can be performed efficiently.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding members are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a schematic sectional view of a microscope according to a first embodiment of the present invention. In the figure, a base 40 on which the sample 1 is placed is provided with an illumination optical system (not shown) for illuminating the sample 1 by transmission or epi-illumination. Above the base 40 in the figure, there is provided an objective lens 2 which is an objective optical system that collects light from the sample surface 1 and converts the light into a parallel light beam. An image forming lens 6 as an image forming optical system is provided with the optical axis thereof substantially coincident with the optical axis of the objective lens 2 with the optical system 41a interposed therebetween, and further above the image forming surface 7 of the image forming lens 6. An eyepiece lens 8 serving as an eyepiece optical system is provided on both sides. It is configured such that an enlarged image of the sample 1 can be observed by the human eyes 9 from above the eyepiece 8.

[0012] Between the objective lens 2 and the imaging lens 6,
Relay lens systems 41 and 4 as a plurality of variable magnification relay optical systems
1a is provided. Although only two relay lens systems 41 and 41a are shown in FIG. 1, actually two or more relay lens systems may be prepared. For example, 3 to 5 are typical numbers.

In FIG. 1, a relay optical system 41 includes a first lens group 3 and a second lens group 5.
The front focus of the first lens group 3 substantially coincides with the pupil plane P1 of the objective lens system 2, and the front focus of the second lens group 5 is the first focus.
The lens group 3 is arranged so as to substantially coincide with the rear focal point. Here, the front focal point of the first lens group 3 is not limited to the pupil plane P1 of the objective lens system 2, but may be substantially coincident with the pupil conjugate plane. The rear focal point of the second lens group 5 is arranged so as to coincide with the front focal point of the imaging lens 6. In the figure, the relay optical system 41a has the same configuration as the relay optical system 41. Here, the first lens group 3a of the relay optical system 41a corresponds to the first lens group 3, the second lens group 5a corresponds to the second lens group 5,
Corresponding.

The first lens groups 3 and 3a and the second lens groups 5 and 5a of the variable power relay optical systems 41 and 41a have different lengths depending on the magnification to be observed and the total length of the variable power relay optical systems 41 and 41a. Are fixed so that the focal length is constant. Also, the variable magnification relay optical system 41,
41a is a variable power relay lens barrel 10, 10a, respectively.
Is fixedly housed. And a plurality of, for example, 3-5
A plurality of lens barrels typified by lens barrels 10 and 10a accommodating the variable power relay lens system of the group are fixedly attached to a turret 11. The turret 11 is rotated around a rotation axis parallel to the common optical axis of the objective lens 2 and the imaging lens 6 by a motor 12 or the like as a driving device, and the observation magnification is changed by switching a variable magnification relay optical system. It is configured to be able to. Here, the switching mechanism of the present invention includes the turret 11 and the motor 12.

The operation of the microscope according to the first embodiment will be described with reference to FIG. The light beam from the sample surface 1 illuminated by the illumination device (not shown) is condensed by the objective lens 2 and becomes a parallel light beam. The first lens group 3 forms an image on the intermediate imaging plane 4 at the rear focal position of the first lens group 3 located in the lens barrel 10. The light beam that has passed through the intermediate image forming surface 4 spreads again, and becomes a light beam that is parallel to the intermediate image forming surface 4 by the second lens group 5 whose front focal position is matched. The parallel luminous flux emitted from the second lens group 5 is condensed on an imaging surface 7 by an imaging lens 6 to form an image of the sample 1.
The sample image formed on the imaging surface 7 may be observed by enlarging it with an eyepiece 8, or an image sensor such as a CCD may be arranged on the imaging surface 7 to convert the image into an electric signal by photoelectric conversion. You may observe on a monitor.

To observe the sample 1 at different magnifications,
The turret 11 is rotated by rotating the motor 12, and the variable power relay lens system 4 is used instead of the variable power relay lens system 41.
What is necessary is just to set 1a between the objective lens 2 and the imaging lens 6, and to observe.

Referring to FIG. 2, an image forming state when a stop position error occurs due to the turret 11 will be described. It is assumed that the turret 11 is rotated and the variable magnification relay system 41a is replaced with the variable magnification relay optical system 41. Originally, the optical axis of the optical system, particularly the optical axis of the variable magnification relay optical system 41 (3 to 5) must stop at the position of the common optical axis AX of the objective lens 2 and the imaging lens 6. On the other hand, it is shifted and optical axis A
Consider a case in which the optical axes of the variable magnification relay optical systems 3 to 5 are stopped at the positions indicated by BX in the figure, which are slightly translated from X.

The light beam emitted from the intersection of the sample surface 1 and the optical axis AX of the objective lens 2 is a light beam parallel to the optical axis AX at the image forming position on the intermediate image forming surface 4 by the first lens group 3. The light passes through the intersection of the variable magnification relay optical systems 3 to 5 with the optical axis BX. If the optical axes of the variable magnification relay optical systems 3 to 5 are shifted to positions indicated by BX in the figure, the passing position on the intermediate image plane 4 is different from the intersection with the optical axis AX of the objective lens 2, On the intermediate image plane 4 which is the front focal position of the lens group 5 of the second lens group 5, the light beam passes through the optical axis BX of the second lens group 5, so that when the light beam passes through the second lens group 5, the light of the objective lens 2 again Axis A
It becomes a light beam parallel to X. For this reason, since the imaging lens 6 forms an image at the intersection with the optical axis AX on the imaging plane 7 which is the focal plane, no image shift is observed.

If necessary, an aperture stop may be provided on the pupil plane P1 or the pupil conjugate plane P2 of the objective lens 2 to limit the numerical aperture for observation. However, as can be seen from FIG. 2, if the optical axis of the variable magnification relay optical system 41 is shifted on the pupil conjugate plane P2, the position through which the light beam passes will be shifted. It is desirable to provide an aperture stop on the pupil plane P1 on the object side of the lens group 3 of.

A second embodiment of the present invention will be described with reference to FIG. In the microscope described above, in particular, in an optical system for a measuring instrument for performing not only observation but also line width measurement, the center of a light beam contributing to image formation is perpendicular to the surface of the sample 1. Since it is necessary to be telecentric, it is necessary not to be affected by the displacement of the optical axis of the variable magnification relay optical system 41. However, since the pupil of the objective lens 2 is often formed so as to be inside the objective lens 2, an aperture stop cannot be provided directly on the pupil plane. Therefore, as shown in FIG. 3, telecentric relay optical systems 16 and 17 are inserted between the objective lens 2 and the variable power relay optical systems 3 to 5, and the variable power relay optical systems 3 to 5 are inserted.
It is desirable to provide an aperture stop 14 on the object-side pupil conjugate plane independently of the variable magnification relay optical systems 3-5. In order to change the numerical aperture of the aperture stop 14 as necessary, a stop mechanism such as an iris stop which hardly causes eccentricity or a turret type stop mechanism having high-accuracy position reproducibility may be arranged.

In FIG. 3, a dichroic mirror 15 as a branch system is provided on the exit side of the objective lens 2 to add an autofocus function.
The light beam is branched to 8. The autofocus optical system 18 detects a focus shift on the surface to be measured of the sample 1 using infrared light or the like that does not affect observation, so that the dichroic mirror 15 that transmits visible light and reflects infrared light is used. Branch using In general, the autofocus optical system 18 has higher sensitivity to defocus on the sample surface as the numerical aperture of the objective lens 2 is larger. As shown in FIG. 3, when the branching system 15 is disposed between the objective lens 2 and the telecentric relay optical systems 16 and 17, the sample surface is always used with the maximum numerical aperture of the objective lens 2 regardless of the observation magnification. Can be detected, so that observation can be performed while always focusing with high accuracy.

An example of the autofocus optical system 18 will be described with reference to FIG. The dichroic mirror 15
The half mirror 51 is arranged at an angle of about 45 degrees with respect to the optical axis AX, and the deflection direction of the half mirror 51 is arranged at an angle of about 45 degrees with respect to the deflected optical axis. A condenser lens 52 is arranged in the deflection direction of the half mirror 51, and a point light source 53 is arranged ahead of the condenser lens 52. A point light source 53 includes a light shielding plate 54 having a pinhole formed therein, and a condenser lens 52 with respect to the light shielding plate 54.
And a light source 55 such as an infrared lamp placed on the opposite side of the light source. A knife edge 56 is provided between the condenser lens 52 and the half mirror 51 to shield half of the optical axis. The position of the point light source (pinhole) 53 is set to a position conjugate with the sample surface when the sample surface 1 is focused on the microscope.

An image forming lens 57 is provided in the direction in which the light passes through the half mirror 51 from the dichroic mirror 15 and travels straight, and a screen 58 is provided on the image forming surface of the image forming lens 57 ahead. I have.

The operation of the autofocus optical system 18 will be described with reference to FIG. The light from the lamp 55 is emitted as a point light source by the pinhole 53, and the light for focusing from the point light source becomes a parallel light beam via the condenser lens 52. At this time, the knife edge 56 blocks a semicircle of the circular cross section of the parallel light beam. The light beam of the transmitted semicircle is reflected by the half mirror 51 and travels to the dichroic mirror 15. The light reflected by the dichroic mirror 15 is incident on the sample surface 1 via the objective lens 2, forms an image of the point light source 53, and is reflected. The reflected light beam of the semicircle passes through the semicircular region opposite to the light beam that has passed at the time of incidence, passes through the objective lens 2, and passes through the dichroic mirror 1
5 and is reflected by the dichroic mirror 15 and passes through the half mirror 51 and the imaging lens 57 in this order.
An image is formed on the screen 58.

In the above, when the sample 1 is at the in-focus position, the screen and the imaging lens 5 are placed on the screen 58.
Since the reflected light from the sample 1 forms an image on the intersection with the optical axis of the optical system including the light path 7, the intensity distribution of the received light on the screen 58 has the optical axis intersection as shown as the intensity distribution 58-a. It is distributed almost symmetrically around the center. However, sample 1
For example, a position 1-farther from the objective lens 2 than the in-focus position
a, the screen 5 of the reflected light from the sample 1
The image on 8 has a distribution eccentric to the lower half in the figure from the optical axis intersection, as shown as the intensity distribution 58-b. By measuring this amount of eccentricity, it is possible to detect a deviation from the in-focus position, and by controlling such deviation to minimize it, the surface of the sample 1 can be set to the in-focus position. In this operation, a controller (not shown) that drives the base 40 in the vertical direction in the figure by a controller (not shown) that detects the intensity distribution of the received light on the screen 58 and receives and controls the detection signal. May be driven to perform the processing automatically. That is, auto focus. When the autofocus optical system 18 is provided in this way, even if the focal position slightly changes due to the manufacturing tolerance of the switched variable magnification relay optical system, the focal position can be automatically adjusted. There is no need to adjust.

As described above, according to the embodiment of the present invention, the objective lens is shared, and the relay optical system is provided next to the objective lens, and the magnification is changed by the relay optical system. In the relay optical system, the magnification is applied to the image, and the influence of the eccentricity of the optical axis in the relay optical system is observed in a state where the magnification is hardly applied. Therefore, the manufacturing becomes easier as compared with the revolver.

Further, the relay optical system comprises two lens groups, a first lens group and a second lens group. The front focal point of the first lens group is arranged so as to coincide with the exit pupil of the objective lens.
The front focal point of the second lens group is changed between the relay optical system from the pupil of the objective lens to the pupil conjugate plane by using a relay optical system that matches the rear focal point of the first relay lens group. If the magnification is multiplied, the eccentricity in the relay optical system occurs only on the pupil plane, so that the image does not shift. That is, a light beam emitted from one point on the sample surface is condensed by the objective lens to become a parallel light beam, enters the first lens group of the relay optical system, and forms an image on an intermediate image forming surface. The light beam formed on the intermediate image forming surface spreads again, is condensed by the second lens group of the relay optical system, becomes a parallel light beam, and forms an image on the image surface via the image forming lens. The relay optical system for changing the magnification is placed between the plane where the parallel light flux enters and the plane where the parallel light flux exits, and if the parallel light flux is collected at one point to form an image with the imaging lens Even if the parallel light beams are shifted laterally, there is no change in the focused position.

As described above, according to the embodiment of the present invention, since the image does not shift even when the magnification is changed, the object to be observed is moved to the center of the visual field when the observation is performed with the magnification changed. Observation can be performed efficiently without the need. Further, since the objective lens is not switched, the focus does not shift. In particular, even when the autofocus mechanism is attached, the autofocus function can be activated regardless of the observation magnification by attaching it to the sample side from the variable power relay optical system, so that observation can always be performed with high precision focusing. it can. For this reason, even if the magnification is changed, the focus position adjustment is not performed again, so that the observation can be performed efficiently.

[0029]

As described above, according to the present invention, since the imaging lens system is fixed relative to the objective lens system, the observation position of the microscope is not easily shifted, and a plurality of microscopes having different magnifications are provided. And a switching mechanism for switching between them, it is possible to change the magnification of the microscope, and it is possible to provide a variable magnification microscope in which the observation position does not easily shift even when the magnification is changed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a microscope according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a mechanism for compensating an image shift in the embodiment of FIG. 1;

FIG. 3 is a schematic sectional view showing a microscope according to a second embodiment of the present invention.

FIG. 4 is a schematic side view showing a zoom mechanism of a conventional finite microscope.

FIG. 5 is a schematic explanatory diagram for explaining image shift due to zooming of a conventional infinity microscope.

FIG. 6 is a schematic explanatory view showing an example of an autofocus optical system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sample 2 objective lens 3 first lens group 4 intermediate image plane 5 second lens group 6 imaging lens 7 imaging plane 8 eyepiece 9 observer's naked eye 10, 10a lens barrel 11 turret 12 motor 14 aperture stop 15 Dichroic mirror 16, 17 Telecentric relay optical system 18 Autofocus optical system 23, 23a First lens group 24, 24a Intermediate image plane 25, 25a Second lens group 41, 41a Variable power relay optical system 42, 42a Variable power Relay optics

Claims (3)

[Claims] An objective lens system for condensing light from a sample surface; and forming an image of a light beam condensed by the objective lens system.
An imaging lens system fixed relative to the objective lens system; a plurality of relay optical systems having different magnifications for relaying a light beam condensed by the objective lens system to the imaging lens system; A switching mechanism for switching the plurality of relay optical systems to each other; the plurality of relay optical systems each including a first lens group and a second lens group; A front focus is substantially coincident with a pupil conjugate plane of the objective lens system, and a front focus of the second lens group is substantially coincident with a rear focus of the first lens group. ;microscope. 2. The microscope according to claim 1, wherein an aperture limiting stop is arranged on a pupil conjugate plane closer to the sample surface than the first lens group. 3. A branch system for branching light from the sample surface into an optical path between the sample surface and the relay optical system, and an object of the sample surface and the objective lens system via the branch system. The microscope according to claim 1, further comprising an autofocus optical system that detects a state of alignment with the surface.