Microscope

A microscope includes an illumination system, a stage, and an objective lens that forms an image of a specimen. The stage includes a fixed member whose position and inclination are fixed, a specimen holding member at least one of whose position and inclination is changeable, and a supporting member that supports the specimen holding member. A connection between the supporting member and the specimen holding member and a connection between the supporting member and the fixed member reside near sides of the specimen holding member. The microscope further includes an actuator that changes at least one of the position and the inclination of the specimen holding member with respect to the fixed member, and a buffer mechanism that suppresses transmission of any changes in the inclination of the specimen holding member to the actuator. The actuator and the specimen holding member are connected with the buffer mechanism interposed therebetween.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a microscope used in observing an image of a specimen.

2. Description of the Related Art

It is known that doctors often diagnose diseases on the basis of image data on specimens (samples such as cells or tissues of the body) that is acquired through digital microscopes. Doctors are required to make diagnoses correctly and quickly. Hence, image data to be acquired through digital microscopes needs to be easy to make diagnoses. Furthermore, such image data needs to be quickly acquirable.

When the angle of view of a microscope defined by an objective lens is increased, the area of an image to be acquired at a time increases. This enables quick acquisition of image data but makes it difficult to acquire an image that is in focus at every point of the area defined by that angle of view. This is because each specimen is not flat and has undulations. Hence, the focal plane (a plane at the focal point) of the objective lens does not necessarily conform to the surface of the specimen to be observed.

Accordingly, a method may be employed in which a stage on which a specimen is to be placed is moved on the basis of measured undulations of the specimen and such that the focal plane of the objective lens conforms to the surface of the specimen, whereby at least one of the position and the inclination of the specimen with respect to the objective lens is changed.

Instead of a stage on which a specimen is to be placed, a parallel link mechanism is disclosed by Japanese Patent Laid-Open No. 2002-131605 in which an optical element, which is an object to be moved, is movable with respect to six axes.

The stage of a digital microscope is provided in a very narrow space between an illumination system that illuminates a specimen and an objective lens provided across the specimen from the illumination system. Therefore, even if the parallel link mechanism disclosed by Japanese Patent Laid-Open No. 2002-131605 is applied to the stage of a digital microscope, it is difficult to move the stage through a desired stroke in such a narrow space.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a microscope including a stage that is thin enough to be provided in a space between an illumination system and an objective lens and is movable through a desired stroke.

According to an aspect of the present invention, there is provided a microscope including an illumination system that illuminates a specimen, a stage on which the specimen is to be placed, and an objective lens that forms an image of the specimen illuminated by the illumination system. The stage includes a fixed member whose position and inclination with respect to the objective lens are fixed, a specimen holding member at least one of whose position and inclination with respect to the fixed member is changeable, and a supporting member that supports the specimen holding member with respect to the fixed member. A connection between the supporting member and the specimen holding member and a connection between the supporting member and the fixed member reside near sides of the specimen holding member. The microscope further includes an actuator that drives the specimen holding member such that at least one of the position and the inclination of the specimen holding member with respect to the fixed member is changed, and a buffer mechanism that suppresses transmission of any changes in the inclination of the specimen holding member that may occur with the driving by the actuator to the actuator. The actuator and the specimen holding member are connected to each other with the buffer mechanism interposed therebetween.

DESCRIPTION OF THE EMBODIMENTS

A general embodiment of the present invention will now be described with reference to the attached drawings.FIG. 1is a schematic diagram of a digital microscope according to the general embodiment.

Referring toFIG. 1, a preparation101includes a glass slide having a specimen (sample) pasted thereon with a cover slip provided over the specimen. The preparation101, i.e., the specimen, is placed on a stage301. The specimen is illuminated by an illumination system302. Light from the illumination system302is transmitted through the specimen and enters an objective lens303, where an image of the specimen is formed. An image pickup device304is supported by an image-pickup-device-supporting plate305.

The stage301includes a driving mechanism that meets the following needs:(1) To remove the preparation101from below the objective lens303;(2) To move the preparation101into an area defined by the angle of view of the objective lens303; and(3) To adjust the focus as optimally as possible over the entirety of the area defined by the angle of view of the objective lens303.

Needs (1) and (2) are met by a moving mechanism that moves the preparation101in a plane (XY plane) perpendicular to the optical axis (Z axis) of the objective lens303. Need (3) is met by a combination of a moving mechanism that moves the preparation101in the optical-axis direction (Z-axis direction) of the objective lens303and a rotating mechanism that rotates the preparation101about two axes (X and Y axes) that are perpendicular to the optical axis. To meet Need (3), a specimen moving stage108moves the preparation101in the optical-axis direction of the objective lens303and rotates the preparation101about the two axes perpendicular to the optical axis. The mechanism that meets Needs (1) and (2) may be any of known stage moving mechanisms, and detailed description thereof is therefore omitted herein. The stage301includes such a moving mechanism that moves the preparation101in the XY plane.

To adjust the focus over the entirety of an area defined by the angle of view, the stage301including the specimen moving stage108is driven such that the focal plane (a plane at the focal point) of the objective lens303conforms to the surface of the specimen to be observed. For example, the shape of the surface of the preparation101and the thickness of the cover slip are measured prior to actual imaging, a plane obtained by subtracting the thickness of the cover slip from the shape of the surface of the preparation101is assumed to be the surface of the specimen to be observed, and the stage301including the specimen moving stage108is driven such that the surface of the specimen to be observed conforms to the focal plane of the objective lens303. The surface of the specimen to be observed may be assumed to be a surface for which the root-mean-square (rms) representing a shape obtained by subtracting the shape of the surface of the preparation101from a reference surface is minimized.

The preparation101may be brought into focus manually or by a computer on the basis of an actual image of the preparation101acquired through the objective lens303and the image pickup device304.

To obtain an image having a high resolution, an objective lens having a high numerical aperture (NA) is necessary. In addition, an illumination system having a relatively high NA, not as high as that of the objective lens, is necessary. To minimize the sizes of an objective lens and an illumination system each having a high NA, the distances from the two to the specimen need to be minimized. In the general embodiment, for such reasons that are specific to microscopes, the specimen moving stage108is employed as a stage that is thin enough to be provided in a narrow space between the illumination system302and the objective lens303.

The specimen moving stage108will now be described in detail in accordance with several exemplary embodiments.

First Exemplary Embodiment

FIG. 2is a side view of the specimen moving stage108.FIG. 3is a top view of the specimen moving stage108.

Referring toFIGS. 2 and 3, the preparation101is placed on a specimen holding member102. The specimen holding member102is connected to supporting members104via connecting members103included in the specimen holding member102. The supporting members104are connected to projections105included in a specimen-moving-stage base (hereinafter simply referred to as base)106. The projections105may be integral portions of the base106. The projections105and the base106may be formed together in a mold. Actuators107are provided on the base106.

The base106is a fixed member whose position and inclination with respect to the objective lens303are fixed. At least one of the position and the inclination of the specimen holding member102with respect to the base106and thus with respect to the objective lens303is changeable by using the actuators107provided on the base106.

As illustrated inFIGS. 2 and 3, the supporting members104are each a long bar-like member. The supporting members104are stiff in the longitudinal direction thereof and are flexible (relative to the stiffness in the longitudinal direction) in a direction perpendicular to the longitudinal direction thereof. That is, the supporting members104has a lower stiffness in the direction orthogonal to the longitudinal direction thereof than in the longitudinal direction thereof. As illustrated inFIG. 3, three supporting members104are provided at regular angular intervals around the specimen holding member102. Hence, the specimen holding member102is easy to move along three axes, specifically, easy to move along the optical axis and easy to rotate about two axes that are perpendicular to the optical axis, but is difficult to move along other axes (difficult to rotate about the optical axis and difficult to move along the two axes that are perpendicular to the optical axis).

The supporting members104may each have either a round cross section or a rectangular cross section. In a case where any lines for supplying electricity and/or sucking and exhausting air are necessary so as to hold the preparation101, the supporting members104may be hollow members through which those lines extend. Thus, the configuration of the microscope is simplified.

In the first exemplary embodiment, the connections between the specimen holding member102(the connecting members103included in the specimen holding member102) and the supporting members104and the connections between the base106(the projections105included in the base106) and the supporting members104reside near corresponding ones of the sides of the specimen holding member102as illustrated inFIG. 3. Since the driving mechanism is made up of pieces that are provided near corresponding ones of the sides of the specimen holding member102, which is the object to be driven, the specimen is movable through a desired stroke even in a narrow space defined between the illumination system302and the objective lens303. Such pieces of the driving mechanism do not block light from the illumination system302or light transmitted through the illuminated specimen.

The first exemplary embodiment is characteristic in that each of the actuators107and a corresponding one of the connecting members103included in the specimen holding member102are connected to each other via a buffer mechanism including a leaf spring422and in that a target423for position measurement is provided on each actuator107. The buffer mechanism including the leaf spring422suppresses the transmission of any changes in the inclination of the specimen holding member102that may occur with the driving by the actuator107to the actuator107.

To accurately control the position and the orientation of an object to be driven by an actuator, it is important to measure the current position of the object to be driven. For example, in a case where the current position of an object to be driven is measured externally by using a laser displacement sensor, light from the laser displacement sensor is applied to a target provided on the object to be driven and the reflection from the target is received by a detector, whereby the current position of the object to be driven is calculated. In such a case, if the target inclines, a measurement error may occur. Moreover, even in a case where the object to be driven is intentionally inclined, a measurement error may occur, as described above, if the target is placed directly on the object to be driven.

Accordingly, in the first exemplary embodiment, a buffer mechanism is provided between the specimen holding member102, which is the object to be driven, and the actuator107. The target423is provided at a location where the position of the target423changes uniformly and the inclination of the target423does not tend to change while the specimen holding member102is driven by the actuator107. Specifically, the target423is provided on an L-angle member421that is moved (in the optical-axis direction) by the actuator107. The L-angle member421and the specimen holding member102are connected to each other via the buffer mechanism including the leaf spring422. That is, in the specimen moving stage108, the target423is provided nearer to the actuator107(and the L-angle member421) than the buffer mechanism including the leaf spring422. The position of the target423is measured with a laser displacement sensor424. The point where the actuator107acts on the connecting member103via the L-angle member421, the center of the leaf spring422, and the center of the supporting member104are on a specific line extending in the optical-axis direction.

With the buffer mechanism provided between the specimen holding member102and the actuator107, the center of the supporting member104does not shift even if the specimen holding member102is driven in such a manner as to incline. Hence, the target423moves parallel to the laser displacement sensor424. Consequently, the change in the position of the target423corresponding to the amount of driving by the actuator107is measured accurately, and the driving by the actuator107is controlled with high accuracy on the basis of the measured value.

The displacement sensor used in measuring the current position of the object to be driven is not limited to a laser displacement sensor and may be, for example, an electrostatic-capacitance displacement sensor, an ultrasonic displacement sensor, an air micrometer, an eddy-current displacement sensor, or the like. Instead of such a non-contact displacement sensor, a contact displacement sensor such as an electrical micrometer may alternatively be used, as long as the electrical micrometer does not affect the operation of the actuator107. In that case also, the target of measurement only needs to be provided nearer to the actuator107than the buffer mechanism. In the microscope, the position and the orientation of the driving mechanism with respect to the objective lens303are important. Therefore, the displacement sensor may be provided integrally with the objective lens303.

Second Exemplary Embodiment

FIG. 4is a side view of a specimen moving stage108according to a second exemplary embodiment of the present invention.

In the second exemplary embodiment, a buffer mechanism including an elastic hinge532is provided between each connecting member103and the specimen holding member102. A target533is provided directly on each actuator107. The position of the target533is measured with the laser displacement sensor424provided above the target533.

In the second exemplary embodiment also, the target533does not incline because of the presence of the buffer mechanism including the elastic hinge532even if the specimen holding member102is driven by the actuator107in such a manner as to incline. Therefore, the position of the target533is measured accurately, and the driving by the actuator107is controlled with high accuracy on the basis of the measurement.

Third Exemplary Embodiment

FIG. 5is a side view of a specimen moving stage108according to a third exemplary embodiment of the present invention.

In the third exemplary embodiment, another buffer mechanism including an elastic hinge641is added to the configuration according to the second exemplary embodiment. The elastic hinge641is provided between each supporting member104and a corresponding one of the projections105. The elastic hinge641according to the third exemplary embodiment does not tend to rotate about the longitudinal axis of the supporting member104.

The presence of the elastic hinge641suppresses the rotation of the connecting member103due to the disagreement between the point on which the actuator107acts and the center of the supporting member104. Therefore, the position of the target533is measured more accurately, and the driving by the actuator107is controlled with higher accuracy on the basis of the measurement.

Modifications

Modifications of the first to third exemplary embodiments will be described briefly.

While the base106has six projections105in each of the exemplary embodiments, the base106may have three projections105. Specifically, each supporting member104may be provided with one projection105.

The supporting member104is not necessarily a linear member.

The actuator107may be electrically operated or manually operated. For example, the actuator107may be a manually operated lead screw, a manually operated ball screw, or a manually operated wedge mechanism.

The leaf spring or the elastic hinge that is taken as an exemplary buffer mechanism in each of the exemplary embodiments may be replaced with a stretchable mechanism having a ring shape or a rectangular ring shape and in which the stiffness in a specific direction is different from the stiffness in another direction.

This application claims the benefit of Japanese Patent Application No. 2011-287919 filed Dec. 28, 2011, which is hereby incorporated by reference herein in its entirety.