JPH0695001A - Microscopic device - Google Patents

Abstract

PURPOSE:To observe and photograph the image of wide visual field of a sample surface in addition to a conventional microscopic image and to perform focusing on the image of wide visual field while keeping Koehler illumination by simple constitution. CONSTITUTION:This device is provided with a means for positioning a 1st objective lens 15 so as to be able to retreat from the optical path of an image- formation optical system, and a 3rd objective lens 5 having a longer focal distance than the lens 15, consisting of three lens groups A to C being positive, negative and positive, and guiding light from a 2nd surface to be examined SP' at a position different from a surface to be examined to which illuminating light is guided by the 1st objective lens 15 when the lens 15 is retreated from the optical path to a 2nd objective lens 7 on the optical path so as to form the image of the 2nd surface to be examined SP' at a specified position. An illumination optical system is constituted to form a light source image at the focusing position of the illumination optical system side of the lens 15 or the lens 5 arranged in the optical path, and the 1st and the 2nd lens groups A and B are integrally moved in an optical axis direction to perform the focusing on the 2nd surface to be examined SP'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epi-illumination inverted microscope capable of wide-field observation of a sample surface to be inspected.

[0002]

2. Description of the Related Art No conventional microscope objective lens has an extremely low magnification objective lens of 1 × or less. Figure 2
An example of a conventional epi-illumination inverted microscope is shown in FIG. This is an example of an infinite system including a first objective lens 15 and a second objective lens 17 as an image forming system.

This microscope includes an illumination optical system for illuminating the lower surface SP (surface to be inspected) of the sample S on the stage 16 and a predetermined position of an eyepiece system or an imaging system by imaging light from the surface to be inspected. And an imaging optical system (objective optical system) for forming an image of the surface to be inspected.

In the illumination optical system, as indicated by the broken line in the figure, the illumination light from the light source 11 is collected by the collector lens 12, and the field lens 13 passes through the half mirror M ₁₁ and the front side of the first objective lens 15. After forming the light source image at the focal position (pupil position) 14, the first objective lens 15 forms a parallel light beam and illuminates the surface SP to be inspected with uniform intensity (Kohler illumination).

On the other hand, in the imaging optical system, as shown by the solid line in the figure, the light reflected from the surface to be inspected is converted into a parallel light flux by the first objective lens 15, and then the half mirror M
₁₁ and enters the second objective lens 17 through the mirror M ₁₂ . Further, the parallel light flux is imaged at a predetermined position by the second objective lens 17, and an image of the surface to be inspected is formed there.

Here, the light beam emitted from the second objective lens 17 is split into two light beams by the light splitting prism 18, one of which is imaged on the observation image plane 20 through the mirror M ₁₂ , and the eyepiece optical system 21 is used. It is observed by an observer through. The other side is the image plane 9
An image is formed on the top and taken with a camera or the like. The first objective lens 15 has both an action as an objective lens in the imaging optical system and a action as a condenser lens in the illumination optical system. The observation optical system is basically composed of an image forming optical system (15, 17) and an eyepiece optical system 21.

[0007]

However, in the conventional microscope apparatus as described above, if it is attempted to realize the objective lens 15 at a magnification of 1 or less, the focal length becomes long and it is difficult to design with the same lens barrel length. Is. Therefore, the conventional microscope apparatus has a problem that it cannot meet the demand for observing and photographing a wider range of sample surfaces.

The present invention solves the above problems, has a simple structure, and can observe and photograph not only an image of a sample in a conventional magnification range but also an image of a wide-field sample with an extremely low magnification, and further, Koehler An object of the present invention is to obtain a microscope apparatus capable of focusing an image of a sample having a wide field of view while maintaining illumination.

[0009]

In order to achieve the above object, in a microscope apparatus according to a first aspect of the present invention, an illumination optical system for illuminating a surface to be inspected and a light from the surface to be inspected are provided. Imaging optics having a first objective lens that condenses and forms a parallel light flux, and a second objective lens that images the parallel light flux that has passed through the first objective lens to form an image of the surface under test at a predetermined position. A microscope apparatus including a system, and an insertion / removal unit that retreatably positions the first objective lens with respect to an optical path of the imaging optical system, and a focal length longer than the first objective lens, When the first objective lens is retracted from the optical path, the light from the second test surface at a position different from the test surface is converted into a parallel light flux, and the parallel light flux is converted into the second objective on the optical path. A first lens which guides the light to a lens and forms an image of the second test surface at the predetermined position; The objective lens is provided, the illumination optical system forms a light source image at a focal position on the illumination optical system side of the first objective lens when the first objective lens is located in the optical path, When the third objective lens is located in the optical path, a light source image is formed at a focus position of the third objective lens on the side of the illumination optical system, and the third objective lens causes the second objective lens to move. The first lens group having a positive refracting power, the second lens group having a negative refracting power, and the third lens group having a positive refracting power are provided in this order from the inspection surface side, and are incident from the first lens group. The first lens group and the second lens group form an afocal system for a parallel light beam, and the second lens group and the third lens group form an afocal system for a parallel light beam incident from the third lens group. Forming a focal system, and moving the first and second lens groups integrally in the optical axis direction. Those constructed as more perform focusing from the second test surface.

According to a second aspect of the present invention, in the microscope apparatus according to the first aspect, the light source is obtained by moving the second and third lens groups integrally in the optical axis direction. The image and the focal position on the illumination optical system side of the third objective lens are made to coincide with each other.

[0011]

The present invention is capable of obtaining an observation image in a wide field of view at an extremely low magnification (1 × or less), which is not possible with a conventional microscope, with the simple structure described above. By moving the second lens group integrally, it is possible to focus on the wide-field observation image while maintaining the Koehler illumination.

First, a parallel system between the first objective lens and the second objective lens, that is, these are configured as an infinite system,
If the focal length of the first objective lens is F ₁ and the focal length of the second objective lens is F ₂ , the magnification of the entire optical system is F ₂ /
Since it becomes F ₁ , the magnification becomes low if the first objective lens is an objective lens having a longer focal length than the second objective lens.
Therefore, in this case, it can be understood that the third objective lens having a longer focal length than the second objective lens may be used instead of the first objective lens. Thus, in principle, when the first objective lens is retracted from the optical path, if the third objective lens having a large focal length is arranged, a wide-field image of the second test surface can be observed and photographed. .

At this time, the illumination optical system is configured to form the light source image at the focal position on the illumination optical system side of the first objective lens or the third objective lens arranged in the optical path. Even if the objective lens is inserted into or removed from the optical path, Koehler illumination can be obtained which constantly illuminates the surface to be inspected with no influence on other optical systems.

Now, while simplifying the structure of the microscope apparatus,
In order to significantly improve the operability at the time of focusing, it is necessary to move the third objective lens and perform the focusing without moving the second surface to be inspected. However, if the third objective lens is simply moved, the front-side focal position of the third objective lens also moves, which deviates from the pupil position where the light source image should be formed in order to obtain Koehler illumination.

Therefore, the third objective lens, which has a longer focal length than the first objective lens, has the first lens group having a positive refractive power and the first lens group having a negative refractive power in order from the second test surface side. It is configured to have two lens groups and a third lens group having a positive refractive power, and the first lens group and the second lens group form an afocal system for the parallel light flux incident from the first lens group. At the same time, the second lens group and the third lens group are configured to form an afocal system with respect to the parallel light flux incident from the third lens group, and the first and second lens groups are integrally fixed in the optical axis direction. By moving to, it is possible to focus on the second surface to be inspected while maintaining the Koehler illumination. The operation of the present invention will be described with reference to FIG.

A third objective lens as used in FIG. 3, the second test surface SP 'side from the positive lens group of the focal length f ₁ in order (first lens group) A, negative focal length f ₂ This is a three-group configuration including a lens group (second lens group) B and a positive lens group (third lens group) C having a focal length f ₃ .

The first lens group A and the second lens group B, and the second lens group B and the third lens group C respectively constitute a Galileo variable power system. In other words, a word and a section indicated by a dotted line ,
The first lens group A and the second lens group B form an afocal system with respect to the parallel light flux incident from the first lens group A,
As shown by the solid line, the second lens group and the third lens group C form an afocal system for the parallel light flux incident from the third lens group C. At this time, the principal point distance between the first lens group A and the second lens group B is f ₁ + f ₂ ,
The principal point distance between the lens unit B and the third lens unit C is f ₂ + f ₃
Is.

In such an optical system, when the first lens group A and the second lens group B are moved integrally on the optical axis, the rear focal position F'moves but the front focal position F changes. Do not move. Therefore, the first lens group A and the second lens group B
Even if focusing is performed on the second surface SP ′ to be inspected by integrally moving and on the optical axis, the front focus position F does not deviate from the pupil position H where the light source image should be formed, and is always Koehler lighting can be obtained. Moreover, since the first lens group A and the second lens group B form a Galileo variable power system, even if these two lens groups are moved together for focusing, the focal length of the third objective lens itself is It doesn't change, so
The observation magnification can be kept constant.

Here, the first lens group A and the second lens group B
The relationship between the moving amount DX ′ of the above and the moving amount DF ′ of the rear focus position F ′ is given by the following expression (1). DF ′ = DX ′ (1-1 / β ′ ² ) (1) Equation β ′ is the magnification of Galileo variable magnification system (combined system of the first lens group A and the second lens group B) β ′ = -f is a ₂ / f _1.

Further, in this system, when the second lens group B and the third lens group C are integrally moved on the optical axis, the rear focal position F'is not moved but the front focal position F is moved. . Therefore, when the light source image position (pupil position) H of the illumination optical system is changed, the second lens group B and the third lens group C are moved integrally on the optical axis, whereby the second surface SP ′ to be inspected.
The front focus position F is changed to the pupil position H while the focus state is maintained.
Can be adjusted to match the Koehler lighting.

At this time, the second lens unit B and the third lens unit C
The relationship between the moving amount DX of the lens and the moving amount DF of the front focus position F is given by the following equation (2). DF = DX (1-1 / β ² ) (2) Equation β is the magnification of the Galileo variable power system (composite system of the second lens group B and the third lens group C) and β = −f ₂ / f is _3.

As described above, according to the present invention, the second group and the third group are provided.
Since the unit is provided with a unit for moving the unit along the optical axis, it becomes possible to perform the focusing operation while always maintaining the Koehler illumination. Furthermore, in the present invention,
By providing a means for moving the second lens group and the third lens group integrally on the optical axis, it is possible to adjust the Koehler illumination of the illumination optical system while maintaining the in-focus state.

[0023]

EXAMPLES Examples of the present invention will be described below. Figure 1
FIG. 4 is a schematic configuration diagram showing an optical system of a microscope apparatus according to an embodiment of the present invention, showing a state in which a first objective lens is retracted from an optical path. In this embodiment, the first objective lens 15
And the light beam transmitting hole member 22 are configured to be interchangeable with respect to the optical path, and a desired low enough to observe the second test surface SP ′ on the sample S mounted on the stage 6 as a wide-field image. The macroscopic objective lens 5 is provided as a third objective lens (having a long focal length) that serves as a magnification. Other configurations are similar to those of the conventional microscope shown in FIG.

In this embodiment, similarly to the conventional apparatus shown in FIG. 2, a portion 16 'corresponding to the sample surface position SP on the stage 16 observed by the first objective lens is
The optical path to the macroscopic objective lens 5 and the second surface to be inspected SP ′ is designed so that the light flux is transmitted, and the optical path to the first objective lens when arranged in the optical path is an extension of the optical path to the first objective lens. is there.

The macroscopic objective lens 5 has a positive refractive power in order from the second surface SP 'to be inspected, and has a first lens group A.
, A second lens unit B having a negative refractive power, and a third lens unit B having a positive refractive power
The first lens group A and the second lens group B form an afocal system with respect to the parallel light flux shown by the dotted line which is incident from the first lens group A, and the third lens group C
The second lens group B and the third lens group C form an afocal system with respect to the parallel light flux shown by the solid line which is incident from the obtained lens group C.

A case of observing the second test surface SP 'on the stage 6 as a wide-field image will be described with reference to FIG. In FIG. 1, the first objective lens 15 is retracted from the optical path,
The light flux transmission hole member 22 is inserted. First, in the illumination optical system, the illumination light L ₂ emitted from the light source 1 passes through the collector lens 2 as shown by the dotted line, and is passed by the field lens 3 via the half mirror M ₁ to the front focus of the macro observation objective lens 5. A light source image is formed at the pupil position 4, which is the position. After that, the light enters the objective lens 5 for macro observation through the mirror M ₂ . The second observation surface SP ′ of the sample S, which is converted into a parallel light flux by the microscopic observation objective lens 5 and is placed on the stage 6 via the mirror M ₃ , is illuminated with uniform intensity as Koehler illumination.

The return light L ₁ from the second surface SP ′ to be inspected is incident on the macro observation objective lens 5 via the mirror M ₃ and is converted into a parallel light flux, as shown by the solid line. Then, the parallel luminous flux becomes and is condensed by the second objective lens 7 via the mirror M ₂ , the half mirror M ₁ and the mirror M ₄ . This condensed light flux is split into two by the light splitting prism 8, one of which forms an image of the second test surface SP ′ on the observation image plane 10 via the mirror M ₅ and the other one of which is the photographic image plane 9 An image of the second test surface SP ′ is formed on the top.

By the way, when the first objective lens is retracted and the macroscopic observation objective lens 5 observes the sample surface SP 'in a wide field of view, the front focus position 4 thereof is the optical path of the first objective lens 15 thereof. The second lens group B and the third lens group are arranged so as to coincide with the front focus position 14 when arranged inside, that is, the light source image in which the illumination section is tilted to the right coincide with the pupil position 4. By moving C and the optical axis on the optical axis as a unit, it is possible to adjust so as to obtain Koehler illumination. At this time, since the second lens unit B and the third lens unit C form a Galileo variable power system, the second lens unit B and the third lens unit B
Even if the lens group C and the lens group C are moved together on the optical axis, the rear focal position does not move, but only the front focal position moves. Therefore, adjustment for Koehler illumination can be performed without affecting the focusing on the sample inspection surface SP ′ on the stage 6.

Further, the first lens group A and the second lens group B are installed so as to move integrally on the optical axis, and by this movement, the focusing operation on the second surface SP 'to be inspected is performed. First
The lens group A and the second lens group B form a Galileo variable magnification system, and when they are integrally moved on the optical axis, the front focus position does not move, but only the rear focus position moves. Therefore, the focusing operation to the second surface SP ′ to be inspected can be performed while maintaining the Koehler illumination without affecting the illumination optical system.

Various means can be used as means for inserting / removing the first objective lens 15 into / from the optical path. For example, it is simple to use a revolver mechanism for switching objective lenses having different magnifications in an ordinary microscope. is there. That is, as shown in FIG. 1, the revolver is provided with the first objective lens 15 and the light beam transmission hole member 22 that allows the light beam to pass therethrough.
These can be switched by rotating the revolver. At this time, it goes without saying that the revolver may be provided with a plurality of first objective lenses having different magnifications. It goes without saying that the stage 6 shown in FIG. 1 may be arranged above the microscope apparatus so as to be in parallel with the stage 16.

[0031]

As described above, according to the present invention,
With a simple structure, it is not only possible to obtain an observation image with a wide field of view at low magnification, which was not possible with conventional microscopes, but also focusing operation with Koehler illumination maintained and Koehler with focusing maintained There is an effect that the lighting can be adjusted.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a microscope apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional microscope apparatus.

FIG. 3 is an explanatory view showing the operation of the present invention.

[Explanation of symbols]

1, 11: light source 2, 12: collector lens 3, 13: field lens 4, 14, H: pupil position 5: objective lens for macro observation of 3 group constitution 15: first objective lens 6, 16: stage SP ': second test surface 7, 17: second objective lens 8 and 18: light splitting prism 9 and 19: photographing image plane 10, 20: observation image plane _{M 2, M 3, M 4} , M 12: mirror M _1, M ₁₁ : Half mirror

Claims (2)

[Claims] 1. An illumination optical system for illuminating a surface to be inspected,
A first for collecting light from the surface to be inspected to form a parallel light flux
A microscope apparatus comprising: an objective lens; and an image forming optical system having a second objective lens for forming an image of the surface to be inspected at a predetermined position by forming an image of a parallel light flux through the first objective lens. When the first objective lens retracts from the optical path, the insertion / removal unit positions the first objective lens to be retractable with respect to the optical path of the image optical system, and has a focal length longer than that of the first objective lens. In addition, the light from the second surface to be inspected at a position different from the surface to be inspected is converted into a parallel light beam, the parallel light beam is guided to the second objective lens, and the second surface to be inspected is placed at the predetermined position. And a third objective lens that forms an image of the first objective lens in the optical path, the illumination optical system is provided at a focal position on the illumination optical system side of the first objective lens. A light source image is formed, and the third objective lens is located in the optical path. At this time, a light source image is formed at a focus position of the third objective lens on the side of the illumination optical system, and the third objective lens sequentially has a positive refractive power of the first objective surface side from the second test surface side. A first lens group, a second lens group having a negative refractive power field, and a third lens group having a positive refractive power, and the first lens group and the first lens group with respect to a parallel light flux incident from the first lens group. The second lens group and the second lens group form an afocal system, and the second lens group and the third lens group form an afocal system with respect to the parallel light flux incident from the third lens group. A microscope apparatus characterized in that focusing is performed on the second surface to be inspected by integrally moving the lens group in the optical axis direction. 2. The light source image and the focus position on the illumination optical system side of the third objective lens are made to coincide by moving the second and third lens groups integrally in the optical axis direction. The microscope apparatus according to claim 1.