JP3039388B2 - Microscope equipped with a first objective lens for extremely low magnification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope, and more particularly to an infinity microscope capable of observing a sample surface to be inspected at a very low magnification in a wide field of view. In the present invention, the extremely low magnification refers to a magnification of about 0.5 to 1.5 times.

[0002]

2. Description of the Related Art Generally, an interchangeable objective lens mounted on a revolver of a microscope has a parfocal length (a distance between a body surface when the objective lens is mounted on the revolver and a stage surface on which a sample is mounted). (The distance along the optical axis between them).

[0003]

Therefore, for example, if an attempt is made to design an extremely low magnification objective lens having a magnification of 1 or less, the required focal length becomes large, and it is difficult to fit the entire length within the same focal length. Have difficulty. As a result, the conventional microscope did not have an extremely low magnification objective lens of 1 × or less.

[0004] Therefore, when observing or photographing a wider area of an image on a sample surface to be inspected, a microscope cannot meet the demand, and an apparatus other than the microscope, such as a stereoscopic microscope or a macro photographic apparatus, can respond. There was only. Therefore, when observing or photographing the details of the sample, a microscope must be used, and when observing or photographing the entire sample, a stereomicroscope or a macro photographic apparatus must be used. As a result, many complicated operations such as positioning of the sample every time the apparatus is changed, and the working efficiency was extremely poor.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a microscope capable of observing or photographing a sample at a plurality of magnification states in an extremely low magnification range.

[0006]

In order to achieve the above object, a microscope according to an aspect of the present invention includes a plurality of first objective lenses that are switchable with respect to an optical path. A revolver configured to be capable of mounting a first objective lens, and a revolver provided at a position where a light flux from the first objective lens located in the optical path among the plurality of first objective lenses is guided to collect the light flux A microscope having a second objective lens for forming a real image of an object by means of a pole having a positive refractive power and being removably provided in an optical path between the first objective lens and the second objective lens. Equipped with an auxiliary lens for low magnification,
The revolver is configured such that an extremely low magnification first objective lens including a first positive lens unit and a second negative lens unit disposed on the image side of the positive lens unit can be mounted. When the objective lens is located in the optical path, the extra low magnification auxiliary lens is located in the optical path and satisfies the following conditions. (1) 1 ≦ (D + L) /fS≦1.5 (2) 50 ≦ L ≦ 200 (3) 12 ≦ | ν1S−ν2S | where D: parfocal length of the microscope, fS: extremely low magnification The focal length of the auxiliary lens, ν1S: Abbe number of the lens element having the largest Abbe number among the lens elements constituting the extra low magnification auxiliary lens, ν2S: Of the lens elements constituting the extra low magnification auxiliary lens, , Abbe number of the lens element having the smallest Abbe number, L: distance from the barrel surface of the objective lens to the lens surface closest to the image of the extra low magnification auxiliary lens.

In a preferred aspect of the present invention, detecting means for outputting a predetermined signal when the extremely low magnification first objective lens is located in the optical path, and disposing the extra low magnification auxiliary lens inside and outside the optical path. A driving unit for selectively moving the control unit, and a control unit for controlling the driving unit to move the extra low magnification auxiliary lens into the optical path based on the predetermined signal from the detection unit. It is composed of

In the microscope according to a preferred aspect of the present invention, the focal length of the first group of the first objective lens for extremely low magnification is f1a, and the first objective lens for extremely low magnification and the extremely low magnification are connected to each other. Where the composite focal length with the auxiliary lens for imaging is fa, and the composite lateral magnification of the first objective lens for ultra low magnification, the auxiliary lens for ultra low magnification and the second objective lens is βa, (4) | βa | ≦ 1.5 (5) The condition of 0.07 ≦ f1a / fa ≦ 0.25 is satisfied.

Further, in the microscope according to a preferred aspect of the present invention, the plurality of first objective lenses include another ultra-low magnification first objective lens having a magnification different from that of the ultra-low magnification first objective lens. The another ultra-low magnification first objective lens includes a positive first group and a negative second group disposed on the image side of the positive lens group, and the another ultra-low magnification first objective lens. Is located in the optical path, the extra low magnification auxiliary lens is configured to be located in the optical path.

In the microscope according to a preferred aspect of the present invention, the composite lateral magnification of the first objective lens for extremely low magnification, the auxiliary lens for extremely low magnification and the second objective lens is βa, When the combined lateral magnification of the first objective lens for low magnification, the auxiliary lens for extremely low magnification, and the second objective lens is βb, (6) 1.25 ≦ | βb | / | βa | ≦ 2.75 It satisfies the following conditions. (7) 0.1 ≦ f1b / fb ≦ 0.5 (8) 0.2 ≦ (t1b + t2b) /D≦0.8, where f1b is the first group of the another ultra-low magnification first objective lens. Focal length, fb: composite focal length of the another extra-low magnification first objective lens and the extra-low magnification auxiliary lens, t1b: lens center of the first group of the another extra-low magnification first objective lens T2b: total value of the lens center thickness of the second group of the another ultra-low magnification first objective lens, D: parfocal length of the microscope.

It is preferable that the extra low magnification auxiliary lens in the present invention has a cemented lens.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first objective lens for ultra-low magnification in a microscope according to the present invention is an objective lens for observing a wide-field image with a microscope, and is characterized by a wide real field of view. The illumination of the microscope is generally Koehler illumination, and since the specimen is telecentricly illuminated, the lens element closest to the specimen (object side) needs to have a lens diameter substantially equal to or larger than the actual field of view. Since the screw diameter of the portion of the objective lens to be mounted on the revolver is fixed, it is necessary to make the diameter of the light beam passing through that position smaller than this screw diameter. Therefore, the first lens unit is provided with a positive refractive power to condense a light beam from a wide field of view.

Further, the lens system of the present invention (the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification) is characterized in that since the magnification is extremely low, the combined focal length is long. Here, when viewed from the side opposite to the sample surface (the second objective lens side),
In the present invention, the auxiliary lens for extremely low magnification of the positive refractive power and the second group of the negative refractive power are arranged in this order, and the telephoto ratio is applied to the positive refractive power group and the negative refractive power group. With this configuration, the overall length can be made shorter than the focal length.

For the above reasons, the lens system of the present invention comprises, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, and an auxiliary lens having a positive refractive power. ing. The first and second groups are configured as a very low magnification first objective lens mounted on a revolver, and the very low magnification auxiliary lens located on the image side is composed of a first objective lens and a second objective lens. Is configured to be freely insertable into and removable from the optical path between the first objective lens and the first objective lens for extremely low magnification.

Next, each conditional expression will be described. The microscope according to the present invention satisfies the following conditions (1) to (3). (1) 1 ≦ (D + L) /fS≦1.5 (2) 50 ≦ L ≦ 200 (3) 12 ≦ | ν1S−ν2S | where D: parfocal length of the microscope, fS: extremely low magnification The focal length of the auxiliary lens, ν1S: Abbe number of the lens element having the largest Abbe number among the lens elements constituting the extra low magnification auxiliary lens, ν2S: Of the lens elements constituting the extra low magnification auxiliary lens, , Abbe number of the lens element having the smallest Abbe number, L: distance from the barrel surface of the objective lens to the lens surface closest to the image of the extra low magnification auxiliary lens.

The condition (1) defines the relationship between the position of the extra low magnification auxiliary lens and its focal length, and affects the working distance and the parfocal length. If the upper limit of the condition (1) is exceeded, the front (object side) focal position of the extra-low magnification auxiliary lens will be behind the body-mounted surface, so that the extra-low magnification first objective lens protrudes from the same focal length. Would be. If the lower limit of the condition (1) is exceeded, the front focal position of the extra-low magnification auxiliary lens comes forward, so that the first objective lens of the extra-low magnification first objective lens.
Since the group and the second group are arranged closer to the object side, the working distance becomes shorter.

Here, the first objective lens for extremely low magnification has a small magnification and a small NA, and therefore has a large depth of focus. Therefore, in order to secure a safe working distance and to fit the lens system within the parfocal length with a margin, it is more preferable that the upper limit is 1.45 and the lower limit is 1.2. Condition (2) is:
It determines the position of the extra low magnification auxiliary lens, and is a factor related to the shape of the microscope. In general, microscopes
The revolver is attached to the arm that is the main body, and the objective lens is mounted below the revolver. Then, a lens barrel is mounted on the arm to observe or photograph.

If the upper limit of the condition (2) is exceeded, the extra-low magnification auxiliary lens will enter the lens barrel.
Since the objective lens is further disposed after that, the lens diameter of the second objective lens becomes large, and the lens barrel becomes large, which makes it difficult to use. If the lower limit of the condition (2) is exceeded, the overall length becomes short, so that it becomes necessary to apply a strong telephoto ratio, and it becomes difficult to correct various aberrations in a well-balanced manner. If an auxiliary lens for extremely low magnification is to be housed in an arm with an appropriate telephoto ratio that facilitates aberration correction, the upper limit is more preferably set to 150 and the lower limit is set to 110.

Condition (3) defines the difference in Abbe numbers of a plurality of lens elements in the extra low magnification auxiliary lens, and relates to axial chromatic aberration. If the lower limit of condition (3) is exceeded,
Correction of axial chromatic aberration is insufficient. More preferably, the lower limit is set to 15. Further, the first objective lens for ultra low magnification mounted on the microscope according to the present invention is the first objective lens for ultra low magnification.
The focal length of the first group of objective lenses is f1a, the combined focal length of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification is fa, and the first objective lens for extremely low magnification, extremely low magnification When the combined lateral magnification of the auxiliary lens and the second objective lens is βa, it is preferable to satisfy the following condition: (4) | βa | ≦ 1.5 (5) 0.07 ≦ f1a / fa ≦ 0.25 .

Condition (4) is a condition that means that the very low magnification first objective lens is in a very low magnification state, and is a prerequisite of condition (5). Condition (5) defines the focal length of the first group of the first objective lens for extremely low magnification.
The focal length of the first group affects chromatic aberration of magnification and Petzval sum. Exceeding the upper limit of the condition (5) is not preferable because the Petzval sum becomes large and the plan property (flatness of the image plane) is remarkably deteriorated. When the value goes below the lower limit of the condition (5), the refractive power becomes strong. Therefore, the radius of curvature of the lens element constituting the first lens unit also becomes tight, whereby the change in chromatic aberration of magnification when the image height increases is sharp. This is undesirable because it is difficult to correct various aberrations of the lens system in a well-balanced manner. More preferably, the upper limit is 0.2 and the lower limit is 0.1.

In the microscope according to the present invention, the plurality of first objective lenses include another ultra-low magnification first objective lens having a magnification different from that of the ultra-low magnification first objective lens. The very low magnification first objective lens includes a first positive lens group and a negative second lens group disposed on the image side of the positive lens group, and another extra low magnification first objective lens is located in the optical path. In this case, it is preferable that the extra low magnification auxiliary lens is located in the optical path. At this time, the combined magnification of the first objective lens for extremely low magnification, the auxiliary lens for extremely low magnification, and the second objective lens is βa, and another first objective lens for extremely low magnification, an extremely low magnification auxiliary lens, and the second objective lens. When the combined magnification of the objective lens is βb, it is preferable that (6) satisfy 1.25 ≦ | βb | / | βa | ≦ 2.75, and further satisfy the following condition. (7) 0.1 ≦ f1b / fb ≦ 0.5 (8) 0.2 ≦ (t1b + t2b) /D≦0.8, where f1b is the first group of the another ultra-low magnification first objective lens. Focal length, fb: composite focal length of the another extra-low magnification first objective lens and the extra-low magnification auxiliary lens, t1b: lens center of the first group of the another extra-low magnification first objective lens T2b: total value of the lens center thickness of the second group of the another ultra-low magnification first objective lens, D: parfocal length of the microscope.

Condition (7) defines the focal length of the first group in another ultra-low magnification first objective lens.
The focal length of the group also affects chromatic aberration of magnification and Petzval sum. The condition (7) is based on the premise that the magnification relationship between the very low magnification first objective lens and another very low magnification first objective lens satisfies the above condition (6). Here, when the value exceeds the upper limit of the condition (7), the Petzval sum becomes large and the plan property is remarkably deteriorated.
When the value goes below the lower limit of the condition (7), the refractive power becomes strong, so that the radius of curvature becomes sharp. As a result, the change in chromatic aberration of magnification when the image height increases increases sharply, and the various aberrations of the lens system are balanced. It is not preferable because it is difficult to correct. More preferably, the upper limit is 0.3 and the lower limit is 0.15.

The condition (8) defines the range of the total thickness of the center of the lens of another first objective lens for extremely low magnification, and relates to the object-image distance and the Petzval sum. Exceeding the upper limit of the condition (8) is not preferable because the Petzval sum becomes large and the plan property is remarkably deteriorated. If the lower limit of the condition (8) is exceeded, the overall length becomes short, which makes it difficult to observe the principle of keeping the distance between objects and images unfavorable. More preferably, the upper limit is set to 0.75 and the lower limit is set to 0.25.

As described above, the first objective lens for extremely low magnification and another first objective lens for extremely low magnification are provided with the above-mentioned conditions (4) to (8).
Is satisfied, it is possible to share a very low magnification auxiliary lens used in combination with these. Accordingly, even if a plurality of first objective lenses for ultra-low magnification having different magnifications in the extremely low magnification region are used for observation under a plurality of magnification states in the extremely low magnification region, each of the respective ultra-low magnifications is used. It is not necessary to use a plurality of extra-low magnification auxiliary lenses corresponding to the first objective lens for low magnification. For this reason, the cost of the microscope can be reduced, and when the auxiliary lens for extra low magnification is manually switched, the user may mistakenly combine the first objective lens for extra low magnification with the auxiliary lens for extra low magnification. There is an advantage that there is no.

When the plurality of ultra-low magnification first objective lenses are not used, that is, when only one ultra-low magnification first objective lens is used, the above conditions (7) and (8) are satisfied. The following condition (9) is presupposed instead of the condition (6). (9) | βb | ≦ 1.5, where βb is a composite lateral magnification of the first objective lens for extremely low magnification, the auxiliary lens for extremely low magnification, and the second objective lens.

Next, a microscope according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a configuration of a microscope according to an embodiment of the present invention. FIG. 1A shows a first objective lens for extremely low magnification and an auxiliary lens for extremely low magnification in an optical path. 1B shows a state in which a normal first objective lens is arranged in an optical path.

In FIG. 1A, a revolver 20 configured to be capable of mounting a plurality of first objective lenses 10 and 11 includes:
It is attached to a mirror base 21 which is a microscope main body, and a lens barrel 22 is mounted above the mirror base. An eyepiece unit 23 for visually observing the image of the sample is attached to the lens barrel 22. The mirror base 21 is provided with a stage 30 on which a sample is placed and an illumination unit 40 for supplying illumination light. The illumination light from the illumination unit 40 is
The specimen on the stage 30 is transmitted and illuminated via 1.

Here, in the state of FIG. 1A, the very low magnification first objective lens 10 attached to the revolver 20
Position in the optical path (the optical axis of the very low magnification first objective lens is the optical axis A
x), and at this time, the extra low magnification auxiliary lens S is also positioned in the optical path (the optical axis of the extra low magnification auxiliary lens S coincides with the optical axis Ax). The extra low magnification auxiliary lens S is attached to a moving unit 50 for selectively moving the extra low magnification auxiliary lens S to a position in the optical path and a position outside the optical path.

As shown in FIG. 1 (b), when observing a sample at a normal magnification, the revolver 20 is rotated and the first objective lens 11 of a normal magnification attached to the revolver 20 is rotated. In the optical path (the first objective lens 11
Optical axis coincides with the optical axis Ax), and the moving unit 50
Is moved to a position outside the optical path. As a result, light from the illuminated sample is transmitted to the first objective lens 11 and the second lens
An enlarged image of the specimen is formed via the objective lens.

Returning to FIG. 1 (a), when observing the specimen at an extremely low magnification (for example, about -0.5 to -1.5 times), the revolver 20 is rotated and The very low magnification first objective lens 10 attached to the revolver 20 is located in the optical path, and the extra low magnification auxiliary lens S attached to the moving unit 50 is located in the optical path. Thus, the illuminated light from the sample forms an image of the sample at an extremely low magnification through the first objective lens 10 for extremely low magnification, the auxiliary lens S for extremely low magnification, and the second objective lens (not shown). FIG.
In (a), although not shown, another ultra-low magnification first objective lens having an ultra-low magnification different from that of the ultra-low magnification first objective lens 10 is attached to the revolver 20. When the specimen is observed using the first objective lens for ultra-low magnification, the extra-low magnification auxiliary lens S is located in the optical path.

Next, referring to FIG.
And the moving unit 50 will be described in detail. FIG. 2 shows FIG.
It is a figure which shows the principal part of the microscope shown to (a), (b). 2, the revolver 20 is configured to be rotatable around a rotation axis 20Ax oblique to the optical axis Ax, and a plurality of openings 20a are provided at positions equidistant from the rotation axis 20Ax. . A female screw is formed in the opening 20a, and is configured to be screwable with a male screw formed in a lens barrel of the first objective lens 10 for extremely low magnification. Here, a portion which is flush with the opening 20a of the revolver 20 becomes a body-attached surface Z of the first objective lens 10 for extremely low magnification.

The extra low magnification auxiliary lens S is housed in a lens frame 51, and this lens frame 51 is
2 is provided movably in the left-right direction in the figure.
Further, a rod 53 is attached to the lens frame 51, and the observer can selectively move the extra low magnification auxiliary lens S in the lens frame 51 to a position inside or outside the optical path via the rod 53. it can. Note that the outer frame 52 is
It is fixed to.

Also, as shown in FIG.
Sensor 6 for detecting whether the objective lens is located in the optical path
1 is provided on the revolver 20, an actuator 62 for selectively moving the extra low magnification auxiliary lens S to a position inside or outside the optical path is provided on the moving unit 50, and a controller 63 for driving the actuator 62 based on an output from the sensor 61 is provided. May be provided. At this time, for example, the sensor 61 outputs a predetermined signal when the very low magnification first objective lens is located in the optical path, and the controller 63 receives the signal from the sensor 61 and outputs the extra low magnification auxiliary lens. The actuator 62 is driven so that the lens S is located in the optical path. When a first objective lens other than the first objective lens for extremely low magnification is located in the optical path, the sensor 61 outputs a signal different from the above-mentioned signal, and the controller 63 outputs an extremely low magnification in accordance with this signal. The actuator is driven to move the auxiliary lens S for use to a position outside the optical path. With this configuration, the auxiliary lens for extremely low magnification can be automatically inserted and removed from the optical path in accordance with the switching of the first objective lens.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Numerical embodiments will be described below with reference to the drawings. 4 to 11 are optical path diagrams of Examples 1 to 4, FIGS. 12 to 19 are diagrams of various aberrations of Examples 1 to 4, and FIG. 20 is a lens configuration diagram of the second objective lens. [Embodiment 1] FIGS. 4 and 5 show the very low magnification first embodiment of the first embodiment.
FIG. 5 is a lens configuration diagram showing an objective lens and an auxiliary lens S for extremely low magnification, and a first objective lens for extremely low magnification in FIG.
The first objective lens for extremely low magnification shown in FIG. 5 has a magnification of -1.

The very low magnification first objective lens shown in FIG. 4 and the very low magnification first objective lens shown in FIG.
Side) in order from the first group 1 having a positive refractive power and the second group having a negative refractive power.
And group 2. On the image side of the first objective lens for ultra-low magnification, an auxiliary lens S for ultra-low magnification having a positive refractive power is arranged. In the very low magnification first objective lens shown in FIG. 4, the first group 1 includes, in order from the object side, a meniscus positive lens having a convex surface facing the object side, and a cemented lens including a biconvex lens and a biconcave lens. Is done. Also,
The second unit 2 includes a cemented lens including a biconcave lens having a strong concave surface facing the image side and a meniscus positive lens having a convex surface facing the object side.

In the very low magnification first objective lens shown in FIG.
The first unit 1 includes, in order from the object side, a meniscus positive lens having a concave surface facing the object side, and a cemented lens including a biconvex lens and a biconcave lens. The second unit 2 includes a biconcave negative lens having a strong concave surface facing the image side. The extra low magnification auxiliary lens S of the first embodiment includes a cemented lens including a positive meniscus lens having a convex surface facing the image side and a negative meniscus lens having a convex surface facing the image side.

Tables 1 and 2 below show lens data of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 1. Here, Table 1 shows lens data of an extremely low magnification objective lens and a very low magnification auxiliary lens with a magnification of -0.5, and Table 2 shows an extremely low magnification first objective lens with a magnification of -1. It is lens data of an extra low magnification auxiliary lens. In each table, βa is the lateral magnification when the optical system of Table 1 (the first objective lens for ultra-low magnification and the auxiliary lens for ultra-low magnification) is combined with a second objective lens described later, and βb is the optical system of Table 2. Lateral magnification when the first (low-magnification first objective lens and very-low-magnification auxiliary lens) are combined with a second objective lens described later; A. Is the numerical aperture on the object side of the first objective lens for extremely low magnification, and the actual field of view is the diameter of the actual field of view of the first objective lens for extremely low magnification, the entrance pupil distance and the object distance are all on the first surface (most object). The total length is the distance from the sample surface (object surface) to the most image-side lens surface of the extra low magnification auxiliary lens S, and the focal length is the objective lens. The distance along the optical axis between the body surface Z and the sample surface O when mounted on the revolver, f
a is the composite focal length of the first objective lens for ultra low magnification and the auxiliary lens for ultra low magnification in Table 1, and fb is the composite focal length of the first objective lens for ultra low magnification and the auxiliary lens for ultra low magnification in Table 2. Is shown. In Tables 1 and 2, the leftmost numeral is the surface number, r is the radius of curvature of each lens surface, d is the lens surface interval,
nd represents the refractive index for the d-line, and νd represents the Abbe number for the d-line. In addition, the surface number 9 in Table 1
The surface numbers 8-10 in -11 and Table 2 correspond to the lens data of the extra-low magnification auxiliary lens commonly used in the ultra-low magnification first objective lenses having different magnifications in Tables 1 and 2. .

[0038]

[Table 1] βa = -0.5x, NA = 0.025, real field of view = 50, entrance pupil = 物体 object distance = 7.8, total length = 184, parfocal length = 60, fa = 399.5 plane rd nd νd 1 49.754 8 1.74400 45.0 2 239.108 0.2 1 3 56.522 8.5 1.65844 50.84 4 -230.48 3 1.68893 31.08 5 81.358 24 1 6 -59.222 2 1.651599 58.5 7 13.936 4.6 1.804581 25.5 8 18.297 119.9 1 9 -230.781 4 1.622801 57.03 10 -31.106 2 1.749501 35.19 11 -54.724

[0039]

[Table 2] βb = −1 ×, NA = 0.05, real field of view φ = 25, entrance pupil = ∞, object distance = 23.2, total length = 184, parfocal distance = 60, fb = 201.3 plane rd nd νd 1 -99.025 17 1.787971 47.47 2 -63.626 0.2 1 3 29.009 16 1.65844 50.84 4 -41.406 2.5 1.749501 35.19 5 307.446 6.3 1 6 -148.037 2.4 1.651599 58.5 7 20.35 110.4 1 8 -230.781 4 1.622801 57.03 9 -31.106 2 1.749501 35.19 10 -54.724 [Example] 2] FIGS. 6 and 7 show the very low magnification first embodiment of the second embodiment.
FIG. 7 is a lens configuration diagram showing an objective lens and an auxiliary lens S for extremely low magnification, and a first objective lens for extremely low magnification in FIG.
The first objective lens for extremely low magnification shown in FIG. 7 has a magnification of -1.

The very low magnification first objective lens shown in FIG. 6 and the very low magnification first objective lens shown in FIG.
Side) in order from the first group 1 having a positive refractive power and the second group having a negative refractive power.
And group 2. On the image side of the first objective lens for ultra-low magnification, an auxiliary lens S for ultra-low magnification having a positive refractive power is arranged. In the very low magnification first objective lens shown in FIG. 6, the first group 1 includes, in order from the object side, a meniscus positive lens having a convex surface facing the object side, and a cemented lens including a biconvex lens and a biconcave lens. Is done. Also,
The second unit 2 includes a cemented lens including a biconcave lens having a strong concave surface facing the image side and a meniscus positive lens having a convex surface facing the object side.

In the very low magnification first objective lens shown in FIG.
The first unit 1 includes, in order from the object side, a positive meniscus lens having a concave surface facing the object side, and a cemented lens composed of a biconvex lens and a negative meniscus lens having a concave surface facing the object side. The second unit 2 includes a biconcave negative lens having a strong concave surface facing the image side. The extra low magnification auxiliary lens S of Example 2 is composed of a cemented lens composed of a positive meniscus lens having a convex surface facing the image side and a negative meniscus lens having a convex surface facing the image side.

Tables 3 and 4 below show lens data of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 2. Here, Table 3 shows the lens data of the ultra-low magnification objective lens and the extra low magnification auxiliary lens having a magnification of -0.5, and Table 4 shows the first objective lens and the ultra low magnification of the magnification of -1. It is lens data of an extra low magnification auxiliary lens. In each table, βa is the lateral magnification when the optical system of Table 3 (the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification) is combined with a second objective lens described later, and βb is the optical system of Table 4. Lateral magnification when the first (low-magnification first objective lens and very-low-magnification auxiliary lens) are combined with a second objective lens described later; A. Is the numerical aperture on the object side of the first objective lens for extremely low magnification, and the actual field of view is the diameter of the actual field of view of the first objective lens for extremely low magnification, the entrance pupil distance and the object distance are all on the first surface (most object). The total length is the distance from the sample surface (object surface) to the most image-side lens surface of the extra low magnification auxiliary lens S, and the focal length is the objective lens. The distance along the optical axis between the body surface Z and the sample surface O when mounted on the revolver, f
a is the combined focal length of the first objective lens for extra low magnification and the auxiliary lens for extra low magnification in Table 3, and fb is the combined focal length of the first objective lens for extra low magnification and the auxiliary lens for extra low magnification in Table 4. Is shown. In Tables 3 and 4, the leftmost numeral is the surface number, r is the radius of curvature of each lens surface, d is the lens surface interval,
nd represents the refractive index for the d-line, and νd represents the Abbe number for the d-line. The surface number 9 in Table 3
The surface numbers 8-10 in -11 and Table 4 correspond to the lens data of the extra low magnification auxiliary lens commonly used in the ultra low magnification first objective lenses having different magnifications in Tables 3 and 4. .

[0043]

[Table 3] βa = -0.5x, NA = 0.025, real field of view = 50, entrance pupil = 物体 object distance = 7.8, total length = 184, parfocal length = 60, fa = 392.7 plane rd nd νd 1 55.364 7.5 1.796681 45.37 2 299.253 0.2 1 3 58.487 9 1.787971 47.47 4 -1000.58 3 1.756920 31.62 5 63.39 25.1 1 6 -74.523 2 1.651599 58.5 7 13.54 4.6 1.804581 25.5 8 18.3 118.8 1 9 -280.994 4 1.61720 54.01 10 -32.369 2 1.75692 31.62 11 -56.067

[0044]

[Table 4] βb = −1 ×, NA = 0.05, real field of view φ = 25, entrance pupil = ∞, object distance = 23.2, overall length = 184, parfocal length = 60, fb = 204.3 plane rd nd νd 1 -71.514 17 1.796681 45.37 2 -55.691 0.2 1 3 28.108 16 1.60311 60.65 4 -42.967 2.5 1.671629 38.8 5 -213.923 6.3 1 6 -54.121 2.4 1.651599 58.5 7 21.196 110.4 1 8 -280.994 4 1.617200 54.01 9 -32.369 2 1.756920 31.62 10 -56.067 Example 3] FIGS. 8 and 9 show the very low magnification first embodiment of the third embodiment.
FIG. 9 is a lens configuration diagram showing an objective lens and an auxiliary lens S for extremely low magnification, and a first objective lens for extremely low magnification in FIG.
The first objective lens for extremely low magnification in FIG. 9 has a magnification of -1.

The very low magnification first objective lens shown in FIG. 8 and the very low magnification first objective lens shown in FIG.
Side) in order from the first group 1 having a positive refractive power and the second group having a negative refractive power.
And group 2. On the image side of the first objective lens for ultra-low magnification, an auxiliary lens S for ultra-low magnification having a positive refractive power is arranged. In the very low magnification first objective lens of FIG. 8, the first group 1 includes, in order from the object side, a meniscus positive lens having a convex surface facing the object side, a meniscus positive lens having a convex surface facing the object side, and an object. And a cemented lens composed of a negative meniscus lens with the convex surface facing the side.
The second group 2 is composed of a cemented lens composed of a biconcave lens having a strong concave surface facing the image side and a meniscus positive lens having a convex surface facing the object side.

In the very low magnification first objective lens shown in FIG.
The first unit 1 includes, in order from the object side, a plano-convex lens having a convex surface facing the image side, and a cemented lens composed of a biconvex lens and a biconcave lens having a strong concave surface facing the object side. The second unit 2 includes a biconcave negative lens having a strong concave surface facing the image side. Then, the extra low magnification auxiliary lens S of the third embodiment
Is composed of a cemented lens composed of a positive meniscus lens having a convex surface facing the image side and a negative meniscus lens having a convex surface facing the image side.

Tables 5 and 6 below show lens data of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 3. Here, Table 5 shows the lens data of the ultra-low magnification objective lens and the extra low magnification auxiliary lens with a magnification of -0.5, and Table 6 shows the first objective lens and the ultra low magnification of the magnification of -1. It is lens data of an extra low magnification auxiliary lens. In each table, βa is the lateral magnification when the optical system of Table 5 (the first objective lens for ultra-low magnification and the auxiliary lens for ultra-low magnification) is combined with a second objective lens described later, and βb is the optical system of Table 6. Lateral magnification when the first (low-magnification first objective lens and very-low-magnification auxiliary lens) are combined with a second objective lens described later; A. Is the numerical aperture on the object side of the first objective lens for extremely low magnification, and the actual field of view is the diameter of the actual field of view of the first objective lens for extremely low magnification, the entrance pupil distance and the object distance are all on the first surface (most object). The total length is the distance from the sample surface (object surface) to the most image-side lens surface of the extra low magnification auxiliary lens S, and the focal length is the objective lens. The distance along the optical axis between the body surface Z and the sample surface O when mounted on the revolver, f
a is the composite focal length of the first objective lens for ultra low magnification and the auxiliary lens for ultra low magnification in Table 5, and fb is the composite focal length of the first objective lens for ultra low magnification and the auxiliary lens for ultra low magnification in Table 6. Is shown. In Tables 5 and 6, the leftmost numeral is the surface number, r is the radius of curvature of each lens surface, d is the lens surface interval,
nd represents the refractive index for the d-line, and νd represents the Abbe number for the d-line. The surface number 9 in Table 5
The surface numbers 8-10 in -11 and Table 6 correspond to the lens data of the extra low magnification auxiliary lens commonly used for the ultra low magnification first objective lenses having different magnifications in Tables 5 and 6. .

[0048]

[Table 5] βa = -0.5x, NA = 0.025, real field of view = 50, entrance pupil = 物体 object distance = 7.8, overall length = 181.5, parfocal length = 60, fa = 397.4 surface rd nd νd 1 47.761 8.5 1.787971 47.47 2 478.836 0.2 1 3 40.27 7.5 1.648311 33.75 4 200.049 4 1.748099 52.30 5 41.174 19.2 1 6 -87.496 2 1.748099 52.3 7 14.4 4 1.804581 25.5 8 19.597 122.8 1 9 -244.67 3.5 1.658440 50.84 10 -31.533 2 1.756920 31.62 11 -59.519

[0049]

[Table 6] βb = −1 ×, NA = 0.05, real field of view φ = 25, entrance pupil = ∞, object distance = 17.2, overall length = 181.5, parfocal length = 60, fb = 202.7 plane rd nd νd 1 ∞ 20 1.748099 52.3 2 -142.75 0.5 1 3 39.434 10 1.787971 47.47 4 -31.5 9 1.625882 35.7 5 119.327 2.9 1 6 -48.611 2.4 1.516800 64.1 7 21 114 1 8 -244.67 3.5 1.658440 50.84 9 -31.533 2 1.756920 31.62 10 -59.519 Example 4 10 and 11 are lens configuration diagrams showing an extremely low magnification first objective lens and an extremely low magnification auxiliary lens S of Embodiment 4, and the first extremely low magnification first objective lens in FIG. The first objective lens for extremely low magnification shown in FIG. 11 has a magnification of -1.

An extremely low magnification first objective lens shown in FIG.
The very low magnification first objective lens shown in FIG. 11 includes, in order from the object side (sample O side), a first group 1 having a positive refractive power and a second group 2 having a negative refractive power. In addition, these very low magnification first
On the image side of the objective lens, an extremely low magnification auxiliary lens S having a positive refractive power is arranged. In the very low magnification first objective lens shown in FIG. 10, the first group 1 includes, in order from the object side, a meniscus positive lens having a convex surface facing the object side, and a cemented lens including a biconvex lens and a biconcave lens. Is done. The second group 2 is composed of a cemented lens composed of a biconcave lens having a strong concave surface facing the image side and a meniscus positive lens having a convex surface facing the object side.

In the very low magnification first objective lens shown in FIG. 11, the first lens unit 1 comprises, in order from the object side, a cemented lens composed of a biconvex lens and a negative meniscus lens having a concave surface facing the object side. The second group 2 includes a biconcave lens having a strong concave surface facing the image side and a meniscus positive lens having a convex surface facing the object side. The extra low magnification auxiliary lens S of Example 4 is composed of a cemented lens including a positive meniscus lens having a convex surface facing the image side and a negative meniscus lens having a convex surface facing the image side.

Tables 7 and 8 below show lens data of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 4. Here, Table 7 shows the lens data of the ultra-low magnification objective lens and the extra low magnification auxiliary lens with a magnification of -0.5, and Table 8 shows the first objective lens and the ultra low magnification of the magnification of -1. It is lens data of an extra low magnification auxiliary lens. In each table, βa is the lateral magnification when the optical system of Table 7 (the first objective lens for ultra-low magnification and the auxiliary lens for ultra-low magnification) is combined with a second objective lens described later, and βb is the optical system of Table 8. Lateral magnification when the first (low-magnification first objective lens and very-low-magnification auxiliary lens) are combined with a second objective lens described later; A. Is the numerical aperture on the object side of the first objective lens for extremely low magnification, and the actual field of view is the diameter of the actual field of view of the first objective lens for extremely low magnification, the entrance pupil distance and the object distance are all on the first surface (most object). The total length is the distance from the sample surface (object surface) to the most image-side lens surface of the extra low magnification auxiliary lens S, and the focal length is the objective lens. The distance along the optical axis between the body surface Z and the sample surface O when mounted on the revolver, f
a is the combined focal length of the first objective lens for ultra low magnification and the auxiliary lens for ultra low magnification in Table 7, and fb is the composite focal length of the first objective lens for ultra low magnification and the auxiliary lens for ultra low magnification in Table 8. Is shown. In Tables 7 and 8, the leftmost numeral is the surface number, r is the radius of curvature of each lens surface, d is the lens surface interval,
nd represents the refractive index for the d-line, and νd represents the Abbe number for the d-line. The surface number 9 in Table 7
-11 and Table 8 in Table 8 correspond to Tables 7 and 8, respectively.
Corresponds to the lens data of the extra low magnification auxiliary lens commonly used for the ultra low magnification first objective lenses having different magnifications.

[0053]

[Table 7] βa = −0.5 ×, NA = 0.025, real field of view φ = 50, entrance pupil = ∞, object distance = 7.8, total length = 176, parfocal length = 60, fa = 400 planes rd nd νd 1 35.286 10 1.787971 47.47 2 152.875 0.2 1 3 70.552 10.5 1.620409 60.14 4 -83.348 3 1.755200 27.61 5 109.113 14.8 1 6 -32.066 2 1.620409 60.14 7 12.504 4.6 1.804581 25.5 8 15.986 117.1 1 9 -212.087 4 1.622801 57.03 10 -29.568 2 1.749501 35.19 11 -52.013

[0054]

[Table 8] βb = −1 ×, NA = 0.04, real field of view φ = 25, entrance pupil = ∞, object distance = 34.1, total length = 176, parfocal length = 60, fb = 200.1 plane rd nd νd 1 43.063 10 1.620409 60.14 2 -23.25 2 1.749501 35.19 3 -67.373 16.5 1 4 -824.161 2 1.526820 51.35 5 12.198 4 1.784721 25.8 6 15.881 101.4 1 7 -212.087 4 1.622801 57.03 8 -29.568 2 1.749501 35.19 9 -52.013 In the above examples, There is a case in which the second lens group protrudes to the image side of the barrel mounting surface Z. The lens barrel holding the first and second lens groups is, as shown in FIG. An external thread is formed on the image side of Z, and the second lens group protruding on the image side of the barrel-attached surface Z can be accommodated in this portion of the lens barrel, so that there is no problem.

Table 9 below shows conditions corresponding values of each embodiment.

[0056]

Table 9 Example 1 Example 2 Example 3 Example 4 (1) (D + L) / fS 1.3 1.31 1.28 1.3 (2) L 124 124 121.5 116 (3) | ν1S−ν2S | 21.84 22.39 19.22 21.84 (4) | βa | 0.5 0.5 0.5 0.5 (5) f1a / fa 0.15 0.17 0.15 0.13 (6) | βb | / | βa | 2.0 2.0 2.0 2.0 (7) f1b / fb 0.19 0.17 0.19 0.26 (8) (t1b + t2b) / D 0.63 0.63 0.69 0.3 (9) | βb | 1.0 1.0 1.0 1.0 FIGS. 12 to 19 show various aberration diagrams of the above embodiments. Each of these aberration diagrams is an aberration diagram when the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of the embodiment are combined with a second objective lens having a focal length of 200 mm. FIG. 20 shows the lens configuration of the second objective lens used for obtaining these aberration diagrams, and the lens data is shown in Table 10 below. In Table 10, the leftmost numeral is the surface number, r is the radius of curvature of each lens surface, d is the distance between the lens surfaces, nd is the refractive index for d-line, and νd is the Abbe number for d-line.

[0057]

[Table 10] Surface r d nd νd 1 75.043 5.1 1.622801 57.033 2 -75.043 2 1.749501 35.19 3 1600.58 7.5 1 4 50.256 5.1 1.667551 41.96 5 -84.541 1.8 1.612658 44.41 6 36.911

12 to 19, (a) is a spherical aberration diagram, (b) is an astigmatism diagram, and (c)
Is distortion, (d) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram. In each aberration diagram, NA is the image-side numerical aperture, Y is the image height, D is the d-line (587.6 nm), F is the F-line (486.1).
nm), C represents the C line (656.3 nm), and G represents the g line (435.8 nm). Also, in the aberration diagram showing spherical aberration, the sine condition violation amount is shown by a broken line, in the aberration diagram showing astigmatism, the sagittal image plane is shown by a solid line, and the meridional image plane is shown by a broken line. In the aberration diagram showing the lateral aberration, the image height 1
The figure shows 0%, 70% image height, and on-axis lateral aberration.

As is clear from the various aberration diagrams, the various aberrations are satisfactorily corrected in each embodiment even though the common extra low magnification auxiliary lens is used. The extra low magnification auxiliary lens in each of the above embodiments is a group of cemented lenses having a positive refractive power as a whole.
The present invention is not limited to this configuration, and may be a combination of a positive lens and a negative lens separated by an air space, or may be composed of three or more lens elements.

[0060]

As described above, in the microscope according to the present invention,
Observation or photographing of a sample can be made possible at a plurality of magnification states in an extremely low magnification range. Further, the first objective lens for ultra low magnification according to the present invention has an advantage that one kind of auxiliary lens can cope with the first objective lens for ultra low magnification of a plurality of magnifications, and the aberration is well corrected. There is also an advantage that a wide-field image can be observed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a microscope according to an embodiment of the present invention. FIG. 1A illustrates a case where observation is performed at an extremely low magnification.
(B) shows a case where observation is performed in a normal magnification state.

FIG. 2 is an enlarged view showing a main part of the microscope shown in FIG.

FIG. 3 is a diagram schematically showing a modification of the embodiment according to the present invention.

FIG. 4 is an optical path diagram of an extremely low magnification first objective lens and an extremely low magnification auxiliary lens in Example 1.

5 is an optical path diagram of an extremely low magnification first objective lens and an extremely low magnification auxiliary lens having a magnification different from that of the extremely low magnification first objective lens in FIG. 4 in Example 1. FIG.

FIG. 6 is an optical path diagram of a first objective lens for extremely low magnification and an auxiliary lens for extremely low magnification in Example 2.

7 is an optical path diagram of an extremely low magnification first objective lens and an extremely low magnification auxiliary lens having a magnification different from that of the extremely low magnification first objective lens of FIG. 6 in Example 2. FIG.

FIG. 8 is an optical path diagram of an extremely low magnification first objective lens and an extremely low magnification auxiliary lens in Embodiment 3.

9 is an optical path diagram of an extremely low magnification first objective lens and an extremely low magnification auxiliary lens having a magnification different from that of the extremely low magnification first objective lens of FIG. 8 in Embodiment 3. FIG.

FIG. 10 is an optical path diagram of a first objective lens for extremely low magnification and an auxiliary lens for extremely low magnification in Example 4.

11 is an optical path diagram of an extremely low magnification first objective lens and an extremely low magnification auxiliary lens having a magnification different from that of the extremely low magnification first objective lens of FIG. 10 in Example 4. FIG.

12A and 12B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification in Example 1, where FIG. 12A is a spherical aberration diagram, FIG. 12B is an astigmatism diagram, and FIG. Is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

13A and 13B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 1 illustrated in FIG. 5, where FIG. 13A is a spherical aberration diagram and FIG. 13B is an astigmatism diagram. , (C) is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

14A and 14B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification in Example 2, where (a) is a spherical aberration diagram, (b) is an astigmatism diagram, and (c). Is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

15A and 15B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 2 illustrated in FIG. 7, where FIG. 15A is a spherical aberration diagram and FIG. 15B is an astigmatism diagram. , (C) is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

16A and 16B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification in Example 3, where FIG. 16A is a spherical aberration diagram, FIG. 16B is an astigmatism diagram, and FIG. Is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

17A and 17B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 3 illustrated in FIG. 9, where FIG. 17A is a spherical aberration diagram and FIG. , (C) is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

18A and 18B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification in Example 4, in which (a) is a spherical aberration diagram, (b) is an astigmatism diagram, and (c). Is distortion,
(D) is a lateral aberration diagram, and (e) is a chromatic aberration of magnification diagram.

19A and 19B are diagrams illustrating various aberrations of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification of Example 1 illustrated in FIG.
Is a spherical aberration diagram, (b) is an astigmatism diagram, (c) is a distortion aberration, (d) is a lateral aberration diagram, and (e) is a magnification chromatic aberration diagram.

FIG. 20 is a lens configuration diagram of a second objective lens.

[Explanation of symbols]

 O: Object surface Z: Body surface D: Parfocal length 1: First lens group 2: Second lens group S: Extra low magnification auxiliary lens

Claims (9)

(57) [Claims] A revolver configured to be mountable with the plurality of first objective lenses so that the plurality of first objective lenses can be switched with respect to an optical path; A microscope provided with a second objective lens provided at a position where a light beam from the first objective lens located in the optical path is guided and condensing the light beam to form a real image of an object, wherein the first objective lens and the An ultra-low magnification auxiliary lens having a positive refracting power and provided in the optical path between the second objective lens and the revolver, the revolver being disposed on the image side of the first positive lens group and the positive lens group; A first low-magnification first objective lens comprising a second negative lens group disposed therein is configured to be mountable; and when the first ultra-low magnification first objective lens is positioned in the optical path, the very-low magnification auxiliary lens is disposed. Is located in the optical path and satisfies the following conditions: A featured microscope. 1 ≦ (D + L) /fS≦1.5 50 ≦ L ≦ 200 12 ≦ | ν1S−ν2S | where D: parfocal length of the microscope, fS: focal length of the extra low magnification auxiliary lens, ν1S: Abbe number of the lens element having the largest Abbe number among the lens elements constituting the extra low magnification auxiliary lens, and ν2S: the lens element having the smallest Abbe number among the lens elements constituting the extra low magnification auxiliary lens. Abbe's number, L: distance from the body-mounted surface of the objective lens to the most image-side lens surface of the extra low magnification auxiliary lens. 2. A detecting means for outputting a predetermined signal when the extremely low magnification first objective lens is positioned in the optical path, and selectively moving the extremely low magnification auxiliary lens into and out of the optical path. A driving unit, and a control unit that controls the driving unit to move the extra low magnification auxiliary lens into the optical path based on the predetermined signal from the detection unit. Item 7. The microscope according to Item 1. 3. The focal length of the first group of the first objective lens for extremely low magnification is f1a, and the combined focal length of the first objective lens for extremely low magnification and the auxiliary lens for extremely low magnification is fa. The following condition is satisfied when a combined lateral magnification of the first objective lens for extremely low magnification, the auxiliary lens for extremely low magnification, and the second objective lens is βa.
Or the microscope according to 2. | Βa | ≦ 1.5 0.07 ≦ f1a / fa ≦ 0.25 4. The ultra-low magnification first objective lens, wherein the plurality of first objective lenses include another ultra-low magnification first objective lens having a magnification different from that of the ultra-low magnification first objective lens. The objective lens includes a positive first group and a negative second group disposed on the image side of the positive lens group. When the another ultra-low magnification first objective lens is located in the optical path, The microscope according to any one of claims 1 to 3, wherein an extremely low magnification auxiliary lens is located in the optical path. 5. A composite lateral magnification of the first objective lens for extremely low magnification, the auxiliary lens for extremely low magnification and the second objective lens is β.
a, and the combined lateral magnification of the another extra-low magnification first objective lens, the extra-low magnification auxiliary lens, and the second objective lens is β
When b, 1.25 ≦ | βb | / | βa | ≦ 2.75 is satisfied, and the following condition is further satisfied:
Microscope as described. 0.1 ≦ f1b / fb ≦ 0.5 0.2 ≦ (t1b + t2b) /D≦0.8, where f1b: the focal length of the first group of the another ultra-low magnification first objective lens, fb: the above The combined focal length of another extra low magnification first objective lens and the extra low magnification auxiliary lens, t1b: the total value of the lens center thickness of the first group of the other extra low magnification first objective lens, t2b : Total value of the lens center thickness of the second group of the another ultra-low magnification first objective lens, D: Parfocal length of the microscope. 6. A revolver to which a plurality of first objective lenses can be mounted, a second objective lens for collecting a light beam from the first objective lens to form a real image, the first objective lens and the second objective lens. It is configured to be attachable to a microscope having an extra-low magnification auxiliary lens that is detachably provided in an optical path between the objective lens and a first lens unit having a positive refractive power and a negative lens having a negative refractive power in order from the object side. Second
A microscope comprising a first objective lens for ultra-low magnification, comprising a group and satisfying the following conditions. | Βa | ≦ 1.5 0.07 ≦ f1a / fa ≦ 0.25 where f1a is the focal length of the first group, and fa is the focal length of the first group, the second group, and the extra low magnification auxiliary lens. Synthetic focal length, βa: synthetic lateral magnification of the first objective lens for extremely low magnification, the auxiliary lens for extremely low magnification, and the second objective lens. 7. A revolver to which a plurality of first objective lenses can be mounted, a second objective lens for condensing a light beam from the first objective lens to form a real image, the first objective lens and the second objective lens. It is configured to be attachable to a microscope having an extra-low magnification auxiliary lens that is detachably provided in an optical path between the objective lens and a first lens unit having a positive refractive power and a negative lens having a negative refractive power in order from the object side. Second
A microscope comprising a first objective lens for ultra-low magnification, comprising a group and satisfying the following conditions. | Βb | ≦ 1.5 0.1 ≦ f1b / fb ≦ 0.5 0.2 ≦ (t1b + t2b) /D≦0.8 where f1b is the focal length of the first group, fb is the first group, Composite focal length of the second group and the extra low magnification auxiliary lens; t1b: total value of the lens center thickness of the first group; t2b: total value of the lens center thickness of the second group; Focal length, βb: composite lateral magnification of the extremely low magnification first objective lens, the extremely low magnification auxiliary lens, and the second objective lens. 8. The ultra-low magnification auxiliary lens has a positive refractive power and satisfies the following condition.
Microscope as described. 1 ≦ (D + L) /fS≦1.5 50 ≦ L ≦ 200 12 ≦ | ν1S−ν2S | where D: parfocal length of the microscope, fS: focal length of the extra low magnification auxiliary lens, ν1S: Abbe number of the lens element having the largest Abbe number among the lens elements constituting the extra low magnification auxiliary lens, and ν2S: the lens element having the smallest Abbe number among the lens elements constituting the extra low magnification auxiliary lens. Abbe's number, L: distance from the body-mounted surface of the objective lens to the most image-side lens surface of the extra low magnification auxiliary lens. 9. A revolver having a positive refracting power and capable of mounting a very low magnification first objective lens composed of a positive first unit and a negative second unit in order from the object side, and the revolver In the optical path between the first objective lens for extremely low magnification and the second objective lens in a microscope having a second objective lens that forms a real image of an object by condensing light from a lens system mounted on the optical system. Wherein the first objective lens for ultra low magnification is located in the optical path when the first objective lens for ultra low magnification is located in the optical path, and the following conditions are satisfied: A microscope with a magnification auxiliary lens. 1 ≦ (D + L) /fS≦1.5 50 ≦ L ≦ 200 12 ≦ | ν1S−ν2S | where D: parfocal length of the microscope, fS: focal length of the extra low magnification auxiliary lens, ν1S: Abbe number of the lens element having the largest Abbe number among the lens elements constituting the extra low magnification auxiliary lens, and ν2S: the lens element having the smallest Abbe number among the lens elements constituting the extra low magnification auxiliary lens. Abbe's number, L: distance from the body-mounted surface of the objective lens to the most image-side lens surface of the extra low magnification auxiliary lens.