JP7214192B2 - Immersion microscope objective lens, imaging lens and microscope device - Google Patents

Description

The present invention relates to a microscope objective lens system. In particular, the present invention relates to an immersion microscope objective lens of about 10 to 20 magnifications, and a microscope apparatus using this infinite immersion microscope objective lens. It also particularly relates to an imaging lens and a microscope apparatus using this imaging lens.

Generally, a microscope objective lens system consists of a microscope objective lens and an imaging lens.
Among microscope objective lens systems, microscope objective lenses, particularly liquid immersion microscope objective lenses, are known, for example, as described in Patent Documents 1 and 2 below.
Further, among microscope objective lens systems, as imaging lenses, for example, those described in Patent Documents 3 and 4 below are known.

JP 2005-189732 JP 2017-161651 Japanese Patent Laid-Open No. 57-195212 JP 2016-75860

With conventional immersion microscope objective lenses and microscope objective lens systems such as imaging lenses, a sharp image can be obtained in the center and vicinity of the screen, but the image is unclear from the middle to the periphery of the screen. was

SUMMARY OF THE INVENTION It is an object of the present invention to provide a microscope objective lens system that provides a sharp image on the entire screen from the center to the periphery.

To achieve the above object, an immersion microscope objective lens according to a first aspect of the present invention has a positive refractive power as a whole and is composed of two or more lenses in order from the object OBJ side. A first lens group G1, a second lens group G2 having positive refractive power as a whole, including a three-lens cemented lens and composed of seven or more lenses, and two or more lenses. including a third lens group G3, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 composed of two or more lenses for emitting a parallel light beam, and at least the third lens Either the lens group G3 or the fifth lens group G5 has a lens configuration of three or more lenses, and at least the third lens group G3 is provided with a bonding surface C2 having a convex surface facing the object side. Alternatively, when the fifth lens group G5 is provided with a cemented surface C1 having a concave surface facing the object side, the maximum image height is Ih, and the maximum effective radius of the lens is RDmax, the following condition (1 ).
0.35<Ih/RDmax<2.2 (1)

In order to achieve the above object, the imaging lens according to the second aspect of the present invention includes at least one lens with positive refractive power and one lens with negative refractive power in order from the object OBJ side. including a first lens group IG1, a second lens group IG2 including at least one positive refractive power lens, at least one positive refractive power lens and one negative refractive power lens, and negative refractive power as a whole Lp is the distance from the lens surface closest to the object side of the first lens group IG1 to the pupil plane, and fIm is the focal length of the entire system. It satisfies condition (2).
-5.0<Lp/fIm<-0.5 (2)

To achieve the above object, a microscope apparatus according to a third aspect of the present invention comprises an illumination optical system for illuminating an object, and an immersion system according to the first aspect for forming an image of the object. It includes a microscope objective lens and an imaging lens, and an observation system for observing the image.

Furthermore, in order to achieve the above object, a microscope apparatus according to a fourth aspect of the present invention comprises an illumination optical system for illuminating an object, an immersion microscope objective lens for forming an image of the object, and An imaging lens according to the second aspect, and an observation system for observing the image.

According to the present invention, an immersion microscope objective lens and an imaging lens that have a high numerical aperture, have excellent flatness in all wavelength bands used, and provide sharp images even in the middle part and the peripheral part of the screen, and It is possible to provide a microscope apparatus comprising said immersion microscope objective or said imaging lens.

1 shows an immersion microscope objective lens of a first embodiment according to the present invention; FIG. FIG. 4 is a diagram of various aberrations of the first embodiment; FIG. 4 shows an immersion microscope objective lens of a second embodiment according to the present invention; FIG. 10 is a diagram of various aberrations of the second embodiment; FIG. 11 shows an immersion microscope objective lens of a third embodiment according to the present invention; FIG. 10 is a diagram of various aberrations of the third embodiment; FIG. 4 shows an imaging lens of a fourth embodiment according to the present invention; FIG. 10 is a diagram of various aberrations of the fourth embodiment; FIG. 10 is a diagram showing an imaging lens of a fifth embodiment according to the present invention; FIG. 10 is a diagram of various aberrations of the fifth embodiment; FIG. 10 is a diagram showing an imaging lens of a sixth embodiment according to the present invention; FIG. 10 is a diagram of various aberrations of the sixth embodiment;

An immersion microscope objective lens, an imaging lens, and a microscope apparatus having the immersion microscope objective lens or imaging lens according to embodiments and examples of the present invention will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals.

First, the immersion microscope objective lens of the first embodiment will be described.
The immersion microscope objective lens according to the first embodiment is basically the immersion microscope objective lens according to the first aspect described above. The number of lenses in the second lens group G2 is seven or more, a fourth lens group G4 with negative refractive power is provided, and at least one of the third lens group G3 or the fifth lens group G5 is composed of three or more lenses. At least in the third lens group G3, a bonding surface C2 with a convex surface facing the object side is provided, or in the fifth lens group G5, a bonding surface C1 with a concave surface facing the object side is provided. , the field curvature and chromatic aberration of the immersion microscope objective lens are well corrected.

The immersion microscope objective lens is a microscope objective lens that fills a space between the object OBJ and the first lens group G1 with liquid.

Condition (1) is a condition that particularly defines a preferable size of the objective lens. If the lower limit of condition (1) is not reached, the lens diameter becomes too large, making it difficult to adapt to an actual device. If the upper limit of condition (1) is exceeded, the lens diameter becomes too small, making it difficult to correct aberrations, which is not preferable. A lower limit of 0.45 gives even better results, and a lower limit of 0.47 gives very good results.

The maximum image height is a value obtained by multiplying the maximum object height of the object OBJ by the magnification of the objective lens of the microscope, and the maximum effective radius of the lens is the radius of the lens where the light beam involved in imaging spreads most.

Moreover, particularly in this embodiment, the fifth lens group G5 is adapted to emit a parallel light beam. This enables attachment to various microscopes, increasing the versatility of the immersion microscope objective lens.
Further, it is preferable that the fourth lens group G4 is arranged in contact with the third lens group G3, and the fifth lens group G5 is arranged in contact with the fourth lens group G4.

In the immersion microscope objective lens according to the second embodiment, when the bonding surface facing the object OBJ provided in the fifth lens group G5 and facing the concave surface is the first bonding surface C1, , the refractive power of the first bonding surface C1 is positive, the refractive indices of the media on both sides of the first bonding surface C1 are n6 and n7, respectively, and the radius of curvature of the first bonding surface C1 is is R1, and the focal length of the entire microscope objective lens system is f, it is preferable to satisfy the following condition (3).
0.07 <｜(n6-n7)×f/R1 ｜< 1.2 (3)

This condition is for satisfactorily correcting chromatic coma in the meridional direction. In this specification, chromatic coma means a difference in coma at each wavelength in the visible light range. Exceeding the upper limit of the condition (3) is not preferable because the shape of the lens becomes disadvantageous in manufacturing. If the lower limit of condition (3) is not reached, correction of chromatic coma in the meridional direction becomes difficult, which is not preferable.

In order to further improve the performance of the immersion microscope objective lens according to the third embodiment, it is preferable that the first lens group G1 is composed of four or more lenses. In particular, the first lens group G1 includes a negative lens, a biconvex lens, a meniscus lens with a concave surface facing the first object OBJ side, and a meniscus lens with a concave surface facing the second object OBJ side, is preferably included.

Further, in the immersion microscope objective lens according to the fourth embodiment, the meniscus lens with the concave surface facing the first object OBJ side is a meniscus lens with the concave surface facing the first object OBJ side. When the refractive index is n3, it is preferable to satisfy the following condition (4).
n3 > 1.7 (4)

This condition (4) is a condition for satisfactorily correcting the spherical aberration and the Petzval sum. If the condition (4) is not met, spherical aberration and Petzval sum cannot be satisfactorily corrected. A lower limit of 1.75 gives even better results. This meniscus lens may be either a cemented lens or a single lens.

In the immersion microscope objective lens according to the fifth embodiment, the first lens group G1 has a bonding surface with a convex surface facing the object OBJ side, and a bonding surface with a convex surface facing the object side. When the refractive index of the medium on the object OBJ side of the mating surface is n1 and the refractive index of the medium on the opposite side is n2, it is preferable to satisfy the following condition (5).
n1-n2>0.10 (5)

This condition (5) is a condition for satisfactorily correcting high-order chromatic spherical aberration. If the lower limit of condition (5) is not reached, it becomes difficult to satisfactorily correct high-order chromatic spherical aberration. Even better results are obtained with a lower limit of 0.15.

Further, in the immersion microscope objective lens according to the sixth embodiment, the second bonding surface C2 is the bonding surface facing the object OBJ provided in the third lens group G3. Then, the refractive power of the second bonding surface C2 is positive, the refractive indices of the media on both sides of the second bonding surface C2 are n4 and n5, respectively, and the refractive power of the second bonding surface C2 is When the radius of curvature is R2 and the focal length of the entire microscope objective lens system is f, it is preferable to satisfy the following condition (6).
0.07 <｜(n4-n5)×f/R2｜< 1.2 (6)

This condition (6) is a condition for satisfactorily correcting chromatic coma in the meridional direction. Exceeding the upper limit of the condition (6) is not preferable because the shape of the lens becomes disadvantageous in manufacturing. If the lower limit of condition (6) is not reached, correction of chromatic coma in the meridional direction becomes difficult, which is not preferable.

Further, in the immersion microscope objective lens according to the seventh embodiment, it is preferable that the lens surface of the first lens group closest to the object OBJ is flat. On the concave surface, there is a possibility that air bubbles may be mixed in during actual use.

In the immersion microscope objective lens according to the eighth embodiment, the second lens group G2 preferably includes at least two cemented three-lens lenses. By doing so, the secondary dispersion can be reduced.

In the immersion microscope objective lens according to the ninth embodiment, the radius of curvature of the concave surface C3 having negative refractive power that appears first when counted from the object OBJ is set to R3, and the negative refractive power that appears first from the object OBJ is set to R3. When the distance to the concave surface C3 having a refractive power of d is d, it is preferable to satisfy the following condition (7).
-0.3>d/R3>-1.5 (7)

This condition (7) is a condition for satisfactorily correcting spherical aberration in particular. Exceeding the upper limit of condition (7) is not preferable because the total length of the lens becomes long. Further, if the lower limit of the condition (7) is not reached, a large amount of spherical aberration occurs, which is not preferable.

In the immersion microscope objective lens according to the tenth embodiment, the distance from the object OBJ surface to the final lens surface of the microscope objective lens is LL, and the principal ray corresponding to the maximum image height emitted from the microscope objective lens is is the angle .theta., it is preferable to satisfy the following condition (8).
0.00063<tan θ/LL<0.00105 (8)

This condition (8) is a condition for making the overall size of the lens suitable while maintaining good performance. Exceeding the upper limit of condition (8) is not preferable because the overall length of the lens becomes short, making it difficult to obtain good performance. Further, if the lower limit of the condition (8) is not reached, the total length of the lens becomes too long, and the lens cannot be attached to the microscope apparatus, which is not preferable.

In the immersion microscope objective lens according to the eleventh embodiment, the third lens group G3 preferably includes a cemented meniscus lens having a convex surface facing the object OBJ side. In particular, when the bonded meniscus lens is a three-lens bonded meniscus lens, it is possible to perform even better aberration correction.

Further, in the immersion microscope objective lens according to the twelfth embodiment, when the radius of curvature of the concave surface C4 of the cemented meniscus lens of the third lens group G3 facing the object side is R4, the following It is preferable to satisfy condition (9).
0.35<|R4|/f<2 (9)

This condition (9) is a condition for maintaining good planarity. This is also a condition for giving a large refractive power to the concave surface C4. Exceeding the upper limit of condition (9) is not preferable because the overall length of the lens becomes short, making it difficult to obtain good performance. If the lower limit of the condition (9) is not reached, the total length of the lens becomes too long, and the lens cannot be attached to the microscope apparatus, which is not preferable.

In the immersion microscope objective lens according to the thirteenth embodiment, the fifth lens group G5 preferably includes a cemented meniscus lens having a concave surface facing the object OBJ side. In particular, when the bonded meniscus lens is a three-lens bonded meniscus lens, it is possible to perform even better aberration correction.

Furthermore, in the immersion microscope objective lens according to the fourteenth embodiment, when the radius of curvature of the concave surface C5 of the cemented meniscus lens of the fifth lens group G5 facing the object OBJ side is R5, the following It is preferable to satisfy the condition (10) of
0.4<|R5|/f<2.5 (10)

This condition (10) is a condition for maintaining good flatness of the image plane. This is a condition for giving a large refractive power to the concave surface C5. Exceeding the upper limit of condition (10) is not preferable because the total length of the lens becomes short, making it difficult to obtain good performance. Further, if the lower limit of the condition (10) is not reached, the total length of the lens becomes too long, making it difficult to attach the lens to the microscope apparatus, which is not preferable.

Further, the immersion microscope objective lens according to the fifteenth embodiment preferably satisfies the following condition (11), where f4 is the focal length of the fourth lens group G4.
0.5<|f4|/f<2 (11)

This condition (11) is a condition that defines an appropriate refractive power of the fourth lens group. If the upper limit of the condition (11) is exceeded, the total length of the lens becomes short, making it difficult to obtain good performance, which is not preferable. If the lower limit of condition (11) is not reached, the total length of the lens becomes too long, making it difficult to attach the lens to a microscope apparatus, which is not preferable.

Further, in the immersion microscope objective lens according to the sixteenth embodiment, the distance between the third lens group G3 and the fourth lens group G4 is set to d3, and the fourth lens group G4 and the fifth lens group G5 are separated from each other. , the thickness of the cemented meniscus lens of the third lens group G3 facing the object OBJ side is d4, the thickness of the cemented meniscus lens facing the object OBJ side is t3, and the fifth lens group G5 is bonded with the concave surface facing the object OBJ side. When the thickness of the combined meniscus lens is t5, it is preferable to satisfy the following conditions (12) and (13).
d3/t3 <0.75 (12)
d4/t5<0.35 (13)

Conditions (12) and (13) are conditions that define the appropriate shapes of the third lens group and the fifth lens group. Exceeding the upper limits of both conditions (12) and (13) is not preferable because correction of coma aberration becomes difficult.

The imaging lens of the seventeenth embodiment will be described below.
The imaging lens of the seventeenth embodiment is basically an imaging lens according to the second aspect, and in particular, three lens groups are provided, the first lens group IG1 mainly corrects chromatic aberration, and the second lens group IG1 mainly corrects chromatic aberration. By correcting spherical aberration, coma, astigmatism, distortion, and the like in the lens group IG2, field curvature and chromatic aberration of the imaging lens can be satisfactorily corrected.

Condition (2) is a condition that defines an appropriate positional state for the imaging lens. Exceeding the upper limit of condition (2) is not preferable because the size of the entire microscope apparatus becomes too long. On the other hand, if the lower limit of condition (2) is not reached, the distance between the imaging lens and the objective lens becomes too close, which limits the applications of usable objects and lacks versatility of the imaging lens, which is not preferable.

In the imaging lens according to the eighteenth embodiment, the first lens group IG1 is a two-lens cemented lens, and the at least one lens of positive refractive power in the first lens group IG1 has a refractive index nd is 1.61 or less, and the Abbe number ν is 65 or more. By configuring in this way, it is possible to particularly favorably correct chromatic aberration.

Further, the imaging lens according to the nineteenth embodiment has the following conditions (14) and ( 15) is preferably satisfied.
0.03<|fIm/f21|<0.85 (14)
0.70<|fIm/f22|<2.00 (15)

These conditions (14) and (15) are conditions for defining an appropriate refractive power arrangement. If the lower limit of condition (14) is exceeded, the refracting power of the first lens group IG1 becomes too large, and the performance becomes the same as that of a conventional imaging lens, which is not preferable. If the upper limit of the condition (14) is exceeded, the refractive power of the first lens group IG1 becomes too small and cannot contribute to aberration correction, which is not preferable.

If the lower limit of condition (15) is exceeded, the refractive power of the second lens group IG2 becomes too large, the refractive power of the first lens group IG1 becomes small, and various aberrations become worse, which is not preferable. If the upper limit of the condition (15) is exceeded, the refractive power of the second lens group IG2 becomes too small and the refractive power of the first lens group IG1 becomes large, resulting in the same aberration correction state as a conventional imaging lens. so I don't like it.

Further, the imaging lens according to the twentieth embodiment preferably satisfies the following condition (16) when the focal length of the third lens group IG3 is f23.
-2.0<f23/fIm<-0.5 (16)

This condition (16) is a condition for prescribing an appropriate refractive power arrangement. Exceeding the upper limit and the lower limit of condition (16) is not preferable because it is impossible to satisfactorily correct each aberration.

A microscope apparatus according to a twenty-first embodiment comprises an illumination optical system for illuminating an object, and an immersion microscope objective according to any one of the first to sixteenth embodiments for forming an image of the object. It includes a lens, an imaging lens, and an observation system for observing the image.

A microscope apparatus according to a twenty-second embodiment comprises an illumination optical system for illuminating an object, an immersion microscope objective lens for forming an image of the object, and any one of the seventeenth to twentieth embodiments. and an observation system for observing the image.

First, the first, second and third embodiments will be described with reference to FIGS. 1 to 6. FIG. These examples are examples of immersion microscope objectives.

Each embodiment consists of a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, and a fifth lens group G5 in order from the object OBJ side. In the first, second and third embodiments, the space between the object OBJ and the first lens group G1 is filled with water (nd=1.34, νd=57.9) and the distance is 3 mm.

(First embodiment)
The immersion microscope objective lens of the first embodiment will be described with reference to FIGS. 1 and 2(A) to (C). FIG. 1 is a diagram showing an immersion microscope objective lens of a first embodiment according to the present invention.

The first lens group G1 consists of, in order, a cemented lens of a plano-concave lens L11 and a biconvex lens L12, a positive meniscus lens L13 with a concave surface facing the object side, and a positive meniscus lens L14 with a concave surface facing the object side. Configured.

The second lens group G2 includes, in order, a cemented lens of a biconcave lens L21 and a biconvex lens L22, a cemented lens of a biconvex lens L23, a biconcave lens L24, and a biconvex lens L25, and a convex surface facing the object side. It is composed of a three-piece cemented lens consisting of a negative meniscus lens L26, a biconvex lens L27, and a biconcave lens L28.

The third lens group G3 is composed of a triplet cemented lens consisting of a biconvex lens L31, a biconcave lens L32, and a positive meniscus lens L33 having a convex surface facing the object side.
The fourth lens group G4 is composed of a negative meniscus lens L41 having a concave surface facing the object side.

The fifth lens group G5 is composed of a triple cemented lens consisting of a positive meniscus lens L51 with a concave surface facing the object side, a biconcave lens L52, and a biconvex lens L53.

The immersion microscope objective lens of this embodiment has a focal length of 12.4 mm, a magnification of 16 times, an object-side NA of 0.8, a maximum object height of 0.75 mm, and a maximum image height Ih of 12.00 mm.

Table 1 below shows the data for this example. In the table, the surface number, radius of curvature (r), surface spacing (d), refractive index at a wavelength of 588 nm (nd), Abbe number (νd) are shown in order from the left side, and the radius of curvature r, surface spacing d, and For other units of length, "mm" is generally used. However, since the optical system can obtain the same optical performance even if it is proportionally enlarged or proportionally reduced, the unit is not limited to "mm". This display method is the same for Tables 2 to 6, which will be described later.

Values corresponding to the conditions of this embodiment are shown below.
RDmax = 12.13
Ih/RDmax = 0.99
│(n6-n7)×f/R1 │=0.37
|(n4-n5)×f/R2 |=0.38
n1-n2=0.42
d/R3 = -0.63
(tan θ)/LL = 0.000744
|R4|/f=0.69
|R5|/f=1.51
|f4|/f=1.18
d3/t3 = 0.47
d4/t5 = 0.13

2A to 2C are various aberration diagrams of the immersion microscope objective lens of this embodiment, FIG. 2A is a spherical aberration diagram, and FIG. 2B is an astigmatism diagram. , and FIG. 2C shows a distortion diagram. An imaging lens is required to create these aberration diagrams. In the first to third embodiments, an ideal imaging lens with a focal length of 200 mm and no aberrations is used as the imaging lens. there is

In the spherical aberration diagram of FIG. 2A, the vertical axis indicates the relative incident height, and the horizontal axis indicates the amount of aberration. The g-line with a wavelength of 436 nm is indicated as g, the F-line with a wavelength of 486 nm is indicated as F, the d-line with a wavelength of 588 nm is indicated as d, and the C-line with a wavelength of 656 nm is indicated as C.

4 of the second embodiment, FIG. 6 of the third embodiment, FIG. 8 of the fourth embodiment, FIG. 10 of the fifth embodiment, and FIG. 12 of the sixth embodiment. The display method is also the same display method as in FIG.

In the astigmatism diagram, the vertical axis indicates the object height or the incident angle, and the horizontal axis indicates the amount of aberration. In this specification, the solid line is the meridional image plane (M) and the dotted line is the sagittal image plane (S).

In addition, in FIG. 2(B) of the present embodiment, FIG. 4(B) of the second embodiment, and FIG. 6(B) of the third embodiment, the vertical axis is the object height, and FIG. B), FIG. 10B for the fifth embodiment, and FIG. 12B for the sixth embodiment, the vertical axis is the incident angle.

In the distortion diagrams, the vertical axis indicates the height of the object or the angle of incidence, and the horizontal axis indicates the amount of distortion in percent.

The distortion diagrams are displayed in FIG. 2(C) of this embodiment, FIG. 4(C) of the second embodiment, and FIG. 6(C) of the third embodiment. In FIG. 8(C) of the fourth embodiment, FIG. 10(C) of the fifth embodiment and FIG. 12(C) of the sixth embodiment, the vertical axis represents the incident angle.

As can be seen from FIGS. 2A to 2C, according to the immersion microscope objective lens of the present embodiment, excellent correction of chromatic aberration and excellent flatness of the image plane can be obtained.

(Second embodiment)
The immersion microscope objective lens of the second embodiment will be described with reference to FIGS. 3 and 4(A) to (C). FIG. 3 is a diagram showing an immersion microscope objective lens of a second embodiment according to the present invention.

The first lens group G1 includes, in order, a cemented lens of a plano-concave lens L11 and a biconvex lens L12, a positive meniscus lens L13 with a concave surface facing the object side, a positive meniscus lens L14 with a concave surface facing the object OBJ side, consists of

The second lens group G2 includes, in order from the object OBJ side, a cemented lens of a biconcave lens L21 and a biconvex lens L22, a cemented lens of a biconvex lens L23, a biconcave lens L24, and a biconvex lens L25, It is composed of a three-piece cemented lens consisting of a negative meniscus lens L26 with a convex surface facing toward the outside, a biconvex lens L27, and a biconcave lens L28.

The third lens group G3 is composed of a cemented lens of a biconvex lens L31 and a biconcave lens L32.
The fourth lens group G4 is composed of a biconcave lens L41.
The fifth lens group G5 is composed of a triple cemented lens consisting of a positive meniscus lens L51 with a concave surface facing the object side, a biconcave lens L52, and a biconvex lens L53.

The immersion microscope objective lens of this embodiment has a focal length f of 12.1 mm, a magnification of 16.5 times, an object-side NA of 0.8, a maximum object height of 0.75 mm, and a maximum image High Ih is 12.38 mm.

Table 2 below shows the data for this example.

Values corresponding to the conditions of this embodiment are shown below.
RDmax = 11.29
Ih/RDmax = 1.10
│(n6-n7)×f/R1 │=0.36
n1-n2=0.30
d/R3 = -1.00
(tan θ)/LL = 0.000767
|R4|/f=0.75
|R5|/f=1.63
|f4|/f=0.93
d3/t3 = 0.63
d4/t5 = 0.17

FIGS. 4A to 4C show various aberration diagrams of the immersion microscope objective lens of this embodiment. As can be seen from FIGS. 4A to 4C, according to the immersion microscope objective lens of the present embodiment, excellent correction of chromatic aberration and excellent flatness of the image plane can be obtained.

(Third embodiment)
The immersion microscope objective lens of the third embodiment will be described with reference to FIGS. 5 and 6(A) to (C). FIG. 5 is a diagram showing an immersion microscope objective lens of a third embodiment according to the present invention.

The first lens group G1 includes, in order, a three-piece cemented lens consisting of a plano-concave lens L11, a biconvex lens L12, and a positive meniscus lens L13 with a concave surface facing the object side, a positive meniscus lens L14 with a concave surface facing the object side, consists of

The second lens group G2 includes, in order, a cemented lens of a biconcave lens L21 and a biconvex lens L22, a cemented lens of a biconvex lens L23, a biconcave lens L24, and a biconvex lens L25, and a convex surface facing the object side. It is composed of a three-piece cemented lens consisting of a negative meniscus lens L26, a biconvex lens L27, and a biconcave lens L28.

The third lens group G3 is composed of a triplet cemented lens consisting of a biconvex lens L31, a biconcave lens L32, and a positive meniscus lens L33 having a convex surface facing the object side.
The fourth lens group G4 is composed of a biconcave lens L41.
The fifth lens group G5 is composed of a triple cemented lens consisting of a positive meniscus lens L51 with a concave surface facing the object side, a biconcave lens L52, and a biconvex lens L53.

The immersion microscope objective lens of this embodiment has a focal length f of 12.5 mm, a magnification of 16 times, an object-side NA of 0.8, a maximum object height of 0.75 mm, and a maximum image height Ih is 12.00 mm.

Table 3 below shows the data for this example.

Values corresponding to the conditions of this embodiment are shown below.
RDmax = 11.99
Ih/RDmax = 1.00
│(n6-n7)×f/R1 │=0.38
|(n4-n5)×f/R2 |=0.39
n1-n2=0.30
d/R3 = -0.64
(tan θ)/LL = 0.000747
|R4|/f=0.61
|R5|/f = 1.49
d3/t3 = 0.45
d4/t5 = 0.13

FIGS. 6A to 6C show various aberration diagrams of the immersion microscope objective lens of this embodiment. As can be seen from FIGS. 6A to 6C, according to the immersion microscope objective lens of the present embodiment, excellent correction of chromatic aberration and excellent flatness of the image plane can be obtained.

Fourth, fifth and sixth embodiments will be described below with reference to FIGS. 7 to 12. FIG. These examples are examples of imaging lenses.
Each embodiment is composed of a first lens group IG1, a second lens group IG2, and a third lens group IG3 in order from the object side.

(Fourth embodiment)
The imaging lens of the fourth embodiment will be described with reference to FIGS. 7 and 8(A) to (C). FIG. 7 is a diagram showing an imaging lens of a fourth embodiment according to the present invention.

The first lens group IG1 is composed of a cemented lens of a biconvex lens L1 and a biconcave lens L2.
The second lens group IG2 is composed of a positive meniscus lens L3 having a convex surface facing the object side.
The third lens group IG3 is composed of a cemented lens of a biconvex lens L4 and a biconcave lens L5.

The focal length fIm of the imaging lens of this embodiment is 200 mm. The distance Lp from the lens surface closest to the object to the pupil surface is -100 mm, the pupil diameter is 20 mm, and the maximum incident angle is 3 degrees.

Table 4 below shows the data for this example.

Values corresponding to the conditions of this embodiment are shown below.
Lp/fIm = -0.5
|fIm/f21|=0.68
|fIm/f22|=0.96
f23/fIm = -1.22
FIGS. 8A to 8C show various aberration diagrams of the imaging lens of this embodiment. As can be seen from FIGS. 8A to 8C, according to the imaging lens of this embodiment, good chromatic aberration correction is achieved and good flatness of the image plane is obtained.

(Fifth embodiment)
The imaging lens of the fifth embodiment will be described with reference to FIGS. 9 and 10(A) to (C). FIG. 9 is a diagram showing an imaging lens of a fifth embodiment according to the present invention.

The first lens group IG1 is composed of a cemented lens of a biconvex lens L1 and a biconcave lens L2.
The second lens group IG2 is composed of a positive meniscus lens L3 having a convex surface facing the object side.
The third lens group IG3 is composed of a cemented lens of a biconvex lens L4 and a biconcave lens L5.

The focal length fIm of the imaging lens of this embodiment is 200 mm. The distance Lp from the lens surface closest to the object to the pupil surface is -50 mm, the pupil diameter is 20 mm, and the maximum incident angle is 3 degrees.

Table 5 below shows the data for this example.

Values corresponding to the conditions of this embodiment are shown below.
Lp/fIm = -0.25
|fIm/f21|=0.70
|fIm/f22|=0.88
f23/fIm = -1.07

10A to 10C are various aberration diagrams of the imaging lens of this embodiment. As can be seen from FIGS. 10A to 10C, according to the imaging lens of this embodiment, good chromatic aberration correction is achieved and good flatness of the image plane is obtained.

(Sixth embodiment)
The imaging lens of the sixth embodiment will be described with reference to FIGS. 11 and 12(A) to (C). FIG. 11 is a diagram showing an imaging lens of a sixth embodiment according to the present invention.

The first lens group IG1 is composed of a cemented lens of a biconvex lens L1 and a negative meniscus lens L2 having a concave surface facing the object side.
The second lens group IG2 is composed of a positive meniscus lens L3 having a convex surface facing the object side.

The third lens group IG3 is composed of a cemented lens of a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
The focal length fIm of the imaging lens of this embodiment is 180 mm. The distance Lp from the lens surface closest to the object to the pupil surface is -120 mm, the pupil diameter is 18 mm, and the maximum incident angle is 4 degrees.

Table 6 below shows the data for this example.

Values corresponding to the conditions of this embodiment are shown below.
Lp/fIm = -0.67
|fIm/f21|=0.84
|fIm/f22|=0.87
f23/fIm = -0.74

12A to 12C show various aberration diagrams of the imaging lens of this embodiment. As can be seen from FIGS. 12A to 12C, according to the imaging lens of this embodiment, good chromatic aberration correction is achieved and good flatness of the image plane is obtained.

An embodiment of the microscope apparatus according to the present invention will be described below.
A microscope apparatus according to an embodiment of the present invention includes an illumination optical system for illuminating an object, an immersion microscope objective lens disclosed in the first to third embodiments for forming an image of the object, and It includes the imaging lens disclosed in the fourth through sixth embodiments and an observation system for observing an image.

As the illumination optical system, a near-infrared laser is used as a light source, and the near-infrared laser light is focused on the object by a lens. This causes the object to undergo two-photon excitation and emit visible light of various wavelengths.

Visible light of various wavelengths from an object is imaged by the immersion microscope objective lens disclosed in the first to third embodiments and the imaging lens disclosed in the fourth to sixth embodiments. An image is formed on the surface.

The observation system makes the formed image visible to the observer. A simple observation system has an eyepiece lens, and the observer directly observes with his/her eyes. For the observation system, it is particularly preferable to use an imaging device such as a CCD, a processing device such as a computer, and a display device such as an LED display. Furthermore, it may be recorded on a recording medium.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various modifications and changes are possible within the scope of the gist thereof.

G1 and IG1 First lens group G2 and IG2 Second lens group G3 and IG3 Third lens group G4 Fourth lens group G5 Fifth lens group L Lens C1 First bonding surface C2 Second bonding surface C3 First Appearing concave surface C4 having a negative refractive power Concave surface C5 of the cemented meniscus lens with a convex surface facing the object side of the third lens group Concave surface C5 of the cemented meniscus lens with a concave surface facing the object side of the fifth lens group OBJ Object

Claims (16)

From the object side,
A first lens group that has positive refractive power as a whole and is composed of two or more lenses;
a second lens group that has positive refractive power as a whole, includes a three-lens cemented lens, and is composed of seven or more lenses;
a third lens group composed of two or more lenses;
a fourth lens group having negative refractive power;
and a fifth lens group that is composed of two or more lenses and emits a parallel light beam,
The lenses that make up the first lens group are arranged closer to the object side than the lenses that make up the second lens group, and the lenses that make up the second lens group make up the third lens group. The lens that is arranged closer to the object than the lens and that constitutes the third lens group is arranged closer to the object than the lens that constitutes the fourth lens group, and the lens that constitutes the fourth lens group is , arranged closer to the object side than the lens constituting the fifth lens group,
At least one of the third lens group and the fifth lens group has a lens configuration of three or more lenses,
at least providing a cemented surface facing the object side in the third lens group, or providing a bonded surface facing the object side concavely in the fifth lens group,
When the maximum image height is Ih and the maximum effective radius of the lens is RDmax, and the first lens group has a bonding surface with a convex surface facing the object side, and a convex surface facing the object side. An immersion microscope objective lens, wherein the following conditions are satisfied, where n1 is the refractive index of a medium on the object side of a bonded surface and n2 is the refractive index of a medium on the opposite side .
0.35<Ih/RDmax<2.2
n1-n2>0.10 When the bonding surface facing the object side provided in the fifth lens group and facing the concave surface is defined as a first bonding surface, the first bonding surface has a positive refractive power,
Let n6 and n7 be the refractive indices of the media on both sides of the first bonded surface, R1 be the radius of curvature of the first bonded surface, and f be the focal length of the entire microscope objective lens system. 2. An immersion microscope objective lens according to claim 1, which satisfies the following conditions:
0.07 <｜(n6-n7)×f/R1 ｜< 1.2 The first lens group includes, in order from the object side, a negative lens, a biconvex lens, a first meniscus lens having a concave surface facing the object side, and a second meniscus lens having a concave surface facing the object side. 3. An immersion microscope objective lens according to claim 1 or 2, characterized by comprising : 3. The first meniscus lens having a concave surface facing the object side satisfies the following condition, where n3 is the refractive index of the first meniscus lens having a concave surface facing the object side. 3. The immersion microscope objective lens according to 3
n3 > 1.7 When the bonded surface provided in the third lens group and facing the convex surface facing the object side is used as a second bonded surface, the second bonded surface has a positive refractive power,
Let n4 and n5 be the refractive indices of the media on both sides of the second bonded surface, R2 be the radius of curvature of the second bonded surface, and f be the focal length of the entire microscope objective lens system. 5. The immersion microscope objective lens according to any one of claims 1 to 4 , wherein the following condition is satisfied.
0.07 <｜(n4-n5)×f/R2 ｜< 1.2 6. The immersion microscope objective lens according to claim 1 , wherein a lens surface closest to the object side of the first lens group is flat. 7. The immersion microscope objective lens according to any one of claims 1 to 6 , wherein said second lens group includes at least two cemented triplet lenses. an illumination optical system for illuminating an object;
an immersion microscope objective and an imaging lens according to any one of claims 1 to 7 for forming an image of the object;
and an observation system for observing the image. From the object side,
A first lens group that has positive refractive power as a whole and is composed of two or more lenses;
a second lens group that has positive refractive power as a whole, includes a three-lens cemented lens, and is composed of seven or more lenses;
a third lens group composed of two or more lenses;
a fourth lens group having negative refractive power;
and a fifth lens group that is composed of two or more lenses and emits a parallel light beam,
The lenses that make up the first lens group are arranged closer to the object side than the lenses that make up the second lens group, and the lenses that make up the second lens group make up the third lens group. The lens that is arranged closer to the object than the lens and that constitutes the third lens group is arranged closer to the object than the lens that constitutes the fourth lens group, and the lens that constitutes the fourth lens group is , arranged closer to the object side than the lens constituting the fifth lens group,
The first lens group includes, in order from the object side, a negative lens, a biconvex lens, a first meniscus lens having a concave surface facing the object side, and a second meniscus lens having a concave surface facing the object side. , consists of
At least one of the third lens group and the fifth lens group has a lens configuration of three or more lenses,
at least providing a cemented surface facing the object side in the third lens group, or providing a bonded surface facing the object side concavely in the fifth lens group,
An immersion microscope objective lens which satisfies the following conditions, where Ih is the maximum image height and RDmax is the maximum effective radius of the lens.
0.35<Ih/RDmax<2.2 When the bonding surface facing the object side provided in the fifth lens group and facing the concave surface is defined as a first bonding surface, the first bonding surface has a positive refractive power,
Let n6 and n7 be the refractive indices of the media on both sides of the first bonded surface, R1 be the radius of curvature of the first bonded surface, and f be the focal length of the entire microscope objective lens system. 10. The immersion microscope objective lens according to claim 9 , which satisfies the following conditions.
0.07 <｜(n6-n7)×f/R1 ｜< 1.2 3. The first meniscus lens having a concave surface facing the object side satisfies the following condition, where n3 is the refractive index of the first meniscus lens having a concave surface facing the object side. The immersion microscope objective lens according to 9 or 10
n3 > 1.7 The first lens group has a bonded surface with a convex surface facing the object side, and the refractive index of a medium on the object side of the bonded surface with the convex surface facing the object side is n1, and the medium on the opposite side has a refractive index of n1. The immersion microscope objective lens according to any one of claims 9 to 11 , wherein the following conditions are satisfied, where n2 is the refractive index of
n1-n2>0.10 When the bonded surface provided in the third lens group and facing the convex surface facing the object side is used as a second bonded surface, the second bonded surface has a positive refractive power,
Let n4 and n5 be the refractive indices of the media on both sides of the second bonded surface, R2 be the radius of curvature of the second bonded surface, and f be the focal length of the entire microscope objective lens system. 13. The immersion microscope objective lens according to any one of claims 9 to 12 , which satisfies the following condition.
0.07 <｜(n4-n5)×f/R2 ｜< 1.2 14. The immersion microscope objective lens according to any one of claims 9 to 13 , wherein a lens surface closest to the object side of the first lens group is flat. 15. The immersion microscope objective lens according to any one of claims 9 to 14 , wherein said second lens group includes at least two triplet cemented lenses. an illumination optical system for illuminating an object;
an immersion microscope objective and imaging lens according to any one of claims 9 to 15 for forming an image of said object;
and an observation system for observing the image.

Images