JPH11352407A - Microscopic objective lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a microscopic objective lens which is well corrected of both of chromatic aberration and various aberrations over a wide wavelength range from a visible light region to a near UV region by setting the focal length of a first lens group, the focal length of a second lens group and the focal length of the entire system of the microscopic objective lens so as to satisfy specific conditions. SOLUTION: When the focal length of the first lens group G1 is defined as f1, the focal length of the second lens group G2 as f2 and the focal length of the entire system of the microscopic objective lens as fT, the equations; 1<f1/fT<20, 0.5<f2/fT<5 are satisfied. The parameters of the respective lens groups G1, G2 are so set as to simultaneously satisfy these condition equations, by which the various aberrations, such as spherical aberrations, coma aberrations and chromatic aberrations, are simultaneously well corrected over the wide wavelength range from the near UV region to the visible region. Then, the optical system adequate for printing, microprocessing of IC patterns and high resolution observation is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope objective lens, and more particularly, to a microscope objective lens suitable for printing an IC pattern, fine processing, and high-resolution observation.

[0002]

2. Description of the Related Art A conventional optical system is disclosed in
No. 5811 discloses that the magnification is 20 times and the numerical aperture is 0.7.
5, a microscope objective with a working distance of 0.7 mm is disclosed. Japanese Patent Application Laid-Open No. 4-159506 discloses that the magnification is 10 to 20 times and the numerical aperture is 0.3 to 0.4.
5, there is disclosed a microscope objective lens having a working distance of about 3 mm to 11 mm and aberration correction of a semi-apochromat class or an apochromat class.

[0003]

However, the above-mentioned Japanese Patent Application Laid-Open No. 61-275811 and Japanese Patent Application Laid-Open No.
Based on the configuration disclosed in Japanese Patent Publication No. 9506, a magnification of 1
About 0 times, numerical aperture is about 0.25, working distance is 10
mm or more, and even if an attempt is made to realize a microscope objective lens in which aberrations are satisfactorily corrected from the visible light region to the near-ultraviolet light region, chromatic aberration and various aberrations cannot be satisfactorily corrected at the same time. There was a disadvantage that an image could not be obtained.

The present invention has been made in view of the above problems, and has a magnification of about 10 times, a numerical aperture of about 0.3, and covers a wide wavelength range from the visible light region to the near ultraviolet light region. It is an object of the present invention to provide a microscope objective lens in which both chromatic aberration and various aberrations are well corrected.

[0005]

In order to solve the above-mentioned problems, according to the present invention, at least two objects are sequentially arranged from the object side.
A first lens group G1 having two cemented surfaces and having a positive refractive power as a whole, a second lens group G2 having at least one cemented surface and having a positive refractive power as a whole, and at least one joint surface. In a microscope objective lens including a third lens group G3 having a first lens group G3 and a fourth lens group G4 having at least one cemented surface, the focal length of the first lens group G1 is f1, and the focal length of the second lens group G2 is Distance to f2
And a microscope objective lens characterized by satisfying the following condition: 1 <f1 / fT <20 0.5 <f2 / fT <5, where fT is the focal length of the entire microscope objective lens system.

According to a preferred aspect of the present invention, the third
When the focal length of the lens group G3 is f3 and the focal length of the entire microscope objective lens system is fT, the following condition is satisfied: 1 <| f3 | / fT <150. When the focal length of the fourth lens group G4 is f4 and the focal length of the entire microscope objective is fT, it is preferable that the following condition is satisfied: 0.5 <| f4 | / fT <7.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, a second harmonic (wavelength λ = 532 nm) of a YAG laser is used as a laser beam used for baking or fine processing of an IC pattern and high-resolution observation.
Or the third harmonic of a YAG laser (wavelength λ = 355 nm)
Or the fourth harmonic of a YAG laser (wavelength λ = 266 nm)
Etc. Optical materials that can transmit these short-wavelength laser beams satisfactorily are limited to, for example, fluorite and quartz. An optical system that allows observation in the visible light region (visible wavelength region) and near ultraviolet light region (near ultraviolet wavelength region) using only these two types of optical materials, and enables laser processing using near ultraviolet light. Is difficult to design as long as there are constraints on the overall length of the optical system, transmission characteristics, and the like.

However, as disclosed in Japanese Patent Application Laid-Open No. 6-347700, for example, it has been found that design is feasible when a diffractive optical element (DOE) is used. In the present invention, by employing the above-described configuration, laser processing using the near ultraviolet region and normal observation using visible light can be performed without using a diffractive optical element or the like and without deteriorating various aberrations. A microscope objective lens whose chromatic aberration is well corrected so that it can be performed is realized.

Hereinafter, the conditional expression of the present invention will be described.
In the present invention, the following conditional expressions (1) and (2) are satisfied. 1 <f1 / fT <20 (1) 0.5 <f2 / fT <5 (2) where f1 is a focal length of the first lens group G1, and f
2 is the focal length of the second lens group G2, and fT is the focal length of the entire microscope objective lens system.

Conditional expression (1) defines an appropriate range for the focal length of the first lens group G1 having a positive refractive power as a whole. In other words, the conditional expression (1) satisfies the condition that the divergent light flux from the object surface is appropriately converged by the first lens group G1 to correct spherical aberration and coma aberration,
The following conditional expressions are used to limit the effective diameter of each lens unit so that it does not become too large. The second lens group G
In order to balance the chromatic aberration correction in each of the second and subsequent lens groups, the chromatic aberration correction is set to an insufficient state in the first lens group G1.

When the value exceeds the upper limit of conditional expression (1), the convergence of the first lens group G1 becomes weak, and the height of the axial ray entering the lens system becomes large, so that a large spherical aberration occurs. Resulting in. On the other hand, when the value goes below the lower limit of conditional expression (1), the positive refracting power of the first lens group G1 becomes too strong, so that it becomes difficult to satisfactorily correct spherical aberration, coma, and the like. In order to further improve the optical performance of the microscope objective according to the present invention, it is desirable to set the upper limit of conditional expression (1) to 14.

Conditional expression (2) defines an appropriate range for the focal length of the second lens group G2 having a positive refractive power as a whole. In other words, the conditional expression (2) satisfies various aberrations while further converging the light beam from the first lens group G1 by the second lens group G2 and guiding the light beams to the third lens group G3 and the fourth lens group G4. 6 is a conditional expression for favorably correcting chromatic aberration while favorably correcting.

When the value exceeds the upper limit of conditional expression (2), the positive refractive power of the second lens unit G2 becomes too weak, and the height of the light ray incident on the third lens unit G3 becomes large. Good correction becomes difficult. On the other hand, when the value goes below the lower limit of conditional expression (2), the spherical aberration generated by the second lens group G2 increases, and it becomes difficult to satisfactorily correct the spherical aberration by another lens group. Further, the second lens group G2 balances the chromatic aberration correction with the other lens groups. However, if the value deviates from the range of the conditional expression (2), the chromatic aberration correction balance is lost. It will be difficult.

In the present invention, it is desirable to satisfy the following conditional expression (3). 1 <| f3 | / fT <150 (3) where f3 is the focal length of the third lens group G3, and f
T is the focal length of the entire microscope objective lens system.

Condition (3) defines an appropriate range for the focal length of the third lens group G3. In other words,
Conditional expression (3) defines a third lens group G3 and a fourth lens group in order to correct the positive Petzval sum generated in the first lens group G1 and the second lens group G2 to reduce the Petzval sum as a whole. This is a conditional expression for generating a negative Petzval sum with a negative refractive power by double Gaussian of G4. The conditional expression is for guiding the light beam to the fourth lens group G4 while favorably correcting axial chromatic aberration and spherical aberration from the first lens group G1 to the third lens group G3.

When the value exceeds the upper limit of conditional expression (3), the refractive power of the third lens unit G3 becomes too weak, the Petzval sum is insufficiently corrected, and the flatness of the image surface deteriorates. Further, the first lens group G1 and the second lens group G
The balance between the positive refracting power constituted by 2 and the refracting power of the third lens group G3 is lost, and spherical aberration and axial chromatic aberration are undesirably deteriorated. On the other hand, when the value goes below the lower limit value of the conditional expression (3), the refractive power of the third lens group G3 becomes too strong, and the height of the light ray incident on the fourth lens group G4 changes. As a result, the balance between the spherical aberration generated by the first lens group G1 to the third lens group G3 and the spherical aberration generated by the fourth lens group G4 is undesirably lost.

In the present invention, it is desirable that the following conditional expression (4) is satisfied. 0.5 <| f4 | / fT <7 (4) where f4 is the focal length of the fourth lens group G4, and f
T is the focal length of the entire microscope objective lens system.

Conditional expression (4) defines an appropriate range for the focal length of the fourth lens group G4. In other words,
Conditional expression (4) indicates that the first lens group G1 to the third lens group G
3 is a conditional expression for favorably correcting field curvature without deteriorating spherical aberration and axial chromatic aberration appropriately corrected in 3. Similarly to the conditional expression (3), the conditional expression (4) is a conditional expression for reducing the whole Petzval sum of the pair of the third lens group G3 and the fourth lens group G4.

When the value exceeds the upper limit of conditional expression (4), the refractive power of the fourth lens unit G4 becomes too weak, the Petzval sum is insufficiently corrected, and the flatness of the image surface deteriorates. In addition, it is not preferable because spherical aberration, coma aberration and the like are largely generated. On the other hand, when the value goes below the lower limit of conditional expression (4), the refracting power of the fourth lens unit G4 becomes too strong, and the coma generated in the fourth lens unit G4 can be favorably corrected by the other lens units. It is not preferable because it becomes possible.

In the present invention, it is desirable that the following conditional expression (5) is satisfied. 0.05 <D3 / fT <0.7 (5) where D3 is an axial air gap between the third lens group G3 and the fourth lens group G4, and fT is a focal point of the entire microscope objective lens system. Distance.

Conditional expression (5) defines an appropriate range for the ratio of the on-axis air gap D3 between the third lens group G3 and the fourth lens group G4 to the focal length fT of the entire microscope objective lens system. I have. When the value goes below the lower limit of conditional expression (5), it becomes difficult to satisfactorily correct chromatic aberration of magnification, and large spherical aberration and coma occur.
On the other hand, when the value exceeds the upper limit value of the conditional expression (5), the height of the light ray incident on the fourth lens group G4 becomes too large, and a large coma aberration is generated. In addition, the Petzval sum is insufficiently corrected, and the flatness of the image surface deteriorates, which is not preferable.

In the present invention, the second lens group G
It is desirable that 2 has a triplet cemented lens composed of one negative lens and two positive lenses bonded together, and satisfies the following conditional expressions (6) and (7). 0.04 <N2n-N2p1 (6) 0.04 <N2n-N2p2 (7) Here, N2n is a refractive index for a wavelength of 532 nm of one negative lens in the three cemented lenses of the second lens group G2. is there. N2p1 and N2p2 are the refractive indices of the two positive lenses in the triplet of the second lens group G2 with respect to the wavelength of 532 nm.

Conditional expressions (6) and (7) define the relationship between the refractive indices of the lenses constituting the triplet in the second lens group G2. By satisfying conditional expressions (6) and (7), not only axial chromatic aberration can be corrected well, but also spherical aberration and coma can be corrected with good balance. Conversely, if conditional expressions (6) and (7) are not satisfied, the radius of curvature of the cemented surface of the triplet lens must be increased. As a result, high-order spherical aberration occurs, and it becomes difficult to satisfactorily correct the high-order spherical aberration with another lens group, which is not preferable. in this case,
In particular, it becomes difficult to correct aberrations in a short wavelength region.

When the second lens group G2 has the three cemented lens described above, it is desirable that the following conditional expressions (8) to (11) are further satisfied. 10 <ν2p1−ν2n (8) 10 <ν2p2−ν2n (9) 90 <ν2p1 (10) 90 <ν2p2 (11) Here, ν2n is one negative lens in the triplet of the second lens group G2. This is the Abbe number for the d-line of the lens. Further, ν2p1 and ν2p2 are Abbe numbers of the two positive lenses in the triplet of the second lens group G2 with respect to the d-line.

The conditional expressions (8) and (9) define the relationship between the Abbe numbers of the lenses forming the triplet in the second lens group G2. If conditional expressions (8) and (9) are not satisfied, in order to satisfactorily correct chromatic aberration, the refractive power of the positive lens and the refractive power of the negative lens become too strong, and high-order aberrations such as spherical aberration and coma aberration are caused. It is not preferable because it occurs. In order to reduce these higher-order aberrations, the number of lenses must be increased, resulting in a significant increase in costs such as polishing and adjustment.

On the other hand, conditional expressions (10) and (11) satisfy the second condition.
An appropriate range is defined for the Abbe number of the two positive lenses that make up the three-element cemented lens in the lens group G2. If conditional expressions (10) and (11) are not satisfied, large spherical aberration and chromatic aberration occur in the short wavelength region and the visible wavelength region, and it is difficult to satisfactorily correct chromatic aberration and various aberrations simultaneously at each wavelength. Is not preferred.

In the present invention, the fourth lens group G
It is desirable that reference numeral 4 has a three-element cemented lens formed by bonding one negative lens and two positive lenses, and satisfies the following conditional expressions (12) and (13). 0.04 <N4n-N4p1 (12) 0.04 <N4n-N4p2 (13) Here, N4n is a refractive index for a wavelength of 532 nm of one negative lens in the three cemented lenses of the fourth lens group G4. is there. N4p1 and N4p2 are the refractive indexes of the two positive lenses in the triplet of the fourth lens group G4 with respect to the wavelength of 532 nm.

The conditional expressions (12) and (13) define the relationship between the refractive indices of the lenses constituting the triplet in the fourth lens group G4. As in the case of the conditional expressions (6) and (7), by satisfying the conditional expressions (12) and (13), not only the axial chromatic aberration can be favorably corrected, but also the spherical aberration and the coma aberration can be improved. Can be corrected in a well-balanced manner. Conversely, if conditional expressions (12) and (13) are not satisfied, the radius of curvature of the cemented surface of the triplet lens must be increased. As a result, high-order spherical aberration occurs, and it becomes difficult to satisfactorily correct the high-order spherical aberration with another lens group, which is not preferable.

When the fourth lens group G4 includes the three cemented lenses described above, it is preferable that the following conditional expressions (14) to (17) are further satisfied. 10 <ν4p1−ν4n (14) 10 <ν4p2−ν4n (15) 90 <ν4p1 (16) 90 <ν4p2 (17) Here, ν4n is one negative lens in the triplet of the fourth lens group G4. This is the Abbe number for the d-line of the lens. Ν4p1 and ν4p2 are Abbe numbers of the two positive lenses in the fourth cemented lens of the fourth lens group G4 with respect to the d-line.

The conditional expressions (14) and (15) define the relationship between the Abbe numbers of the lenses constituting the triplet in the fourth lens group G4. As in the case of the conditional expressions (8) and (9), when the conditional expressions (14) and (15) are not satisfied, the refractive power of the positive lens and the refractive power of the negative lens are strong when the chromatic aberration is corrected. It is not preferable because it becomes too much and high-order aberrations occur in spherical aberration, coma and the like. In order to reduce these higher-order aberrations, the number of lenses must be increased, resulting in a significant increase in costs such as polishing and adjustment.

On the other hand, conditional expressions (16) and (17) satisfy the fourth condition.
An appropriate range is defined for the Abbe number of the two positive lenses forming the triplet in the lens group G4. As in the case of the conditional expressions (10) and (11), when conditional expressions (16) and (17) are not satisfied, large spherical aberration and chromatic aberration occur in the short wavelength region and the visible wavelength region. It is not preferable because it becomes difficult to satisfactorily correct chromatic aberration and various aberrations simultaneously at the wavelength.

On the object side of the microscope objective lens of the present invention,
A parallel plane plate made of synthetic quartz or sapphire is incorporated. The parallel flat plate functions as a shield for protecting the lens from debris generated in the microfabrication process, or a polymer material such as a protective film on the IC surface or an insulating film between multilayer substrates, which is vaporized by a photochemical reaction. If the objective lens is used for a long time, fragments generated in the fine processing process may adhere to the lens, and the light intensity may be reduced, so that the fine processing may not be performed efficiently. . As a countermeasure, as shown in FIG. 14, on the object side of the microscope objective lens 1 of the present invention, a plurality of parallel flat plates 2 made of synthetic quartz or sapphire are incorporated into a rotating disk 3, and the rotating disk 3 is driven by a driving system 4. By switching the plane-parallel plate 2 with respect to the microscope objective lens 1 at regular intervals of rotation, fine processing can be performed efficiently.

Further, in order to automatically switch the plane-parallel plate 2, the light beam from the light source 6 via the half mirror 5 may be made incident on a part of the plane-parallel plate 2 as shown in FIG. it can. In this case, the light transmitted through the plane-parallel plate 2 is monitored by a detector 8 via a lens 7, and the light reflected by the plane-parallel plate 2 is monitored by a detector 10 via a lens 9. In this way, when the light intensity detected by the detector 8 becomes smaller than a certain value or when the light intensity detected by the detector 10 becomes higher than a certain value, the plurality of parallel flat plates 2 are assembled. The rotated rotating disk 3 is rotated by the action of the drive system 4, so that the plane-parallel plate 2 can be automatically switched with respect to the microscope objective lens 1.

[0034]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In each embodiment, the microscope objective lens of the present invention includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power,
The third lens group G3 and the fourth lens group G4 are provided.

In each embodiment, since the microscope objective lens is designed to be an infinity system, an imaging lens (second objective lens) is arranged on the image side of the microscope objective lens with an on-axis air gap of 80 mm. A finite optical system is formed by a combination of a microscope objective lens and an imaging lens. The various aberration diagrams shown in each of the following examples are various aberration diagrams when the axial air gap between the microscope objective lens and the imaging lens is 80 mm. However, the present inventors have verified that even if the on-axis air gap changes to some extent, there is almost no change in aberration.

FIG. 13 is a diagram showing the configuration of the imaging lens in each embodiment. As shown in FIG. 13, the imaging lens in each example includes, in order from the object side, a cemented lens G5 of a biconcave lens and a biconvex lens, and a biconvex lens G6. Table 1 below summarizes the data values of the imaging lens in each example. In Table (1), the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d indicates the distance between the lens surfaces, and n532 indicates the refractive index for visible light having a wavelength of 532.0 nm. Nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is d
Abbe numbers for the line (λ = 587.6 nm) are shown.

[0037]

[Table 1] Surface number rd n532 nd ν 1 -30.60 2.00 1.46075 1.45850 67.8 (G5) 2 2406.00 5.00 1.43537 1.43385 95.2 3 -39.10 1.00 4 417.40 5.00 1.43537 1.43385 95.2 (G6) 5 -51.90

[First Embodiment] FIG. 1 is a view showing a configuration of a microscope objective lens according to a first embodiment of the present invention. In the microscope objective lens of FIG. 1, the first lens group G1 includes:
It comprises, in order from the object side, a parallel plane plate L1, a cemented lens of a biconcave lens L2 and a biconvex lens L3, and a cemented lens of a biconcave lens L4 and a biconvex lens L5.

The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 and a biconvex lens L7 having a convex surface facing the object side, and a biconvex lens L8, a biconcave lens L9, and a convex surface facing the object side. And a three-element cemented lens with a positive meniscus lens L10. Further, the third lens group G3 is composed of a cemented lens of a biconvex lens L11 and a biconcave lens L12 in order from the object side. The fourth lens group G4 includes, in order from the object, a cemented lens formed by a biconcave lens L13 and a biconvex lens L14, and a positive meniscus lens L15 having a convex surface facing the object.

Table 2 below summarizes data values of the first embodiment of the present invention. In Table (2), fT is wavelength 532
The focal length of the entire system (objective lens only) at infinity focusing on visible light of nm, NA is the numerical aperture on the object side, β is the magnification when the imaging lens is used, and WD is the working distance ( The axial distance between the object plane and the lens surface closest to the object side of the objective lens)
Respectively. Further, the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d
Is the distance between the lens surfaces, n532 is the refractive index for visible light having a wavelength of 532 nm, nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is the d line (λ = 587.6n).
m), respectively.

[0041]

[Table 2] fT = 20.05 NA = 0.25 β = 10 × WD = 8.8 Surface number rd n532 nd ν 1 ∞ 0.50 1.46075 1.45850 67.8 L1 2 ∞ 2.20 3 -629.432 1.00 1.46075 1.45850 67.8 L2 4 11.684 4.80 1.43537 1.43385 95.2 L3 5 -9.659 1.70 6 -8.261 1.00 1.46075 1.45850 67.8 L4 7 43.607 4.12 1.43537 1.43385 95.2 L5 8 -16.263 0.10 9 22.695 1.00 1.46075 1.45850 67.8 L6 10 12.308 6.55 1.43537 1.43385 95.2 L7 11 -18.945 0.10 12.139 1.43385 95.2 L8 13 -19.961 1.00 1.47642 1.47449 81.6 L9 14 5.855 3.75 1.43537 1.43385 95.2 L10 15 8.370 0.51 16 8.373 3.61 1.43537 1.43385 95.2 L11 17 -88.899 2.44 1.46075 1.45850 67.8 L12 18 7.281 2.67 19 -5.266 3.02 1.46075 1.45850.824.20 20 1.43537 1.43385 95.2 L14 21 -7.959 1.00 22 26.141 2.00 1.46075 1.45850 67.8 L15 23 242.359 2.00 (Values for conditional expressions) (1) f1 / fT = 2.725 (2) f2 / fT = 1.159 (3) | f3 | /FT=2.348 (4) | F4 | / fT = 8.847 (5) D3 / fT = 0.133 (6) N2n-N2p1 = 0.04105 (L8 and L9) (7) N2n-N2p2 = 0.04105 (L10 and L9) ( 8) v2p1-v2n = 13.6 (L8 and L9) (9) v2p2-v2n = 13.6 (L10 and L9) (10) v2p1 = 95.2 (L8) (11) v2p2 = 95.2 (L10) )

FIG. 2 is a diagram showing various aberrations in the first embodiment. In each aberration diagram, NA is the numerical aperture, Y is the image height,
Solid line A represents visible light with a wavelength of 532.0 nm, and dotted line C represents C
Line (λ = 656.3 nm), and the dashed line F indicates the F line (λ = 656.3 nm).
486.1 nm), and the dashed line B indicates a near ultraviolet ray having a wavelength of 266.0 nm. In the astigmatism diagrams, S indicates a sagittal image plane, and T indicates a meridional image plane. As is clear from the aberration diagrams, in the first embodiment, various aberrations are favorably corrected over a wide wavelength range from 266 nm to 656.3 nm, and excellent optical performance is secured. In Table (2) (values corresponding to the conditional expressions), the values of the conditional expressions (6) and (7) are not the refractive index for the d-line but the wavelength 532.
It is calculated based on the refractive index for visible light of nm. However, in the first embodiment, it goes without saying that the conditional expressions (6) and (7) are satisfied based on the refractive index for the d-line.

[Second Embodiment] FIG. 3 is a view showing a configuration of a microscope objective lens according to a second embodiment of the present invention. In the microscope objective lens of FIG. 3, the first lens group G1 is
It comprises, in order from the object side, a parallel plane plate L1, a cemented lens of a biconcave lens L2 and a biconvex lens L3, and a cemented lens of a biconcave lens L4 and a biconvex lens L5.

The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 and a biconvex lens L7 with the convex surface facing the object side, and a biconvex lens L8, a biconcave lens L9, and a biconvex lens L10. A triple cemented lens, a negative meniscus lens L11 and a biconvex lens L12 having a convex surface facing the object side, and a positive meniscus lens L having a concave surface facing the object side
13 and three cemented lenses. Further, the third lens group G3 includes, in order from the object side, a cemented lens of a positive meniscus lens L14 having a convex surface facing the object side and a negative meniscus lens L15 having a convex surface facing the object side. The fourth lens group G4 includes, in order from the object side, a negative meniscus lens L16 having a concave surface facing the object side and a negative meniscus lens L17 having a convex surface facing the object side.

Table 3 below summarizes data values of the second embodiment of the present invention. In Table (3), fT is the wavelength 532
The focal length of the entire system (objective lens only) at infinity focusing on visible light of nm, NA is the numerical aperture on the object side, β is the magnification when the imaging lens is used, and WD is the working distance ( The axial distance between the object plane and the lens surface closest to the object side of the objective lens)
Respectively. Further, the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d
Is the distance between the lens surfaces, n532 is the refractive index for visible light having a wavelength of 532 nm, nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is the d line (λ = 587.6n).
m), respectively.

[0046]

Table 3 fT = 19.66 NA = 0.25 β = 10 × WD = 8.8 Surface number rd n532 nd v 1 1 0.50 1.46075 1.45850 67.8 L1 2 2 2.16 3 -20.227 1.00 1.46075 1.45850 67.8 L2 4 10.595 4.93 1.43537 1.43385 95.2 L3 5 -7.149 1.93 6 -6.810 1.00 1.46075 1.45850 67.8 L4 7 49.223 3.54 1.43537 1.43385 95.2 L5 8 -18.040 0.10 9 306.730 1.00 1.46075 1.45850 67.8 L6 10 33.226 3.66 1.43537 1.43385 95.2 L7 11 -31.32093.71 12.435 1.43385 95.2 L8 13 -24.439 1.00 1.47642 1.47449 81.6 L9 14 17.567 5.12 1.43537 1.43385 95.2 L10 15 -29.933 0.10 16 37.722 1.00 1.46075 1.45850 67.8 L11 17 21.188 4.28 1.43537 1.43385 95.2 L12 18 -48.821 2.56 1.46075 1.45850 67.80.12 22.52.0 4.07 1.43537 1.43385 95.2 L14 21 32.567 1.00 1.46075 1.45850 67.8 L15 22 20.219 2.18 23 -20.331 5.07 1.46075 1.45850 67.8 L16 24 -51.950 0.10 25 40.483 1.00 1.46075 1.45850 67.8 L17 26 14.759 82.00 (Values for conditional expressions) (1) f1 / fT = 13.471 (2) f2 / fT = 0.965 (3) | f3 | /fT=36.356 (4) | f4 | /fT=1.356 (5) D3 / fT = 0.111 (6) N2n-N2p1 = 0.04105 (L8 and L9) (7) N2n-N2p2 = 0.04105 (L10 and L9) (8) ν2p1-ν2n = 13.6 (L8 and L9) (9) ν2p2-ν2n = 13.6 ( L10 and L9) (10) ν2p1 = 95.2 (L8) (11) ν2p2 = 95.2 (L10)

FIG. 4 is a diagram showing various aberrations in the second embodiment. In each aberration diagram, NA is the numerical aperture, Y is the image height,
Solid line A represents visible light with a wavelength of 532.0 nm, and dotted line C represents C
Line (λ = 656.3 nm), and the dashed line F indicates the F line (λ = 656.3 nm).
486.1 nm), and the dashed line B indicates a near ultraviolet ray having a wavelength of 266.0 nm. In the astigmatism diagrams, S indicates a sagittal image plane, and T indicates a meridional image plane. As is clear from the aberration diagrams, in the second embodiment, various aberrations are favorably corrected over a wide wavelength range from 266 nm to 656.3 nm, and excellent optical performance is secured. In Table (3) (values corresponding to the conditional expressions), the values of the conditional expressions (6) and (7) are not the refractive index for the d-line but the wavelength 532.
It is calculated based on the refractive index for visible light of nm. However, in the second embodiment, it goes without saying that the conditional expressions (6) and (7) are satisfied based on the refractive index for the d-line.

[Third Embodiment] FIG. 5 is a view showing a configuration of a microscope objective lens according to a third embodiment of the present invention. In the microscope objective lens of FIG. 5, the first lens group G1 includes:
It comprises, in order from the object side, a parallel plane plate L1, a cemented lens of a biconcave lens L2 and a biconvex lens L3, and a cemented lens of a biconcave lens L4 and a biconvex lens L5.

The second lens group G2 includes, in order from the object side, a cemented lens of a negative meniscus lens L6 having a convex surface facing the object side and a biconvex lens L7, a cemented lens of a biconcave lens L8 and a biconvex lens L9, and It is composed of a three-element cemented lens of a negative meniscus lens L10 having a convex surface facing the object side, a biconvex lens L11, and a biconcave lens L12. further,
The third lens group G3 includes, in order from the object side, a negative meniscus lens L13 having a convex surface facing the object side, a negative meniscus lens L14 having a convex surface facing the object side, and a negative meniscus lens L15 having a convex surface facing the object side. It is composed of a cemented lens. The fourth lens group G4 includes, in order from the object side, a three-element cemented lens composed of a positive meniscus lens L16 having a concave surface facing the object side, a biconcave lens L17, and a biconvex lens L18, and a negative meniscus having a convex surface facing the object side. It is composed of a lens L19.

Table 4 below summarizes the data values of the third embodiment of the present invention. In Table (4), fT is the wavelength 532
The focal length of the entire system (objective lens only) at infinity focusing on visible light of nm, NA is the numerical aperture on the object side, β is the magnification when the imaging lens is used, and WD is the working distance ( The axial distance between the object plane and the lens surface closest to the object side of the objective lens)
Respectively. Further, the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d
Is the distance between the lens surfaces, n532 is the refractive index for visible light having a wavelength of 532 nm, nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is the d line (λ = 587.6n).
m), respectively.

[0051]

Table 4 fT = 20.05 NA = 0.25 β = 10 × WD = 9.8 Surface number rd n532 nd ν 1 1 0.50 1.46075 1.45850 67.8 L1 2 1 1.20 3 -35.549 1.00 1.46075 1.45850 67.8 L2 4 15.280 4.63 1.43537 1.43385 95.2 L3 5 -7.813 1.50 6 -7.885 1.00 1.46075 1.45850 67.8 L4 7 54.754 3.59 1.43537 1.43385 95.2 L5 8 -16.580 0.10 9 44.319 1.00 1.46075 1.45850 67.8 L6 10 35.267 3.97 1.43537 1.43385 95.2 L7 11 -19.481 0.10 12 1.46075 1.45850 67.8 L8 13 21.710 3.77 1.43537 1.43385 95.2 L9 14 -36.486 0.10 15 37.999 1.00 1.46075 1.45850 67.8 L10 16 14.233 3.63 1.43537 1.43385 95.2 L11 17 -358.405 1.00 1.46075 1.45850 67.8 L12 18 472.763 0.10 19 24.396 1.00 1.46075 1.45 2.45 1.43537 1.43385 95.2 L14 21 17.138 1.00 1.46075 1.45850 67.8 L15 22 16.864 2.77 23 -9.906 2.79 1.43537 1.43385 95.2 L16 24 -7.563 2.29 1.47642 1.47449 81.6 L17 25 51.802 4.08 1.43537 1.43385 95.2 L18 26 -12.427 0.10 27 12.962 5.50 1.46075 19.4558 67.8 3 80.00 (Values corresponding to conditional expressions) (1) f1 / fT = 4.221 (2) f2 / fT = 1.126 (3) | f3 | /fT=7.123 (4) | f4 | / fT = 5 .336 (5) D3 / fT = 0.138 (12) N4n-N4p1 = 0.04105 (L16 and L17) (13) N4n-N4p2 = 0.04105 (L18 and L17) (14) ν4p1-ν4n = 13 0.6 (L16 and L17) (15) ν4p2 −ν4n = 13.6 (L18 and L17) (16) ν4p1 = 95.2 (L16) (17) ν4p2 = 95.2 (L18)

FIG. 6 is a diagram showing various aberrations in the third embodiment. In each aberration diagram, NA is the numerical aperture, Y is the image height,
Solid line A represents visible light with a wavelength of 532.0 nm, and dotted line C represents C
Line (λ = 656.3 nm), and the dashed line F indicates the F line (λ = 656.3 nm).
486.1 nm), and the dashed line B indicates a near ultraviolet ray having a wavelength of 266.0 nm. In the astigmatism diagrams, S indicates a sagittal image plane, and T indicates a meridional image plane. As is clear from the aberration diagrams, in the third embodiment, various aberrations are favorably corrected over a wide wavelength range from 266 nm to 656.3 nm, and excellent optical performance is secured. In Table (4) (values corresponding to the conditional expressions), the values of the conditional expressions (12) and (13) are not the refractive index for the d-line but the wavelength 532.
It is calculated based on the refractive index for visible light of nm. However, in the third embodiment, it goes without saying that the conditional expressions (12) and (13) are satisfied based on the refractive index for the d-line.

[Fourth Embodiment] FIG. 7 is a view showing a configuration of a microscope objective lens according to a third embodiment of the present invention. In the microscope objective lens of FIG. 7, the first lens group G1 includes:
It comprises, in order from the object side, a parallel plane plate L1, a cemented lens of a biconcave lens L2 and a biconvex lens L3, and a cemented lens of a biconcave lens L4 and a biconvex lens L5.

The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 having a convex surface facing the object side and a biconvex lens L7, and a biconvex lens L8, a biconcave lens L9, and a biconvex lens L10. It is composed of a triple cemented lens and a triple cemented lens of a negative meniscus lens L11 having a convex surface facing the object side, a biconvex lens L12, and a biconcave lens L13. Further, the third lens group G3 includes, in order from the object side, a cemented lens of a positive meniscus lens L14 having a convex surface facing the object side and a negative meniscus lens L15 having a convex surface facing the object side. The fourth lens group G4
Are, in order from the object side, a positive meniscus lens L16 having a concave surface facing the object side, a negative meniscus lens L17 having a concave surface facing the object side, and a positive meniscus lens L18 having a concave surface facing the object side.
And a negative meniscus lens L19 having a convex surface facing the object side.

Table 5 below summarizes the data values of the fourth embodiment of the present invention. In Table (5), fT is wavelength 532
The focal length of the entire system (objective lens only) at infinity focusing on visible light of nm, NA is the numerical aperture on the object side, β is the magnification when the imaging lens is used, and WD is the working distance ( The axial distance between the object plane and the lens surface closest to the object side of the objective lens)
Respectively. Further, the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d
Is the distance between the lens surfaces, n532 is the refractive index for visible light having a wavelength of 532 nm, nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is the d line (λ = 587.6n).
m), respectively.

[0056]

Table 5 fT = 20.02 NA = 0.30 β = 10 × WD = 9.8 Surface number rd n532 nd ν 1 ∞ 0.50 1.46075 1.45850 67.8 L1 2 ∞ 1.16 3 -24.345 1.00 1.46075 1.45850 67.8 L2 4 18.356 5.32 1.43537 1.43385 95.2 L3 5 -8.342 1.50 6 -8.481 1.00 1.46075 1.45850 67.8 L4 7 107.105 4.01 1.43537 1.43385 95.2 L5 8 -18.184 0.10 9 63.997 1.00 1.46075 1.45850 67.8 L6 10 21.951 5.63 1.43537 1.43385 95.2 L7 11 -23.017 0.10 12.435 1.43385 95.2 L8 13 -45.128 1.00 1.47642 1.47449 81.6 L9 14 22.048 4.58 1.43537 1.43385 95.2 L10 15 -50.557 0.10 16 50.014 1.00 1.46075 1.45850 67.8 L11 17 13.460 5.33 1.43537 1.43385 95.2 L12 18 -49.161 1.00 1.46075 1.45850 67.8013 16.88 1.43537 1.43385 95.2 L14 21 20.840 3.33 1.46075 1.45850 67.8 L15 22 14.890 2.39 23 -12.172 1.00 1.46075 1.45850 67.8 L16 24 -10.666 3.04 1.47642 1.47449 81.6 L17 25 -34.833 4.08 1.46075 1.45850 67.8 L18 26 -14.057 0.10 27 27.016 850 1.460 16 .307 82.00 (Values corresponding to conditional expressions) (1) f1 / fT = 10.097 (2) f2 / fT = 1.211 (3) | f3 | /fT=53.23 (4) | f4 | / fT = 3.601 (5) D3 / fT = 0.166 (6) N2n-N2p1 = 0.04105 (L8 and L9) (7) N2n-N2p2 = 0.04105 (L10 and L9) (8) ν2p1-ν2n = 13.6 (L8 and L9) (9) ν2p2-ν2n = 13.6 (L10 and L9) (10) ν2p1 = 95.2 (L8) (11) ν2p2 = 95.2 (L10)

FIG. 8 is a diagram showing various aberrations in the fourth embodiment. In each aberration diagram, NA is the numerical aperture, Y is the image height,
Solid line A represents visible light with a wavelength of 532.0 nm, and dotted line C represents C
Line (λ = 656.3 nm), and the dashed line F indicates the F line (λ = 656.3 nm).
486.1 nm), and the dashed line B indicates a near ultraviolet ray having a wavelength of 266.0 nm. In the astigmatism diagrams, S indicates a sagittal image plane, and T indicates a meridional image plane. As is clear from the aberration diagrams, in the fourth example, various aberrations are favorably corrected over a wide wavelength range from 266 nm to 656.3 nm, and excellent optical performance is secured. In Table (5) (values corresponding to the conditional expressions), the values of the conditional expressions (6) and (7) are not the refractive index for the d-line but the wavelength 532.
It is calculated based on the refractive index for visible light of nm. However, in the fourth embodiment, it goes without saying that the conditional expressions (6) and (7) are satisfied based on the refractive index for the d-line.

[Fifth Embodiment] FIG. 9 is a view showing a configuration of a microscope objective lens according to a fifth embodiment of the present invention. In the microscope objective lens of FIG. 9, the first lens group G1 includes:
It comprises, in order from the object side, a parallel plane plate L1, a cemented lens of a biconcave lens L2 and a biconvex lens L3, and a cemented lens of a biconcave lens L4 and a biconvex lens L5.

The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 and a biconvex lens L7 with the convex surface facing the object side, and a biconvex lens L8, a biconcave lens L9, and a biconvex lens L10. A triple cemented lens, a negative meniscus lens L11 and a biconvex lens L12 having a convex surface facing the object side, and a positive meniscus lens L having a concave surface facing the object side
13 and three cemented lenses. Further, the third lens group G3 includes, in order from the object side, a negative meniscus lens L14 having a convex surface facing the object side, a positive meniscus lens L15 having a convex surface facing the object side, and a negative meniscus lens L16 having a convex surface facing the object side. Of three cemented lenses. The fourth lens group G4 includes, in order from the object side, a triple cemented lens composed of a positive meniscus lens L17 having a concave surface facing the object side, a biconcave lens L18, and a negative meniscus lens L19 having a convex surface facing the object side. It comprises a negative meniscus lens L20 with the convex surface facing the side.

Table 6 below summarizes the data values of the fifth embodiment of the present invention. In Table (6), fT is wavelength 532
The focal length of the entire system (objective lens only) at infinity focusing on visible light of nm, NA is the numerical aperture on the object side, β is the magnification when the imaging lens is used, and WD is the working distance ( The axial distance between the object plane and the lens surface closest to the object side of the objective lens)
Respectively. Further, the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d
Is the distance between the lens surfaces, n532 is the refractive index for visible light having a wavelength of 532 nm, nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is the d line (λ = 587.6n).
m), respectively.

[0061]

Table 6 fT = 19.66 NA = 0.25 β = 10 × WD = 9.8 Surface number rd n532 nd v 1 ∞ 0.50 1.46075 1.45850 67.8 L1 2 ∞ 1.20 3 -30.158 1.32 1.46075 1.45850 67.8 L2 4 12.104 4.69 1.43537 1.43385 95.2 L3 5 -7.526 2.43 6 -7.217 1.91 1.46075 1.45850 67.8 L4 7 43.977 3.67 1.43537 1.43385 95.2 L5 8 -17.122 0.85 9 102.337 1.00 1.46075 1.45850 67.8 L6 10 27.259 3.66 1.43537 1.43385 95.2 L7 11 -39.105 0.10 841 1.43385 95.2 L8 13 -17.366 1.00 1.47642 1.47449 81.6 L9 14 31.908 3.87 1.43537 1.43385 95.2 L10 15 -34.338 0.10 16 49.899 1.00 1.46075 1.45850 67.8 L11 17 31.654 3.48 1.43537 1.43385 95.2 L12 18 -56.202 2.16 1.46075 1.45850 6.7.8 L19 20 1.00 1.46075 1.45850 67.8 L14 21 11.511 3.74 1.43537 1.43385 95.2 L15 22 47.536 1.00 1.46075 1.45850 67.8 L16 23 24.894 1.25 24 -955.978 2.99 1.46075 1.45850 67.8 L17 25 -16.306 1.00 1.43537 1.43385 95.2 L18 26 84.972 1.00 2.46075 1.272.9 67.8 .463 1.00 1.46075 1.45850 67.8 L20 29 13.760 80.00 (Values corresponding to the conditional expressions) (1) f1 / fT = 7.311 (2) f2 / fT = 1.156 (3) | f3 | /fT=110.104 (4) ) | F4 | / fT = 1.902 (5) D3 / fT = 0.064 (6) N2n-N2p1 = 0.04105 (L8 and L9) (7) N2n-N2p2 = 0.04105 (L10 and L9) (8) v2p1-v2n = 13.6 (L8 and L9) (9) v2p2-v2n = 13.6 (L10 and L9) (10) v2p1 = 95.2 (L8) (11) v2p2 = 95.2 ( L10)

FIG. 10 is a diagram showing various aberrations in the fifth embodiment. In each aberration diagram, NA is the numerical aperture, Y is the image height, solid line A is visible light having a wavelength of 532.0 nm, and dotted line C is
Represents the C line (λ = 656.3 nm), the dashed line F represents the F line (λ = 486.1 nm), and the dashed line B represents the wavelength 266.0 n.
m near ultraviolet rays. In the astigmatism diagrams, S indicates a sagittal image plane, and T indicates a meridional image plane. As is clear from the aberration diagrams, in the fifth embodiment, the wavelength ranges from 266 nm to 656.3.
Various aberrations are well corrected over a wide wavelength range of nm,
It can be seen that good optical performance is secured. In addition,
In (Values for Conditional Expressions) in Table (6), the values of Conditional Expressions (6) and (7) are not the refractive index for the d-line, but the wavelength 53.
It is calculated based on the refractive index for visible light of 2 nm. However, in the fifth embodiment, it goes without saying that the conditional expressions (6) and (7) are satisfied based on the refractive index for the d-line.

[Sixth Embodiment] FIG. 11 is a view showing a configuration of a microscope objective lens according to a sixth embodiment of the present invention.
In the microscope objective lens of FIG. 11, the first lens group G1
Are, in order from the object side, a parallel plane plate L1, a biconcave lens L2
A biconvex lens L3, a biconcave lens L4 and a biconvex lens L5, and a biconcave lens L6 and a biconvex lens L7.

The second lens group G2 is composed of, in order from the object side, a triplet lens composed of a biconvex lens L8, a biconcave lens L9, and a positive meniscus lens L10 having a convex surface facing the object side. Further, the third lens group G3 includes, in order from the object side, a negative meniscus lens L having a convex surface facing the object side.
It comprises a three-element cemented lens of a positive meniscus lens L12 having a convex surface facing the object side and a positive meniscus lens L13 having a convex surface facing the object side. The fourth lens group G4
Are, in order from the object side, a negative meniscus lens L14, a biconcave lens L15, and a biconvex lens L16 having a concave surface facing the object side.
It is composed of a cemented lens.

Table 7 below summarizes the data values of the sixth embodiment of the present invention. In Table (7), fT is wavelength 532
The focal length of the entire system (objective lens only) at infinity focusing on visible light of nm, NA is the numerical aperture on the object side, β is the magnification when the imaging lens is used, and WD is the working distance ( The axial distance between the object plane and the lens surface closest to the object side of the objective lens)
Respectively. Further, the surface number indicates the order of each lens surface from the object side, r indicates the radius of curvature of each lens surface, d
Is the distance between the lens surfaces, n532 is the refractive index for visible light having a wavelength of 532 nm, nd is the refractive index for visible light having a wavelength of 587.6 nm, and ν is the d line (λ = 587.6n).
m), respectively.

[0066]

[Table 7] fT = 10.04 NA = 0.25 β = 20 × WD = 8.8 Surface number rd n532 nd ν 1 ∞ 0.50 1.46075 1.45850 67.8 L1 2 ∞ 1.15 3 -55.555 1.00 1.46075 1.45850 67.8 L2 4 10.121 3.90 1.43537 1.43385 95.2 L3 5 -7.000 0.50 6 -73.994 1.00 1.46075 1.45850 67.8 L4 7 10.259 4.30 1.43537 1.43385 95.2 L5 8 -9.725 1.81 9 -6.604 1.00 1.46075 1.45850 67.8 L6 10 10.868 3.70 1.43537 1.43385 95.2 L7 11 -29.709 0.10 12 10.736 1.43537 1.43385 95.2 L8 13 -9.957 1.50 1.47652 1.47458 81.6 L9 14 19.660 2.23 1.43537 1.43385 95.2 L10 15 27.089 0.15 16 8.747 1.95 1.46075 1.45850 67.8 L11 17 5.000 5.00 1.43537 1.43385 95.2 L12 18 6.477 2.97 1.46075 1.45850 67.8 L13 1952.360 5.69 1.46075 1.45850 67.8 L14 21 -7.580 2.00 1.47652 1.47458 81.6 L15 22 11.024 2.41 1.46075 1.45850 67.8 L16 23 -13.525 80.00 (Values corresponding to conditional expressions) (1) f1 / fT = 2.475 (2) f2 / fT = 4.149 ( 3) | f3 | / fT = 0.059 (4) | f4 | /fT=1.68 (5) D3 / fT = 0.566 (6) N2n-N2p1 = 0.04105 (L8 and L9) (7) N2n-N2p2 = 0.04105 ( (8) ν2p1-ν2n = 13.6 (L8 and L9) (9) ν2p2-ν2n = 13.6 (L10 and L9) (10) ν2p1 = 95.2 (L8) (11) ν2p2 = 95.2 (L10)

FIG. 12 is a diagram showing various aberrations in the sixth embodiment. In each aberration diagram, NA is the numerical aperture, Y is the image height, solid line A is visible light having a wavelength of 532.0 nm, and dotted line C is
Represents the C line (λ = 656.3 nm), the dashed line F represents the F line (λ = 486.1 nm), and the dashed line B represents the wavelength 266.0 n.
m near ultraviolet rays. In the astigmatism diagrams, S indicates a sagittal image plane, and T indicates a meridional image plane. As is clear from the aberration diagrams, in the sixth embodiment, the wavelength is from 266 nm to 656.3.
Various aberrations are well corrected over a wide wavelength range of nm,
It can be seen that good optical performance is secured. In addition,
In (Values for Conditional Expressions) in Table (7), the values of Conditional Expressions (6) and (7) are not the refractive index for the d-line but the wavelength 53.
It is calculated based on the refractive index for visible light of 2 nm. However, in the sixth embodiment, it goes without saying that the conditional expressions (6) and (7) are satisfied based on the refractive index for the d-line.

As described above, in each of the above embodiments, by setting the parameters of each lens group so as to simultaneously satisfy the conditional expressions of the present invention, a wide wavelength range from the near ultraviolet region to the visible region can be obtained. Throughout, various aberrations such as spherical aberration, coma, and chromatic aberration are satisfactorily corrected simultaneously.

[0069]

As described above, according to the present invention,
Magnification is about 10-20 times and numerical aperture is 0.25-0.5.
With about 3, it is possible to realize a microscope objective lens in which various aberrations and chromatic aberrations are well corrected over a wide wavelength range from the visible light region to the near ultraviolet light region. That is, the microscope objective lens of the present invention is an optical system suitable for baking and fine processing of an IC pattern and high-resolution observation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a microscope objective lens according to a first example of the present invention.

FIG. 2 is a diagram illustrating various aberrations in the first example.

FIG. 3 is a diagram illustrating a configuration of a microscope objective lens according to a second example of the present invention.

FIG. 4 is a diagram illustrating various aberrations in the second example.

FIG. 5 is a diagram showing a configuration of a microscope objective lens according to a third example of the present invention.

FIG. 6 is a diagram illustrating various aberrations in the third example.

FIG. 7 is a diagram showing a configuration of a microscope objective lens according to Example 4 of the present invention.

FIG. 8 is a diagram illustrating various aberrations in the fourth example.

FIG. 9 is a diagram illustrating a configuration of a microscope objective lens according to a fifth example of the present invention.

FIG. 10 is a diagram illustrating various aberrations in the fifth example.

FIG. 11 is a diagram showing a configuration of a microscope objective lens according to Example 6 of the present invention.

FIG. 12 is a diagram illustrating various aberrations in the sixth example.

FIG. 13 is a diagram illustrating a configuration of an imaging lens in each embodiment.

FIG. 14 is a diagram illustrating a mechanism for automatically switching a parallel plane plate with respect to a microscope objective lens.

[Explanation of symbols]

 G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group L Each lens component 1 Microscope objective lens 2 Parallel plane plate 3 Rotating disk 4 Drive system 5 Half mirror 6 Light source 7, 9 Lens 8, 10 Detector

Claims (11)

[Claims] 1. A first lens group G having at least two cemented surfaces and having a positive refractive power as a whole in order from the object side.
1, a second lens group G2 having at least one bonding surface and having a positive refractive power as a whole, a third lens group G3 having at least one bonding surface, and a fourth lens having at least one bonding surface A microscope objective lens having a group G4, wherein a focal length of the first lens group G1 is f1,
When the focal length of the lens group G2 is f2 and the focal length of the entire microscope objective lens system is fT, the following condition is satisfied: 1 <f1 / fT <20 0.5 <f2 / fT <5. Microscope objective lens. 2. The focal length of the third lens group G3 is set to f3.
The microscope objective lens according to claim 1, wherein, when the focal length of the entire microscope objective lens system is fT, the following condition is satisfied: 1 <| f3 | / fT <150. 3. The focal length of the fourth lens group G4 is set to f4.
3. The microscope objective lens according to claim 1, wherein when a focal length of the entire microscope objective lens system is fT, a condition of 0.5 <| f4 | / fT <7 is satisfied. 4. 4. When the on-axis air gap between the third lens group G3 and the fourth lens group G4 is D3 and the focal length of the entire microscope objective lens system is fT, 0.05 <D3. The microscope objective lens according to any one of claims 1 to 3, wherein a condition of /fT<0.7 is satisfied. 5. The second lens group G2 includes a triplet lens formed by bonding one negative lens and two positive lenses, and the triplet lens in the second lens group G2. In the lens, when the refractive index of the one negative lens at a wavelength of 532 nm is N2n and the refractive indexes of the two positive lenses at a wavelength of 532 nm are N2p1 and N2p2, 0.04 <N2n-N2p1 0.04 < The microscope objective lens according to any one of claims 1 to 4, wherein a condition of N2n-N2p2 is satisfied. 6. In the three cemented lenses in the second lens group G2, the Abbe number of the one negative lens with respect to the d-line is ν2n, and the Abbe number of the two positive lenses with respect to the d-line is ν2p1. 6. The microscope objective lens according to claim 5, wherein the following condition is satisfied: 10 <ν2p1−ν2n 10 <ν2p2−ν2n 90 <ν2p1 90 <ν2p2. 7. The fourth lens group G4 has a three-element cemented lens formed by bonding one negative lens and two positive lenses, and the three-element cemented lens in the fourth lens group G4. In the lens, when the refractive index of the one negative lens at a wavelength of 532 nm is N4n and the refractive indexes of the two positive lenses at a wavelength of 532 nm are N4p1 and N4p2, 0.04 <N4n-N4p1 0.04 < The microscope objective lens according to any one of claims 1 to 6, wherein a condition of N4n-N4p2 is satisfied. 8. In the three cemented lenses in the fourth lens group G4, the Abbe number of the one negative lens with respect to the d line is ν4n, and the Abbe number of the two positive lenses with respect to the d line is ν4p1. 8. The microscope objective lens according to claim 7, wherein the following condition is satisfied: 10 <ν4p1−ν4n 10 <ν4p2−ν4n 90 <ν4p1 90 <ν4p2. 9. The microscope objective lens according to claim 1, wherein chromatic aberration is corrected for one wavelength in an ultraviolet wavelength range and three wavelengths in a visible wavelength range. The microscope objective lens according to the paragraph. 10. One of the wavelengths in the ultraviolet wavelength range is 26.
6 nm, and three wavelengths in the visible wavelength range are 48
The microscope objective according to claim 9, characterized in that it is 6.1 nm, 532 nm and 656.3 nm. 11. The microscope according to claim 1, wherein the optical material forming the microscope objective lens is any one of fluorite, synthetic quartz, and barium fluoride. Objective lens.