JP2010008527A - Liquid immersion microscope objective - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid immersion microscope objective which has a flat image surface and whose spherical aberration is satisfactorily corrected. <P>SOLUTION: The liquid immersion microscope objective OL has a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having two strong concave surfaces, which are arranged to be opposed, and having negative refractive power as a whole, wherein a lens arranged nearest to an image side in the third lens group G3 includes a meniscus single lens on whose object side one of the two strong concave surfaces is formed, and on whose image side a strong convex surface is formed. The objective OL is configured such that the Petzval sum of the two strong concave surfaces in the third lens group G3 satisfies a prescribed condition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an immersion microscope objective lens.

In many cases, an objective lens used in an immersion microscope has a flat surface closest to an object. This is because if this surface is made concave, bubbles or the like are likely to enter, which affects the observation of the object. In such an immersion microscope objective lens, for example, as shown in Patent Document 1, a lens arranged closest to the object side is a lens in which a plano-convex lens is embedded, and a meniscus lens joined to the plano-convex lens. The refractive index difference is increased to obtain a negative refractive power, and the image plane is corrected using a lens of a type including a strong concave surface disposed opposite to the third lens group.
JP-A-8-292373

  However, the immersion microscope objective lens configured as described above has a problem in that astigmatism cannot be corrected because the Petzval sum is not sufficiently small.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an immersion microscope objective lens having a flat image surface and a well-corrected spherical aberration.

In order to solve the above problems, an immersion microscope objective lens according to the present invention has a first lens group having a positive refractive power, a second lens group having a positive refractive power, and two strong concave surfaces. And a third lens group having these negative surfaces opposed to each other and having a negative refracting power as a whole, and the lens disposed closest to the image side of the third lens group has two surfaces on the object side. Is formed of a meniscus single lens in which one of the strong concave surfaces is formed and the strong convex surface is formed on the image side. Of the two strong concave surfaces, the radius of curvature of the concave surface arranged on the object side is r1, the refractive index for the d-line of the lens medium on which the concave surface is formed is N1, and the concave surface arranged on the image side is When the radius of curvature is r2, the refractive index with respect to the d-line of the lens medium on which the concave surface is formed is N2, and the focal length of the entire system is f, the following equation -0.8 <(1-N1) · f / r1 / N1 + (N2-1) .f / r2 / N2 <−0.4
It is configured to satisfy the following conditions.

In such an immersion microscope objective lens, the radius of curvature of the i-th surface counted from the object side among the lens surfaces constituting the first lens group is r _i, and the d-line of the medium on the image side of the surface the refractive index and N _i for, when the focal length of the whole system is f, the following equation _{Σ ((N i -N i-} 1) · f / (r i · N i · N i-1)) <0 .6
However, it is preferable that Σ satisfies the condition of indicating the sum of all lens surfaces constituting the first lens group.

  In such an immersion microscope objective lens, it is preferable that the lens disposed closest to the object side of the first lens group is a plano-convex single lens having a plane facing the object side.

  In such an immersion microscope objective lens, it is preferable that the second lens group has at least two sets of cemented lenses.

Further, in such an immersion microscope objective lens, when the minimum value of the Abbe numbers of the lens medium constituting the first lens group is νd _min , the following equation νd _min > 50
It is preferable to satisfy the following conditions.

Further, such an immersion microscope objective lens has the following formula νd _max <90, where νd _max is the maximum value among the Abbe numbers of the lens media constituting the entire system.
It is preferable to satisfy the following conditions.

  When the immersion microscope objective lens according to the present invention is configured as described above, it is possible to provide an immersion microscope objective lens having a flat image surface and a well-corrected spherical aberration.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the configuration of the immersion microscope objective lens according to the present embodiment will be described with reference to FIG. The immersion microscope objective lens OL 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, and a third lens group having a negative refractive power. G3.

  In such an immersion microscope objective lens OL, the first lens group G1 is a lens group for bringing a divergent light beam from an object close to a parallel light beam. The lens surface closest to the object side (the first surface in FIG. 1) of the first lens group G1 is the most when the tip of the immersion microscope objective lens OL is immersed in the immersion liquid and the object (specimen) is observed. In order to suppress the power of the first lens group G1 in this embodiment, it is preferably a flat surface or a concave surface having a gentle curvature so that bubbles or the like do not stay in the lens surface on the object side. ing. Further, in the first lens group G1, the lens disposed closest to the object side is configured as a single lens, so that the manufacturing cost can be reduced as compared with the case where the lens is configured as an embedded lens.

  The second lens group G2 is a lens group for receiving a substantially parallel light beam emitted from the first lens group G1 and converting it into a convergent light beam or a substantially parallel light beam and correcting spherical aberration and chromatic aberration. In particular, in order to sufficiently correct axial chromatic aberration, the second lens group G2 includes at least two sets of cemented lenses. In the example shown in FIG. 1, three sets of cemented lenses are provided.

  Furthermore, the third lens group G3 is a lens group that uses a convergent light beam or a substantially parallel light beam emitted from the second lens group G2 as a substantially parallel light beam. In order to correct the Petzval sum, the third lens group G3 includes a negative lens having a concave surface with a strong curvature on the image side (biconcave lens L10 in FIG. 1) and a negative lens having a concave surface with a strong curvature on the object side. (Negative meniscus lens L11 in FIG. 1), and these concave surfaces (the 16th surface and the 17th surface in FIG. 1) are arranged to face each other. At this time, among the lenses constituting the third lens group G3, the lens disposed closest to the image side is a meniscus having a concave surface on the object side (a concave surface disposed on the image side among the above-described opposing concave surfaces). It is configured as a single lens.

  Now, conditions for configuring the immersion microscope objective lens OL according to the present embodiment will be described below. First, in the third lens group G3, among the opposing strong concave surfaces described above, the radius of curvature of the concave surface (the 16th surface in FIG. 1) arranged on the object side is r1, and the lens (FIG. 1 in FIG. 1) is formed. The refractive index with respect to the d-line of the biconcave lens L10) is N1, the radius of curvature of the concave surface (the 17th surface in FIG. 1) arranged on the image side is r2, and the lens on which the concave surface is formed (the negative meniscus lens in FIG. 1) When the refractive index with respect to the d-line of L11) is N2, and the focal length of the entire system of the immersion microscope objective lens OL is f, the following conditional expression (1) is satisfied.

-0.8 <(1-N1) .f / r1 / N1 + (N2-1) .f / r2 / N2 <-0.4
(1)

  Conditional expression (1) is a condition for defining the range of Petzval sum of strong concave surfaces facing each other in the third lens group G3. Exceeding the upper limit of conditional expression (1) is not preferable because the Petzval sum cannot be corrected sufficiently and astigmatism increases. On the other hand, if the value is below the lower limit value, the curvature of the strong concave surfaces facing each other becomes too strong, so that the coma becomes large at a high image height, which is not preferable.

Moreover, the immersion microscope objective lens OL, of the lens surfaces constituting the first lens group G1, the radius of curvature of the i-th surface and r _i counted from the object side, the image side of the medium of the surface the refractive index at the d-line and N _i, and a focal length of the whole system is f, it is desirable to satisfy the following condition (2).

Σ ((N _i −N _i−1 ) · f / (r _i · N _i · N _i−1 )) <0.6 (2)
However, Σ indicates the sum of all lens surfaces constituting the first lens group.

  Conditional expression (2) is a condition for defining the range of Petzval sum of the first lens group G1. Exceeding the upper limit of conditional expression (2) is not preferable because the Petzval sum generated in the first lens group G1 becomes large and cannot be corrected by the third lens group G3. In addition, the lateral chromatic aberration is increased, which makes correction difficult and is not preferable.

Further, it is desirable that the following conditional expression (3) is satisfied when the minimum value of the Abbe numbers of the lenses constituting the first lens group G1 is νd _min .

νd _min > 50 (3)

  Conditional expression (3) defines the Abbe number of the glass material of the lens constituting the first lens group G1, and if a lens made of a glass material that falls below the lower limit value of this conditional expression (3) is used, chromatic aberration of magnification is generated. Becomes large and correction becomes difficult.

Furthermore, it is preferable that the following conditional expression (4) is satisfied when the maximum value of the Abbe numbers of the lenses constituting the entire immersion microscope objective lens OL system is νd _max .

νd _max <90 (4)

  Conditional expression (4) defines the Abbe number of the glass material of the lens constituting the immersion microscope objective lens OL, and a glass material exceeding the upper limit of this conditional expression (4) has a lower refractive index and curvature. The radius becomes tight and higher-order spherical aberration and coma increase, which makes correction difficult.

  Hereinafter, three examples of the immersion microscope objective lens OL according to the present embodiment will be described. Here, the immersion microscope objective lens OL is of the infinity correction type, has the configuration shown in FIG. 7, and is used together with the imaging lens IL having the specifications shown in Table 1. In Table 1, the first column m is the number of each optical surface from the object side, the second column r is the radius of curvature of each optical surface, and the third column d is from each optical surface to the next optical surface. , The fourth column nd indicates the refractive index with respect to the d-line, and the fifth column νd indicates the Abbe number. Here, the refractive index of air of 1.0000 is omitted. The description of the specification table is the same in the following embodiments.

(Table 1)
m r d nd νd
1 75.043 5.1 1.62280 57.0
2 -75.043 2.0 1.74950 35.2
3 1600.580 7.5
4 50.256 5.1 1.66755 42.0
5 -84.541 1.8 1.61266 44.4
6 36.911

  The imaging lens IL includes a cemented lens in which a biconvex lens L21 and a biconcave lens L22 are cemented in order from the object side, and a cemented lens in which a biconvex lens L23 and a biconcave lens L24 are cemented.

[First embodiment]
FIG. 1 shows an immersion microscope objective lens OL1 according to the first embodiment. The immersion microscope objective lens OL1 is used in a microscope in which a specimen (object) is placed under a cover plate (not shown in FIG. 1) and the tip is immersed in the immersion liquid. A first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. It is configured. The first lens group G1 includes a plano-convex lens L1 having a flat object side and a positive meniscus lens L2 having a concave surface facing the object side. The second lens group G2 includes a cemented lens in which a negative meniscus lens L3 having a convex surface facing the object side and a biconvex lens L4 are cemented, and a negative meniscus lens L5 having a convex surface in the object side and a biconvex lens L6. The lens includes a cemented lens and a cemented lens in which a negative meniscus lens L7 having a convex surface facing the object side and a biconvex lens L8 are cemented. Furthermore, the third lens group G3 includes a cemented lens obtained by cementing a biconvex lens L9 and a biconcave lens L10 having a strong concave surface on the image side, and a negative meniscus lens L11 having a strong concave surface directed toward the object side.

  Table 2 shows specifications of the immersion microscope objective lens OL1 according to the first example shown in FIG. In Table 2, f represents the focal length of the entire system of the immersion microscope objective lens OL1, β represents the magnification, NA represents the numerical aperture, and WD represents the working distance. D0 represents the distance on the optical axis from the sample to the apex of the lens surface closest to the object side of the first lens closest to the object side (lens L1) excluding the thickness of the cover plate. Further, the numbers of the optical surfaces shown in the first column m correspond to the surface numbers 1 to 18 shown in FIG. In the second column r, the curvature radius 0.0000 indicates a plane. Further, Table 2 also shows values corresponding to the conditional expressions (1) to (4), that is, condition corresponding values. Here, the cover plate used in this example has a thickness of 0.17 mm, a refractive index of 1.522 for the d-line and an Abbe number of 58.8, and the immersion liquid has a refractive index of 1.515 for the d-line, The Abbe number is 41.4. These descriptions are the same in the following embodiments.

  Unless otherwise specified, “mm” is generally used as the unit of the radius of curvature r, the surface interval d, the focal length f of the entire system, and other lengths that are listed in all the following specifications. Since the same optical performance can be obtained even when proportional expansion or reduction is performed, the unit is not limited to “mm”, and other appropriate units may be used.

(Table 2)
f = 2
β = 100x
NA = 1.25
WD = 0.2
d0 = 0.22

m r d nd νd
1 0.000 2.55 1.518 59.0
2 -1.983 0.20
3 -12.430 3.85 1.498 82.6
4 -5.316 2.40
5 91.019 1.00 1.516 64.1
6 10.978 6.00 1.498 82.6
7 -13.364 0.99
8 51.173 1.00 1.613 44.5
9 10.399 5.70 1.498 82.6
10 -18.881 1.00
11 37.130 1.00 1.835 42.7
12 9.000 4.80 1.498 82.6
13 -50.703 10.12
14 6.818 6.00 1.498 82.6
15 -12.337 7.00 1.640 60.1
16 2.289 2.00
17 -2.692 8.00 1.804 39.6
18 -6.889

(1) (1-N1) .f / r1 / N1 + (N2-1) .f / r2 / N2 = -0.672
(2) Σ ((N _i −N _i−1 ) · f / (r _i · N _i · N _i−1 )) = 0.416
(3) νd _min = 59.0
(4) νd _max = 82.6

Of the condition corresponding values shown in Table 2, νd _min in the conditional expression (3) is the Abbe number of the plano-convex lens L1, and νd _max in the conditional expression (4) is the Abbe number of the positive meniscus lens L2, etc. . Thus, it can be seen that all the conditional expressions (1) to (4) are satisfied in the first embodiment. FIG. 2 is a diagram showing various aberrations of spherical aberration, astigmatism, lateral chromatic aberration, and distortion for the d-line, C-line, F-line, and g-line rays of the immersion microscope objective lens OL1 according to the first embodiment. Indicates. Among these aberration diagrams, the spherical aberration diagram shows the aberration amount with respect to the numerical aperture NA, and the astigmatism diagram, the lateral chromatic aberration diagram, and the distortion diagram show the aberration amount with respect to the image height Y. In the spherical aberration diagram and the magnification chromatic aberration diagram, the solid line indicates the d line, the dotted line indicates the C line, the alternate long and short dash line indicates the F line, and the alternate long and two short dashes line indicates the g line. Further, in the astigmatism diagram, the solid line indicates the meridional image plane for each wavelength, and the broken line indicates the sagittal image plane for each wavelength. The explanation of these aberration diagrams is the same in the following examples. As is apparent from the respective aberration diagrams shown in FIG. 2, it can be seen that in the first embodiment, various aberrations are satisfactorily corrected and excellent imaging performance is ensured.

[Second Embodiment]
Next, an immersion microscope objective lens OL2 shown in FIG. 3 will be described as a second embodiment. In the immersion microscope objective lens OL2 shown in FIG. 3, the specimen (object) is placed under the cover plate (not shown in FIG. 3), and the specimen is observed with the tip immersed in the immersion liquid. Objective lens used in a microscope, and 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, and a third lens having a negative refractive power It has a lens group G3. The first lens group G1 includes a plano-convex lens L1 having a flat object side and a positive meniscus lens L2 having a concave surface facing the object side. The second lens group G2 includes a cemented lens in which a negative meniscus lens L3 having a convex surface facing the object side and a biconvex lens L4 are cemented, and a negative meniscus lens L5 having a convex surface in the object side and a biconvex lens L6. The lens includes a cemented lens and a cemented lens in which a negative meniscus lens L7 having a convex surface facing the object side and a biconvex lens L8 are cemented. Furthermore, the third lens group G3 includes a cemented lens obtained by cementing a biconvex lens L8 and a biconcave lens L10 having a strong concave surface on the image side, and a negative meniscus lens L11 having a strong concave surface directed toward the object side.

  Table 3 shows the specifications of the immersion microscope objective lens OL2 shown in FIG. In addition, the surface number shown in Table 3 corresponds with the surface numbers 1-18 shown in FIG.

(Table 3)
f = 2
β = 100x
NA = 1.25
WD = 0.2
d0 = 0.22

m r d nd νd
1 0.000 2.55 1.518 59.0
2 -1.983 0.20
3 -11.368 3.85 1.487 84.5
4 -5.421 2.40
5 85.304 1.00 1.517 64.2
6 12.767 6.90 1.487 84.5
7 -12.767 0.40
8 42.448 1.00 1.613 44.5
9 10.579 6.30 1.487 84.5
10 -19.726 1.00
11 29.923 1.00 1.835 43.0
12 9.141 4.80 1.487 84.5
13 -90.622 10.10
14 6.781 6.00 1.487 84.5
15 -12.301 7.00 1.640 60.2
16 2.380 2.00
17 -2.670 8.00 1.805 39.6
18 -6.967

(1) (1-N1) .f / r1 / N1 + (N2-1) .f / r2 / N2 = -0.662
(2) Σ ((N _i −N _i−1 ) · f / (r _i · N _i · N _i−1 )) = 0.407
(3) νd _min = 59.0
(4) νd _max = 84.5

Of the condition corresponding values shown in Table 3, νd _min in the conditional expression (3) is the Abbe number of the planoconvex lens L1, and νd _max in the conditional expression (4) is the Abbe number of the positive meniscus lens L2, etc. . Thus, it can be seen that all the conditional expressions (1) to (4) are satisfied in the second embodiment. FIG. 4 shows various aberration diagrams of spherical aberration, astigmatism, lateral chromatic aberration, and distortion of the immersion microscope objective lens OL2 according to the second example. As is apparent from the respective aberration diagrams shown in FIG. 4, it is understood that various aberrations are satisfactorily corrected and excellent imaging performance is secured in the second embodiment.

[Third embodiment]
Finally, an immersion microscope objective lens OL3 shown in FIG. 5 will be described as a third embodiment. The immersion microscope objective lens OL3 shown in FIG. 5 also has a specimen (object) placed under the cover plate (not shown in FIG. 5), and the specimen is observed with the tip immersed in the immersion liquid. Objective lens used in a microscope, and 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, and a third lens having a negative refractive power It has a lens group G3. The first lens group G1 includes a plano-convex lens L1 having a flat object side and a positive meniscus lens L2 having a concave surface facing the object side. The second lens group G2 includes a cemented lens in which a negative meniscus lens L3 having a convex surface facing the object side and a biconvex lens L4 are cemented, and a negative meniscus lens L5 having a convex surface in the object side and a biconvex lens L6. The lens includes a cemented lens and a cemented lens in which a negative meniscus lens L7 having a convex surface facing the object side and a biconvex lens L8 are cemented. Furthermore, the third lens group G3 includes a cemented lens obtained by cementing a biconvex lens L8 and a biconcave lens L10 having a strong concave surface on the image side, and a negative meniscus lens L11 having a strong concave surface directed toward the object side.

  Table 4 shows the specifications of the immersion microscope objective lens OL3 shown in FIG. In addition, the surface number shown in Table 4 corresponds with the surface numbers 1-18 shown in FIG.

(Table 4)
f = 2
β = 100x
NA = 1.25
WD = 0.2
d0 = 0.22

m r d nd νd
1 0.000 2.55 1.518 59.0
2 -1.983 0.30
3 -20.775 5.00 1.498 82.6
4 -6.214 3.00
5 60.617 1.00 1.613 44.5
6 13.300 6.00 1.498 82.6
7 -13.300 0.50
8 35.613 1.00 1.640 60.1
9 11.408 6.00 1.498 82.6
10 -27.117 0.40
11 47.100 1.00 1.835 42.7
12 9.347 5.50 1.498 82.6
13 -49.863 4.50
14 7.625 6.00 1.498 82.6
15 -19.900 9.20 1.640 60.1
16 3.500 2.10
17 -2.399 10.20 1.805 25.4
18 -8.807

(1) (1-N1) .f / r1 / N1 + (N2-1) .f / r2 / N2 = -0.595
(2) Σ ((N _i −N _i−1 ) · f / (r _i · N _i · N _i−1 )) = 0.419
(3) νd _min = 59.0
(4) νd _max = 82.6

Of the condition corresponding values shown in Table 4, νd _min in the conditional expression (3) is the Abbe number of the planoconvex lens L1, and νd _max in the conditional expression (4) is the Abbe number of the positive meniscus lens L2, etc. . Thus, it can be seen that all the conditional expressions (1) to (4) are satisfied in the third embodiment. FIG. 6 shows various aberration diagrams of the spherical aberration, astigmatism, lateral chromatic aberration, and distortion of the immersion microscope objective lens OL3 according to the third example. As is apparent from the respective aberration diagrams shown in FIG. 6, it is understood that various aberrations are satisfactorily corrected and excellent imaging performance is secured in the third embodiment.

  The immersion microscope objective lenses OL1 to OL3 shown in the above three embodiments are summarized as follows. First, these immersion microscope objective lenses OL1 to OL3 are embedded in the most object side lens of the first lens group G1 because the opposing strong concave surface in the third lens group G3 satisfies the conditional expression (1). It can be seen that correction of coma aberration and flatness of the image plane are ensured without using a lens. Further, since the Petzval sum of the first lens group G1 is small and satisfies the conditional expression (2), not only flatness of the image plane but also correction of chromatic aberration is performed. Further, in the immersion microscope objective lens OL1 shown in these examples, the lens arranged closest to the object side of the first lens group G1 is composed of a plano-convex lens (single lens), and thus is manufactured as compared with an embedded lens. There is an advantage that the cost is low.

  In addition, as shown in the present embodiment, when a lens of a type including a strong concave surface disposed opposite to the third lens group G3 is provided, normally, a cemented lens composed of two negative and positive lenses is provided on the image side. Although it is necessary to correct the lateral chromatic aberration by providing a lens, since the Abbe number of the lenses constituting the first lens group G1 satisfies the conditional expression (3), the magnification generated in the first lens group G1 Chromatic aberration is suppressed to a minimum, and a plurality of cemented lenses are provided in the second lens group G2, and the axial chromatic aberration is corrected and balanced with the chromatic aberration of magnification, whereby the most lens side of the third lens group G3. This lens can be handled with a single lens, which can lead to cost reduction. Further, since the Abbe numbers of all the lenses constituting the immersion microscope objective lenses OL1 to OL3 satisfy the conditional expression (4), high-order spherical aberration and coma aberration can be suppressed, and expensive glass can be used. It can be used without using it, leading to cost reduction.

  Of course, it is possible to further flatten the image plane by using the lens closest to the object side of the first lens group G1 as an embedded lens, and to improve chromatic aberration by using a lens having an Abbe number of 90 or more. Is also possible.

It is a lens block diagram which shows the structure of the immersion microscope objective lens which concerns on 1st Example. FIG. 6 is a diagram illustrating all aberrations of the immersion microscope objective lens according to the first example. It is a lens block diagram which shows the structure of the immersion microscope objective lens which concerns on 2nd Example. FIG. 6 is a diagram illustrating various aberrations of the immersion microscope objective lens according to the second example. It is a lens block diagram which shows the structure of the immersion microscope objective lens which concerns on 3rd Example. FIG. 9 is a diagram illustrating all aberrations of the immersion microscope objective lens according to the third example. It is a lens block diagram of the imaging lens used with the said immersion microscope objective lens.

Explanation of symbols

OL (OL1 to OL3) immersion microscope objective lens G1 first lens group G2 second lens group G3 third lens group

Claims (6)

From the object side,
A first lens group having a positive refractive power;
A second lens group having a positive refractive power;
A third lens group having two strong concave surfaces, the concave surfaces being opposed to each other, and having negative refractive power as a whole;
The lens disposed closest to the image side of the third lens group is constituted by a meniscus single lens in which one of the two strong concave surfaces is formed on the object side and a strong convex surface is formed on the image side,
Of the two strong concave surfaces, the radius of curvature of the concave surface arranged on the object side is r1, the refractive index for the d-line of the lens medium on which the concave surface is formed is N1, and the curvature of the concave surface arranged on the image side. When the radius is r2, the refractive index with respect to the d-line of the lens medium on which the concave surface is formed is N2, and the focal length of the entire system is f, the following equation −0.8 <(1-N1) · f / r1 /N1+(N2-1).f/r2/N2<−0.4
Immersion microscope objective lens that satisfies the above conditions. Of the lens surfaces constituting the first lens group, the radius of curvature of the i-th surface counted from the object side is r _i , the refractive index for the d-line of the medium on the image side of the surface is N _i , When the focal length of the system is f, the following formula Σ ((N _i −N _i−1 ) · f / (r _i · N _i · N _i−1 )) <0.6
However, the immersion microscope objective lens according to claim 1, wherein Σ satisfies a condition that indicates a sum of all lens surfaces constituting the first lens group.   3. The immersion microscope objective lens according to claim 1, wherein the lens disposed closest to the object side of the first lens group is a plano-convex single lens having a plane facing the object side.   The immersion microscope objective lens according to claim 1, wherein the second lens group includes at least two sets of cemented lenses. Of Abbe number of the lens medium constituting the first lens group, when the minimum value was [nu] d _min, the following equation [nu] d _min> 50
The immersion microscope objective lens according to any one of claims 1 to 4, which satisfies the following condition. Of the Abbe numbers of the lens media constituting the entire system, when the maximum value is νd _max , the following equation νd _max <90
The immersion microscope objective lens according to claim 1, which satisfies the following condition.

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