JP2017097201A - Microscopy optical system and microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that inexpensively achieves an excellent aberration performance even when an interval between an objective lens and an image formation lens is large.SOLUTION: A microscope optical system 11 comprises, in order from an object,: an infinity correction type objective lens 1; and an image formation lens 10. The image formation lens 10 is composed of, in order from the object side,: a first lens group G21 that having positive refractive power; and a second lens group G22 that serves as a cemented lens composed of a positive lens and a negative lens. The microscope optical system 11 satisfies following conditions 0.3≤D/F≤0.7 (1), and 5≤|F/F| (2) when D is a distance from a barrel abutting surface of the objective lens 1 to a lens surface present on a most object side of the image formation lens 10, F is a focal length of the image formation lens 10, and Fis a focal length of the second lens group G22.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a microscope optical system and a microscope technique.

  A microscope optical system is required to have a configuration capable of efficiently manufacturing at a low cost, together with the ability to correct aberrations satisfactorily. In order to manufacture a microscope optical system at a relatively low cost, it is effective to reduce the number of lenses constituting the objective lens.

  However, it is difficult to obtain good aberration performance with a single objective lens having a small number of lenses. For this reason, a microscope optical system that employs a compensation-type design philosophy that corrects chromatic aberration satisfactorily in the entire microscope optical system by intentionally generating chromatic aberration equivalent to the chromatic aberration generated in the objective lens. Has been proposed. Such a microscope optical system is disclosed in Patent Document 1 and Patent Document 2, for example.

JP 2012-118340 A JP 2011-175238 A

  By the way, the microscope optical system is designed so that the aberration performance changes depending on the distance between the objective lens and the imaging lens, and the best performance is exhibited when the objective lens and the imaging lens are arranged at a predetermined interval. As the distance between the objective lens and the imaging lens is larger, it becomes more difficult to correct the lateral chromatic aberration. Therefore, in the design of the microscope optical system, the predetermined distance is usually not designed so large.

  In view of the above circumstances, an object of the present invention is to provide a microscope optical system and a microscope that can realize good aberration performance at low cost even when the distance between the objective lens and the imaging lens is large.

One embodiment of the present invention provides a microscope optical system including an infinity-correction objective lens and an imaging lens. The imaging lens includes, in order from the object side, a first lens group having a positive refractive power and a second lens group that is a cemented lens including a positive lens and a negative lens. In the microscope optical system, D is a distance from the lens surface of the objective lens to the lens surface closest to the object side of the imaging lens, F is a focal length of the imaging lens, and F _G2 is the second distance. When the focal length of the lens group is satisfied, the following conditional expression is satisfied.
0.3 ≦ D / F ≦ 0.7 (1)
5 ≦ | F _G2 / F | (2)

  Another aspect of the present invention provides a microscope including the above-described microscope optical system.

  ADVANTAGE OF THE INVENTION According to this invention, even if the space | interval of an objective lens and an imaging lens is large, the microscope optical system and microscope which implement | achieve favorable aberration performance cheaply can be provided.

It is the figure which showed the structure of the microscope 100 which concerns on one Embodiment of this invention. It is sectional drawing of the objective lens 1 of 10 times. It is sectional drawing of the objective lens 2 of 40 times. 1 is a cross-sectional view of an imaging lens 10 according to Example 1. FIG. 1 is a cross-sectional view of a microscope optical system 11 including an objective lens 1 and an imaging lens 10. FIG. 2 is a cross-sectional view of a microscope optical system 12 including an objective lens 2 and an imaging lens 10. FIG. FIG. 6 is an aberration diagram of the microscope optical system 11. FIG. 6 is an aberration diagram of the microscope optical system 12. 6 is a cross-sectional view of an imaging lens 20 according to Example 2. FIG. 2 is a cross-sectional view of a microscope optical system 21 including an objective lens 1 and an imaging lens 20. FIG. 2 is a sectional view of a microscope optical system 22 including an objective lens 2 and an imaging lens 20. FIG. FIG. 6 is an aberration diagram of the microscope optical system 21. FIG. 6 is an aberration diagram of the microscope optical system 22. 6 is a cross-sectional view of an imaging lens 30 according to Example 3. FIG. 2 is a cross-sectional view of a microscope optical system 31 including an objective lens 1 and an imaging lens 30. FIG. 2 is a cross-sectional view of a microscope optical system 32 including an objective lens 2 and an imaging lens 30. FIG. FIG. 6 is an aberration diagram of the microscope optical system 31. FIG. 6 is an aberration diagram of the microscope optical system 32. 6 is a cross-sectional view of an imaging lens 40 according to Example 4. FIG. 2 is a sectional view of a microscope optical system 41 including an objective lens 1 and an imaging lens 40. FIG. 2 is a cross-sectional view of a microscope optical system 42 including an objective lens 2 and an imaging lens 40. FIG. FIG. 6 is an aberration diagram of the microscope optical system 41. FIG. 6 is an aberration diagram of the microscope optical system 42. 6 is a cross-sectional view of an imaging lens 50 according to Example 5. FIG. 2 is a sectional view of a microscope optical system 51 including an objective lens 1 and an imaging lens 50. FIG. 2 is a cross-sectional view of a microscope optical system 52 including an objective lens 2 and an imaging lens 50. FIG. FIG. 6 is an aberration diagram of the microscope optical system 51. FIG. 6 is an aberration diagram of the microscope optical system 52. 10 is a cross-sectional view of an imaging lens 60 according to Example 6. FIG. 2 is a sectional view of a microscope optical system 61 including an objective lens 1 and an imaging lens 60. FIG. 2 is a cross-sectional view of a microscope optical system 62 including an objective lens 2 and an imaging lens 60. FIG. FIG. 6 is an aberration diagram of the microscope optical system 61. FIG. 6 is an aberration diagram of the microscope optical system 62.

  FIG. 1 is a diagram showing a configuration of a microscope 100 according to an embodiment of the present invention. The microscope 100 is an upright microscope including a compensation-type microscope optical system including an infinity-corrected objective lens (10-times objective lens 1, 40-times objective lens 2) and an imaging lens 3. The objective lens 1 and the objective lens 2 having different magnifications are attached to the revolver 9 and are selectively arranged on the optical path by the rotation of the revolver 9. The microscope 100 further includes an eyepiece 4 for visually observing an observation object placed on the stage 8, a camera 5 for imaging the observation object, and a light source 6 for epi-illumination for illuminating the observation object. And a light source 7 for transmitted illumination.

  FIG. 2 is a cross-sectional view of the 10 × objective lens 1. The objective lens 1 includes, in order from the object side, a first lens group G1 having a positive refractive power composed of one lens component (lens L1) having a convex surface facing the image side, and a meniscus lens component having a concave surface facing the object side. It includes a second lens group G2 having a negative refractive power composed of (junction lens CL1) and a third lens group G3 having a positive refractive power. The lens component of the first lens group G1 is composed of one meniscus lens (lens L1) having a concave surface facing the object side. The meniscus lens component of the second lens group G2 is a cemented lens CL1 composed of a lens L2 and a lens L3, and the lens L2 and the lens L3 are each configured as a meniscus lens. The lens component of the third lens group G3 is a cemented lens CL2 including a lens L4 that is a biconcave lens and a lens L5 that is a biconvex lens.

  In the present specification, the “lens component” means that only two surfaces, the object side surface and the image side surface, of the lens surface through which the light beam passes are air (or immersion liquid), regardless of whether they are a single lens or a cemented lens. ) Is a block of lens blocks in contact with.

The focal length F _ob , magnification β, object-side numerical aperture NA _ob , and exit pupil diameter PR of the objective lens 1 are as follows.
F _ob = 22.5mm, β = 10, NA _ob = 0.25, PR = 5.8057mm

The lens data of the objective lens 1 is as follows. Note that INFINITY in the lens data indicates infinity (∞).
Objective lens 1
srd nd νd
0 (object surface) INFINITY 0.1700 1.52100 56.02
1 INFINITY 8.2786
2 -28.3039 1.5307 1.72916 54.68
3 -6.4891 2.4971
4 -4.4792 4.0559 1.69895 30.13
5 -29.3512 5.5200 1.76200 40.10
6 -9.8266 4.9279
7 -82.0138 5.0000 1.74951 35.33
8 17.4594 2.6510 1.61800 63.33
9 -24.2343 10.4288
10 (Body surface) INFINITY D

  Here, s is a surface number, r is a radius of curvature (mm), d is a surface interval (mm), nd is a refractive index with respect to the d-line, and νd is an Abbe number. The surfaces indicated by the surface numbers s0 and s1 indicate the object-side surface (object surface) and the image-side surface of the cover glass CG, respectively. The surfaces indicated by the surface numbers s2 and s9 are the first surface and the final surface of the objective lens 1, respectively. Reference numeral s10 denotes a body-mounted surface of the objective lens 1. The body-mounted surface is a surface that contacts the revolver when the objective lens is attached to the revolver, and is a surface that serves as a reference for the same focal length. The surface distance d10 indicates a distance D from the body surface to the lens surface (first surface) closest to the object side of the imaging lens.

  FIG. 3 is a cross-sectional view of the 40 × objective lens 2. The objective lens 2 includes, in order from the object side, a first lens group G1 having a positive refractive power composed of a meniscus lens component (lens L1) having a concave surface directed toward the object side, and a cemented lens component CL1 (lens L2, lens L3). A second lens group G2 having a positive refractive power, and a meniscus lens having a concave surface facing the image side, the cemented lens component CL2 (lens L4, L5) and the cemented lens component CL3 (lens L6, L7). And a third lens group G3 including a component (lens L8). Each cemented lens component included in the second lens group G2 includes a negative lens and a positive lens from the object side, and has a relatively weak positive refractive power.

The focal length F _ob of the objective lens 2, the magnification β, the numerical aperture NA _ob on the object side, and the exit pupil diameter PR are as follows.
F _ob = 5.6mm, β = 40, NA _ob = 0.65, PR = 4.7815mm

The lens data of the objective lens 2 is as follows. Note that INFINITY in the lens data indicates infinity (∞).
Objective lens 2
srd nd νd
0 (object surface) INFINITY 0.1700 1.52100 56.02
1 INFINITY 0.8047
2 -4.1708 4.0868 1.77250 49.60
3 -3.5948 0.2268
4 -183.5696 1.0488 1.61340 44.27
5 22.4457 1.8003 1.49700 81.54
6 -20.7144 0.9322
7 -73.7234 1.1000 1.75520 27.51
8 17.4536 6.3976 1.49700 81.54
9 -11.0237 0.7387
10 82.8076 1.2000 1.65412 39.68
11 13.1004 4.1929 1.43875 94.93
12 -15.6053 24.4665
13 9.4818 4.2624 1.80518 25.42
14 7.2405 -6.3678
15 (Body surface) INFINITY D

  The surfaces indicated by the surface numbers s2 and s14 are the first surface and the final surface of the objective lens 2, respectively. Reference numeral s15 denotes a body-mounted surface of the objective lens 2. The surface distance d15 indicates the distance D from the body surface to the lens surface (first surface) closest to the object side of the imaging lens.

  The imaging lens 3 is an imaging lens for a microscope that is used in combination with the objective lens 1 or the objective lens 2. The imaging lens 3 has a three-lens two-group configuration, and includes, in order from the object side, a first lens group having a positive refractive power and a second lens group that is a cemented lens including a positive lens and a negative lens. The first lens group is composed of a single lens.

  In general, when the distance between the objective lens and the imaging lens is increased, off-axis rays enter the imaging lens at a higher beam height, and the incident angle of the imaging lens to the lens surface also increases. Thereby, a difference (refractive angle difference) between the refraction angle of the short wavelength light and the refraction angle of the long wavelength light occurs, and the microscope optical system has a different focal length for each wavelength. As a result, light is condensed at different positions for each wavelength, and lateral chromatic aberration occurs. In order to correct this lateral chromatic aberration, it is necessary to make the focal length for each wavelength uniform. For convex lenses (positive lenses), the focal length for short-wavelength light is made relatively shorter than the focal length for long-wavelength light, and the focal length for long-wavelength light is short-wavelength light. There is an effect of relatively increasing with respect to the focal length. The opposite is true for concave lenses (negative lenses).

  In the microscope optical system according to the present embodiment, the imaging lens 3 has a second lens group that is a cemented lens including a positive lens and a negative lens. By appropriately designing the focal length of the second lens group, the second lens group becomes the first lens group of the imaging lens 3 (more precisely, the objective lens and the first lens group of the imaging lens 3). Therefore, the variation in the focal length for each wavelength is suppressed. Therefore, according to the microscope optical system according to the present embodiment, the focal length of the second lens group is appropriately designed, so that the entire microscope optical system can be configured even when the distance between the objective lens and the imaging lens is larger than the conventional one. Thus, good aberration performance can be realized.

More specifically, the microscope optical system is configured to satisfy the following conditional expressions (1) and (2) in order to achieve good aberration performance. Here, D is the distance from the cylinder with surface of the objective lens to the lens surface the most object side of the imaging lens 3, F is the focal length of the imaging lens 3, F _G2 of the imaging lens 3 This is the focal length of the second lens group. The body-mounted surface is a surface of the objective lens that is in contact with the revolver 9, and is a surface that serves as a reference for the same focal length.
0.3 ≦ D / F ≦ 0.7 (1)
5 ≦ | F _G2 / F | (2)

  Conditional expression (1) is an expression that defines the distance between the objective lens used for observation and the imaging lens 3 in relation to the focal length of the imaging lens 3. When the D / F exceeds the upper limit value, the entrance pupil position (exit pupil position of the objective lens) is too far from the first lens group of the imaging lens 3. For this reason, the off-axis ray height when entering the first lens group becomes extremely high, and not only the lateral chromatic aberration but also the spherical aberration, the off-axis ray coma and astigmatism become large. Furthermore, since the outer diameter of the imaging lens 3 is increased, manufacturability is also reduced. On the other hand, if the D / F falls below the lower limit value, the entrance pupil position becomes too close to the first lens group of the imaging lens 3. For this reason, the off-axis ray height when entering the first lens group is not sufficiently high, and it is difficult to satisfactorily correct the coma and astigmatism of the off-axis ray. Further, assuming that the eyepiece lens is at a predetermined height, the distance between the objective lens and the imaging lens 3 is too small, so that the position of the stage 8 on which the observation target is placed becomes high, and the operability of the microscope 100 is improved. descend.

Conditional expression (2) is an expression that defines the ratio between the focal length of the second lens group and the focal length of the imaging lens 3. If | F _G2 / F | is less than the lower limit, the ratio of the positive refractive power or the negative refractive power of the second lens group to the refractive power of the imaging lens 3 becomes too large. As a result, the lateral chromatic aberration generated by the imaging lens 3 alone becomes too large, and the chromatic aberration generated by the objective lens cannot be canceled out. In addition to this, the Petzval sum is also increased, so that the curvature of field and coma are deteriorated. In general, each aberration changes when the position of a lens having refractive power is changed. If | F _G2 / F | is less than the lower limit value, the refractive power of the second lens group is large, and therefore aberrations other than chromatic aberration are deteriorated when the second lens group is decentered.

  Furthermore, since the microscope optical system according to the present embodiment is designed with a compensation-type design concept, the number of lenses constituting the objective lens can be greatly reduced, and a compensation-free design concept Compared with the microscope optical system designed in (1), it can be manufactured at low cost. Therefore, according to the microscope optical system according to the present embodiment, good aberration performance can be realized at low cost even when the distance between the objective lens and the imaging lens is large.

Hereinafter, a more desirable configuration of the microscope optical system will be described.
The focal length of the second lens group of the imaging lens 3 is preferably a negative value. In the imaging lens 3, in the first lens group having a positive refractive power, the refraction angle of the light beam is relatively large for the short wavelength light, and the focal length is relatively small for the short wavelength light. A long wavelength light has a relatively small refraction angle, and a long wavelength light has a relatively large focal length. As a result, in the first lens group, negative lateral chromatic aberration occurs with respect to short-wavelength light, and positive lateral chromatic aberration occurs with long-wavelength light. Since this is the same for the objective lens, it is desirable to generate lateral chromatic aberration in the opposite direction to the lateral chromatic aberration generated in the first lens group in the entire imaging lens 3. Note that, as the intermediate length (that is, the distance between the objective lens and the imaging lens 3) is longer, the light ray height in the first lens group becomes higher, so that a larger chromatic aberration of magnification occurs in the first lens group. Become. For this reason, when the intermediate length is long, it is particularly desirable to make the refractive power of the second lens group negative so that the focal length on the short wavelength side of the imaging lens 3 is larger than the focal length on the long wavelength side. Thereby, the lateral chromatic aberration generated in the first lens group can be corrected.

  In order to make the refractive power of the second lens group negative and to reduce the Petzval sum of the second lens group, it is desirable to make the refractive index of the negative lens larger than the refractive index of the positive lens. Further, in order to correct chromatic aberration, a combination of a high dispersion negative lens and a low dispersion positive lens is desirable. Therefore, the second lens group includes a negative lens made of a glass material corresponding to the upper right area (small Abbe number and high refractive index) on the glass map, and the lower left area (large Abbe number on the glass map). And a positive lens made of a glass material corresponding to a small refractive index).

It is desirable that the microscope optical system satisfies the following conditional expressions (3) to (7). Here, L is the distance from the lens surface closest to the image side of the first lens group of the imaging lens 3 to the lens surface closest to the object side of the second lens group of the imaging lens 3. ν _mean is the average value of the Abbe number of the positive lens in the second lens group and the Abbe number of the negative lens in the second lens group. Δν is the difference between the Abbe number of the positive lens in the second lens group and the Abbe number of the negative lens in the second lens group. PR is the exit pupil radius of the objective lens. CH is the ray height of the principal ray incident on the maximum image height position on the image plane on the most object side surface of the first lens group. E 1 is the effective diameter of the first lens group of the imaging lens 3. The effective diameter of the first lens group is twice the maximum ray height in the first lens group of the rays that contribute to image formation.
L / F ≦ 0.6 (4)
Δν ≦ 20 (5)
0.45 <CH / PR <1.6 (6)
0.06 <E1 / F <0.12 (7)

Conditional expression (3) is an expression that prescribes the amount of lateral chromatic aberration generated in the imaging lens 3.
If the lens has a value outside the range shown in the conditional expression (3), the lateral chromatic aberration generated by the imaging lens 3 alone becomes large and cannot be canceled out with the chromatic aberration generated by the objective lens.

  Conditional expression (4) defines the distance between the lens groups of the imaging lens 3. When L / F exceeds the upper limit value, the off-axis ray height when entering the second lens group of the imaging lens 3 becomes extremely high. For this reason, the lateral chromatic aberration generated in the imaging lens 3 becomes too large.

  Conditional expression (5) defines the Abbe number difference between the positive lens and the negative lens constituting the cemented lens of the imaging lens 3. In the imaging lens 3 that satisfies the conditional expression (2), the absolute values of the refractive power of the positive lens and the negative lens constituting the cemented lens are close to each other. For this reason, when Δν exceeds the upper limit value, the cemented lens excessively corrects the lateral chromatic aberration that occurs depending on the distance between the lens groups of the imaging lens 3 defined by the conditional expression (4).

  Conditional expression (6) is an expression defining the ratio of the ray height of the principal ray in the first lens group and the exit pupil radius of the objective lens. The higher the chief ray height incident on the lens, the greater the angular deviation that occurs between chief rays of different wavelengths, and the greater the chromatic aberration of magnification that occurs. In addition, since the refractive power of the second lens group of the imaging lens 3 is small, the light beam height in the first lens group of the imaging lens 3 is approximately the same as the light beam height in the second lens group. Under such conditions, if CH / PR exceeds the upper limit value, the chromatic aberration of magnification generated in the objective lens 1 cannot be corrected by the imaging lens 3 and the correction becomes insufficient. On the other hand, if CH / PR falls below the lower limit value, the chromatic aberration of magnification generated in the objective lens 1 is excessively corrected by the imaging lens 3, and chromatic aberration remains.

  Furthermore, by satisfying the conditional expression (6), the ray height of the off-axis principal ray is within an appropriate range, so that the coma aberration can be favorably corrected by the imaging lens 3. When CH / PR exceeds the upper limit value, the bending of the upper marginal ray of the off-axis light beam becomes steep, and the off-axis coma aberration is significantly deteriorated. On the other hand, when CH / PR falls below the lower limit value, the bending of the lower marginal ray of the off-axis light beam becomes gentle, so that the off-axis coma aberration is insufficiently corrected by the first lens unit.

Conditional expression (7) defines the ratio of the effective diameter to the focal length of the imaging lens 3. By satisfying conditional expression (7), it is possible to reduce deterioration of the exit NA of the off-axis light beam with respect to the exit NA of the on-axis light beam. If E1 / F is less than the lower limit, the first lens group of the imaging lens 3 has insufficient diameter, and the exit NA of the off-axis light beam is significantly deteriorated. For this reason, the amount of light in a portion with a high image height is reduced, resulting in unevenness in the amount of light. On the other hand, if E1 / F exceeds the upper limit value, the lens becomes so large that a portion through which the light beam does not pass is formed. For this reason, the processing precision of a lens will fall. In addition, processing of the lens frame becomes difficult.
Hereinafter, examples of the above-described microscope optical system will be specifically described.

[Example 1]
FIG. 4 is a cross-sectional view of the imaging lens 10 according to the first embodiment. FIG. 5 is a cross-sectional view of a microscope optical system 11 including the objective lens 1 and the imaging lens 10. FIG. 6 is a sectional view of a microscope optical system 12 including the objective lens 2 and the imaging lens 10. The microscope according to the present embodiment is different from the microscope 100 shown in FIG. 1 in that the imaging lens 10 is provided instead of the imaging lens 3. Other configurations are the same as those of the microscope 100.

  The imaging lens 10 is an imaging lens for a microscope that is used in combination with the objective lens 1 or the objective lens 2. As shown in FIG. 4, the imaging lens 10 has a three-lens two-group configuration, and in order from the object side, a first lens group G21 having a positive refractive power, a positive lens (lens L22), and a negative lens ( The second lens group G22 which is a cemented lens CL21 made of a lens L23). Both the lens L22 and the lens L23 are meniscus lenses having a concave surface facing the image side. The first lens group G21 is a meniscus lens (lens L21) having a concave surface directed toward the object side, and is composed of a single lens.

Various data of the imaging lens 10 is as follows. The reference wavelength is d line (587.56 nm).
F = 225 mm, F _G2 = 1436.1388 mm, L = 38.7829 mm, ν _mean = 50.955, Δν = 7.45

The lens data of the imaging lens 10 is as follows. Note that INFINITY in the lens data indicates infinity (∞).
Imaging lens 10
srd nd νd
21 -236.3927 5.0000 1.51633 64.14
22 -90.6706 38.7829
23 43.2002 4.0000 1.72916 54.68
24 88.8999 4.0000 1.67003 47.23
25 39.7479 176.6471

  The surfaces indicated by the surface numbers s21 and s25 are the first surface and the final surface of the imaging lens 10, respectively. The surface interval d25 indicates the distance from the lens surface (final surface) closest to the image side of the imaging lens 10 to the image surface IP.

Various data of the microscope optical system 11 are as follows. NA _I is the numerical aperture on the image side, and IM. H is the image height.
D = 67.5 mm, NA _I = 0.025, IM. H = 10mm, CH = 2.8153mm, E1 = 18.8mm

Various data of the microscope optical system 12 is as follows.
D = 67.5 mm, NA _I = 0.01625, IM. H = 10mm, CH = 3.45117mm, E1 = 13.8mm

The microscope optical system 11 and the microscope optical system 12 satisfy the conditional expressions (1) to (7) as shown below.
(1) D / F = 0.3
(2) | F _G2 /F|=6.382839
(4) L / F = 0.172
(5) Δν = 7.45
(6) CH / PR = 0.4849 (microscope optical system 11)
(6) CH / PR = 0.7218 (microscope optical system 12)
(7) E1 / F = 0.084 (microscope optical system 11)
(7) E1 / F = 0.061 (microscope optical system 12)

  FIG. 7 is an aberration diagram of the microscope optical system 11, and FIG. 8 is an aberration diagram of the microscope optical system 12. Both are aberration diagrams on the object plane. FIG. 7A and FIG. 8A are spherical aberration diagrams. 7 (b) and 8 (b) are astigmatism diagrams. 7 (c) and 8 (c) are distortion diagrams. FIGS. 7D and 8D are chromatic aberration diagrams of magnification. FIG. 7E and FIG. 8E are coma aberration diagrams. In the figure, “M” indicates a meridional component, and “S” indicates a sagittal component.

[Example 2]
FIG. 9 is a cross-sectional view of the imaging lens 20 according to the second embodiment. FIG. 10 is a cross-sectional view of a microscope optical system 21 including the objective lens 1 and the imaging lens 20. FIG. 11 is a cross-sectional view of a microscope optical system 22 including the objective lens 2 and the imaging lens 20. The microscope according to this embodiment is different from the microscope 100 shown in FIG. 1 in that the imaging lens 20 is provided instead of the imaging lens 3. Other configurations are the same as those of the microscope 100.

  The imaging lens 20 is an imaging lens for a microscope that is used in combination with the objective lens 1 or the objective lens 2. As shown in FIG. 9, the imaging lens 20 has a two-group configuration of three lenses, and in order from the object side, a first lens group G21 having a positive refractive power, a positive lens (lens L22), and a negative lens ( The second lens group G22 which is a cemented lens CL21 made of a lens L23). The lens L22 is a biconvex lens, and the lens L23 is a biconcave lens. The first lens group G21 is a planoconvex lens (lens L21) having a convex surface directed toward the object side, and is composed of a single lens. The focal length of the second lens group G22 is a negative value.

Various data of the imaging lens 20 are as follows. The reference wavelength is d line (587.56 nm).
F = 225 mm, F _G2 = −3680.4729 mm, L = 118.9243 mm, ν _mean = 44.54, Δν = 7.56

The lens data of the imaging lens 20 is as follows.
Imaging lens 20
srd nd νd
21 169.7403 5.0000 1.72916 54.68
22 INFINITY 118.9243
23 48.7656 4.0000 1.66672 48.32
24 -204.0993 4.0000 1.88300 40.76
25 64.2714 96.5057

Various data of the microscope optical system 21 are as follows.
D = 112.5 mm, NA _I = 0.025, IM. H = 10mm, CH = 4.83339mm, E1 = 22.4mm

Various data of the microscope optical system 22 is as follows.
D = 112.5 mm, NA _I = 0.01625, IM. H = 10mm, CH = 5.4721mm, E1 = 17.6mm

The microscope optical system 21 and the microscope optical system 22 satisfy the conditional expressions (1) to (7) as shown below.
(1) D / F = 0.500
(2) | F _G2 /F|=16.35766
(4) L / F = 0.529
(5) Δν = 7.56
(6) CH / PR = 0.8325 (microscope optical system 21)
(6) CH / PR = 1.1444 (microscope optical system 22)
(7) E1 / F = 0.100 (microscope optical system 21)
(7) E1 / F = 0.078 (microscope optical system 22)

  12 is an aberration diagram of the microscope optical system 21, and FIG. 13 is an aberration diagram of the microscope optical system 22. Both are aberration diagrams on the object plane. FIGS. 12A and 13A are spherical aberration diagrams. 12B and 13B are astigmatism diagrams. 12 (c) and 13 (c) are distortion diagrams. FIGS. 12D and 13D are chromatic aberration diagrams of magnification. 12E and 13E are coma aberration diagrams.

[Example 3]
FIG. 14 is a cross-sectional view of the imaging lens 30 according to the third embodiment. FIG. 15 is a cross-sectional view of a microscope optical system 31 including the objective lens 1 and the imaging lens 30. FIG. 16 is a cross-sectional view of a microscope optical system 32 including the objective lens 2 and the imaging lens 30. The microscope according to the present embodiment is different from the microscope 100 shown in FIG. 1 in that an imaging lens 30 is provided instead of the imaging lens 3. Other configurations are the same as those of the microscope 100.

  The imaging lens 30 is an imaging lens for a microscope that is used in combination with the objective lens 1 or the objective lens 2. As shown in FIG. 14, the imaging lens 30 has a two-group configuration of three lenses, and in order from the object side, a first lens group G21 having a positive refractive power, a positive lens (lens L22), and a negative lens ( The second lens group G22 which is a cemented lens CL21 made of a lens L23). The lens L22 is a biconvex lens, and the lens L23 is a biconcave lens. The first lens group G21 is a planoconvex lens (lens L21) having a convex surface directed toward the image side, and includes a single lens. The focal length of the second lens group G22 is a negative value.

Various data of the imaging lens 30 is as follows. The reference wavelength is d line (587.56 nm).
F = 225 mm, F _G2 = -1273.3892 mm, L = 134.9963 mm, ν _mean = 45.82, Δν = 10.120

The lens data of the imaging lens 30 is as follows.
Imaging lens 30
srd nd νd
21 INFINITY 5.0000 1.52249 59.84
22 -119.4976 134.9963
23 36.7792 4.0000 1.65844 50.88
24 -245.2091 4.0000 1.88300 40.76
25 45.6407 80.4337

Various data of the microscope optical system 31 are as follows.
D = 157.5 mm, NA _I = 0.025, IM. H = 10mm, CH = 6.84681mm, E1 = 26.8mm

Various data of the microscope optical system 32 are as follows.
D = 157.5 mm, NA _I = 0.01625, IM. H = 10mm, CH = 7.48613mm, E1 = 21.8mm

The microscope optical system 31 and the microscope optical system 32 satisfy the conditional expressions (1) to (7) as shown below.
(1) D / F = 0.700
(2) | F _G2 /F|=5.659507
(4) L / F = 0.600
(5) Δν = 10.120
(6) CH / PR = 1.1793 (microscope optical system 31)
(6) CH / PR = 1.5656 (microscope optical system 32)
(7) E1 / F = 0.119 (microscope optical system 31)
(7) E1 / F = 0.097 (microscope optical system 32)

  FIG. 17 is an aberration diagram of the microscope optical system 31, and FIG. 18 is an aberration diagram of the microscope optical system 32. Both are aberration diagrams on the object plane. 17 (a) and 18 (a) are spherical aberration diagrams. FIG. 17B and FIG. 18B are astigmatism diagrams. 17 (c) and 18 (c) are distortion diagrams. FIGS. 17D and 18D are chromatic aberration diagrams of magnification. FIG. 17E and FIG. 18E are coma aberration diagrams.

[Example 4]
FIG. 19 is a cross-sectional view of the imaging lens 40 according to the fourth embodiment. FIG. 20 is a cross-sectional view of a microscope optical system 41 including the objective lens 1 and the imaging lens 40. FIG. 21 is a cross-sectional view of a microscope optical system 42 including the objective lens 2 and the imaging lens 40. The microscope according to the present embodiment is different from the microscope 100 shown in FIG. 1 in that an imaging lens 40 is provided instead of the imaging lens 3. Other configurations are the same as those of the microscope 100.

  The imaging lens 40 is an imaging lens for a microscope that is used in combination with the objective lens 1 or the objective lens 2. As shown in FIG. 19, the imaging lens 40 has a three-lens two-group configuration, and in order from the object side, a first lens group G21 having a positive refractive power, a positive lens (lens L22), and a negative lens ( The second lens group G22 which is a cemented lens CL21 made of a lens L23). The lens L22 is a plano-convex lens having a convex surface facing the image side, and the lens L23 is a meniscus lens having a concave surface facing the object side. The first lens group G21 is a planoconvex lens (lens L21) having a convex surface directed toward the object side, and is composed of a single lens. The focal length of the second lens group G22 is a negative value.

Various data of the imaging lens 40 is as follows. The reference wavelength is d line (587.56 nm).
F = 225 mm, F _G2 = −1846.6116 mm, L = 16.2808 mm, ν _mean = 54.855, Δν = 0.090

The lens data of the imaging lens 40 is as follows.
Imaging lens 40
srd nd νd
21 115.3180 5.0000 1.57135 52.95
22 INFINITY 16.2808
23 INFINITY 4.0000 1.51823 58.90
24 -59.6001 4.0000 1.69350 50.81
25 -291.0643 199.1492

Various data of the microscope optical system 41 is as follows.
D = 67.5 mm, NA _I = 0.025, IM. H = 10mm, CH = 2.81852mm, E1 = 18.4mm

Various data of the microscope optical system 42 is as follows.
D = 67.5 mm, NA _I = 0.01625, IM. H = 10mm, CH = 3.45536mm, E1 = 13.6mm

The microscope optical system 41 and the microscope optical system 42 satisfy the conditional expressions (1) to (7) as shown below.
(1) D / F = 0.300
(2) | F _G2 / F | = 8.20716
(4) L / F = 0.072
(5) Δν = 8.090
(6) CH / PR = 0.4855 (microscope optical system 41)
(6) CH / PR = 0.7227 (microscope optical system 42)
(7) E1 / F = 0.082 (microscope optical system 41)
(7) E1 / F = 0.060 (microscope optical system 42)

  FIG. 22 is an aberration diagram of the microscope optical system 41, and FIG. 23 is an aberration diagram of the microscope optical system 42. Both are aberration diagrams on the object plane. 22A and 23A are spherical aberration diagrams. 22 (b) and 23 (b) are astigmatism diagrams. 22 (c) and 23 (c) are distortion diagrams. FIGS. 22D and 23D are chromatic aberration diagrams of magnification. 22E and 23E are coma aberration diagrams.

[Example 5]
FIG. 24 is a cross-sectional view of the imaging lens 50 according to the fifth embodiment. FIG. 25 is a cross-sectional view of a microscope optical system 51 including the objective lens 1 and the imaging lens 50. FIG. 26 is a cross-sectional view of a microscope optical system 52 including the objective lens 2 and the imaging lens 50. The microscope according to the present embodiment is different from the microscope 100 shown in FIG. 1 in that an imaging lens 50 is provided instead of the imaging lens 3. Other configurations are the same as those of the microscope 100.

  The imaging lens 50 is a microscope imaging lens used in combination with the objective lens 1 or the objective lens 2. As shown in FIG. 24, the imaging lens 50 has a two-group configuration of three lenses, and in order from the object side, a first lens group G21 having a positive refractive power, a positive lens (lens L22), and a negative lens ( The second lens group G22 which is a cemented lens CL21 made of a lens L23). The lens L22 is a biconvex lens, and the lens L23 is a biconcave lens. The first lens group G21 is a meniscus lens (lens L21) having a concave surface directed toward the image side, and is composed of a single lens. The focal length of the second lens group G22 is a negative value.

Various data of the imaging lens 50 is as follows. The reference wavelength is d line (587.56 nm).
F = 225 mm, F _G2 = -14593.3599 mm, L = 129.1876 mm, ν _mean = 62.88, Δν = 14.70

The lens data of the imaging lens 50 is as follows.
Imaging lens 50
srd nd νd
21 65.5542 5.0000 1.54814 45.79
22 127.8419 129.1876
23 34.0475 4.0000 1.48749 70.23
24 -52.4098 4.0000 1.69680 55.53
25 61.8930 86.2424

Various data of the microscope optical system 51 is as follows.
D = 112.5 mm, NA _I = 0.025, IM. H = 10mm, CH = 0.84156mm, E1 = 22.2mm

Various data of the microscope optical system 51 is as follows.
D = 112.5 mm, NA _I = 0.01625, IM. H = 10mm, CH = 5.48251mm, E1 = 17.4mm

The microscope optical system 51 and the microscope optical system 52 satisfy the conditional expressions (1) to (7) as shown below.
(1) D / F = 0.500
(2) | F _G2 /F|=64.859378
(4) L / F = 0.574
(5) Δν = 14.70
(6) CH / PR = 0.8339 (microscope optical system 51)
(6) CH / PR = 1.1466 (microscope optical system 52)
(7) E1 / F = 0.099 (microscope optical system 51)
(7) E1 / F = 0.077 (microscope optical system 52)

  FIG. 27 is an aberration diagram of the microscope optical system 51, and FIG. 28 is an aberration diagram of the microscope optical system 52. Both are aberration diagrams on the object plane. FIGS. 27A and 28A are spherical aberration diagrams. FIG. 27B and FIG. 28B are astigmatism diagrams. 27 (c) and 28 (c) are distortion diagrams. FIGS. 27 (d) and 28 (d) are chromatic aberration diagrams of magnification. FIGS. 27E and 28E are coma aberration diagrams.

[Example 6]
FIG. 29 is a cross-sectional view of the imaging lens 60 according to the sixth embodiment. FIG. 30 is a cross-sectional view of a microscope optical system 61 including the objective lens 1 and the imaging lens 60. FIG. 31 is a cross-sectional view of a microscope optical system 62 including the objective lens 2 and the imaging lens 60. The microscope according to the present embodiment is different from the microscope 100 shown in FIG. 1 in that an imaging lens 60 is provided instead of the imaging lens 3. Other configurations are the same as those of the microscope 100.

  The imaging lens 60 is an imaging lens for a microscope that is used in combination with the objective lens 1 or the objective lens 2. As shown in FIG. 29, the imaging lens 60 has a three-lens two-group configuration, and in order from the object side, a first lens group G21 having a positive refractive power, a positive lens (lens L22), and a negative lens ( The second lens group G22 which is a cemented lens CL21 made of a lens L23). The lens L22 is a biconvex lens, and the lens L23 is a biconcave lens. The first lens group G21 is a planoconvex lens (lens L21) having a convex surface directed toward the object side, and is composed of a single lens. The focal length of the second lens group G22 is a negative value.

Various data of the imaging lens 60 is as follows. The reference wavelength is d line (587.56 nm).
F = 225 mm, F _G2 = −5590.6003 mm, L = 117.8395 mm, ν _mean = 60.52, Δν = 19.42

The lens data of the imaging lens 60 is as follows.
Imaging lens 60
srd nd νd
21 121.0107 5.0000 1.51823 58.90
22 INFINITY 117.8395
23 42.0346 4.0000 1.48749 70.23
24 -100.4839 4.0000 1.69350 50.81
25 67.0196 97.5905

Various data of the microscope optical system 61 is as follows.
D = 157.5 mm, NA _I = 0.025, IM. H = 10mm, CH = 6.86114mm, E1 = 26.4mm

Various data of the microscope optical system 61 is as follows.
D = 157.5 mm, NA _I = 0.01625, IM. H = 10mm, CH = 7.50253mm, E1 = 21.6mm

The microscope optical system 61 and the microscope optical system 62 satisfy the conditional expressions (1) to (7) as shown below.
(1) D / F = 0.524
(2) | F _G2 /F|=24.84711
(4) L / F = 0.700
(5) Δν = 19.42
(6) CH / PR = 1.1818 (microscope optical system 61)
(6) CH / PR = 1.5681 (microscope optical system 62)
(7) E1 / F = 0.117 (microscope optical system 61)
(7) E1 / F = 0.096 (microscope optical system 62)

  FIG. 32 is an aberration diagram of the microscope optical system 61, and FIG. 33 is an aberration diagram of the microscope optical system 62. Both are aberration diagrams on the object plane. FIG. 32A and FIG. 33A are spherical aberration diagrams. 32 (b) and 33 (b) are astigmatism diagrams. 32 (c) and 33 (c) are distortion diagrams. FIGS. 32D and 33D are chromatic aberration diagrams of magnification. 32 (e) and 33 (e) are coma aberration diagrams.

DESCRIPTION OF SYMBOLS 1, 2 Objective lens 3 Imaging lens 4 Eyepiece lens 5 Camera 6, 7 Light source 8 Stage 9 Revolver 10, 20, 30, 40, 50, 60 Imaging lens 11, 12, 21, 22, 31, 32, 41, 42, 51, 52, 61, 62
Microscope optical system 100 Microscope CG Cover glass IP Image plane

Claims (7)

An infinite correction objective lens,
An imaging lens,
The imaging lens, in order from the object side,
A first lens group having a positive refractive power;
A second lens group that is a cemented lens composed of a positive lens and a negative lens,
The distance of D from the cylinder with surface of the objective lens to the lens surface on the most object side of the imaging lens, the F and the focal length of the imaging lens, and the F _G2 focal length of the second lens group When the following conditional expression
0.3 ≦ D / F ≦ 0.7 (1)
5 ≦ | F _G2 / F | (2)
A microscope optical system characterized by satisfying In the microscope optical system according to claim 1,
L is the distance from the lens surface closest to the image side of the first lens group to the lens surface closest to the object side of the second lens group, and ν _mean is the Abbe number of the positive lens and the Abbe number of the negative lens When the average value of
A microscope optical system characterized by satisfying In the microscope optical system according to claim 1 or 2,
When Δν is the difference between the Abbe number of the positive lens and the Abbe number of the negative lens, the following conditional expression L / F ≦ 0.6 (4)
Δν ≦ 20 (5)
A microscope optical system characterized by satisfying The microscope optical system according to any one of claims 1 to 3,
The microscope optical system characterized in that the focal length of the second lens group is a negative value. The microscope optical system according to any one of claims 1 to 4,
When PR is the exit pupil radius of the objective lens and CH is the ray height of the principal ray incident on the maximum image height position on the most object side surface of the first lens group, the following conditional expression
0.45 <CH / PR <1.6 (6)
A microscope optical system characterized by satisfying The microscope optical system according to any one of claims 1 to 5,
When E1 is the effective diameter of the first lens group, the following conditional expression
0.06 <E1 / F <0.12 (7)
A microscope optical system characterized by satisfying A microscope comprising the microscope optical system according to any one of claims 1 to 6.