JPH07239440A - Magnifying lens for microscope - Google Patents

Abstract

PURPOSE:To provide a magnifying lens capable of increasing an magnification of a microscope having a high performance with simple and compact optical constitution by arranging plural lens groups into the convergent luminous flux formed by an objective optical system for the microscope and converting a space image to a prescribed magnification. CONSTITUTION:The microscope is provided with the magnifying lens 7 which converts the luminous flux from an object 5 to be observed to the convergent luminous flux and increases the magnification of the objective optical system 6 for the microscope forming the space image I0 of an object 5 to be observed to the prescribed magnification. This magnifying lens 7 has the plural lens groups of negative refracting powers which are independently corrected in aberrations. The space image I0 is converted to the prescribed magnification by arranging the plural lens groups G1, G2 in the convergent luminous flux formed by the objective optical system 6 for the microscope. As a result, there is no more need for providing the objective optical system with many relay systems for obtaining the large magnification in series and the large magnification is obtd. while the size of the optical system constituting the microscope is reduced and the performance thereof is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system for converting the magnification of a microscope into a predetermined magnification.

[0002]

2. Description of the Related Art A microscope of this type is as shown in FIG.
First, the sample 5 placed on a stage (not shown) is subjected to transmitted illumination or epi-illumination by an illumination system (not shown). The light from the illuminated sample 5 is subjected to converging action by the objective lens 6, after the enlarged image I ₀ of the sample 5 (aerial image) is formed, which magnified image I ₀ at a predetermined ratio larger The second magnified image I ₁₀ is re-formed by the relay system 11 that operates. A CCD or the like as an image pickup element is arranged on the enlarged image I _10. The output from the CCD or the like is image-processed by an image processing system (not shown) and electrically connected to the image processing system. Enlarged image I ₁₀ via the display (CRT monitor), etc.
Image is displayed. There is also a microscope in which an eyepiece lens is arranged behind the magnified image I ₁₀ instead of a CCD or the like as an image pickup element, and the magnified image I ₁₀ is magnified and observed through this eyepiece lens.

In the microscope as shown in FIG. 11, the image formed by the objective lens 6 is changed in order to increase the magnification.
The image is enlarged and re-imaged by the relay system 11.

[0004]

Here, when it is desired to increase the magnifying power higher than that of the microscope of FIG. 11, the magnified image I ₁₀ is magnified to a predetermined magnification behind the relay system 11 as shown in FIG. To form a third magnified image I ₂₀
It is conceivable that the relay system 12 is arranged and the CCD or the like is arranged at the position of the third enlarged image I ₂₀ . Furthermore, FIG.
If it is desired to increase the enlargement ratio higher than that of the second microscope, the third relay system 12 and the rear side of the third relay system 12 are not shown.
It is conceivable to magnify the magnified image I ₂₀ of No. 1 to a predetermined magnification, arrange a third relay system that forms a fourth magnified image, and arrange a CCD or the like at the position of the fourth magnified image.

However, it is conceivable to arrange a plurality of relay systems in series in order to increase the magnifying power as described above, but with the arrangement of a plurality of relay systems in series, the total length of the microscope is inevitably large. There is a problem that the device becomes large in size because it becomes very long. Further, in order to obtain good image forming performance while shortening the total length of each relay system itself, the lens configuration in each relay system becomes complicated and expensive.

Further, when a plurality of relay systems are arranged in series, not only the entire microscope becomes longer and the apparatus becomes larger, but also the lens barrel structure is formed in terms of strength and miniaturization of the entire apparatus. It is necessary to devise it enough. Furthermore, in recent years, the image pickup device including the image pickup device and the image processing system has become remarkably small in accordance with the technical progress of the image pickup device such as CCD and the image processing system, so that the image pickup device can be downsized. is there. However, if a plurality of relay systems are used in order to increase the magnification, there is a problem in that miniaturization of the optical system involves a considerable difficulty in principle.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a high-performance microscope magnifying lens capable of increasing the magnifying power of a microscope with an extremely simple and compact optical structure. And

[0008]

To achieve the above object, the present invention converts a light beam from an object 5 to be observed into a convergent light beam and aerial images (I ₀ , I _{10) of the} object 5 to be observed. In the magnifying lens 7 for magnifying the magnification of the objective optical system for a microscope (6, or 6 and 11) to a predetermined magnification, the magnifying lens 7 is a lens group of negative refracting power whose aberrations are independently corrected. By arranging the plurality of lens groups (G ₁ , G ₂ ) in the convergent light beam formed by the microscope objective optical system 7, the aerial image (I ₀ , I ₁₀ ) is predetermined. It is configured to be converted into a magnification of.

Based on the above basic structure, each lens group (G ₁ , G ₂ ) preferably comprises a positive lens and a negative lens. The positive lens is composed of a meniscus lens having a concave surface facing the object side, the negative lens is composed of a biconcave lens, and the refractive index of the positive lens in each lens group is n _P , The Abbe number of the positive lens in each lens group is ν _P , the focal length of the positive lens in each lens group is f _P , the refractive index of the negative lens in each lens is n _N , and When the Abbe number of the negative lens is ν _N and the focal length of the negative lens in each of the lens groups is f _N , (1) 1.1 <n _P / n _N <1.4 (2) 2.0 <ν _N / ν _P < 3.5 (3) −0.95 <(n _N × ν _N × f _N ) / (n _P × ν _P
It is more desirable that xf _P ) <− 0.8 is satisfied.

[0010]

[Operation] In order to obtain a large magnifying power without increasing the size of the optical configuration of the microscope, the present invention is such that, in the convergent light beam formed by the objective optical system, the negative refracting power of independently corrected aberration By arranging a magnifying lens having a plurality of lens groups, in principle, it is not necessary to provide a large number of relay systems in series in order to obtain a large magnifying power, and the optical configuration of the microscope can be made compact and high performance can be achieved. While trying, it is possible to obtain a large magnification.

This is because the objective optical system of the microscope is multiplied by the magnification, the numerical aperture NA on the image side (aerial image side) of this objective optical system is small, and the angle of view is extremely narrow.
Therefore, aberrations due to off-axis light flux (astigmatism, coma)
Since there is little load on the correction of (1) and the correction of the aberration (spherical aberration) due to the axial ray, even if each lens group in the magnifying lens is configured with an extremely small number of lenses, in principle good imaging performance is ensured. Can also obtain a large magnification.

The principle of the present invention will be briefly described with reference to FIG. As shown in FIG. 3, the magnifying lens 7 of the present invention is arranged in a light beam converged by an objective optical system (not shown), and has a negative refractive power of the first lens group G ₁
And a second lens group G ₁ having a negative refracting power. The original aerial image I ₀ formed by the objective optical system (not shown) is formed at the position P _0, and the enlarged image I ₁ of the aerial image I ₀ is formed at the position P ₁ by the diverging action of the first lens group G _1. It Then, the magnified image I ₂ of the magnified image I ₁ is moved to the position P ₂ by the diverging action of the second lens group G ₂ which is arranged at a position separated from the first lens group G _{1 by} a predetermined distance in the optical axis direction. It is formed. Therefore, the first lens group G1 and the second lens group G
If the magnification of ₂ is β ₁ and β ₂ , respectively, the magnified image I ₂ formed at the position P ₂ is magnified β ₁ × β ₂ times as much as the original aerial image I ₀ formed by the objective optical system. Thus, the method of adding the magnifying lens 7 of the present invention to the convergent light flux of the objective optical system to obtain a predetermined magnification is more preferable than the method of adding one relay system to the microscope to obtain a predetermined magnification. It can be understood that it can be made compact with a simple structure.

In FIG. 3, in order to simplify the explanation of the principle of the magnifying lens 7 of the present invention, the case where the magnifying lens 7 has a two-group structure has been described. A magnifying lens having three or more lens groups may be arranged in the convergent light beam formed by the objective optical system. In order to achieve a sufficient correction for chromatic aberration while achieving compactness, it is desirable that each lens group has a lens configuration including a negative lens and a positive lens. Further, it is more preferable that the positive lens and the negative lens forming each lens group in the magnifying lens are cemented to each other. In this case, it is advantageous for the eccentricity error in manufacturing the magnifying lens. There are advantages.

Further, in order to give each lens group in the magnifying lens of the present invention a sufficient aberration correction function, each lens group in the magnifying lens should be a positive meniscus lens with a concave surface facing the object side. A biconcave negative lens is used, the refractive index of the positive lens in each lens group is n _P , the Abbe number of the positive lens in each lens group is ν _P , and the focal length of the positive lens in each lens group is f _P , Where the refractive index of the negative lens in each lens is n _N , the Abbe number of the negative lens in each lens group is ν _N , and the focal length of the negative lens in each lens group is f _N , (1) 1.1 < n _P / n _N <1.4 (2) 2.0 <ν _N / ν _P <3.5 (3) −0.95 <(n _N × ν _N × f _N ) / (n _P × ν _P
It is desirable that xf _P ) <− 0.8 is satisfied.

If the upper limit of conditional expression (1) is exceeded, there is no existing glass material and it cannot be realized. On the contrary, if the lower limit value of the conditional expression (1) is exceeded, the difference in refractive index becomes too small, the spherical aberration is overcorrected, and it becomes difficult to correct coma aberration. It is more preferable to set the upper limit of conditional expression (1) to 1.25, that is, n _P / n _N <1.25. In this case, there is an advantage that the balance of correction of spherical aberration and curvature of field can be further improved.

When the upper limit of conditional expression (2) is exceeded, axial chromatic aberration is insufficiently corrected, and even if the positive lens and the negative lens in each lens group have a sufficient axial chromatic aberration correction function, In this case, spherical aberration is overcorrected, which is not preferable. On the other hand, if the lower limit of conditional expression (2) is exceeded, axial chromatic aberration will be overcorrected, and even if the positive lens and the negative lens in each lens group have a sufficient axial chromatic aberration correction function, In this case, spherical aberration is insufficiently corrected, which is not preferable. It is more preferable to set the upper limit of conditional expression (2) to 3.2, that is, ν _N / ν _P <3.2.
In this case, there is an advantage that the correction balance between spherical aberration and chromatic aberration can be further improved.

If the upper limit of conditional expression (3) is exceeded, both axial chromatic aberration and lateral chromatic aberration will be overcorrected. Conversely, if the lower limit of conditional expression (3) is exceeded, axial chromatic aberration and lateral chromatic aberration will be excessive. Both are undercorrected. More preferably, the lower limit of conditional expression (3) is -0.9, that is, -0.9 <(n _N × ν _N
Xf _N ) / (n _P × ν _P × f _P ). In this case, there is an advantage that the balance of correction of axial chromatic aberration and lateral chromatic aberration can be further improved.

[0018]

FIG. 1 shows a schematic structure of a magnifying lens of the present invention incorporated in a microscope. An embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the specimen 5 as the observed object held on the stage 4
Are transilluminated by the transillumination system (1-3). In this transmission illumination system, a light flux from a halogen lamp 1 as a light source is condensed by a collector lens 2 and uniformly illuminates a sample 5 via a condenser lens 3.

The light flux from the sample 5 which is transmitted and illuminated by the transmissive illumination systems (1 to 3) in this way is converted into a convergent light flux by the objective lens 6 to form a spatial image I ₀ . Here, in the convergent light flux formed by the objective lens 6, the magnifying lens 7 having a negative refracting power as a whole is arranged. The magnifying lens 7 has, in order from the object side, a first lens group G ₁ having a negative refractive power and a second lens group G ₂ having a negative refractive power as well. This first lens group G ₁
As described above with reference to FIG. 3, the aerial image I ₀ is used as an object to form a magnified image I _1, and the second lens group G
_2, an aerial image I ₁ as an object to form a magnified image I _2. Since each lens group has its aberration corrected independently, each magnified image (I ₁ , I ₂ ) is good.

At the position of this magnified image I ₂
A CCD 8 as a seed is arranged, and an output photoelectrically converted by the CCD 8 is image-processed by an image processing system 9. This image processing signal is displayed on the CRT monitor 1 as a display unit.
0, and finally the enlarged image I ₂ is displayed on the CRT monitor 10.
Is displayed at. FIG. 2 shows a cross-sectional structure of the magnifying lens incorporated in FIG. As shown in FIG. 2, the first lens group G ₁ and the second lens group G that constitute the magnifying lens 7
₂ is composed of a meniscus-shaped positive lens with a concave surface facing the object side, and a biconcave-shaped negative lens cemented to this, and aberrations are well corrected independently for each lens group. There is. The first lens group G ₁ is held by the first barrel 71 to form a first unit, and the second lens group G ₂ is held by the second barrel 72 to form a second unit. is doing. The outer protruding portion of the first barrel 71 and the second protruding portion
The inner protrusion of the lens barrel 72 of
The lens group G ₁ and the second lens group G ₂ are held in series along the optical axis. Since the cemented surface of each lens group has a convex surface facing the image side, the occurrence of coma is suppressed.

With the above unit configuration, if a plurality of units each including a lens group having an arbitrary imaging magnification and a lens barrel holding the lens group are arbitrarily arranged in series,
Despite its compact structure, it is possible to obtain an image with a large magnification. Next, the specifications of the magnifying lens shown in FIGS. 1 and 3 are listed in Tables 1 to 6 below. In each specification table, f _P is the focal length of the positive lens forming part of the lens group, f _N is the focal length of the negative lens forming part of the lens group, f is the focal length of the lens group, and m Is the imaging magnification of the lens group, d0 is the distance from the object (object point) to the first surface of the lens group, d3 is the distance from the final surface of the lens group to the image (image point), r is the radius of curvature, and d is Lens surface distance, ν is Abbe number,
n indicates the refractive index for the d line (587.6 nm). Table 1 (Example 1 of a lens group having a magnification of 2.5 times) f _P = 86.8, f _N = −30.3, f = −45.5, m = 2.5, d0 = −28.0 r d n ν r1 = −49.5 d1 = 2.0 n1 = 1.8052 ν1 = 25.4 r2 = -29.5 d2 = 1.0 n2 = 1.5186 ν2 = 70.0 r3 = 34.0 d3 = 67.0 n P / n n = n1 / n2 = 1.19, ν n / ν P = ν2 / ν1 = 2.99 (n _N × ν _N × f _N ) / (n _P × ν _P × f _P ) = 0.88 Table 2 (Example 2 of a lens group having a magnification of 2.5 times) f _P = 71.3, f _N = −27.9, f = − 45.1, m = 2.5, d0 = −28.0 r d n ν r1 = −56.5 d1 = 2.0 n1 = 1.7552 ν1 = 27.6 r2 = −28.0 d2 = 1.0 n2 = 1.5186 ν2 = 70.0 r3 = 30.4 d3 = 67.0 n _P / n _N = n1 / n2 = 1.15, ν _N / ν _P = ν2 / ν1 = 2.54 (n _N × ν _N × f _N ) / (n _P × ν _P × f _P ) = 0.86 Table 3 (2.5 times magnification Example of lens group 3) having f _P = 83.3, f _N = −29.8, f = −45.4, m = 2.5, d0 = −28.0 r d n ν r1 = −50.0 d1 = 2.0 n1 = 1.7950 ν1 = 28.6 r2 = −29.0 d2 = 1.0 n2 = 1.4978 ν2 = 82.5 r3 = 30.7 d3 = 67.0 n _{P / n N = n1 / n2} = 1.20, ν N / ν P = ν2 / ν1 = 2.88 (n N × ν N × f N) / (n P × ν P × f P) = 0.86 Table 4 (4.0-fold Example of a lens group having a magnification of 1) f _P = 43.9, f _N = −20.2, f = −36.3, m = 4.0, d0 = −28.0 r d n ν r1 = −36.5 d1 = 2.0 n1 = 1.7408 ν1 = 27.6 r2 = -17.6 d2 = 1.0 n2 = 1.5182 ν2 = 59.0 r3 = 26.4 d3 = 108.0 n P / n n = n1 / n2 = 1.15, ν n / ν P = ν2 / ν1 = 2.14 (n n × ν n × f _N ) / (n _P × ν _P × f _P ) = 0.86 Table 5 (Example 2 of a lens group having a magnification of 4.0) f _P = 45.5, f _N = −20.6, f = −36.5, m = 4.0 , D0 = −28.0 r d n ν r1 = −34.2 d1 = 2.0 n1 = 1.7569 ν1 = 31.6 r2 = −17.6 d2 = 1.0 n2 = 1.5186 ν2 = 70.0 r3 = 27.9 d3 = 108.0 n _P / n _N = n1 / n2 = 1.16, ν _N / ν _P = ν 2 / ν 1 = 2.22 (n _N × ν _N × f _N ) / (n _P × ν _P × f _P ) = 0.87 Table 6 (Example of lens group with 4.0 times magnification ) 3) f _P = 44.0, f _N = −20.5, f = −36.5, m = 4.0, d0 = −28.0 r d n ν r1 = −34.0 d1 = 2.0 n1 = 1.8052 ν1 = 25.3 r2 = −17.8 d2 = 1.0 n2 = 1.5145 ν2 = 54.5 r3 = 25.9 d3 = 108.0 n _P / n _N = n1 /N2=1.19, ν _N / ν _P = ν 2 / ν 1 = 2.15 (n _N × ν _N × f _N ) / (n _P × ν _P × f _P ) = 0.84 One of the above Tables 1 to 6 If one is the first lens group G ₁ in the magnifying lens and the other one is the second lens group G _{2 in} the magnifying lens, an arbitrary magnifying power can be set. The magnifications of the lens groups shown in Tables 1 to 3 are all 2.5 times, and the magnifications of the lens groups shown in Tables 4 to 6 are all 4.0 times. Therefore, for example, 1 in Table 1 to Table 3
Is the first lens group G _{1 in} the magnifying lens, and Tables 4 to 6
If one of them is the second lens group G _{2 in} the magnifying lens,
Magnification of the entire magnifying lens is 10 times (2.5 times x 4.0 times)
Becomes Further, if any two in Tables 1 to 3 are the first lens group G ₁ and the second lens group G ₂ , the magnification of the entire magnifying lens is 6.25 times (2.5 times × 2. 5 times). In addition, any two of Tables 4 to 6 are first
With the lens group G ₁ and the second lens group G ₂ , the magnification of the entire magnifying lens is 16 times (4.0 times × 4.0 times).
Furthermore, the first and second lens groups may be the same lens, which is advantageous for cost reduction.

Although it is possible to construct the magnifying lens with only one group, a sufficient magnifying power cannot be obtained.
Next, aberration diagrams of the lens groups listed in Tables 1 to 6 are shown in FIGS. 5, 6, 7, 8, 9, and 10, respectively. In each aberration diagram, the distance between the exit pupil position of the objective lens 6 shown in FIG. 1 and the image I ₀ formed by the objective lens 6 is 160, and when the light source is arranged at this exit pupil position. Is shown.

As shown in the aberration diagrams of FIGS.
It is understood that each lens group forming the magnifying lens has an extremely good image forming performance even if the lens group has an extremely small number of lenses such as two lenses. In the above embodiments, the example in which the magnifying lens 7 is arranged on the image side of the objective lens 6 has been shown, but the present invention is not limited to this. For example, as shown in FIG. 4, even if the magnifying lens 7 is arranged on the image side of the relay system 11 that re-images the image I ₀ formed by the objective lens 6, that is, in the convergent light flux formed by the relay system 11. good.
In this case, the objective lens 6 and the relay system 11 function as an objective optical system that converts the light flux from the observed object into a convergent light flux.

[0024]

As described above, according to the present invention, it is possible to achieve a high-performance magnifying lens which is compact and has a large magnifying power, although it has an extremely simple structure. Moreover, there is an advantage that the present invention can be applied to the conventional microscope with almost no improvement.

Further, if the magnifying lens is composed of a plurality of lens groups, it is possible to obtain a large magnifying power while achieving a more compact size than ever before. Further, by arbitrarily combining a plurality of lens groups having different magnifications, there is an advantage that the magnification of the magnifying lens can be set arbitrarily. In addition, since each lens group constituting the magnifying lens of the present invention can be realized with an extremely small number of lens components, such as two in principle, it is expected that the size and cost will be greatly reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram when a magnifying lens of the present invention is incorporated in a microscope.

FIG. 2 is a diagram showing a cross-sectional configuration of a magnifying lens incorporated in FIG.

FIG. 3 is a diagram for explaining the principle of the present invention.

FIG. 4 is a diagram showing a modification of the embodiment shown in FIG.

FIG. 5 is a diagram showing various aberrations of the lens group having a magnification of 2.5 times shown in Table 1.

FIG. 6 is a diagram showing various aberrations of the lens group having a magnification of 2.5 times shown in Table 2.

FIG. 7 is a diagram showing various aberrations of the lens group having a magnification of 2.5 times shown in Table 3.

FIG. 8 is a diagram of various types of aberration of a lens unit having a magnification of 4.0 times shown in Table 4.

9 is a graph showing various aberrations of the lens unit having a magnification of 4.0 times shown in Table 5. FIG.

FIG. 10 is a diagram of various types of aberration of a lens unit having a magnification of 4.0 times shown in Table 6.

FIG. 11 is a diagram showing a schematic configuration of a conventional microscope.

12 is a diagram showing an example in which the magnification of the microscope shown in FIG. 11 is further increased.

[Explanation of symbols for main parts]

5 ・ ・ ・ ・ ・ ・ Sample 6 ・ ・ ・ ・ ・ ・ ・ ・ Objective lens 7 ・ ・ ・ ・ ・ ・ ・ Magnifying lens 11 ・ ・ ・ ・ ・ ・ ・ Relay system G ₁・..... 1st lens group G ₂ ..... 2nd lens group

Claims (4)

[Claims] 1. A magnifying lens for converting a light beam from an object to be observed into a convergent light beam, and enlarging a magnification of an objective optical system for a microscope forming a spatial image of the object to be observed to a predetermined magnification, wherein the magnifying lens is A plurality of lens groups having negative refracting powers that are independently aberration-corrected, and by arranging the plurality of lens groups in a convergent light beam formed by the objective optical system for a microscope, the aerial image can be formed in a predetermined manner. A magnifying lens for microscopes, which converts to magnification. 2. The magnifying lens for a microscope according to claim 1, wherein each of the lens groups includes a positive lens and a negative lens. 3. The positive lens has a concave surface facing the object side.
The negative lens is a biconcave lens, and the positive lens in each lens group has a refractive index of n._PAnd the above
The Abbe number of the positive lens in each lens group is ν_P, Each of the above
The focal length of the positive lens in the lens group is f_P, In each lens
The refractive index of the negative lens is n_N, Negative lens in each lens group
Abbe number of ν _N, The focus of the negative lens in each lens group
Distance f_NThen, (1) 1.1 <n_P/ N_N<1.4 (2) 2.0 <ν_N/ Ν_P<3.5 (3) −0.95 <(n_N× ν_NXf_N) / (N_P× ν_P
Xf_P) <-0.8 is satisfied, The microscope according to claim 1 or 2, characterized in that
Magnifying lens for mirror. 4. The magnifying lens for a microscope according to claim 2, wherein the positive lens and the negative lens are cemented to each other.