JPH0756087A - Zoom tube lens for infinity correction type zoom microscope - Google Patents

Abstract

PURPOSE:To embody the zoom tube lens for infinity correction type zoom microscope, which has a high zoom ratio reaching 10 and can obtain a high object magnification, with a low cost. CONSTITUTION:This mechanical compensation type zoom lens consists of four groups having positive, negative, negative, and positive refracting powers in order from the object side, and the first group has the positive refracting power and is fixed during zooming, and the second group has the negative refracting power and is linearly moved during zooming to act as the main body for power varying, and the third group has the negative refracting power and is linearly moved during zooming to fixedly keep the image position, and the fourth group has the positive refracting power and is fixed during zooming, and its first group consists of a positive single lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a tube lens used in an infinity correction type microscope as a zoom lens, and particularly has a high zoom ratio reaching a zoom ratio of 10 and a high zoom ratio when used in a microscope. The present invention relates to a zoom tube lens capable of obtaining an object magnification.

[0002]

2. Description of the Related Art In an infinity correction type microscope, the ratio of the focal lengths of the tube lens and the objective lens is the magnification.
Utilizing this property, it has been conventionally performed to change the magnification by using a tube lens as a zoom lens. Conventionally, a zoom tube lens of a large-diameter high-magnification zoom microscope of infinity correction type by the same inventor of the present invention (Japanese Patent Application No. 4-19926 by the same applicant as the present applicant).
Disclosed in the specification of No. 6 patent application. However, it has not been published at the time of this application. ), But the first group required as many as three lenses.

[0003]

Therefore, the conventional zoom tube lens for an infinity correction type zoom microscope has a problem that the cost is high because the number of constituent lenses is large. The present invention was created in view of the problems of the prior art as described above, and provides a zoom tube lens for an infinity-correction type zoom microscope in which the first lens group of the zoom tube lens is composed of only one lens. The purpose is to do.

[0004]

SUMMARY OF THE INVENTION The present invention is a zoom lens used as a tube lens of an infinity correction type microscope, and the zoom lens is a mechanical system composed of four groups of positive, negative, negative and positive refracting powers from the object side. Compensation type, the first group has a positive refracting power, is fixed during zooming, the second group has a negative refracting power, moves linearly during zooming, and has a zooming effect. It has a main power, the third group has a negative refracting power, moves non-linearly during zooming to keep the image position constant, and the fourth group has a positive refracting power and has a positive refracting power during zooming. The first group, which is fixed, is characterized by a zoom tube lens for an infinity correction type zoom microscope, which is composed of a positive single lens.

[0005]

In general, the zoom lens is apt to have the largest aberration at the telephoto end where the light beam incident height is maximum. The first group is most important for correcting aberrations at the telephoto end. On the other hand, in the infinity correction type zoom microscope obtained according to the present invention, since the NA of the objective lens becomes maximum at the telephoto end, the incident height of light rays on the zoom tube lens also becomes maximum. Aberration correction at the edge is of utmost importance.

However, as a result of repeated design and examination by the inventor of the present invention, it has been found that in the case of a zoom tube lens for an infinity-correction type zoom microscope, the situation regarding the first group is different from that of a general zoom lens. . That is, the first
Since the objective lens is placed adjacent to the group, it is usually the first
Aberration correction that should be borne by the group can be passed on to the objective lens. This makes it possible to reduce the burden of aberration correction on the first group.

For the above reasons, it has become possible to use a single lens as the lens structure of the first group.

Regarding the glass type, as shown in Example 9 using the fluorite type glass type for the first group and Example 10 using the SF type having a large dispersion among the SF type for the first group, All the glass types currently on the market can be used for one group.

As for the lens construction of each of the second to fourth groups, it is not necessary to make the construction constant, as shown in the embodiments.

The objective lens combined with the present invention is
The first group of zoom tube lenses must compensate for the insufficient aberration correction due to the single lens.
For example, when the object magnification at the telephoto end is set to about 50 times, it is divided into three components, and has a positive-refractive-force first component composed of two positive single lenses in order from the object side, and three or more positive lens groups. It consists of the second component of positive refracting power and the third component of negative refracting power consisting of the first group of cemented lenses. The smaller Abbe number of the positive single lens of the first component is ν _S , and only the positive lens of the second component is When the average value of the Abbe number is ν _A and the Abbe number of the third component positive lens is ν _L , (1) 32 <ν _S <57 (2) 68 <ν _A <95.2 (3) 20 < High N for infinity corrected zoom microscope with condition of ν _L <38
A, it is desirable to use a high magnification objective lens.

As can be seen from the examples, the zoom tube lens of the present invention is effectively used not only in the high magnification range but also in the medium magnification range infinity correction type zoom microscope.

[0012]

EXAMPLES Since this zoom tube lens for a zoom microscope is used in combination with an objective lens, the objective lens will be disclosed in each of the examples and will be described in a form including it.

Example 1 FIG. 1 shows a lens configuration diagram of Example 1. Symbols in the figure, r ₁ . ． ． r ₃₄ is the radius of curvature of each lens, d ₁ .. ． ． d ₃₃ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0014]

[Table 1]

Here, n ₁ .. ． _. N ₂₀ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₂₀ is the Abbe number for the d-line. The wide end (5 times), the middle (21
8), various aberrations at the tele end (50 times) are shown in FIGS. 8, 9 and 10, respectively.

Example 2 FIG. 2 shows a lens configuration diagram of Example 2. Symbols in the figure, r ₁ . ． ． r ₂₈ is the radius of curvature of each lens, d ₁ .. ． ． d ₂₇ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0017]

[Table 2]

Here, n ₁ .. ． _. N ₁₆ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₁₆ is the Abbe number for the d-line. Aberrations at the wide end (1.5 times), the middle (6.2 times), and the tele end (15 times) in this example are shown in FIGS. 11, 12, and 13, respectively.

(Embodiment 3) FIG. 3 is a lens configuration diagram of the third embodiment. Symbols in the figure, r ₁ . ． ． r ₂₆ is the radius of curvature of each lens, d ₁ . ． ． d ₂₅ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0020]

[Table 3]

Here, n ₁ .. ． _. N ₁₅ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₁₅ is the Abbe number for the d-line. Various aberrations at the wide end (1.5 times), the middle (6.2 times), and the tele end (15 times) in this example are shown in FIGS. 14, 15, and 16, respectively.

Example 4 FIG. 4 shows a lens configuration diagram of Example 4. Symbols in the figure, r ₁ . ． ． r ₃₈ is the radius of curvature of each lens, d ₁ .. ． ． d ₃₇ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0023]

[Table 4]

Here, n ₁ .. ． _. N ₂₂ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₂₂ is the Abbe number for the d-line. In this example, the number of fields of view is 18. Aberrations at the wide end (5 times), the middle (21 times), and the tele end (50 times) in this example are shown in FIGS.
Shown as FIG.

(Embodiment 5) FIG. 5 shows a lens configuration diagram of Embodiment 5. Symbols in the figure, r ₁ . ． ． r ₂₆ is the radius of curvature of each lens, d ₁ . ． ． d ₂₅ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0026]

[Table 5]

Here, n ₁ .. ． _. N ₁₅ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₁₅ is the Abbe number for the d-line. Aberrations at the wide end (0.9 times), the middle (3.7 times), and the tele end (9 times) in this example are shown in FIGS. 20, 21, and 22, respectively.

(Embodiment 6) In this embodiment, the structure of the lens is the same as that of the embodiment 2, so that it is not shown. The specifications of the optical system in this example are as shown in the following table.

[0029]

[Table 6]

Here, n ₁ . ． _. N ₁₆ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₁₆ is the Abbe number for the d-line. Aberrations at the wide end (1.5 times), the middle (6.2 times), and the tele end (15 times) in this example are shown in FIGS. 23, 24, and 25, respectively.

(Embodiment 7) FIG. 6 shows a lens configuration diagram of Embodiment 7. Symbols in the figure, r ₁ . ． ． r ₂₉ is the radius of curvature of each lens, d ₁ .. ． ． d ₂₈ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0032]

[Table 7]

Here, n ₁ .. ． _. N ₁₇ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₁₇ is the Abbe number for the d-line. Aberrations at the wide end (12.5 times), the middle (28 times), and the tele end (50 times) in this example are shown in FIGS. 26, 27, and 28, respectively.

(Embodiment 8) FIG. 7 shows the lens construction of the eighth embodiment. Symbols in the figure, r ₁ . ． ． r ₂₁ is the radius of curvature of each lens, d ₁ .. ． ． d ₂₀ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0035]

[Table 8]

Here, n ₁ .. ． _. N ₁₂ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₁₂ is the Abbe number for the d-line. Aberrations at the wide end (3.75 times), the middle (8.3 times), and the tele end (15 times) in this example are shown in FIGS. 29, 30, and 31, respectively.

(Embodiment 9) In this embodiment, the structure of the lens is the same as in the case of the above-mentioned Embodiment 4, so that it is not particularly shown. The specifications of the optical system in this example are as shown in the following table.

[0038]

[Table 9]

Here, n ₁ .. ． _. N ₂₂ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₂₂ is the Abbe number for the d-line. In this example, the number of fields of view is 18.
In this example, the first group of zoom tube lenses uses a fluorite-based glass species.
The group proves that all the glass types currently on the market can be used. Various aberrations at the wide end (5 times), the middle (21 times), and the tele end (50 times) in this example are shown in FIGS. 32, 33, and 34, respectively.

(Embodiment 10) In this embodiment, the structure of the lens is the same as in the case of the above-mentioned Embodiment 4, so that it is not shown. The specifications of the optical system in this example are as shown in the following table.

[0041]

[Table 10]

Here, n ₁ .. ． _. N ₂₂ is the refractive index at the d-line of each lens, [nu _1. ． ． ν ₂₂ is the Abbe number for the d-line. In this example, the number of fields of view is 18.
In this embodiment, the first group of the zoom tube lens uses a glass type having a large dispersion in the SF system, and together with the ninth example, all the commercially available glass types can be used for the first group. Prove that. Aberrations at the wide end (5 times), the middle (21 times), and the tele end (50 times) in this example are shown in FIGS. 35, 36, and 37, respectively.

[0043]

When the zoom tube lens of the present invention having the above-mentioned structure is used in a zoom microscope, the high object magnification, high NA, long working distance, and high zoom ratio can be achieved with a smaller number of lenses than the conventional zoom microscope. Can be achieved with. That is, according to the present invention, the configuration of the first group having the largest lens diameter in the zoom tube lenses is one in comparison with the conventional three lenses, which is advantageous in cost reduction.

As is clear from the first embodiment, there is an effect that a zoom microscope with a zoom ratio of 10 can be obtained in which the object magnification can be continuously varied with one objective lens from 5 times to 50 times.

[Brief description of drawings]

FIG. 1 is a lens configuration diagram of a first embodiment of the present invention.

FIG. 2 is a lens configuration diagram of a second embodiment of the present invention.

FIG. 3 is a lens configuration diagram of a third embodiment of the present invention.

FIG. 4 is a lens configuration diagram of a fourth embodiment of the present invention.

FIG. 5 is a lens configuration diagram of a fifth embodiment of the present invention.

FIG. 6 is a lens configuration diagram of a seventh embodiment of the present invention.

FIG. 7 is a lens configuration diagram of an eighth embodiment of the present invention.

FIG. 8 is a diagram of various types of aberration at the wide end according to the first example of the present invention.

FIG. 9 is a diagram showing various aberrations in the middle of the above.

FIG. 10 is a diagram showing various aberrations at the telephoto end.

FIG. 11 is a diagram of various types of aberration at the wide end according to the second example of the present invention.

FIG. 12 is a diagram showing various aberrations in the middle of the above.

FIG. 13 is a diagram showing various aberrations at the telephoto end.

FIG. 14 is a diagram of various types of aberration at the wide end according to the third example of the present invention.

FIG. 15 is a diagram showing various aberrations in the middle of the above.

FIG. 16 is a diagram showing various aberrations at the telephoto end.

FIG. 17 is a diagram of various types of aberration at the wide end according to the fourth example of the present invention.

FIG. 18 is a diagram showing various aberrations in the middle of the above.

FIG. 19 is a diagram showing various aberrations at the telephoto end.

FIG. 20 is a diagram of various types of aberration at the wide end according to the fifth example of the present invention.

FIG. 21 is a diagram showing various aberrations in the middle of the above.

FIG. 22 is a diagram showing various aberrations at the telephoto end.

FIG. 23 is a diagram of various types of aberration at the wide end according to the sixth example of the present invention.

FIG. 24 is a diagram of various types of aberration in the middle of the above.

FIG. 25 is a diagram showing various aberrations at the telephoto end.

FIG. 26 is a diagram of various types of aberration at the wide end according to the seventh example of the present invention.

FIG. 27 is a diagram showing various aberrations in the middle of the above.

FIG. 28 is a diagram showing various aberrations at the telephoto end.

FIG. 29 is a diagram of various types of aberration at the wide end according to Example 8 of the present invention.

FIG. 30 is a diagram of various types of aberration in the middle of the above.

FIG. 31 is a diagram showing various aberrations at the telephoto end.

FIG. 32 is a diagram of various types of aberration at the wide end according to the ninth example of the present invention.

FIG. 33 is a diagram showing various aberrations in the middle of the above.

FIG. 34 is a diagram showing various aberrations at the telephoto end.

FIG. 35 is a diagram of various types of aberration at the wide end according to the tenth example of the present invention.

FIG. 36 is a diagram showing various aberrations in the middle of the above.

FIG. 37 is a diagram showing various aberrations at the telephoto end.

Claims (1)

[Claims] 1. A zoom lens used as a tube lens of an infinity correction type microscope, the zoom lens being a mechanical compensation type consisting of four groups of positive, negative, negative and positive refracting powers from the object side, The first group has a positive refracting power and is fixed during zooming, the second group has a negative refracting power, and moves linearly during zooming to form the main force of zooming, and the third group Has a negative refracting power, moves non-linearly during zooming to keep the image position constant, the fourth group has a positive refracting power and is fixed during zooming, and the first group Is a zoom tube lens for infinity-corrected zoom microscopes, which consists of a positive single lens.