JPH0784189A - Objective lens for infinity-corrective zoom microscope - Google Patents

Abstract

PURPOSE:To provide an objective lens of an infinity-corrective zoom microscope having a large NA(numerical aperture), a high objective magnification and a long working distance. CONSTITUTION:This lens is divided into three components, in order from the object side, a first component of positive refractive power composed of two single positive lenses, a second component of a positive refractive power comprising three and more positive lenses and a third component composed of a joined lens group, by representing the smaller Abbe number of the single positive lenses of the first component among the lenses by nuS, the average value of the Abbe number of only the positive lens of the second component by nuA and the Abbe number of the positive ens of the third component by nuL, the following conditions hold. (1) 32<nuS<57, (2) 68<nuA<95, (3) 20<nuL<38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an infinity correction type high N
A. The present invention relates to an objective lens which is a high-magnification objective lens and is used in an infinity correction type zoom microscope using a tube lens as a zoom lens.

[0002]

2. Description of the Related Art A high N, which has been conventionally used in zoom microscopes.
There was an objective lens of A. However, they merely diverted a general microscope objective lens.

[0003]

A zoom microscope using a general microscope objective lens has a small zoom ratio of about 2 to 3, and the NA of the objective lens does not increase even when zooming up. There was a problem that NA suitable for the object magnification could not be obtained.

The present invention was created in view of the problems of the prior art as described above, can be used at a high zoom ratio, and always has an infinity correction type zoom microscope which secures an NA suitable for the object magnification. To provide an objective lens with high NA and high object magnification.

[0005]

The present invention is divided into three components, a first component of positive refracting power composed of two positive single lenses in order from the object side, and a positive refracting power having three or more positive lenses. Of the first component positive single lens, the smaller Abbe number of the first component is ν _S , and the average Abbe number of the second component positive lens only is ν _S.
Assuming that _A and the Abbe number of the positive lens of the third component are ν _L , (1) 32 <ν _S <57 (2) 68 <ν _A <95.6 (3) 20 <ν _L <38 The objective lens for the infinity-corrected zoom microscope has a feature.

The objective lens of the present invention is a so-called infinity correction type objective lens and is used in an infinity correction type zoom microscope using a tube lens as a zoom lens.

[0007]

The objective lens of the present invention achieves apochromat correction by intentionally generating chromatic aberration in the first component and canceling it out in the subsequent second component. This method is conventionally known to be advantageous for apochromat correction of a high-power objective lens. Further, the third component has a great influence on correction of chromatic aberration of magnification.

Regarding condition (1): This condition defines the smaller value ν _S of the Abbe numbers of the two positive single lenses of the first component. When ν _S is smaller than the right side of conditional expression (1), the above effect begins to appear, but when it is larger than the left side, chromatic aberration cannot be completely corrected by the second component, so chromatic aberration of magnification and spherical aberration of color deteriorate, and apochromat correction is performed. Is impossible. Example 6 is an example in which the Abbe number ν _S of the lens on the object side of the first component is set to a value close to the left side, and Example 8 is the Abbe number ν _S of the lens on the object side of the first component close to the right side. It is an example in which the value is set. Example 7 is an example in which the Abbe number ν _S of the lens on the image side of the first component is set to a value close to the left side. In both cases, the aberration of the third wavelength (C line) is worse.

Regarding condition (2): This condition defines the average value ν _A of the Abbe number of the positive lens in the second component, which plays a central role in apochromat correction. If ν _{A is set} to the right side or more, the chromatic aberration caused by the condition (1) can be corrected and the apochromat correction can be performed. Best results are obtained when ν _A is the left side. Example 11
Indicates that ν _A is a value close to the left side, and the aberration is bad. On the other hand, in Example 9, ν _A is set to a value close to the right side, and the apochromat correction is sufficiently performed.

Regarding condition (3): This condition defines the Abbe number ν _L of the positive lens of the third component. The use of such a glass type having a large chromatic dispersion serves to enhance the ability to correct lateral chromatic aberration. The effect begins to appear when ν _L becomes smaller than the right side. The left side is the limit of the Abbe number of the currently marketed glass types. Example 10 is ν _L
Is a value close to the right side, and the apochromat correction is deteriorated along with the chromatic aberration of magnification. Example 11 is ν
_L is a value close to the left side.

[0011]

Embodiments Since this objective lens is used in combination with a zoom tube lens, each embodiment is shown including the zoom tube lens. (Embodiment 1) FIG. 1 shows a lens configuration diagram of Embodiment 1.
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.

[0012]

[Table 1]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 95.0 + 81.6 + 70.2) / 4 = 8
2.1 Condition (3) ν _L = ν ₁₀ = 25.4 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. It shows in FIG.

(Embodiment 2) FIG. 2 shows a lens configuration diagram of Embodiment 2. 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.

[0015]

[Table 2]

Here, n ₁ .. ． ． n ₂₀ is the refractive index of each lens for the d-line, ν ₁ . ． ． ν ₂₀ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ ) / 3 = (95.
0 + 95.0 + 81.6) /3=90.5 Condition (3) ν _L = ν ₉ = 25.4 Various values at the wide end (5 times), the middle (21 times), and the tele end (50 times) in this embodiment. Aberrations are shown in FIGS. 8, 9 and 10, respectively.

(Third Embodiment) FIG. 3 shows a lens configuration diagram of the third embodiment. 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.

[0018]

[Table 3]

Here, n ₁ . ． ． n ₁₇ is the refractive index of each lens for the d-line, ν ₁ . ． ． ν ₁₇ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ ) / 3 = (95.
0 + 95.0 + 81.6) /3=90.5 Condition (3) ν _L = ν ₉ = 25.4 Wide end (12.5 times), intermediate (28)
1) and various aberrations at the tele end (50x)
1, FIG. 12 and FIG.

(Embodiment 4) FIG. 1 shows a lens configuration diagram of Embodiment 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.

[0021]

[Table 4]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 81.6 + 81.6 + 70.2) / 4 = 7
8.8 Condition (3) ν _L = ν ₁₀ = 25.4 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.
5, shown in FIG.

(Embodiment 5) FIG. 1 shows a lens configuration diagram of Embodiment 5. 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.

[0024]

[Table 5]

Here, n ₁ .. ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(95.0 + 95.0 + 95.0 + 95.0) / 4 = 9
5.0 Condition (3) ν _L = ν ₁₀ = 25.4 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.
8, shown in FIG.

Examples 6 to 11 are close to the lower limit or upper limit of the conditions. At this time, the aberration is most deteriorated at the tele end, and the deterioration at the wide end and the middle is relatively small. Therefore, the aberration diagram shows only the tele end.

(Sixth Embodiment) FIG. 1 shows a lens configuration diagram of the sixth embodiment. 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.

[0028]

[Table 6]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 32.3 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 81.6 + 70.2 + 70.2) / 4 = 7
5.9 Condition (3) ν _L = ν ₁₀ = 25.4 In this example, ν ₁ is ν _S, which is a value close to the left side of condition (1). The tele end (5
20 shows various aberrations at 0 times.

(Embodiment 7) FIG. 1 shows a lens configuration diagram of Embodiment 7. 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.

[0031]

[Table 7]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₂ = 33.8 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 95.0 + 81.6 + 70.2) / 4 = 8
2.1 Condition (3) ν _L = ν ₁₀ = 25.4 In this example, ν ₂ is ν _S, which is close to the left side of condition (1). The tele end (5
Various aberrations at 0 times) are shown in FIG.

(Embodiment 8) FIG. 1 shows a lens configuration diagram of Embodiment 8. 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.

[0034]

[Table 8]

Here, n ₁ .. ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 56.5 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 95.0 + 81.6 + 70.2) / 4 = 8
2.1 Condition (3) ν _L = ν ₁₀ = 23.9 In this example, ν ₁ is ν _S, which is a value close to the right side of condition (1). The tele end (5
FIG. 22 shows various aberrations at 0 times.

(Embodiment 9) FIG. 1 shows a lens configuration diagram of Embodiment 9. 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.

[0037]

[Table 9]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(95.0 + 95.0 + 95.0 + 95.0) / 4 = 9
5.0 Condition (3) ν _L = ν ₁₀ = 25.4 In this example, ν _A is close to the right side of condition (2). FIG. 23 shows various aberrations at the telephoto end (50 times) in this example.

(Embodiment 10) FIG. 1 shows a lens configuration diagram of Embodiment 10. 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.

[0040]

[Table 10]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 35.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 95.0 + 81.6 + 70.2) / 4 = 8
2.1 Condition (3) ν _L = ν ₁₀ = 37.2 In this example, ν _L is a value close to the right side of condition (3). FIG. 24 shows various aberrations at the telephoto end (50 times) in this example.

(Embodiment 11) FIG. 1 shows a lens configuration diagram of Embodiment 11. 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.

[0043]

[Table 11]

Here, n ₁ . ． ． n ₂₂ is the refractive index of each lens with respect to the d-line, ν ₁ . ． ． ν ₂₂ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 41.0 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(81.6 + 70.2 + 70.2 + 52.4) / 4 = 6
8.6 Condition (3) ν _L = ν ₁₀ = 20.9 In this example, ν _A is close to the left side of condition (2), and ν _L is on the left side of condition (3). It is a close number. FIG. 25 shows various aberrations at the telephoto end (50 times) in this example.

(Embodiment 12) FIG. 4 shows a lens configuration diagram of Embodiment 12. Symbols in the figure, r ₁ . ． ． r ₄₁ is the radius of curvature of each lens, d ₁ .. ． ． d ₄₀ represents the thickness or spacing of each lens. The specifications of the optical system in this example are as shown in the following table.

[0046]

[Table 12]

Here, n ₁ . ． ． n ₂₅ is the refractive index of each lens for d-line, ν ₁ . ． ． ν ₂₅ is the Abbe number for the d-line of each lens. In this embodiment, the following conditions are satisfied. Condition (1) ν _S = ν ₁ = 40.9 Condition (2) ν _A = (ν ₄ + ν ₆ + ν ₇ + ν ₉ ) / 4 =
(95.0 + 95.0 + 95.0 + 95.0) / 4 = 9
5.0 Condition (3) ν _L = ν ₁₀ = 25.4 In this example, the number of fields of view is 24. In this embodiment, the wide end (10 times), the middle (29 times), the tele end (6
0x) various aberrations in FIGS. 26, 27 and 2 respectively.
8 shows.

[0048]

According to the present invention, it is possible to use at a high zoom ratio, and a high NA, a high object magnification, and a long operation for an infinity correction type zoom microscope which always secures an NA suitable for the object magnification. An objective lens having a distance can be realized.

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 varied from 5 times (NA0.1) to 50 times (NA0.5). .

[Brief description of drawings]

FIG. 1 is a lens configuration diagram of Example 1 and Examples 4 to 11 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 twelfth embodiment of the present invention.

FIG. 5 is a diagram of various types of aberration at the wide end according to the first example of the present invention.

FIG. 6 is a diagram showing various aberrations in the middle of the above.

FIG. 7 is a diagram showing various aberrations at the telephoto end.

FIG. 8 is a diagram of various types of aberration at the wide end according to the second 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 Example 3 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 fourth 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 fifth 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 telephoto end according to the sixth embodiment of the present invention.

FIG. 21 is a diagram of various types of aberration at the telephoto end according to the seventh embodiment of the present invention.

FIG. 22 is a diagram of various types of aberration at the telephoto end according to the eighth embodiment of the present invention.

FIG. 23 is a diagram of various types of aberration at the telephoto end according to the ninth embodiment of the present invention.

FIG. 24 is a diagram of various types of aberration at the tele end of Embodiment 10 of the present invention.

FIG. 25 is a diagram of various types of aberration at the tele end of Embodiment 11 of the present invention.

FIG. 26 is a diagram of various types of aberration at the wide end according to Example 12 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.

[Explanation of symbols]

r ₁ . ． ． r ₃₈ Radius of curvature of each lens d ₁ .. ． ． d ₃₇ Thickness or spacing of each lens

Claims (1)

[Claims] 1. A first component having a positive refracting power composed of two positive single lenses in order from the object side, a second component having a positive refracting power having three or more positive lenses, and a cemented lens 1.
The third component is composed of a third component, and the smaller Abbe number of the positive single lens of the first component is ν _S, the average Abbe number of only the positive lens of the second component is ν _A , and the Abbe number of the positive lens of the third component is An objective for an infinity-corrected zoom microscope having a condition that (1) 32 <ν _S <57 (2) 68 <ν _A <95.6 (3) 20 <ν _L <38, where Abbe number is ν _L lens.