JPH11316339A - Objective optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an objective optical system whose entire length is short and whose lens outside diameter is small through it can realize enlarging observation by moving a 2nd group on an optical axis so that variable power action may be performed and making it satisfy specified conditions. SOLUTION: This optical system is constituted of a 1st group G1 having positive refractive power, a 2nd group G2 having negative refractive power and a 3rd group G3 having positive refractive power in order from an object side. By moving the 2nd group G2 on the optical axis, the variable power action is performed, and the system satisfies the conditional expressions: 0.1<|1/ f2 (DW-DT)}|<2, 1<|(fW.fT)<1/2> /f1 |<2. Provided that f1 and f2 are the focal distances of the 1st and the 2nd groups G1 and G2, DW and DT are intervals between the 1st and the 2nd groups G1 and G2 at a wide angle end and a telephoto end, fW and fT are the focal distances of the entire system at the wide angle end and the telephoto end, respectively. Thus, the occurrence of aberration in the 2nd group G2 is restrained and the aberration is kept excellent, and the refractive power of the 2nd group G2 is made strong while keeping the aberration excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective optical system having a zoom function.

[0002]

2. Description of the Related Art In recent years, it has been required to perform magnified observation in addition to ordinary observation in order to perform precise diagnosis of a lesion or the like in an endoscope. Further, in the endoscope, it is required to shorten the length of the rigid portion at the distal end and to reduce the outer diameter. Therefore, the optical system for magnifying observation is strongly required to reduce the overall length and the lens outer diameter.

[0003] In the field of video cameras and digital cameras, it is desired not only to perform magnifying observation but also to reduce the overall length and diameter of the lens system.

As a conventional example of a magnifying observation optical system, Japanese Patent Publication No. Sho 6
Optical systems described in JP-A-1-44283, JP-A-4-218012, and JP-A-6-317744 are known. These conventional examples include, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, and a third group having a positive refractive power, and the second group moves on the optical axis. This is a lens system that performs a zooming action.

[0005]

In each of these conventional examples, since the moving distance of the second lens unit during zooming is long, the entire length of the lens system is long, and the divergent light flux from the second lens unit having a negative refractive power. Has the disadvantage that the beam height is significantly higher in the third group than in the other groups, so that the outer diameter of the third group becomes large.

An object of the present invention is to provide an objective optical system which has a short overall length and a small lens outer diameter while being capable of magnifying observation.

[0007]

The objective optical system according to the present invention comprises:
In order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power are provided. The second lens unit moves on the optical axis to change the magnification. And the following conditions (1) and (2) are satisfied. (1) 0.1 <| 1 / {f ₂ (D _W −D _T )} | <2 (2) 1 <| (f _W · f _T ) ^1/2 / f ₁ | <2 where f ₁ , F ₂ are the focal lengths of the first and second lens units, respectively, and D _W and D _T are the first and second lens units at the wide-angle end and the telephoto end, respectively.
Group and spacing of the second group, f _W, is f _T is a focal length of the entire system at each wide angle end and the telephoto end.

In general, in order to shorten the entire length of the optical system, it is effective to increase the refractive power of each group and shorten the interval. In the optical system according to the present invention including the first positive lens unit, the second negative lens unit, and the third positive lens unit in order from the object side, the refractive power of each lens unit is increased to shorten the entire length of the optical system. It is desirable. In particular, it is effective to shorten the total length of the optical system by reducing the amount of movement of the second unit during zooming by increasing the refractive power of the second unit having a zooming action. However, when the refractive power of the second lens unit is extremely increased, aberrations generated in this lens unit become large, and it is difficult to obtain good imaging performance.

According to the present invention, the condition (1) is satisfied to suppress the occurrence of aberrations in the second lens unit so as to maintain the aberrations favorably. It has been made possible to increase the refractive power, thereby reducing the overall length of the optical system.

If the lower limit of 0.1 of condition (1) is exceeded, the second condition
The refracting power of the group becomes weak, the amount of movement of the second group becomes large, and the total length of the optical system becomes long. When the value exceeds the upper limit of 2 of the condition (1), the Petzval sum of the aberrations generated in the second lens group, in particular, the generation amount of which contributes to the refracting power becomes large, and the image plane falls in a direction away from the object side.

Instead of the condition (1), the following condition (1-
It is even more preferable that the condition (1) is satisfied. (1-1) 0.15 <| 1 / {f ₂ (D _W −D _T )} | <1

Also, as in the present invention, the positive first lens unit and the negative second lens unit
In an optical system composed of a group and a positive third group, in order to shorten the overall length of the optical system, it is effective to increase the refractive power of the first group in addition to the second group. However, when the refracting power of the first lens group whose on-axis and off-axis incident light heights are significantly different between the wide-angle end and the telephoto end is extremely increased, the amount of coma aberration is particularly large at the wide-angle end where the off-axis light height is high. become. In addition, at the telephoto end where the on-axis ray height is high, the amount of generated spherical aberration is particularly large, and it is difficult to correct these aberrations.

The present invention satisfies the condition (2) in order to increase the refracting power of the first lens unit and reduce the overall length of the optical system while suppressing the occurrence of aberrations at the wide-angle end and the telephoto end.

If the lower limit of 1 to condition (2) is exceeded, the refractive power of the first lens unit will be weak, and the total length of the optical system cannot be reduced. When the value exceeds the upper limit of 2 of the condition (2), the aberration generated in the first lens unit becomes large, and it becomes difficult to correct the aberration.

In the objective optical system of the present invention, it is desirable that the following condition (2-1) is satisfied instead of the condition (2). (2-1) 1.1 <| (f _W · f _T ) ^1/2 / f ₁ | <1.8

The objective optical system according to the present invention comprises a plurality of groups and an aperture stop, and at least one of the plurality of groups moves on the optical axis to have a zooming function. If any one of the groups (not a specific group) satisfies the following condition (3) and has a small outer diameter, the diameter can be reduced without significantly deteriorating the peripheral light amount. . (3) 0 <H _u / H _s <0.8 where _Hu is the actual ray height of the off-axis upper ray at the aperture stop position, and H _s is the radius of the aperture stop.

In particular, if the optical system is composed of, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, particularly at the wide end, In the third group having a positive refractive power, into which the divergent light beam from the second group having a negative refractive power having a zooming effect is incident, the height of the off-axis ray is increased. For this reason, the outside diameter of the lens of the third group becomes large, which hinders a reduction in the diameter of the lens system. In order to reduce the diameter of the lens system, it is desirable to reduce the outer diameter of the third lens unit. However, if the outer diameter of the third lens unit is simply reduced, the peripheral light beam is blocked, the amount of peripheral light is reduced, and the peripheral portion of the image becomes significantly darker than the central portion.

However, in the case of the endoscope objective optical system, since the angle of view is wide and the amount of generation of negative distortion is as large as about 30% or more, the imaging magnification at the peripheral portion is smaller than that at the central portion. When the angle of view is wide, the distortion may be 40% or more. Therefore, in the case of the endoscope optical system,
The amount of light collected on the outer peripheral portion is larger than that on the central portion.

By utilizing such a feature, it is possible to reduce the outer diameter of the third lens unit to such an extent that the peripheral portion of the image does not become extremely dark.

In consideration of the above points, the optical system of the present invention must satisfy the above condition (3) in order to reduce the outer diameter of the third lens unit to such an extent that the periphery of the image is not extremely darkened. Is desirable.

In the objective optical system according to the present invention having the above-described configuration, the above-mentioned lens unit (in the case of a positive, negative, positive three-unit configuration,
If the outer diameter is reduced by satisfying the condition (3), the diameter of the optical system can be reduced without reducing the amount of peripheral light.

If the lower limit of the condition (3) exceeds 0, the amount of peripheral light at the wide end becomes small, and the peripheral portion of the image becomes darker than the central portion. If the value exceeds the upper limit of 0.8, the outer diameter of the lens group cannot be sufficiently reduced.

The effect of reducing the diameter of the optical system so as to satisfy the above condition (3) is great in a wide optical system in which the angle of view on the wide-angle side is 80 ° or more. When the angle of view on the wide-angle side of the optical system is 100 ° or more, the effect of reducing the diameter by satisfying the condition (3) is even greater.

In the optical system of the present invention, it is preferable that the following condition (3-1) is satisfied instead of the condition (3). (3-1) 0.1 <H _u / H _s <0.5

The case where the optical system of the present invention is used for an endoscope has been mainly described above. However, in the case of a digital camera, the angle of view is narrower than that of an endoscope, and the amount of generation of distortion is small, so that there is no practical problem. Also, if the distortion is small, there is a concern that the peripheral light quantity is insufficient. However, since the imaging target is not illumination using an illumination device like an endoscope, the state of peripheral dimming is different from that of the endoscope. Therefore, even if the outer diameter of the lens is reduced so as to satisfy the condition (3) in the optical system of the digital camera, the decrease in the amount of peripheral light does not pose a practical problem.

Also, in an endoscope capable of magnifying observation using an objective optical system having a zooming effect by moving at least one lens group on the optical axis, which is composed of a plurality of lens groups, the inside of the body or the like is required. In order to improve insertability into
It is desirable to minimize the outer diameter of the distal end where the objective optical system is disposed.

FIG. 37 shows a cross section of the distal end portion of the endoscope, where 1 is an objective optical system, 2, 3, 4, and 5 are illumination optical systems, and φ (n) and φ (p). Is the diameter of the tip. It is effective to reduce the outer diameter of the objective optical system 1 as described above in order to reduce the diameter of the distal end portion. However, there are other means for reducing the outer diameter of the illumination optical system. That is, FIG.
(A) is an example where the outer diameter of the illumination optical system is large (B)
Shows an example in which the outer diameter of the illumination optical system is small. As shown in this drawing, the endoscope end portion of (A) using the illumination optical systems 2 and 3 has a diameter φ (p) by using the illumination optical systems 4 and 5 having a small diameter as in (B). Can be reduced.

FIG. 38 is a sectional view showing an example of the illumination optical system. In the figure, (A) is an example using a negative lens, 6 is a light guide, and 7 is a lens of an illumination optical system composed of a negative lens. FIG. 38B shows an illumination optical system using the positive lens 8.

Referring to FIGS. 38A and 38B,
The illumination optical system using the negative lens 7 shown in FIG.
The light beam L1 that has exited the gate 6 is the light guide side surface of the negative lens
S2 is diverged, so the object-side surface S of the negative lens 7
1 must have a sufficiently large effective diameter. That
The diameter of the lens becomes large and the diameter φ of the endoscope end (N)
growing.

On the other hand, the illumination optical system using the positive lens 8 as shown in FIG. 38B converges the light L2 and the light L3 emitted from the light guide 6 and irradiates the object with the light. When a light guide having an outer diameter is used, the outer diameter φ _L (p) of the lens is changed to an outer diameter φ _L when a negative lens is used.
It can be smaller than (n). Therefore, it is desirable that at least one illumination optical system be configured to include at least one positive lens. It is desirable that at least one illumination optical system is an optical system having a positive refractive power. In particular, when the optical system has a movable part, a movable mechanism is required, and the end of the endoscope becomes large. Therefore, if the illumination optical system is configured as described above, the outer diameter of the distal end portion of the endoscope can be reduced.

It is further desirable that at least two illumination optical systems include at least one positive lens. It is desirable that at least two illumination optical systems have a positive refractive power.

In the objective optical system of the present invention, in order to shorten the entire length of the optical system, it is desirable to use a refractive index distribution lens having a refractive index distribution in the medium. The refractive index distribution lens has a greater degree of freedom in correcting aberrations than a homogeneous lens, and when applied to the optical system of the present invention, the number of lenses in the optical system can be greatly reduced and the size can be reduced.

The endoscope optical system capable of magnifying and observing an object has a long object distance on the wide side to observe a wide range. On the tele side, the object distance is shortened in addition to the magnification change of the optical system. Observations are made at high magnification of the system. However, if the object distance on the telephoto side is not appropriate, observation at a sufficient magnification cannot be performed.

In the objective optical system of the present invention, when performing observation at a high magnification, it is desirable to satisfy the following condition (4). _{(4) 0.1 <d 0T /} f T <5 However, d _0T the object distance on the telephoto side, the f _T is a focal length of the entire system at the telephoto side.

When the value exceeds the upper limit of 5 of the condition (4), it is difficult to secure a sufficient magnification. The lower limit of 0.1
When the distance exceeds, the object distance is too short, and it is difficult for illumination to reach the observation range.

It is more desirable that the condition (4-1) be satisfied instead of the condition (4). (4-1) 0.2 <d _0T / f _T <3

It is more desirable that the following condition (4-2) is satisfied instead of the condition (4) or the condition (4-1). (4-2) 0.5 <d _0T / f _T <1.5

The objective optical system according to the third configuration of the present invention comprises, in order from the object side, a first group having a positive refractive power and a second group having a negative refractive power.
And a third lens unit having a positive refractive power. The second lens unit performs zooming by moving on the optical axis.
The group includes one negative lens and at least one positive lens, and the third group includes one negative lens and at least one positive lens.

In order to configure the optical system with a smaller number of lenses, and to favorably correct aberrations, the first unit having a high off-axis ray height and a large amount of off-axis aberrations is required to have at least one negative lens and at least one negative lens. It is desirable to configure with one positive lens.

In order to constitute the third lens group having mainly an image forming function and generating relatively large spherical aberration with a small number of lenses, one negative lens and at least one positive lens are required. It is desirable to configure with.

The optical system according to the fourth configuration of the present invention comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. The second unit performs a zooming operation by moving on the optical axis, and has one cemented lens.

Since the objective optical system of the present invention has a wide angle of view, the amount of chromatic aberration of magnification tends to be large. In order to correct this chromatic aberration with a less expensive lens system, it is desirable to use a set of cemented lenses composed of a positive lens and a negative lens in the optical system. In order to give priority to correction of chromatic aberration over cost, it is desirable to use two sets of cemented lenses.

The objective optical system according to the fifth aspect of the present invention comprises, in order from the object side, a first group having a positive refractive power and a second group having a negative refractive power.
And a third lens unit having a positive refractive power. The second lens unit performs zooming by moving on the optical axis.
The group includes, in order from the object side, a negative lens, a parallel plate, at least one optical element, and a brightness stop, and at least one of the optical elements disposed between the parallel plate and the brightness stop has the following conditions. This is an optical system that satisfies (5). (5) DDi <0.2 mm where DDi is the distance between the optical elements of the optical elements disposed between the parallel plate and the aperture stop (the distance between each optical element and the optical elements before and after it). is there.

As shown in FIG. 39, when the first lens unit is composed of a negative lens Ln, a parallel plate P, an optical element LP, and a stop S in order from the object side, between the parallel plate P and the stop S, Distance DD1 or DD before and after the arranged optical element LP
It is preferable that at least one of the two satisfies the condition (5) because the total length of the optical system can be shortened. Condition (5)
Is satisfied, the distance between the first lens Ln and the stop S can be reduced, and the height of off-axis rays passing through the first lens Ln can be reduced, and the outer diameter of the first lens can be reduced. Can be made smaller.

When the angle of view of the optical system is set to a wide angle of view of 120 ° or more, the first group having a positive refractive power and the negative refractive power are arranged in order from the object side, as in the optical system of the present invention. It is desirable that the zoom lens is composed of a second group of power and a third group of positive refractive power, and the second group is moved on the optical axis to perform zooming.

When the angle of view is a wide angle of view of 120 ° or more, it becomes difficult to correct off-axis aberrations. As described above, it is desirable that the objective optical system be arranged symmetrically in order from the object side as a positive lens unit, a negative lens unit, and a positive lens unit, in order to properly correct off-axis aberrations.

In the optical system of each configuration of the present invention, it is desirable to satisfy the above conditions (1) and (2).

It is desirable that the objective optical system of each configuration of the present invention satisfies the condition (3) or the conditions (1), (2) and (3).

Instead of the condition (1), the condition (1-
It is more preferable that the condition (2-1) is satisfied instead of the condition (1) and the condition (2).

Instead of the condition (3), the condition (3-
It is more desirable to satisfy 1).

Further, in the objective optical system of each configuration of the present invention, if the following condition (4-3) is satisfied instead of the condition (4), the condition (4-1) or the condition (4-2), the system is more compact. It is more desirable because the optical system can be made simple. (4-3) 0.75 <d _0T / f _T <1.5

[0052]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the objective optical system according to the present invention will now be described based on the following examples. Example 1 f = 1.49 to 2.94, F / 6.7 to 17.6, 2ω = 113 ° to 35.7 ° Object distance = 14 to 2.5, Image height = 1.205 r ₁ = ∞ d ₁ = 0.4000 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.9925 d ₂ = 0.6239 r ₃ = ∞ d ₃ = 0.6200 n ₂ = 1.51633 ν ₂ = 64.14 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.4000 n ₃ = 1.51633 ν ₃ = 64.14 r ₆ = _{∞ d 6 = 0.2000 r 7 =} ∞ d 7 = 0.3000 n 4 = 1.84666 ν 4 = 23.78 r 8 = 2.2520 d 8 = 0.7000 n 5 = 1.51742 ν 5 = 52.43 r 9 = -2.2520 d 9 = 0.0500 r 10 = 4.0594 _{d 10 = 1.0635 n 6 = 1.60342} ν 6 = 38.03 r 11 = -2.5841 d 11 = 0.0500 r 12 = ∞ ( stop) d ₁₂ = D _{1 (variable) r 13 = -3.5618 d 13 =} 0.3500 n 7 = 1.88300 ν _{7 = 40.76 r 14 = 3.5618 d} 14 = D 2 ( _{variable) r 15 = -42.9033 d 15 =} 0.7420 n 8 = 1.72916 ν 8 = 54.68 r 16 = -3.9283 d 16 = 0.0500 r 17 = 3.9283 d 17 = 0.7420 n ₉ = 1.72916 ν ₉ = 54.68 r ₁₈ = 42.9033 d _{18 = 0.5016 r 19 = -6.1532 d} 19 = 0.3000 n 10 = 1.84666 ν 10 = 23.78 r 20 = 6.1532 d 20 = 0.8660 n 11 = 1.74100 ν 11 = 52.64 r 21 = -9.1990 d 21 = 3.9444 r 22 = ∞ d ₂₂ = 2.8000 n ₁₂ = 1.51633 ν ₁₂ = 64.14 r ₂₃ = ｄ d ₂₃ = 0.7000 n ₁₃ = 1.51633 ν ₁₃ = 64.14 r ₂₄ = ｆ f 1.49 2.94 D ₀ 14.0000 2.5000 D ₁ 0.35000 2.39649 D ₂ 2.54649 0.50000 ｛/ ｛ f ₂ (D _W −D _T )｝ | = 0.25 | (f _W · f _T ) ^1/2 / f ₁ | = 1.37, _Hu / H _s = 0.19, d _0T / f _T = 0.85

Example 2 f = 1.59 to 2.65, F / 7.1 to 16.6, 2ω = 113.6 ° to 37.7 ° Object distance = 14 to 2.5, Image height = 1.2 r ₁ = ∞ d ₁ = 0.4000 n ₁ = 1.88300 v ₁ = 40.78 r ₂ = 0.8683 d ₂ = 0.5046 r ₃ = ∞ d ₃ = 0.6200 n ₂ = 1.51633 ν ₂ = 64.14 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ＝ d ₅ = 0.4000 n ₃ = 1.51633 ν ₃ = 64.14 r ₆ = ∞ d ₆ = 0.2545 r ₇ = 1.2262 d ₇ = 0.5702 n ₄ = 1.90135 ν ₄ = 31.55 r ₈ = 0.6244 d ₈ = 0.8714 n ₅ = 1.58913 ν ₅ = 61.14 r ₉ = -1.4901 d ₉ = 0.0500 r ₁₀ = ∞ (aperture) d ₁₀ = D ₁ (variable) r ₁₁ = −2.106 d ₁₁ = 0.3500 n ₆ = 1.88300 v ₆ = 40.76 r ₁₂ = 5.4229 d ₁₂ = D ₂ (variable) r ₁₃ = 8.2464 d ₁₃ = _{0.7638 n 7 = 1.77250 ν 7 =} 49.60 r 14 = -4.2025 d 14 = 0.1000 r 15 = 3.5102 d 15 = 0.9246 n 8 = 1.65160 ν 8 = 58.55 r 16 = ∞ d 16 = 0.4526 r 17 = -4.4938 d 17 = 0.3000 n ₉ = 1.84666 ν ₉ = 23.78 r ₁₈ = 4.9157 d ₁₈ = 0.7487 n ₁₀ = 1.54072 ν ₁₀ = 47.23 r ₁₉ = -5.4931 d ₁₉ = 1.9510 r ₂₀ = ∞ d ₂₀ = 2.0000 n ₁₁ = 1.51633 ν ₁₁ = 64.14 r ₂₁ = ₂₁ d ₂₁ = 0.7000 n ₁₂ = 1.51633 ν ₁₂ = 64.14 r ₂₂ = ∞ f 1.59 2.65 D ₀ 14.0000 2.5000 D ₁ 0.35000 1.92319 D ₂ 2.07319 0.50000 | 1 / {f ₂ (D _W -D _T )} | = 0.38 | (f _W · f _T ) _{^{1/2 / f 1 | = 1.32,}} H u / H s = 0.12, d 0T / f T = 0.95

Example 3 f = 1.03 to 2.13, F / 6.3 to 19.2, 2ω = 113.1 ° to 29.7 ° Object distance = 9 to 2, Image height = 0.8 r ₁ = ∞ d ₁ = 0.3000 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.7695 d ₂ = 0.5457 r ₃ = ∞d ₃ = 0.6200 n ₂ = 1.51400 ν ₂ = 75.00 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.4000 n ₃ = 1.52287 ν ₃ = 59.89 r ₆ = ∞d ₆ = 0.1000 r ₇ = 4.8121 d ₇ = 1.3697 n ₄ = 1.51633 ν ₄ = 64.14 r ₈ = -2.0089 d ₈ = 0.0500 r ₉ = 2.4698 d ₉ = 0.5000 n ₅ = 1.51633 ν ₅ = 64.14 r _{10 = -5.1287 d 10 = 0.0300 r} 11 = ∞ ( stop) d ₁₁ = D _{1 (variable) r 12 = -1.6604 d 12 =} 0.3000 n 6 = 1.88300 ν 6 = 40.76 r 13 = 3.1025 d 13 = D 2 ( Variable) r ₁₄ = 11.3617 d ₁₄ = 0.6000 n ₇ = 1.88300 ν ₇ = 40.76 r ₁₅ = −3.8018 d ₁₅ = 0.1000 r ₁₆ = 1.9815 d ₁₆ = 0.7000 n ₈ = 1.51633 ν ₈ = 64.14 r ₁₇ = −2.8011 d _{17 = 0.1928 r 18 = -2.2197 d 18} = 0.29 97 n ₉ = 1.84666 v ₉ = 23.78 r ₁₉ = 36.2030 d ₁₉ = 2.6936 r ₂₀ = ∞ d ₂₀ = 2.0000 n ₁₀ = 1.51633 v ₁₀ = 64.14 r ₂₁ = ∞ d ₂₁ = 0.5000 n ₁₁ = 1.51633 v ₁₁ = 64.14 r _{22 = ∞ f 1.03 2.13 D 0} 9.0000 2.0000 D 1 0.20000 1.61610 D 2 1.71610 0.30000 | 1 / {f 2 (D W -D T)} | = 0.59 | (f W · f T) 1/2 / f 1 | _{= 1.48, H u / H s} = 0.28, d 0T / f T = 0.94

Example 4 f = 1.87 to 2.46, F / 8.4 to 17.2, 2ω = 114 ° to 12.1 ° Object distance = 14 to 2.4, Image height = 1.205 r ₁ = ∞ d ₁ = 0.4000 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.8962 d ₂ = 0.5558 r ₃ = ∞ d ₃ = 0.6200 n ₂ = 1.51633 ν ₂ = 64.14 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ＝ d ₅ = 0.4000 n ₃ = 1.51633 ν ₃ = 64.14 r ₆ = ∞ d ₆ = 0.0500 r ₇ = 1.7480 d ₇ = 0.6384 n ₄ = 1.85026 ν ₄ = 32.29 r ₈ = 1.1023 d ₈ = 1.3177 n ₅ = 1.51633 ν ₅ = 64.14 r ₉ = −2.2516 d ₉ = 0.0500 r _{10 = 5.0089 d 10 = 0.2999 n} 6 = 1.81600 ν 6 = 46.62 r 11 = 1.7427 d 11 = 0.9000 n 7 = 1.51633 ν 7 = 64.14 r 12 = -4.2864 d 12 = 0.0500 r 13 = 6.1780 d 13 = 0.5000 n 8 _{= 1.51633 ν 8 = 64.14 r 14} = 20.6106 d 14 = D 1 ( variable) r ₁₅ = ∞ _{(stop) d 15 = 0.1000 r 16 =} -4.7731 d 16 = 0.3000 n 9 = 1.88300 ν 9 = 40.76 r 17 = 2.2863 d ₁₇ = D ₂ (variable) _{18 = 8.4983 d 18 = 0.9000 n} 10 = 1.54072 ν 10 = 47.23 r 19 = -4.1683 d 19 = 0.0500 r 20 = 5.0624 d 20 = 0.8000 n 11 = 1.51633 ν 11 = 64.14 r 21 = 26.5610 d 21 = 0.0500 r 22 _{= 2.8523 d 22 = 1.7156 n 12} = 1.51633 ν 12 = 64.14 r 23 = -4.2658 d 23 = 0.4580 n 13 = 1.84666 ν 13 = 23.78 r 24 = 3.6816 d 24 = 3.1035 r 25 = ∞ d 25 = 2.0000 n 14 = 1.51633 ν ₁₄ = 64.14 r ₂₆ = ∞ d ₂₆ = 0.7000 n ₁₅ = 1.51633 ν ₁₅ = 64.14 r ₂₇ = ∞ f 1.87 2.46 D ₀ 14.0000 2.4000 D ₁ 0.30000 3.08339 D ₂ 3.08339 0.30000 │1 / ｛f ₂ (D _W − _{D T)} | = 0.21 |} (f W · f T) 1/2 / f 1 | = 1.14, H u / H s = 0.11, d 0T / f T = 0.97

Example 5 f = 1.07 to 1.70, F / 7.2 to 11.4, 2ω = 113.5 ° to 32.9 ° Object distance = 9 to 2, Image height = 0.8 r ₁ = ∞ d ₁ = 0.3000 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.5012 d ₂ = 0.6125 r ₃ = ∞ d ₃ = 0.9539 n ₂ = 1.61800 ν ₂ = 63.33 r ₄ = -1.1459 d ₄ = 0.0500 r ₅ = 2.6528 d ₅ = 0.5000 n ₃ = 1.51633 ν ₃ = 64.14 r ₆ = -2.7819 d ₆ = D ₁ (variable) r ₇ = ∞ (aperture) d ₇ = 0.1000 r ₈ = -2.4333 d ₈ = 0.3000 n ₄ = 1.88300 v ₄ = 40.76 r ₉ = 1.6593 d ₉ = D ₂ (variable) r ₁₀ = 1.2526 (aspherical surface) d ₁₀ = 0.7000 n ₅ = 1.88300 ν ₅ = 40.76 r ₁₁ = -2.1707 d ₁₁ = 0.1757 r ₁₂ = -1.6001 d ₁₂ = 0.2995 n ₆ = 1.84666 ν ₆ = 23.78 r ₁₃ = 3.5760 d ₁₃ = 0.2000 r ₁₄ = ∞ d ₁₄ = 0.6200 n ₇ = 1.51400 ν ₇ = 75.00 r ₁₅ = ∞ d ₁₅ = 0.0300 r ₁₆ = ∞ d ₁₆ = 0.4000 n ₈ = 1.52287 ν ₈ = 59.89 r ₁₇ = ∞ d ₁₇ = 1.1229 r ₁₈ = ∞ d ₁₈ = 1.2000 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₉ = ∞ d ₁₉ = 0.5000 n ₁₀ = 1.51633 ν ₁₀ = 64.14 r ₂₀ = ∞ Aspherical coefficient A ₄ = −8.6636 × 10 ⁻² , A ₆ = −3.4303 × 10 ^-2 f 1.07 1.70 D ₀ 9.0000 2.0000 D ₁ 0.20000 1.20746 D ₂ 1.30746 0.30000 | 1 / {f ₂ (D _W -D _T )} | = 0.92 | (f _W · f _T ) ^1/2 / f ₁ | = _{1.45, H u / H s =} 0.16, d 0T / f T = 1.18

Example 6 f = 1.50 to 2.61, F / 7.1 to 17.7, 2ω = 113.1 ° to 37.2 ° Object distance = 13.4 to 2.35, Image height = 1.205 r ₁ = ∞ d ₁ = 0.3500 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 1.0553 d ₂ = 0.9677 r ₃ = ∞d ₃ = 0.6200 n ₂ = 1.51400 ν ₂ = 75.00 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.4000 n ₃ = 1.52287 ν ₃ = 59.89 r ₆ = ∞d ₆ = 0.1000 r ₇ = ∞ d ₇ = 2.6391 n ₄ (refractive index distribution lens) r ₈ = -2.6614 d ₈ = 0.1000 r ₉ = ∞ (aperture) d ₉ = D ₁ (variable) r _{10 = -4.1954 d 10 = 0.3500 n 5} = 1.88300 ν 5 = 40.76 r 11 = 4.2915 d 11 = D 2 ( _{variable) r 12 = 4.4231 d 12 =} 0.9000 n 6 = 1.51633 ν 6 = 64.14 r 13 = -3.8049 d 13 _{= 0.0500 r 14 = 3.6296 d 14} = 1.0000 n 7 = 1.51633 ν 7 = 64.14 r 15 = -6.0097 d 15 = 0.2818 r 16 = -3.3067 d 16 = 1.6846 n 8 = 1.84666 ν 8 = 23.78 r 17 = ∞ d 17 = 2.7940 r ₁₈ = ∞ d ₁₈ = 2.1 000 n ₉ = 1.51633 v ₉ = 64.14 r ₁₉ = ∞ d ₁₉ = 0.9800 n ₁₀ = 1.51633 v ₁₀ = 64.14 r ₂₀ = ∞ f 1.50 2.61 D ₀ 13.4000 2.3500 D ₁ 0.20000 2.48900 D ₂ 2.48900 0.20000 Refractive index distribution lens N ₀ N ₁ N ₂ d line 1.65000 -4.0000 × 10 ^-2 -1.0542 × 10 ^-3 C line 1.64567 -3.9960 × 10 ^-2 -1.0531 × 10 ^-3 F line 1.66011 -4.0093 × 10 ^-2 -1.0566 × 10 ^-3 | 1 / {f ₂ (D _W −D _T )} | = 0.19 | (f _W · f _T ) ^1/2 / f ₁ | = 1.21, H _u / H _s = 0.62, d _0T / f _T = 0.90

Example 7 f = 1.46 to 2.76, F / 7.1 to 16.5, 2ω = 112.9 ° to 41.1 ° Object distance = 13.4 to 2.35, Image height = 1.205 r ₁ = ∞ d ₁ = 0.3500 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.7822 d ₂ = 0.5642 r ₃ = ∞ d ₃ = 0.6200 n ₂ = 1.51400 ν ₂ = 75.00 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.4000 n ₃ = 1.52287 ν ₃ = 59.89 r ₆ = ∞ d ₆ = 0.0500 r ₇ = ∞ d ₇ = 0.6449 n ₄ = 1.51742 ν ₄ = 52.43 r ₈ = -1.6249 d ₈ = 0.0500 r ₉ = 5.2248 d ₉ = 0.5000 n ₅ = 1.51633 ν ₅ = 64.14 r _{10 = -2.6718 d 10 = 0.0500 r} 11 = ∞ ( stop) d ₁₁ = D _{1 (variable) r 12 = -3.2106 d 12 =} 0.3000 n 6 = 1.88300 ν 6 = 40.76 r 13 = 3.7268 d 13 = D 2 ( _{variable) r 14 = 5.1723 d 14 =} 5.2987 n 7 ( gradient index _{lens) r 15 = ∞ d 15 =} 2.9044 r 16 = ∞ d 16 = 2.1000 n 8 = 1.51633 ν 8 = 64.14 r 17 = ∞ d 17 = 0.9800 n ₉ = 1.51633 ν ₉ = 64.14 r _{18 = ∞ f 1.46 2.76 D 0} 13.4000 2.3500 D 1 0.30000 2.03085 D 2 2.03085 0.30000 refractive index lens N ₀ N ₁ N ₂ d-ray ^{1.70000 -2.0000 × 10 -2 3.6899 × 10} -4 C line 1.69475 -2.0060 × 10 ^{- 2} 3.6899 × 10 ^-4 F line 1.71225 -1.9860 × 10 ^-2 3.6899 × 10 ^-4 | 1 / {f ₂ (D _W −D _T )} | = 0.30 | (f _W · f _T ) ^1/2 / f _{1 | = 1.36, H u /} H s = 0.36, d 0T / f T = 0.85

Example 8 f = 1.83 to 2.13, F / 8.9 to 12.3, 2ω = 131 ° to 75.3 ° Object distance = 14.4 to 2.0, Image height = 1.61r ₁ = ∞ d ₁ = 0.3800 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 1.0600 d ₂ = 0.7200 r ₃ = ∞ d ₃ = 0.4000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.6200 n ₃ = 1.51400 ν ₃ = 75.00 r ₆ = ∞ d ₆ = 0.0500 r ₇ = 3.1860 d ₇ = 1.5100 n ₄ = 1.72916 ν ₄ = 54.68 r ₈ = -2.3660 d ₈ = 0.0500 r ₉ = ∞ (aperture) d ₉ = D ₁ (variable) r _{10 = ∞ d 10 = 0.2800 n 5} = 1.59551 ν 5 = 39.24 r 11 = 2.9200 d 11 = 0.1800 r 12 = ∞ d 12 = D 2 ( _{variable) r 13 = ∞ d 13 =} -0.0800 r 14 = 4.2960 d 14 = _{1.8000 n 6 = 1.72916 ν 6 =} 54.68 r 15 = -2.0850 d 15 = 0.3200 n 7 = 1.84666 ν 7 = 23.78 r 16 = -5.8750 d 16 = 2.0900 r 17 = ∞ d 17 = 1.2000 n 8 = 1.51633 ν 8 = 64.14 r ₁₈ = ∞ d ₁₈ = 0.0100 n ₉ = 1.5 6384 ν ₉ = 60.67 r ₁₉ = ∞ d ₁₉ = 1.2000 n ₁₀ = 1.53172 ν ₁₀ = 48.84 r ₂₀ = ∞ d ₂₀ = 0.0300 n ₁₁ = 1.56384 ν ₁₁ = 60.67 r ₂₁ = ∞ f 1.83 2.13D ₀ 14.40000 2.00000 D ₁ 0.20000 2.09000 D ₂ 2.2000 0.31000 | 1 / {f ₂ (D _W -D _T )} | = 0.11 | (f _W · f _T ) ^1/2
_{/ f 1 | = 0.89, H} u / H s = 0.36, d 0T / f T = 0.94 β 2W = 8.30, φ3-φFS = 0.6mm

Example 9 f = 1.97 to 2.52, F / 9.2 to 15.6, 2ω = 129.9 ° to 56.3 ° Object distance = 15 to 2.0, Image height = 1.61 r ₁ = ∞ d ₁ = 0.4000 n ₁ = 1.8 8300 ν ₁ = 40.78 r ₂ = 1.0945 d ₂ = 0.8692 r ₃ = ∞ d ₃ = 0.4000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.6200 n ₃ = 1.51400 ν ₃ = 75.00 r ₆ = ∞ d ₆ = 0.1000 r ₇ = 2.1389 d ₇ = 0.5000 n ₄ = 1.88300 ν ₄ = 40.76 r ₈ = 1.0592 d ₈ = 1.4605 n ₅ = 1.63930 ν ₅ = 44.87 r ₉ = -2.1142 d ₉ = 0.1000 r ₁₀ = ∞ (aperture) d ₁₀ = D ₁ (variable) r ₁₁ = -59.6121 d ₁₁ = 0.3000 n ₆ = 1.88300 ν ₆ = 40.76 r ₁₂ = 3.8932 d ₁₂ = D ₂ (variable) r ₁₃ = 4.3415 d ₁₃ = 1.5693 n ₇ = 1.77250 ν ₇ = 49.60 r ₁₄ = -2.1637 d ₁₄ = 0.2810 n ₈ = 1.90135 ν ₈ = 31.55 r ₁₅ = -7.3937 d ₁₅ = 3.4307 r ₁₆ = ∞ d ₁₆ = 1.5000 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₇ = ∞ d ₁₇ = 1.2500 n ₁₀ = 1.51633 ν ₁₀ = 64.14 r ₁₈ = ∞ f 1.97 2.52 D ₀ 15.00000 2.00000 D ₁ 0.20000 2.69967 D ₂ 2.74757 0.25000 | 1 / {f ₂ (D _W -D _T )} | = 0.1 0 | (f _W・ f _T ) ^1/2 / f ₁ | = 0.95, H _u / H _s = 0.11, d _0T / f _T = 0.7
9, β _2W = 2.1

Example 10f = 1.14 to 1.53, F / 7.3 to 12, 2ω = 132.9 ° to 65.3 ° Object distance = 12 to 2.2, Image height = 1.05 r₁ = ∞ d₁ = 0.2600 n₁ = 1.8 8300 ν₁ = 40.78 r_Two = 0.7216 d_Two = 0.4587 r_Three = ∞ d_Three = 0.4000 n_Two = 1.52287 ν_Two = 59.89 r_Four = ∞ d_Four = 0.0300 r_Five = ∞ d_Five = 0.6200 n_Three = 1.51400 ν_Three = 75.00 r₆ = ∞ d₆ = 0.0400 r₇ = 3.6037 d₇ = 0.6175 n_Four = 1.88300 ν_Four = 40.76 r₈ = -1.8142 d₈ = 0.0500 r₉= ∞ (aperture) d₉ = D₁ (Variable) r_Ten = -8.7484 d_Ten = 0.2000 n_Five = 1.90135 ν_Five = 31.55 r₁₁= 2.5880 d₁₁= D_Two (Variable) r₁₂= ∞ d₁₂= 0.0000 r₁₃= 3.6204 d₁₃= 0.6208 n₆ = 1.88300 ν₆ = 40.76 r₁₄= -3.7375 d₁₄= 0.0500 r_Fifteen= 4.4029 d_Fifteen= 0.8061 n ₇ = 1.51633 ν₇ = 64.14 r₁₆= -1.6972 d₁₆= 0.2000 n₈ = 1.84666 ν₈ = 23.78 r₁₇= 39.0105 d₁₇= 1.2038 r₁₈= ∞ d₁₈= 1.1000 n₉ = 1.51633 ν₉ = 64.14 r₁₉= ∞ d₁₉= 0.8000 n_Ten= 1.51633 ν_Ten= 64.14 r₂₀= ∞ f 1.14 1.53 D₀ 12.00000 2.20000 D₁ 0.15000 1.32311 D_Two 1.32311 0.15000 | 1 / {f_Two (D_W -D_T )} | = 0.39 | (f_W ・ F_T )^1/2 / f₁ | = 0.90, H_u / H_s = 0.44, d_0T/ f_T =
1.44 β_2W= 1.36, φ3-φFS = 0.4mm

Example 11f = 1.35 to 2.04, F / 6.4 to 11.7,
2ω = 130 ° -56.6 ° Object distance = 12-2.1, Image height = 1.21 r₁ 
= ∞ d₁ = 0.3000 n₁ = 1.8 8300 ν₁ = 40.78 r_Two = 0.7564 d_Two = 0.5000 r_Three = ∞ d_Three = 0.4000 n_Two = 1.52287 ν_Two = 59.89 r_Four = ∞ d_Four = 0.0300 r_Five = ∞ d_Five = 0.6200 n_Three = 1.51400 ν_Three = 75.00 r₆ = ∞ d₆ = 0.0500 r₇ = 16.9172 d₇ = 0.6000 n_Four = 1.51633 ν_Four = 64.14 r₈ = -1.5139 d₈ = 0.0500 r₉ = 5.5489 d₉ = 0.5000 n_Five = 1.51633 ν_Five = 64.14 r_Ten= -2.7205 d_Ten= 0.5000 r_Ten= ∞ (aperture) d₁₁= D₁ (Variable) r₁₂ = -6.2390 d₁₂= 0.2500 n₆ = 1.88300 ν₆ = 40.76 r₁₃= 2.6147 d₁₃= D_Two (Variable) r₁₄= 6.1306 d₁₄= 1.1000 n₇ = 1.72916 ν₇ = 54.68 r_Fifteen= -1.5473 d_Fifteen= 0.2500 n₈ = 1.84666 ν₈ = 23.78 r₁₆= -3.6654 d₁₆= 0.0500 r₁₇= 6.0286 d₁₇= 0.6288 n ₉ = 1.51633 ν₉ = 64.14 r₁₈= ∞ d₁₈= 2.9631 r₁₉= ∞ d₁₉= 1.5000 n_Ten= 1.51633 ν_Ten = 64.14 r₂₀= ∞ d₂₀= 1.0000 n₁₁= 1.51633 ν₁₁ = 64.14 r_{twenty one}= ∞ f 1.35 2.04 D₀ 12.00000 2.10000 D₁ 0.20000 1.54000 D_Two 1.59000 0.25000 | 1 / {f_Two (D_W -D_T )} | = 0.36 | (f_W ・ F_T )^1/2 / f₁ | = 1.17, H_u / H_s = 0.52, d_0T/ f_T = 1.
03, β_2W= 1.14

Example 12f = 1.21 to 1.48, F / 6.8 to 9.7, 2ω = 149.6 ° to 76.3 ° Object distance = 12 to 1.9, Image height = 1.1 r ₁ = ∞ d ₁ = 0.2500 n ₁ = 1.8830 0 ν ₁ = 40.78 r ₂ = 0.7403 d ₂ = 0.4194 r ₃ = ∞ d ₃ = 0.2000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0500 r ₅ = 2.1275 d ₅ = 1.7387 n ₃ = 1.68893 ν ₃ = 31.07 r ₆ = -1.3323 d ₆ = 0.0500 r ₇ = ∞ (aperture) d ₇ = D ₁ (variable) r ₈ = 282.6298 d ₈ = 0.2000 n ₄ = 1.84666 ν ₄ = 23.78 r ₉ = 2.6319 d ₉ = D ₂ (variable) r ₁₀ = 4.5636 d ₁₀ = 0.8674 n ₅ = 1 88300 ν ₅ = 40.76 r ₁₁ = -1.7560 d ₁₁ = 0.2000 n ₆ = 1.84666 ν ₆ = 23.78 r ₁₂ = -4.2149 d ₁₂ = 0.1000 r ₁₃ = Ｄ d ₁₃ = 0.6200 n ₇ = 1.51400 ν ₇ = 75.00 r ₁₄ = ∞ d ₁₄ = 1.2120 r ₁₅ = ∞ d ₁₅ = 1.0000 n ₈ = 1.51633 ν ₈ = 64.14 r ₁₆ = ∞ d ₁₆ = 0.5000 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₇ = ∞ f 1.21 1.48 D ₀ 12.00000 1.90000 D ₁ 0.10000 1.35581 D ₂ 1.40581 0.15000 | 1 / {f ₂ (D _W -D _T )} | = 0.25 | (f _W · f _T ) ^1/2 / f ₁ | = 0.79, H _u / H _s = 0.45, d _0T / f _T = 1.28, β _2W = 3.63 where r ₁ , r ₂ ,... are the radii of curvature of the respective surfaces of the lens, d
_.. , D ₂ ,...
₁ , n ₂ ,... Are the refractive indices of each lens, ν ₁ , ν ₂ ,.
Is the Abbe number of each lens. D ₀ is the object distance.
The unit of the length in the data is mm.

In the first embodiment, the configuration shown in FIG. 1 is shown, (A) shows the wide-angle end, and (B) shows the telephoto end. As shown, the first embodiment includes, in order from the object side, a first group G1 having a positive refractive power, a second group G2 having a negative refractive power, and a third group G3 having a positive refractive power.

The first unit includes, in order from the object side, a negative lens,
It is composed of a junction of a negative lens and a positive lens, and a positive lens, and has an action of guiding on-axis rays and off-axis rays to the second group. Each of the parallel plane plates F1 and F2 in the first group is a filter for cutting a specific wavelength, for example, 1060 nm of a YAG laser, 810 nm of a semiconductor laser, or an infrared region. In addition, the curvature radii of both surfaces of the positive lens of the cemented lens are made equal to have a configuration advantageous for processing. The second group is composed of one negative lens, and has a zooming effect by moving on the optical axis. In addition, the curvature radii of both surfaces of the negative lens are made equal to make a configuration advantageous for reduction of processing cost and prevention of erroneous assembly. The third group is composed of, in order from the object side, a positive lens, a positive lens, and a cemented lens of a negative lens and a positive lens, and has an action of imaging the divergent light flux from the second group. . The two positive lenses on the object side have the same shape and the same refractive index. In addition, the negative lens has the same curvature radius on both surfaces, and is advantageous in processing and assembling. In the optical system according to the first embodiment, the aperture stop S is disposed between the first and second units. Condition (1),
By satisfying (2), it has become possible to shorten the overall length while favorably correcting various aberrations.

By satisfying the condition (3), the outer diameter is reduced. In FIG. 1, a light ray L (1) is a light ray when an off-axis upper ray passes through the aperture stop to the full diameter of the aperture stop,
The ray L (2) is an off-axis upper ray when the diameter of the third lens unit is reduced. As is clear from this figure, when the light beam is fully transmitted through the aperture stop, the outside diameter of the lens of the third lens group becomes larger as shown by a broken line. Therefore, if the outer diameter is reduced within a range that satisfies the condition (3), the outer diameter of the third lens unit can be reduced. Further, in this embodiment, off-axis rays are blocked by the field stop FS arranged in the third lens unit so as to reduce the outer diameter of the third lens unit.

FIGS. 13 and 14 show the aberration states of the first embodiment.
As shown in FIG.

The second embodiment has a configuration as shown in FIG. 2 and includes, in order from the object side, a first unit G1 having a positive refractive power, a second unit G2 having a negative refractive power, and a third unit G3 having a positive refractive power. G3. The operation of each group is the same as that of the first embodiment.

The first unit includes a negative lens and a cemented lens of a negative lens and a positive lens in order from the object side, the second unit includes one negative lens, and the third unit includes a positive lens in order from the object side. ,
It is composed of a positive lens and a cemented lens of a negative lens and a positive lens. The aperture stop S is disposed between the first group and the second group. This embodiment is different from the first embodiment in that
The number of lenses in the group is reduced by one.

The second embodiment satisfies the conditions (1) and (2), thereby enabling the overall length to be shortened while favorably correcting various aberrations, and the overall length is 18.3 mm. Further, the outer diameter is reduced by satisfying the condition (3), and the outer diameter of the lens is 3.2 mm. Condition (4)
By satisfying the above condition, the zoom lens has a sufficient magnification observation magnification at the telephoto end.

The aberration states of the second embodiment are as shown in FIGS.

In the third embodiment, as shown in FIG. 3, in order from the object side, a first unit G1 having a positive refractive power, a second unit G2 having a negative refractive power, and a third unit G3 having a positive refractive power. The operation of each group is almost the same as in the first embodiment.

The first unit includes a negative lens, a positive lens, and a positive lens in order from the object side, and the second unit includes a negative lens 1
The third lens unit includes, in order from the object side, a positive lens, a positive lens, and a negative lens. or,
The aperture stop S is arranged between the first group and the second group.

In the third embodiment, the conditions (1) and (2)
By satisfying the above conditions, the overall length is shortened while various aberrations are favorably corrected, and the overall length of the lens system is 13.2 mm.
By satisfying the condition (3), the outer diameter is reduced, and the outer diameter of the lens is 2.2 mm. By satisfying the condition (4), a sufficient magnification magnification is obtained at the telephoto end.

The aberration states of the third embodiment are as shown in FIGS.

In the fourth embodiment, as shown in FIG. 4, the first unit G1 having a positive refractive power and the second unit G1 having a negative refractive power are arranged in order from the object side.
2 and a third group G3 having a positive refractive power. The operation of each group is the same as that of the first embodiment. The aperture stop S is composed of the first group and the second group.
Located between groups.

The first unit of the fourth embodiment includes, in order from the object side, a negative lens, a cemented lens in which a negative lens and a positive lens are cemented, a cemented lens in which a negative lens and a positive lens are cemented, and a positive lens. The second group includes one negative lens, and the third group includes, in order from the object side, a positive lens, a positive lens,
It is composed of a cemented lens in which a positive lens and a negative lens are cemented.

The optical system of the fourth embodiment satisfies the conditions (1)
By satisfying (2) and (3), the overall length is shortened while various aberrations are favorably corrected, and the outer diameter is reduced. Each of the two cemented lenses in the first group has the refractive index of the negative lens higher than that of the positive lens, thereby favorably correcting the Petzval sum which is overcorrected in the entire system.

In general, the endoscope objective optical system has a fixed aperture diameter due to the limitation of the outer diameter. However, in the optical system of the present invention, it is disposed between the first and second lens groups. If the zoom ratio is increased with the aperture diameter fixed, the F
The number becomes extremely large, and the image may be blurred due to diffraction.

For this reason, when the influence of this diffraction becomes a problem in the optical system of the present invention, it is desirable to move the second unit and the stop together during zooming. With such a configuration, it is possible to increase the diameter of the light beam on the telephoto side, and it is possible to prevent image deterioration due to diffraction.

The aberration states of the fourth embodiment are as shown in FIGS. 19 and 20.

The fifth embodiment has a configuration as shown in FIG. 5 and includes a first group G1 having a positive refractive power, a second group G2 having a negative refractive power, and a third group G3 having a positive refractive power. The operation of each of these groups is almost the same as in the first embodiment.

The first lens unit includes a negative lens in order from the object side,
The second lens unit includes a positive lens and a positive lens.
The third lens unit includes a positive lens and a negative lens in order from the object side, and the aperture stop S is disposed between the first lens unit and the second lens unit. An aspherical surface is provided in the third lens unit, and the aspherical surface satisfactorily corrects negative spherical aberration particularly occurring in this lens unit. In order to correct the spherical aberration in this manner, it is desirable that the aspherical surface has a shape such that the positive refractive power decreases from the optical axis toward the peripheral portion.

The shape of the aspherical surface used in this embodiment is approximated by the following equation (a). ^{x = (y 2 / r)} / [1+ {1-P (y / r) 2} 1/2] + ΣA 2i y 2 (a) provided that the formulas (a) the y axis represents the x-axis direction of the optical axis Is taken in the direction perpendicular to the optical axis, where r is the radius of curvature on the optical axis, P is the conic constant, and A _2i is the aspheric coefficient. The values of P, A _{2i and the} like in this embodiment are as shown in the data.

In the fifth embodiment, a filter F3 for cutting a specific wavelength is disposed on the image side of the third group.

The aberration conditions in the fifth embodiment are shown in FIGS.
As shown in FIG.

In the sixth embodiment, as shown in FIG. 6, a first unit G1 having a positive refractive power and a second unit G2 having a negative refractive power are arranged in order from the object side.
And a third group G3 having a positive refractive power. The operation of each group is substantially the same as that of the first embodiment. The first unit includes a negative lens and a positive lens in order from the object side, and the second unit includes a negative lens 1.
The third unit includes, in order from the object side, a positive lens, a positive lens, and a negative lens. The aperture stop S is the first
It is located between the group and the second group. The positive lens in the first group is a so-called radial type refractive index distribution lens having a refractive index in a radial direction from the optical axis. The radial type gradient index lens used in this embodiment has a distribution in which the refractive index decreases from the optical axis toward the periphery, and has an effect of correcting spherical aberration particularly occurring on the telephoto side.

The refractive index distribution of the radial type gradient index lens in this embodiment is approximated by the following equation (b). N (r) = N ₀ + N ₁ r ² + N ₂ r ⁴ +... (B) where N ₀ is the refractive index on the optical axis, N ₁ , N ₂ ,. .., R is the distance from the optical axis in the radial direction. N ₀ , N ₁ , N _{2 of the} sixth embodiment
Are shown in the data.

In the sixth embodiment, by satisfying the conditions (1) and (2), it becomes possible to shorten the overall length while favorably correcting various aberrations. By satisfying the condition (3), the outer diameter is reduced.

FIGS. 23 and 24 show the aberration states of the sixth embodiment.
As shown in FIG.

In the seventh embodiment, as shown in FIG. 7, the first unit G1 having a positive refractive power and the second unit G1 having a negative refractive power are arranged in order from the object side.
2 and a third group G3 having a positive refractive power. The operation of each group is almost the same as that of the first embodiment.

The first unit includes, in order from the object side, a negative lens, a positive lens, and a positive lens, the second unit includes one negative lens, and the third unit includes one positive lens. The aperture stop S is arranged between the first and second lens units.
In this embodiment, the third unit is constituted by one radial type gradient index lens which is approximated by the equation (b). This refractive index distribution lens has a distribution in which the refractive index decreases from the optical axis toward the periphery, and has an effect of correcting spherical aberration particularly occurring on the telephoto side. The values such as the distribution coefficient of the radial type gradient index lens are as shown in the data.

In the seventh embodiment, by satisfying the conditions (1) and (2), it becomes possible to satisfactorily correct various aberrations and shorten the overall length. Further, by satisfying the condition (3), the outer diameter is reduced.

FIGS. 25 and 2 show the aberration states of the seventh embodiment.
6.

The objective optical system according to the eighth embodiment of the present invention has a configuration as shown in FIG. 8 and has the first positive refractive power in order from the object side.
The zoom lens includes a group G1, a second group G2 having a negative refractive power, and a third group G3 having a positive refractive power. The first group G1 includes a negative lens L11 and a positive lens L12, and the second group G2 includes a negative lens L21.
The third group G3 is composed of a cemented lens in which a positive lens L31 and a negative lens L32 are cemented in order from the object side.

Further, the aperture stop S is disposed between the first group G1 and the second group G2. The first group G1 includes a negative lens L11, a parallel flat plate F1, a parallel flat plate F2, and a positive lens L12.
A parallel plate F2, which is an optical element disposed between the parallel plate F1 and the stop S, and a positive lens L.
12 are configured to satisfy the condition (5). As described above, the optical system of the eighth embodiment is compact by satisfying the condition (5).

A flare stop (r ₁₃ ) is provided closest to the image side of the second lens unit G2. In FIG. 8, C1 is a dust cover glass, C2 is a cover glass of an image sensor such as a CCD, and CE1 and CE2 are adhesive layers. Also, the first group G1
The two parallel plates in the middle are filters for cutting light in a specific wavelength range. In order from the object side, the filter F1 is an interference type laser cut filter, and the filter 2 is an absorption type infrared cut filter.

In order to make the objective optical system of the present invention as shown in this embodiment compact,
The magnification β _2W at the wide-angle end of the second lens unit G2 is as follows:
It is desirable to satisfy (6) 1 <| β _2W |

By arranging the flare stop FS (r ₁₃ ) on the object side of the third group G3, the outer diameter of the lens of the third group G3 can be reduced. In this case, if the difference between the inner diameter φFS of the flare stop FS and the outer diameter φ3 of the lens having the smallest outer diameter in the third group G3 is too small, the light outside the field of view hits the lens side surface of the third group G3. Flares occur.

Therefore, in the optical system of the present invention as shown in this embodiment, it is desirable to satisfy the following condition (7). (7) 0.1 mm <φ3-φFS <1.2 mm

If the lower limit of 0.1 mm of the condition (7) is exceeded, flare may occur in the third lens unit G3. If the upper limit of 1.2 mm is exceeded, the outer diameter of the lens of the third group G3 becomes large, and a compact optical system cannot be obtained.

The objective optical system according to the eighth embodiment includes a lens L3
2 diameter φ3 = 3.2 mm, φFS = 2.6 mm, φ3-
φFS = 0.6 mm. It is more preferable that the following condition (7-1) is satisfied instead of the condition (7). (7-1) 0.3mm <φ3-φFS <0.8mm

The flare stop used in the optical system of the eighth embodiment is formed of a thin plate. However, the flare stop can be formed by providing a lens frame with a projection protruding inward.

Further, it is also possible to have a function as a flare stop by forming a stop having a light blocking effect on the lens surface by vapor deposition or printing. The aberration states of the eighth embodiment are as shown in FIGS.

Embodiment 9 of the objective optical system according to the present invention, as shown in FIG. 9, is a first group G1 having a positive refractive power, in order from the object side.
And a second group G2 having a negative refractive power and a third group G3 having a positive refractive power.

The first group G1 includes, in order from the object side, a negative lens L11 and a cemented lens obtained by cementing the negative lens L12 and the positive lens L13. The second group G2 is composed of one negative lens L21. The third unit G3 includes, in order from the object side, a cemented lens formed by cementing a positive lens L31 and a negative lens L32.

In the optical system of the ninth embodiment, the number of lenses is six.
With a small number of lenses and a compact configuration, the optical properties are also good. The aberration states of the ninth embodiment are as shown in FIGS.

Embodiment 10 of the present invention has the configuration shown in FIG.

The tenth embodiment, as shown in FIG.
In order from the object side, there are a first group G1 having a positive refractive power, a second group G2 having a negative refractive power, and a third group G3 having a positive refractive power. The first group G1 includes a negative lens L11 in order from the object side.
The second group G2 includes one negative lens L21. The third group G3 includes a positive lens L31, a positive lens L32, and a negative lens L3 in order from the object side.
3 is joined with a cemented lens.

The optical system of the tenth embodiment is a high-performance and compact optical system that satisfies the above-mentioned conditions, even though the number of lenses is as small as six.

In the optical system of the tenth embodiment, the aperture stop S is disposed between the first unit G1 and the second unit G2, and the third unit G3
By using two positive lenses, the spherical aberration at the telephoto end and the coma at the wide-angle end are favorably corrected.

Further, the flare stop F is located on the object side of the third lens unit G3.
S is arranged. The inner diameter φFS of this flare stop is 1.
The outer diameter φ3 of the positive lens L31 adjacent to the flare stop FS in the third group G3 is 2.0 mm. That is, φ3-φFS = 0.4 mm. The aberration states of the tenth embodiment are as shown in FIGS.

The optical system according to the eleventh embodiment of the present invention, as shown in FIG. 11, has, in order from the object side, a first group G1 having a positive refractive power.
And a second group G2 having a negative refractive power and a third group G having a positive refractive power.
It consists of three.

The first group G1 includes, in order from the object side, a negative lens L11, a positive lens L12, and a positive lens L13. The second group G2 includes one negative lens L21. The group G3 includes, in order from the object side, a cemented lens formed by bonding a positive lens L31 and a negative lens L32, and a positive lens L33.

The eleventh embodiment also satisfies the conditions described above, and is a compact optical system having good optical performance.

Further, the aperture stop S is disposed between the first group G1 and the second group G2, and two positive lenses L1 and L2 are used in the first group G1 to provide spherical aberration at the telephoto end. And the coma at the wide-angle end is favorably corrected. The aberration states of the eleventh embodiment are as shown in FIGS.

Embodiment 12 of the present invention has the configuration shown in FIG.

The optical system according to the twelfth embodiment is arranged in order from the object side.
A first group G1 having a positive refractive power and a second group G2 having a negative refractive power
And a third group G3 having a positive refractive power. The first group G
1 is a negative lens L11 and a positive lens L12 in order from the object side.
The second group G2 is composed of 211 negative lenses, and the third group G3 is composed of a cemented lens in which a positive lens L31 and a negative lens L32 are cemented in order from the object side. The aperture stop S is arranged between the first group G1 and the second group G2. The aberration states of the twelfth embodiment are as shown in FIGS.

The third group G3 of the eighth embodiment is provided on the object side.
The position of the flare stop FS is the convex surface on the object side of the third lens unit G3.
r₁₄Is located closer to the image side than the surface top. Therefore spacing
d ₁₃(Flare aperture FS (r₁₃) And convex surface r₁₄Distance on the optical axis of
Distance) is the distance measured from the image side to the object side.
In the data, a minus (-) sign is attached.

Further, the flare aperture FS (r ₁₂ ) of the tenth embodiment is used.
Corresponds to the vertex of the third-group object-side convex surface (r ₁₃ ), and therefore d ₁₂ in the data is d ₁₂ = 0.

Sectional views showing these embodiments (FIGS. 1 to 7)
In each case, (A) is the wide-angle end and (B) is the telephoto end.

FIG. 40 is a view showing an example of an illumination optical system used in combination with an objective optical system capable of magnifying observation (the objective optical system of the present invention). In these figures, (A) is an optical system including one positive lens, (B) is an optical system including two positive lenses, (C) is an optical system including a negative lens and a positive lens from the object side, and (D) ) Is an optical system composed of three positive lenses.

(A), (B), (C), (D) of FIG.
Each of the illumination optical systems includes at least one positive lens, and can have a smaller outer diameter than an optical system including one negative lens as shown in FIG. It is desirable that the lens closest to the light guide is a positive lens as shown in FIG. As described above, the illumination optical system including at least one positive lens whose light guide lens is the most positive lens can reduce the lens outer diameter by converging the light beam emitted from the light guide by the positive lens. It is.

FIG. 40E shows an illumination optical system having a configuration in which a large number of small-diameter spherical lenses are arranged in front of the light guide. The illumination optical system has a small outer diameter and a very short overall length.

Although the illumination optical system shown in FIGS. 40A to 40E is assumed to have a circular outer diameter, the illumination optical system may have an irregular shape such as an oval shape or a square shape. Thus, the outer diameter of the distal end of the endoscope can be further reduced and downsized.

By combining the objective optical system of the present invention shown in the above-described embodiment with any one of the illumination optical systems shown in FIGS. An endoscope device can be configured.

In the objective optical system according to the present invention, the following optical systems can achieve the object in addition to the optical system described in the claims.

(1) At least one of the plurality of groups moves on the optical axis to perform a zooming operation, and the object distance at the telephoto end is shorter than the object distance at the wide-angle end, and the refractive index of the lens medium An objective optical system comprising at least one gradient index lens having a distribution.

(2) An objective optical system according to the above item (1), wherein the following condition (1) is satisfied. (1) 0.1 <| 1 / {f ₂ (D _W −D _T )} | <2

(3) The objective optical system described in the above item (1) or (2), wherein the following condition (2) is satisfied. (2) 1 <| (f W · f T) 1/2 / f 1 | <2

(4) The objective optical system described in the above item (1), (2) or (3), wherein the following condition (3) is satisfied. (3) 0 <H _u / H _s <0.8

(5) The optical system according to claim 1 or (2), (3) or (4), wherein
An objective optical system which satisfies the following condition (1-1) instead of the condition (1). (1-1) 0.15 <| 1 / {f ₂ (D _W −D _T )} | <1

(6) The optical system according to claim 1 or (3), wherein the following condition (2-1) is satisfied instead of the condition (2). Objective optics. (2-1) 1.1 <| (f W · f T) 1/2 / f 1 | <1.8

(7) The optical system according to claim 2 or (4), wherein the following condition (3-1) is satisfied instead of the condition (3). Objective optics. (3-1) 0.1 <H _u / H _s <0.5

(8) Claims 1 or 2 of the claims or the above (1), (2), (3), (4),
(5) The objective optical system according to (6) or (7), wherein the object distance at the telephoto end is shorter than the object distance at the wide angle end.

(9) Claims 1 or 2 of the claims or the above (1), (2), (3), (4),
(5) The optical system described in (6), (7) or (8), wherein the objective optical system satisfies the following condition (4). (4) 0.1 <d _0T / f _T <5

(10) The objective optical system described in the above item (9), wherein the following condition (4-1) is satisfied instead of the condition (4). (4-1) 0.2 <d _0T / f _T <3

(11) The objective optical system described in the above item (9), wherein the following condition (4-2) is satisfied instead of the condition (4). (4-2) 0.5 <d _0T / f _T <1.5

(12) Claim 1 or 2 of the claims
Alternatively, the above (1), (2), (3), (4),
(5), (6), (7), (8), (9), (10) or (11), and at least one objective optical system.
And an illumination optical system including a number of positive lenses.

(13) The endoscope apparatus according to (12), wherein the illumination optical system has a positive refractive power.

(14) In order from the object side, there are a first group having a positive refractive power, a second group having a negative refractive power, and a third group having a positive refractive power. The first group is composed of one negative lens and at least one positive lens, and the third group is composed of one negative lens and at least one positive lens. An objective optical system, characterized in that:

(15) In order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power are arranged. Characterized in that the objective optical system is movable, and has only one set of cemented lenses.

(16) In order from the object side, there are a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. Wherein the first group is composed of a negative lens, a parallel plate, at least one optical element, and a brightness stop in this order from the object side, and an optical element disposed between the parallel plate and the brightness stop At least one of the objective optical systems satisfies the following condition (5): (5) DDi <0.2mm

(17) In order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power are arranged. Can be moved, and the angle of view is 1
An objective optical system characterized by being at least 20 °.

(18) In order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power are arranged. Characterized by satisfying the following condition (4-3): (4-3) 0.75 <d _OT / f _T <1.5

(18) In order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power are arranged. An objective optical system characterized by having a flare stop on the object side of the third group and satisfying the following condition (7). (7) 0.1 mm <φ3-φFS <1.2 mm

(20) The above (14), (15), (1)
(6) The optical system described in (17), (18) or (19), wherein the objective optical system satisfies the following condition (6). (6) 1 <| β _2W |

[0148]

According to the present invention, it is possible to realize an objective optical system having a short overall length and a small outer diameter of a lens, while enabling magnification observation. Further, when the objective optical system of the present invention is used for an endoscope, an endoscope having a small distal end with a small diameter can be configured in combination with a small illumination optical system.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a seventh embodiment of the present invention.

FIG. 8 is a sectional view of Embodiment 8 of the present invention.

FIG. 9 is a sectional view of Embodiment 9 of the present invention.

FIG. 10 is a sectional view of Embodiment 10 of the present invention.

FIG. 11 is a sectional view of an eleventh embodiment of the present invention.

FIG. 12 is a sectional view of Embodiment 12 of the present invention.

FIG. 13 is an aberration curve diagram at a wide angle end according to the first embodiment of the present invention.

FIG. 14 is an aberration curve diagram at a telephoto end according to the first embodiment of the present invention.

FIG. 15 is an aberration curve diagram at a wide-angle end according to a second embodiment of the present invention.

FIG. 16 is an aberration curve diagram at a telephoto end according to a second embodiment of the present invention.

FIG. 17 is an aberration curve diagram at a wide angle end according to a third embodiment of the present invention.

FIG. 18 is an aberration curve diagram at a telephoto end according to a third embodiment of the present invention.

FIG. 19 is an aberration curve diagram at a wide-angle end according to a fourth embodiment of the present invention.

FIG. 20 is an aberration curve diagram at a telephoto end according to a fourth embodiment of the present invention.

FIG. 21 is an aberration curve diagram at a wide-angle end according to a fifth embodiment of the present invention.

FIG. 22 is an aberration curve diagram at a telephoto end according to a fifth embodiment of the present invention.

FIG. 23 is an aberration curve diagram at a wide-angle end according to a sixth embodiment of the present invention.

FIG. 24 is an aberration curve diagram at a telephoto end according to a sixth embodiment of the present invention.

FIG. 25 is an aberration curve diagram at a wide angle end according to a seventh embodiment of the present invention.

FIG. 26 is an aberration curve diagram at a telephoto end according to a seventh embodiment of the present invention.

FIG. 27 is an aberration curve diagram at a wide-angle end according to an eighth embodiment of the present invention.

FIG. 28 is an aberration curve diagram at a telephoto end according to an eighth embodiment of the present invention.

FIG. 29 is an aberration curve diagram at a wide angle end according to a ninth embodiment of the present invention.

FIG. 30 is an aberration curve diagram at a telephoto end according to a ninth embodiment of the present invention.

FIG. 31 is an aberration curve diagram at a wide-angle end according to a tenth embodiment of the present invention.

FIG. 32 is an aberration curve diagram at a telephoto end according to a tenth embodiment of the present invention.

FIG. 33 is an aberration curve diagram at a wide angle end according to Example 11 of the present invention.

FIG. 34 is an aberration curve diagram at a telephoto end in Example 11 of the present invention.

FIG. 35 is an aberration curve diagram at a wide angle end according to a twelfth embodiment of the present invention.

FIG. 36 is an aberration curve diagram at a telephoto end according to a twelfth embodiment of the present invention.

FIG. 37 is a diagram showing an outline of a configuration of an endoscope distal end portion;

FIG. 38 is a diagram showing an example of an endoscope illumination optical system.

FIG. 39 is a diagram illustrating an outline of a lens arrangement of a first group having a fifth configuration according to the present invention;

FIG. 40 is a sectional view showing an example of an endoscope illumination optical system used in the present invention.

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[Procedure amendment]

[Submission date] March 8, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0059

[Correction method] Change

[Correction contents]

Example 8 f = 1.83 to 2.13, F / 8.9 to 12.3, 2ω = 131 ° to 75.3 ° Object distance = 14.4 to 2.0, Image height = 1.61 r ₁ = ∞ d ₁ = 0.3800 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 1.0600 d ₂ = 0.7200 r ₃ = ∞ d ₃ = 0.4000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.6200 n ₃ = 1.51400 ν ₃ = 75.00 r ₆ = ∞ d ₆ = 0.0500 r ₇ = 3.1860 d ₇ = 1.5100 n ₄ = 1.72916 ν ₄ = 54.68 r ₈ = -2.3660 d ₈ = 0.0500 r ₉ = ∞ (aperture) d ₉ = D ₁ (variable) r _{10 = ∞ d 10 = 0.2800 n 5} = 1.59551 ν 5 = 39.24 r 11 = 2.9200 d 11 = 0.1800 r 12 = ∞ d 12 = D 2 ( _{variable) r 13 = ∞ d 13 =} -0.0800 r 14 = 4.2960 d 14 = _{1.8000 n 6 = 1.72916 ν 6 =} 54.68 r 15 = -2.0850 d 15 = 0.3200 n 7 = 1.84666 ν 7 = 23.78 r 16 = -5.8750 d 16 = 2.0900 r 17 = ∞ d 17 = 1.2000 n 8 = 1.51633 ν 8 = 64.14 r ₁₈ = ∞ d ₁₈ = 0.0100 n ₉ = 1.5 6384 ν ₉ = 60.67 r ₁₉ = ∞ d ₁₉ = 1.2000 n ₁₀ = 1.53172 ν ₁₀ = 48.84 r ₂₀ = ∞ d ₂₀ = 0.0300 n ₁₁ = 1.56384 ν ₁₁ = 60.67 r ₂₁ = ∞ f 1.83 2.13 D ₀ 14.40000 2.00000 D _{1 0.20000 2.09000 D 2 2.2000 0.31000 | 1} / {f 2 (D W -D T)} | = 0.11 | (f W · f T) 1/2 / f 1 | = 0.89, H u / H s = 0.36, d _0T / f _T = 0.94 β _2W = 8.30, φ3-φFS = 0.6mm

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0060

[Correction method] Change

[Correction contents]

Example 9 f = 1.97 to 2.52, F / 9.2 to 15.6, 2ω = 129.9 ° to 56.3 ° Object distance = 15 to 2.0, Image height = 1.61 r ₁ = ∞ d ₁ = 0.4000 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 1.0945 d ₂ = 0.8692 r ₃ = ∞ d ₃ = 0.4000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.6200 n ₃ = 1.51400 ν ₃ = 75.00 r ₆ = ∞ d ₆ = 0.1000 r ₇ = 2.1389 d ₇ = 0.5000 n ₄ = 1.88300 ν ₄ = 40.76 r ₈ = 1.0592 d ₈ = 1.4605 n ₅ = 1.63930 ν ₅ = 44.87 r ₉ = -2.1142 d ₉ = 0.1000 r ₁₀ = ∞ (aperture) d ₁₀ = D ₁ (variable) r ₁₁ = -59.6121 d ₁₁ = 0.3000 n ₆ = 1.88300 ν ₆ = 40.76 r ₁₂ = 3.8932 d ₁₂ = D ₂ (variable) r ₁₃ = 4.3415 d ₁₃ = 1.5693 n ₇ = 1.77250 ν ₇ = 49.60 r ₁₄ = -2.1637 d ₁₄ = 0.2810 n ₈ = 1.90135 ν ₈ = 31.55 r ₁₅ = -7.3937 d ₁₅ = 3.4307 r ₁₆ = ∞ d ₁₆ = 1.5000 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₇ = ∞ d ₁₇ = 1.2500 n ₁₀ = 1.51633 ν ₁₀ = 64.14 r ₁₈ = ∞ f 1.97 2.52 D ₀ 15.00000 2.00000 D ₁ 0.20000 2.69967 D ₂ 2.74757 0.25000 | 1 / {f ₂ (D _W -D _T )} | = 0. 10 | (f _W・ f _T ) ^1/2 / f ₁ | = 0.95, H _u / H _s = 0.11, d _0T / f _T = 0.79, β _2W = 2.1

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0061

[Correction method] Change

[Correction contents]

Example 10 f = 1.14 to 1.53, F / 7.3 to 12, 2ω = 132.9 ° to 65.3 ° Object distance = 12 to 2.2, Image height = 1.05 r ₁ = ∞ d ₁ = 0.2600 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.7216 d ₂ = 0.4587 r ₃ = ∞ d ₃ = 0.4000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.6200 n ₃ = 1.51400 ν ₃ = 75.00 r ₆ = ∞ d ₆ = 0.0400 r ₇ = 3.6037 d ₇ = 0.6175 n ₄ = 1.88300 ν ₄ = 40.76 r ₈ = -1.8142 d ₈ = 0.0500 r ₉ = ∞ (aperture) d ₉ = D ₁ (variable) r ₁₀ = -8.7484 d ₁₀ = 0.2000 n ₅ = 1.90135 ν ₅ = 31.55 r ₁₁ = 2.5880 d ₁₁ = D ₂ (variable) r ₁₂ = ∞d ₁₂ = 0.0000 r ₁₃ = 3.6204 d ₁₃ = 0.6208 n ₆ = 1.88300 ν ₆ = 40.76 r ₁₄ = -3.7375 d ₁₄ = 0.0500 r ₁₅ = 4.4029 d ₁₅ = 0.8061 n ₇ = 1.51633 ν ₇ = 64.14 r ₁₆ = -1.6972 d ₁₆ = 0.2000 n ₈ = 1.84666 ν ₈ = 23.78 r ₁₇ = 39.0105 d ₁₇ = 1.2038 r ₁₈ = ∞ d ₁₈ = 1.1000 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₉ = ∞ d ₁₉ = 0.8000 n ₁₀ = 1.51633 ν ₁₀ = 64.14 r ₂₀ = ∞ f 1.14 1.53 D ₀ 12.00000 2.20000 D ₁ 0.15000 1.32311 D ₂ 1.32311 0.15000 | 1 / {f ₂ (D _W -D _T )} | = 0.39 | (f _W · f _T ) ^1/2 / f ₁ | = 0.90, _Hu / H _s = 0.44, d _0T / f _T = 1.44 β _2W = 1.36, φ3-φFS = 0.4mm

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction contents]

Example 11 f = 1.35 to 2.04, F / 6.4 to 11.7, 2ω = 130 ° to 56.6 ° Object distance = 12 to 2.1, Image height = 1.21 r ₁ = ∞ d ₁ = 0.3000 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.7564 d ₂ = 0.5000 r ₃ = ∞ d ₃ = 0.4000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0300 r ₅ = ∞ d ₅ = 0.6200 n ₃ = 1.51400 ν ₃ = 75.00 r ₆ = ∞ d ₆ = 0.0500 r ₇ = 16.9172 d ₇ = 0.6000 n ₄ = 1.51633 ν ₄ = 64.14 r ₈ = -1.5139 d ₈ = 0.0500 r ₉ = 5.5489 d ₉ = 0.5000 n ₅ = 1.51633 ν ₅ = 64.14 r _{10 = -2.7205 d 10 = 0.5000 r} 10 = ∞ ( stop) d ₁₁ = D _{1 (variable) r 12 = -6.2390 d 12 =} 0.2500 n 6 = 1.88300 ν 6 = 40.76 r 13 = 2.6147 d 13 = D 2 ( (Variable) r ₁₄ = 6.1306 d ₁₄ = 1.1000 n ₇ = 1.72916 ν ₇ = 54.68 r ₁₅ = -1.5473 d ₁₅ = 0.2500 n ₈ = 1.84666 ν ₈ = 23.78 r ₁₆ = -3.6654 d ₁₆ = 0.0500 r ₁₇ = 6.0286 d ₁₇ = 0.6288 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₈ = ∞ d ₁₈ = 2.9631 r ₁₉ = ∞ d ₁₉ = 1.5000 n ₁₀ = 1.51633 ν ₁₀ = 64.14 r ₂₀ = ∞ d ₂₀ = 1.0000 n ₁₁ = 1.51633 ν ₁₁ = 64.14 r ₂₁ = ∞ f 1.35 2.04 D ₀ 12.00000 2.10000 D ₁ 0.20000 1.54000 D ₂ 1.59000 0.25000 | 1 / {f ₂ (D _W -D _T )} | = 0.36 | (f _W · f _T ) ^1/2 / f ₁ | = 1.17, H _u / H _s = 0.52, d _0T / f _T = 1.03, β _2W = 1.14

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction contents]

Example 12 f = 1.21 to 1.48, F / 6.8 to 9.7, 2ω = 149.6 ° to 76.3 ° Object distance = 12 to 1.9, Image height = 1.1 r ₁ = ∞ d ₁ = 0.2500 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.7403 d ₂ = 0.4194 r ₃ = ∞ d ₃ = 0.2000 n ₂ = 1.52287 ν ₂ = 59.89 r ₄ = ∞ d ₄ = 0.0500 r ₅ = 2.1275 d ₅ = 1.7387 n ₃ = 1.68893 ν ₃ = 31.07 r ₆ = -1.3323 d ₆ = 0.0500 r ₇ = ∞ (aperture) d ₇ = D ₁ (variable) r ₈ = 282.6298 d ₈ = 0.2000 n ₄ = 1.84666 ν ₄ = 23.78 r ₉ = 2.6319 d ₉ = D ₂ ( (Variable) r ₁₀ = 4.5636 d ₁₀ = 0.8674 n ₅ = 188300 ν ₅ = 40.76 r ₁₁ = -1.7560 d ₁₁ = 0.2000 n ₆ = 1.84666 ν ₆ = 23.78 r ₁₂ = -4.2149 d ₁₂ = 0.1000 r ₁₃ = ∞d ₁₃ = 0.6200 n ₇ = 1.51400 ν ₇ = 75.00 r ₁₄ = ∞ d ₁₄ = 1.2120 r ₁₅ = ∞ d ₁₅ = 1.0000 n ₈ = 1.51633 ν ₈ = 64.14 r ₁₆ = ∞ d ₁₆ = 0.5000 n ₉ = 1.51633 ν ₉ = 64.14 r ₁₇ = ∞ f 1.21 1.48 D ₀ 12.00000 1.90000 D ₁ 0.10000 1.35581 D ₂ 1.40581 0.15000 | 1 / {f ₂ (D _W -D _T )} | = 0.25 | (f _W · f _T ) ^1/2 / f ₁ | = 0.79, H _u / H _s = 0.45, d _0T / f _T = 1.28, β _2W = 3.63 where r ₁ , r ₂ ,... are the radii of curvature of the respective surfaces of the lens, d
_.. , D ₂ ,...
₁ , n ₂ ,... Are the refractive indices of each lens, ν ₁ , ν ₂ ,.
Is the Abbe number of each lens. D ₀ is the object distance.
The unit of the length in the data is mm.

Claims (2)

[Claims] 1. A first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. The second lens unit moves on the optical axis. An objective optical system which performs a zooming operation by satisfying the following conditions (1) and (2). (1) 0.1 <| 1 / {f ₂ (D _W −D _T )} | <2 (2) 1 <| (f _W · f _T ) ^1/2 / f ₁ | <2 where f ₁ , F ₂ are the focal lengths of the first and second lens units, respectively, and D _W and D _T are the first and second lens units at the wide-angle end and the telephoto end, respectively.
Group and spacing of the second group, f _W, is f _T is a focal length of the entire system at the wide-angle end and the telephoto end. 2. An objective optical system comprising a plurality of groups and a brightness stop, wherein at least one group performs a zooming operation by moving on an optical axis, and satisfies the following condition (3). system. _{(3) 0 <H u /} H s <0.8 , however, off-axis upper ray height in H _u is the aperture stop position, H _s is the radius of the aperture stop.