Observation optical system, optical apparatus, and method for manufacturing observation optical system

Abstract

To solve the problem, in an observation optical system, that it is desired to provide an observation optical system capable of more satisfactorily correcting various aberrations and having small size, light weight, a wide field of view, a high magnification and a large aperture.SOLUTION: An observation optical system includes, in order from an object side, an objective optical system, an erecting optical system, and an eyepiece optical system, where the erecting optical system is a relay optical system, a first intermediate image is formed between the objective optical system and the relay optical system, a second intermediate image is formed between the relay optical system and the eyepiece optical system, and the following conditional expressions are satisfied: 0.060<fe / TL<0.130, where fe is focal length of the eyepiece optical system, and TL is total optical length of an observation optical system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an observation optical system, an optical instrument, and a method for manufacturing an optical system. [Background technology]

[0002] Conventionally, among observation optical systems whose main purpose is to observe an object, there are known those that use an erecting prism as an erecting optical system, as in Patent Document 1. In recent years, there has been a demand for such observation optical systems that can correct various aberrations more effectively, and that are small, lightweight, have a wide field of view, have a high magnification, and a large aperture. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-40065 Summary of the Invention

[0004] An observation optical system according to a first aspect has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, wherein the erecting optical system is a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system, and forms a second intermediate image between the relay optical system and the eyepiece optical system, and the observation optical system satisfies the following conditional expressions: 0.060 <fe / TL<0.130 however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

[0005] An observation optical system according to a second aspect has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, wherein the erecting optical system is a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system, and a second intermediate image between the relay optical system and the eyepiece optical system, and further comprises a second observation optical system that is composed of the same lens components as the first observation optical system, and the first observation optical system and the second observation optical system are arranged in parallel.

[0006] An observation optical system according to a third aspect has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, wherein the erecting optical system is a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system, and forms a second intermediate image between the relay optical system and the eyepiece optical system, and the observation optical system satisfies the following conditional expressions: 0.040 <Dm / TL<0.350 however, Dm: the maximum air gap between lens surfaces in the observation optical system TL: total optical length of the observation optical system

[0007] An observation optical system according to a fourth aspect has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, wherein the erecting optical system is a relay optical system, which forms a first intermediate image between the objective optical system and the relay optical system, and forms a second intermediate image between the relay optical system and the eyepiece optical system, and at least one lens S of the lenses arranged in the objective optical system satisfies the following conditional expression: 80.00<νds however, νds: Abbe number of the lens S for the d line

[0008] An optical apparatus according to a fifth aspect includes the above observation optical system.

[0009] A sixth aspect of the manufacturing method for an observation optical system includes, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system, and a second intermediate image between the relay optical system and the eyepiece optical system, and is configured to satisfy the following conditional expressions: 0.060 <fe / TL<0.130 however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

[0010] In addition, a manufacturing method for an observation optical system according to a seventh aspect includes a first observation optical system having, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, wherein the erecting optical system is a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system and a second intermediate image between the relay optical system and the eyepiece optical system, and further includes a second observation optical system that is composed of the same lens components as the first observation optical system, and the first observation optical system and the second observation optical system are arranged in parallel.

[0011] Furthermore, a manufacturing method for an observation optical system according to an eighth aspect includes, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system, and a second intermediate image between the relay optical system and the eyepiece optical system, and is configured to satisfy the following conditional expressions: 0.040 <Dm / TL<0.350 however, Dm: the maximum air gap between lens surfaces in the observation optical system TL: total optical length of the observation optical system

[0012] Furthermore, a manufacturing method for an observation optical system according to a ninth aspect includes, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system that forms a first intermediate image between the objective optical system and the relay optical system, and a second intermediate image between the relay optical system and the eyepiece optical system, and at least one lens S of the lenses arranged in the objective optical system is configured to satisfy the following conditional expression: 80.00<νds however, νds: Abbe number of the lens S for the d line [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view of the observation optical system according to the first example. [Figure 2] 5A to 5C are diagrams showing various aberrations of the observation optical system according to Example 1. [Figure 3] FIG. 10 is a cross-sectional view of an observation optical system according to a second example. [Figure 4] 10A to 10C are diagrams showing various aberrations of the observation optical system according to Example 2. [Figure 5] FIG. 10 is a cross-sectional view of an observation optical system according to a third example. [Figure 6] 10A to 10C are diagrams showing various aberrations of the observation optical system according to Example 3. [Figure 7] FIG. 10 is a cross-sectional view of an observation optical system according to a fourth example. [Figure 8] 10A to 10C are diagrams showing various aberrations of the observation optical system according to Example 4. [Figure 9] FIG. 10 is a cross-sectional view of an observation optical system according to a fifth example. [Figure 10] 10A to 10C are diagrams showing various aberrations of the observation optical system according to Example 5. [Figure 11] FIG. 13 is a cross-sectional view of an observation optical system according to Example 6. [Figure 12] 13A to 13C are diagrams illustrating various aberrations in the observation optical system according to Example 6. [Figure 13] FIG. 13 is a cross-sectional view of an observation optical system according to a seventh example. [Figure 14] 13A to 13C are diagrams illustrating various aberrations in the observation optical system according to Example 7. [Figure 15] FIG. 13 is a cross-sectional view of an observation optical system according to an eighth example. [Figure 16] 13A to 13C are diagrams illustrating various aberrations in the observation optical system according to Example 8. [Figure 17] FIG. 13 is a cross-sectional view of an observation optical system according to a ninth example. [Figure 18] 13A to 13C are diagrams illustrating various aberrations in the observation optical system according to Example 9. [Figure 19] FIG. 23 is a cross-sectional view of an observation optical system according to a tenth example. [Figure 20] 16A to 16C are diagrams illustrating various aberrations in the observation optical system according to Example 10. [Figure 21] FIG. 10 is a cross-sectional view of an observation optical system according to a second embodiment, which uses a pair of observation optical systems. [Figure 22] 1 is a schematic cross-sectional view of binoculars, which is an optical instrument that uses a pair of observation optical systems. [Figure 23] FIG. 2 is a flowchart showing an outline of a method for manufacturing the optical devices according to the first and third embodiments. [Figure 24] FIG. 10 is a flowchart showing an outline of a method for manufacturing an optical device according to a second embodiment. [Figure 25] FIG. 10 is a flowchart showing an outline of a method for manufacturing an optical device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Below, we will explain the observation optical system, optical device, and optical system manufacturing method according to the basic embodiment and first to fourth embodiments of the present application. However, the present invention is not limited to the following embodiments, and any combination may be used. Furthermore, to avoid complication of explanation due to an increase in the number of reference symbols, the reference symbols for the figures according to each embodiment may be used independently in each drawing. Therefore, even if reference symbols common to other drawings are used, they do not necessarily have the same configuration as those in the other drawings.

[0015] First, the observation optical system according to this basic embodiment will be described. The observation optical system OS according to this basic embodiment has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, which forms a first intermediate image I1 between the objective optical system O and the relay optical system R, and a second intermediate image I2 between the relay optical system R and the eyepiece optical system E.

[0016] The objective optical system O has positive refractive power and, for example, collects light from a distant object to form a first intermediate image I1, which is an inverted image. The relay optical system R has positive refractive power and re-images the first intermediate image I1, which is an inverted image formed by the objective optical system O, to form a second intermediate image I2, which is an erect image. The eyepiece optical system E has positive refractive power and magnifies the second intermediate image I2, which is an erect image formed by the relay optical system R. By configuring the observation optical system OS in this way, an observer (not shown) can observe the object to be observed at eyepoint EP. Note that the observation optical system OS allows the spacing between some of the lenses to be changed to adjust the diopter. By forming the erecting optical system using a relay optical system R, the first intermediate image I1 formed by the objective optical system O can be appropriately reduced, magnified to the same magnification, enlarged, or variable, compared to an erecting prism, and various aberrations occurring in the objective optical system O and the eyepiece optical system E can be effectively corrected. Image blur can also be corrected by shifting or rotating some of the lenses about the optical axis. Furthermore, the diameter of the erecting optical system can be made smaller than with an erecting prism. This allows the observation optical system OS to achieve high magnification while maintaining a wide real field of view, and also allows for a smaller, lighter size. This observation optical system OS may have a focusing screen disposed on the image plane of at least one (or both) of the first intermediate image I1 and the second intermediate image I2, which serves as a collimation system. The focusing screen is typically a crosshair and field ring formed on a glass plate with chrome deposition, but a display component such as an LCD panel may be used to realize a variable display, or various types of information may be displayed as appropriate. With this configuration, the observation optical system OS of this basic embodiment can effectively correct various aberrations, particularly spherical aberration, astigmatism, field curvature, chromatic aberration (i.e., axial chromatic aberration, lateral chromatic aberration), and the like, thereby achieving high magnification and compact, lightweight design while maintaining a wide actual field of view.

[0017] With this configuration, the viewing optical system of the first embodiment further satisfies the following conditional expression (1). 0.060 <fe / TL<0.130 (1) however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

[0018] The conditional expression (1) defines the ratio between the focal length of the eyepiece optical system and the overall optical length of the observation optical system. By satisfying conditional expression (1), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be corrected well, and high magnification can be achieved while maintaining a wide actual field of view. In particular, spherical aberration and coma can be corrected well while maintaining a compact and lightweight lens.

[0019] Note that the effect of the first embodiment can be more reliably achieved by setting the lower limit of conditional expression (1) to 0.062. In order to further ensure the effect of the first embodiment, it is more preferable to set the lower limit of conditional expression (1) to 0.064, 0.066, 0.067, or even 0.068. On the other hand, by setting the upper limit of conditional expression (1) to 0.125, the effect of the first embodiment can be more reliably achieved. Furthermore, in order to further ensure the effect of the first embodiment, it is more preferable to set the upper limit of conditional expression (1) to 0.120, 0.115, 0.110, 0.105, 0.100, or even 0.097.

[0020] The observation optical system OS of the second embodiment is the same as that of the basic embodiment, i.e., a first observation optical system OS1 having, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, which forms a first intermediate image I1 between the objective optical system O and the relay optical system R, and a second intermediate image I2 between the relay optical system R and the eyepiece optical system E. With this configuration, the observation optical system OS further has a second observation optical system OS2 which is composed of the same lens components as the first observation optical system OS1, and the first observation optical system OS1 and the second observation optical system OS2 are arranged in parallel.

[0021] With this configuration, the observation optical system OS of the second embodiment has the same effects as the configuration of the observation optical system OS of the basic embodiment, and further, the first observation optical system OS1 and the second observation optical system OS2 are constructed using the same lens components, allowing binocular observation with the same optical performance. For the first observation optical system OS1 and the second observation optical system OS2, the spacing between some of the lenses can be changed differently relative to the other to adjust the diopter. The same lens components are lenses having the same radius of curvature, thickness, and material of the surface, but may have different anti-reflection coatings, outer shapes, etc. At least one of the first observation optical system OS1 and the second observation optical system OS2 may use optical components (such as the focusing screen, display component, optical filter, prism, etc.), or different optical components may be used.

[0022] Furthermore, the observation optical system OS of this third embodiment is the same as that of the basic embodiment, i.e., it has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, which forms a first intermediate image I1 between the objective optical system O and the relay optical system R, and a second intermediate image I2 between the relay optical system R and the eyepiece optical system E. With this configuration, the observation optical system OS of the third embodiment has the same effect as the configuration of the observation optical system OS of the basic embodiment, and with this configuration, the following conditional expression is further satisfied. 0.040 <Dm / TL<0.350 (2) however, Dm: the maximum air gap between lens surfaces in the observation optical system TL: total optical length of the observation optical system

[0023] Conditional expression (2) defines the ratio of the maximum air gap between lens surfaces in the observation optical system to the total optical length of the observation optical system. By satisfying conditional expression (2), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be corrected effectively, a high magnification can be achieved while maintaining a wide actual field of view, and a compact, lightweight lens can be achieved. In particular, spherical aberration and coma can be corrected well at high magnification while maintaining a small and lightweight design. It should be noted that the above Dm is the air-equivalent length when an optical component with no refractive power, such as a prism, is present between the lens surfaces.

[0024] It should be noted that the effect of the third embodiment can be more reliably achieved by setting the lower limit of conditional expression (2) to 0.045. Furthermore, in order to more reliably achieve the effect of the third embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.050, 0.055, 0.060, 0.065, 0.070, 0.075, or even 0.078. On the other hand, by setting the upper limit of conditional expression (2) to 0.330, the effect of the third embodiment can be more reliably achieved. Furthermore, in order to further ensure the effect of the third embodiment, it is more preferable to set the upper limit of conditional expression (2) to 0.300, 0.280, 0.250, 0.230, 0.200, 0.180, 0.150, 0.130, or even 0.100.

[0025] The observation optical system OS of the fourth embodiment is the same as that of the basic embodiment, i.e., it has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, which forms a first intermediate image I1 between the objective optical system O and the relay optical system R, and a second intermediate image I2 between the relay optical system R and the eyepiece optical system E. With this configuration, the observation optical system OS of the fourth embodiment has the same effects as the configuration of the observation optical system OS of the basic embodiment, and with this configuration, at least one lens S of the lenses arranged in the objective optical system satisfies the following conditional expression: 80.00<νds (3) however, νds: Abbe number of the lens S for the d line

[0026] Here, the Abbe number ν for the d-line is expressed by the following equation, where the refractive index for the C-line (wavelength 656.3 nm) is nC, the refractive index for the d-line (wavelength 587.6 nm) is nd, and the refractive index for the F-line (wavelength 486.1 nm) is nF. ν=(nd-1) / (nF-nC) The formula for the Abbe number for the d-line is the same for the subsequent conditional expressions, and the explanation will be omitted.

[0027] Conditional expression (3) defines the Abbe number of the lens S with respect to the d-line. By satisfying conditional expression (3), various aberrations, such as chromatic aberrations, i.e., axial chromatic aberration, lateral chromatic aberration, spherical aberration, astigmatism, curvature of field, etc., can be corrected well, and a high magnification can be achieved while maintaining a wide actual field of view, and a compact, lightweight lens can also be achieved. In particular, axial chromatic aberration and lateral chromatic aberration can be corrected well.

[0028] Note that the effect of the fourth embodiment can be more reliably achieved by setting the lower limit of conditional expression (3) to 81.00. To further ensure the effect of the fourth embodiment, it is more preferable to set the lower limit of conditional expression (3) to 82.00, 84.00, 86.00, 88.00, 90.00, 92.00, or even 93.00. Note that the effect of the fourth embodiment can be further ensured by setting the upper limit of conditional expression (3) to "<100.00." In order to further ensure the effect of the fourth embodiment, it is more preferable to set the upper limit of conditional expression (3) to 98.00, 96.00, 94.00, 92.00, 90.00, 88.00, 86.00, or even 84.00.

[0029] Here, it is preferable to satisfy conditional expressions (1) to (3) in combination, since a combined effect can be obtained. In the observation optical systems according to the first to fourth embodiments, it is desirable that at least one lens S among the lenses arranged in the objective optical system satisfies the following conditional expression. however, 1.4300 <nds<1.5200 (4) however, nds: refractive index of the lens S at the d line

[0030] Conditional expression (4) defines the refractive index of the lens S with respect to the d-line. By satisfying conditional expression (4), various aberrations, such as spherical aberration, coma, chromatic aberration (i.e., axial chromatic aberration, lateral chromatic aberration), can be effectively corrected, and a high magnification can be achieved while maintaining a wide field of view, and a compact, lightweight lens can be achieved. In particular, spherical aberration, coma, axial chromatic aberration, and lateral chromatic aberration can be effectively corrected.

[0031] Note that by setting the lower limit of conditional expression (4) to 1.4320, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (4) to 1.4370, 1.4400, 1.4500, 1.4600, 1.4700, or even 1.4800. On the other hand, by setting the upper limit of conditional expression (4) to 1.5100, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (4) to 1.5000, 1.4900, 1.4800, 1.4700, or even 1.4600.

[0032] Furthermore, in the observation optical systems according to the first to fourth embodiments, it is desirable that at least one lens S among the lenses arranged in the objective optical system is the positive lens closest to the object among the positive lenses included in the objective optical system.

[0033] This configuration makes it possible to effectively correct various aberrations, such as spherical aberration, coma, chromatic aberration (i.e., axial chromatic aberration, lateral chromatic aberration), achieve high magnification while maintaining a wide field of view, and achieve a compact and lightweight design. In particular, spherical aberration, coma, axial chromatic aberration, and lateral chromatic aberration can be effectively corrected.

[0034] In addition, in the observation optical systems according to the first to fourth embodiments, it is desirable that the lens closest to the object side of the observation optical system is a negative lens.

[0035] With this type of configuration, various aberrations, particularly spherical aberration, coma, chromatic aberration (i.e., axial chromatic aberration, lateral chromatic aberration), etc., can be effectively corrected, the lens is durable, achieves high magnification while maintaining a wide actual field of view, and is also compact and lightweight.

[0036] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 4.00<(-fcom) / fe<30.00 (5) however, fcom: the combined focal length of the objective optical system and the relay optical system fe: focal length of the eyepiece optical system

[0037] Condition (5) defines the ratio of the combined focal length of the objective optical system and the relay optical system to the focal length of the eyepiece optical system, and indicates the magnification of the viewing optical system.

[0038] By satisfying conditional expression (5), various aberrations, particularly spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), lateral chromatic aberration, etc., can be corrected well, a high magnification can be achieved while maintaining a wide actual field of view, and a compact, lightweight lens can be achieved.

[0039] It should be noted that by setting the lower limit of conditional expression (5) to 4.50, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (5) to 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50, 9.00, or even 9.50. On the other hand, by setting the upper limit of conditional expression (5) to 25.00, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (5) to 20.00, 18.00, 16.00, 14.00, 12.00, 11.00, 10.60, or even 10.30.

[0040] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 4.00 <tanθ' / tanθ<30.00 (6) however, 2θ: actual field of view of the observation optical system, unit [°] 2θ': apparent field of view of the observation optical system, unit [°]

[0041] Condition (6) defines the ratio between the actual field of view of the observation optical system and the apparent field of view of the observation optical system, and indicates the magnification of the observation optical system.

[0042] By satisfying conditional expression (6), various aberrations, such as coma, astigmatism, curvature of field, chromatic aberration (i.e., axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact, lightweight lens can be achieved. In particular, coma can be effectively corrected while maintaining a high magnification in a compact, lightweight lens.

[0043] It should be noted that by setting the lower limit of conditional expression (6) to 4.50, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first embodiment, it is more preferable to set the lower limit of conditional expression (6) to 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50, 9.00, or even 9.50. On the other hand, by setting the upper limit of conditional expression (6) to 25.00, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (6) to 20.00, 18.00, 16.00, 14.00, 12.00, 11.00, 10.60, or even 10.30.

[0044] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 1.00<(-fcom) / fo<3.50 (7) however, fcom: the combined focal length of the objective optical system and the relay optical system fo: focal length of the objective optical system

[0045] Condition (7) defines the ratio of the combined focal length of the objective optical system and the relay optical system to the focal length of the objective optical system, and indicates the magnification of the relay optical system.

[0046] By satisfying conditional expression (7), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide actual field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0047] It should be noted that by setting the lower limit of conditional expression (7) to 1.10, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (7) to 1.20, 1.30, 1.40, 1.50, 1.55, 1.60, 1.65, 1.70, or even 1.75. On the other hand, by setting the upper limit of conditional expression (7) to 3.40, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (7) to 3.30, 3.20, 3.10, 3.00, 2.90, or even 2.80.

[0048] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.030 <ER / TL<0.120 (8) however, ER: Eye relief of the observation optical system TL: total optical length of the observation optical system

[0049] Conditional expression (8) defines the ratio between the eye relief of the observation optical system and the total optical length of the observation optical system. By satisfying conditional expression (8), various aberrations, particularly spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), lateral chromatic aberration, etc., can be corrected well, an appropriate eye relief can be obtained, high magnification can be achieved while maintaining a wide actual field of view, and compactness and weight reduction can be achieved.

[0050] It should be noted that by setting the lower limit of conditional expression (8) to 0.040, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (8) to 0.045, 0.050, 0.055, 0.060, 0.065, 0.070, or even 0.072. On the other hand, by setting the upper limit of conditional expression (8) to 0.110, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (8) to 0.105, 0.100, 0.095, 0.090, or even 0.085.

[0051] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 3.00 <fo / fe<8.00 (9) however, fo: focal length of the objective optical system fe: focal length of the eyepiece optical system

[0052] Condition (9) defines the ratio between the focal length of the objective optical system and the focal length of the eyepiece optical system. By satisfying conditional expression (9), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0053] It should be noted that by setting the lower limit of conditional expression (9) to 3.10, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first embodiment, it is more preferable to set the lower limit of conditional expression (9) to 3.20, 3.30, 3.40, 3.50, 3.60, or even 3.70. On the other hand, by setting the upper limit of conditional expression (9) to 7.50, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (9) to 7.00, 6.80, 6.50, 6.30, 6.00, 5.80, 5.60, 5.40, or even 5.20.

[0054] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.030 <fr / TL<0.160 (10) however, fr: focal length of the relay optical system TL: total optical length of the observation optical system

[0055] Condition (10) defines the ratio between the focal length of the relay optical system and the total optical length of the observation optical system. By satisfying condition (10), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0056] It should be noted that by setting the lower limit of conditional expression (10) to 0.032, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (10) to 0.034, 0.036, 0.038, 0.040, 0.046, or even 0.060. On the other hand, by setting the upper limit of conditional expression (10) to 0.150, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (10) to 0.140, 0.130, 0.120, 0.110, 0.100, 0.090, 0.080, or even 0.060.

[0057] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.40<(-fcom) / TL<1.20 (11) however, fcom: the combined focal length of the objective optical system and the relay optical system TL: total optical length of the observation optical system

[0058] Condition (11) defines the ratio of the combined focal length of the objective optical system and the relay optical system to the total optical length of the observation optical system. By satisfying conditional expression (11), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (i.e., axial chromatic aberration, lateral chromatic aberration), etc., can be effectively corrected, a high magnification can be achieved while maintaining a wide actual field of view, and a compact, lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact, lightweight lens.

[0059] Note that by setting the lower limit of conditional expression (11) to 0.45, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (11) to 0.50, 0.55, 0.60, 0.65, or even 0.70. On the other hand, by setting the upper limit of conditional expression (11) to 1.15, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (11) to 1.13, 1.10, 1.08, 1.05, 1.03, 1.00, 0.97, or even 0.90.

[0060] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 2.50 <fo / fr<10.00 (12) however, fo: focal length of the objective optical system fr: focal length of the relay optical system

[0061] Condition (12) is a condition that defines the ratio between the focal length of the objective optical system and the focal length of the relay optical system. By satisfying condition (12), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0062] It should be noted that by setting the lower limit of conditional expression (12) to 2.60, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (12) to 2.80, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, or even 7.00. On the other hand, by setting the upper limit of conditional expression (12) to 9.80, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (12) to 9.60, 9.40, 9.20, 9.00, 8.80, 8.30, or even 8.00.

[0063] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.40 <fr / fe<2.50 (13) however, fr: focal length of the relay optical system fe: focal length of the eyepiece optical system

[0064] Condition (13) defines the ratio between the focal length of the relay optical system and the focal length of the eyepiece optical system. By satisfying condition (13), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide actual field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0065] It should be noted that by setting the lower limit of conditional expression (13) to 0.42, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (13) to 0.44, 0.46, 0.48, 0.50, or even 0.58. On the other hand, by setting the upper limit of conditional expression (13) to 2.30, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (13) to 2.10, 1.80, 1.60, 1.40, 1.20, 1.10, 0.90, or even 0.80.

[0066] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.70 <D1 / TL<1.20 (14) however, D1: From the object side of the lens component arranged second from the object side of the objective optical system Distance to the most observable side of the eyepiece optical system TL: total optical length of the observation optical system

[0067] Conditional formula (14) defines the ratio of the distance from the object-side surface of the second lens component from the object side in the objective optical system to the observation-side surface of the eyepiece optical system to the total optical length of the observation optical system. By satisfying condition (14), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0068] Note that by setting the lower limit of conditional expression (14) to 0.72, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (14) to 0.75, 0.77, 0.80, 0.82, 0.85, 0.87, 0.90, or even 0.91. On the other hand, by setting the upper limit of conditional expression (14) to 1.18, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (14) to 1.15, 1.13, 1.10, 1.08, 1.05, 1.03, 1.00, or even 0.96.

[0069] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.030 <D2 / TL<0.200 (15) however, D2: the distance from the most observation side of the relay optical system to the most object side of the eyepiece optical system TL: total optical length of the observation optical system Condition (15) defines the ratio of the distance from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system to the total optical length of the observation optical system. By satisfying condition (15), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens. It should be noted that D2 is the air distance converted into air length when an optical component with no refractive power, such as a prism, is present between the lens surfaces.

[0070] It should be noted that by setting the lower limit of conditional expression (15) to 0.032, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (15) to 0.034, 0.036, 0.038, 0.040, 0.042, 0.044, or even 0.045. On the other hand, by setting the upper limit of conditional expression (15) to 0.180, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (15) to 0.160, 0.140, 0.120, 0.110, 0.100, 0.095, or even 0.090.

[0071] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.90<(-fe1) / fe<10.00 (16) however, fe1: the focal length of the negative lens in the eyepiece optical system closest to the object fe: focal length of the eyepiece optical system

[0072] Conditional expression (16) defines the ratio between the focal length of the negative lens in the eyepiece optical system that is closest to the object and the focal length of the eyepiece optical system. By satisfying conditional expression (16), various aberrations, particularly spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), lateral chromatic aberration, etc., can be corrected well, a suitable eye relief can be provided, high magnification can be achieved while maintaining a wide actual field of view, and compactness and weight reduction can be achieved.

[0073] Note that by setting the lower limit of conditional expression (16) to 0.95, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (16) to 0.98, 1.20, 1.40, 1.60, 1.80, 2.00, 2.20, 2.50, 2.70, 3.00, 3.50, or even 4.00. On the other hand, by setting the upper limit of conditional expression (16) to 9.00, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (16) to 8.00, 7.00, 6.50, 6.00, 5.70, or even 5.00.

[0074] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 2.00 <rL / fe<200.00 (17) however, rL: Radius of curvature of the lens surface of the eyepiece optical system closest to the observation side fe: focal length of the eyepiece optical system

[0075] Condition (17) defines the ratio between the radius of curvature of the lens surface of the eyepiece optical system that is closest to the observation side and the focal length of the eyepiece optical system. By satisfying condition (17), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0076] Note that by setting the lower limit of conditional expression (17) to 2.20, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (17) to 2.50, 2.70, 3.00, 3.20, 3.50, 3.70, 4.00, or even 4.50. On the other hand, by setting the upper limit of conditional expression (17) to 180.00, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (17) to 160.00, 120.00, 70.00, 50.00, 30.00, 20.00, 18.00, 16.00, 15.00, 12.00, 10.00, 8.00, 7.00, 5.50, or even 5.00.

[0077] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 0.55<Φe / Φ<1.50 (18) however, Φe: maximum effective diameter of the eyepiece optical system Φ: diameter of the objective optical system

[0078] Condition (18) defines the ratio between the maximum effective diameter of the eyepiece optical system and the aperture of the objective optical system. By satisfying condition (18), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0079] Note that by setting the lower limit of conditional expression (18) to 0.57, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (18) to 0.59, 0.62, 0.65, 0.67, 0.70, 0.72, 0.75, 0.80, 0.82, or even 0.85. On the other hand, by setting the upper limit of conditional expression (18) to 1.40, the effects of the first to fourth embodiments can be more reliably achieved. Furthermore, in order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (18) to 1.30, 1.20, 1.15, 1.05, or even 0.95.

[0080] In the observation optical systems according to the first to fourth embodiments, it is desirable that the relay optical system has a cemented lens and that the following conditional expression is satisfied. 1≦Nrc≦7 (19) however, Nrc: number of cemented lenses in the relay optical system

[0081] Condition (19) defines the number of cemented lenses in the relay optical system. By satisfying condition (19), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (i.e., axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide actual field of view, and a compact, lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact, lightweight lens.

[0082] The effects of the first to fourth embodiments can be more reliably achieved by setting the lower limit of conditional expression (19) to 2. In order to further ensure the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (19) to 3, 4, or even 5. On the other hand, the effects of the first to fourth embodiments can be more reliably achieved by setting the upper limit of conditional expression (19) to 6. In order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (19) to 5, 4, 3, or even 2.

[0083] Moreover, it is desirable that the observation optical systems according to the first to fourth embodiments satisfy the following conditional expressions. 4≦Ne≦8 (20) however, Ne: Number of lenses in the eyepiece optical system

[0084] Condition (20) defines the number of lenses in the eyepiece optical system. By satisfying condition (20), various aberrations, such as spherical aberration, coma, astigmatism, curvature of field, chromatic aberration (axial chromatic aberration), and chromatic aberration of magnification, can be effectively corrected, a high magnification can be achieved while maintaining a wide field of view, and a compact and lightweight lens can be achieved. In particular, spherical aberration and coma can be effectively corrected at high magnification while maintaining a compact and lightweight lens.

[0085] The effects of the first to fourth embodiments can be more reliably achieved by setting the lower limit of conditional expression (20) to 5. In order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the lower limit of conditional expression (20) to 6. On the other hand, the effects of the first to fourth embodiments can be more reliably achieved by setting the upper limit of conditional expression (20) to 7. In order to more reliably achieve the effects of the first to fourth embodiments, it is more preferable to set the upper limit of conditional expression (20) to 6, 5, or even 4.

[0086] Here, a description will be given of an example of an observation optical system according to the second embodiment. Fig. 21 is a cross-sectional view showing an observation optical system having a first observation optical system OS1 and a second observation optical system OS2. The first observation optical system OS1 and the second observation optical system OS2 are configured with the same lens components and are arranged in parallel, as an example of the same lens components, respectively, shown as the observation optical systems of the first embodiment.

[0087] The optical apparatus according to this embodiment has an observation optical system with the above-described configuration, which makes it possible to realize an optical apparatus equipped with a large-diameter observation optical system that can effectively correct various aberrations, achieve high magnification while maintaining a wide actual field of view, and also achieve compactness and light weight.

[0088] An example of an optical device equipped with the observation optical system OS of this embodiment will now be described. Fig. 22 is a cross-sectional view showing an example of the configuration of binoculars equipped with the observation optical system OS. The binoculars include a first observation optical system OS1 and a second observation optical system OS2 that is composed of the same lens components as the first observation optical system OS1, and the first observation optical system OS1 and the second observation optical system OS2 are arranged in parallel to form binoculars. The optical device is not limited to the binoculars, but may be a telescope configured with a single observation optical system OS.

[0089] Furthermore, the manufacturing method of the observation optical system OS of the first embodiment relating to the sixth embodiment has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, a first intermediate image I1 being formed between the objective optical system O and the relay optical system R, and a second intermediate image I2 being formed between the relay optical system R and the eyepiece optical system E, and is configured so as to satisfy the following conditional expressions: 0.060 <fe / TL<0.130 (1) however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

[0090] Furthermore, the manufacturing method of the observation optical system OS of the second embodiment relating to the seventh embodiment has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, a first observation optical system OS1 that forms a first intermediate image I1 between the objective optical system O and the relay optical system R, and a second intermediate image I2 between the relay optical system R and the eyepiece optical system E, and further has a second observation optical system OS2 that is composed of the same lens components as the first observation optical system OS1, and the first observation optical system OS1 and the second observation optical system OS2 are arranged in parallel.

[0091] Furthermore, the manufacturing method of the third embodiment of the observation optical system OS relating to the eighth embodiment has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, a first intermediate image I1 being formed between the objective optical system O and the relay optical system R, and a second intermediate image I2 being formed between the relay optical system R and the eyepiece optical system E, and is configured to satisfy the following conditional expressions: 0.040 <Dm / TL<0.350 (2) however, Dm: the maximum air gap between lens surfaces in the observation optical system TL: total optical length of the observation optical system

[0092] Furthermore, a manufacturing method for an observation optical system OS of the fourth embodiment according to the ninth embodiment has, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, a first intermediate image I1 being formed between the objective optical system O and the relay optical system R, and a second intermediate image I2 being formed between the relay optical system R and the eyepiece optical system E, and at least one lens S of the lenses arranged in the objective optical system being configured to satisfy the following conditional expression: 80.00<νds (3) however, νds: Abbe number of the lens S for the d line

[0093] Below, an outline of a manufacturing method for an observation optical system OS according to the sixth and eighth embodiments will be described with reference to Fig. 23. First, the optical system is arranged (S1) to have, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, such that a first intermediate image I1 is formed between the objective optical system O and the relay optical system R, and a second intermediate image I2 is formed between the relay optical system R and the eyepiece optical system E. Next, each optical system is arranged (S2) to satisfy a predetermined conditional expression.

[0094] An outline of a manufacturing method for an observation optical system OS according to the seventh embodiment will now be described with reference to Fig. 24. First, a first observation optical system OS1 is arranged (S1) to have, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, and to form a first intermediate image I1 between the objective optical system O and the relay optical system R, and to form a second intermediate image I2 between the relay optical system R and the eyepiece optical system E. Further, a second observation optical system OS2 is arranged in parallel with the first observation optical system OS1 and is composed of the same lens components as the first observation optical system OS1 (S2).

[0095] An outline of a manufacturing method for an observation optical system OS according to the ninth embodiment will now be described with reference to Fig. 25. First, an optical system is arranged (S1) to have, in order from the object side, an objective optical system O, an erecting optical system, and an eyepiece optical system E, the erecting optical system being a relay optical system R, such that a first intermediate image I1 is formed between the objective optical system O and the relay optical system R, and a second intermediate image I2 is formed between the relay optical system R and the eyepiece optical system E. Next, at least one lens S of the lenses arranged in the objective optical system is configured to satisfy a predetermined conditional expression (S2).

[0096] According to the above-mentioned manufacturing method of an observation optical system, it is possible to manufacture a large-diameter observation optical system in which various aberrations are well corrected, high magnification is achieved while maintaining a wide actual field of view, and it is also possible to reduce the size and weight.

[0097] It should be noted that the conditions and configurations described above each exert the effects described above, and are not limited to those that satisfy all of the conditions and configurations; the effects described above can be obtained by satisfying any one of the conditions or configurations, or a combination of any one of the conditions or configurations.

[0098] Furthermore, the examples described below are specific examples of the present invention, and the present invention is not limited to these. The following content can be adopted as appropriate within the scope that does not impair the optical performance of the observation optical system of this embodiment.

[0099] For example, the following embodiments are presented as numerical examples of the observation optical system. Some lenses or a partial lens group may be used as focusing lenses, and the invention can also be applied to autofocusing, and motor driving for autofocusing (such as an ultrasonic motor, a stepping motor, or a VCM motor) is also possible.

[0100] In addition, some lenses or partial lens groups may be moved so as to have a displacement component perpendicular to the optical axis, or may be rotated (oscillated) in a plane including the optical axis to create an anti-vibration lens that corrects image blur caused by camera shake or the like.

[0101] The lens surface may be spherical, flat, or aspherical. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment and prevents degradation of optical performance due to errors in processing and assembly adjustment. It is also preferable because degradation of imaging performance is minimal even when the image plane is misaligned. If the lens surface is aspherical, the aspherical surface may be any of the following aspherical surfaces: a ground aspherical surface, a glass-molded aspherical surface in which glass is molded into an aspherical shape, or a hybrid aspherical surface in which a resin is molded into an aspherical shape on the surface of glass. The lens surface may also be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

[0102] The aperture stop is preferably disposed inside or outside the lens group, but it is also possible to use the lens frame to fulfill the role of the aperture stop without providing a member serving as the aperture stop.

[0103] Furthermore, each lens surface may be coated with an anti-reflection coating that has high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high contrast and high optical performance.

[0104] With the above-described configuration, it is possible to provide a large-aperture observation optical system OS that has good optical performance, achieves high magnification while maintaining a wide actual field of view, and is also small and lightweight, and an optical device that includes this observation optical system OS.

[0105] Each example according to this embodiment will be described below with reference to the drawings. Tables 1 to 10 are tables of specifications for the first to tenth examples.

[0106] Figure 1 is a cross-sectional view of the observation optical system of the first embodiment, with the left side of the observation optical system OS indicating the object side and the right side indicating the observation side, and showing, from the object side, the objective lens O, the first intermediate image I1, the relay lens R, the second intermediate image I2, the eyepiece lens E, and the eyepoint EP. The lenses in FIG. 1 are designated L11, L12, L13, etc., in order from the object side (left side of the page).

[0107] 1 relating to the first embodiment are used independently for each embodiment to avoid complication of explanation due to an increase in the number of digits of the reference symbols. Therefore, even if common reference symbols are used with drawings relating to other embodiments, they do not necessarily have the same configuration as the other embodiments.

[0108] 2 is a diagram showing various aberrations of the observation optical system according to Example 1, illustrating spherical aberration, astigmatism, lateral aberration, distortion, chromatic aberration of magnification, etc. Each aberration diagram shows that the observation optical system OS has excellent imaging performance with various aberrations well corrected. where h is the height from the optical axis and is 1 / 2 the objective lens diameter Φ, θ is 1 / 2 the actual field of view, and d and g are the aberration curves for the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm), respectively. Also, for astigmatism, the solid line indicates the sagittal image plane and the dotted line indicates the meridional image plane, and the horizontal axis is in units of 1 / m. In each embodiment, the C-line (wavelength 656.3 nm), d-line (wavelength 587.6 nm), F-line (wavelength 486.1 nm), and g-line (wavelength 435.8 nm) are selected as the targets for calculating the aberration characteristics.

[0109] In the table (Basic specifications), Φ is the diameter of the objective lens, Φe is the maximum effective diameter of the eyepiece, 2θ is the actual field of view (maximum angle of incidence, unit: °), 2θ' is the apparent field of view (maximum angle of emergence, unit: °), ER is the eye relief, TL is the total optical length of the observation optical system (the distance from the frontmost lens surface to the last lens surface on the optical axis), fo is the focal length of the objective lens, fr is the focal length of the relay lens, fe is the focal length of the eyepiece lens, fcom is the combined focal length of the objective lens and relay lens, Dm is the maximum air space between lens surfaces in the observation optical system, nds is the refractive index of the objective lens for the d line of lens S, where νds is the Abbe number for the d-line of lens S in the objective lens, D1 is the distance from the object side of the lens component second from the object side in the objective lens to the observation side of the eyepiece, D2 is the distance from the observation side of the relay lens to the object side of the eyepiece, fe1 is the focal length of the negative lens in the eyepiece closest to the object, rL is the radius of curvature of the lens surface in the eyepiece closest to the observation side, Nrc is the number of cemented lenses in the relay lens, and Ne is the number of lenses in the eyepiece.

[0110] In the (surface data) table, the surface number indicates the order of the optical surface from the object side along the direction of light ray travel, r is the radius of curvature of each optical surface, d is the surface spacing, which is the distance on the optical axis from each optical surface to the next optical surface (or intermediate image plane, eye point), nd is the refractive index of the optical element material with respect to the d-line, and νd is the Abbe number of the optical element material with respect to the d-line. Also, "∞" for the radius of curvature indicates a flat surface or an intermediate image plane. The refractive index of air, "1.00000," is omitted.

[0111] In the table (aspheric surface data), the aspheric surface is expressed by the following formula (a), where y is the height in the direction perpendicular to the optical axis, S(y) is the distance (amount of sag) along the optical axis from the tangent plane of the vertex of each aspheric surface at the height y to each aspheric surface, r is the radius of curvature (paraxial radius of curvature) of the reference spherical surface, k is the conic constant, and An is the aspheric coefficient of order n (n=4, 6, 8, 10). Note that in the following examples, "En" is "×10 -n ". For example, "-6.391E-05" indicates "-6.391×10 -5 " indicates.

[0112] S(y)=(y 2 / r) / [1+{1-(k+1)×y 2 / r 2} 1 / 2 ] +A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 (a)

[0113] In each example, the second-order aspherical coefficient A2 is omitted because it is 0. In the table of each example, aspherical surfaces are marked with an * to the right of the surface number.

[0114] In the following, all specifications such as focal length f, radius of curvature r, surface spacing d, and other lengths are generally expressed in "mm" unless otherwise specified, but this is not limited to this because the same optical performance can be obtained even when the optical system is proportionally enlarged or reduced. Furthermore, the unit is not limited to "mm" and other appropriate units can be used.

[0115] The explanations of the tables and aberration diagrams up to this point are common to all the embodiments, and will not be repeated below.

[0116] (First Example) FIG. 1 is a cross-sectional view of the observation optical system according to the first embodiment. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER. The above explanation is common to all the embodiments, and will not be repeated below.

[0117] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22 together, a meniscus positive lens L23 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L24 and a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a meniscus positive lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L28 and a biconcave negative lens L29, and a cemented lens formed by cementing a biconcave negative lens L30 and a meniscus positive lens L31 with its convex surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L41 with its concave surface facing the object side and a positive meniscus lens L42 with its concave surface facing the object side, a cemented lens formed by cementing together a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0118] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0119] Table 1 below shows the values ​​of each parameter in the first embodiment. (Table 1) First Example (Basic specifications) Magnification 8.01 Φ (objective lens diameter) 42.00 Φe (maximum effective diameter of eyepiece) 36.40 2θ (actual field of view) 9.64 2θ' (apparent field of view) 68.0 ER (Eye Relief) 15.594 TL (total optical length of observation optical system) 189.299 fo (focal length of objective lens) 74.123 fr (focal length of relay lens) 9.920 fe (focal length of eyepiece) 14.821 fcom (combined focal length of objective lens and relay lens) -118.738 Dm (maximum air gap between lens surfaces in the observation optical system) 17.869 nds (refractive index of the objective lens S for the d line) 1.45600 νds (Abbe number for the d line of the objective lens S) 91.37 D1 (distance from the object side of the second-most lens element of the objective lens to the most observable side of the eyepiece) 175.599 D2 (distance from the most observable side of the relay lens to the most observable side of the eyepiece) 7.500 fe1 (focal length of the negative eyepiece lens closest to the object) -67.986 rL (radius of curvature of the lens surface closest to the observation side of the eyepiece) 97.317 Nrc (number of cemented lenses in relay lens) 5 Ne (number of lenses in eyepiece) 6 (surface data) Surface number rd nd νd 1 43.121 2.000 1.80400 46.60 2 35.000 11.500 1.45600 91.37 3 -88.987 0.200 4 37.680 11.200 1.45600 91.37 5 -44.875 1.500 1.80400 46.60 6 115.412 17.869 7 -122.716 3.250 1.60300 65.44 8 -60.947 5.000 1.84666 23.80 9 -40.644 7.712 10 35.000 2.000 1.48749 70.32 11 19.382 10.000 12 -10.747 1.000 1.48749 70.32 13 -1402.896 4.010 14 (first intermediate image) ∞ 4.000 15 14.000 6.000 1.85026 32.35 16 -18.838 1.000 1.75520 27.57 17 11.203 3.000 18 -184.484 3.896 1.80400 46.60 19 -14.717 0.200 20 19.067 5.528 1.59319 67.90 21 -10.123 1.000 1.84666 23.80 22 -65.037 11.514 23 53.786 3.121 1.72916 54.61 24 -23.297 2.273 1.84666 23.80 25 -22.813 5.161 26 12.399 5.792 1.79504 28.69 27 -11.301 3.604 1.84666 23.80 28 10.195 3.500 29 -11.000 2.200 1.54814 45.51 30 15.746 3.546 1.80400 46.60 31 79.726 3.495 32 (second intermediate image) ∞ 4.005 33 -55.570 1.200 1.84666 23.80 34 -1622.286 13.800 1.80400 46.60 35 -21.623 0.200 36 237.047 6.200 1.72916 54.61 37 -138.449 0.200 38 41.449 6.300 1.59319 67.90 39 -357.089 0.200 40 23.500 9.923 1.59319 67.90 41 -56.603 1.200 1.80518 25.45 42 97.317 15.594 43 (eye point)

[0120] FIG. 2 is a diagram showing various aberrations of the observation optical system according to Example 1, and it can be seen that the various aberrations are well corrected and that the imaging performance is excellent.

[0121] (Second Example) FIG. 3 is a cross-sectional view of the observation optical system according to the second embodiment. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0122] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22 together, a meniscus positive lens L23 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L24 and a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a meniscus positive lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a meniscus positive lens L28 with its convex surface facing the object side and a meniscus negative lens L29 with its convex surface facing the object side, and a cemented lens formed by cementing a meniscus negative lens L30 with its concave surface facing the object side and a meniscus negative lens L31 with its concave surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing a biconcave negative lens L41 and a biconvex positive lens L42, a cemented lens formed by cementing a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0123] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0124] Table 2 below shows the values ​​of each parameter in the second embodiment. (Table 2) Second Example (Basic specifications) Magnification 10.02 Φ 42.00 Φe 42.00 2θ 8.01 2θ' 70.0 ER 15.051 TL 199.909 fo 74.123 fr 8.708 fe 17.008 fcom -170.454 Dm 17.869 nds 1.45600 νds 91.37 D1 186.209 D2 14.264 fe1 -82.205 rL 80.000 NRC 5 Ne 6 (surface data) Surface number rd nd νd 1 43.121 2.000 1.80400 46.60 2 35.000 11.500 1.45600 91.37 3 -88.987 0.200 4 37.680 11.200 1.45600 91.37 5 -44.875 1.500 1.80400 46.60 6 115.412 17.869 7 -122.716 3.250 1.60300 65.44 8 -60.947 5.000 1.84666 23.80 9 -40.644 7.712 10 35.000 2.000 1.48749 70.32 11 19.382 10.000 12 -10.747 1.000 1.48749 70.32 13 -1402.896 4.010 14 (first intermediate image) ∞ 4.000 15 14.000 6.000 1.85026 32.35 16 -18.838 1.000 1.75520 27.57 17 11.203 3.000 18 -184.484 3.896 1.80400 46.60 19 -14.717 0.200 20 19.067 5.528 1.59319 67.90 21 -10.123 1.000 1.84666 23.80 22 -65.037 11.514 23 53.786 3.121 1.72916 54.61 24 -23.297 2.273 1.84666 23.80 25 -22.813 10.481 26 10.165 2.913 1.83481 42.73 27 12.059 2.200 1.84666 23.80 28 10.000 3.200 29 -10.000 1.878 1.85026 32.35 30 -34.290 2.200 1.78472 25.64 31 -372.546 9.203 32 (second intermediate image) ∞ 5.061 33 -76.790 1.500 1.84666 23.80 34 750.000 14.300 1.75500 52.34 35 -25.194 0.200 36 74.833 6.900 1.48749 70.32 37 -133.618 0.200 38 51.837 7.600 1.48749 70.32 39 -141.285 0.200 40 24.300 11.900 1.59319 67.90 41 -72.611 1.200 1.80518 25.45 42 80.000 15.051 43 (eye point)

[0125] FIG. 4 is a diagram showing various aberrations of the observation optical system according to the second example, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0126] (Third Example) FIG. 5 is a cross-sectional view of the observation optical system according to the third example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0127] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22 together, a meniscus positive lens L23 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L24 and a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a meniscus positive lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L28 and a biconcave negative lens L29, and a cemented lens formed by cementing a biconcave negative lens L30 and a meniscus positive lens L31 with its convex surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L41 with its concave surface facing the object side and a positive meniscus lens L42 with its concave surface facing the object side, a cemented lens formed by cementing together a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0128] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0129] Table 3 below shows the values ​​of each parameter in the third embodiment. (Table 3) Third Example (Basic specifications) Magnification 8.00 Φ 42.00 Φe 36.40 2θ 9.64 2θ' 68.0 ER 15.645 TL 190.101 fo 74.221 fr 9.920 fe 14.821 fcom -118.553 Dm 18.715 nds 1.43384 νds 95.16 D1 176.401 D2 7.456 fe1 -67.986 rL 97.317 NRC 5 Ne 6 (surface data) Surface number rd nd νd 1 44.718 2.000 1.80400 46.60 2 39.747 11.500 1.43384 95.16 3 -75.315 0.200 4 37.920 11.200 1.43384 95.16 5 -40.425 1.500 1.80400 46.60 6 127.086 18.715 7 -157.654 3.250 1.60300 65.44 8 -54.000 5.000 1.84666 23.80 9 -39.235 7.712 10 35.000 2.000 1.48749 70.32 11 19.382 10.000 12 -10.747 1.000 1.48749 70.32 13 -1402.896 4.010 14 (first intermediate image) ∞ 4.000 15 14.000 6.000 1.85026 32.35 16 -18.838 1.000 1.75520 27.57 17 11.203 3.000 18 -184.484 3.896 1.80400 46.60 19 -14.717 0.200 20 19.067 5.528 1.59319 67.90 21 -10.123 1.000 1.84666 23.80 22 -65.037 11.514 23 53.786 3.121 1.72916 54.61 24 -23.297 2.273 1.84666 23.80 25 -22.813 5.161 26 12.399 5.792 1.79504 28.69 27 -11.301 3.604 1.84666 23.80 28 10.195 3.500 29 -11.000 2.200 1.54814 45.51 30 15.746 3.546 1.80400 46.60 31 79.726 3.449 32 (second intermediate image) ∞ 4.007 33 -55.570 1.200 1.84666 23.80 34 -1622.286 13.800 1.80400 46.60 35 -21.623 0.200 36 237.047 6.200 1.72916 54.61 37 -138.449 0.200 38 41.449 6.300 1.59319 67.90 39 -357.089 0.200 40 23.500 9.923 1.59319 67.90 41 -56.603 1.200 1.80518 25.45 42 97.317 15.645 43 (eye point)

[0130] FIG. 6 is a diagram showing various aberrations of the observation optical system according to Example 3, and it can be seen that the various aberrations are well corrected and that the imaging performance is excellent.

[0131] (Fourth Example) FIG. 7 is a cross-sectional view of the observation optical system according to the fourth example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0132] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22 together, a meniscus positive lens L23 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L24 and a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a meniscus positive lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a meniscus positive lens L28 with its convex surface facing the object side and a meniscus negative lens L29 with its convex surface facing the object side, and a cemented lens formed by cementing a meniscus negative lens L30 with its concave surface facing the object side and a meniscus negative lens L31 with its concave surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing a biconcave negative lens L41 and a biconvex positive lens L42, a cemented lens formed by cementing a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0133] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0134] Table 4 below shows the values ​​of each parameter in the fourth embodiment. (Table 4) Fourth Example (Basic specifications) Magnification 9.99 Φ 42.00 Φe 42.00 2θ 8.01 2θ' 70.0 ER 15.130 TL 200.664 fo 74.221 fr 8.708 fe 17.008 fcom -169.878 Dm 18.715 nds 1.43384 νds 95.16 D1 186.964 D2 14.173 fe1 -82.205 rL 80.000 NRC 5 Ne 6 (surface data) Surface number rd nd νd 1 44.718 2.000 1.80400 46.60 2 39.747 11.500 1.43384 95.16 3 -75.315 0.200 4 37.920 11.200 1.43384 95.16 5 -40.425 1.500 1.80400 46.60 6 127.086 18.715 7 -157.654 3.250 1.60300 65.44 8 -54.000 5.000 1.84666 23.80 9 -39.235 7.712 10 35.000 2.000 1.48749 70.32 11 19.382 10.000 12 -10.747 1.000 1.48749 70.32 13 -1402.896 4.010 14 (first intermediate image) ∞ 4.000 15 14.000 6.000 1.85026 32.35 16 -18.838 1.000 1.75520 27.57 17 11.203 3.000 18 -184.484 3.896 1.80400 46.60 19 -14.717 0.200 20 19.067 5.528 1.59319 67.90 21 -10.123 1.000 1.84666 23.80 22 -65.037 11.514 23 53.786 3.121 1.72916 54.61 24 -23.297 2.273 1.84666 23.80 25 -22.813 10.481 26 10.165 2.913 1.83481 42.73 27 12.059 2.200 1.84666 23.80 28 10.000 3.200 29 -10.000 1.878 1.85026 32.35 30 -34.290 2.200 1.78472 25.64 31 -372.546 9.109 32 (second intermediate image) ∞ 5.064 33 -76.790 1.500 1.84666 23.80 34 750.000 14.300 1.75500 52.34 35 -25.194 0.200 36 74.833 6.900 1.48749 70.32 37 -133.618 0.200 38 51.837 7.600 1.48749 70.32 39 -141.285 0.200 40 24.300 11.900 1.59319 67.90 41 -72.611 1.200 1.80518 25.45 42 80.000 15.130 43 (eye point)

[0135] FIG. 8 is a diagram showing various aberrations of the observation optical system according to Example 4, and it is clear that the various aberrations are well corrected and that the imaging performance is excellent.

[0136] (Fifth Example) FIG. 9 is a cross-sectional view of the observation optical system according to the fifth example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0137] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22 together, a meniscus positive lens L23 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L24 and a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a meniscus positive lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L28 and a biconcave negative lens L29, and a cemented lens formed by cementing a biconcave negative lens L30 and a meniscus positive lens L31 with its convex surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L41 with its concave surface facing the object side and a positive meniscus lens L42 with its concave surface facing the object side, a cemented lens formed by cementing together a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0138] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0139] Table 5 below shows the values ​​of each parameter in the fifth embodiment. (Table 5) Fifth Example (Basic specifications) Magnification 8.01 Φ 42.00 Φe 36.20 2θ 9.64 2θ' 68.0 ER 15.598 TL 189.348 fo 74.119 fr 9.920 fe 14.821 fcom -118.702 Dm 17.919 nds 1.49782 νds 82.57 D1 175.648 D2 7.499 fe1 -67.986 rL 97.317 NRC 5 Ne 6 (surface data) Surface number rd nd νd 1 47.758 2.000 1.80400 46.60 2 37.703 11.500 1.49782 82.57 3 -82.986 0.200 4 36.846 11.200 1.49782 82.57 5 -41.138 1.500 1.80400 46.60 6 73.398 17.919 7 -116.592 3.250 1.60300 65.44 8 -47.881 5.000 1.84666 23.80 9 -36.763 7.712 10 35.000 2.000 1.48749 70.32 11 19.382 10.000 12 -10.747 1.000 1.48749 70.32 13 -1402.896 4.010 14 (first intermediate image) ∞ 4.000 15 14.000 6.000 1.85026 32.35 16 -18.838 1.000 1.75520 27.57 17 11.203 3.000 18 -184.484 3.896 1.80400 46.60 19 -14.717 0.200 20 19.067 5.528 1.59319 67.90 21 -10.123 1.000 1.84666 23.80 22 -65.037 11.514 23 53.786 3.121 1.72916 54.61 24 -23.297 2.273 1.84666 23.80 25 -22.813 5.161 26 12.399 5.792 1.79504 28.69 27 -11.301 3.604 1.84666 23.80 28 10.195 3.500 29 -11.000 2.200 1.54814 45.51 30 15.746 3.546 1.80400 46.60 31 79.726 3.491 32 (second intermediate image) ∞ 4.008 33 -55.570 1.200 1.84666 23.80 34 -1622.286 13.800 1.80400 46.60 35 -21.623 0.200 36 237.047 6.200 1.72916 54.61 37 -138.449 0.200 38 41.449 6.300 1.59319 67.90 39 -357.089 0.200 40 23.500 9.923 1.59319 67.90 41 -56.603 1.200 1.80518 25.45 42 97.317 15.598 43 (eye point)

[0140] FIG. 10 is a diagram showing various aberrations of the observation optical system according to Example 5, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0141] (Sixth Example) FIG. 11 is a cross-sectional view of the observation optical system according to the sixth example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0142] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22 together, a meniscus positive lens L23 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L24 and a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a meniscus positive lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a meniscus positive lens L28 with its convex surface facing the object side and a meniscus negative lens L29 with its convex surface facing the object side, and a cemented lens formed by cementing a meniscus negative lens L30 with its concave surface facing the object side and a meniscus negative lens L31 with its concave surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing a biconcave negative lens L41 and a biconvex positive lens L42, a cemented lens formed by cementing a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0143] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0144] Table 6 below shows the values ​​of each parameter in the sixth embodiment. (Table 6) Sixth Example (Basic specifications) Magnification 10.02 Φ 42.00 Φe 42.00 2θ 8.00 2θ' 70.0 ER 15.036 TL 199.958 fo 74.119 fr 8.708 fe 17.008 fcom -170.375 Dm 17.919 nds 1.49782 νds 82.57 D1 186.258 D2 14.263 fe1 -82.205 rL 80.000 NRC 5 Ne 6 (surface data) Surface number rd nd νd 1 47.758 2.000 1.80400 46.60 2 37.703 11.500 1.49782 82.57 3 -82.986 0.200 4 36.846 11.200 1.49782 82.57 5 -41.138 1.500 1.80400 46.60 6 73.398 17.919 7 -116.592 3.250 1.60300 65.44 8 -47.881 5.000 1.84666 23.80 9 -36.763 7.712 10 35.000 2.000 1.48749 70.32 11 19.382 10.000 12 -10.747 1.000 1.48749 70.32 13 -1402.896 4.010 14 (first intermediate image) ∞ 4.000 15 14.000 6.000 1.85026 32.35 16 -18.838 1.000 1.75520 27.57 17 11.203 3.000 18 -184.484 3.896 1.80400 46.60 19 -14.717 0.200 20 19.067 5.528 1.59319 67.90 21 -10.123 1.000 1.84666 23.80 22 -65.037 11.514 23 53.786 3.121 1.72916 54.61 24 -23.297 2.273 1.84666 23.80 25 -22.813 10.481 26 10.165 2.913 1.83481 42.73 27 12.059 2.200 1.84666 23.80 28 10.000 3.200 29 -10.000 1.878 1.85026 32.35 30 -34.290 2.200 1.78472 25.64 31 -372.546 9.195 32 (second intermediate image) ∞ 5.068 33 -76.790 1.500 1.84666 23.80 34 750.000 14.300 1.75500 52.34 35 -25.194 0.200 36 74.833 6.900 1.48749 70.32 37 -133.618 0.200 38 51.837 7.600 1.48749 70.32 39 -141.285 0.200 40 24.300 11.900 1.59319 67.90 41 -72.611 1.200 1.80518 25.45 42 80.000 15.036 43 (eye point)

[0145] FIG. 12 is a diagram showing various aberrations in the observation optical system according to Example 6, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0146] (Seventh Example) FIG. 13 is a cross-sectional view of the observation optical system according to the seventh example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0147] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a positive meniscus lens L13 with its convex surface facing the object side, and a positive meniscus lens L14 with its convex surface facing the object side. The relay lens R is composed of, in order from the object side, a biconcave negative lens L21, a biconvex positive lens L22, a meniscus lens-shaped positive lens L23 with its concave surface facing the object side, a meniscus lens-shaped positive lens L24 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L25 and a biconcave negative lens L26, a cemented lens formed by cementing a biconcave negative lens L27 and a biconvex positive lens L28, a meniscus lens-shaped negative lens L29 with its concave surface facing the object side, a biconvex positive lens L30, a meniscus lens-shaped positive lens L31 with its convex surface facing the object side, a biconcave negative lens L32, and a meniscus lens-shaped positive lens L33 with its concave surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing a biconcave negative lens L41 and a biconvex positive lens L42, a biconvex positive lens L43, a meniscus lens-shaped negative lens L44 with its concave surface facing the object side, and a meniscus lens-shaped positive lens L45 with its convex surface facing the object side.

[0148] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d7, which satisfies conditional formula (2); lenses S of the objective lens O, which satisfy conditional formulas (3) and (4), are L12 and L13; the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d32 and d33, which satisfies conditional formula (15); and the lens of the eyepiece optical system, which is nearest to the object and has a focal length fe1, is L41, which satisfies conditional formula (16).

[0149] Table 7 below shows the values ​​of each parameter in the seventh embodiment. (Table 7) Seventh Example (Basic specifications) Magnification 10.02 Φ 42.00 Φe 33.00 2θ 8.00 2θ' 69.9 ER 13.932 TL 200.000 fo 67.687 fr 8.899 fe 16.306 fcom -163.307 Dm 50.800 nds 1.43384 νds 95.163 D1 189.600 D2 9.600 fe1 -30.947 rL 116.740 NRC 2 Ne 5 (surface data) Surface number rd nd νd 1 84.551 2.000 1.90265 35.771 2 40.733 8.200 1.43384 95.163 3 -248.700 0.200 4 39.210 7.300 1.43384 95.163 5 1658.312 15.800 6 33.563 3.300 1.49782 82.571 7 42.991 47.800 8 (first intermediate image) ∞ 3.000 9 -9.091 1.400 1.48749 70.441 10 59.187 1.300 11* 233.980 5.200 1.85207 40.149 12 -15.000 0.500 13 -70.835 4.600 1.87071 40.729 14 -16.233 1.000 15* -54.038 3.000 1.85207 40.149 16 -41.207 1.600 17 12.973 5.300 1.71700 47.928 18 -9.981 1.000 1.86074 23.078 19 9.939 1.600 20 -19.572 1.800 1.75211 25.048 21 9.091 3.900 1.70000 48.081 22 -13.993 5.000 23 -9.091 2.700 1.86074 23.078 24 -9.725 1.900 25 30.752 3.000 1.86074 23.078 26 -37.124 7.100 27 55.790 2.900 1.48749 70.441 28 100.180 6.400 29 -9.091 3.000 1.86074 23.078 30 67.630 2.300 31 -20.738 3.500 1.85207 40.149 32* -17.000 4.477 33 (second intermediate image) ∞ 5.123 34 -237.620 3.000 1.92286 20.880 35 32.658 12.000 1.80400 46.598 36 -25.910 0.200 37 37.153 9.500 1.59319 67.901 38 -44.709 1.500 1.86074 23.078 39 -108.822 0.200 40 21.968 6.400 1.59319 67.901 41 116.740 13.932 42 (eye point) (aspheric data) Surface k A4 A6 A8 A10 11 0.000E+00 3.291E-05 1.425E-07 -1.251E-08 5.676E-11 15 0.000E+00 -6.391E-05 1.771E-08 -4.416E-09 7.216E-11 32 0.000E+00 -1.440E-04 -1.126E-06 2.418E-08 -2.505E-10

[0150] FIG. 14 is a diagram showing various aberrations of the observation optical system according to Example 7, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0151] (Eighth Example) FIG. 15 is a cross-sectional view of the observation optical system according to the eighth example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0152] The objective lens O is composed of, in order from the object side, a cemented lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, a cemented lens formed by cementing together a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens formed by cementing together a meniscus-shaped positive lens L15 with its concave surface facing the object side and a meniscus-shaped positive lens L16 with its concave surface facing the object side, a meniscus-shaped negative lens L17 with its convex surface facing the object side, and a meniscus-shaped negative lens L18 with its concave surface facing the object side. The relay lens R is composed of, in order from the object side, a cemented lens formed by cementing a biconvex positive lens L21 and a biconcave negative lens L22, a meniscus-shaped positive lens L23 with its concave surface facing the object side, The lens is made up of a cemented lens formed by cementing a biconvex positive lens L24 to a meniscus negative lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 to a meniscus negative lens L27 with its concave surface facing the object side, a cemented lens formed by cementing a meniscus positive lens L28 with its convex surface facing the object side to a meniscus negative lens L29 with its convex surface facing the object side, and a cemented lens formed by cementing a meniscus negative lens L30 with its concave surface facing the object side to a meniscus negative lens L31 with its concave surface facing the object side. The eyepiece E is composed of, in order from the object side, a cemented lens formed by cementing together a negative meniscus lens L41 with its concave surface facing the object side and a positive meniscus lens L42 with its concave surface facing the object side, a cemented lens formed by cementing together a biconvex positive lens L43, a biconvex positive lens L44, a biconvex positive lens L45, and a biconcave negative lens L46.

[0153] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d6, which satisfies conditional formula (2); lenses S of the objective lens O are L12 and L13, which satisfy conditional formulas (3) and (4); the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d31 and d32, which satisfies conditional formula (15); and the lens of the eyepiece optical system that is nearest to the object and has a focal length fe1 is L41, which satisfies conditional formula (16).

[0154] Table 8 below shows the values ​​of each parameter in the eighth embodiment. (Table 8) Eighth Example (Basic specifications) Magnification 10.07 Φ 42.00 Φe 46.60 2θ 9.00 2θ' 76.8 ER 15.101 TL 200.062 fo 71.312 fr 9.803 fe 18.557 fcom -186.860 Dm 16.228 nds 1.45600 νds 91.3748 D1 186.362 D2 15.299 fe1 -103.315 rL 80.000 NRC 5 Ne 6 (surface data) Surface number rd nd νd 1 40.857 2.000 1.80400 46.5977 2 35.000 11.500 1.45600 91.3748 3 -102.820 0.200 4 35.386 11.200 1.45600 91.3748 5 -45.471 1.500 1.80400 46.5977 6 140.895 16.228 7 -69.136 2.675 1.60300 65.4413 8 -47.171 3.216 1.84666 23.7966 9 -36.089 5.490 10 35.000 2.000 1.48749 70.3188 11 19.991 10.000 12 -9.777 1.000 1.48749 70.3188 13 -181.036 4.311 14 (first intermediate image) ∞ 4.000 15 14.492 6.000 1.85026 32.3529 16 -20.373 1.000 1.75520 27.5711 17 11.838 3.000 18 -703.488 3.900 1.80400 46.5977 19 -15.212 0.200 20 18.621 6.200 1.59319 67.9006 21 -10.052 1.000 1.84666 23.7966 22 -105.579 9.762 23 49.290 3.572 1.72916 54.6115 24 -17.841 2.200 1.84666 23.7966 25 -21.598 7.345 26 10.300 2.599 1.83481 42.7334 27 12.739 2.200 1.84666 23.7966 28 11.000 3.600 29 -10.000 5.965 1.85026 32.3529 30 -39.023 5.800 1.78472 25.6384 31 -146.626 10.044 32 (second intermediate image) ∞ 5.255 33 -82.935 1.500 1.84666 23.7966 34 -1612.106 14.700 1.75500 52.3363 35 -28.000 0.200 36 1016.755 8.300 1.48749 70.3188 37 -52.878 0.200 38 55.061 6.900 1.48749 70.3188 39 -3925.676 0.200 40 23.526 11.900 1.59319 67.9006 41 -191.952 1.200 1.80518 25.4483 42 80.000 15.101 43 (eye point)

[0155] FIG. 16 is a diagram showing various aberrations of the observation optical system according to Example 8, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0156] (Ninth Example) FIG. 17 is a cross-sectional view of the observation optical system according to the ninth example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0157] The objective lens O is composed of, in order from the object side, a biconvex positive lens L11, a meniscus positive lens L12 with its convex surface facing the object side, a biconvex positive lens L13, and a biconcave negative lens L14 cemented together. The relay lens R is composed of, in order from the object side, a biconcave negative lens L21, a biconvex positive lens L22, a meniscus lens-shaped positive lens L23 with its convex surface facing the object side, a biconcave negative lens L24, a meniscus lens-shaped positive lens L25 with its concave surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L26 and a biconcave negative lens L27, a cemented lens formed by cementing a biconvex positive lens L28 and a biconcave negative lens L29, a meniscus lens-shaped positive lens L30 with its concave surface facing the object side, a meniscus lens-shaped positive lens L31 with its convex surface facing the object side, and a biconcave negative lens L32. The eyepiece E is composed of, in order from the object side, a positive lens L41 having a meniscus lens shape with its concave surface facing the object side, a cemented lens formed by cementing together a biconvex positive lens L42 and a negative lens L43 having a meniscus lens shape with its concave surface facing the object side, and a positive lens L44 having a meniscus lens shape with its convex surface facing the object side.

[0158] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d4, which satisfies conditional formula (2); lens S of the objective lens O, which satisfies conditional formulas (3) and (4), is L12; the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system is surface spacing d30 and d31, which satisfies conditional formula (15); and the lens of the eyepiece optical system, which has the focal length fe1 of the negative lens nearest to the object side and satisfies conditional formula (16), is L43.

[0159] Table 9 below shows the values ​​of each parameter in the ninth embodiment. (Table 9) Ninth Example (Basic specifications) Magnification 10.00 Φ 42.00 Φe 27.80 2θ 8.00 2θ' 70.0 ER 15.474 TL 199.458 fo 74.728 fr 14.199 fe 13.829 fcom -138.287 Dm 28.195 nds 1.49782 νds 82.57 D1 193.771 D2 12.630 fe1 -21.838 rL 1962.631 NRC 2 Ne 4 (surface data) Surface number rd nd νd 1 67.351 5.473 1.66382 27.35 2 -1855.800 0.214 3 49.650 5.084 1.49782 82.57 4 182.310 28.195 5 17.696 4.897 1.72916 54.61 6 -21.785 2.925 1.84666 23.80 7 11.429 18.856 8 (first intermediate image) ∞ 3.000 9 -22.325 1.000 1.84666 23.80 10 25.203 2.782 11 1178.570 4.834 1.99900 30.00 12 -13.733 0.238 13 23.399 2.835 1.92110 36.05 14 51.184 18.855 15 -28.307 3.000 1.84666 23.80 16 17.303 0.896 17 -157.551 2.744 1.83917 42.02 18 -17.387 0.200 19 15.717 4.823 1.88000 41.00 20 -10.000 1.000 1.84666 23.80 21 10.000 0.265 22 10.742 4.930 1.86869 41.27 23 -10.000 3.000 1.84666 23.80 24 35.480 21.682 25 -28.050 3.631 1.85000 23.00 26 -16.187 1.051 27 16.634 4.007 1.85000 23.00 28 44.723 7.236 29 -16.869 1.052 1.71524 28.35 30 12.006 8.503 31 (second intermediate image) ∞ 4.127 32 -26.662 7.509 1.75500 52.34 33 -14.916 0.200 34 146.137 12.278 1.75500 52.34 35 -13.606 1.000 1.84666 23.80 36 -53.250 0.200 37 21.068 6.936 1.75500 52.34 38 1962.631 15.474 39 (eye point)

[0160] FIG. 18 is a diagram showing various aberrations in the observation optical system according to Example 9, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0161] (Tenth Example) FIG. 19 is a cross-sectional view of the observation optical system according to the tenth example. The observation optical system OS according to this embodiment is composed of, in order from the object side, an objective lens O, an erecting optical relay lens R, and an eyepiece lens E. A first intermediate image I1 is formed between the objective lens O and the relay lens R, and a second intermediate image I2 is formed between the relay lens R and the eyepiece lens E, and observation is performed through the eyepiece lens E at an eyepoint EP located at the eye relief ER.

[0162] The objective lens O is composed of, in order from the object side, a positive lens L11 having a meniscus lens shape with its convex surface facing the object side, a positive lens L12 having a meniscus lens shape with its convex surface facing the object side, a biconvex positive lens L13, and a biconcave negative lens L14. The relay lens R is composed of, in order from the object side, a biconcave negative lens L21, a meniscus lens-shaped positive lens L22 with its concave surface facing the object side, a meniscus lens-shaped negative lens L23 with its concave surface facing the object side, a meniscus lens-shaped positive lens L24 with its convex surface facing the object side, a biconcave negative lens L25, a cemented lens formed by cementing a biconcave negative lens L26 and a biconvex positive lens L27, a cemented lens formed by cementing a biconvex positive lens L28 and a biconcave negative lens L29, a meniscus lens-shaped positive lens L30 with its concave surface facing the object side, a meniscus lens-shaped positive lens L31 with its convex surface facing the object side, and a biconcave negative lens L32. The eyepiece E is composed of, in order from the object side, a meniscus-shaped positive lens L41 with its concave surface facing the object side, a cemented lens formed by cementing together a biconcave negative lens L42 and a biconvex positive lens L43, and a meniscus-shaped positive lens L44 with its convex surface facing the object side.

[0163] In this observation optical system, the maximum air spacing Dm between lens surfaces in the observation optical system is surface spacing d4, which satisfies conditional formula (2); lenses S of the objective lens O, which satisfy conditional formulas (3) and (4), are L11 and L12; the distance D2 from the surface nearest to the observation side of the relay optical system to the surface nearest to the object side of the eyepiece optical system, which satisfies conditional formula (15), is surface spacing d31 and d32; and the lens of the eyepiece optical system, which has the focal length fe1 of the negative lens nearest to the object side, which satisfies conditional formula (16), is L42.

[0164] Table 10 below shows the values ​​of each parameter in the tenth embodiment. (Table 10) 10th Example (Basic specifications) Magnification 9.96 Φ 42.00 Φe 25.00 2θ 7.50 2θ' 66.5 ER 15.455 TL 194.449 fo 80.049 fr 28.363 fe 14.114 fcom -140.612 Dm 41.909 nds 1.49782 νds 82.57 D1 188.466 D2 20.502 fe1 -14.092 rL 1477.865 NRC 2 Ne 4 (surface data) Surface number rd nd νd 1 58.275 5.783 1.49782 82.57 2 2170.730 0.200 3 41.473 4.578 1.49782 82.57 4 77.112 41.909 5 13.475 3.494 1.732828 45.55 6 -399.104 0.461 7 -65.211 2.947 1.85 23.00 8 10.150 15.313 9 (first intermediate image) ∞ 3.420 10 -43.257 1.081 1.670203 30.01 11 35.440 1.321 12 -55.783 4.660 1.932017 34.99 13 -10.881 4.181 14 -10.000 1.191 1.792792 32.44 15 -15.186 0.200 16 11.168 4.579 1.85 23.00 17 53.240 6.335 18 -11.212 3.000 1.85 23.00 19 12.924 0.874 20 -44.180 2.374 1.85 23.00 21 10.000 4.051 1.88 41.00 22 -13.150 0.200 23 14.877 4.473 1.77614 43.92 24 -10.000 1.000 1.85 23.00 25 71.238 23.666 26 -735.964 3.318 1.85 23.00 27 -20.218 0.200 28 17.597 3.152 1.85 23.00 29 69.780 2.112 30 -34.506 1.000 1.699325 47.04 31 10.045 15.350 32 (second intermediate image) ∞ 5.152 33 -58.169 4.853 1.88 41.00 34 -19.168 0.200 35 -85.696 1.000 1.85 23.00 36 13.999 9.923 1.650333 49.73 37 -33.536 0.200 38 19.099 6.698 1.88 41.00 39 1477.865 15.455 40 (eye point)

[0165] FIG. 20 is a diagram showing various aberrations in the observation optical system according to Example 10, and it is clear that various aberrations are well corrected and that the imaging performance is excellent.

[0166] According to each of the above-described embodiments, various aberrations can be corrected well, and a large-diameter observation optical system can be realized that achieves high magnification, compactness, and light weight while maintaining a wide actual field of view.

[0167] Next, the table of [Values ​​Corresponding to Conditional Expressions] is shown below. This table shows the values ​​corresponding to each of the conditional expressions (1) to (20) for all Examples (Examples 1 to 10). Condition (1) 0.060 <fe / TL<0.130 Condition (2) 0.040 <Dm / TL<0.350 Conditional expression (3) 80.00<νds Condition (4) 1.4300 <nds<1.5200 Conditional expression (5) 4.00<(-fcom) / fe<30.00 Condition (6) 4.00 <tanθ' / tanθ<30.00 Conditional expression (7) 1.00<(-fcom) / fo<3.50 Condition (8) 0.030 <ER / TL<0.120 Condition (9) 3.00 <fo / fe<8.00 Condition (10) 0.030 <fr / TL<0.160 Conditional expression (11) 0.40<(-fcom) / TL<1.20 Condition (12) 2.50 <fo / fr<10.00 Condition (13) 0.40 <fr / fe<2.50 Condition (14) 0.70 <D1 / TL<1.20 Condition (15) 0.030 <D2 / TL<0.200 Conditional expression (16) 0.90<(-fe1) / fe<10.00 Condition (17) 2.00 <rL / fe<200.00 Conditional expression (18) 0.55<Φe / Φ<1.50 Conditional formula (19) 1≦Nrc≦7 Condition (20) 4≦Ne≦8

[0168] [Conditional expression corresponding value] Conditional Expression 1st Example 2nd Example 3rd Example 4th Example (1) 0.078 0.085 0.078 0.085 (2) 0.094(d6) 0.089(d6) 0.098(d6) 0.093(d6) (3) 91.37(L12,13) ​​91.37(L12,13) ​​95.16(L12,13) ​​95.16(L12,13) (4) 1.45600(L12,13) ​​1.45600(L12,13) ​​1.43384(L12,13) ​​1.43384(L12,13) (5) 8.012 10.022 7.999 9.988 (6) 7.999 10.001 7.999 10.001 (7) 1.602 2.300 1.597 2.289 (8) 0.082 0.075 0.082 0.075 (9) 5.001 4.358 5.008 4.364 (10) 0.052 0.044 0.052 0.043 (11) 0.627 0.853 0.624 0.847 (12) 7.472 8.512 7.482 8.523 (13) 0.669 0.512 0.669 0.512 (14) 0.928 0.931 0.928 0.932 (15) 0.040(d31,32) 0.071(d31,32) 0.039(d31,32) 0.071(d31,32) (16) 4.587(L41) 4.833(L41) 4.587(L41) 4.833(L41) (17) 6.566 4.704 6.566 4.704 (18) 0.867 1.000 0.867 1.000 (19) 5 5 5 5 (20) 6 6 6 6 Conditional Expression 5th Example 6th Example 7th Example 8th Example (1) 0.078 0.085 0.082 0.093 (2) 0.095(d6) 0.090(d6) 0.254(d7) 0.081(d6) (3) 82.57(L12,13) ​​82.57(L12,13) ​​95.163(L12,13) ​​91.3748(L12,13) (4) 1.49782(L12,13) ​​1.49782(L12,13) ​​1.43384(L12,13) ​​1.45600(L12,13) (5) 8.009 10.018 10.015 10.069 (6) 7.999 10.013 9.995 10.071 (7) 1.602 2.299 2.413 2.620 (8) 0.082 0.075 0.070 0.075 (9) 5.001 4.358 4.151 3.843 (10) 0.052 0.044 0.044 0.049 (11) 0.627 0.852 0.817 0.934 (12) 7.472 8.512 7.606 7.275 (13) 0.669 0.512 0.546 0.528 (14) 0.928 0.931 0.948 0.932 (15) 0.040(d31,32) 0.071(d31,32) 0.048(d32,33) 0.076(d31,32) (16) 4.587(L41) 4.833(L41) 1.898(L41) 5.567(L41) (17) 6.566 4.704 7.159 4.311 (18) 0.862 1.000 0.786 1.110 (19) 5 5 2 5 (20) 6 6 5 6 Conditional Expression 9th Example 10th Example (1) 0.069 0.073 (2) 0.141(d4) 0.216(d4) (3) 82.57(L12) 82.57(L11,12) (4) 1.49782(L12) 1.49782(L11,12) (5) 10.000 9.963 (6) 10.013 10.003 (7) 1.851 1.757 (8) 0.078 0.079 (9) 5.404 5.672 (10) 0.071 0.146 (11) 0.693 0.723 (12) 5.263 2.822 (13) 1.027 2.010 (14) 0.971 0.969 (15) 0.063(d30,31) 0.105(d31,32) (16) 1.579(L43) 0.998(L42) (17) 141.926 104.711 (18) 0.662 0.595 (19) 2 2 (20) 4 4 However, in the above conditional expressions, (d6) and the like following a numerical value are the surface spacing numbers corresponding to that numerical value, and (L12) and the like are the lens numbers corresponding to that numerical value. [Explanation of symbols]

[0169] OS observation optical system OS1 First observation optical system OS2 Second observation optical system Objective lens R relay lens E eyepiece I1 1st intermediate image I2 Second intermediate image EP Eyepoint

Claims

1. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first intermediate image is formed between the objective optical system and the relay optical system, and a second intermediate image is formed between the relay optical system and the eyepiece optical system; An observation optical system that satisfies the following conditional expressions: 0.060<fe / TL<0.130 however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

2. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first observation optical system that forms a first intermediate image between the objective optical system and the relay optical system, and a second intermediate image between the relay optical system and the eyepiece optical system; a second observation optical system that is configured with the same lens components as the first observation optical system; The first observation optical system and the second observation optical system are arranged in parallel.

3. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first intermediate image is formed between the objective optical system and the relay optical system; forming a second intermediate image between the relay optical system and the eyepiece optical system; An observation optical system that satisfies the following conditional expressions: 0.040<Dm / TL<0.350 however, Dm: maximum air gap between lens surfaces in the observation optical system TL: total optical length of the observation optical system

4. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first intermediate image is formed between the objective optical system and the relay optical system, and a second intermediate image is formed between the relay optical system and the eyepiece optical system; An observation optical system in which at least one lens S among the lenses arranged in the objective optical system satisfies the following conditional expression: 80.00<νds however, νds: Abbe number of the lens S with respect to the d line

5. 5. The viewing optical system according to claim 1, wherein at least one lens S among the lenses arranged in the objective optical system satisfies the following conditional expression: however, 1.4300<nds<1.5200 however, nds: refractive index of the lens S with respect to the d line

6. 6. The observation optical system according to claim 4, wherein at least one lens S among the lenses arranged in the objective optical system is the positive lens closest to the object among the positive lenses included in the objective optical system.

7. 7. The observation optical system according to claim 1, wherein the lens closest to the object side of the observation optical system is a negative lens.

8. 8. The viewing optical system according to claim 2, which satisfies the following condition: 0.060<fe / TL<0.130 however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

9. 9. The viewing optical system according to claim 1, 2, or 4 to 8, which satisfies the following conditional expression: 0.040<Dm / TL<0.350 however, Dm: the maximum air gap between lens surfaces in the optical system TL: total optical length of the observation optical system

10. 10. The viewing optical system according to claim 1, wherein at least one lens S among the lenses arranged in the objective optical system satisfies the following conditional expression: 80.00<νds however, νds: Abbe number of the lens S with respect to the d line

11. 11. The viewing optical system according to claim 1, which satisfies the following condition: 4.00<(-fcom) / fe<30.00 however, fcom: composite focal length of the objective optical system and the relay optical system fe: focal length of the eyepiece optical system

12. 12. The viewing optical system according to claim 1, which satisfies the following condition: 4.00<tanθ' / tanθ<30.00 however, 2θ: actual field of view of the observation optical system, unit [°] 2θ': apparent field of view of the observation optical system, unit [°]

13. 13. The viewing optical system according to claim 1, which satisfies the following condition: 1.00<(-fcom) / fo<3.50 however, fcom: composite focal length of the objective optical system and the relay optical system fo: focal length of the objective optical system

14. 14. The viewing optical system according to claim 1, which satisfies the following condition: 0.030<ER / TL<0.120 however, ER: eye relief of the observation optical system TL: total optical length of the observation optical system

15. 15. The viewing optical system according to claim 1, which satisfies the following condition: 3.00<fo / fe<8.00 however, fo: focal length of the objective optical system fe: focal length of the eyepiece optical system

16. 16. The viewing optical system according to claim 1, which satisfies the following condition: 0.030<fr / TL<0.160 however, fr: focal length of the relay optical system TL: total optical length of the observation optical system

17. 17. The viewing optical system according to claim 1, which satisfies the following condition: 0.40<(-fcom) / TL<1.20 however, fcom: composite focal length of the objective optical system and the relay optical system TL: total optical length of the observation optical system

18. 18. The viewing optical system according to claim 1, which satisfies the following condition: 2.50<fo / fr<10.00 however, fo: focal length of the objective optical system fr: focal length of the relay optical system

19. 19. The viewing optical system according to claim 1, which satisfies the following condition: 0.40<fr / fe<2.50 however, fr: focal length of the relay optical system fe: focal length of the eyepiece optical system

20. 20. The viewing optical system according to claim 1, which satisfies the following condition: 0.70<D1 / TL<1.20 however, D1: the distance from the object side of the second lens component located closest to the object in the objective optical system to the observation side of the eyepiece optical system TL: total optical length of the observation optical system The lens component refers to a single lens or a cemented lens.

21. 21. The viewing optical system according to claim 1, which satisfies the following condition: 0.030<D2 / TL<0.200 however, D2: distance from the most observation side of the relay optical system to the most object side of the eyepiece optical system TL: total optical length of the observation optical system

22. 22. The viewing optical system according to claim 1, wherein the eyepiece optical system has a negative lens and satisfies the following condition: 1<f<1 / f<2 / ... 0.90<(-fe1) / fe<10.00 however, fe1: the focal length of the negative lens in the eyepiece optical system that is closest to the object fe: focal length of the eyepiece optical system

23. 23. The viewing optical system according to claim 1, which satisfies the following condition: 2.00<rL / fe<200.00 however, rL: radius of curvature of the lens surface of the eyepiece optical system closest to the observation side fe: focal length of the eyepiece optical system

24. 24. The viewing optical system according to claim 1, which satisfies the following condition: 0.55<Φe / Φ<1.50 however, Φe: maximum effective diameter of the eyepiece optical system Φ: diameter of the objective optical system

25. 25. The viewing optical system according to claim 1, wherein the relay optical system has a cemented lens, and the following condition is satisfied: 1<f<1<f<1 / f<2 / ... 1≦Nrc≦7 however, Nrc: number of cemented lenses in the relay optical system

26. 26. The viewing optical system according to claim 1, which satisfies the following condition: 4≦Ne≦8 however, Ne: number of lenses in the eyepiece optical system

27. An optical instrument comprising the observation optical system according to any one of claims 1 to 26.

28. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first intermediate image is formed between the objective optical system and the relay optical system, and a second intermediate image is formed between the relay optical system and the eyepiece optical system; A method for manufacturing an observation optical system configured to satisfy the following conditional expressions: 0.060<fe / TL<0.130 however, fe: focal length of the eyepiece optical system TL: total optical length of the observation optical system

29. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first observation optical system that forms a first intermediate image between the objective optical system and the relay optical system, and a second intermediate image between the relay optical system and the eyepiece optical system; a second observation optical system that is configured with the same lens components as the first observation optical system; A manufacturing method for an observation optical system, in which the first observation optical system and the second observation optical system are arranged in parallel.

30. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first intermediate image is formed between the objective optical system and the relay optical system, and a second intermediate image is formed between the relay optical system and the eyepiece optical system; A method for manufacturing an observation optical system configured to satisfy the following conditional expressions: 0.040<Dm / TL<0.350 however, Dm: maximum air gap between lens surfaces in the observation optical system TL: total optical length of the observation optical system

31. The optical system has, in order from the object side, an objective optical system, an erecting optical system, and an eyepiece optical system, the erecting optical system being a relay optical system; a first intermediate image is formed between the objective optical system and the relay optical system, and a second intermediate image is formed between the relay optical system and the eyepiece optical system; A manufacturing method of an observation optical system, in which at least one lens S among the lenses arranged in the objective optical system is configured to satisfy the following conditional expression: 80.00<νds however, νds: Abbe number of the lens S with respect to the d line

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