Optical system, optical device, and method for manufacturing optical system

Abstract

This optical system is configured to be provided with: a first optical system comprising, in order from the object side, a front-side lens group having negative refractive power, an optical path branching member having a branching surface that transmits a part of incident light and reflects at least a part different from the part of the incident light, and a first rear-side lens group on which first light that is at least a part of light reflected by the branching surface is incident; and a second optical system comprising, in order from the object side, a front-side lens group, an optical path branching member, and a second rear-side lens group on which second light that is at least a part of light transmitted through the branching surface is incident, the second optical system having an entire system focal length different from the entire system focal length of the first optical system.

Description

Optical system, optical device, and method for manufacturing optical system

[0001] The present disclosure relates to optical systems, optical devices, and methods for manufacturing optical systems.

[0002] An optical device has been proposed that separates light from a subject that has passed through a photographic lens into visible light and infrared light, and forms a visible light image and an infrared light image at different positions (see, for example, Patent Document 1).

[0003] JP 2010-102281 A

[0004] The optical system of the present disclosure comprises, in order from the object side, a first optical system having a front lens group having negative refractive power, an optical path branching element having a branching surface that transmits a portion of incident light and reflects at least a portion different from the portion of the incident light, and a first rear lens group into which first light, which is at least a portion of the light reflected at the branching surface, is incident, and a second optical system having, in order from the object side, the front lens group, the optical path branching element, and a second rear lens group into which second light, which is at least a portion of the light transmitted at the branching surface, is incident, and the second optical system has an overall system focal length different from that of the first optical system.

[0005] The method for manufacturing an optical system disclosed herein is a method for manufacturing an optical system that has a branching surface that transmits a portion of incident light and reflects at least a portion different from the portion of the incident light, and that images a first light that is at least a portion of the light reflected by the branching surface and a second light that is at least a portion of the light that is transmitted by the branching surface, respectively. The method comprises: arranging a first optical system to include, in order from the object side, a front lens group having negative refractive power, an optical path branching member having the branching surface, and a first rear lens group into which the first light is incident; arranging a second optical system to include, in order from the object side, a front lens group, the optical path branching member, and a second rear lens group into which the second light is incident; and configuring the second optical system to have an overall system focal length different from that of the first optical system.

[0006] FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an optical system according to this embodiment. FIG. 2 is a cross-sectional view of a first optical system included in an optical system according to a first example. FIG. 3 is a diagram illustrating various aberrations of the first optical system included in the optical system according to the first example. FIG. 4 is a cross-sectional view of a second optical system included in the optical system according to the first example. FIG. 5 is a diagram illustrating various aberrations of the second optical system included in the optical system according to the first example. FIG. 6 is a cross-sectional view of a first optical system included in an optical system according to a second example. FIG. 7 is a diagram illustrating various aberrations of the first optical system included in the optical system according to the second example. FIG. 8 is a cross-sectional view of a second optical system included in the optical system according to the second example. FIG. 9 is a diagram illustrating various aberrations of the second optical system included in the optical system according to the second example. FIG. 10 is a cross-sectional view of a first optical system included in an optical system according to a third example. FIG. 11 is a diagram illustrating various aberrations of the first optical system included in the optical system according to the third example. FIG. 12 is a cross-sectional view of a second optical system included in the optical system according to the third example. FIG. 13 is a diagram showing various aberrations of the second optical system included in the optical system of Example 3. FIG. 14 is a cross-sectional view of the first optical system included in the optical system of Example 4. FIG. 15 is a diagram showing various aberrations of the first optical system included in the optical system of Example 4. FIG. 16 is a cross-sectional view of the second optical system included in the optical system of Example 4. FIG. 17 is a diagram showing various aberrations of the second optical system included in the optical system of Example 4. FIG. 18 is a cross-sectional view of the first optical system included in the optical system of Example 5. FIG. 19 is a diagram showing various aberrations of the first optical system included in the optical system of Example 5. FIG. 20 is a cross-sectional view of the second optical system included in the optical system of Example 5. FIG. 21 is a diagram showing various aberrations of the second optical system included in the optical system of Example 5. FIG. 22 is a cross-sectional view of the first optical system included in the optical system of Example 6. FIG. 23 is a diagram showing various aberrations of the first optical system included in the optical system of Example 6. FIG. 24 is a cross-sectional view of the second optical system included in the optical system of Example 6. Fig. 25 is a diagram showing various aberrations of the second optical system included in the optical system of Example 6. Fig. 26 is a schematic diagram illustrating the overall configuration of the optical system of Example 7. Fig. 27 is a cross-sectional view of the first optical system included in the optical system of Example 7. Fig. 28 is a diagram showing various aberrations of the first optical system included in the optical system of Example 7. Fig. 29 is a cross-sectional view of the second optical system included in the optical system of Example 7. Fig. 30 is a diagram showing various aberrations of the second optical system included in the optical system of Example 7. Fig. 31 is a schematic diagram illustrating the overall configuration of the optical system of Example 8.FIG. 32 is a cross-sectional view of the first optical system included in the optical system of Example 8-1. FIG. 33 is a diagram showing various aberrations of the first optical system included in the optical system of Example 8-1. FIG. 34 is a cross-sectional view of the second optical system included in the optical system of Example 8-1. FIG. 35 is a diagram showing various aberrations of the second optical system included in the optical system of Example 8-1. FIG. 36 is a cross-sectional view of the first optical system included in the optical system of Example 8-2. FIG. 37 is a diagram showing various aberrations of the first optical system included in the optical system of Example 8-2. FIG. 38 is a cross-sectional view of the second optical system included in the optical system of Example 8-2. FIG. 39 is a diagram showing various aberrations of the second optical system included in the optical system of Example 8-2. FIG. 40 is a cross-sectional view of the second optical system included in the optical system of Example 9-1. FIG. 41 is a diagram showing various aberrations of the second optical system included in the optical system of Example 9-1. FIG. 42 is a cross-sectional view of the second optical system included in the optical system of Example 9-2. FIG. 43 is a diagram showing various aberrations of the second optical system included in the optical system of Example 9-2. FIG. 44 is a cross-sectional view of the first optical system included in the optical system of Example 10. FIG. 45 is a diagram showing various aberrations of the first optical system included in the optical system of Example 10. FIG. 46 is a cross-sectional view of the second optical system included in the optical system of Example 10. FIG. 47 is a diagram showing various aberrations of the second optical system included in the optical system of Example 10. FIG. 48 is a schematic diagram of an optical device including the optical system of this embodiment. FIG. 49 is a diagram explaining an example of the operation of a drive unit in the optical device of this embodiment. FIG. 50 is a diagram showing an example of image information generated by the optical device of this embodiment. FIG. 51 is a flowchart showing an outline of a method for manufacturing the optical system of this embodiment.

[0007] An optical system, an optical device, and a method for manufacturing an optical system according to embodiments of the present application will be described below.

[0008] FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an optical system according to this embodiment.

[0009] The optical system 1 of this embodiment has a first optical system OS1 including, in order from the object side, a front lens group GF, an optical path branching member OB having a branching surface BP1, and a first rear lens group GR1 onto which light incident on the front lens group GF and the optical path branching member OB and reflected by the branching surface BP1 is incident. The optical system 1 of this embodiment also has a second optical system OS2 including, in order from the object side, the front lens group GF, the optical path branching member OB, and a second rear lens group GR2 onto which light incident on the front lens group GF and the optical path branching member OB and reflected by the branching surface BP1 is incident. The front lens group GF has negative refractive power.

[0010] In FIG. 1, the first optical axis AX1 of the first optical system OS1 and the second optical axis AX2 of the second optical system OS2 are depicted so as not to overlap with each other on the object side of the splitting surface BP for the sake of explanation.

[0011] In the optical system 1 of this embodiment, light emitted from the front lens group GF is incident on the optical path branching member OB. The optical path branching member OB is a cube-type beam splitter (prism) having a branching surface BP1 that transmits a portion of the incident light and reflects at least a portion different from the portion of the incident light. The optical path branching member OB may also be a flat-plate beam splitter (half mirror) having the branching surface BP1.

[0012] In the first optical system OS1 of the optical system 1 of this embodiment, light that is emitted from the front lens group GF and enters the optical path branching member OB is reflected by the branching surface BP1, enters the first rear lens group GR1, and forms an image on the first image plane I1. In the second optical system OS2 of the optical system 1 of this embodiment, light that is emitted from the front lens group GF and enters the optical path branching member OB is transmitted by the branching surface BP1, enters the second rear lens group GR2, and forms an image on the second image plane I2.

[0013] In the optical system 1 of this embodiment, the second optical system OS2 has an overall focal length that is different from the overall focal length of the first optical system OS1.

[0014] In the optical system 1 of this embodiment, the front lens group GF has a negative refractive power, which makes the angle of view of the wide-angle optical system, which has the shorter overall focal length of the first optical system OS1 or the second optical system OS2, sufficiently wide, and makes the magnification ratio of the telephoto optical system, which has the longer overall focal length of the first optical system OS1 or the second optical system OS2, sufficiently large, while allowing the incident light to be properly imaged by each optical system.

[0015] It is preferable that the optical system 1 of this embodiment satisfy the following condition: 1.20<fB / fA<13.00 (1), where fB is the longer of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2, and fA is the shorter of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2.

[0016] Conditional expression (1) defines the ratio between the total focal length of the telephoto-side optical system and the total focal length of the wide-angle-side optical system. By satisfying conditional expression (1), the optical system 1 of this embodiment can adequately correct various aberrations while making the angle of view of the wide-angle-side optical system sufficiently wide and the magnification ratio of the telephoto-side optical system sufficiently large.

[0017] In the optical system 1 of this embodiment, if the value of conditional expression (1) exceeds the upper limit, it is not possible to sufficiently widen the angle of view of the wide-angle optical system and to sufficiently increase the magnification of the telephoto optical system.

[0018] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit value of conditional expression (1) to 13.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (1) to 12.55, 12.05, 11.62, 11.16, 10.70, or even 10.00.

[0019] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (1) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as axial chromatic aberration, chromatic aberration of magnification, and distortion.

[0020] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (1) to 1.20. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (1) to 1.35, 1.50, 1.65, 1.80, 1.95, or even 2.00.

[0021] It is preferable that the optical system 1 of this embodiment satisfy the following condition (2): 0.20<-fF / fA<10.00, where fF is the focal length of the front lens group GF, and fA is the shorter of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2.

[0022] Conditional expression (2) defines the ratio between the focal length of the front lens group GF and the focal length of the entire wide-angle side optical system. By satisfying conditional expression (2), the optical system 1 of this embodiment can appropriately correct various aberrations.

[0023] In the optical system 1 of this embodiment, if the value of conditional expression (2) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion.

[0024] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit value of conditional expression (2) to 10.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (2) to 9.60, 9.20, 8.805, 8.40, 8.00, or even 7.00.

[0025] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (2) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion.

[0026] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (2) to 0.20. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.26, 0.32, 0.38, 0.44, 0.50, or even 1.00.

[0027] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (3): 0.05<-fF / fB<3.50, where fF is the focal length of the front lens group GF, and fB is the longer of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2.

[0028] Conditional expression (3) defines the ratio between the focal length of the front lens group GF and the focal length of the telephoto side optical system. By satisfying conditional expression (3), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the overall optical length.

[0029] In the optical system 1 of this embodiment, if the value of conditional expression (3) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0030] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (3) to 3.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (3) to 3.30, 3.10, 2.90, 2.70, 2.50, or even 2.00.

[0031] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (3) is below the lower limit, the negative power of the front lens group GF becomes too strong, the overall focal length of the telephoto-side optical system becomes long, and the overall optical length of the telephoto-side optical system increases, making it difficult to appropriately correct various aberrations such as field curvature, astigmatism, axial chromatic aberration, and chromatic aberration of magnification.

[0032] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (3) to 0.05. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.06, 0.07, 0.08, 0.09, 0.10, or even 0.20.

[0033] It is preferable that the optical system 1 of this embodiment satisfy the following condition (4): 3.50<-f1 / fA<50.30, where f1 is the focal length of the lens in the front lens group GF that is located closest to the object, and fA is the shorter of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2.

[0034] Conditional expression (4) defines the ratio between the focal length of the lens in the front lens group GF located closest to the object and the focal length of the wide-angle side optical system. By satisfying conditional expression (4), the optical system 1 of this embodiment can appropriately correct various aberrations while preventing the lens located closest to the object in the front lens group GF from becoming too large.

[0035] In the optical system 1 of this embodiment, if the value of conditional expression (4) exceeds the upper limit, the lens positioned closest to the object in the front lens group GF becomes large, making it difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion.

[0036] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (4) to 50.30. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (4) to 49.00, 46.00, 43.00, 40.00, or even 36.00.

[0037] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (4) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion.

[0038] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (4) to 3.50. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (4) to 3.74, 3.98, 4.22, 4.46, 4.70, or even 6.50.

[0039] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (5): 0.25<-f1 / fB<15.00, where f1 is the focal length of the lens in the front lens group GF that is located closest to the object, and fB is the longer of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2.

[0040] Conditional expression (5) defines the ratio between the focal length of the lens in the front lens group GF located closest to the object and the focal length of the telephoto side optical system. By satisfying conditional expression (5), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the size of the lens located closest to the object in the front lens group GF and an increase in the overall optical length.

[0041] In the optical system 1 of this embodiment, if the value of conditional expression (5) exceeds the upper limit, the lens positioned closest to the object in the front lens group GF becomes large, making it difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0042] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (5) to 15.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 14.40, 13.80, 13.20, 12.60, 12.00, or even 11.50.

[0043] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (5) is below the lower limit, the negative power of the front lens group GF becomes too strong, the overall focal length of the telephoto-side optical system becomes long, and the overall optical length of the telephoto-side optical system increases, making it difficult to appropriately correct various aberrations such as field curvature, astigmatism, axial chromatic aberration, and chromatic aberration of magnification.

[0044] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (5) to 0.25. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.30, 0.35, 0.40, 0.45, 0.50, or even 1.00.

[0045] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (6): 0.04<-D12 / f1<1.50, where D12 is the distance on the optical axis between the image-side lens surface of the lens located closest to the object in the front lens group GF and the object-side lens surface of the lens located adjacent to the image-side lens located closest to the object in the front lens group GF, and f1 is the focal length of the lens located closest to the object in the front lens group GF.

[0046] Conditional expression (6) defines the ratio of the axial distance between the lens located closest to the object in the front lens group GF and the lens located adjacent to that lens on the image plane side, to the focal length of the lens located closest to the object in the front lens group GF. By satisfying conditional expression (6), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the size of the lens located closest to the object in the front lens group GF and an increase in the overall optical length.

[0047] In the optical system 1 of this embodiment, if the value of conditional expression (6) exceeds the upper limit, the lens in the front lens group GF that is located closest to the object will become larger, the overall optical length of the wide-angle and telephoto optical systems will increase, and it will become difficult to appropriately correct various aberrations such as field curvature, coma, and chromatic aberration of magnification.

[0048] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (6) to 1.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (6) to 1.44, 1.38, 1.32, 1.26, 1.20, or even 0.85.

[0049] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (6) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as curvature of field, coma, and chromatic aberration of magnification.

[0050] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (6) to 0.04. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.05, 0.06, 0.07, 0.08, 0.09, or even 0.11.

[0051] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (7): 0.30<TLB / TLA<3.50, where TLB is the total optical length of the optical system having the longer total system focal length out of the first optical system OS1 and the second optical system OS2, and TLA is the total optical length of the optical system having the shorter total system focal length out of the first optical system OS1 and the second optical system OS2.

[0052] Conditional expression (7) defines the ratio between the total optical length of the telephoto-side optical system and the total optical length of the wide-angle-side optical system. By satisfying conditional expression (7), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the total optical length.

[0053] In the optical system 1 of this embodiment, if the value of conditional expression (7) exceeds the upper limit, the total optical length of the telephoto-side optical system increases, and it becomes difficult to appropriately correct various aberrations such as curvature of field, astigmatism, and distortion in the wide-angle-side optical system.

[0054] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (7) to 3.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (7) to 3.30, 3.10, 2.90, 2.70, 2.50, or even 2.25.

[0055] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (7) falls below the lower limit, the total optical length of the wide-angle side optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and coma in the wide-angle side optical system.

[0056] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (7) to 0.30. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (7) to 0.38, 0.46, 0.54, 0.62, 0.70, or even 0.85.

[0057] It is preferable that the optical system 1 of this embodiment satisfy the following condition (8): 0.30<-(r12+r11) / (r12-r11)<4.70, where r12 is the radius of curvature of the image-side lens surface of the lens located closest to the object in the front lens group GF, and r11 is the radius of curvature of the object-side lens surface of the lens located closest to the object in the front lens group GF.

[0058] Conditional expression (8) defines the shape factor of the lens in the front lens group GF that is located closest to the object. By satisfying conditional expression (8), the optical system 1 of this embodiment can appropriately correct various aberrations, such as curvature of field, astigmatism, distortion, and coma.

[0059] In the optical system 1 of this embodiment, if the value of conditional expression (8) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion.

[0060] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (8) to 4.70. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (8) to 4.60, 4.50, 4.40, 4.30, 4.20, or even 3.50.

[0061] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (8) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and coma.

[0062] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (8) to 0.30. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.34, 0.38, 0.42, 0.46, 0.50, or even 0.90.

[0063] It is preferable that the optical system 1 of this embodiment satisfy the following condition (9): 0.10<(r21+r12) / (r21-r12)<3.30, where r21 is the radius of curvature of the object-side lens surface of the lens located adjacent to the image plane side of the lens located closest to the object in the front lens group GF, and r12 is the radius of curvature of the image plane side lens surface of the lens located closest to the object in the front lens group GF.

[0064] Conditional expression (9) defines the shape factor of an air lens disposed between the lens closest to the object in the front lens group GF and the lens adjacent to the lens closest to the object in the front lens group GF on the image plane side. By satisfying conditional expression (9), the optical system 1 of this embodiment can appropriately correct various aberrations, such as curvature of field and astigmatism.

[0065] In the optical system 1 of this embodiment, if the value of conditional expression (9) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0066] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (9) to 3.30. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (9) to 3.00, 2.90, 2.60, 2.30, or even 2.00.

[0067] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (9) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0068] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (9) to 0.10. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.14, 0.18, 0.22, 0.26, or even 0.29.

[0069] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (10): 0.30 < D12 / fA < 11.30, where D12 is the distance on the optical axis between the image-side lens surface of the lens located closest to the object in the front lens group GF and the object-side lens surface of the lens located adjacent to the image-side lens located closest to the object in the front lens group GF, fA is the shorter of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS1.

[0070] Conditional expression (10) defines the ratio of the axial distance between the lens in the front lens group GF located closest to the object and the lens located adjacent to that lens on the image plane side to the focal length of the wide-angle side optical system. By satisfying conditional expression (10), optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the overall optical length.

[0071] In the optical system 1 of this embodiment, if the value of conditional expression (10) exceeds the upper limit, the total optical length of the wide-angle side optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature and coma.

[0072] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (10) to 11.30. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (10) to 10.80, 10.30, 9.80, 9.30, 8.85, or even 8.40.

[0073] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (10) falls below the lower limit, it becomes difficult to appropriately correct various aberrations including coma.

[0074] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (10) to 0.30. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (10) to 0.35, 0.40, 0.45, 0.50, 0.55, or even 1.00.

[0075] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (11): 0.07 < D12 / fB < 4.30, where D12 is the distance on the optical axis between the image-side lens surface of the lens located closest to the object in the front lens group GF and the object-side lens surface of the lens located adjacent to the image-side lens located closest to the object in the front lens group GF, and fB is the longer of the overall focal length of the first optical system OS1 and the overall focal length of the second optical system OS2.

[0076] Conditional expression (11) defines the ratio of the axial distance between the lens in the front lens group GF located closest to the object and the lens located adjacent to that lens on the image plane side, to the total focal length of the telephoto-side optical system. By satisfying conditional expression (11), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the overall optical length.

[0077] In the optical system 1 of this embodiment, if the value of conditional expression (11) exceeds the upper limit, the total optical length of the telephoto side optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature and coma.

[0078] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (11) to 4.30. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (11) to 4.05, 3.80, 3.55, 3.30, 3.00, or even 2.70.

[0079] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (11) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as coma, axial chromatic aberration, and chromatic aberration of magnification.

[0080] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (11) to 0.07. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (11) to 0.08, 0.09, 0.11, 0.12, 0.13, or even 0.35.

[0081] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (12): 1.20<ωA / ωB<15.00, where ωA is the half angle of view of the optical system having the shorter total focal length out of the first optical system OS1 and the second optical system OS2, and ωB is the half angle of view of the optical system having the longer total focal length out of the first optical system OS1 and the second optical system OS2.

[0082] Conditional expression (12) defines the ratio between the half angle of view of the wide-angle side optical system and the half angle of view of the telephoto side optical system. By satisfying conditional expression (12), the optical system 1 of this embodiment can appropriately correct various aberrations while making the angle of view of the wide-angle side optical system sufficiently wide and making the magnification ratio of the telephoto side optical system sufficiently large.

[0083] In the optical system 1 of this embodiment, if the value of conditional expression (12) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion in the wide-angle-side optical system, and it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, axial chromatic aberration, and chromatic aberration of magnification in the telephoto-side optical system.

[0084] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (12) to 15.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (12) to 14.60, 14.20, 13.80, 13.40, 13.00, or even 11.40.

[0085] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (12) is below the lower limit, it is not possible to sufficiently increase the magnification ratio of the telephoto optical system while sufficiently widening the angle of view of the wide-angle optical system.

[0086] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (12) to 1.20. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (12) to 1.31, 1.42, 1.53, 1.64, 1.75, or even 2.00.

[0087] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (13): 0.20 < fpA / fpB < 2.50, where fpA is the composite focal length of the positive lens component arranged continuously from the positive lens component arranged closest to the object to the positive lens component arranged continuously to the image plane side in the rear lens group of either the first rear lens group GR1 or the second rear lens group GR2, whichever is the optical system having the shorter total system focal length, the first optical system OS1 or the second optical system OS2, and fpB is the composite focal length of the positive lens component arranged continuously from the positive lens component arranged closest to the object to the positive lens component arranged continuously to the image plane side in the rear lens group of either the first rear lens group GR1 or the second rear lens group GR2, whichever is the optical system having the longer total system focal length.

[0088] Conditional expression (13) defines the ratio between the composite focal length of the positive lens component arranged in succession from the positive lens component arranged closest to the object in the rear lens group included in the wide-angle side optical system to the positive lens component arranged in succession from the positive lens component arranged closest to the object in the rear lens group included in the telephoto side optical system, and the composite focal length of the positive lens component arranged in succession from the positive lens component arranged closest to the object in the rear lens group included in the telephoto side optical system. By satisfying conditional expression (13), the optical system 1 of this embodiment can appropriately correct various aberrations.

[0089] In the optical system 1 of this embodiment, if the value of conditional expression (13) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0090] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (13) to 2.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (13) to 2.40, 2.30, 2.20, 2.10, or even 2.00.

[0091] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (13) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0092] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (13) to 0.20. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (13) to 0.24, 0.28, 0.32, 0.36, or even 0.40.

[0093] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (14): 0.33 < |fRB / fRA| < 65.00, where fRB is the focal length of the rear lens group of the first rear lens group GR1 or the second rear lens group GR2 that is included in the optical system having the longer total system focal length, either the first optical system OS1 or the second optical system OS2, and fRA is the focal length of the rear lens group of the first rear lens group GR1 or the second rear lens group GR2 that is included in the optical system having the shorter total system focal length, either the first optical system OS1 or the second optical system OS2.

[0094] Conditional expression (14) defines the ratio between the focal length of the rear lens group included in the telephoto-side optical system and the focal length of the rear lens group included in the wide-angle-side optical system. By satisfying conditional expression (14), the optical system 1 of this embodiment can appropriately correct various aberrations.

[0095] In the optical system 1 of this embodiment, if the value of conditional expression (14) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0096] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (14) to 65.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (14) to 63.70, 62.40, 61.10, 59.80, 58.50, or even 50.50.

[0097] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (14) falls below the lower limit, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0098] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (14) to 0.33. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (14) to 0.39, 0.45, 0.51, 0.57, 0.63, or even 0.75.

[0099] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (15): 7.00<TLB / fA<110.00, where TLB is the total optical length of the optical system having the longer total system focal length out of the first optical system OS1 and the second optical system OS2, and fA is the shorter total system focal length out of the total system focal lengths of the first optical system OS1 and the second optical system OS2.

[0100] Conditional expression (15) defines the ratio between the total optical length of the telephoto-side optical system and the total focal length of the wide-angle-side optical system. By satisfying conditional expression (15), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the total optical length.

[0101] In the optical system 1 of this embodiment, if the value of conditional expression (15) exceeds the upper limit, the total optical length of the telephoto side optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and coma.

[0102] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit value of conditional expression (15) to 110.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (15) to 107.50, 105.00, 102.50, 100.00, or even 97.50.

[0103] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (15) falls below the lower limit, it becomes difficult to appropriately correct various aberrations, such as distortion, curvature of field, and astigmatism, particularly in the wide-angle optical system.

[0104] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (15) to 7.00. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (15) to 8.16, 9.32, 10.48, 11.64, 12.80, or even 20.00.

[0105] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (16): 0.30<TLA / fB<20.50, where TLA is the total optical length of either the first optical system OS1 or the second optical system OS2, whichever has the shorter total system focal length, and fB is the longer total system focal length of either the first optical system OS1 or the second optical system OS2.

[0106] Conditional expression (16) defines the ratio between the total optical length of the wide-angle side optical system and the total focal length of the telephoto side optical system. By satisfying conditional expression (16), the optical system 1 of this embodiment can appropriately correct various aberrations while suppressing an increase in the total optical length.

[0107] In the optical system 1 of this embodiment, if the value of conditional expression (16) exceeds the upper limit, the total optical length of the wide-angle side optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and coma.

[0108] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (16) to 20.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (16) to 19.80, 19.10, 18.40, 17.80, or even 16.50.

[0109] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (16) falls below the lower limit, it becomes difficult to appropriately correct various aberrations, such as field curvature, astigmatism, axial chromatic aberration, and chromatic aberration of magnification, particularly in the telephoto side optical system.

[0110] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (16) to 0.30. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (16) to 0.35, 0.40, 0.45, 0.50, 0.55, or even 2.05.

[0111] It is preferable that the optical system 1 of this embodiment satisfies the following conditional expression (17): 1.70<nd1<2.01 where, nd1: refractive index for the d-line of the lens arranged closest to the object in the front lens group GF.

[0112] Conditional expression (17) defines the refractive index for the d-line of the lens arranged closest to the object in the front lens group GF. By satisfying conditional expression (17), the optical system 1 of this embodiment can appropriately correct various aberrations.

[0113] In the optical system 1 of this embodiment, if the value of conditional expression (17) exceeds the upper limit, the degree of freedom in selecting the glass material used for the lens decreases, making color correction difficult.

[0114] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (17) to 2.01. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (17) to 1.97, 1.93, 1.88, 1.84, or even 1.80.

[0115] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (17) falls below the lower limit, the power of the lens arranged closest to the object in the front lens group GF will be weak, making it difficult to correct field curvature, particularly in the wide-angle optical system.

[0116] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (17) to 1.70. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (17) to 1.71.

[0117] It is preferable that the optical system 1 of this embodiment satisfies the following conditional expression (18): 1.50<nd2<2.01 where nd2 is the refractive index for the d-line of the lens arranged adjacent to the image plane side of the lens arranged closest to the object side in the front lens group GF.

[0118] Conditional expression (18) defines the refractive index for the d-line of the lens arranged adjacent to the lens arranged closest to the object in the front lens group GF on the image plane side. By satisfying conditional expression (18), the optical system 1 of this embodiment can appropriately correct various aberrations.

[0119] In the optical system 1 of this embodiment, if the value of conditional expression (18) exceeds the upper limit, the degree of freedom in selecting the glass material used for the lens decreases, making color correction difficult.

[0120] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (18) to 2.01. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (18) to 1.95, 1.89, 1.82, 1.76, or even 1.70.

[0121] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (18) falls below the lower limit, the power of the lens arranged adjacent to the image plane side of the lens arranged closest to the object in the front lens group GF will be weakened, making it difficult to correct field curvature, particularly in the wide-angle side optical system.

[0122] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (18) to 1.50. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (18) to 1.55.

[0123] It is preferable that the optical system 1 of this embodiment satisfies the following conditional expression (19): 1.55<ndaveF<2.01 where, ndaveF: average refractive index for the d-line of the lenses in the front lens group GF.

[0124] Conditional expression (19) defines the average refractive index of the lenses in the front lens group GF with respect to the d-line. By satisfying conditional expression (19), the optical system 1 of this embodiment can appropriately correct various aberrations.

[0125] In the optical system 1 of this embodiment, if the value of conditional expression (19) exceeds the upper limit, the degree of freedom in selecting the glass material used for the lenses of the front lens GF decreases, making color correction difficult.

[0126] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (19) to 2.01. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (19) to 1.95, 1.89, 1.83, 1.77, or even 1.71.

[0127] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (19) falls below the lower limit, it becomes difficult to correct various aberrations.

[0128] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (19) to 1.55. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (19) to 1.55, 1.57, 1.59, 1.61, 1.63, or even 1.65.

[0129] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (20): 45°<ωA<120°, where ωA is the half angle of view of either the first optical system OS1 or the second optical system OS2, whichever has the shorter overall focal length.

[0130] Conditional expression (20) defines the half angle of view of the wide-angle side optical system. By satisfying conditional expression (20), the optical system 1 of this embodiment can satisfactorily correct various aberrations such as field curvature, astigmatism, and distortion, while making the angle of view of the wide-angle side optical system sufficiently wide.

[0131] In the optical system 1 of this embodiment, if the value of conditional expression (20) exceeds the upper limit, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and distortion.

[0132] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit value of conditional expression (20) to 120°. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (20) to 118°, 115°, 110°, 105°, or even 100°.

[0133] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (20) is below the lower limit, the angle of view of the wide-angle optical system cannot be made sufficiently wide.

[0134] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (20) to 45°. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (20) to 50°, 55°, 60°, 65°, or even 70°.

[0135] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (21): 3°<ωB<30°, where ωB is the half angle of view of either the first optical system OS1 or the second optical system OS2, whichever has the longer overall focal length.

[0136] Conditional expression (21) defines the half angle of view of the telephoto-side optical system. By satisfying conditional expression (21), the optical system 1 of this embodiment can satisfactorily correct chromatic aberration while sufficiently increasing the magnification ratio of the telephoto-side optical system.

[0137] In the optical system 1 of this embodiment, if the value of conditional expression (21) exceeds the upper limit, the magnification ratio of the telephoto side optical system cannot be made sufficiently large.

[0138] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit value of conditional expression (21) to 30°. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (21) to 28°, 26°, 24°, 22°, or even 20°.

[0139] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (21) is below the lower limit, chromatic aberration cannot be appropriately corrected.

[0140] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (21) to 3°. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (21) to 4°, 5°, 6°, 7°, or even 8°.

[0141] It is preferable that the optical system 1 of this embodiment satisfy the following conditional expression (22): 0.10 < Wi / (1-Wi) ≦ 1.00, where Wi: the reflectance of the branching surface BP when the optical path of either the first optical system OS1 or the second optical system OS2, which has a shorter focal length overall, is reflected by the branching surface BP, and the transmittance of the branching surface BP when the optical path of either the first optical system OS1 or the second optical system OS2, which has a shorter focal length overall, is transmitted by the branching surface BP.

[0142] Conditional expression (22) defines the ratio between the reflectance or transmittance when the optical path of the wide-angle side optical system is reflected or transmitted by the splitting surface BP and the proportion of the optical path of the wide-angle side optical system that is not reflected or transmitted when the optical path of the wide-angle side optical system is reflected or transmitted by the splitting surface BP. By satisfying conditional expression (22), the optical system 1 of this embodiment can keep the difference in brightness between the image formed on the image plane by the wide-angle side optical system with a smaller F-number and the image formed on the image plane by the telephoto side optical system with a larger F-number within an appropriate range.

[0143] In the optical system 1 of this embodiment, if the value of conditional expression (22) exceeds the upper limit, the image formed on the image plane by the telephoto-side optical system becomes too dark.

[0144] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit value of conditional expression (22) to 1.00. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (22) to 0.94, 0.88, 0.82, 0.76, or even 0.70.

[0145] Furthermore, in the optical system 1 of this embodiment, if the value of conditional expression (22) falls below the lower limit, the image formed on the image plane by the wide-angle optical system becomes too dark.

[0146] In the optical system 1 of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (22) to 0.10. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (22) to 0.11.

[0147] In the optical system 1 of this embodiment, the optical path branching member OB is preferably a prism.

[0148] The optical system 1 of this embodiment having such a configuration can appropriately correct the field curvature, and can also increase the precision of the splitting surface BP1 of the optical path splitting member OB.

[0149] In the optical system 1 of this embodiment, it is preferable that the lens in the front lens group GF that is located closest to the object side has negative refractive power.

[0150] The optical system 1 of this embodiment having such a configuration can make the angle of view of the wide-angle end optical system sufficiently wide.

[0151] In the optical system 1 of this embodiment, the front lens group GF preferably comprises three or more lens components, where a lens component refers to a single lens or a cemented lens.

[0152] With this configuration, the optical system 1 of this embodiment can be made compact.

[0153] In the optical system 1 of this embodiment, it is preferable that at least one of the first rear lens group GR1 and the second rear lens group GR2 has a second optical path branching member having a second branching surface that reflects a portion of the incident light and transmits at least a portion different from the portion of the incident light, a third rear lens group onto which at least a portion of the light reflected by the second branching surface is incident, and a fourth rear lens group onto which at least a portion of the light transmitted by the second branching surface is incident.

[0154] The optical system 1 of this embodiment having such a configuration can form a plurality of images by the first optical system OS1 or the second optical system OS2.

[0155] In the optical system 1 of this embodiment, of the first rear lens group GR1 and the second rear lens group GR2, it is preferable that the lens group having the second optical path branching member, the third rear lens group, and the fourth rear lens group has an intermediate lens group having positive refractive power between the optical path branching member OB and the second optical path branching member.

[0156] The optical system 1 of this embodiment having such a configuration can be made compact by reducing the number of lens components that make up the rear lens group having the intermediate lens group among the first rear lens group GR1 and the second rear lens group GR2.

[0157] In the optical system 1 of this embodiment, it is preferable that the image plane of the first optical system OS1 and the image plane of the second optical system OS2 are arranged on the same plane.

[0158] In the optical system 1 of this embodiment having such a configuration, the image obtained by the first optical system OS1 and the image obtained by the second optical system OS2 can be received by a single light receiving unit arranged on the image plane, which makes it possible to reduce the size of an optical device including the optical system. Furthermore, in an optical device including an optical system having such a configuration, it is easy to synchronize the timing of capturing the two images.

[0159] In the optical system 1 in which the image plane of the first optical system OS1 and the image plane of the second optical system OS2 are arranged on the same plane, it is preferable that the overall focal length of the first optical system OS1 is longer than the overall focal length of the second optical system OS2.

[0160] The optical system 1 of this embodiment having such a configuration can shorten the distance from the lens surface closest to the object to the image plane.

[0161] In an optical system 1 in which the image plane of the first optical system OS1 and the image plane of the second optical system OS2 are arranged on the same plane, it is preferable that the first optical system OS1 further has, between the optical path branching member OB and the image plane, a first optical path changing member that changes the optical path of the light reflected at the branching surface BP1 so that it is parallel to the optical path of the light transmitted by the branching surface BP1, and a second optical path changing member that changes the optical path of the light reflected at the branching surface BP1 changed by the first optical path changing member so that the distance between it and the optical path of the light transmitted by the branching surface BP1 is shortened.

[0162] The optical system 1 of this embodiment having such a configuration can form two images close to each other, so that an optical device can be configured in which each image is received by one light receiving section.

[0163] With the above configuration, it is possible to realize an optical system that splits incident light and appropriately forms an image for each of the split light beams.

[0164] The optical device of this embodiment has the optical system configured as described above, which can split incident light and obtain image data corresponding to each light.

[0165] The optical device of this embodiment preferably has a drive unit that changes the orientation of the optical system based on image information representing the image of the optical system having the shorter overall focal length between the first optical system OS1 and the second optical system OS2.

[0166] The optical device of this embodiment has such a configuration, and can appropriately change the orientation of the optical system based on a wide range of situations represented in the image obtained by the wide-angle optical system.

[0167] In the optical device of this embodiment having a drive unit, it is preferable that the drive unit changes the orientation of the optical system so that an object detected from image information falls within the angle of view of the optical system having the longer overall focal length between the first optical system OS1 and the second optical system OS2.

[0168] By having such a configuration, the optical device of this embodiment can change the orientation of the optical system so that the image obtained by the telephoto optical system represents an object contained within a wide range represented by the image obtained by the wide-angle optical system.

[0169] The optical device of this embodiment preferably has a synthesis unit that synthesizes first image information that is an enlarged portion of the image of the optical system having the shorter overall focal length out of the first optical system OS1 and the second optical system OS2, and second image information that represents at least a portion of the image of the optical system having the longer overall focal length out of the first optical system OS1 and the second optical system OS2.

[0170] According to the optical device of this embodiment having such a configuration, it is possible to compare the portion included in the image obtained by the wide-angle side optical system with the portion included in the image obtained by the telephoto side optical system.

[0171] A manufacturing method for an optical system according to this embodiment is a manufacturing method for an optical system that has a branching surface BP1 that transmits a portion of incident light and reflects at least a portion different from the portion of the incident light, and that forms an image of a first light that is at least a portion of the light reflected by the branching surface BP1 and a second light that is at least a portion of the light transmitted by the branching surface BP1, wherein a first optical system OS1 is arranged to include, in order from the object side, a front lens group GF having negative refractive power, an optical path branching member OB that includes the branching surface BP1, and a first rear lens group GR1 onto which the first light is incident; a second optical system OS2 is arranged to include, in order from the object side, the front lens group GF, the optical path branching member OB, and a second rear lens group GR2 onto which the second light is incident; and the second optical system OS2 is configured to have an overall system focal length different from that of the first optical system OS1.

[0172] By using such a method for manufacturing an optical system, it is possible to manufacture an optical system that splits incident light and appropriately forms an image for each of the split light.

[0173] Numerical Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

[0174] In the optical system 1 of the first embodiment, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0175] FIG. 2 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the first embodiment.

[0176] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, an optical path branching member OB, an aperture stop ST1, a biconvex positive lens L11, a meniscus negative lens L12 with a convex surface facing the object side, a cemented negative lens consisting of a biconvex positive lens L13 and a biconcave negative lens L14, and a biconvex positive lens L15.

[0177] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0178] In the first optical system OS1 of this embodiment, the negative lens L1 and the negative lens L2 are included in the front lens group GF.

[0179] In the first optical system OS1 of this embodiment, the positive lens L11, the negative lens L12, the cemented negative lens of the positive lens L13 and the negative lens L14, and the positive lens L15 are included in the first rear lens group GR1.

[0180] Table 1-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0181] In the [Overall Specifications] of Table 1-1, fA is the overall focal length of the first optical system OS1, TLA is the total optical length of the first optical system OS1, FnoA is the F-number of the first optical system OS1, YmaxA is the maximum image height, ωA is the half angle of view (degrees), and Wi is the reflectance of the branching surface BP1. Note that these values ​​listed in [Overall Specifications] are values ​​for the d-line (wavelength 587.6 nm).

[0182] In the [Lens Specifications] in Table 1-1, m is the order of the optical surface counted from the object side, r is the radius of curvature, d is the surface spacing, n(d) is the refractive index for the d-line, and νd is the Abbe number for the d-line. A radius of curvature r=∞ indicates a flat surface. Additionally, in the [Lens Specifications], optical surfaces marked with an "*" are aspherical.

[0183] In Table 1-1 [Focal length data for each group],

[0184] The focal length, radius of curvature, and other lengths listed in Table 1-1 are in units of mm. However, this is not limited to this because the optical system can achieve the same optical performance even when proportionally enlarged or reduced.

[0185] The symbols in Table 1-1 described above are used in the same manner in the table for the second optical system OS2 of this embodiment and in the tables of the other embodiments described later.

[0186] (Table 1-1) [Overall specifications] fA 1.89 TLA 71.74 FnoA 2.77 YmaxA 2.31 ωA 95.0° Wi 0.20 [Lens specifications] m r d n(d) νd 1) 75.05511 2.000 1.755 52.34 2) 12.40126 9.500 3) 38.83349 1.500 1.618 63.34 4) 8.17008 5.930 5) ∞ 15.000 1.517 63.88 (Optical path branching member OB) 6) ∞ 19.600 7> ∞ 0.300 (Aperture stop ST1) 8) 17.19965 1.450 1.744 44.80 9) -36.23617 0.300 10) 5.67181 2.850 1.755 27.57 11) 3.52376 0.850 12) 6.74559 2.750 1.498 82.57 13) -4.11947 0.400 1.755 27.57 14) 10.60417 0.300 15) 10.05953 3.350 1.593 67.90 16) -5.51384 5.657 [Focal length data for each group] Group Initial surface Focal length GF 1 -7.17 GR1 8 10.92

[0187] FIG. 3 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the first embodiment.

[0188] In each aberration diagram, the spherical aberration diagram (LONGITUDINAL SPHERICAL ABERRATION) shows the ratio to the maximum aperture, the astigmatism diagram (ASTIGMATIC FIELD CURVES) and distortion diagram (DISTORTION) show values ​​for the half angle of view, and the coma diagram shows the ratio to the maximum image height. Each aberration diagram shows values ​​for the d-line and g-line (wavelength 435.8 nm). In the astigmatism diagrams, S indicates the sagittal image plane, and T indicates the meridional image plane. The same symbols as those used in the aberration diagrams of this embodiment are used in the aberration diagrams of other embodiments described below.

[0189] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0190] FIG. 4 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the first embodiment.

[0191] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, an optical path branching member OB, a biconvex positive lens L21, an aperture stop ST2, a cemented positive lens of a biconvex positive lens L22 and a meniscus negative lens L23 with a concave surface facing the object side, a cemented negative lens of a biconvex positive lens L24 and a biconcave negative lens L25, a cemented negative lens of a meniscus negative lens L26 with a convex surface facing the object side and a biconvex positive lens L27, and a meniscus positive lens L28 with a concave surface facing the object side.

[0192] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0193] In the second optical system OS2 of this embodiment, the negative lens L1 and the negative lens L2 are included in the front lens group GF, which is common to the first optical system OS1 and the same applies to the embodiments described below.

[0194] In FIG. 4, the front lens group GF is shown with a smaller aperture than the front lens group GF in FIG. 2, and this is also true in the cross-sectional views of the second optical system OS2 in each embodiment described later.

[0195] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST2, the cemented positive lens of the positive lens L22 and the negative lens L23, the cemented negative lens of the positive lens L24 and the negative lens L25, the cemented negative lens of the negative lens L26 and the positive lens L27, and the positive lens L28 are included in the second rear lens group GR2.

[0196] Table 1-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0197] In the [Overall Specifications] of Table 1-2, fB is the overall focal length of the second optical system OS2, TLB is the total optical length of the second optical system OS2, FnoB is the F-number of the second optical system OS2, YmaxB is the maximum image height, and ωB is the half angle of view (degrees). Note that these values ​​listed in [Overall Specifications] are values ​​for the d-line.

[0198] The symbols in Table 1-2 described above are also used in the tables for the second optical system OS2 in each of the examples described below.

[0199] (Table 1-2) [Overall specifications] fB 12.91 TLB 78.71 FnoB 6.32 YmaxB 2.39 ωB 10.5° [Lens specifications] m r d n(d) νd 1) 75.05511 2.000 1.755 52.340 2) 12.40126 9.500 3) 38.83349 1.500 1.618 63.340 4) 8.17008 5.930 5) ∞ 15.000 1.517 63.880 (Optical path branching member OB) 6) ∞ 0.300 7) 134.58685 2.450 1.498 82.570 8) -14.30327 0.300 9> ∞ 0.300 (Aperture stop ST2) 10) 16.40331 2.450 1.498 82.570 11) -32.55198 0.650 1.697 55.520 12) -58.63655 4.830 13) 16.96489 3.800 1.498 82.570 14) -11.72973 0.400 1.744 44.800 15) 17.71501 15.750 16) 201.11629 0.400 1.744 44.800 17) 5.19003 2.150 1.487 70.320 18) -31.23476 6.500 19) -242.08751 1.450 1.620 36.400 20) -13.28229 3.049 [Focal length data for each group] Group Initial surface Focal length GF 1 -7.17 GR2 7 57.12

[0200] FIG. 5 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the first embodiment.

[0201] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0202] Second Example In the optical system 1 of the second example, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0203] FIG. 6 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the second embodiment.

[0204] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, a biconcave negative lens L3, an optical path branching member OB, an aperture stop ST1, a biconvex positive lens L11, a meniscus negative lens L12 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L13 and a biconcave negative lens L14, and a biconvex positive lens L15.

[0205] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0206] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0207] In the first optical system OS1 of this embodiment, the positive lens L11, the negative lens L12, the cemented positive lens of the positive lens L13 and the negative lens L14, and the positive lens L15 are included in the first rear lens group GR1.

[0208] Table 2-1 below lists the specifications of the first optical system OS1 of this embodiment.

[0209] In the [Aspherical Data] of Table 2-1, m indicates the optical surface corresponding to the aspherical data, K indicates the conic constant, and A4 to A10 indicate the aspherical coefficients.

[0210] The aspherical 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 aspherical surface at height y to each aspherical 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 n-th order aspherical coefficient. In each example, the second order aspherical coefficient A2 is 0. Also, "En" is expressed as "×10 －ｎ " indicates.

[0211] (a) 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

[0212] The symbols in Table 2-1 described above are used in the same manner in the table for the second optical system OS2 of this embodiment and in the tables of the other embodiments described later.

[0213] (Table 2-1) [Overall specifications] fA 1.48 TLA 72.20 FnoA 2.77 YmaxA 2.40 ωA 97.0° Wi 0.20 [Lens specifications] m r d n(d) νd 1) 42.23761 2.000 1.773 49.62 2) 18.35239 12.350 * 3) 213.21931 1.500 1.694 53.20 * 4) 10.55620 6.400 5) -18.79738 0.400 1.593 67.90 6) 13.14408 1.350 7) ∞ 15.000 1.517 63.88 (Optical path splitter OB) 8) ∞ 12.250 9> ∞ 0.100 (Aperture stop ST1) 10) 33.48408 1.000 1.744 44.80 11) -103.76024 0.300 12) 7.49600 5.100 1.755 27.57 13) 4.43565 0.300 14) 3.99229 5.250 1.519 69.89 15) -3.14423 0.400 1.755 27.57 16) 9.94355 0.300 *17) 4.05633 5.900 1.694 53.20 *18) -25.33643 2.300 [Aspherical data] m K A4 A6 A8 A10 3) 5.7420 2.20E-04 -1.62E-06 4.03E-09 2.36E-19 4) 0.3929 3.75E-04 6.37E-07 3.65E-16 3.68E-19 17) -0.3515 -7.02E-04 2.51E-05 -1.55E-06 -3.91E-08 18) -2.8412 3.85E-03 9.41E-04 -1.14E-04 1.77E-05 [Focal length data for each group] Group Initial surface Focal length GF 1 -3.95 GR1 10 10.21

[0214] FIG. 7 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the second example.

[0215] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0216] FIG. 8 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the second embodiment.

[0217] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, a biconcave negative lens L3, an optical path branching member OB, a biconvex positive lens L21, an aperture stop ST2, a meniscus negative lens L22 with a convex surface facing the object side, a cemented positive lens of a biconvex positive lens L23 and a meniscus negative lens L24 with a concave surface facing the object side, a cemented negative lens of a biconcave negative lens L25 and a biconvex positive lens L26, and a cemented positive lens of a meniscus negative lens L27 with a convex surface facing the object side and a biconvex positive lens L28.

[0218] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0219] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0220] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST2, the negative lens L22, the cemented positive lens of the positive lens L23 and the negative lens L24, the cemented negative lens of the negative lens L25 and the positive lens L26, and the cemented positive lens of the negative lens L27 and the positive lens L28 are included in the second rear lens group GR2.

[0221] Table 2-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0222] (Table 2-2) [Overall specifications] fB 12.85 TLB 112.18 FnoB 6.32 YmaxB 2.28 ωB 10.0° [Lens specifications] m r d n(d) νd 1) 42.23761 2.000 1.773 49.62 2) 18.35239 12.350 * 3) 213.21931 1.500 1.694 53.20 * 4) 10.55620 6.400 5) -18.79738 0.400 1.593 67.90 6) 13.14408 1.350 7) ∞ 15.000 1.517 63.88 (Optical path splitter OB) 8) ∞ 0.300 9) 33.83714 2.170 1.603 60.69 10) -15.49196 3.700 11) ∞ 0.000 (Aperture stop ST2) 12) 15.63559 0.600 1.744 44.80 13) 9.50756 0.300 14) 9.04713 3.300 1.498 82.57 15) -10.90940 0.400 1.744 44.80 16) -35.61306 11.400 17) -19.84006 0.400 1.744 44.80 18) 8.37976 1.120 1.620 36.40 19) -33.60000 41.450 20) 11.10000 0.420 1.755 27.57 21) 5.35000 1.700 1.498 82.57 22) -21.60000 5.919 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 2.20E-04 -1.62E-06 4.03E-09 2.36E-19 4) 0.3929 3.75E-04 6.37E-07 3.65E-16 3.68E-19 [Focal length data for each group] Group First surface Focal length GF 1 -3.95 GR2 9 -12.32

[0223] FIG. 9 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the second embodiment.

[0224] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0225] In the optical system 1 of the third embodiment, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0226] FIG. 10 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the third embodiment.

[0227] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with its convex surface facing the object side, a biconcave negative lens L2, an optical path branching member OB, an aperture stop ST1, a meniscus positive lens L11 with its concave surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L12 and a biconcave negative lens L13, and a meniscus positive lens L14 with its convex surface facing the object side.

[0228] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0229] In the first optical system OS1 of this embodiment, the negative lens L1 and the negative lens L2 are included in the front lens group GF.

[0230] In the first optical system OS2 of this embodiment, the positive lens L11, the negative lens L12, the cemented positive lens of the positive lens L13 and the negative lens L14, and the positive lens L15 are included in the first rear lens group GR1.

[0231] Table 3-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0232] (Table 3-1) [Overall specifications] fA 2.06 TLA 44.69 FnoA 2.00 YmaxA 2.45 ωA 78.0° Wi 0.10 [Lens specifications] m r d n(d) νd 1) 23.88511 2.000 1.755 52.34 2) 9.94429 6.700 3) -83.42533 1.500 1.618 63.34 4) 4.78676 5.280 5) ∞ 10.000 1.517 63.88 (Optical path branching member OB) 6) ∞ 1.500 7> ∞ 0.100 (Aperture stop ST1) 8) -242.51150 3.130 1.744 44.80 9) -13.46579 1.890 10) 4.81511 6.000 1.519 69.89 11) -4.20835 0.400 1.755 27.57 12) 6.09372 0.300 *13) 3.54046 2.340 1.583 59.46 *14) -80.74067 3.553 [Aspheric data] m K A4 A6 A8 A10 13) -0.5664 -5.22E-04 3.18E-05 1.03E-05 -6.79E-07 14) 6.1480 3.31E-03 1.12E-05 4.52E-05 -3.75E-06 [Focal length data for each group] Group First surface Focal length GF 1 -4.60 GR1 8 7.17

[0233] FIG. 11 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the third example.

[0234] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0235] FIG. 12 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the third embodiment.

[0236] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, an optical path branching member OB, a meniscus positive lens L21 with a concave surface facing the object side, an aperture stop ST2, a meniscus negative lens L22 with a convex surface facing the object side, a cemented positive lens of a biconvex positive lens L23 and a meniscus negative lens L24 with a concave surface facing the object side, a cemented negative lens of a biconcave negative lens L25 and a biconvex positive lens L26, and a cemented positive lens of a meniscus negative lens L27 with a convex surface facing the object side and a biconvex positive lens L28.

[0237] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0238] In the second optical system OS2 of this embodiment, the negative lens L1 and the negative lens L2 are included in the front lens group GF.

[0239] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST2, the negative lens L22, the cemented positive lens of the positive lens L23 and the negative lens L24, the cemented negative lens of the negative lens L25 and the positive lens L26, and the cemented positive lens of the negative lens L27 and the positive lens L28 are included in the second rear lens group GR2.

[0240] Table 3-2 below lists the values ​​of the specifications of the second optical system OS2 of this embodiment.

[0241] (Table 3-2) [Overall specifications] fB 12.90 TLB 84.32 FnoB 6.57 YmaxB 2.28 ωB 10.0° [Lens specifications] m r d n(d) νd 1) 23.88511 2.000 1.755 52.34 2) 9.94429 6.700 3) -83.42533 1.500 1.618 63.34 4) 4.78676 5.280 5) ∞ 10.000 1.517 63.88 (Optical path branching member OB) 6) ∞ 0.300 7) -6118.32762 2.000 1.603 60.69 8) -9.74192 1.850 9> ∞ 0.110 (Aperture stop ST2) 10) 15.72367 0.400 1.744 44.80 11) 8.88523 0.300 12) 7.99714 3.000 1.498 82.57 13) -8.68959 0.120 1.744 44.80 14) -25.95611 8.600 15) -18.47079 0.400 1.744 44.80 16) 7.52706 1.180 1.620 36.40 17) -33.60000 33.800 18) 11.10000 0.400 1.755 27.57 19) 5.35000 1.570 1.498 82.57 20) -21.60000 4.805 [Focal length data for each group] Group Initial surface Focal length GF 1 -4.60 GR2 7 -21.79

[0242] FIG. 13 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the third embodiment.

[0243] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0244] In the optical system 1 of the fourth embodiment, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0245] FIG. 14 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the fourth embodiment.

[0246] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a concave surface facing the object side, an optical path branching member OB, a meniscus positive lens L11 with a convex surface facing the object side, an aperture stop ST1, a meniscus negative lens L12 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L13 and a biconcave negative lens L14, a meniscus negative lens L15 with a convex surface facing the object side, and a meniscus positive lens L16 with a convex surface facing the object side.

[0247] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0248] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0249] In the first optical system OS2 of this embodiment, the positive lens L11, the aperture stop ST1, the negative lens L12, the cemented positive lens of the positive lens L13 and the negative lens L14, the negative lens L15, and the positive lens L16 are included in the first rear lens group GR1.

[0250] Table 4-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0251] (Table 4-1) [Overall specifications] fA 2.16 TLA 101.18 FnoA 2.78 YmaxA 2.28 ωA 91.0° Wi 0.20 [Lens specifications] m r d n(d) νd 1) 113.14209 1.500 1.744 44.80 2) 15.03926 10.100 3) -36.13818 1.000 1.487 70.32 4) 13.38947 5.000 5) -77.29143 2.000 1.755 27.57 6) -31.72172 0.100 7) ∞ 20.000 1.517 63.88 (Optical path splitter OB) 8) ∞ 37.400 9) 13.50027 2.650 1.750 35.25 10) 54.25029 4.610 11) ∞ 0.160 (Aperture stop ST1) 12) 9.05782 0.550 1.755 27.57 13) 5.17965 0.110 14) 5.22254 4.500 1.519 69.89 15) -11.42347 0.300 1.755 27.57 16) 32.62581 0.100 17) 8.22833 7.550 1.620 60.24 18) 6.68071 0.410 19) 7.50400 1.540 1.620 60.24 20) 37.41418 1.598 [Focal length data for each group] Group Initial surface Focal length GF 1 -12.06 GR1 9 12.20

[0252] FIG. 15 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the fourth example.

[0253] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0254] FIG. 16 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the fourth example.

[0255] The second optical system OS2 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a concave surface facing the object side, an optical path branching member OB, a biconvex positive lens L21, an aperture stop ST2, a meniscus negative lens L22 with a convex surface facing the object side, a cemented negative lens consisting of a biconvex positive lens L23 and a biconcave negative lens L24, a biconvex positive lens L25, a meniscus negative lens L26 with a convex surface facing the object side, and a meniscus positive lens L27 with a concave surface facing the object side.

[0256] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0257] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0258] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST2, the negative lens L22, the cemented negative lens of the positive lens L23 and the negative lens L24, the positive lens L25, the negative lens L26, and the positive lens L27 are included in the second rear lens group GR2.

[0259] Table 4-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0260] (Table 4-2) [Overall specifications] fB 13.07 TLB 100.39 FnoB 5.25 YmaxB 2.28 ωB 10.0° [Lens specifications] m r d n(d) νd 1) 113.14209 1.500 1.744 44.80 2) 15.03926 10.100 3) -36.13818 1.000 1.487 70.32 4) 13.38947 5.000 5) -77.29143 2.000 1.755 27.57 6) -31.72172 0.100 7) ∞ 20.000 1.517 63.88 8) ∞ 0.100 9) 20.67358 1.660 1.699 30.13 10) -69.69443 4.450 11) ∞ 2.050 12) 18.45580 3.940 1.750 35.25 13) 8.14654 0.100 14) 6.40148 5.450 1.487 70.32 15) -9.26710 0.350 1.850 32.35 16) 6.70776 0.170 17) 7.36263 2.050 1.589 61.22 18) -18.62826 17.900 19) 13.55205 5.500 1.755 27.57 20) 10.51263 2.000 21) -204.26697 4.320 1.755 27.57 22) -16.00927 10.651 [Focal length data for each group] Group Initial surface Focal length GF 1 -12.06 GR2 9 53.94

[0261] FIG. 17 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the fourth embodiment.

[0262] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0263] In the optical system 1 of the fifth embodiment, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0264] FIG. 18 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the fifth embodiment.

[0265] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with its convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with its convex surface facing the object side, an optical path branching member OB, a biconvex positive lens L11, an aperture stop ST1, a cemented negative lens consisting of a biconvex positive lens L12 and a biconcave negative lens L13, a biconvex positive lens L14, and a meniscus positive lens L15 with its convex surface facing the object side.

[0266] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0267] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0268] In the first optical system OS2 of this embodiment, the positive lens L11, the aperture stop ST1, the cemented negative lens of the positive lens L12 and the negative lens L13, the positive lens L14, and the positive lens L15 are included in the first rear lens group GR1.

[0269] Table 5-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0270] (Table 5-1) [Overall specifications] fA 1.91 TLA 50.00 FnoA 1.90 YmaxA 2.29 ωA 91.0° Wi 0.10 [Lens specifications] m r d n(d) νd 1) 52.94033 1.500 1.720 50.27 2) 10.22772 6.940 * 3) -86.42248 1.000 1.553 71.68 * 4) 7.86002 3.110 5) 10.21092 2.000 1.847 23.80 6) 10.22927 1.916 7) ∞ 12.000 1.517 63.88 (Optical path splitter OB) 8) ∞ 3.600 9) 13.72573 2.250 1.755 27.57 10) -1445.37868 1.970 11> ∞ 1.550 (Aperture stop ST1) 12) 6.35540 3.000 1.519 69.89 13) -8.00624 0.400 1.847 23.80 14) 10.34236 0.300 15) 6.40110 2.050 1.640 60.19 16) -1099.36165 1.500 *17) 4.48330 2.860 1.801 45.45 *18) 4.93022 2.052 [Aspherical data] m K A4 A6 A8 A10 3) -9.3823 7.30E-06 5.43E-11 6.84E-24 0.00E+00 4) 0.4220 6.82E-06 -1.39E-11 2.07E-28 0.00E+00 17) -0.2893 -4.86E-05 -5.84E-05 4.78E-06 -7.43E-07 18) -2.5897 7.06E-03 -2.43E-04 6.71E-05 -1.12E-05 [Focal length data for each group] Group Initial surface Focal length GF 1 -6.07 GR1 9 7.14

[0271] FIG. 19 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the fifth example.

[0272] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0273] FIG. 20 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the fifth embodiment.

[0274] The second optical system OS2 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a convex surface facing the object side, an optical path branching member OB, a biconvex positive lens L21, an aperture stop ST2, a meniscus negative lens L22 with a convex surface facing the object side, a cemented negative lens consisting of a biconvex positive lens L23 and a biconcave negative lens L24, a biconvex positive lens L25, a meniscus negative lens L26 with a convex surface facing the object side, and a biconvex positive lens L27.

[0275] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0276] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0277] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST2, the negative lens L22, the cemented negative lens of the positive lens L23 and the negative lens L24, the positive lens L25, the negative lens L26, and the positive lens L27 are included in the second rear lens group GR2.

[0278] Table 5-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0279] (Table 5-2) [Overall specifications] fB 12.91 TLB 79.52 FnoB 6.25 YmaxB 2.28 ωB 10.0° [Lens specifications] m r d n(d) νd 1) 52.94033 1.500 1.720 50.27 2) 10.22772 6.940 * 3) -86.42248 1.000 1.553 71.68 * 4) 7.86002 3.110 5) 10.21092 2.000 1.847 23.80 6) 10.22927 1.916 7) ∞ 12.000 1.517 63.88 (Optical path splitter OB) 8) ∞ 0.100 9) 30.93140 1.310 1.699 30.13 10) -18.03001 0.300 11) ∞ 0.400 (Aperture stop ST2) 12) 12.63426 3.940 1.750 35.25 13) 6.79988 0.100 14) 6.13728 5.450 1.487 70.32 15) -8.01512 0.350 1.850 32.35 16) 7.58006 0.260 17) 8.09915 1.660 1.487 70.32 18) -9.37886 17.900 19) 74.85170 5.500 1.755 27.57 20) 7.26414 2.000 21) 42.09757 4.320 1.755 27.57 22) -9.31976 7.460 [Aspheric surface data] m K A4 A6 A8 A10 3) -9.3823 7.30E-06 5.43E-11 6.84E-24 0.00E+00 4) 0.4220 6.82E-06 -1.39E-11 2.07E-28 0.00E+00 [Focal length data for each group] Group Initial surface Focal length GF 1 -6.07 GR2 9 -300.89

[0280] FIG. 21 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the fifth embodiment.

[0281] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0282] Sixth Example In the optical system 1 of the sixth example, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0283] FIG. 22 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the sixth example.

[0284] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a concave surface facing the object side, an optical path branching member OB, a biconvex positive lens L11, an aperture stop ST1, a meniscus negative lens L12 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L13 and a biconcave negative lens L14, a biconvex positive lens L15, and a meniscus negative lens L16 with a convex surface facing the object side.

[0285] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0286] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0287] In the first optical system OS1 of this embodiment, the positive lens L11, the aperture stop ST1, the positive lens L12, the cemented positive lens of the positive lens L13 and the negative lens L14, the positive lens L15, and the negative lens L16 are included in the first rear lens group GR1.

[0288] Table 6-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0289] (Table 6-1) [Overall specifications] fA 1.92 TLA 69.94 FnoA 2.31 YmaxA 2.28 ωA 90.5° Wi 0.30 [Lens specifications] m r d n(d) νd 1) 55.24628 2.009 1.755 27.57 2) 9.61973 10.260 3) -17.84622 1.500 1.618 63.34 4) 11.21493 6.270 5) -71.15753 1.800 1.755 27.57 6) -22.22626 1.080 7) ∞ 13.000 1.517 63.88 8) ∞ 9.420 9) 18.37359 2.070 1.750 35.25 10) -522.06366 4.950 11) ∞ 2.370 12) 8.49437 1.420 1.755 27.57 13) 5.23094 1.650 14) 5.83639 2.570 1.519 69.89 15) -8.16757 0.350 1.755 27.57 16) 17.26271 0.100 17) 5.85248 2.740 1.620 60.24 18) -26.28387 1.370 *19) 6.96368 0.350 1.589 61.25 *20) 6.13135 4.665 [Aspherical data] m K A4 A6 A8 A10 19) -9.3396 1.38E-03 -6.73E-04 1.64E-05 -9.36E-07 20) -0.2775 7.44E-06 -3.66E-04 6.94E-06 2.95E-07 [Focal length data for each group] Group Initial surface Focal length GF 1 -7.39 GR1 9 11.73

[0290] FIG. 23 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the sixth example.

[0291] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0292] FIG. 24 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the sixth example.

[0293] The second optical system OS2 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a concave surface facing the object side, an optical path branching member OB, a biconvex positive lens L21, an aperture stop ST2, a meniscus negative lens L22 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L23 and a biconcave negative lens L24, a biconvex positive lens L25, and a meniscus negative lens L26 with a concave surface facing the object side.

[0294] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0295] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0296] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST2, the negative lens L22, the cemented positive lens of the positive lens L23 and the negative lens L24, the positive lens L25, and the negative lens L26 are included in the second rear lens group GR2.

[0297] Table 6-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0298] (Table 6-2) [Overall specifications] fB 6.59 TLB 75.00 FnoB 4.15 YmaxB 2.28 ωB 20.0° [Lens specifications] m r d n(d) νd 1) 55.24628 2.009 1.755 27.57 2) 9.61973 10.260 3) -17.84622 1.500 1.618 63.34 4) 11.21493 6.270 5) -71.15753 1.800 1.755 27.57 6) -22.22626 1.080 7) ∞ 13.000 1.517 63.88 (Optical path branching member OB) 8) ∞ 0.830 9) 14.43212 2.650 1.658 50.83 10) -66.29208 4.560 11> ∞ 0.100 (Aperture stop ST2) 12) 20.00592 5.500 1.744 44.80 13) 5.22811 0.100 14) 4.64067 3.780 1.487 70.32 15) -4.78843 0.350 1.750 35.25 16) 24.84195 0.100 17) 6.34924 3.540 1.487 70.32 18) -53.28985 1.400 *19) -26.24408 3.200 1.553 71.68 *20) -31.44606 12.970 [Aspherical data] m K A4 A6 A8 A10 19) 9.4243 -1.46E-03 -5.94E-05 3.96E-06 -5.04E-07 20) -10.0000 -7.02E-04 4.07E-06 5.37E-08 -3.82E-10 [Focal length data for each group] Group First surface Focal length GF 1 -7.39 GR2 9 16.75

[0299] FIG. 25 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the sixth embodiment.

[0300] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0301] Seventh Example FIG. 26 is a schematic diagram illustrating the overall configuration of an optical system 1 of a seventh example.

[0302] In the optical system 1 of this embodiment, the first optical system OS1 has an overall focal length that is longer than the overall focal length of the second optical system OS2. That is, the first optical system OS1 corresponds to a telephoto-side optical system, and the second optical system OS2 corresponds to a wide-angle-side optical system.

[0303] In this embodiment, the image plane I1 of the first optical system OS1 and the image plane I2 of the second optical system OS2 are arranged on the same plane.

[0304] The first optical system OS1 in this embodiment has a first optical path changing member between the optical path branching member OB and the image plane I1, which changes the optical path of light reflected by the branching surface BP1 so that it is parallel to the optical path of light transmitted by the branching surface BP1.

[0305] In this embodiment, the first optical path changing member is configured as a right-angle prism RAP1 having a reflecting surface that changes the incident light so that it becomes parallel to the optical path of the light transmitted by the splitting surface BP1. The first optical path changing member may also be configured as a mirror having a reflecting surface that changes the incident light so that it becomes parallel to the optical path of the light transmitted by the splitting surface BP1.

[0306] The first optical system OS1 of this embodiment has a second optical path changing member between the first optical path changing member and the image plane, which changes the optical path of the light reflected by the branching surface BP1 changed by the first optical path changing member so that the distance between the optical path of the light transmitted by the branching surface BP1 is shortened.

[0307] In this embodiment, the second optical path changing member is composed of a right-angle prism RAP2 having a reflecting surface that emits incident light in a direction approaching the optical path of the light transmitted by the splitting surface BP1, and a right-angle prism RAP3 that changes the incident light to be parallel to the optical path of the light transmitted by the splitting surface BP1 and emits the light toward the image plane I1. At least one of the right-angle prisms RAP2 and RAP3 may be composed of a mirror.

[0308] FIG. 27 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the seventh example.

[0309] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a concave surface facing the object side, an optical path branching member OB, a right-angle prism RAP1, a biconvex positive lens L11, an aperture stop ST1, a meniscus negative lens L12 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L13 and a biconcave negative lens L14, a biconvex positive lens L15, a meniscus negative lens L16 with a concave surface facing the object side, a right-angle prism RAP2, and a right-angle prism RAP3.

[0310] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0311] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0312] In the first optical system OS1 of this embodiment, the positive lens L11, the aperture stop ST1, the negative lens L12, the cemented positive lens of the positive lens L13 and the negative lens L14, the positive lens L15, and the negative lens L16 are included in the first rear lens group GR1.

[0313] Table 7-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0314] (Table 7-1) [Overall specifications] fB 6.55 TLB 83.09 FnoB 6.34 YmaxB 2.28 ωB 20.0° [Lens specifications] m r d n(d) νd 1) 55.24628 2.000 1.755 27.57 2) 9.61973 10.250 3) -17.84622 1.500 1.618 63.34 4) 11.21493 7.200 5) -71.15753 1.150 1.755 27.57 6) -22.22626 1.080 7) ∞ 13.000 1.517 63.88 (Optical path branching member OB) 8) ∞ 10.000 1.517 63.88 (Right-angle prism RAP1) 9) ∞ 0.100 10) 13.67209 1.250 1.487 70.32 11) -36.76898 9.620 12> ∞ 0.100 (Aperture stop ST1) 13) 7.88779 1.980 1.700 48.10 14) 3.58263 0.100 15) 2.98620 3.700 1.487 70.32 16) -2.83913 3.690 1.744 44.80 17) 4.49639 0.100 18) 2.48008 1.410 1.517 52.20 19) -3.50305 0.100 *20) -3.69419 3.410 1.801 45.45 *21) -101.19485 11.353 [Aspherical data] m K A4 A6 A8 A10 20) 1.4129 -1.82E-03 -6.13E-04 1.07E-04 1.97E-05 21) -10.0000 1.59E-03 -1.76E-04 3.12E-04 -3.67E-05 [Focal length data for each group] Group Initial surface Focal length GF 1 -7.48 GR1 10 15.40

[0315] FIG. 28 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the seventh embodiment.

[0316] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0317] FIG. 29 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the seventh example.

[0318] The second optical system OS2 of this embodiment has, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a meniscus positive lens L3 with a concave surface facing the object side, an optical path branching member OB, a meniscus positive lens L21 with a convex surface facing the object side, an aperture stop ST2, a meniscus negative lens L22 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L23 and a biconcave negative lens L24, a biconvex positive lens L25, and a meniscus negative lens L26 with a convex surface facing the object side.

[0319] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0320] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0321] In the second optical system OS2 of this embodiment, the positive lens L21, the aperture stop ST1, the negative lens L22, the cemented positive lens of the positive lens L23 and the negative lens L24, the positive lens L25, and the negative lens L26 are included in the second rear lens group GR2.

[0322] Table 7-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0323] (Table 7-2) [Overall specifications] fA 1.92 TLA 70.00 FnoA 2.50 YmaxA 2.28 ωA 90.0° Wi 0.10 [Lens specifications] m r d n(d) νd 1) 55.24628 2.000 1.755 27.57 2) 9.61973 10.250 3) -17.84622 1.500 1.618 63.34 4) 11.21493 7.200 5) -71.15753 1.150 1.755 27.57 6) -22.22626 1.080 7) ∞ 13.000 1.517 63.88 (Optical path splitter OB) 8) ∞ 12.400 9) 11.78881 2.150 1.717 29.57 10) 64.32439 4.930 11> ∞ 0.100 (Aperture stop ST2) 12) 10.16492 1.370 1.755 27.57 13) 4.67717 0.125 14) 5.03005 2.200 1.519 69.89 15) -6.87158 0.350 1.755 27.57 16) 27.60947 0.100 17) 5.84371 4.590 1.620 60.24 18) -28.71086 0.400 *19) 5.57062 0.350 1.620 60.24 *20) 4.72991 4.755 [Aspherical data] m K A4 A6 A8 A10 19) -0.5510 -7.61E-04 -1.43E-04 1.23E-05 -3.04E-07 20) -0.1419 -1.46E-04 -1.09E-04 1.55E-05 7.86E-07 [Focal length data for each group] Group First surface Focal length GF 1 -7.48 GR2 9 10.99

[0324] FIG. 30 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the seventh example.

[0325] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0326] Eighth Example FIG. 31 is a schematic diagram illustrating the overall configuration of an optical system according to an eighth example.

[0327] In this embodiment, light incident on the front lens group GF is split into reflected light and transmitted light by the splitting surface BP1 of the optical path splitting member OB.

[0328] The light reflected by the splitting surface BP1 enters an optical path splitting member OBx having a splitting surface BPx that transmits a portion of the incident light and reflects at least a portion different from the portion of the incident light, and is further split by the splitting surface BPx into reflected light and transmitted light. The optical path splitting member OBx is a cube-type beam splitter (prism) having the splitting surface BPx. The optical path splitting member OBx may also be a flat-plate beam splitter (half mirror) having the splitting surface BPx.

[0329] The light (optical axis AXa) transmitted by the splitting surface BPx is incident on the lens group Ga and forms an image on the image plane Ia. The light (optical axis AXb) reflected by the splitting surface BPx is incident on the lens group Gb and forms an image on the image plane Ib.

[0330] The light transmitted by the splitting surface BP1 passes through the intermediate lens group GM and enters an optical path splitting member OBy having a splitting surface BPy that transmits a portion of the incident light and reflects at least a portion different from the portion of the incident light, and is further split by the splitting surface BPy into reflected light and transmitted light. The optical path splitting member OBy is a cube-type beam splitter (prism) having the splitting surface BPy. The optical path splitting member OBy may also be a flat-plate beam splitter (half mirror) having the splitting surface BPy.

[0331] The light (optical axis AXc) reflected by the splitting surface BPy is incident on the lens group Gc and forms an image on the image plane Ic, while the light (optical axis AXd) transmitted through the splitting surface BPy is incident on the lens group Gd and forms an image on the image plane Id.

[0332] In the optical system of Example 8, the first rear lens group GR1, onto which first light (optical axis AXa, AXb), which is at least a portion of the light reflected by the splitting surface BP, is incident, includes an optical path splitting member OBx, a lens group Ga, and a lens group Gb. The optical path splitting member OBx is an example of a second optical path splitting member having a second splitting surface that reflects a portion of the incident light and transmits at least a portion different from the portion of the incident light. The lens group Gb is an example of a third rear lens group onto which at least a portion (optical axis AXb) of the light reflected by the second splitting surface is incident. The lens group Ga is an example of a fourth rear lens group onto which at least a portion (optical axis AXa) of the light transmitted by the second splitting surface is incident.

[0333] In the optical system of Example 8, the second rear lens group GR2, onto which second light (optical axis AXc, AXd), which is at least a portion of the light transmitted by the splitting surface BP, is incident, includes an intermediate lens group GM, an optical path splitting member OBy, a lens group Gc, and a lens group Gd. The optical path splitting member OBy is another example of a second optical path splitting member having a second splitting surface that reflects a portion of the incident light and transmits at least a portion different from the portion of the incident light. The lens group Gc is another example of a third rear lens group onto which at least a portion of the light reflected by the second splitting surface (optical axis AXc) is incident. The lens group Gd is another example of a fourth rear lens group onto which at least a portion of the light transmitted by the second splitting surface (optical axis AXd) is incident.

[0334] An optical system having an optical system OSa including a front lens group GF, an optical path branching member OB, an optical path branching member OBx, and a lens group Ga as a first optical system OS1, and an optical system OSd including a front lens group GF, an optical path branching member OB, an intermediate lens group GM, an optical path branching member OBy, and a lens group Gd as a second optical system OS2 is referred to as the optical system of Example 8-1. In the optical system of Example 8-1, the lens group Ga corresponds to the first rear lens group GR1, and the intermediate lens group GM, the optical path branching member OBy, and the lens group Gd correspond to the second rear lens group GR2. In the optical system of Example 8-1, the second optical system OS2 has an overall system focal length longer than the overall system focal length of the first optical system OS1. In other words, the first optical system OS1 corresponds to a wide-angle side optical system, and the second optical system OS2 corresponds to a telephoto side optical system.

[0335] An optical system having an optical system OSb including a front lens group GF, an optical path branching member OB, an optical path branching member OBx, and a lens group Gb as a first optical system OS1, and an optical system OSc including a front lens group GF, an optical path branching member OB, an intermediate lens group GM, an optical path branching member OBy, and a lens group Gc as a second optical system OS2 is referred to as the optical system of Example 8-2. In the optical system of Example 8-2, the lens group Gb corresponds to the first rear lens group GR1, and the intermediate lens group GM, the optical path branching member OBy, and the lens group Gc correspond to the second rear lens group GR2. In the optical system of Example 8-2, the second optical system OS2 has an overall system focal length longer than the overall system focal length of the first optical system OS1. In other words, the first optical system OS1 corresponds to a wide-angle side optical system, and the second optical system OS2 corresponds to a telephoto side optical system.

[0336] Example 8-1 FIG. 32 is a cross-sectional view of a first optical system OS1 included in an optical system of Example 8-1.

[0337] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with its convex surface facing the object side, a biconcave negative lens L2, a biconcave negative lens L3, an optical path branching member OB, an optical path branching member OBx, an aperture stop STa, a biconvex positive lens La1, a meniscus negative lens La2 with its convex surface facing the object side, a cemented positive lens formed by a biconvex positive lens La3 and a biconcave negative lens La4, and a biconvex positive lens La5.

[0338] A first image pickup element (not shown) made up of a CCD, CMOS, or the like is disposed on the image plane Ia.

[0339] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0340] In the first optical system OS1 of this embodiment, the positive lens La1, the negative lens La2, the cemented positive lens of the positive lens La3 and the negative lens La4, and the positive lens La5 are included in the first rear lens group GR1.

[0341] Table 8-1-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0342] (Table 8-1-1) [Overall specifications] fA 1.49 TLA 72.51 FnoA 2.55 YmaxA 2.29 ωA 91.0° Wi 0.20 [Lens specifications] m r d n(d) νd 1) 39.16597 2.000 1.773 49.62 2) 18.66022 11.700 * 3) -38.70105 1.500 1.694 53.20 * 4) 13.43728 6.400 5) -32.89788 0.400 1.593 67.90 6) 14.35387 1.350 7) ∞ 13.000 1.569 56.00 (Optical path branching member OB) 8) ∞ 0.000 9) ∞ 13.000 1.569 56.00 (Optical path branching member OBx) 10) ∞ 5.772 11) ∞ 0.100 (Aperture stop ST1) 12) 44.44798 0.720 1.744 44.80 13) -32.08087 0.300 14) 6.77592 3.730 1.755 27.57 15) 4.60673 0.600 16) 3.92339 4.350 1.519 69.89 17) -3.61688 0.400 1.755 27.57 18) 5.04451 0.300 *19) 3.69377 4.290 1.694 53.20 *20) -22.98903 2.600 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 3.95E-04 -2.07E-06 2.93E-09 5.51E-12 4) 0.2784 6.62E-04 -4.55E-06 3.07E-07 -1.97E-09 19) -0.2736 -9.10E-04 7.22E-06 -4.67E-06 2.19E-07 20) 4.5259 3.65E-03 6.68E-04 -7.89E-05 1.06E-05 [Focal length data for each group] Group First surface Focal length GF 1 -4.45 GR1 12 9.01

[0343] FIG. 33 is a diagram showing various aberrations of the first optical system OS1 of the optical system of Example 8-1.

[0344] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0345] FIG. 34 is a cross-sectional view of the second optical system OS2 included in the optical system of Example 8-1.

[0346] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a biconcave negative lens L3, an optical path branching member OB, an aperture stop STM, a biconvex positive lens LM1, a meniscus negative lens LM2 with a convex surface facing the object side, a cemented positive lens of the biconvex positive lens LM3 and a meniscus negative lens LM4 with a concave surface facing the object side, an optical path branching member OBy, a cemented negative lens of the meniscus negative lens Ld1 with a convex surface facing the object side and a meniscus positive lens Ld2 with a convex surface facing the object side, and a cemented positive lens of the meniscus negative lens Ld3 with a convex surface facing the object side and a biconvex positive lens Ld4.

[0347] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane Id.

[0348] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0349] In the second optical system OS2 of this embodiment, the positive lens LM1, the negative lens LM2, the cemented positive lens of the positive lens LM3 and the negative lens LM4, the optical path branching member OBy, the cemented negative lens of the negative lens Ld1 and the positive lens Ld2, and the cemented positive lens of the negative lens Ld3 and the positive lens Ld4 are included in the second rear lens group GR2.

[0350] Table 8-1-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0351] (Table 8-1-2) [Overall specifications] fB 12.98 TLB 119.03 FnoB 6.24 YmaxB 2.26 ωB 10.0° [Lens specifications] m r d n(d) νd 1) 39.16597 2.000 1.773 49.62 2) 18.66022 11.700 3) -38.70105 1.500 1.694 53.20 4) 13.43728 6.400 5) -32.89788 0.400 1.593 67.90 6) 14.35387 1.350 7) ∞ 13.000 1.569 56.00 (Optical path splitter OB) 8) ∞ 2.000 9> ∞ 0.000 (Aperture stop STM) 10) 41.72564 5.000 1.603 60.69 11) -19.13995 0.120 12) 28.95936 1.000 1.744 44.80 13) 12.91167 0.300 14) 13.46515 5.000 1.498 82.57 15) -18.53975 0.350 1.744 44.80 16) -29.76038 8.990 17) ∞ 13.000 1.569 56.00 (Optical path splitter OBy) 18) ∞ 7.665 19) 20.30377 0.666 1.700 48.10 20) 8.14493 4.634 1.518 58.82 21) 21.41908 28.790 22) 12.24203 0.350 1.755 27.57 23) 4.03397 3.110 1.498 82.57 24) -8.72384 1.708 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 3.95E-04 -2.07E-06 2.93E-09 5.51E-12 4) 0.2784 6.62E-04 -4.55E-06 3.07E-07 -1.97E-09 [Focal length data for each group] Group First surface Focal length GF 1 -4.45 GR2 10 -10.02 .

[0352] FIG. 35 is a diagram showing various aberrations of the second optical system OS2 of the optical system of Example 8-1.

[0353] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0354] Example 8-2 FIG. 36 is a cross-sectional view of a first optical system OS1 included in an optical system of Example 8-2.

[0355] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus negative lens L1 with its convex surface facing the object side, a biconcave negative lens L2, a biconcave negative lens L3, an optical path branching member OB, an optical path branching member OBx, an aperture stop STb, a meniscus positive lens Lb1 with its concave surface facing the object side, a meniscus negative lens Lb2 with its convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens Lb3 and a biconcave negative lens Lb4, and a biconvex positive lens Lb5.

[0356] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane Ib.

[0357] In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0358] In the first optical system OS1 of this embodiment, the positive lens Lb1, the negative lens Lb2, the cemented positive lens of the positive lens Lb3 and the negative lens Lb4, and the positive lens Lb5 are included in the first rear lens group GR1.

[0359] Table 8-2-1 below lists the specifications of the first optical system OS1 of this embodiment.

[0360] (Table 8-2-1) [Overall specifications] fA 2.09 TLA 71.81 FnoA 2.86 YmaxA 2.56 ωA 70.0° Wi 0.20 [Lens specifications] m r d n(d) νd 1) 39.16597 2.000 1.773 49.62 2) 18.66022 11.700 * 3) -38.70105 1.500 1.694 53.20 * 4) 13.43728 6.400 5) -32.89788 0.400 1.593 67.90 6) 14.35387 1.350 7) ∞ 13.000 1.569 56.00 (Optical path branching member OB) 8) ∞ 0.000 9) ∞ 13.000 1.569 56.00 (Optical path branching member OBx) 10) ∞ 0.570 11) ∞ 0.300 (Aperture stop STb) 12) -584.04520 0.730 1.744 44.80 13) -17.93216 0.100 14) 6.09856 3.885 1.755 27.57 15) 3.68968 0.650 16) 4.10048 5.500 1.519 69.89 17) -3.59835 1.100 1.755 27.57 18) 6.16444 0.300 *19) 5.60057 5.500 1.694 53.20 *20) -6.43550 3.824 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 3.95E-04 -2.07E-06 2.93E-09 5.51E-12 4) 0.2784 6.62E-04 -4.55E-06 3.07E-07 -1.97E-09 19) -0.2252 -1.17E-04 7.10E-05 -3.93E-06 3.88E-08 20) -2.8412 -1.16E-04 1.71E-04 -1.51E-05 1.11E-06 [Focal length data for each group] Group First surface Focal length GF 1 -4.45 GR1 12 13.33

[0361] FIG. 37 is a diagram showing various aberrations of the first optical system OS1 of the optical system of Example 8-2.

[0362] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0363] FIG. 38 is a cross-sectional view of the second optical system OS2 included in the optical system of Example 8-2.

[0364] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a biconcave negative lens L3, an optical path branching member OB, an aperture stop STM, a biconvex positive lens LM1, a meniscus negative lens LM2 with a convex surface facing the object side, a cemented positive lens of the biconvex positive lens LM3 and the meniscus negative lens LM3 with a concave surface facing the object side, an optical path branching member OBy, a cemented positive lens of the meniscus negative lens Lc1 with a convex surface facing the object side and the meniscus positive lens Lc2 with a convex surface facing the object side, a biconvex positive lens Lc3, and a cemented negative lens of the biconcave negative lens Lc4 and a biconvex positive lens Lc5.

[0365] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane Ic.

[0366] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0367] In the second optical system OS2 of this embodiment, the positive lens LM1, the negative lens LM2, the cemented positive lens of the positive lens LM3 and the negative lens LM4, the optical path branching member OBy, the cemented positive lens of the negative lens Lc1 and the positive lens Lc2, the positive lens Lc3, and the cemented negative lens of the negative lens Lc4 and the positive lens Lc5 are included in the second rear lens group GR2.

[0368] Table 8-2-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0369] (Table 8-2-2) [Overall specifications] fB 4.44 TLB 93.35 FnoB 2.13 YmaxB 2.26 ωB 30.0° [Lens specifications] m r d n(d) νd 1) 39.16597 2.000 1.773 49.62 2) 18.66022 11.700 * 3) -38.70105 1.500 1.694 53.20 * 4) 13.43728 6.400 5) -32.89788 0.400 1.593 67.90 6) 14.35387 1.350 7) ∞ 13.000 1.569 56.00 (Optical path splitter OB) 8) ∞ 2.000 9> ∞ 0.000 (Aperture stop STM) 10) 41.72564 5.000 1.603 60.69 11) -19.13995 0.120 12) 28.95936 1.000 1.744 44.80 13) 12.91167 0.300 14) 13.46515 5.000 1.498 82.57 15) -18.53975 0.350 1.744 44.80 16) -29.76038 8.990 17) ∞ 13.000 1.569 56.00 (Optical path splitter OBy) 18) ∞ 0.100 19) 10.30493 0.350 1.744 44.80 20) 6.39955 2.000 1.603 60.69 21) 16.50553 10.890 22) 7.20048 3.280 1.603 65.44 23) -9.50515 0.100 24) -9.57283 0.300 1.755 27.57 25) 4.00000 2.500 1.589 61.25 *26) -556.35436 1.724 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 3.95E-04 -2.07E-06 2.93E-09 5.51E-12 4) 0.2784 6.62E-04 -4.55E-06 3.07E-07 -1.97E-09 26) -4.5724 -9.34E-04 1.47E-04 6.10E-07 0.00E+00 [Focal length data for each group] Group Initial surface Focal length GF 1 -4.45 GR2 10 38.19

[0370] FIG. 39 is a diagram showing various aberrations of the second optical system OS2 of the optical system of Example 8-2.

[0371] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0372] Ninth Embodiment The optical system of this embodiment has the same overall configuration as the optical system of the eighth embodiment shown in FIG.

[0373] An optical system having an optical system OSa including a front lens group GF, an optical path branching member OB, an optical path branching member OBx, and a lens group Ga as a first optical system OS1, and an optical system OSd including a front lens group GF, an optical path branching member OB, an intermediate lens group GM, an optical path branching member OBy, and a lens group Gd as a second optical system OS2 is referred to as the optical system of Example 9-1. In the optical system of Example 8-1, the lens group Ga corresponds to the first rear lens group GR1, and the intermediate lens group GM, the optical path branching member OBy, and the lens group Gd correspond to the second rear lens group GR2. In the optical system of Example 9-1, the second optical system OS2 has an overall system focal length longer than the overall system focal length of the first optical system OS1. In other words, the first optical system OS1 corresponds to a wide-angle side optical system, and the second optical system OS2 corresponds to a telephoto side optical system.

[0374] An optical system having an optical system OSb including a front lens group GF, an optical path branching member OB, an optical path branching member OBx, and a lens group Gb as a first optical system OS1, and an optical system OSc including a front lens group GF, an optical path branching member OB, an intermediate lens group GM, an optical path branching member OBy, and a lens group Gc as a second optical system OS2 is referred to as the optical system of Example 9-2. In the optical system of Example 8-2, the lens group Gb corresponds to the first rear lens group GR1, and the intermediate lens group GM, the optical path branching member OBy, and the lens group Gc correspond to the second rear lens group GR2. In the optical system of Example 9-2, the second optical system OS2 has an overall system focal length longer than the overall system focal length of the first optical system OS1. In other words, the first optical system OS1 corresponds to a wide-angle side optical system, and the second optical system OS2 corresponds to a telephoto side optical system.

[0375] The front lens group GF, optical path branching member OB, optical path branching member OBx, lens group Ga, and lens group Gb of this embodiment are the same as the front lens group GF, optical path branching member OB, optical path branching member OBx, lens group Ga, and lens group Gb of Example 8. That is, the first optical system OS1 of Example 9-1 and the first optical system OS1 of Example 9-2 are the same as the first optical system OS1 of Example 8-1 and the first optical system OS1 of Example 8-2, respectively. Therefore, descriptions of the configurations and aberration diagrams of these optical systems will be omitted.

[0376] (Example 9-1)

[0377] FIG. 40 is a cross-sectional view of the second optical system OS2 included in the optical system of Example 9-1.

[0378] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a biconcave negative lens L3, an optical path branching member OB, a biconvex positive lens LM1, an aperture stop STM, a meniscus negative lens LM2 with a convex surface facing the object side, a cemented positive lens of a biconvex positive lens LM3 and a meniscus negative lens LM4 with a concave surface facing the object side, an optical path branching member OBy, a cemented negative lens of a biconcave negative lens Ld1 and a biconvex positive lens Ld2, and a cemented positive lens of a meniscus negative lens Ld3 with a convex surface facing the object side and a biconvex positive lens Ld4.

[0379] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane Id.

[0380] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0381] In the second optical system OS2 of this embodiment, the positive lens LM1, the aperture stop STM, the negative lens LM2, the cemented positive lens of the positive lens LM3 and the negative lens LM4, the optical path branching member OBy, the cemented negative lens of the negative lens Ld1 and the positive lens Ld2, and the cemented positive lens of the negative lens Ld3 and the positive lens Ld4 are included in the second rear lens group GR2.

[0382] Table 9-1-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0383] (Table 9-1-2) [Overall specifications] fB 13.15 TLB 143.34 FnoB 6.34 YmaxB 2.26 ωB 10.0° [Lens specifications] m r d n(d) νd 1) 39.16597 2.000 1.773 49.62 2) 18.66022 11.700 * 3) -38.70105 1.500 1.694 53.20 * 4) 13.43728 6.400 5) -32.89788 0.400 1.593 67.90 6) 14.35387 1.350 7) ∞ 26.000 1.569 56.00 (Optical path splitter OB) 8) ∞ 0.300 9) 42.94581 2.330 1.603 60.69 10) -19.44804 0.100 11) ∞ 0.100 (Aperture stop STM) 12) 24.51982 3.900 1.744 44.80 13) 11.82353 0.100 14) 10.94909 3.660 1.498 82.57 15) -12.75472 0.350 1.744 44.80 16) -96.09217 2.830 17) ∞ 14.000 1.569 56.00 (Optical path splitter OBy) 18) ∞ 2.820 19) -83.25237 0.400 1.744 44.80 20) 9.82815 3.000 1.620 36.40 21) -33.60000 52.050 22) 18.65139 0.350 1.755 27.57 23) 4.22340 5.500 1.498 82.57 24) -6.86700 2.204 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 3.95E-04 -2.07E-06 2.93E-09 5.51E-12 4) 0.2784 6.62E-04 -4.55E-06 3.07E-07 -1.97E-09 [Focal length data for each group] Group First surface Focal length GF 1 -4.45 GR2 9 -7.91

[0384] FIG. 41 is a diagram showing various aberrations of the second optical system OS2 of the optical system of Example 9-1.

[0385] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0386] Example 9-2 FIG. 42 is a cross-sectional view of the second optical system OS2 of the optical system of Example 9-2.

[0387] The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, a biconcave negative lens L3, an optical path branching member OB, a biconvex positive lens LM1, an aperture stop STM, a meniscus negative lens LM2 with a convex surface facing the object side, a cemented positive lens of a biconvex positive lens LM3 and a meniscus negative lens LLM4 with a concave surface facing the object side, an optical path branching member OBy, a cemented positive lens of a meniscus negative lens Lc1 with a convex surface facing the object side and a biconvex positive lens Lc2, and a cemented positive lens of a meniscus negative lens Lc3 with a convex surface facing the object side and a biconvex positive lens Lc4.

[0388] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane Ic.

[0389] In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the negative lens L3 are included in the front lens group GF.

[0390] In the second optical system OS2 of this embodiment, the positive lens LM1, the negative lens LM2, the cemented positive lens of the positive lens LM3 and the negative lens LM4, the optical path branching member OBy, the cemented positive lens of the negative lens Lc1 and the positive lens Lc2, and the cemented positive lens of the negative lens Lc3 and the positive lens Lc4 are included in the second rear lens group GR2.

[0391] Table 9-2-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0392] (Table 9-2-2) [Overall specifications] fB 4.40 TLB 103.27 FnoB 2.24 YmaxB 2.26 ωB 30.0° [Lens specifications] m r d n(d) νd 1) 39.16597 2.000 1.773 49.62 2) 18.66022 11.700 * 3) -38.70105 1.500 1.694 53.20 * 4) 13.43728 6.400 5) -32.89788 0.400 1.593 67.90 6) 14.35387 1.350 7) ∞ 26.000 1.569 56.00 (Optical path splitter OB) 8) ∞ 0.300 9) 42.94581 2.330 1.603 60.69 10) -19.44804 0.100 11) ∞ 0.100 (Aperture stop STM) 12) 24.51982 3.900 1.744 44.80 13) 11.82353 0.100 14) 10.94909 3.660 1.498 82.57 15) -12.75472 0.350 1.744 44.80 16) -96.09217 2.830 17) ∞ 14.000 1.569 56.00 (Optical path splitter OBy) 18) ∞ 0.100 19) 19.80441 0.350 1.744 44.80 20) 7.06065 3.000 1.581 40.98 21) -91.20537 14.735 22) 23.62158 0.350 1.755 27.57 23) 4.00000 2.660 1.589 61.25 *24) -10.42435 5.052 [Aspheric data] m K A4 A6 A8 A10 3) 5.7420 3.95E-04 -2.07E-06 2.93E-09 5.51E-12 4) 0.2784 6.62E-04 -4.55E-06 3.07E-07 -1.97E-09 24) 3.4924 1.33E-04 9.88E-06 8.35E-08 -9.66E-08 [Focal length data for each group] Group Initial surface Focal length GF 1 -4.45 GR2 9 153.04

[0393] FIG. 43 is a diagram showing various aberrations of the second optical system OS2 of the optical system of Example 9-2.

[0394] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0395] In the optical system 1 of Example 10, the second optical system OS2 has an overall focal length longer than the overall focal length of the first optical system OS1. That is, the first optical system OS1 corresponds to the wide-angle side optical system, and the second optical system OS2 corresponds to the telephoto side optical system.

[0396] FIG. 44 is a cross-sectional view of the first optical system OS1 included in the optical system 1 of the tenth example.

[0397] The first optical system OS1 of this embodiment has, in order from the object side, a meniscus-shaped negative lens L1 with a convex surface facing the object side, a meniscus-shaped negative lens L2 with a convex surface facing the object side, an optical path branching member OB, an aperture stop ST1, a meniscus-shaped positive lens L11 with a concave surface facing the object side, a meniscus-shaped negative lens L12 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L13 and a biconcave negative lens L14, and a meniscus-shaped positive lens L15 with a convex surface facing the object side.

[0398] A first image pickup element (not shown) made up of a CCD, CMOS or the like is disposed on the image plane I1.

[0399] In the first optical system OS1 of this embodiment, the negative lens L1 and the negative lens L2 are included in the front lens group GF.

[0400] In the first optical system OS1 of this embodiment, the positive lens L11, the negative lens L12, the cemented positive lens of the positive lens L13 and the negative lens L14, and the positive lens L15 are included in the first rear lens group GR1.

[0401] Table 10-1 below lists the values ​​of the specifications of the first optical system OS1 of this embodiment.

[0402] (Table 10-1) [Overall specifications] fA 2.80 TLA 68.48 FnoA 3.01 YmaxA 2.28 ωA 45.0° Wi 0.40 [Lens specifications] m r d n(d) νd 1) 39.35335 1.500 1.773 49.62 2) 13.16971 3.620 3) 54.65836 1.500 1.618 63.34 4) 10.24103 3.750 5) ∞ 15.000 1.517 63.88 (Optical path branching member OB) 6) ∞ 20.150 7> ∞ 0.300 (Aperture stop ST1) 8) -33.44797 3.090 1.744 44.80 9) -19.90034 0.300 10) 9.22913 5.190 1.755 27.57 11) 7.29360 0.100 12) 5.06967 5.000 1.519 69.89 13) -4.98655 0.400 1.755 27.57 14) 8.28160 0.300 *15) 4.27050 5.500 1.694 53.20 *16) 11.53216 2.781 [Aspheric data] m K A4 A6 A8 A10 15) -0.5510 -7.61E-04 -1.43E-04 1.23E-05 -3.04E-07 16) -0.1419 -1.46E-04 -1.09E-04 1.55E-05 7.86E-07 [Focal length data for each group] Group Initial surface Focal length GF 1 -10.59 GR1 8 9.57

[0403] FIG. 45 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the tenth example.

[0404] From each aberration diagram, it can be seen that the first optical system OS1 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0405] FIG. 46 is a cross-sectional view of the second optical system OS2 included in the optical system 1 of the tenth example.

[0406] The second optical system OS2 of this embodiment has, in order from the object side, a meniscus negative lens L1 with its convex surface facing the object side, a meniscus negative lens L2 with its convex surface facing the object side, an optical path branching member OB, an aperture stop ST2, a meniscus negative lens L21 with its convex surface facing the object side, a biconvex positive lens L22, a biconvex positive lens L23, and a cemented negative lens consisting of a meniscus negative lens L24 with its convex surface facing the object side and a biconvex positive lens L25.

[0407] An image pickup element made up of a CCD, CMOS or the like is disposed on the image plane I2.

[0408] In the second optical system OS2 of this embodiment, the negative lens L1 and the negative lens L2 are included in the front lens group GF.

[0409] In the second optical system OS2 of this embodiment, the negative lens L21, the positive lens L22, the positive lens L23, and the cemented negative lens of the negative lens L24 and the positive lens L25 are included in the second rear lens group GR2.

[0410] Table 10-2 below lists the specifications of the second optical system OS2 of this embodiment.

[0411] (Table 10-2) [Overall specifications] fB 6.47 TLB 71.98 FnoB 3.94 YmaxB 2.26 ωB 20.0° [Lens specifications] m r d n(d) νd 1) 39.35335 1.500 1.773 49.62 2) 13.16971 3.620 3) 54.65836 1.500 1.618 63.34 4) 10.24103 3.750 5) ∞ 15.000 1.517 63.88 (Optical path branching member OB) 6) ∞ 12.660 7) ∞ 0.100 (Aperture stop ST2) 8) 33.53774 5.500 1.744 44.80 9) 14.64236 0.360 10) 47.95935 1.000 1.498 82.57 11) -25.09306 0.100 12) 12.03523 1.180 1.744 44.80 13) -169.40203 6.750 14) 37.30592 1.000 1.755 27.57 15) 6.38587 4.000 1.498 82.57 16) -34.22061 13.956 [Focal length data for each group] Group Initial surface Focal length GF 1 -10.59 GR2 8 16.01

[0412] FIG. 47 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the tenth example.

[0413] From each aberration diagram, it can be seen that the second optical system OS2 of this embodiment appropriately corrects various aberrations and has high optical performance.

[0414] According to each of the above embodiments, it is possible to realize an optical system that splits incident light and appropriately forms an image for each of the split light.

[0415] The values ​​corresponding to the conditional expressions in each example are shown below.

[0416] fA is the focal length of the entire system of the wide-angle side optical system, fB is the focal length of the entire system of the telephoto side optical system, fF is the focal length of the front lens group GF, f1 is the focal length of the lens in the front lens group GF that is located closest to the object, and D12 is the distance on the optical axis between the lens located closest to the object in the front lens group GF and the lens located adjacent to that lens on the image plane side.

[0417] TLA is the total optical length of the wide-angle side optical system, and TLB is the total optical length of the telephoto side optical system. r11 is the radius of curvature of the object-side lens surface of the lens located closest to the object in the front lens group GF, r12 is the radius of curvature of the image-side lens surface of the lens located closest to the object in the front lens group GF, and r21 is the radius of curvature of the object-side lens surface of the lens located adjacent to the image-side lens located closest to the object in the front lens group GF. ωA is the half angle of view of the wide-angle side optical system, and ωB is the half angle of view of the telephoto side optical system.

[0418] fpA is the composite focal length of the positive lens components arranged consecutively from the positive lens component located closest to the object in the rear lens group included in the wide-angle side optical system to the positive lens components arranged consecutively toward the image plane, and fpB is the composite focal length of the positive lens components arranged consecutively from the positive lens component located closest to the object in the rear lens group included in the telephoto side optical system. fRA is the focal length of the rear lens group included in the wide-angle side optical system, and fRB is the focal length of the rear lens group included in the telephoto side optical system.

[0419] where nd1 is the refractive index for the d-line of the lens located closest to the object in the front lens group GF, nd2 is the refractive index for the d-line of the lens located adjacent to the image plane side of the lens located closest to the object in the front lens group GF, and ndaveF is the average refractive index for the d-line of the lenses in the front lens group GF. Wi is the reflectance or transmittance when the optical path of the wide-angle side optical system is reflected or transmitted by the splitting surface BP.

[0420] [Conditional expression corresponding values] Example No. Conditional expression 1st 2nd 3rd 4th 5th 6th (1) fB / fA 6.843 8.691 6.260 6.039 6.768 3.429 (2) -fF / fA 3.800 2.670 2.233 5.576 3.182 3.842 (3) -fF / fB 0.555 0.307 0.357 0.923 0.470 1.120 (4) -f1 / fA 10.576 29.494 11.672 10.846 9.367 8.176 (5) -f1 / fB 1.546 3.393 1.864 1.796 1.384 2.384 (6) -D12 / f1 0.476 0.283 0.279 0.430 0.388 0.653 (7) TLB / TLA 1.097 1.554 1.887 0.992 1.590 1.072 (8) -(r12+r11) / (r12-r11) 1.396 2.537 2.427 1.307 1.479 1.422 (9) (r21+r12) / (r21-r12) 1.938 1.188 0.787 0.412 0.788 0.300 (10) D12 / fA 5.036 8.354 3.251 4.668 3.638 5.336 (11) D12 / fB 0.736 0.961 0.519 0.773 0.538 1.556 (12) ωA / ωB 9.048 9.700 7.800 9.100 9.100 4.525 (13) fpA / fpB 1.149 1.905 0.443 1.015 1.093 1.301 (14) |fRB / fRA| 5.230 1.206 3.041 4.421 42.160 1.428 (15) TLB / fA 41.726 75.880 40.917 46.401 41.681 39.006 (16) TLA / fB 5.558 5.619 3.464 7.744 3.872 10.608 (17) nd1 1.755 1.773 1.755 1.744 1). 1.618 1.694 1.618 1.487 1.553 1.618 (19) whereF 91.0° 91.0° 90.5° (21) ωB 10.5° 10.0° 10.0° 10.0° 10.0° 20.0° (22) Wi / (1-Wi) 0.250 0.1 0.1101 0.429 .

[0421] Example Number Conditional Expression 7 8-1 8-2 9-1 9-2 10 (1) fB / fA 3.412 8.696 2.121 8.813 2.104 2.308 (2) -fF / fA 3.894 2.983 2.128 2.983 2.128 3.780 (3) -fF / fB 1.141 0.343 1.003 0.339 1.011 1.637 (4) -f1 / fA 8.186 32.286 23.030 32.286 23.030 9.381 (5) -f1 / fB 2.399 3.713 10.856 3.664 10.947 4.064 (6) -D12 / f1 0.652 0.243 0.243 0.243 0.243 0.138 (7) TLB / TLA 1.187 1.642 1.300 1.977 1.438 1.051 (8) -(r12+r11) / (r12-r11) 1.422 2.820 2.820 2.820 2.820 2.006 (9) (r21+r12) / (r21-r12) 0.300 0.349 0.349 0.349 0.349 1.635 (10) D12 / fA 5.337 7.839 5.592 7.839 5.592 1.292 (11) D12 / fB 1.564 0.901 2.636 0.890 2.658 0.560 (12) ωA / ωB 4.500 9.100 2.333 9.100 2.333 2.250 (13) fpA / fpB 0.960 1.120 1.107 1.117 1.104 - (14) |fRB / fRA| 1.401 1.112 2.864 0.878 11.478 1.674 (15) TLB / fA 43.269 79.756 44.619 96.045 49.357 25.694 (16) TLA / fB 10.683 5.587 16.179 5.513 16.314 10.590 (17) nd1 1.755 1.773 1.773 1.773 1.773 1.773 (18) nd2 1.618 1.694 1.694 1.694 1.694 1.618 (19) ndaveF 1.709 1.686 1.686 1.686 1.686 1.695 (20) ωA 90.0° 91.0° 70.0° 91.0° 70.0° 45.0° (21) ωB 20.0° 10.0° 30.0° 10.0° 30.0° 20.0° (22) Wi / (1-Wi) 0.111 0.250 0.250 0.111 0.111 0.667.

[0422] The above examples show specific examples of the present invention, and the present invention is not limited to these. The following content can be appropriately adopted within the scope that does not impair the optical performance of the optical system of this embodiment.

[0423] The optical system of this embodiment may have an optical member such as a filter between the lens surface closest to the image plane and the image plane.

[0424] In the optical system of this embodiment, the lens surface may be spherical or flat, or may be aspherical. A spherical or flat lens surface is preferred because it facilitates lens processing and assembly adjustment, and prevents degradation of optical performance due to errors in processing and assembly adjustment. Furthermore, a spherical or flat lens surface is preferred because it minimizes degradation of imaging performance when the image plane is misaligned.

[0425] In the case where the lens surface is aspherical, the aspherical surface may be formed by grinding glass or by glass molding using a mold having an aspherical shape, or may be formed on the surface of a resin bonded to the surface of the glass. In addition, in the optical system of this embodiment, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

[0426] The lens surfaces of the lenses constituting the optical system of this embodiment may be coated with an anti-reflection coating that has high transmittance over a wide wavelength range, thereby reducing flare and ghosting and achieving high-contrast optical performance.

[0427] In the optical system of this embodiment, instead of providing an independent member as the aperture stop, the role of the lens frame or the like may be substituted.

[0428] Next, an optical device including the optical system 1 of this embodiment will be described with reference to Fig. 48. Fig. 48 is a schematic diagram of an optical device 10 including the optical system 1 of this embodiment.

[0429] The optical device 10 includes the optical system 1 of the first embodiment, an information processing device 2, a drive unit 3, a first image sensor IS1, and a second image sensor IS2.

[0430] The first and second image sensors IS1 and IS2 are image sensors configured with a CCD, a CMOS, or the like. In the optical device 10, the first and second image sensors IS1 and IS2 are disposed on image planes I1 and I2, respectively, of the optical system 1, and output image information corresponding to incident light. The information processing device 2 performs processing using the image information output by the first and second image sensors IS1 and IS2.

[0431] The driving unit 3 has, for example, an actuator, and changes the orientation of the optical system 1 in accordance with a control signal received from the information processing device 2. At this time, the information processing device 2 may generate the control signal based on image information representing the image of the wide-angle side optical system.

[0432] 49 is a diagram illustrating an example of the operation of the drive unit 3 in the optical device 10 of this embodiment. In the optical system 1 of Example 1, the first optical system OS1 that forms an image on image plane I1 is a wide-angle optical system, and the second optical system OS2 that forms an image on image plane I2 is a telephoto optical system. Therefore, the range represented by the image information PW1 output by the first image sensor IS1 is wider than the range represented by the image information PT1 output by the second image sensor IS2.

[0433] 49 , object OBJ is included in image information PW1 but not in image information PT1. The information processing device 2 detects object OBJ from image information PW1 and identifies the direction of object OBJ based on the position of object OBJ in image information PW1 and the focal length of first optical system OS1. The information processing device 2 then generates a control signal to drive unit 3 to change the orientation of optical system 1 so that the optical system 1 faces the identified object OBJ.

[0434] The optical device 10 can acquire image information PT2 including the object OBJ using the telephoto-side optical system of the optical system 1, the orientation of which has been changed by the driver 3 operating in accordance with such a control signal. In this way, the optical device 10 of this embodiment can appropriately change the orientation of the optical system 1 based on a wide range of situations represented in the image obtained by the wide-angle-side optical system.

[0435] The drive unit 3 may be configured to change the orientation of the optical system 1 by changing the orientation of the optical device 10 .

[0436] The optical device 10 may generate image information based on image information representing an image of the wide-angle side optical system and image information representing an image of the telephoto side optical system. Fig. 50 shows an example of image information generated by the optical device 10 of this embodiment.

[0437] The information processing device 2 generates an enlarged image PWE by enlarging a part of the image information PW3 representing the image of the wide-angle side optical system. The enlarged image PWE is an example of first image information obtained by enlarging a part of the image of the wide-angle side optical system.

[0438] The information processing device 2 generates a composite image PS including the enlarged image PWE and image information PT3 representing an image of the telephoto-side optical system. The image information PT3 is an example of second image information representing at least a portion of the image of the telephoto-side optical system. The information processing device 2 operates as a composition unit that composes the first image information and the second image information.

[0439] 50, the information processing device 2 generates an image with an angle of view between the angle of view of the wide-angle side optical system and the angle of view of the telephoto side optical system by enlarging image information PW3 representing the image of the wide-angle side optical system. By replacing the central image with an image obtained by enlarging image information PW3 representing the image of the wide-angle side optical system and using at least a portion of image information PT3 representing the image of the telephoto side optical system, a composite image PS with a clearly displayed central portion can be obtained. In this case, the information processing device 2 may generate the composite image PS using an image obtained by reducing at least a portion of image information PT3.

[0440] According to the composite image PS output by the optical device 10 of this embodiment, it is possible to compare the portion included in the image obtained by the wide-angle optical system with the portion included in the image obtained by the telephoto optical system.

[0441] Finally, an outline of a method for manufacturing the optical system 1 of this embodiment will be described with reference to Fig. 51. Fig. 51 is a flow chart showing an outline of the method for manufacturing the optical system 1 of this embodiment.

[0442] The first manufacturing method of the optical system 1 of this embodiment shown in FIG. 51 includes the following steps S1 to S4.

[0443] Step S1: Prepare a front lens group GF having negative refractive power, an optical path branching member OB having a branching surface BP, a first rear lens group GR1, and a second rear lens group GR2.

[0444] Step S2: The first optical system OS1 is arranged to include a front lens group GF, an optical path splitting member OB, and a first rear lens group GR1 onto which the first light reflected by the splitting surface BP is incident.

[0445] Step S3: The second optical system OS2 is arranged to include a front lens group GF, an optical path splitting member OB, and a second rear lens group GR2 onto which the second light transmitted through the splitting surface BP is incident.

[0446] Step S4: The second optical system OS2 is configured to have an overall focal length different from that of the first optical system OS1.

[0447] According to the manufacturing method of the optical system of this embodiment, it is possible to manufacture an optical system that splits incident light and appropriately forms an image from each of the split light.

[0448] It should be understood that those skilled in the art can make various changes, substitutions, and alterations thereto without departing from the spirit and scope of the present disclosure.

[0449] REFERENCE SIGNS LIST 1 Optical system OS1 First optical system OS2 Second optical system OB, OBx, OBy Optical path branching member BP, BPx, BPy Branching surface ST1, ST2, STM, STa, STb Aperture stop I1, I2, Ia, Ib, Ic, Id Image surface RAP1, RAP2, RAP3 Right-angle prism IS1 First imaging element IS2 Second imaging element 10 Optical device 2 Information processing device 3 Drive unit

Claims

1. An optical system comprising, in order from the object side, a front lens group having negative refractive power, an optical path branching member having a branching surface that transmits a portion of incident light and reflects at least a portion different from the portion of the incident light, and a first rear lens group into which a first light that is at least a portion of the light reflected at the branching surface is incident; and a second optical system comprising, in order from the object side, the front lens group, the optical path branching member, and a second rear lens group into which a second light that is at least a portion of the light transmitted by the branching surface is incident, wherein the second optical system has an overall focal length different from that of the first optical system.

2. The optical system according to claim 1, which satisfies the following condition: 1.20<fB / fA<13.00, where fB is the longer of the total focal length of the first optical system and the total focal length of the second optical system, and fA is the shorter of the total focal length of the first optical system and the total focal length of the second optical system.

3. The optical system according to claim 1 or 2, which satisfies the following condition: 0.20<-fF / fA<10.00, where fF is the focal length of the front lens group, and fA is the shorter of the total focal length of the first optical system and the total focal length of the second optical system.

4. The optical system according to any one of claims 1 to 3, which satisfies the following condition: 0.05<-fF / fB<3.50, where fF is the focal length of the front lens group, and fB is the longer of the total focal length of the first optical system and the total focal length of the second optical system.

5. The optical system according to any one of claims 1 to 4, which satisfies the following condition: 3.50 < -f1 / fA < -50.30, where f1 is the focal length of the lens in the front lens group that is arranged closest to the object, and fA is the shorter of the total focal length of the first optical system and the total focal length of the second optical system.

6. The optical system according to any one of claims 1 to 5, which satisfies the following condition: 0.25<-f1 / fB<15.00, where f1 is the focal length of the lens in the front lens group that is arranged closest to the object, and fB is the longer of the total focal length of the first optical system and the total focal length of the second optical system.

7. The optical system according to any one of claims 1 to 6, which satisfies the following conditional expression: 0.04 < -D12 / f1 < 1.50, where D12 is the distance on the optical axis between the image side lens surface of the lens located closest to the object side in the front lens group and the object side lens surface of the lens located adjacent to the image side of the lens located closest to the object side in the front lens group, and f1 is the focal length of the lens located closest to the object side in the front lens group.

8. The optical system according to any one of claims 1 to 7, which satisfies the following conditional expression: 0.30 < TLB / TLA < 3.50, where TLB is the total optical length of the optical system having a longer total system focal length out of the first optical system and the second optical system, and TLA is the total optical length of the optical system having a shorter total system focal length out of the first optical system and the second optical system.

9. The optical system according to any one of claims 1 to 8, which satisfies the following condition: 0.30<-(r12+r11) / (r12-r11)<4.70, where r12 is the radius of curvature of the lens surface on the image side of the lens arranged closest to the object side in the front lens group, and r11 is the radius of curvature of the lens surface on the object side of the lens arranged closest to the object side in the front lens group.

10. The optical system according to any one of claims 1 to 9, which satisfies the following condition: 0.10 < (r21 + r12) / (r21 - r12) < 3.30, where r21 is the radius of curvature of the object-side lens surface of the lens arranged adjacent to the image surface side of the lens arranged closest to the object side in the front lens group, and r12 is the radius of curvature of the image surface side lens surface of the lens arranged closest to the object side in the front lens group.

11. The optical system according to any one of claims 1 to 10, which satisfies the following conditional expression: 0.30 < D12 / fA < 11.30, where D12 is the distance on the optical axis between the image side lens surface of the lens arranged closest to the object side in the front lens group and the object side lens surface of the lens arranged adjacent to the image side of the lens arranged closest to the object side in the front lens group, and fA is the shorter of the total system focal length of the first optical system and the total system focal length of the second optical system.

12. The optical system according to any one of claims 1 to 11, which satisfies the following conditional expression: 0.07 < D12 / fB < 4.30, where D12 is the distance on the optical axis between the image side lens surface of the lens arranged closest to the object side in the front lens group and the object side lens surface of the lens arranged adjacent to the image side of the lens arranged closest to the object side in the front lens group, and fB is the longer of the total system focal length of the first optical system and the total system focal length of the second optical system.

13. The optical system according to any one of claims 1 to 12, which satisfies the following condition: 1.20 < ωA / ωB < 15.00, where ωA is the half angle of view of the optical system having a shorter total system focal length out of the first optical system and the second optical system, and ωB is the half angle of view of the optical system having a longer total system focal length out of the first optical system and the second optical system.

14. The optical system according to any one of claims 1 to 13, which satisfies the following conditional expression: 0.20 < fpA / fpB < 2.50, where fpA is a composite focal length of a positive lens component arranged continuously from the positive lens component arranged closest to the object to the image surface side in a rear lens group included in the optical system of the first optical system or the second optical system, which has a shorter total system focal length, among the first rear lens group and the second rear lens group, and fpB is a composite focal length of a positive lens component arranged continuously from the positive lens component arranged closest to the object to the image surface side in a rear lens group included in the optical system of the first optical system or the second optical system, which has a longer total system focal length, among the first rear lens group and the second rear lens group.

15. The optical system according to any one of claims 1 to 14, which satisfies the following conditional expression: 0.33 < |fRB / fRA| < 65.00, where fRB is the focal length of a rear lens group included in the optical system having a longer total system focal length among the first optical system and the second optical system, among the first rear lens group and the second rear lens group, and fRA is the focal length of a rear lens group included in the optical system having a shorter total system focal length among the first optical system and the second optical system, among the first rear lens group and the second rear lens group.

16. The optical system according to any one of claims 1 to 15, which satisfies the following conditional expression: 7.00 < TLB / fA < 110.00, where TLB is the total optical length of the optical system having the longer total system focal length of the first optical system or the second optical system, and fA is the shorter of the total system focal lengths of the first optical system and the second optical system.

17. The optical system according to any one of claims 1 to 16, which satisfies the following conditional expression: 0.30 < TLA / fB < 20.50, where TLA is the total optical length of the optical system having the shorter total system focal length of the first optical system or the second optical system, and fB is the longer of the total system focal lengths of the first optical system and the second optical system.

18. The optical system according to any one of claims 1 to 17, which satisfies the following condition: 1.70 < nd1 < 2.01, where nd1 is the refractive index for the d-line of the lens in the front lens group that is disposed closest to the object side.

19. The optical system according to any one of claims 1 to 17, which satisfies the following condition: 1.50 < nd2 < 2.01, where nd2 is the refractive index for the d-line of a lens that is arranged adjacent to the image plane side of the lens that is arranged closest to the object side in the front lens group.

20. The optical system according to any one of claims 1 to 19, which satisfies the following condition: 1.55 < ndaveF < 2.01, where ndaveF is the average refractive index for the d-line of the lenses in the front lens group.

21. The optical system according to any one of claims 1 to 20, which satisfies the following condition: 45° < ωA < 120°, where ωA is the half angle of view of the optical system having the shorter total system focal length out of the first optical system and the second optical system.

22. The optical system according to any one of claims 1 to 20, which satisfies the following condition: 3° < ωB < 30°, where ωB is the half angle of view of the optical system having the longer total focal length of either the first optical system or the second optical system.

23. The optical system according to any one of claims 1 to 22, which satisfies the following conditional expression: 0.10 < Wi / (1-Wi) ≦ 1.00, where Wi is the reflectance of the splitting surface when the optical path of the first optical system or the second optical system, which has a shorter total system focal length, is reflected by the splitting surface, and is the transmittance of the splitting surface when the optical path of the first optical system or the second optical system, which has a shorter total system focal length, is transmitted by the splitting surface.

24. An optical system described in any one of claims 1 to 23, wherein at least one of the first rear lens group and the second rear lens group comprises a second optical path branching member having a second branching surface that reflects a portion of the incident light and transmits at least a portion different from the portion of the incident light, a third rear lens group into which at least a portion of the light reflected by the second branching surface is incident, and a fourth rear lens group into which at least a portion of the light transmitted by the second branching surface is incident.

25. The optical system described in claim 24, wherein among the first rear lens group and the second rear lens group, the lens group having the second optical path branching member, the third rear lens group, and the fourth rear lens group has an intermediate lens group having positive refractive power between the optical path branching member and the second optical path branching member.

26. The optical system according to any one of claims 1 to 25, wherein the image plane of the first optical system and the image plane of the second optical system are disposed on the same plane.

27. The optical system according to claim 26, wherein the total focal length of the first optical system is longer than the total focal length of the second optical system.

28. The optical system described in claim 27, wherein the first optical system further comprises a first optical path changing member between the optical path branching member and an image plane, the first optical path changing member changing the optical path of the light reflected at the branching surface so as to be parallel to the optical path of the light transmitted at the branching surface, and a second optical path changing member changing the optical path of the light reflected at the branching surface changed by the first optical path changing member so as to shorten the distance between the optical path of the light transmitted at the branching surface and the optical path of the light reflected at the branching surface.

29. An optical instrument comprising an optical system according to any one of claims 1 to 28.

30. The optical device according to claim 29, further comprising a drive unit that changes the orientation of the optical system based on image information representing an image of the optical system having the shorter overall focal length out of the first optical system and the second optical system.

31. The optical device described in claim 30, wherein the driving unit changes the orientation of the optical system so that an object detected from the image information is within the angle of view of the optical system having the longer total focal length between the first optical system and the second optical system.

32. An optical device according to any one of claims 29 to 31, comprising a synthesis section which synthesizes first image information obtained by enlarging a portion of an image of the optical system having a shorter total system focal length out of the first optical system and the second optical system, and second image information which represents at least a portion of an image of the optical system having a longer total system focal length out of the first optical system and the second optical system.

33. A method for manufacturing an optical system having a branching surface that transmits a portion of incident light and reflects at least a portion different from the portion of the incident light, and which images a first light that is at least a portion of the light reflected by the branching surface and a second light that is at least a portion of the light transmitted by the branching surface, comprising: arranging a first optical system to include, in order from the object side, a front lens group having negative refractive power, an optical path branching member having the branching surface, and a first rear lens group into which the first light is incident; arranging a second optical system to include, in order from the object side, the front lens group, the optical path branching member, and a second rear lens group into which the second light is incident; and configuring the second optical system to have an overall system focal length different from an overall system focal length of the first optical system.