WO2024010090A1

WO2024010090A1 - Optical system, optical device, and method for manufacturing optical system

Info

Publication number: WO2024010090A1
Application number: PCT/JP2023/025321
Authority: WO
Inventors: 孝道倉茂
Original assignee: 株式会社ニコン
Priority date: 2022-07-07
Filing date: 2023-07-07
Publication date: 2024-01-11

Abstract

This optical system comprises: a first optical system having a front lens group, a prism having a branching surface that branches incident light, and a first rear lens group on which the light having a longer optical path length when passing through the prism from among the branched lights is incident; and a second optical system having a front lens group, a prism, and a second rear lens group on which the light having a shorter optical path length when passing through the prism from among the branched lights is incident. The optical system is configured so as to satisfy the following conditional expression.　0.80 < -f(gr1n)/f(L) < 4.30 Here, f(gr1n) is the combined focal length of the negative lenses, from among the negative lenses included in the front lens group, that are disposed continuously to an image surface side from the negative lens disposed closest to the object side, and f(L) is the focal length of the first optical system.

Description

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

The present disclosure relates to an optical system, an optical device, and a method for manufacturing an optical system.

An optical system has been proposed that separates incident light into first light and second light and outputs them (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2006-324810

The optical system of the present disclosure includes, in order from the object side, a front lens group, a prism having a branching surface that transmits part of the incident light and reflects at least another part different from the part of the incident light; a first optical system having a first rear lens group into which light having a longer optical path length when passing through a prism enters among the transmitted light and the reflected light; and a front lens in order from the object side. a second optical system having a prism, and a second rear lens group into which light having a shorter optical path length when passing through the prism among the transmitted light and the reflected light is incident. and satisfy the following conditional expressions.
(1) 0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): First optical system focal length of

The method for manufacturing an optical system of the present disclosure includes, in order from the object side, a front lens group and a branching surface that transmits a part of the incident light and reflects at least another part of the incident light that is different from the part of the incident light. a first optical system having a prism, and a first rear lens group into which light having a longer optical path length when passing through the prism among transmitted light and reflected light enters; a second optical system including, in order, a front lens group, a prism, and a second rear lens group into which light having a shorter optical path length when passing through the prism among transmitted light and reflected light is incident; A method of manufacturing an optical system including a lens group and a prism, in which each lens group and prism are arranged so as to satisfy the following conditional expression.
(1) 0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): First optical system focal length of

FIG. 2 is a schematic diagram illustrating a schematic configuration of an optical system of a first example. FIG. 3 is a cross-sectional view of the first optical system included in the optical system of the first embodiment. FIG. 3 is a diagram showing various aberrations of the first optical system included in the optical system of the first example. FIG. 3 is a sectional view of a second optical system included in the optical system of the first embodiment. FIG. 7 is a diagram showing various aberrations of the second optical system included in the optical system of the first embodiment. FIG. 7 is a cross-sectional view of the first optical system included in the optical system of the second embodiment. FIG. 7 is a diagram showing various aberrations of the first optical system included in the optical system of the second example. FIG. 7 is a cross-sectional view of a second optical system included in the optical system of the second embodiment. FIG. 7 is a diagram showing various aberrations of the second optical system included in the optical system of the second example. FIG. 7 is a cross-sectional view of the first optical system included in the optical system of the third embodiment. FIG. 7 is a diagram showing various aberrations of the first optical system included in the optical system of the third example. FIG. 7 is a cross-sectional view of a second optical system included in the optical system of the third embodiment. FIG. 7 is a diagram showing various aberrations of the second optical system included in the optical system of the third example. FIG. 1 is a schematic diagram of an optical device equipped with an optical system of this embodiment. 1 is a flowchart illustrating an outline of a method for manufacturing an optical system according to the present embodiment.

Hereinafter, an optical system, an optical device, and a method for manufacturing the optical system according to an embodiment of the present application will be described.

The optical system of this embodiment includes, in order from the object side, a front lens group, and a prism having a branching surface that transmits a part of the incident light and reflects at least another part that is different from the part of the incident light. , a first rear lens group into which the light having the longer optical path length when passing through the prism among the transmitted light and the reflected light is incident; a second optical system having a lens group, a prism, and a second rear lens group into which light having a shorter optical path length when passing through the prism among the transmitted light and the reflected light enters; and satisfies the following conditional expression.
(1) 0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): First optical system focal length of

In the optical system of this embodiment, the entire optical system can be downsized by using the front lens group in the first optical system and the second optical system.

Conditional expression (1) is the composite focal length of the negative lens placed closest to the object side among the negative lenses included in the front lens group, and the negative lens placed successively on the image plane side, and of the first optical system. Define the ratio to the focal length. By satisfying conditional expression (1), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object, and appropriately reduces various aberrations such as field curvature, astigmatism, and distortion. Can be corrected.

In the optical system of this embodiment, when the value of conditional expression (1) exceeds the upper limit, the lens diameter of the lens closest to the object becomes too large, and various aberrations such as field curvature, astigmatism, and distortion are corrected. becomes difficult.

In the optical system of this embodiment, by setting the upper limit of conditional expression (1) to 4.30, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (1) to 3.80, 3.35, and further 2.90.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (1) is below the lower limit, the total optical length of the second optical system becomes too large, and it becomes difficult to correct various aberrations such as spherical aberration and coma aberration. . Furthermore, the peripheral light flux of the first optical system is restricted, and the amount of peripheral light is reduced. Note that in the present disclosure, the optical total length is the length obtained by adding the back focus in air equivalent length to the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane side.

In the optical system of this embodiment, by setting the lower limit of conditional expression (1) to 0.80, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (1) to 1.10, 1.40, and further 1.70.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(2) 1.10 < T(pL)/T(pS) < 5.50
however,
T (pL): Length of the prism on the optical axis in the first optical system T (pS): Length of the prism on the optical axis in the second optical system

Conditional expression (2) defines the ratio of the length of the prism on the optical axis in the first optical system to the length on the optical axis of the prism in the second optical system. By satisfying conditional expression (2), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration, and can secure the amount of peripheral light.

In the optical system of this embodiment, if the value of conditional expression (2) exceeds the upper limit, it becomes difficult to correct various aberrations such as spherical aberration and coma aberration.

In the optical system of this embodiment, by setting the upper limit of conditional expression (2) to 5.50, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (2) to 4.70, 3.80, and further 3.00.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (2) is below the lower limit, it becomes difficult to correct various aberrations such as spherical aberration and coma aberration. Furthermore, the peripheral light flux of the first optical system is restricted, and the amount of peripheral light is reduced.

In the optical system of this embodiment, by setting the lower limit of conditional expression (2) to 1.10, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (2) to 1.60, 2.10, and further 2.60.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(3) 0.50 < -f(gr1n)/f(S) < 4.40
however,
f(S): Focal length of the second optical system

Conditional expression (3) is the composite focal length of the negative lens placed closest to the object side among the negative lenses included in the front lens group and the negative lens placed successively on the image plane side, and the second optical system. This defines the ratio to the focal length. By satisfying conditional expression (3), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object, and appropriately reduces various aberrations such as field curvature, astigmatism, and distortion. Can be corrected.

In the optical system of this embodiment, if the value of conditional expression (3) exceeds the upper limit, the lens diameter of the lens closest to the object becomes too large, and various aberrations such as field curvature, astigmatism, and distortion are corrected. becomes difficult.

In the optical system of this embodiment, by setting the upper limit of conditional expression (3) to 4.40, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (3) to 4.00, 3.70, and further 3.40.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (3) is below the lower limit, it becomes difficult to correct various aberrations such as field curvature, astigmatism, and distortion.

In the optical system of this embodiment, by setting the lower limit of conditional expression (3) to 0.50, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (3) to 0.80, 1.15, and further 1.50.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(4) 0.40 < TL(L)/TL(S) < 3.50
however,
TL(L): Optical total length of the first optical system TL(S): Optical total length of the second optical system

Conditional expression (4) defines the ratio of the total optical length of the first optical system to the total optical length of the second optical system. By satisfying conditional expression (4), the optical system of this embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration while suppressing an increase in the total optical length of the optical system.

If the value of conditional expression (4) exceeds the upper limit in the optical system of this embodiment, the total optical length of the first optical system becomes too large, and it becomes difficult to correct various aberrations such as spherical aberration and coma aberration.

In the optical system of this embodiment, by setting the upper limit of conditional expression (4) to 3.50, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (4) to 2.80, 2.20, and further 1.60.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (4) is below the lower limit, the total optical length of the second optical system becomes too large, and it becomes difficult to correct various aberrations such as spherical aberration and coma aberration. .

In the optical system of this embodiment, by setting the lower limit of conditional expression (4) to 0.40, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (4) to 0.60, 0.80, and even 1.00.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(5) 0.01 < -f(gr1n)/f(gr1p) < 0.21
however,
f(gr1p): Synthetic focal length of the positive lens placed closest to the object side among the positive lenses included in the front lens group and the positive lens placed successively on the image plane side.

Conditional expression (5) is the composite focal length of the negative lens that is placed in succession from the negative lens that is placed closest to the object side to the image plane side among the negative lenses that are included in the front lens group, and the negative lens that is included in the front lens group. This defines the ratio of the positive lens placed closest to the object side to the composite focal length of the positive lenses placed successively on the image plane side. By satisfying conditional expression (5), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object, appropriately corrects various aberrations such as field curvature and distortion, and also It is possible to reduce the difficulty in manufacturing a branch surface having the performance of

In the optical system of this embodiment, when the value of conditional expression (5) exceeds the upper limit, the angle of incidence on the branching surface becomes too large, making it difficult to manufacture a branching surface with a predetermined performance.

In the optical system of this embodiment, by setting the upper limit of conditional expression (5) to 0.21, the effects of this embodiment can be made more reliable. Furthermore, in order to ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.18, 0.15, and even 0.12.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (5) falls below the lower limit, the refractive power of the front lens group becomes weak, the lens diameter of the lens closest to the object becomes too large, and the field curvature occurs. , it becomes difficult to correct various aberrations such as distortion.

In the optical system of this embodiment, by setting the lower limit of conditional expression (5) to 0.01, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (5) to 0.02, 0.03, and even 0.04.

Further, in the optical system of this embodiment, it is preferable that the second rear lens group has an aperture stop and satisfies the following conditional expression.
(6) 0.50 < f(gr2S)/(-f(gr1)) < 3.40
however,
f(gr2S): Composite focal length of the lens closer to the image plane than the aperture stop in the second rear lens group f(gr1): Composite focal length of the front lens group

Conditional expression (6) defines the ratio between the composite focal length of the lens on the image plane side of the aperture stop in the second rear lens group and the composite focal length of the front lens group. By satisfying conditional expression (6), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object, suppresses an increase in the total optical length in the second optical system, and suppresses field curvature. Various aberrations such as , coma, and distortion can be appropriately corrected.

In the optical system of this embodiment, if the value of conditional expression (6) exceeds the upper limit, the refractive power of the lens on the image plane side of the aperture stop in the second optical system becomes weaker, and the total optical length becomes too large. It becomes difficult to correct various aberrations such as field curvature, coma aberration, and distortion aberration.

In the optical system of this embodiment, by setting the upper limit of conditional expression (6) to 3.40, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (6) to 3.10, 2.80, and further 2.50.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (6) falls below the lower limit, the refractive power of the front lens group becomes weak, the lens diameter of the lens closest to the object becomes too large, and the second optical It becomes difficult to correct various aberrations such as field curvature and distortion in the system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (6) to 0.50, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (6) to 0.65, 0.80, and further 0.95.

Further, in the optical system of this embodiment, it is preferable that the first rear lens group has an aperture stop and satisfies the following conditional expression.
(7) 0.40 < f(gr2L)/(-f(gr1)) < 4.20
however,
f(gr2L): Composite focal length of the lens closer to the image plane than the aperture stop in the first rear lens group f(gr1): Composite focal length of the front lens group

Conditional expression (7) defines the ratio of the composite focal length of the lenses closer to the image plane than the aperture stop in the first rear lens group and the composite focal length of the front lens group. By satisfying conditional expression (7), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object side, suppresses an increase in the total optical length in the first optical system, and suppresses field curvature. Various aberrations such as , coma, and distortion can be appropriately corrected.

In the optical system of this embodiment, if the value of conditional expression (7) exceeds the upper limit, the refractive power of the lens on the image plane side of the aperture stop in the first optical system becomes weaker, and the total optical length becomes too large. It becomes difficult to correct various aberrations such as field curvature, coma aberration, and distortion aberration.

In the optical system of this embodiment, by setting the upper limit of conditional expression (7) to 4.20, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (7) to 3.80, 3.50, and further 3.20.

Furthermore, in the optical system of this embodiment, if the value of conditional expression (7) falls below the lower limit, the refractive power of the front lens group becomes weak, the lens diameter of the lens closest to the object becomes too large, and the first optical It becomes difficult to correct various aberrations such as field curvature and distortion in the system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (7) to 0.40, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (7) to 0.75, 1.10, and further 1.45.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(8) 0.70 < f(lS)/(-f(gr1n)) < 5.90
however,
f(lS): Focal length of the lens closest to the image plane in the second rear lens group

Conditional expression (8) is based on the focal length of the lens closest to the image plane in the second rear lens group, and the focal length of the negative lens included in the front lens group that is located closest to the object side to the image plane side. This defines the ratio of the negative lens to the composite focal length of the negative lens arranged as follows. By satisfying conditional expression (8), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object, suppresses an increase in the total optical length in the second optical system, and suppresses field curvature. Various aberrations such as , coma, and distortion can be appropriately corrected.

In the optical system of this embodiment, if the value of conditional expression (8) falls below the upper limit, the refractive power of the lens closest to the image plane in the second optical system becomes weak, the total optical length becomes too large, and field curvature occurs. It becomes difficult to correct various aberrations such as , coma, and distortion.

In the optical system of this embodiment, by setting the upper limit of conditional expression (8) to 5.90, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (8) to 5.30, 4.80, and further 4.20.

In the optical system of this embodiment, if the value of conditional expression (8) falls below the lower limit, the refractive power of the front lens group becomes weak, the lens diameter of the lens closest to the object side becomes too large, and the second optical system It becomes difficult to correct various aberrations such as field curvature and distortion.

In the optical system of this embodiment, by setting the lower limit of conditional expression (8) to 0.70, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (8) to 1.00, 1.35, and further 1.70.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(9) 1.50 < f(lL)/(-f(gr1n)) < 7.70
however,
f(lL): Focal length of the lens closest to the image plane in the first rear lens group

Conditional expression (9) is based on the focal length of the lens closest to the image plane in the first rear lens group, and the focal length of the lens that is located closest to the object side among the negative lenses included in the front lens group. This defines the ratio of the negative lens to the composite focal length of the negative lens arranged as follows. By satisfying conditional expression (9), the optical system of this embodiment suppresses an increase in the lens diameter of the lens closest to the object side, suppresses an increase in the total optical length in the first optical system, and suppresses field curvature. Various aberrations such as , coma, and distortion can be appropriately corrected.

In the optical system of this embodiment, if the value of conditional expression (9) is less than the upper limit, the refractive power of the lens closest to the image plane in the first optical system becomes weak, the total optical length becomes too large, and field curvature occurs. It becomes difficult to correct various aberrations such as , coma, and distortion.

In the optical system of this embodiment, by setting the upper limit of conditional expression (9) to 7.70, the effects of this embodiment can be made more reliable. Furthermore, in order to ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (9) to 6.30, 5.00, and further 3.90.

In the optical system of this embodiment, if the value of conditional expression (9) falls below the lower limit, the refractive power of the front lens group becomes weak, the lens diameter of the lens closest to the object becomes too large, and the first optical system It becomes difficult to correct various aberrations such as field curvature and distortion.

In the optical system of this embodiment, by setting the lower limit of conditional expression (9) to 1.50, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (9) to 1.70, 1.90, and even 2.10.

Further, in the optical system of this embodiment, it is preferable that the second rear lens group has an aperture stop and satisfies the following conditional expression.
(10) 1.60 < f(gr2S)/f(S) < 5.60
however,
f(gr2S): Combined focal length of the lens closer to the image plane than the aperture stop in the second rear lens group f(S): Focal length of the second optical system

Conditional expression (10) defines the ratio between the composite focal length of the lens on the image plane side of the aperture stop in the second rear lens group and the focal length of the second optical system. By satisfying conditional expression (10), the optical system of this embodiment suppresses an increase in the total optical length in the second optical system, and appropriately corrects various aberrations such as spherical aberration, coma aberration, and curvature of field. be able to.

In the optical system of this embodiment, if the value of conditional expression (10) falls below the upper limit, the refractive power of the lens on the image plane side of the aperture stop in the second optical system becomes weaker, and the total optical length becomes too large. It becomes difficult to correct various aberrations such as spherical aberration, coma aberration, and curvature of field.

In the optical system of this embodiment, by setting the upper limit of conditional expression (10) to 5.60, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (10) to 5.00, 4.50, and further 3.90.

In the optical system of this embodiment, when the value of conditional expression (10) is less than the lower limit value, the refractive power of the lens on the image plane side is stronger than the aperture stop in the second optical system, and spherical aberration and It becomes difficult to correct various aberrations such as coma aberration and curvature of field.

In the optical system of this embodiment, by setting the lower limit of conditional expression (10) to 1.60, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (10) to 2.00, 2.40, and further 2.80.

Further, in the optical system of this embodiment, it is preferable that the first rear lens group has an aperture stop and satisfies the following conditional expression.
(11) 2.30 < f(gr2L)/f(L) < 8.80
however,
f(gr2L): Composite focal length of the lens closer to the image plane than the aperture stop in the first rear lens group f(L): Focal length of the first optical system

Conditional expression (11) defines the ratio of the combined focal length of the lens closer to the image plane than the aperture stop in the first rear lens group and the focal length of the first optical system. By satisfying conditional expression (11), the optical system of this embodiment suppresses an increase in the total optical length in the first optical system, and appropriately corrects various aberrations such as spherical aberration, coma aberration, and curvature of field. be able to.

In the optical system of this embodiment, if the value of conditional expression (11) falls below the upper limit, the refractive power of the lens on the image plane side of the aperture stop in the first optical system becomes weaker, and the total optical length becomes too large. It becomes difficult to correct various aberrations such as spherical aberration, coma aberration, and curvature of field.

In the optical system of this embodiment, by setting the upper limit of conditional expression (11) to 8.80, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (11) to 8.00, 7.20, and further 6.40.

In the optical system of this embodiment, when the value of conditional expression (11) is less than the lower limit value, the refractive power of the lens on the image plane side is stronger than the aperture stop in the first optical system, and spherical aberration and It becomes difficult to correct various aberrations such as coma aberration and curvature of field.

In the optical system of this embodiment, by setting the lower limit of conditional expression (11) to 2.30, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (11) to 3.00, 3.70, and further 4.30.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(12) 1.20 < T(pS)/f(S) < 6.40
however,
T(pS): Length of the prism on the optical axis in the second optical system f(S): Focal length of the second optical system

Conditional expression (12) defines the ratio between the length of the prism on the optical axis in the second optical system and the focal length of the second optical system. By satisfying conditional expression (12), the optical system of the present embodiment appropriately corrects various aberrations such as spherical aberration, coma aberration, and curvature of field while suppressing an increase in the total optical length in the second optical system. can do.

In the optical system of this embodiment, if the value of conditional expression (12) is less than the upper limit, the total optical length becomes too large in the second optical system, and various aberrations such as spherical aberration, coma aberration, and curvature of field cannot be corrected. It becomes difficult.

In the optical system of this embodiment, by setting the upper limit of conditional expression (12) to 6.40, the effects of this embodiment can be made more reliable. Furthermore, in order to ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (12) to 5.70, 5.00, and even 4.40.

If the value of conditional expression (12) in the optical system of this embodiment falls below the lower limit, it becomes difficult to correct various aberrations such as spherical aberration, coma aberration, and field curvature in the second optical system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (12) to 1.20, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (12) to 1.50, 1.80, and further 2.20.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(13) 2.40 < T(pL)/f(L) < 20.50
T(pL): Length of the prism on the optical axis in the first optical system f(L): Focal length of the first optical system

Conditional expression (13) defines the ratio between the length of the prism on the optical axis in the first optical system and the focal length of the second optical system. By satisfying conditional expression (13), the optical system of the present embodiment appropriately corrects various aberrations such as spherical aberration, coma aberration, and curvature of field while suppressing an increase in the total optical length in the first optical system. can do.

In the optical system of this embodiment, if the value of conditional expression (13) is less than the upper limit, the total optical length in the first optical system becomes too large and correction of various aberrations such as spherical aberration, coma aberration, and curvature of field becomes difficult. It becomes difficult.

In the optical system of this embodiment, by setting the upper limit of conditional expression (13) to 20.50, the effects of this embodiment can be made more reliable. Furthermore, in order to ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (13) to 19.00, 17.50, and further 16.50.

If the value of conditional expression (13) in the optical system of this embodiment falls below the lower limit, it becomes difficult to correct various aberrations such as spherical aberration, coma aberration, and field curvature in the first optical system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (13) to 2.40, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (13) to 3.20, 4.00, and further 4.80.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(14) 1.40 < T(gr1)/f(S) < 6.90
however,
T(gr1): Distance on the optical axis from the lens surface closest to the object side of the front lens group to the lens surface closest to the image plane of the front lens group f(S): Focal length of the second optical system

Conditional expression (14) defines the ratio of the distance on the optical axis from the lens surface closest to the object side of the front lens group to the lens surface closest to the image plane of the front lens group and the focal length of the second optical system. It is something to do. By satisfying conditional expression (14), the optical system of this embodiment suppresses an increase in the total optical length while appropriately correcting various aberrations such as spherical aberration, coma aberration, and curvature of field. can do.

In the optical system of this embodiment, if the value of conditional expression (14) is less than the upper limit, the total optical length becomes too large in the second optical system, and correction of various aberrations such as spherical aberration, coma aberration, and curvature of field becomes difficult. It becomes difficult.

In the optical system of this embodiment, by setting the upper limit of conditional expression (14) to 6.90, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (14) to 6.30, 5.70, and further 5.10.

If the value of conditional expression (14) in the optical system of this embodiment falls below the lower limit, it becomes difficult to correct various aberrations such as spherical aberration, coma aberration, and field curvature in the second optical system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (14) to 1.40, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (14) to 1.90, 2.40, and further 2.80.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(15) 1.00 < T(gr1)/f(L) < 9.80
however,
T(gr1): Distance on the optical axis from the lens surface closest to the object side of the front lens group to the lens surface closest to the image plane of the front lens group f(L): Focal length of the first optical system

Conditional expression (15) defines the ratio of the distance on the optical axis from the lens surface closest to the object side of the front lens group to the lens surface closest to the image plane of the front lens group and the focal length of the first optical system. It is something to do. By satisfying conditional expression (15), the optical system of this embodiment suppresses an increase in the total optical length while appropriately correcting various aberrations such as spherical aberration, coma aberration, and curvature of field. can do.

In the optical system of this embodiment, if the value of conditional expression (15) is less than the upper limit, the total optical length in the first optical system becomes too large and correction of various aberrations such as spherical aberration, coma aberration, and curvature of field becomes difficult. It becomes difficult.

In the optical system of this embodiment, by setting the upper limit of conditional expression (15) to 9.80, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (15) to 8.80, 7.80, and further 6.80.

If the value of conditional expression (15) in the optical system of this embodiment falls below the lower limit, it becomes difficult to correct various aberrations such as spherical aberration, coma aberration, and field curvature in the first optical system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (15) to 1.00, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (15) to 1.40, 1.80, and even 2.10.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(16) 1.50 < Nave(s) < 1.90
however,
Nave(s): Average refractive index for the s-line of the negative lens included in the front lens group

Conditional expression (16) defines the average refractive index for the s-line of the negative lens included in the front lens group. The optical system of this embodiment can appropriately correct various aberrations such as distortion and field curvature by satisfying conditional expression (16).

In the optical system of this embodiment, if the value of conditional expression (16) falls below the upper limit, the refractive power for the s-line of the negative lens included in the front lens group becomes too strong, resulting in various aberrations such as distortion and curvature of field. It becomes difficult to correct.

In the optical system of this embodiment, by setting the upper limit of conditional expression (16) to 1.90, the effects of this embodiment can be made more reliable. In order to further ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (16) to 1.84, 1.77, and further 1.70.

In the optical system of this embodiment, if the value of conditional expression (16) is below the lower limit, the refractive power for the s-line of the negative lens included in the front lens group becomes too weak, resulting in various aberrations such as distortion and curvature of field. It becomes difficult to correct.

In the optical system of this embodiment, by setting the lower limit of conditional expression (16) to 1.50, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (16) to 1.55, 1.57, 1.58, and further 1.60.

Further, in the optical system of this embodiment, it is preferable that the following conditional expression is satisfied.
(17) 0.23 < f(lS)/f(lL) < 1.50
however,
f(lS): Focal length of the lens closest to the image plane in the second rear lens group f(IL): Focal length of the lens closest to the image plane in the first rear lens group

Conditional expression (17) defines the ratio of the focal length of the lens closest to the image plane in the second rear lens group to the focal length of the lens closest to the image plane in the first rear lens group. . By satisfying conditional expression (17), the optical system of this embodiment can reduce the deviation of the imaging position on the image plane with respect to a predetermined angle of view in the first optical system and the second optical system.

In the optical system of this embodiment, if the value of conditional expression (17) falls below the upper limit, it becomes difficult to correct the distortion aberration of the first optical system and the second optical system so that their respective distortion aberrations approach each other. The deviation of the imaging position on the image plane with respect to a predetermined angle of view in the system becomes large.

In the optical system of this embodiment, by setting the upper limit of conditional expression (17) to 1.50, the effects of this embodiment can be made more reliable. Further, in order to ensure the effects of this embodiment, it is preferable to set the upper limit of conditional expression (17) to 1.40, 1.30, and further 1.20.

In the optical system of this embodiment, if the value of conditional expression (17) falls below the lower limit, it becomes difficult to correct the distortion aberration of the first optical system and the second optical system so that their respective distortion aberrations become close to each other. The deviation of the imaging position on the image plane with respect to a predetermined angle of view in the system becomes large.

In the optical system of this embodiment, by setting the lower limit of conditional expression (17) to 0.23, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (17) to 0.36, 0.49, and further 0.62.

Furthermore, in the optical system of this embodiment, it is preferable that the front lens group has negative refractive power.

In the optical system of this embodiment, by having such a configuration, it is possible to suppress an increase in the lens diameter of the lens closest to the object side.

Furthermore, in the optical system of this embodiment, it is preferable that the front lens group each have one or more positive lenses and one or more negative lenses.

By having such a configuration, the optical system of this embodiment can appropriately correct various aberrations such as field curvature and astigmatism.

Further, in the optical system of this embodiment, it is preferable that both of the following conditional expressions are satisfied.
(24) 80.0° < 2ωL
(25) 80.0° < 2ωS
however,
2ωL: Full angle of view of the first optical system 2ωS: Full angle of view of the second optical system

Conditional expression (24) defines the entire angle of view of the first optical system. The optical system of this embodiment can obtain an image representing a wide range by the first optical system by satisfying conditional expression (24).

In the optical system of this embodiment, if the value of conditional expression (24) is below the lower limit, it is not possible to obtain an image representing a wide range with the first optical system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (24) to 80.0°, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (24) to 84.00°, 87.00°, and further to 90.00°.

Conditional expression (25) defines the entire angle of view of the second optical system. The optical system of this embodiment can obtain an image representing a wider range by the second optical system by satisfying conditional expression (25).

In the optical system of this embodiment, if the value of conditional expression (25) is below the lower limit, it is not possible to obtain an image representing a wide range with the second optical system.

In the optical system of this embodiment, by setting the lower limit of conditional expression (25) to 80.0°, the effects of this embodiment can be made more reliable. Further, in order to further ensure the effects of this embodiment, it is preferable to set the lower limit value of conditional expression (25) to 84.00°, 87.00°, and further to 90.00°.

Furthermore, in the optical system of this embodiment, one of the transmitted light and the reflected light is visible light and the other is near-infrared light, and among the first optical system and the second optical system, Preferably, the optical system that uses visible light from the branching surface to the image plane side has a cemented lens, and the optical system that uses near-infrared light from the branching surface to the image plane side consists of only a single lens.

In the optical system of this embodiment, the optical system that uses visible light from the branching surface to the image plane side has a cemented lens, so that chromatic aberration can be appropriately corrected. Further, in the optical system of this embodiment, the optical system that uses near-infrared light from the branching surface to the image plane side is configured with only a single lens, so that the optical system can be miniaturized.

Furthermore, in the optical system of the present embodiment, the prism preferably includes a total reflection surface that totally reflects at least light on the optical axis among the light reflected by the branching surface after passing through the front lens group.

By having such a configuration, the optical system of this embodiment can reduce the angle of incidence of the incident light on the branching surface, and can reduce the difficulty in manufacturing a branching surface having a predetermined performance. .

With the above configuration, it is possible to realize an optical system that appropriately images each of the light transmitted by the branching surface and the light reflected by the branching surface among the incident light.

The optical device of this embodiment has an optical system configured as described above. As a result, it is possible to realize an optical device that can appropriately form images of the incident light transmitted by the branching surface and the light reflected by the branching surface, and perform processing using each image. can.

The method for manufacturing an optical system of the present disclosure includes, in order from the object side, a front lens group and a branching surface that transmits a part of incident light and reflects at least another part different from the part of the incident light. a first optical system having a prism and a first rear lens group into which light having a longer optical path length when passing through the prism among transmitted light and reflected light enters; , a second optical system having a front lens group, the prism, and a second rear lens group into which light having a shorter optical path length when passing through the prism is incident among the transmitted light and the reflected light. A method of manufacturing an optical system including a lens group and a prism, in which each lens group and prism are arranged so as to satisfy the following conditional expression.
(1) 0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): First optical system focal length of

By using such an optical system manufacturing method, it is possible to manufacture an optical system that appropriately images each of the incident light that is transmitted through the branching surface and the light that is reflected by the branching surface.

(Numerical example)
Embodiments of the present application will be described below based on the drawings.

(First example)
FIG. 1 is a schematic diagram illustrating the schematic configuration of the optical system of the first embodiment.

The optical system 1 of this embodiment includes, in order from the object side, a front lens group GR1, a prism P having a branching surface BF, and light that enters the front lens group GR1 and the prism P and is transmitted by the branching surface BF. It has a first optical system OS1 including a first rear lens group GR2L. In addition, the optical system 1 of this embodiment includes, in order from the object side, a front lens group GR1, a prism P, a second rear lens group into which light enters the front lens group GR1 and the prism P and is reflected by the branching surface BF. It has a second optical system OS2 including a side lens group GR2S. The light that enters the first rear lens group GR2L is the light that has a longer optical path length when passing through the prism P between the light that is transmitted by the branching surface BF and the light that is reflected. The light that enters the second rear lens group GR2S is the light that has a shorter optical path length when passing through the prism P between the light that is transmitted by the branching surface BF and the light that is reflected.

In FIG. 1, the first optical axis X1 of the first optical system OS1 and the second optical axis X2 of the second optical system OS2 are shown on the object side with respect to the branch plane BF so as not to overlap each other for the sake of explanation. .

In the optical system 1 of this embodiment, the prism P is a dichroic prism having a branching surface BF that transmits visible light and reflects near-infrared light. Visible light includes, for example, d-line (wavelength: 587.6 nm) or g-line (wavelength: 435.8 nm), and near-infrared light includes, for example, s-line (wavelength: 852.1 nm).

The first optical system OS1 of this embodiment images the light (near infrared light) emitted from the front lens group GR1 and reflected by the branching surface BF and the total reflection surface TRF of the prism P onto the image plane I1. . The second optical system OS2 of this embodiment images the light (visible light) emitted from the front lens group GR1 and transmitted through the branching surface BF of the prism P onto the image plane I2.

The optical system 1 of this embodiment appropriately controls the light reflected by the branching surface BF and the light transmitted by the branching surface BF out of the incident light by the first optical system OS1 and the second optical system OS2, respectively. It can be imaged.

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

The first optical system OS1 of this embodiment includes, in order from the object side, a meniscus-shaped negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, and a meniscus-shaped negative lens L2 with a concave surface facing the object side. A positive lens L3, a prism P, a biconvex positive lens L11, an aperture stop ST1, a meniscus positive lens L12 with a convex surface facing the object side, and a meniscus negative lens with a concave surface facing the object side. L13, and a biconvex positive lens L14.

An image sensor composed of a CCD, CMOS, or the like is arranged on the image plane I1.

A filter FL1 is arranged between the positive lens L14, which is arranged closest to the image plane I1, and the image plane I1.

In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the positive lens L3 are included in the front lens group GR1. Further, the positive lens L11, the aperture stop ST1, the positive lens L12, the negative lens L13, and the positive lens L14 are included in the first rear lens group GR2L.

Table 1-1 below lists the values of the specifications of the first optical system OS1 of this example. In [Lens specifications] in Table 1-1, m is the order of the optical surfaces 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 n(s) is The refractive index for the s-line and νd indicate the Abbe number for the d-line. The radius of curvature r=∞ indicates a plane. In addition, in [Lens specifications], optical surfaces marked with "*" indicate that they are aspheric surfaces.

In [Aspheric data], m is the optical surface corresponding to the aspheric data, K is the conic constant, and A4 to A10 are the aspheric coefficients.

The height of the aspherical surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangent plane of the vertex of each aspherical surface to each aspherical surface at the height y is S(y) When the radius of curvature (paraxial radius of curvature) of the reference sphere is r, the conic constant is K, and the nth-order aspherical coefficient is An, it is expressed by the following equation (a). Note that in each example, the second-order aspheric coefficient A2 is 0. Moreover, "En" indicates "×10 ^-n ".

(a) S(y) = (y ² /r) / { 1 + (1-K×y ² /r ² ) ^1/2 }
+ A4×y ⁴ + A6×y ⁶ + A8×y ⁸ + A10×y ¹⁰

In Table 1-1 [Overall specifications], Fno is the F value of the optical system, f is the focal length of the entire optical system, TL is the total optical length, Y is the image height, and 2ω is the total angle of view (degrees). . Note that these values described in [Overall specifications] are values for the d-line.

The units of focal length f, radius of curvature r, and other lengths listed in Table 1-1 are "mm". However, the optical system is not limited to this because the same optical performance can be obtained even if the optical system is proportionally enlarged or reduced.

The symbols in Table 1-1 described above are similarly used in the tables of the second optical system OS2 of this embodiment and other embodiments, which will be described later.

(Table 1-1)
[Lens specifications]
m r d n(d) νd ns
1) 23.24716 2.500 1.618 63.34 1.610
2) 8.85754 6.000
3) -62.73425 1.300 1.618 63.34 1.610
4) 10.07820 2.940
5) -62.37902 5.500 1.755 27.57 1.735
6) -30.02650 0.800
7) ∞ 32.500 1.517 63.88 1.510 (Prism P)
8) ∞ 0.230
9) 15.44687 2.850 1.835 42.73 1.819
10) -300.00000 1.400
11> ∞ 1.650 (Aperture stop ST1)
12) 10.79653 2.850 1.835 42.73 1.819
13) 350.00000 0.920
14) -15.64213 0.500 1.835 42.73 1.819
15) -83.64620 1.190
*16) 300.00000 4.150 1.835 42.73 1.819
*17) -25.21347 3.490
18) ∞ 0.210 1.517 63.88 1.510 (Filter FL1)
19) ∞ 0.343

[Aspheric data]
m K A4 A6 A8 A10
16) 9.2225 7.80E-05 2.38E-06 1.06E-06 -3.67E-08
17) -2.9888 4.80E-04 -1.15E-05 3.76E-06 -1.49E-07

[Overall specifications]
Fno 1.18
f2.81
TL 71.25
Y2.29
2ω 92.00

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

In each aberration diagram, the spherical aberration diagram (LONGITUDINAL SPHERICAL ABER.) shows the ratio to the maximum aperture, the astigmatism diagram (ASTIGMATIC FIELD CURVES) and distortion aberration diagram (DISTORTION) show the value of the half angle of view, and the coma aberration diagram shows the ratio to the maximum image height. Each aberration diagram shows s-line values. In the astigmatism diagram, S indicates a sagittal image plane, and T indicates a meridional image plane. In the aberration diagrams of other embodiments to be described later, the same symbols as in the aberration diagrams of this embodiment are used.

From each aberration diagram, it can be seen that the first optical system OS1 of this example appropriately corrects various aberrations and has high optical performance for s-line.

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

The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus-shaped negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, and a meniscus-shaped negative lens L2 with a concave surface facing the object side. A positive lens L3, a prism P, a meniscus-shaped positive lens L21 with a convex surface facing the object side, an aperture stop ST2, a meniscus-shaped positive lens L22 with a convex surface facing the object side, and a biconvex positive lens. It has a cemented negative lens L23 and a biconcave negative lens L24, a meniscus-shaped positive lens L25 with a convex surface facing the object side, and a meniscus-shaped positive lens L26 with a convex surface facing the object side. .

An image sensor composed of a CCD, CMOS, etc. is arranged on the image plane I2.

A filter FL2 is disposed between the positive lens L26, which is disposed closest to the image plane I2, and the image plane I2.

In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the positive lens L3 are included in the front lens group GR1. Further, the positive lens L21, the aperture stop ST2, the positive lens L22, the cemented negative lens of the positive lens L23 and the negative lens L24, the positive lens L25, and the positive lens L26 are included in the second rear lens group GR2S. included.

Table 1-2 below lists the values of the specifications of the second optical system OS2 of this example.

(Table 1-2)
[Lens specifications]
m r d n(d) νd
1) 23.24716 2.500 1.618 63.34
2) 8.85754 6.000
3) -62.73425 1.300 1.618 63.34
4) 10.07820 2.940
5) -62.37902 5.500 1.755 27.57
6) -30.02650 0.800
7) ∞ 11.000 1.517 63.88 (Prism P)
8) ∞ 0.150
9) 18.88785 5.650 1.700 48.10
10) 300.00000 1.540
11> ∞ 1.550 (Aperture stop ST2)
12) 14.36704 2.600 1.697 55.52
13) 313.89814 0.150
14) 15.11805 2.200 1.519 69.89
15) -25.38622 0.400 1.755 27.57
16) 9.06631 0.930
17) 9.42227 2.400 1.623 58.12
18) 42.81721 1.830
*19) 11.33584 4.500 1.623 58.12
*20) 23.57318 4.660
21) ∞ 0.500 1.517 63.88 (Filter FL2)
22) ∞ 0.359

[Aspheric data]
m K A4 A6 A8 A10
19) -1.1497 -7.48E-05 -1.27E-06 -8.15E-08 7.15E-10
20) -4.4220 8.96E-05 -2.30E-06 -3.03E-08 3.23E-10

[Overall specifications]
Fno 2.00
f 4.99
TL 59.29
Y4.01
2ω 92.00

FIG. 5 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the first embodiment. Each aberration diagram shows d-line and g-line values, respectively.

From each aberration diagram, it can be seen that the second optical system OS2 of this example appropriately corrects various aberrations and has high optical performance for the d-line and the g-line.

(Second example)
The optical system 1 of this embodiment has the same general configuration as the optical system 1 of the first embodiment described with reference to FIG.

In the optical system 1 of this embodiment, the prism P is a dichroic prism having a branching surface BF that transmits near-infrared light and reflects visible light.

The first optical system OS1 of this embodiment images the light (visible light) emitted from the front lens group GR1 and reflected by the branching surface BF and the total reflection surface TRF of the prism P onto the image plane I1. The second optical system OS2 of this embodiment images the light (near infrared light) emitted from the front lens group GR1 and transmitted through the branching surface BF of the prism P onto the image plane I2.

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

The first optical system OS1 of this embodiment includes, in order from the object side, a meniscus-shaped negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, and a meniscus-shaped negative lens L2 with a convex surface facing the object side. A positive lens L3, a prism P, a meniscus-shaped positive lens L11 with a convex surface facing the object side, an aperture stop ST1, a meniscus-shaped negative lens L12 with a convex surface facing the object side, and a biconvex positive lens. It has a cemented negative lens L13 and a biconcave negative lens L14, a meniscus positive lens L15 with a convex surface facing the object side, and a meniscus positive lens L16 with a convex surface facing the object side. .

A filter FL1 is arranged between the positive lens L16 disposed closest to the image plane I1 and the image plane I1.

In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the positive lens L3 are included in the front lens group GR1. Further, the positive lens L11, the aperture stop ST1, the negative lens L12, the cemented negative lens of the negative lens L13 and the positive lens L14, the positive lens L15, and the positive lens L16 are included in the first rear lens group GR2L. included.

Table 2-1 below lists the values of the specifications of the first optical system OS1 of this example.

(Table 2-1)
[Lens specifications]
m r d n(d) νd
1) 29.68900 1.200 1.640 60.19
2) 9.70090 5.000
3) -195.75730 1.200 1.618 63.34
4) 11.92140 1.550
5) 28.18830 2.000 1.755 27.57
6) 43.38750 1.000
7) ∞ 32.500 1.517 63.88 (Prism P)
8) ∞ 0.500
9) 12.82210 2.620 1.700 48.10
10) 302.64820 3.760
11> ∞ 0.100 (Aperture stop ST1)
12) 30.12150 0.955 1.651 56.24
13) 26.67870 0.100
14) 10.81720 2.710 1.519 69.89
15) -14.47040 0.350 1.755 27.57
16) 16.24750 0.100
17) 9.11660 1.150 1.620 60.24
18) 10.15080 1.039
*19) 14.74820 5.500 1.620 60.24
*20) 270.84350 1.000
21) ∞ 0.300 1.517 63.88 (Filter FL1)
22) ∞ 7.217

[Aspheric data]
m K A4 A6 A8 A10
19) -3.2435 -2.20E-04 -3.59E-06 3.52E-09 2.17E-10
20) 11.0000 -4.40E-05 -1.45E-06 4.57E-08 -2.20E-10

[Overall specifications]
Fno 2.10
f5.03
TL 71.75
Y 4.02
2ω 92.00

FIG. 7 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the second embodiment. Each aberration diagram shows d-line and g-line values, respectively.

From each aberration diagram, it can be seen that the first optical system OS1 of this example appropriately corrects various aberrations and has high optical performance for the d-line and the g-line.

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

The second optical system OS2 of this embodiment includes, in order from the object side, a meniscus-shaped negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, and a meniscus-shaped negative lens L2 with a convex surface facing the object side. A positive lens L3, a prism P, a meniscus-shaped negative lens L21 with a convex surface facing the object side, an aperture stop ST2, a biconvex positive lens L22, and a meniscus-shaped positive lens with a convex surface facing the object side. L23, and a biconvex positive lens L24.

In the second optical system OS2 of this embodiment, the negative lens L1, the negative lens L2, and the positive lens L3 are included in the front lens group GR1. Further, the negative lens L21, the aperture stop ST2, the positive lens L22, the positive lens L23, and the positive lens L24 are included in the second rear lens group GR2S.

Table 2-2 below lists the values of the specifications of the second optical system OS2 of this example.

(Table 2-2)
[Lens specifications]
m r d n(d) νd ns
1) 29.68897 1.200 1.640 60.20 1.631
2) 9.70092 5.000
3) -195.75734 1.200 1.618 63.34 1.610
4) 11.92145 1.550
5) 28.18828 2.000 1.755 27.57 1.735
6) 43.38751 1.000
7) ∞ 12.000 1.517 63.88 1.510 (Prism P)
8) ∞ 0.500
9) 16.64118 0.350 1.532 48.78 1.523
10) 9.69527 11.748
11> ∞ 0.100 (Aperture stop ST2)
12) 16.58651 3.000 1.755 27.57 1.735
13) -531.70077 4.273
14) 10.44070 5.497 1.755 27.57 1.735
15) 14.92879 0.647
*16) 13.31421 5.500 1.774 47.18 1.760
17) -128.00260 4.854

[Aspheric data]
m K A4 A6 A8 A10
16) -4.0120 -1.07E-04 -5.73E-06 1.74E-08 6.04E-10

[Overall specifications]
Fno 1.20
f2.77
TL 60.42
Y2.20
2ω 92.00

FIG. 9 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the second embodiment. Each aberration diagram shows s-line values.

From each aberration diagram, it can be seen that the second optical system OS2 of this example appropriately corrects various aberrations and has high optical performance for the s-line.

(Third example)
The optical system 1 of this embodiment has the same general configuration as the optical system 1 of the first embodiment described with reference to FIG.

In the optical system 1 of this embodiment, the prism P is a dichroic prism having a branching surface BF that transmits visible light and reflects near-infrared light.

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

The first optical system OS1 of this embodiment includes, in order from the object side, a meniscus-shaped negative lens L1 with a convex surface facing the object side, a biconcave negative lens L2, and a meniscus-shaped negative lens L2 with a concave surface facing the object side. A positive lens L3, a prism P, a biconvex positive lens L11, an aperture stop ST1, a meniscus positive lens L12 with a convex surface facing the object side, and a meniscus positive lens with a convex surface facing the object side. L13, a meniscus-shaped positive lens L14 with a convex surface facing the object side, and a meniscus-shaped positive lens L15 with a concave surface facing the object side.

A filter FL1 is arranged between the positive lens L15, which is arranged closest to the image plane I1, and the image plane I1.

In the first optical system OS1 of this embodiment, the negative lens L1, the negative lens L2, and the positive lens L3 are included in the front lens group GR1. Further, the positive lens L11, the aperture stop ST1, the positive lens L12, the positive lens L13, the positive lens L14, and the positive lens L15 are included in the first rear lens group GR2L.

Table 3-1 below lists the values of the specifications of the first optical system OS1 of this example.

(Table 3-1)
[Lens specifications]
m r d n(d) νd ns
1) 22.65975 2.000 1.603 60.69 1.595
2) 8.58484 6.013
3) -46.67377 0.800 1.519 69.89 1.512
4) 10.08192 3.049
5) -69.22039 2.313 1.755 27.57 1.735
6) -40.41329 0.988
7) ∞ 47.000 1.517 63.88 1.510 (Prism P)
8) ∞ 1.805
9) 33.91430 3.017 1.720 50.27 1.708
10) -66.06093 0.100
11> ∞ 0.100 (Aperture stop ST1)
12) 26.49772 2.147 1.623 58.12 1.614
13) 74.01188 0.100
14) 19.60218 2.271 1.593 67.90 1.586
15) 46.09410 0.100
16) 13.36196 2.584 1.487 70.31 1.481
17) 29.13116 4.967
*18) -19.16636 5.496 1.487 70.31 1.481
*19) -9.49217 0.182
20) ∞ 0.300 1.517 63.88 1.510 (Filter FL1)
21) ∞ 3.000

[Aspheric data]
m K A4 A6 A8 A10
18) -2.2395 -3.29E-04 3.25E-06 1.17E-07 -4.08E-09
19) 0.3196 -1.85E-05 1.28E-05 -1.34E-07 -8.44E-09

[Overall specifications]
Fno 1.20
f2.93
TL 88.00
Y2.29
2ω 92.00

FIG. 11 is a diagram showing various aberrations of the first optical system OS1 included in the optical system 1 of the third embodiment. Each aberration diagram shows s-line values.

From each aberration diagram, it can be seen that the first optical system OS1 of this example appropriately corrects various aberrations and has high optical performance with respect to the s-line.

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

Table 3-2 below lists the values of the specifications of the second optical system OS2 of this example.

(Table 3-2)
[Lens specifications]
m r d n(d) νd
1) 22.65975 2.000 1.603 60.69
2) 8.58484 6.013
3) -46.67377 0.800 1.519 69.89
4) 10.08192 3.049
5) -69.22039 2.313 1.755 27.57
6) -40.41329 0.988
7) ∞ 17.000 1.517 63.88 (Prism P)
8) ∞ 0.384
9) 15.15381 2.574 1.720 50.27
10) 516.88017 4.098
11> ∞ 0.100 (Aperture stop ST2)
12) 15.83971 2.165 1.651 56.24
13) 42.97328 0.100
14) 12.34848 2.119 1.519 69.89
15) -21.04824 0.350 1.755 27.57
16) 10.90829 0.100
17) 9.48441 2.289 1.620 60.24
18) 23.82029 1.297
*19) 12.79368 5.503 1.620 60.24
*20) 25.72131 1.000
21) ∞ 0.300 1.517 63.88 (Filter FL2)
22) ∞ 3.960

[Aspheric data]
m K A4 A6 A8 A10
19) -2.0024 -1.76E-04 -2.50E-06 -1.86E-08 3.06E-10
20) 11.0000 8.87E-05 -1.45E-06 1.92E-08 4.13E-09

[Overall specifications]
Fno 2.00
f 4.93
TL 58.40
Y4.01
2ω 92.00

FIG. 13 is a diagram showing various aberrations of the second optical system OS2 included in the optical system 1 of the third embodiment. Each aberration diagram shows d-line and g-line values, respectively.

According to each of the embodiments described above, it is possible to realize an optical system that appropriately images each of the light transmitted by the branching surface and the light reflected by the branching surface among the incident light.

Below, the values corresponding to the conditional expressions of each example are shown.

f(L) is the focal length of the first optical system OS1, and f(S) is the focal length of the second optical system OS2. TL(L) is the optical total length of the first optical system OS1, and TL(S) is the optical total length of the second optical system OS2.

f(gr1) is the composite focal length of the front lens group GR1. f(gr1n) is the composite focal length of the negative lens arranged in succession from the negative lens disposed closest to the object side to the image plane side among the negative lenses included in the front lens group GR1. f(gr1p) is the composite focal length of the positive lens arranged in succession from the positive lens disposed closest to the object side to the image plane side among the positive lenses included in the front lens group GR1. T(gr1) is the distance on the optical axis from the lens surface of the front lens group GR1 closest to the object side to the lens surface of the front lens group GR1 closest to the image plane.

T(pL) is the length of the prism on the optical axis in the first optical system OS1, and T(pS) is the length of the prism on the optical axis in the second optical system OS2.

f(gr2L) is the composite focal length of the lens closer to the image plane than the aperture stop ST1 in the first rear lens group GR2L, and f(gr2S) is the composite focal length of the lens closer to the image plane than the aperture stop ST2 in the second rear lens group GR2S. This is the composite focal length of the side lens.

f(lL) is the focal length of the lens closest to the image plane in the first rear lens group GR2L, and f(lS) is the focal length of the lens closest to the image plane in the second rear lens group GR2S.

Nave(s) is the average refractive index for the s-line of the negative lens included in the front lens group GR1. 2ωL is the total angle of view of the first optical system OS1, and 2ωS is the total angle of view of the second optical system OS2.

Note that the values described in [Values corresponding to conditional expressions] are values for the d-line, except for the value of conditional expression (16), which is a value for the s-line.

[Conditional expression corresponding value]
Example Conditional expression 1st 2nd 3rd
(1) -f(gr1n)/f(L) 2.771 1.786 2.871
(2) T(pL)/T(pS) 2.955 2.708 2.765
(3) -f(gr1n)/f(S) 1.562 3.249 1.708
(4) TL(L)/TL(S) 1.202 1.188 1.507
(5) -f(gr1n)/f(gr1p) 0.109 0.089 0.068
(6) f(gr2S)/-f(gr1) 1.368 0.999 1.809
(7) f(gr2L)/-f(gr1) 1.496 3.164 1.750
(8) f(lS)/-f(gr1n) 3.943 1.764 4.191
(9) f(lL)/-f(gr1n) 3.597 2.774 3.864
(10) f(gr2S)/f(S) 2.870 3.631 3.565
(11) f(gr2L)/f(L) 5.567 6.318 5.798
(12) T(pS)/f(S) 2.206 4.338 3.449
(13) T(pL)/f(L) 11.559 6.456 16.030
(14) T(gr1)/f(S) 3.657 3.958 2.876
(15) T(gr1)/f(L) 6.487 2.175 4.835
(16) Nave(s) 1.610 1.620 1.553
(17) f(lS)/f(lL) 1.096 0.636 1.085
(24) 2ωL 92.00 92.00 92.00
(25) 2ωS 92.00 92.00 92.00

Each of the above embodiments shows one specific example of the present invention, and the present invention is not limited thereto.

Next, an optical device including the optical system 1 of this embodiment will be described based on FIG. 14. FIG. 14 is a schematic diagram of an optical device 10 including the optical system 1 of this embodiment.

The optical device 10 includes the optical system 1 according to the first embodiment, an information processing device 2, a first imaging section IS1, and a second imaging section IS2.

The first imaging section IS1 and the second imaging section IS2 each include an imaging element configured from a CCD, CMOS, or the like. In the optical device 10, the optical system 1 appropriately controls each of the incident light reflected by the branching surface BF and the light transmitted by the branching surface BF by a first optical system OS1 and a second optical system OS2. to form an image. The first imaging section IS1 and the second imaging section IS2 are arranged on the image plane I1 of the first optical system OS1 and the image plane I2 of the second optical system OS2, respectively, and output data corresponding to the incident light. The information processing device 2 executes processing using data output by each of the first imaging section IS1 and the second imaging section IS2.

For example, the optical system 1 included in the optical device 10 has a branching surface BF that transmits visible light among the light that enters the optical system 1 from the object and reflects near-infrared light. The first optical system OS1 included in the optical system 1 forms an image of near-infrared light, and the second optical system OS2 forms an image of visible light. The information processing device 2 included in the optical device 10 detects the distance to the target object from the image formed by the first optical system OS1. Further, the information processing device 2 included in the optical device 10 detects the appearance of the object by generating image data from the image obtained by the second optical system OS2.

In this way, the optical device 10 appropriately forms images of the light transmitted by the branching surface BF and the light reflected by the branching surface BF among the incident light, and performs processing using each image. be able to.

Note that, like the optical system 1 of the second embodiment, the optical device 10 includes an optical system in which the first optical system OS1 forms an image of visible light and the second optical system OS2 forms an image of near-infrared light. You can. In this case, the information processing device 2 detects the appearance of the object by generating image data from the image formed by the first optical system OS1, and detects the distance from the image formed by the second optical system OS2 to the object.

Finally, a method for manufacturing the optical system 1 of this embodiment will be outlined based on FIG. 15. FIG. 15 is a flowchart outlining the method for manufacturing the optical system 1 of this embodiment.

The method for manufacturing the optical system 1 of this embodiment shown in FIG. 16 includes the following steps S1 and S2.

Step S1: Prepare a front lens group GR1, a prism P having a branching surface BF, a first rear lens group GR2L, and a second rear lens group GR2S.

Step S2: Each lens group and prism P are arranged so as to satisfy the following conditional expression.
(1) 0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): First optical system focal length of

According to the method for manufacturing an optical system of the present embodiment, it is possible to manufacture an optical system that appropriately images each of the light transmitted by the branching surface and the light reflected by the branching surface among the incident light.

In the optical system of this embodiment, the lens surface may be formed of a spherical surface, a flat surface, or an aspherical surface. It is preferable that the lens surface is spherical or flat because it facilitates lens processing and assembly adjustment and prevents deterioration of optical performance due to errors in processing and assembly adjustment. Further, it is preferable that the lens surface is spherical or flat because there is less deterioration in depiction performance when the image plane shifts.

In the case where the lens surface is an aspherical surface, the aspherical surface may be formed by grinding the glass or by glass molding using a mold having an aspherical shape, and may be formed on the surface of a resin bonded to the surface of the glass. Good too. Further, 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.

Furthermore, an antireflection film having high transmittance over a wide wavelength range may be applied to the lens surface of the lens constituting the optical system of this embodiment. This makes it possible to reduce flare and ghost and achieve optical performance with high contrast.

In the optical system of this embodiment, instead of providing an independent member as the aperture diaphragm, a lens frame or the like may be used instead.

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

1 Optical system OS1 1st optical system OS2 2nd optical system P Prism BF Branching surface GR1 Front lens group GR2L 1st rear lens group GR2S 2nd rear lens group ST1, ST2 Aperture diaphragm I1, I2 Image plane 10 Optical equipment

Claims

In order from the object side: a front lens group, a prism having a branching surface that transmits a part of the incident light and reflects at least another part of the incident light that is different from the part, and the transmitted light. and a first rear lens group into which light having a longer optical path length when passing through the prism among the reflected light enters;
In order from the object side, the front lens group, the prism, and a second rear lens into which the light having a shorter optical path length when passing through the prism among the transmitted light and the reflected light enters. An optical system that satisfies the following conditional expression, comprising: a second optical system having a group;
0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): The first negative lens included in the front lens group. Focal length of optical system
The optical system according to claim 1, which satisfies the following conditional expression.
1.10 < T(pL)/T(pS) < 5.50
however,
T (pL): Length of the prism on the optical axis in the first optical system T (pS): Length of the prism on the optical axis in the second optical system
The optical system according to claim 1 or 2, which satisfies the following conditional expression.
0.50 < -f(gr1n)/f(S) < 4.40
however,
f(S): focal length of the second optical system
The optical system according to any one of claims 1 to 3, which satisfies the following conditional expression.
0.40 < TL(L)/TL(S) < 3.50
however,
TL(L): Optical total length of the first optical system TL(S): Optical total length of the second optical system
The optical system according to any one of claims 1 to 4, which satisfies the following conditional expression.
0.01 < -f(gr1n)/f(gr1p) < 0.21
however,
f(gr1p): Synthetic focal length of the positive lens arranged from the positive lens closest to the object side to the positive lens arranged continuously on the image plane side among the positive lenses included in the front lens group.
6. The optical system according to claim 1, wherein the second rear lens group has an aperture stop and satisfies the following conditional expression.
0.50 < f(gr2S)/(-f(gr1)) < 3.40
however,
f(gr2S): Composite focal length of the lens on the image plane side of the aperture stop in the second rear lens group f(gr1): Composite focal length of the front lens group
7. The optical system according to claim 1, wherein the first rear lens group has an aperture stop and satisfies the following conditional expression.
0.40 < f(gr2L)/(-f(gr1)) < 4.20
however,
f(gr2L): Composite focal length of the lens on the image plane side of the aperture stop in the first rear lens group f(gr1): Composite focal length of the front lens group
The optical system according to any one of claims 1 to 7, which satisfies the following conditional expression.
0.70 < f(lS)/(-f(gr1n)) < 5.90
however,
f(lS): Focal length of the lens closest to the image plane of the second rear lens group
The optical system according to any one of claims 1 to 8, which satisfies the following conditional expression.
1.50 < f(lL)/(-f(gr1n)) < 7.70
however,
f(IL): Focal length of the lens closest to the image plane in the first rear lens group
10. The optical system according to claim 1, wherein the second rear lens group has an aperture stop and satisfies the following conditional expression.
1.60 < f(gr2S)/f(S) < 5.60
however,
f(gr2S): Synthetic focal length of the lens closer to the image plane than the aperture stop in the second rear lens group f(S): Focal length of the second optical system
11. The optical system according to claim 1, wherein the first rear lens group has an aperture stop and satisfies the following conditional expression.
2.30 < f(gr2L)/f(L) < 8.80
however,
f(gr2L): Synthetic focal length of lenses closer to the image plane than the aperture stop in the first rear lens group f(L): Focal length of the first optical system
The optical system according to any one of claims 1 to 11, which satisfies the following conditional expression.
1.20 < T(pS)/f(S) < 6.40
however,
T(pS): Length of the prism on the optical axis in the second optical system f(S): Focal length of the second optical system
The optical system according to any one of claims 1 to 12, which satisfies the following conditional expression.
2.40 < T(pL)/f(L) < 20.50
T(pL): Length of the prism on the optical axis in the first optical system f(L): Focal length of the first optical system
The optical system according to any one of claims 1 to 13, which satisfies the following conditional expression.
1.40 < T(gr1)/f(S) < 6.90
however,
T(gr1): Distance on the optical axis from the lens surface closest to the object side of the front lens group to the lens surface closest to the image plane of the front lens group f(S): Focal length of the second optical system
The optical system according to any one of claims 1 to 14, which satisfies the following conditional expression.
1.00 < T(gr1)/f(L) < 9.80
however,
T(gr1): Distance on the optical axis from the lens surface closest to the object side of the front lens group to the lens surface closest to the image plane of the front lens group f(L): Focal length of the first optical system
The optical system according to any one of claims 1 to 15, which satisfies the following conditional expression.
1.50 < Nave(s) < 1.90
however,
Nave(s): average refractive index for the s-line of the negative lens included in the front lens group
The optical system according to any one of claims 1 to 16, which satisfies the following conditional expression.
0.23 < f(lS)/f(lL) < 1.50
however,
f(lS): Focal length of the lens closest to the image plane in the second rear lens group f(IL): Focal length of the lens closest to the image plane in the first rear lens group
The optical system according to any one of claims 1 to 17, wherein the front lens group has negative refractive power.
The optical system according to claim 1, wherein the front lens group includes one or more positive lenses and one or more negative lenses.
The optical system according to claim 1, wherein the first optical system and the second optical system each have a positive lens closest to the image plane.
The optical system according to any one of claims 1 to 20, which satisfies both of the following conditional expressions.
80.0° < 2ωL
80.0° < 2ωS
however,
2ωL: Full angle of view of the first optical system 2ωS: Full angle of view of the second optical system
Of the transmitted light and the reflected light, one is visible light and the other is near-infrared light, and among the first optical system and the second optical system, from the branching surface to the image plane 22. The optical system according to claim 1, wherein the optical system using the visible light on the side has a cemented lens, and the optical system using the near-infrared light on the image plane side from the branching surface comprises only a single lens. Optical system described.
An optical device comprising the optical system according to any one of claims 1 to 22.
In order from the object side: a front lens group, a prism having a branching surface that transmits a part of the incident light and reflects at least another part of the incident light that is different from the part, and the transmitted light. and a first rear lens group into which light having a longer optical path length when passing through the prism among the reflected light enters;
In order from the object side, the front lens group, the prism, and a second rear lens into which the light having a shorter optical path length when passing through the prism among the transmitted light and the reflected light enters. a second optical system having a group;
A method of manufacturing an optical system comprising: arranging each lens group and the prism so as to satisfy the following conditional expression.
0.80 < -f(gr1n)/f(L) < 4.30
however,
f(gr1n): Synthetic focal length of the negative lens disposed closest to the object side among the negative lenses included in the front lens group and the negative lens disposed continuously on the image plane side f(L): The first negative lens included in the front lens group. Focal length of optical system