Optical system and imaging apparatus

Abstract

To provide an optical system that can prevent a reduction in image quality despite its small size.SOLUTION: An optical system has first and second front groups arranged in a first direction perpendicular to an optical axis direction, and a rear group common to the first and second front groups. A first diaphragm is arranged between the first front group and the rear group, and a second diaphragm is arranged between the second front group and the rear group. A first principal ray passing through the center of the aperture of the first diaphragm and a second principal ray passing through the center of the aperture of the second diaphragm are guided to the intersection of an optical axis of the rear group and an image surface. During infinity focusing, the distance in the first direction between the optical axis and the first principal ray immediately before incident on the rear group, the distance in the first direction between the optical axis and the second principal ray immediately before incident on the rear group, and the focal distance of the rear group, are each appropriately set.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system suitable for imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, and surveillance cameras. [Background technology]

[0002] In recent years, there has been a demand for imaging devices capable of stereoscopic imaging to capture images used in content that provides a sense of realism, such as virtual reality. In particular, there is a demand for stereoscopic imaging devices that can capture images from two viewpoints with parallax similar to that of humans.

[0003] Patent Document 1 discloses a configuration that includes a front group and a common rear group arranged in parallel, with an aperture corresponding to the front group located on the rear group side, making it possible to acquire parallax images in a single shot. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6280803 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the configuration of Patent Document 1 does not take into consideration the influence of crosstalk between photoelectric conversion units based on the angle of light incident on the image sensor, resulting in a mixture of signals from the respective parallax images and a decrease in image quality. On the other hand, if a configuration that suppresses the influence of crosstalk is adopted, the optical system will become larger and more complicated.

[0006] An object of the present invention is to provide an optical system that is compact yet capable of suppressing degradation in image quality. [Means for solving the problem]

[0007] An optical system according to one aspect of the present invention has first and second front groups arranged in a first direction perpendicular to the optical axis direction, and a rear group common to the first and second front groups, wherein a first diaphragm is disposed between the first front group and the rear group, and a second diaphragm is disposed between the second front group and the rear group, a first chief ray passing through the center of the aperture of the first diaphragm and a second chief ray passing through the center of the aperture of the second diaphragm are guided to an intersection of the optical axis of the rear group and an image plane, and when focusing at infinity, let Sh1 be the distance in the first direction between the first chief ray and the optical axis immediately before entering the rear group, Sh2 be the distance in the first direction between the second chief ray and the optical axis immediately before entering the rear group, and fb be the focal length of the rear group. 0.06≦|Sh1 / fb|≦0.50 0.06≦|Sh2 / fb|≦0.50 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an optical system that is compact yet capable of suppressing degradation in image quality. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an optical system according to an embodiment of the present invention. [Figure 2] FIG. 1 illustrates light rays passing through an optical system. [Figure 3] FIG. 2 is a diagram showing a part of an optical system and an image sensor arranged on an image plane. [Figure 4] 10 is a diagram illustrating the relationship between the output signal of a photoelectric conversion unit and the angle of incidence. FIG. [Figure 5] FIG. 10 is a diagram showing a modified example of the optical system 1. [Figure 6] FIG. 1 is a diagram illustrating an optical system according to a first embodiment. [Figure 7] FIG. 1 is a diagram illustrating a part of an optical system according to a first embodiment. [Figure 8] FIG. 10 is a diagram illustrating a part of an optical system according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing a part of an optical system according to a third embodiment. [Figure 10] 10A and 10B are diagrams illustrating a case where the image plane position of the optical system has changed. [Figure 11] FIG. 1 is a diagram showing an imaging device including an optical system. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0011] FIG. 1 is a diagram showing an optical system 1 according to an embodiment of the present invention. The optical system 1 includes, arranged in order from the object side to the image side, a front group LEF, a stop, and a rear group LEB. The front group LEF includes a first front group LER and a second front group LEL, each including one or more optical elements. The first front group LER and the second front group LEL are arranged in a direction (first direction) perpendicular to a direction (optical axis direction) parallel to the optical axis OAB of the rear group LEB. In this embodiment, the first front group LER and the second front group LEL are the same optical system. The stop includes a first stop APR and a second stop APL. The first stop APR and the second stop APL are arranged adjacent to the object side of the rear group LEB. The rear group LEB includes one or more optical elements. The optical axis OAR of the first front group LER, the optical axis OAL of the second front group LEL, and the optical axis OAB of the rear group LEB are defined as axes passing through the surface vertices of the optical elements. When some optical elements with refractive power are decentered to effectively correct aberrations, the common optical axis that comprises the largest number of optical elements is set as the optical axis of each group. IM denotes the image plane of optical system 1.

[0012] It is preferable that the rear group LEB has positive refractive power. This configuration is preferable because it increases the angle of each ray passing through the first front group LER and the second front group LEL and incident on the image sensor, thereby suppressing the effects of crosstalk. While the rear group LEB may have negative refractive power, it is preferable that it have positive refractive power for the reasons mentioned above.

[0013] Furthermore, it is preferable that the lenses closest to the object side of the first front group LER and the second front group LEL are negative lenses. This configuration is preferable because it allows for a reduction in the size of the optical system while enabling stereoscopic photography.

[0014] Furthermore, it is preferable that the lens closest to the image side in the optical system 1 is a positive lens. This is preferable because the angle of light rays incident on the periphery of the image sensor can be reduced and the effects of crosstalk can be suppressed.

[0015] Furthermore, it is preferable that the optical system 1 has an optical element that moves during focusing. The optical element may be provided in either the front group LEF or the rear group LEB. In this case, the imaging device body to which the optical system 1 is attached is provided with a focus mechanism that moves the optical element during focusing.

[0016] FIG. 2 is a diagram showing light rays passing through the optical system 1. The first light ray RYR is the chief ray (first chief ray) of the light that passes through the first front group LER and the rear group LEB and is focused on the image plane IM, passing through the center of the aperture of the diaphragm. The second light ray RYL is the chief ray (second chief ray) of the light that passes through the second front group LEL and the rear group LEB and is focused on the image plane IM, passing through the center of the aperture of the diaphragm. When focusing at infinity, the first light ray RYR passes through a position separated by a distance (width) Sh1 from the optical axis OAB in a direction perpendicular to the optical axis OAB just before entering the rear group LEB. When focusing at infinity, the second light ray RYL passes through a position separated by a distance (width) Sh2 from the optical axis OAB in a direction perpendicular to the optical axis OAB just before entering the rear group LEB. The first light ray RYR immediately before entering the rear group LEB, the second light ray RYL immediately before entering the rear group LEB, and the optical axis OAB are parallel to each other and non-coaxial. The first light ray RYR and the second light ray RYL are guided to the intersection of the image plane IM and the optical axis OAB. This makes it possible to acquire parallax images regardless of the position of the object plane of the optical system 1.

[0017] FIG. 3 is a diagram showing a portion of the optical system 1 and an image sensor SN arranged on an image plane IM. The image sensor SN includes a plurality of pixels IP. Each pixel IP includes a microlens ML, a first photoelectric conversion unit PD1, and a second photoelectric conversion unit PD2. It is desirable that the arrangement direction of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2 is the same direction (parallel) as the arrangement direction of the first front group LER and the second front group LEL. Note that FIG. 3 shows only the first light ray RYR and the second light ray RYL that pass through the centers of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2, and omits the other light rays.

[0018] The optical system 1 focuses the first light ray RYR and the second light ray RYL onto the same (common) microlens ML. At this time, the first light ray RYR and the second light ray RYL pass through different pupils and are therefore incident on the microlens ML at different angles of incidence. Specifically, one light ray is incident on the microlens ML from above and the other light ray is incident on the microlens ML from below with respect to the normal line indicated by the dashed dotted line to the imaging surface of the image sensor SN. That is, in this embodiment, the signs of the angles of incidence of the first light ray RYR and the second light ray RYL on the microlens ML are different from each other. The absolute values ​​of the angles of incidence of the first light ray RYR and the second light ray RYL on the microlens ML may be different. Note that the normal line may be a cross section including the optical axis of the microlens ML.

[0019] The microlens ML focuses (incident) the first light ray RYR that has passed through the first aperture APR on the first photoelectric conversion unit PD1. The microlens ML also focuses (incident) the second light ray RYL that has passed through the second aperture APL on the second photoelectric conversion unit PD2. That is, the optical system 1 guides the first light ray RYR that has passed through the microlens ML to the first photoelectric conversion unit PD1, and guides the second light ray RYL that has passed through the microlens ML to the second photoelectric conversion unit PD2. Therefore, by separating the signals from the photoelectric conversion units PD1 and PD2, it is possible to separate signals based on light rays that have passed through the first front group LER and signals based on light rays that have passed through the second front group LEL.

[0020] In the optical system 1, a first light ray RYR guided by the first front group LER and a second light ray RYL guided by the second front group LEL pass through a common rear group LEB and are focused onto a single image sensor SN on the image plane IM. This allows the first light ray RYR and the second light ray RYL to be guided to the image sensor SN by the common rear group LEB, thereby simplifying the optical system 1.

[0021] The optical axes of the microlenses ML located in the peripheral portion of the image sensor SN may be offset relative to the intermediate portion between the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2. The optical axes of the microlenses ML may be decentered parallel to the center relative to the intermediate portion between the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2. The amount of decentering may be different for each region of the image sensor SN.

[0022] Here, a light ray that is incident on the center of the microlens ML of any pixel IP and guided between the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2 of the pixel IP is defined as a reference light ray for the pixel IP. The reference light ray may be different for each position of the pixel IP in the image sensor SN. In this case, it is preferable that the angle of incidence of the reference light ray that is incident on the microlens ML of the pixel IP located on the periphery of the image sensor SN is larger (inclined) than the angle of incidence of the reference light ray that is incident on the microlens ML of the pixel IP located on the periphery of the image sensor SN. Furthermore, the reference light ray that is incident on the microlens ML located on the center of the image sensor SN is parallel to the normal to the imaging surface of the image sensor SN.

[0023] Here, θ1 is the angle of incidence of the first light ray RYR on the microlens ML. The angle of incidence θ1 is determined by the focal length of the rear group LEB and the width Sh1 between the first principal ray and the optical axis OAB. In other words, the shorter the focal length of the rear group LEB or the wider the width Sh1, the larger the angle of incidence θ1.

[0024] FIG. 4 is a diagram showing the distribution (signal intensity distribution) of signal intensity obtained at each photoelectric conversion unit with respect to the angle of incidence of a light ray on the image sensor SN. In FIG. 4, the vertical axis represents signal intensity corresponding to the light receiving sensitivity of the first photoelectric conversion unit PD1 or the second photoelectric conversion unit PD2. The horizontal axis represents the angle of incidence of the first light ray RYR and the second light ray RYL on the microlens ML. The values ​​on the horizontal axis are normalized based on the intersection of the signal intensity distributions of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2. FIG. 4 shows signal intensities when the incident angle θ1 is θ11, θ12, and θ13. Note that normalization may also be performed by associating the intersection of the signal intensity distributions of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2 with the incident angle of a reference light ray on an arbitrary pixel.

[0025] In FIG. 4, the first photoelectric conversion unit PD1, which photoelectrically converts the first light ray RYR, has signal intensity even at the incident angle on the photoelectric conversion unit PD2 side due to the influence of crosstalk occurring between adjacent photoelectric conversion units. Note that crosstalk also occurs with the second photoelectric conversion unit PD2, similar to the first photoelectric conversion unit PD1. The amount of crosstalk occurring in the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2 varies depending on the incident angle with respect to the image sensor SN (or microlens ML). Furthermore, the influence of crosstalk increases when the incident angle approaches the intersection of the signal intensity distributions of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2, i.e., when the incident angle θ1 becomes θ11. Therefore, the influence of crosstalk can be suppressed by appropriately adjusting the incident angle with respect to the microlens ML. Note that the amount of crosstalk may be expressed as the ratio of the signal intensity of the first photoelectric conversion unit PD1 to the signal intensity of the second photoelectric conversion unit PD2.

[0026] Crosstalk includes at least one of optical crosstalk caused by stray light resulting from reflection or scattering occurring in, for example, microlenses ML or wiring layers, and electrical crosstalk caused by charge moving to other adjacent photoelectric conversion units.

[0027] In this embodiment, the optical system 1 satisfies the following conditional expressions (1) and (2) using the widths Sh1 and Sh2 and the focal length fb of the rear group LEB.

[0028] 0.06≦|Sh1 / fb|≦0.50 (1) 0.06≦|Sh2 / fb|≦0.50 (2) By satisfying conditional expressions (1) and (2), the angles of incidence of the first light ray RYR and the second light ray RYL incident on the microlens ML of the image sensor SN can be appropriately set. Exceeding the upper limits of conditional expressions (1) and (2) increases the effective diameter of the rear group LEB (the diameter on the lens surface of the light ray passing through the rear group LEB at the position farthest from the optical axis OAB), resulting in an increase in the size of the optical system 1 and difficulty in effectively correcting various aberrations. Falling below the lower limits of conditional expressions (1) and (2), the effects of crosstalk increase, reducing the signal-to-noise ratio (SN ratio) of each signal acquired by the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2, potentially resulting in a degradation of image quality.

[0029] It is preferable that the numerical ranges of the conditional expressions (1) and (2) be within the ranges of the following conditional expressions (1a) and (2a).

[0030] 0.07≦|Sh1 / fb|≦0.45 (1a) 0.07≦|Sh2 / fb|≦0.45 (2a) It is more preferable that the numerical ranges of the conditional expressions (1) and (2) be within the ranges of the following conditional expressions (1b) and (2b).

[0031] 0.08≦|Sh1 / fb|≦0.39 (1b) 0.08≦|Sh2 / fb|≦0.39 (2b) Furthermore, when the focal length of the optical system 1 (configuration from the first front unit LER to the rear unit LEB) is f_total, it is preferable that the optical system 1 satisfy the following conditional expression (3):

[0032] 0.5≦(|Sh1|+|Sh2|) / f_total)≦7.0 (3) If the upper limit of conditional expression (3) is exceeded, the optical system 1 becomes large, and the optical path length must be extended. This makes it difficult to correct aberrations, and requires an increase in the number of optical elements. If the lower limit of conditional expression (3) is exceeded, it is not preferable because sufficient parallax images for stereoscopic photography cannot be obtained.

[0033] It is preferable that the numerical range of conditional expression (3) be set to the range of the following conditional expression (3a).

[0034] 0.6≦(|Sh1|+|Sh2|) / f_total)≦6.8 (3a) It is more preferable that the numerical range of conditional expression (3) be set to the range of the following conditional expression (3b).

[0035] 0.7≦(|Sh1|+|Sh2|) / f_total)≦6.5 (3b) Here, the signal intensities of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2 are denoted as PD1S and PD2S, respectively, and the amounts of crosstalk occurring in the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2 are denoted as CT1 and CT2. Furthermore, when the corrected signal intensities (corrected signal intensities) corresponding to the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2, respectively, are denoted as PD1S' and PD2S', the respective relationships can be expressed by the following equations (4a) and (4b).

[0036] PD1S´=PD1S-PD2S×CT1 (4a) PD2S´=PD2S-PD1S×CT2 (4b) In this embodiment, by using equations (4a) and (4b), a correction signal can be obtained that suppresses the influence of crosstalk occurring between the photoelectric conversion units based on the signal strength and crosstalk amount of the first photoelectric conversion unit PD1 and the second photoelectric conversion unit PD2.

[0037] FIG. 5 shows a modified example of the optical system 1. The optical system 1 has first reflecting surfaces R1R and R1L arranged on the optical path from the first front group LER to the rear group LEB. The optical system 1 also has second reflecting surfaces R2R and R2L arranged on the optical path from the second front group LEL to the rear group LEB. This configuration allows the distance between the optical axes OAR and OAL of the first front group LER and the second front group LEL to be increased, thereby increasing the base length. This allows for a larger parallax for obtaining a stereoscopic image. The reflecting surfaces R1R and R1L may be configured to perform total reflection, such as prisms. While the optical path in FIG. 5 is bent vertically relative to the page, it may also be bent in the depth direction.

[0038] Fig. 6 is a diagram showing an optical system of Example 1. Fig. 7 is a diagram showing a part of the optical system of Example 1. Fig. 8 is a diagram showing a part of the optical system of Example 2. Fig. 9 is a diagram showing a part of the optical system of Example 3.

[0039] As shown in Fig. 6, the optical system of Example 1 has an optical group 101 including a first front group and a rear group, and an optical group 102 including a second front group and a rear group. The optical systems of Examples 2 and 3 also have two optical groups. Figs. 7 to 9 respectively show optical groups 101, 201, and 301 including the first front group.

[0040] 7, optical group 101 includes a first front group F1, reflecting surfaces R11 and R12 for bending the optical path, an aperture stop AP11, and a rear group B1. IM1 is the image plane.

[0041] As shown in FIG. 8, the optical group 201 includes a first front group F2, reflecting surfaces R21 and R22 for bending the optical path, an aperture stop AP21, and a rear group B2. IM2 is an image plane. IF1 is an intermediate image formed by the first front group F2 in the optical path. In this embodiment, the intermediate image IF1 is formed on the object side of the rear group LEB.

[0042] 9, the optical group 301 includes a first front group F3, reflecting surfaces R31 and R32 for bending the optical path, an aperture stop AP31, and a rear group B3. IM3 is the image plane.

[0043] Numerical Examples 1 to 3 corresponding to Examples 1 to 3, respectively, are shown below. In each numerical example, R represents the radius of curvature of each optical surface. The radius of curvature R is positive when it is convex toward the intermediate image, and negative when it is concave. D represents the distance between the m-th surface and the (m+1)-th surface. The surface distance D is positive when it is directed toward the reduction-side conjugate surface. Furthermore, m is the surface number counted from the light incident side. Furthermore, Nd represents the refractive index of each optical member with respect to the d-line, and vd represents the Abbe number of the optical member. Note that the Abbe number vd of a certain material is given by the following when the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines are Nd, NF, and NC, respectively: νd=(Nd-1) / (NF-NC) It is expressed as:

[0044] Although the optical surfaces in each of Numerical Examples 1 to 3 are configured with rotationally symmetric spherical surfaces, rotationally symmetric aspherical surfaces, anamorphic surfaces, and free-form surfaces may be used as needed. Also, a cover glass, dustproof glass, or the like may be placed on the optical path. Furthermore, a decentered system or reflection using a reflecting surface may be used depending on the device layout.

[0045] (Numerical Example 1) JPEG2025138350000002.jpg145145

[0046] (Numerical Example 2) JPEG2025138350000003.jpg178139

[0047] (Numerical Example 3) JPEG2025138350000004.jpg161148

[0048] The values ​​of the conditional expressions (1), (2), and (3) in the optical groups 101, 201, and 301 in Numerical Examples 1 to 3 are shown in Table 1 below.

[0049] [Table 1]

[0050] FIG. 10 illustrates a case where the image plane position of the optical system 1 changes due to focusing or the like. When the object plane is focused from a distant position to a nearby position, the angle of the light rays incident on the image plane IM changes from θF to θN. In other words, the angle of incidence changes as the distance from the rear principal plane of the optical system 1 to the image plane IM changes. Therefore, it is desirable that equations (4a) and (4b) take into account the change in the distance from the rear principal plane to the image plane IM due to focusing. For example, the change in the distance from the object plane or the distance from the rear principal plane to the image plane IM that occurs when moving at least one optical element constituting the optical system 1 can be recorded in advance, and the change in the angle of incidence of the light rays incident on the image plane IM can be estimated based on the actual movement amount. Therefore, the amount of crosstalk can be changed depending on the change in the angle of incidence of the light rays incident on the image plane IM that occurs due to focusing or the like. Note that while FIG. 10 illustrates focusing being performed by moving all of the lens groups, focusing may also be performed by moving only some of the optical elements.

[0051] FIG. 11 is a diagram showing an imaging device (digital still camera) 400 using the optical system 1 of this embodiment as an imaging optical system 420. The imaging device 400 includes a camera 430 equipped with an imaging unit 440 including an image sensor SN, and a lens device 410 equipped with the imaging optical system 420. The lens device 410 may be configured integrally with the camera 430, or may be configured detachably. The imaging device 400 may also include a calculation unit (correction unit) that corrects signals from each photoelectric conversion unit using equations (4a) and (4b) and calculates (acquires) the corrected signal intensity, and a storage unit that stores a table of crosstalk amounts for each focus position. Note that only one optical system is shown in FIG. 11 because two optical systems are arranged side by side in the depth direction. The imaging device 400 is configured with an imaging optical system 420 including a common rear group appropriately arranged, enabling stereoscopic imaging with reduced image quality degradation despite its compact size. The optical system 1 is not limited to digital still cameras, but can also be applied to various imaging devices such as broadcast cameras, cameras using silver halide film, and surveillance cameras.

[0052] The disclosure of this embodiment includes the following configuration. (Configuration 1) An optical system having first and second front groups arranged in a first direction perpendicular to an optical axis direction, and a rear group common to the first and second front groups, a first diaphragm is disposed between the first front group and the rear group, and a second diaphragm is disposed between the second front group and the rear group; a first chief ray passing through the center of the aperture of the first aperture and a second chief ray passing through the center of the aperture of the second aperture are guided to an intersection point between the optical axis of the rear group and an image plane, When focusing at infinity, let Sh1 be the distance in the first direction between the first principal ray immediately before entering the rear group and the optical axis, let Sh2 be the distance in the first direction between the second principal ray immediately before entering the rear group and the optical axis, and let fb be the focal length of the rear group. 0.06≦|Sh1 / fb|≦0.50 0.06≦|Sh2 / fb|≦0.50 An optical system characterized by satisfying the following conditional expression: (Configuration 2) The optical system described in configuration 1, wherein the first chief ray immediately before entering the rear group, the second chief ray immediately before entering the rear group, and the optical axis are parallel to each other and non-coaxial. (Configuration 3) 3. The optical system according to configuration 1 or 2, wherein the rear group has positive refractive power. (Configuration 4) 4. The optical system according to any one of configurations 1 to 3, wherein the first and second front groups are the same optical system. (Configuration 5) 5. The optical system according to any one of configurations 1 to 4, wherein the first and second stops are disposed adjacent to each other on the object side of the rear group. (Configuration 6) 6. The optical system according to any one of configurations 1 to 5, wherein an intermediate image is formed in the optical path of the optical system. (Configuration 7) 7. The optical system according to any one of configurations 1 to 6, wherein an intermediate image is formed on the object side of the rear group. (Configuration 8) 8. The optical system according to any one of configurations 1 to 7, wherein the lenses of the first and second front groups closest to the object side are negative lenses. (Configuration 9) 9. The optical system according to any one of configurations 1 to 8, wherein the lens closest to the image side of the optical system is a positive lens. (Configuration 10) 10. The optical system according to any one of configurations 1 to 9, further comprising an optical element that moves during focusing. (Configuration 11) When the focal length of the optical system is f_total, 0.5≦(|Sh1|+|Sh2|) / f_total)≦7.0 11. The optical system according to any one of configurations 1 to 10, wherein the following condition is satisfied: (Configuration 12) An imaging device to which the optical system according to any one of configurations 1 to 11 can be detachably attached, and an image sensor including first and second photoelectric conversion units that photoelectrically convert images formed by light that has passed through the first and second apertures, respectively. (Configuration 13) 13. The imaging device according to configuration 12, wherein the direction in which the first and second photoelectric conversion units are arranged and the direction in which the first and second front groups are arranged are parallel to each other. (Configuration 14) The imaging device described in Configuration 12 or 13, further comprising a correction unit that corrects signals from the first and second photoelectric conversion units based on the distance from a first chief ray immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, the distance from a second chief ray immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, and the focal length of the rear group when focusing at infinity. (Configuration 15) 15. The imaging device according to any one of configurations 12 to 14, further comprising a focus mechanism that moves at least one optical element included in the optical system during focusing. (Configuration 16) The imaging device described in Configuration 15, further comprising a correction unit that corrects signals from the first and second photoelectric conversion units based on a distance from a first chief ray of light immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, a distance from a second chief ray of light immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, a focal length of the rear group, and an amount of change in a distance from an image plane to a rear principal plane due to the focus mechanism, when focusing at infinity. (Configuration 17) When the signal intensities of the first and second photoelectric conversion units are PD1S and PD2S, the amounts of crosstalk occurring in the first and second photoelectric conversion units are CT1 and CT2, and the corrected signal intensities corresponding to the first and second photoelectric conversion units are PD1S' and PD2S', respectively, the correction unit: PD1S´=PD1S-PD2S×CT1 PD2S´=PD2S-PD1S×CT2 17. The imaging device according to configuration 14 or 16, wherein the signals from the first and second photoelectric conversion units are corrected using the following formula:

[0053] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0054] 1 Optical system APL 2nd aperture APR First Aperture LEB rear group LEF front group LEL Second front group LER 1st front group

Claims

1. An optical system having first and second front groups arranged in a first direction perpendicular to an optical axis direction, and a rear group common to the first and second front groups, a first diaphragm is disposed between the first front group and the rear group, and a second diaphragm is disposed between the second front group and the rear group; a first chief ray passing through the center of the aperture of the first aperture and a second chief ray passing through the center of the aperture of the second aperture are guided to an intersection point between the optical axis of the rear group and an image plane, When focusing at infinity, let Sh1 be the distance in the first direction between the first principal ray immediately before entering the rear group and the optical axis, let Sh2 be the distance in the first direction between the second principal ray immediately before entering the rear group and the optical axis, and let fb be the focal length of the rear group. 0.06≦|Sh1 / fb|≦0.50 0.06≦|Sh2 / fb|≦0.50 An optical system characterized by satisfying the following conditional expression:

2. 2. The optical system according to claim 1, wherein the first chief ray immediately before entering the rear group, the second chief ray immediately before entering the rear group, and the optical axis are parallel to each other and non-coaxial.

3. 3. The optical system according to claim 1, wherein the rear group has positive refractive power.

4. 3. The optical system according to claim 1, wherein the first and second front groups are the same optical system.

5. 3. The optical system according to claim 1, wherein the first and second stops are arranged adjacent to each other on the object side of the rear group.

6. 3. The optical system according to claim 1, wherein an intermediate image is formed in the optical path of the optical system.

7. 3. The optical system according to claim 1, wherein an intermediate image is formed on the object side of the rear group.

8. 3. The optical system according to claim 1, wherein the lens element closest to the object side in each of the first and second front groups is a negative lens element.

9. 3. The optical system according to claim 1, wherein the lens closest to the image side of the optical system is a positive lens.

10. 3. The optical system according to claim 1, further comprising an optical element that moves during focusing.

11. When the focal length of the optical system is f_total, 0.5≦(|Sh1|+|Sh2|) / f_total)≦7.0 3. The optical system according to claim 1, wherein the following condition is satisfied:

12. 3. An imaging device to which the optical system according to claim 1 or 2 can be detachably attached, an image sensor including first and second photoelectric conversion units that photoelectrically convert images formed by light that has passed through the first and second apertures, respectively.

13. 13. The image pickup apparatus according to claim 12, wherein the direction in which the first and second photoelectric conversion units are arranged and the direction in which the first and second front groups are arranged are parallel to each other.

14. 13. The image pickup apparatus according to claim 12, further comprising a correction unit that corrects signals from the first and second photoelectric conversion units based on a distance from a first chief ray immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, a distance from a second chief ray immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, and a focal length of the rear group, when focusing at infinity.

15. 13. The imaging apparatus according to claim 12, further comprising a focus mechanism that moves at least one optical element included in the optical system during focusing.

16. 16. The image pickup apparatus according to claim 15, further comprising a correction unit that corrects signals from the first and second photoelectric conversion units based on a distance from a first chief ray of light immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, a distance from a second chief ray of light immediately before entering the rear group to the optical axis in a direction perpendicular to the optical axis, a focal length of the rear group, and an amount of change in a distance from an image plane to a rear principal plane caused by the focus mechanism, during focusing at infinity.

17. When the signal intensities of the first and second photoelectric conversion units are PD1S and PD2S, the amounts of crosstalk occurring in the first and second photoelectric conversion units are CT1 and CT2, and the corrected signal intensities corresponding to the first and second photoelectric conversion units are PD1S' and PD2S', respectively, the correction unit: PD1S'=PD1S-PD2S×CT1 PD2S'=PD2S-PD1S×CT2 15. The imaging device according to claim 14, wherein the signals from the first and second photoelectric conversion units are corrected using the following formula:

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