Stereoscopic optical system and image pickup apparatus

Abstract

The invention discloses a stereoscopic optical system and an image pickup apparatus. A stereoscopic optical system includes two optical systems arranged in parallel. Each of the two optical systems includes an aperture stop and at least two positive lenses disposed on an image side of the aperture stop. A predetermined inequality is satisfied.

Description

Technical Field

[0001] The present disclosure relates to a stereoscopic optical system for stereoscopic imaging and an image pickup device having the stereoscopic optical system. Background Art

[0002] In a stereoscopic optical system including two optical systems arranged side by side with the distance between their optical axes as the baseline length, as the baseline length changes, the three-dimensional effect of the image to be stereoscopically viewed changes. Japanese Patent Laid-Open No. 2020-008629 discloses a stereoscopic optical system that accommodates two image circles formed by two optical systems within the imaging surface of a single image sensor.

[0003] The stereoscopic optical system disclosed in Japanese Patent Laid-Open No. 2020-008629 accommodates two image circles within a single imaging surface by using two reflecting surfaces that bend the optical path in each of the two optical systems and ensures a sufficient baseline length. Summary of the Invention

[0004] A stereoscopic optical system according to one aspect of the present disclosure includes two optical systems arranged side by side. Each of the two optical systems includes an aperture stop and at least two positive lenses disposed on the image side of the aperture stop. The following inequality is satisfied:

[0005] 1.8 ≤ D / (f tanω) ≤ 5.5

[0006] where D is the distance between the optical axes of the two optical systems, f is the focal length of each of the two optical systems, and ω is the maximum half field angle of each of the two optical systems. An image pickup device having the above stereoscopic optical system also constitutes another aspect of the present disclosure.

[0007] More features of various embodiments of the present disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. Brief Description of the Drawings

[0008] Figure 1 is a cross-sectional view of one of the optical systems in the stereoscopic optical system according to Example 1.

[0009] Figure 2 is an aberration diagram of one of the optical systems according to Example 1.

[0010] Figure 3 is a cross-sectional view of one of the optical systems in the stereoscopic optical system according to Example 2.

[0011] Figure 4 is an aberration diagram of one of the optical systems according to Example 2.

[0012] Figure 5 It is a cross-sectional view of an optical system in the three-dimensional optical system according to Example 3.

[0013] Figure 6 It is an aberration diagram of an optical system according to Example 3.

[0014] Figure 7 It is a cross-sectional view of an optical system in the three-dimensional optical system according to Example 4.

[0015] Figure 8 It is an aberration diagram of an optical system according to Example 4.

[0016] Figure 9 It is a cross-sectional view of an optical system in the three-dimensional optical system according to Example 5.

[0017] Figure 10 It is an aberration diagram of an optical system according to Example 5.

[0018] Figure 11 It is a top view of the three-dimensional optical system according to each example.

[0019] Figure 12 It illustrates two image circles formed by the three-dimensional optical system according to Example 1.

[0020] Figure 13 It is a schematic diagram of an image pickup device having a three-dimensional optical system according to any one of the examples. Detailed Description

[0021] Now, with reference to the accompanying drawings, a description of the examples according to the present disclosure will be given.

[0022] Before specifically describing Examples 1 to 5, a description of matters common to each example will be given. Figure 11 It illustrates a three-dimensional optical system according to Example 1 as a representative example when viewed from above. The three-dimensional optical system according to each example includes a right optical system OSR and a left optical system OSL as two coaxial optical systems arranged side by side. The right optical system OSR and the left optical system OSL are arranged such that their optical axes extend parallel to each other with a baseline length D therebetween, and the baseline length D is the distance between their optical axes. Each of the right optical system OSR and the left optical system OSL includes an aperture stop (iris diaphragm) SP. IP represents the image plane. The imaging surface (light receiving surface) of the image sensor or the film surface (photosensitive surface) of the silver film is disposed on the image plane IP.

[0023] Figure 1 , Figure 3 , Figure 5 , Figure 7 and Figure 9Cross-sections of one of the right optical system OSR and the left optical system OSL in the stereo optical systems according to Examples 1 to 5 in a focus state for an object at infinity (hereinafter referred to as "in a focus state at infinity") are shown respectively.

[0024] Each optical system (OSR and OSL) includes, in order from the object side to the image side, a front lens unit F, an aperture stop SP, and a rear lens unit R. The rear lens unit R includes at least two positive lenses (a first positive lens Rp1 and a second positive lens Rp2).

[0025] Figure 12 An image circle ICR formed by the right optical system OSR on an image plane (e.g., an imaging surface of a single image sensor) IP and an image circle ICL formed by the left optical system OSL on the same image plane IP are shown. The right image circle ICR and the left image circle ICL are formed side by side on the image plane IP. Thus, two captured images (a pair of parallax images) having parallax and viewable stereoscopically can be obtained by an image pickup device such as a digital camera having a single image sensor.

[0026] In each example, the negative lens Fn closest to the object in the front lens unit F can achieve a wide-angle optical system. In each optical system, the second positive lens Rp2 closest to the image plane in the rear lens unit R and the negative lenses (a first negative lens Rn1 and a second negative lens Rn2) disposed on the object side of the second positive lens Rp2 can reduce the incident angle of off-axis light on the image plane (the imaging surface of the image sensor) IP. This configuration can reduce color shading that appears in the image sensor.

[0027] In each optical system, the first positive lens Rp1 having a high refractive index disposed on the object side of the second positive lens Rp2 closest to the image plane in the rear lens unit R can effectively converge light while satisfactorily correcting spherical aberration that appears in the first negative lens Rn1. Thus, both a large aperture and a compact optical system can be achieved.

[0028] In each optical system according to each example, the optical system moves entirely or partially on the optical axis during focusing. In Figure 1 、 Figure 3 、 Figure 5 、 Figure 7 and Figure 9 ,the arrows indicate the moving directions of the lenses and the aperture stop SP that move during focusing from an object at infinity to an object at a close distance.

[0029] Each optical system in each example can satisfy the following inequality (1):

[0030] 1.8 ≤ D / (f tan ω) ≤ 5.5 (1)

[0031] Where D is the baseline length, f is the focal length of the optical system, and ω is the maximum semi-field angle of the optical system.

[0032] Inequality (1) defines an appropriate relationship between the baseline length and the size of the image sensor to obtain a good three-dimensional effect from two captured images while improving the image quality of each captured image. When the baseline length D increases such that D / (f tanω) becomes higher than the upper limit of inequality (1), the size of the image circle on the image sensor becomes smaller, resulting in a decrease in the image quality of the captured image. When the baseline length D decreases such that D / (f tanω) becomes lower than the lower limit of inequality (1), the three-dimensional effect obtained from the two captured images decreases, the two image circles overlap each other on the image sensor, and an appropriate parallax image cannot be obtained.

[0033] Inequality (1) can be replaced by the following inequality (1a):

[0034] 1.9 ≤ D / (f tanω) ≤ 5.0 (1a)

[0035] Inequality (1) can be replaced by the following inequality (1b):

[0036] 2.0 ≤ D / (f tanω) ≤ 4.5 (1b)

[0037] The above configuration and inequality (1) can achieve a stereo optical system with a large aperture, high optical performance, reduced size and baseline length, and can provide good stereoscopic imaging.

[0038] Each optical system according to each example can satisfy at least one of the following inequalities (2) to (12). In these expressions, fF is the focal length of the front lens unit F deployed on the object side of the aperture stop SP, and fR is the focal length of the rear lens unit R deployed on the image side of the aperture stop SP. fRn1 is the focal length of the first negative lens Rn1 having the strongest refractive power among at least one negative lens included in the rear lens unit R. In the rear lens unit R, fRp2 is the focal length of the second positive lens Rp2 having the strongest refractive power among at least one positive lens deployed on the image side of the first negative lens Rn1. In the rear lens unit R, fRp1 is the focal length of the first positive lens Rp1 having the strongest refractive power among at least one positive lens deployed on the object side of the second lens Rp2.

[0039] fFp is the focal length of the positive lens Fp having the strongest refractive power among at least one positive lens included in the front lens unit F. In the front lens unit F, fFn is the focal length of the negative lens Fn having the strongest refractive power deployed on the object side of the positive lens Fp.

[0040] R1 is the radius of curvature of the image-side surface of the first negative lens Rn1, and R2 is the radius of curvature of the object-side surface of the second negative lens Rn2 that is adjacent to the first negative lens Rn1 via an air gap and is disposed on the image side of the first negative lens Rn1. ndRp1 is the refractive index for the d-line of the material of the first positive lens Rp1. L is the length on the optical axis from the surface closest to the object (front surface) of the optical system to the image plane IP in the focused state at infinity (total optical length), sk is the back focal length of the optical system in the focused state at infinity, and t1 is the distance on the optical axis from the front surface of the optical system to the entrance pupil position.

[0041] -1.0 ≤ f / fF ≤ 1.4 (2)

[0042] -0.9 ≤ fR / fF ≤ 2.4 (3)

[0043] -6.0 ≤ fR / fRn1 ≤ -1.4 (4)

[0044] -3.2 ≤ fRp2 / fRn1 ≤ -1.0 (5)

[0045] 0.4 ≤ fRp2 / fRp1 ≤ 4.5 (6)

[0046] -2.0 ≤ fFn / fFp ≤ -0.1 (7)

[0047] -0.8 ≤ (R2+R1) / (R2-R1) ≤ 0.3 (8)

[0048] 1.6 ≤ ndRp1 ≤ 2.2 (9)

[0049] 2.0 ≤ L / f ≤ 5.5 (10)

[0050] 0.3 ≤ sk / f ≤ 0.9 (11)

[0051] 0.2 ≤ t1 / f ≤ 1.3 (12)

[0052] Inequality (2) defines an appropriate relationship between the focal length of the optical system and the focal length of the front lens unit F by ensuring the back focal length of the optical system and minimizing the coma aberration and distortion in the optical system. When the positive refractive power of the front lens unit F increases and f / fF becomes higher than the upper limit of inequality (2), the principal point position of the optical system moves toward the object side, and it becomes difficult to ensure the back focal length. When the negative refractive power of the front lens unit F increases and f / fF becomes lower than the lower limit of inequality (2), it becomes difficult to correct the coma aberration and distortion generated in the rear lens unit R.

[0053] Inequality (3) defines an appropriate relationship between the focal length of the rear lens unit R and the focal length of the front lens unit F in order to reduce the size of the optical system and suppress the spherical aberration of the optical system. When the refractive power of the rear lens unit R decreases and fR / fF becomes higher than the upper limit of inequality (3), the overall length of the optical system increases. When the refractive power of the rear lens unit R increases, it becomes difficult to correct the spherical aberration that appears in the rear lens unit R.

[0054] Inequality (4) defines an appropriate relationship between the focal length of the rear lens unit R and the focal length of the first negative lens Rn1 in order to reduce color shading and suppress field curvature. When the refractive power of the lens Rn1 increases, it becomes difficult to correct the field curvature that appears in the rear lens unit R. When the refractive power of the first negative lens Rn1 decreases and fR / fRn1 becomes lower than the lower limit of inequality (4), the incident height of off-axis light incident on the second positive lens Rp2 decreases, the incident angle of the light incident on the image sensor increases, and the color shading becomes obvious.

[0055] Inequality (5) defines an appropriate relationship between the focal length of the second positive lens Rp2 and the focal length of the first negative lens Rn1 in order to suppress the coma aberration and distortion that appear in the rear lens unit R and reduce color shading. When the refractive power of the second positive lens Rp2 decreases and fRp2 / fRn1 becomes higher than the upper limit of inequality (5), the incident angle of the light on the image sensor increases, and the color shading becomes obvious. When the refractive power of the second positive lens Rp2 increases and fRp2 / fRn1 becomes lower than the lower limit of inequality (5), it becomes difficult to correct the coma aberration and distortion that appear in the second positive lens Rp2.

[0056] Inequality (6) defines an appropriate relationship between the focal length of the second positive lens Rp2 and the focal length of the first positive lens Rp1 in order to reduce the size of the optical system and suppress the spherical aberration that appears in the rear lens unit R. When the refractive power of the first positive lens Rp1 increases and fRp2 / fRp1 becomes higher than the upper limit of inequality (6), it becomes difficult to correct the spherical aberration generated in the first positive lens Rp1. When the refractive power of the first positive lens Rp1 decreases and fRp2 / fRp1 becomes lower than the lower limit of inequality (6), the overall length and size of the optical system increase.

[0057] Inequality (7) defines an appropriate relationship between the focal length of the negative lens Fn and the focal length of the positive lens Fp in the front lens unit F, so as to reduce the size of the optical system and suppress the spherical aberration generated in the front lens unit F. In the case where the refractive power of the positive lens Fp increases and fFn / fFp becomes higher than the upper limit of inequality (7), it becomes difficult to correct the spherical aberration that appears in the positive lens Fp. In the case where the refractive power of the positive lens Fp decreases and fFp becomes lower than the lower limit of (7), the overall length and size of the optical system increase.

[0058] Inequality (8) defines an appropriate range of the shape factor of the air lens between the first negative lens Rn1 and the second negative lens Rn2, so as to suppress the field curvature and coma aberration that appear in the rear lens unit R. In the case where the radius of curvature of the object-side surface of the second negative lens Rn2 increases and (R2 + R1) / (R2 - R1) becomes higher than the upper limit of inequality (8), it becomes difficult to correct the field curvature that appears in the rear lens unit R. In the case where the radius of curvature of the object-side surface of the second negative lens Rn2 decreases and (R2 + R1) / (R2 - R1) becomes lower than the lower limit of inequality (8), it becomes difficult to correct the coma aberration that appears in the rear lens unit R.

[0059] Inequality (9) defines an appropriate range of the refractive index of the material of the first positive lens Rp1, so as to reduce the size of the optical system and suppress the spherical aberration and longitudinal chromatic aberration that appear in the first positive lens Rp1. In the case where the refractive index of the material of the first positive lens Rp1 increases and ndRp1 becomes higher than the upper limit of inequality (9), the dispersion of the lens increases, and it becomes difficult to correct the longitudinal chromatic aberration that appears in the first positive lens Rp1. In the case where the refractive index of the material of the first positive lens Rp1 decreases and ndRp1 becomes lower than the lower limit of inequality (9), the radius of curvature of the surface of the first positive lens Rp1 decreases in order to provide the first positive lens Rp1 with the required refractive power. On the other hand, in the case where the refractive power of the first positive lens Rp1 decreases, the convergence of light rays decreases, and the overall length and size of the optical system increase.

[0060] Inequality (10) defines an appropriate relationship between the overall optical length of the optical system and the focal length of the optical system, so as to achieve both a compact optical system and high performance. In the case where the overall optical length of the optical system increases and L / f becomes higher than the upper limit of inequality (10), the size of the optical system increases. In the case where the overall optical length of the optical system decreases and L / f becomes lower than the lower limit of inequality (10), the radius of curvature of each lens surface becomes smaller, higher-order aberrations become obvious, and it becomes difficult to achieve high performance of the optical system.

[0061] Inequality (11) defines an appropriate relationship between the back focal length of the optical system and the focal length of the optical system so as to reduce the size and color shading of the optical system. When the back focal length of the optical system increases and sk / f becomes higher than the upper limit of inequality (11), the size of the optical length and the total length increase. When the back focal length of the optical system decreases and sk / f becomes lower than the lower limit of (11), the incident angle of light on the image sensor increases, and the color shading becomes obvious.

[0062] Inequality (12) defines an appropriate relationship between the distance from the foremost surface of the optical system to the incident pupil position and the focal length of the optical system so as to suppress coma and distortion in the optical system and reduce the size of the optical system. When the incident pupil position moves toward the image side and t1 / f becomes higher than the upper limit of inequality (12), the diameter of the lens closest to the object increases, and the size of the optical system increases. When the incident pupil position moves toward the object side and t1 / f becomes lower than the lower limit of inequality (12), the negative refractive power of the front lens unit F increases, and it becomes difficult to correct the coma and distortion generated in the front lens unit F.

[0063] Inequalities (2) to (12) can be replaced by the following inequalities (2a) to (12a):

[0064] -0.6 ≤ f / fF ≤ 1.2 (2a)

[0065] -0.7 ≤ fR / fF ≤ 2.2 (3a)

[0066] -5.5 ≤ fR / fRn1 ≤ -1.6 (4a)

[0067] -3.0 ≤ fRp2 / fRn1 ≤ -1.2 (5a)

[0068] 0.8 ≤ fRp2 / fRp1 ≤ 4.0 (6a)

[0069] -1.6 ≤ fFn / fFp ≤ -0.2 (7a)

[0070] -0.7 ≤ (R2 + R1) / (R2 - R1) ≤ 0.2 (8a)

[0071] 1.7 ≤ ndRp1 ≤ 2.1 (9a)

[0072] 2.3 ≤ L / f ≤ 5.0 (10a)

[0073] 0.40 ≤ sk / f ≤ 0.82 (11a)

[0074] 0.3 ≤ t1 / f ≤ 1.2 (12a)

[0075] Inequalities (2) to (12) can be replaced with the following inequalities (2b) to (12b):

[0076] -0.4 ≤ f / fF ≤ 1.0 (2b)

[0077] -0.5 ≤ fR / fF ≤ 2.0 (3b)

[0078] -5.0 ≤ fR / fRn1 ≤ -1.8 (4b)

[0079] -2.8 ≤ fRp2 / fRn1 ≤ -1.4 (5b)

[0080] 1.0 ≤ fRp2 / fRp1 ≤ 3.5 (6b)

[0081] -1.2 ≤ fFn / fFp ≤ -0.3 (7b)

[0082] -0.6 ≤ (R2 + R1) / (R2 - R1) ≤ 0.1 (8b)

[0083] 1.8 ≤ ndRp1 ≤ 2.0 (9b)

[0084] 2.6 ≤ L / f ≤ 4.5 (10b)

[0085] 0.5 ≤ sk / f ≤ 0.7 (11b)

[0086] 0.4 ≤ t1 / f ≤ 1.1 (12b)

[0087] Now, the optical systems according to Examples 1 to 5 will be specifically described.

[0088] In Examples 1, 3, 4, and 5, the front lens unit F includes a negative lens Fn and a positive lens Fp in order from the object side. In Example 2, the front lens unit F includes a negative lens Fn and a positive lens Fp in order from the object side. The rear lens unit R includes a negative lens Fn, a positive lens, and a positive lens Fp.

[0089] In Examples 1, 2, 3, and 4, the rear lens unit R includes a cemented lens in which a first positive lens Rp1 and a first negative lens Rn1 are cemented together, a second negative lens Rn2, and a second positive lens Rp2 in order from the object side. In Example 5, the rear lens unit R includes a cemented lens in which a first positive lens Rp1 and a first negative lens Rn1 are cemented together, a second negative lens Rn2, a second positive lens Rp2, and a third positive lens in order from the object side. As described above, the optical system according to each example includes six or more lenses (a cemented lens in which two lenses are cemented together is counted as two lenses).

[0090] In each example, the negative lens closest to the object can achieve a wide angle of the optical system.

[0091] The rear lens unit R including the first negative lens Rn1 and the second positive lens Rp2 on the image side of the first negative lens Rn1 can reduce the incident angle of off-axis light rays on the image sensor. Thereby, color shading can be reduced.

[0092] The first positive lens Rp1 deployed on the object side of the second positive lens Rp2 in the rear lens unit R and made of a material with a high refractive index can reduce the size of the optical system by effectively converging light rays and by satisfactorily correcting the spherical aberration generated by the first negative lens Rn1. In addition, the second positive lens Rp2 adjacent to the first negative lens Rn1 via an air gap and deployed on the image side of the first negative lens Rn1 can satisfactorily correct the coma aberration and field curvature that occur in the rear lens unit R. Thereby, a reduced size and a large aperture of the optical system can be achieved.

[0093] Regarding focusing, Example 1 adopts an overall movement method that moves the entire optical system toward the object during focusing from an object at infinity to an object at a short distance. Example 2 adopts a front focusing method that moves the sub-unit (front lens unit F, aperture stop SP, and the first positive lens Rp1 and the first negative lens Rn1 in the rear lens unit R) including the lens closest to the object in the optical system integrally toward the object side during focusing. Examples 3 and 4 use a rear focusing method that moves the sub-unit including the lens closest to the image plane in the optical system integrally. In Example 3, the aperture stop SP and the rear lens unit R move together toward the object side, and in Example 4, the rear lens unit R moves toward the object side. Example 5 adopts a floating focusing system that moves two different sub-units (the positive lens Fp in the front lens unit F and the rear lens unit R) in the optical system along different trajectories toward the object side during focusing.

[0094] Now, numerical examples 1 to 5 corresponding to Examples 1 to 5 will be described. In each numerical example, the surface number indicates the order of the surfaces starting from the object side. r represents the radius of curvature of the i-th surface (mm), d represents the lens thickness or air gap on the optical axis between the i-th surface and the (i + 1)-th surface (mm). nd represents the refractive index for the d-line of the optical material between the i-th surface and the (i + 1)-th surface, νd represents the Abbe number based on the d-line of the optical material, and the effective diameter is the effective diameter of the light rays of the i-th surface.

[0095] The Abbe number vd based on the d-line is expressed as follows:

[0096] νd = (nd - 1) / (nF - nC)

[0097] where nd, nF, and nC are the refractive indices for the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) in the Fraunhofer lines, respectively.

[0098] BF represents the back focal length (mm). The back focal length is the distance on the optical axis from the lens surface (the last surface) closest to the image plane of the optical system to the paraxial image plane, and is expressed based on the air equivalent length. The total lens length (mm) is the distance on the optical axis from the frontmost surface to the last surface of the optical system plus the back focal length, which corresponds to the total optical length.

[0099] The asterisk "*" next to the surface number indicates that the lens surface has an aspherical shape. The aspherical shape is represented by the following equation:

[0100] x = (h 2 / R) / [1 + {1 - (1 + K)(h / R) 2}] 1 / 2 + A4 × h 4 + A6 × h 6 + A8 × h 8 + A8 × h 8 + A10 × h 10 where x is the displacement amount from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are aspherical coefficients. "e±M" in the conic constant and aspherical coefficients means ×10 ±M .

[0101] Table 1 summarizes the values of inequalities (1) to (12) in Numerical Examples 1 to 5. The optical systems according to each numerical example satisfy all inequalities (1) to (12).

[0102] Figure 2 , Figure 4 , Figure 6 , Figure 8 and Figure 10 respectively illustrate the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the optical systems according to Numerical Examples 1 to 5. In the spherical aberration diagram, Fno indicates the F-number. The solid line indicates the amount of spherical aberration for the d-line (wavelength 587.6 nm), and the alternating long and two short dashed lines indicate the amount of spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagram, the dashed line ΔM indicates the amount of astigmatism on the sagittal image plane, and the dashed line ΔM indicates the amount of astigmatism on the meridional image plane. The distortion diagram illustrates the amount of distortion for the d-line. The chromatic aberration diagram illustrates the amount of lateral chromatic aberration for the g-line. ω is the semi-field angle (°).

[0103] Numerical Example 1

[0104] Unit: mm

[0105] Surface data

[0106]

[0107] Aspherical data

[0108] The 3rd surface

[0109] K = 0.00000e+000 A4 = 3.42924e-004 A6 = 5.40239e-008 A8 = 7.15673e-007

[0110] The 4th surface

[0111] K = 0.00000e+000 A4 = -2.06201e-005 A6 = -3.16817e-006 A8 = 7.24155e-007

[0112] The 9th surface

[0113] K = 0.00000e+000 A4 = 2.41018e-003 A6 = 1.49517e-004 A8 = 7.38145e-006 A10 = -8.67755e-007 A12 = 7.20535e-008

[0114] The 10th surface

[0115] K = 0.00000e+000 A4 = 1.79265e-003 A6 = 7.50567e-005 A8 = 2.80419e-007 Various data

[0116] Single lens data

[0117] Numerical example 2 Unit: mm Surface data

[0118]

[0119] Aspherical data

[0120] The 5th surface

[0121] K = 0.00000e+000 A4 = -1.20930e-004 A6 = -1.54004e-006 A8 = 3.10157e-008

[0122] The 6th surface

[0123] K = 0.00000e+000 A4 = -1.80501e-005 A6 = -1.39998e-006 A8 = 5.23245e-008

[0124] The 11th surface

[0125] K = 0.00000e+000 A4 = 2.37707e-003 A6 = -1.46625e-005 A8 = 7.89300e-006 A10 = -6.07443e-007 A12 = 1.31406e-008

[0126] The 12th surface

[0127] K = 0.00000e+000 A4 = 1.61376e-003 A6 = 6.13982e-006 A8 = 1.14249e-006 A10 = -7.30382e-008 A12 = 8.76937e-010

[0128] Various data

[0129]

[0130]

[0131] Single lens data

[0132] Numerical example 3 Unit: mm Surface data

[0133]

[0134] Aspherical data

[0135] The 3rd surface

[0136] K = 0.00000e+000 A4 = 3.82508e-004 A6 = -4.13980e-006 A8 = 1.12882e-006 A10 = -3.79296e-008 A12 = 7.27467e-010

[0137] The 4th surface

[0138] K = 0.00000e+000 A4 = 4.87047e-005 A6 = -7.07670e-006 A8 = 1.06393e-006 A10 = -5.13271e-008 A12 = 1.69678e-009

[0139] The 9th surface

[0140] K = 0.00000e+000, A4 = 9.24841e-004, A6 = 6.23435e-005, A8 = 7.91063e-006, A10 = -3.42356e-007, A12 = 1.27129e-008

[0141] The 10th surface

[0142] K = 0.00000e+000, A4 = 9.90906e-004, A6 = 3.91752e-005, A8 = 1.59837e-006, A10 = -2.31958e-009, A12 = -1.36600e-009

[0143] Various data

[0144]

[0145] Single lens data

[0146]

[0147]

[0148] Numerical example 4

[0149] Unit: mm

[0150] Surface data

[0151]

[0152] Aspherical data

[0153] The 3rd surface

[0154] K = 0.00000e+000, A4 = 4.92834e-005, A6 = -7.58139e-007, A8 = 9.66877e-009, A10 = 5.28887e-010, A12 = -3.82528e-011

[0155] The 4th surface

[0156] K = 0.00000e+000, A4 = -2.87709e-005, A6 = -1.94063e-006, A8 = 1.07057e-008, A10 = 6.57759e-010, A12 = -3.75875e-011

[0157] The 9th surface

[0158] K = 0.00000e+000 A4 = 1.26314e-004 A6 = -2.69131e-005 A8 = 9.33030e-007 A10 = 8.34209e-008 A12 = -5.77848e-009

[0159] The 10th surface

[0160] K = 0.00000e+000 A4 = 4.86267e-004 A6 = -4.20015e-006 A8 = 8.70440e-007 A10 = -6.49799e-009 A12 = -5.42622e-011

[0161] Various data

[0162]

[0163] Single lens data

[0164]

[0165] Numerical example 5

[0166] Unit: mm

[0167] Surface data

[0168]

[0169] Aspherical data

[0170] The 3rd surface

[0171] K = 0.00000e+000 A4 = -3.31939e-005 A6 = 1.00057e-007 A8 = -2.74914e-008

[0172] The 4th surface

[0173] K = 0.00000e+000 A4 = -2.85162e-005 A6 = 1.59757e-007 A8 = -2.80716e-008

[0174] The 9th surface

[0175] K = 0.00000e+000 A4 = 7.25303e-004 A6 = -1.24640e-005 A8 = 8.86812e-007 A10 = -7.98689e-008

[0176] The 10th surface

[0177] K = 0.00000e+000 A4 = 1.09100e-003 A6 = -9.24396e-006 A8 = -6.60088e-008 A10 = 3.33401e-009

[0178] Various data

[0179]

[0180] Single lens data

[0181]

[0182]

[0183]

[0184] Image pickup device

[0185] Figure 13 The figure shows an image pickup device (digital still camera) using any one of the stereo optical systems according to Examples 1 to 5. In Figure 13 it, ID represents the camera body, and SO represents an imaging optical system SO including one of the stereo optical systems (right optical system OSR and left optical system OSL) according to Examples 1 to 5. The imaging optical system SO can be attached to the camera body ID and can be detached from the camera body ID, or can be integrated with the camera body ID. S represents an image sensor such as a CCD sensor or a CMOS sensor that is built in the camera body ID and performs photoelectric conversion on the optical image formed by the imaging optical system SO (i.e., captures an object).

[0186] The image pickup device can be a single-lens reflex camera with a fast steering mirror or a mirrorless camera without a fast steering mirror.

[0187] An image pickup device using a stereo optical system according to any one of Examples 1 to 5 as its imaging optical system can obtain a bright image with a good three-dimensional effect and a reduced overall size.

[0188] Although the present disclosure has described exemplary embodiments, it should be understood that the present disclosure is not limited to the exemplary embodiments. The scope of the appended claims will be given the broadest interpretation to include all such modifications and equivalent structures and functions.

[0189] Each example can provide a stereo optical system with a reduced size and a large aperture, and can perform imaging with a good three-dimensional effect.

Claims

1. A stereoscopic optical system, comprising: Two optical systems arranged in parallel, It is characterized in that each of the two optical systems comprises an aperture stop and at least two positive lenses disposed on the image side of the aperture stop, Among them, the following inequality is satisfied: 1.8≤D / (f tanω)≤5.5 Wherein D is the distance between the optical axes of the two optical systems, f is the focal length of each of the two optical systems, and ω is the maximum half viewing angle of each of the two optical systems.

2. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a front lens unit on the object side of the aperture stop, Among them, the following inequality is satisfied: -1.0≤f / fF≤1.4 Where fF is the focal length of the front lens unit.

3. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a rear lens unit on the image side of the aperture stop, Among them, the following inequality is satisfied: -0.9≤fR / fF≤2.4 Where fR is the focal length of the rear lens unit.

4. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a rear lens unit on the image side of the aperture stop, Among them, the following inequality is satisfied: -6.0≤fR / fRn1≤-1.4 Wherein fRn1 is the focal length of a first negative lens having the strongest refractive power among at least one negative lens included in the rear lens unit.

5. The stereoscopic optical system according to claim 4, characterized in that: The following inequalities are satisfied: -3.2≤fRp2 / fRn1≤-1.0 Wherein fRp2 is the focal length of the second positive lens having the strongest refractive power among at least one positive lens disposed on the image side of the first negative lens in the rear lens unit.

6. The stereoscopic optical system according to claim 5, characterized in that: The following inequalities are satisfied: 0.4≤fRp2 / fRp1≤4.5 Wherein fRp1 is the focal length of the first positive lens having the strongest refractive power among at least one positive lens disposed on the object side of the second positive lens in the rear lens unit.

7. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a front lens unit on the object side of the aperture stop, Among them, the following inequality is satisfied: -2.0≤fFn / fFp≤-0.1 Wherein fFn is the focal length of the negative lens having the strongest refractive power among at least one negative lens included in the front lens unit, and fFp is the focal length of the positive lens having the strongest refractive power among at least one positive lens included in the front lens unit.

8. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a rear lens unit on the image side of the aperture stop, Among them, the following inequality is satisfied: -0.8≤(R2+R1) / (R2-R1)≤0.3 Wherein R1 is the curvature radius of the image-side surface of a first negative lens having the strongest refractive power among at least one negative lens included in the rear lens unit, and R2 is the curvature radius of the object-side surface of a second negative lens adjacent to the first negative lens via an air gap and disposed on the image side of the first negative lens.

9. The stereoscopic optical system according to claim 6, characterized in that: The following inequalities are satisfied: 1.6≤ndRp1≤2.2 Here, ndRp1 is the refractive index of the material of the first positive lens for the d-line.

10. The stereoscopic optical system according to claim 1, characterized in that: The following inequalities are satisfied: 2.0≤L / f≤5.5 Wherein L is the distance on the optical axis from the surface of each of the two optical systems closest to the object to the image plane.

11. The stereoscopic optical system according to claim 1, characterized in that: The following inequalities are satisfied: 0.3≤sk / f≤0.9 Wherein sk is the back focal length of each of the two optical systems.

12. The stereoscopic optical system according to claim 1, characterized in that: The following inequalities are satisfied: 0.2≤t1 / f≤1.3 wherein t1 is the distance on the optical axis from the surface of each of the two optical systems closest to the object to the entrance pupil position.

13. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes six or more lenses.

14. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a positive lens closest to the image plane.

15. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes a negative lens closest to the object.

16. The stereoscopic optical system according to claim 1, characterized in that: Each of the two optical systems includes at least one lens that moves during focusing.

17. The stereoscopic optical system according to claim 1, characterized in that: Two optical images formed by the two optical systems are formed on a single image sensor.

18. The stereoscopic optical system according to claim 1, characterized in that: In each of the two optical systems, a front lens unit disposed on the object side of the aperture stop includes, in order from the object side to the image side, a negative lens and a positive lens, Among them, the rear lens unit arranged on the image side of the aperture stop includes a cemented lens, a second negative lens and a second positive lens in sequence from the object side to the image side, in which the first positive lens and the first negative lens are cemented together.

19. The stereoscopic optical system according to claim 1, characterized in that: In each of the two optical systems, a front lens unit disposed on the object side of the aperture stop includes, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens, Among them, the rear lens unit arranged on the image side of the aperture stop includes a cemented lens, a second negative lens and a second positive lens in sequence from the object side to the image side, in which the first positive lens and the first negative lens are cemented together.

20. The stereoscopic optical system according to any one of claims 1 to 19, characterized in that: In each of the two optical systems, a front lens unit disposed on the object side of the aperture stop includes, in order from the object side to the image side, a negative lens and a positive lens, Among them, the rear lens unit deployed on the image side of the aperture stop includes a cemented lens, a second negative lens, a second positive lens and a third positive lens in sequence from the object side to the image side, in which the first positive lens and the first negative lens are cemented together.

21. An image pickup device, comprising: A stereoscopic optical system according to any one of claims 1 to 20; as well as An image sensor is used to capture an image of an object through the stereoscopic optical system.

Images