Imaging optical system and imaging device

Abstract

An imaging optical system according to the present disclosure comprises: a first lens group; a second lens group having positive refractive power; and a third lens group having negative refractive power. The second lens group moves in an optical axis direction during focusing, a conditional expression (1) is satisfied for a focal length f2 of the second lens group and a focal length f3 of the third lens group, and the second lens group has a positive lens that satisfies conditional expressions (2), (3). θgF is the partial dispersion ratio between the g-line and the F-line of the positive lens, and νd is the Abbe number based on the d-line of the positive lens.　(1): -0.80 < f2 / f3 < -0.25; (2): θgF+0.00325*νd > 0.6825; (3): νd < 25.0

Description

Imaging optical system and imaging device

[0001] The present disclosure relates to an imaging optical system and an imaging device.

[0002] In recent years, imaging devices such as digital cameras have become larger and have a higher number of pixels, and imaging lenses used in these imaging devices are also required to have high optical performance. On the other hand, imaging devices are becoming smaller in size from the perspective of convenience, and so there is a demand for smaller optical systems. Furthermore, as the number of situations in which imaging devices are used to capture not only still images but also videos is increasing, there is a demand for performance that is compatible with video capture, such as suppression of fluctuations in the angle of view during focusing.

[0003] JP 2007-94174 A JP 2018-18041 A

[0004] In Patent Documents 1 and 2, a retrofocus type lens is used to achieve a wide-angle lens while ensuring a sufficient flange focal distance. However, the power of each lens group is inappropriate, resulting in a large fluctuation rate of the angle of view during focusing. Furthermore, the lens material used in the focus group is inappropriately selected, resulting in a structure that makes it difficult to correct chromatic aberration when focusing at a finite distance.

[0005] Therefore, it is desirable to provide an imaging optical system that corrects various aberrations, is compact, and is capable of suppressing fluctuations in the angle of view that accompany focusing, and an imaging apparatus that includes such an imaging optical system.

[0006] An imaging optical system according to an embodiment of the present disclosure includes, in order from the object side to the image plane side, a first lens group, a second lens group having positive refractive power, and a third lens group having negative refractive power, wherein the second lens group moves in the optical axis direction during focusing, and the focal lengths of the second lens group and the third lens group satisfy the following conditional expression (1), and the second lens group includes a positive lens that satisfies the following conditional expressions (2) and (3): −0.80<f2 / f3<−0.25 (1) θgF+0.00325*νd>0.6825 (2) νd<25.0 (3) where, f2: focal length of the second lens group, f3: focal length of the third lens group, θgF: partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group, and νd: Abbe number based on the d-line of the positive lens in the second lens group.

[0007] An imaging device according to one embodiment of the present disclosure includes an imaging optical system and an imaging element that outputs an imaging signal corresponding to an optical image formed by the imaging optical system, and the imaging optical system is configured using the imaging optical system according to the embodiment of the present disclosure.

[0008] In an imaging optical system or an imaging device according to an embodiment of the present disclosure, the configuration of each lens group is optimized so that various aberrations are corrected, the device is compact, and fluctuations in the angle of view associated with focusing can be suppressed.

[0009] FIG. 1 is a lens cross-sectional view showing a first configuration example (Example 1) of an imaging optical system according to an embodiment of the present disclosure. FIG. 2 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 1 when focusing at infinity. FIG. 3 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 1 when focusing at a close distance. FIG. 4 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 1 when focusing at infinity. FIG. 5 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 1 when focusing at a close distance. FIG. 6 is a lens cross-sectional view showing a second configuration example (Example 2) of an imaging optical system according to an embodiment. FIG. 7 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 2 when focusing at infinity. FIG. 8 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 2 when focusing at a close distance. FIG. 9 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 2 when focusing at infinity. FIG. 10 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 2 when focusing at a close distance. FIG. 11 is a lens cross-sectional view showing a third configuration example (Example 3) of an imaging optical system according to an embodiment. FIG. 12 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 3 when focusing at infinity. FIG. 13 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 3 when focusing at a close distance. FIG. 14 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 3 when focusing at infinity. FIG. 15 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 3 when focusing at a close distance. FIG. 16 is a lens cross-sectional view showing a fourth configuration example (Example 4) of an imaging optical system according to an embodiment. FIG. 17 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 4 when focusing at infinity. FIG. 18 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 4 when focusing at a close distance. FIG. 19 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 4 when focusing at infinity. FIG. 20 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 4 when focusing at a close distance. Fig. 21 is a lens cross-sectional view showing a fifth configuration example (Example 5) of an imaging optical system according to an embodiment. Fig. 22 is an aberration diagram showing longitudinal aberration when the imaging optical system according to Example 5 is focused at infinity. Fig. 23 is an aberration diagram showing longitudinal aberration when the imaging optical system according to Example 5 is focused at a close distance. Fig. 24 is an aberration diagram showing lateral aberration when the imaging optical system according to Example 5 is focused at infinity.FIG. 25 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 5 when focusing on a close distance. FIG. 26 is a lens cross-sectional view showing a sixth configuration example (Example 6) of the imaging optical system according to one embodiment. FIG. 27 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 6 when focusing on infinity. FIG. 28 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 6 when focusing on a close distance. FIG. 29 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 6 when focusing on infinity. FIG. 30 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 6 when focusing on a close distance. FIG. 31 is a lens cross-sectional view showing a seventh configuration example (Example 7) of the imaging optical system according to one embodiment. FIG. 32 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 7 when focusing on infinity. FIG. 33 is an aberration diagram showing longitudinal aberration of the imaging optical system according to Example 7 when focusing on a close distance. FIG. 34 is an aberration diagram showing lateral aberration of the imaging optical system according to Example 7 when focusing on infinity. Fig. 35 is an aberration diagram showing lateral aberration when the imaging optical system according to Example 7 is focused on a close distance. Fig. 36 is a block diagram showing an example of the configuration of an imaging device. Fig. 37 is a block diagram showing an example of the schematic configuration of a vehicle control system. Fig. 38 is an explanatory diagram showing an example of the installation positions of an outside-of-vehicle information detection unit and an imaging unit. Fig. 39 is a diagram showing an example of the schematic configuration of an endoscope system. Fig. 40 is a block diagram showing an example of the functional configuration of the camera and CCU shown in Fig. 39. Fig. 41 is a diagram showing an example of the schematic configuration of a microsurgical system.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order: 1. Basic configuration of optical system 2. Actions and effects 3. Application example to imaging device 4. Numerical example of optical system 5. Application example 6. Other embodiments

[0011] 1. Basic Configuration of Optical System FIG. 1 illustrates a first configuration example of an imaging optical system according to an embodiment of the present disclosure, which corresponds to the configuration of Example 1 described below. FIG. 6 illustrates a second configuration example of an imaging optical system according to an embodiment, which corresponds to the configuration of Example 2 described below. FIG. 11 illustrates a third configuration example of an imaging optical system according to an embodiment, which corresponds to the configuration of Example 3 described below. FIG. 16 illustrates a fourth configuration example of an imaging optical system according to an embodiment, which corresponds to the configuration of Example 4 described below. FIG. 21 illustrates a fifth configuration example of an imaging optical system according to an embodiment, which corresponds to the configuration of Example 5 described below. FIG. 26 illustrates a sixth configuration example of an imaging optical system according to an embodiment, which corresponds to the configuration of Example 6 described below. FIG. 31 illustrates a seventh configuration example of an imaging optical system according to an embodiment, which corresponds to the configuration of Example 7 described below.

[0012] The imaging optical system according to one embodiment is suitable for imaging devices such as single-lens cameras, digital still cameras, film cameras, video cameras, broadcast cameras, and surveillance cameras.

[0013] In FIG. 1 and other figures, Z1 indicates the optical axis. An optical member such as a cover glass for protecting the imaging element may be disposed between the imaging optical systems 1 to 7 according to the first to seventh configuration examples and the image plane. In addition to the cover glass, various optical filters such as a low-pass filter and an infrared cut filter may be disposed as optical members. When the imaging optical system according to an embodiment is applied to a digital still camera, a video camera, or the like, the image plane of the imaging optical system corresponds to the imaging plane of an imaging element such as a CCD (Charge Coupled Devices) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. When the imaging optical system according to an embodiment is applied to a film camera, the image plane of the imaging optical system corresponds to the film plane.

[0014] 1 etc., the lens arrangement when focusing at infinity is shown. In addition, in FIG. 1 etc., the left side indicates the object side and the right side indicates the image plane side.

[0015] Below, the configuration of an imaging optical system according to one embodiment of the present disclosure will be described in association with imaging optical systems 1 to 7 according to the configuration examples shown in FIG. 1 and the like, as appropriate; however, the technology according to the present disclosure is not limited to the configuration examples shown in the drawings.

[0016] An imaging optical system according to one embodiment comprises, in order from the object side to the image plane side, a first lens group G1, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power.

[0017] In addition, in the imaging optical system according to one embodiment, the second lens group G2 moves parallel to the optical axis direction during focusing.

[0018] An imaging optical system according to one embodiment satisfies the following conditional expression (1) regarding the focal length of the second lens group G2 and the focal length of the third lens group G3. The second lens group G2 also has a positive lens that satisfies the following conditional expressions (2) and (3): -0.80<f2 / f3<-0.25 (1) θgF+0.00325*νd>0.6825 (2) νd<25.0 (3) where, f2: focal length of the second lens group G2, f3: focal length of the third lens group G3, θgF: partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group G2, and νd: Abbe number of the positive lens in the second lens group G2 based on the d-line.

[0019] In addition, the imaging optical system according to one embodiment may further satisfy certain conditional expressions, etc., which will be described later.

[0020] 2. Actions and Effects Next, actions and effects of the imaging optical system according to one embodiment of the present disclosure will be described. Additionally, a more preferable configuration of the imaging optical system according to one embodiment of the present disclosure, and its actions and effects will be described. Note that the effects described in this specification are merely examples and are not intended to be limiting, and other effects may also be present.

[0021] According to an embodiment of the imaging optical system, the configuration of each lens group is optimized so that various aberrations are corrected, the system is compact, and fluctuations in the angle of view due to focusing can be suppressed. This makes it possible to provide an imaging optical system that corrects various aberrations, is compact, and can suppress fluctuations in the angle of view due to focusing, as well as an imaging device that includes such an imaging optical system.

[0022] According to an imaging optical system of one embodiment, by providing each lens group with an appropriate power distribution and using appropriate glass materials for each lens group, it is possible to suppress fluctuations in the angle of view that occur during focusing, while also achieving compactness and weight reduction and high image quality. According to an imaging optical system of one embodiment, by arranging, in order from the object side to the image plane side, a first lens group G1, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power, it is possible to perform good aberration correction throughout the entire system and prevent the entire lens system from becoming large.

[0023] Conditional expression (1) defines a preferable range for the power distribution of the second lens group G2 and the third lens group G3. If the lower limit of conditional expression (1) is not met, the lateral magnification cannot be ensured, and the amount of movement of the focus group to achieve focusing at the desired close distance becomes large, making it difficult to achieve compactness. On the other hand, if the upper limit of conditional expression (1) is exceeded, the power of the third lens group G3 becomes relatively weak, making it difficult to correct fluctuations in the angle of view caused by the focus group, and therefore making it difficult to suppress the rate of fluctuation in the angle of view.

[0024] It should be noted that a better effect can be obtained by setting the upper limit to −0.4 and the lower limit to −0.6 in conditional expression (1).

[0025] Conditional expressions (2) and (3) define the partial dispersion ratio θgF and Abbe number vd of a predetermined positive lens in the second lens group G2 within preferred ranges for effectively correcting lateral chromatic aberration. If the partial dispersion ratio θgF does not satisfy conditional expression (2), the anomalous dispersion of the predetermined positive lens becomes small, making second-order achromatization difficult. If the Abbe number vd does not satisfy conditional expression (3), second-order dispersion becomes too large, making second-order achromatization difficult.

[0026] It should be noted that by setting the lower limit of conditional expression (2) to 0.6925 and the upper limit of conditional expression (3) to 20, a better effect can be obtained.

[0027] The imaging optical system according to one embodiment may also satisfy the following conditional expression (4): 0.9<|f1 / f|<5.0 (4) where, f1: focal length of the first lens group G1, and f: focal length of the entire system when focused at infinity.

[0028] If the lower limit of conditional expression (4) is exceeded, the power of the first lens group G1 becomes too strong, making it difficult to correct various aberrations that occur in the first lens group G1, whereas if the upper limit of conditional expression (4) is exceeded, the power of the first lens group G1 becomes too weak, making it difficult to reduce the size of the entire system.

[0029] It should be noted that by setting the upper limit to 4.5 and the lower limit to 2.0 in conditional expression (4), a better effect can be obtained.

[0030] The imaging optical system according to one embodiment may also satisfy the following conditional expression (5): 1.0<f2 / f<3.0 (5) where f2 is the focal length of the second lens group G2, and f is the focal length of the entire system when focused at infinity.

[0031] If the lower limit of conditional expression (5) is not reached, the power of the second lens group G2 becomes too strong, making it difficult to correct various aberrations that occur in the second lens group G2. If the upper limit of conditional expression (5) is reached, the power of the second lens group G2 becomes too weak, making it impossible to ensure the lateral magnification of the second lens group G2, and the amount of movement of the second lens group G2 becomes too large to achieve focusing at a desired close distance, making it difficult to achieve a compact size.

[0032] It should be noted that by setting the upper limit to 2.2 and the lower limit to 1.3 in conditional expression (5), a better effect can be obtained.

[0033] The imaging optical system according to one embodiment may also satisfy the following conditional expression (6): −7.0<f3 / f<−2.0 (6) where f3 is the focal length of the third lens group G3, and f is the focal length of the entire system when focused at infinity.

[0034] If the lower limit of conditional expression (6) is exceeded, the power of the third lens group G3 becomes weak, and it becomes necessary to increase the back focus to obtain a desired image height, making it difficult to achieve compactness.If the upper limit of conditional expression (6) is exceeded, the power of the third lens group G3 becomes strong, and the angle of incidence of peripheral rays with respect to the imaging surface becomes small, making it difficult to obtain good image quality.

[0035] It should be noted that by setting the upper limit to −2.4 and the lower limit to −6.7 in conditional expression (6), a better effect can be obtained.

[0036] The imaging optical system according to one embodiment may also satisfy the following conditional expression (7): 0.5<BF / f<1.2 (7) where BF is the distance on the optical axis from the lens surface closest to the image plane to the image plane, and f is the focal length of the entire system when focused at infinity.

[0037] If the lower limit of conditional expression (7) is exceeded, the back focus relative to the focal length of the entire system becomes too short, making it difficult to configure the mechanism on the image plane side, whereas if the upper limit of conditional expression (7) is exceeded, the back focus relative to the focal length of the entire system becomes too long, making it difficult to achieve compact size.

[0038] It should be noted that by setting the upper limit to 1.1 and the lower limit to 0.65 in conditional expression (7), a better effect can be obtained.

[0039] In an imaging optical system according to an embodiment, the first lens group G1 may have an aperture stop St that is fixed relative to the image plane during focusing. By fixing the aperture stop St relative to the image plane during focusing, it is possible to reduce the load on the actuator during focusing, making it easier to reduce the diameter of the entire system, including the lens movement mechanism.

[0040] In the imaging optical system according to one embodiment, the second lens group G2 may have an aspherical lens closest to the image surface. When shortening the overall optical length of the imaging optical system according to one embodiment, field curvature is likely to occur. By disposing an aspherical lens at the position closest to the image surface of the second lens group G2, where the difference between the axial ray height and the off-axial ray height becomes large, it becomes possible to correct field curvature without significantly increasing the number of lenses, thereby achieving both compactness and high imaging performance.

[0041] In the imaging optical system according to one embodiment, the first lens group G1 may have a negative lens closest to the object side. By including a lens with negative power closest to the object side in the first lens group G1, distortion can be corrected.

[0042] In the imaging optical system according to one embodiment, the first lens group G1 may include a plurality of lenses, and the second lens from the object side among the plurality of lenses in the first lens group G1 may have negative refractive power, which contributes to size reduction while appropriately correcting off-axis aberrations.

[0043] In the imaging optical system according to one embodiment, the first lens group G1 may have an aspherical lens closest to the image plane. By including an aspherical lens closest to the image plane in the first lens group G1, spherical aberration can be appropriately corrected, contributing to higher image quality.

[0044] In the imaging optical system according to one embodiment, the second lens group G2 may include a cemented lens. By including a cemented lens in the second lens group G2, chromatic aberration occurring in the second lens group G2 can be appropriately corrected, leading to higher image quality.

[0045] 3. Application Example to Imaging Device Next, a specific application example of the imaging optical system according to an embodiment of the present disclosure to an imaging device will be described.

[0046] 36 shows an example of the configuration of an imaging device 100 to which an imaging optical system according to one embodiment is applied. This imaging device 100 is, for example, a digital still camera, and includes a camera block 110, a camera signal processing unit 20, an image processing unit 30, an LCD (Liquid Crystal Display) 40, an R / W (Reader / Writer) 50, a CPU (Central Processing Unit) 60, an input unit 70, and a lens drive control unit 80.

[0047] The camera block 110 is responsible for the imaging function and includes an imaging lens 111 and an imaging element 112 such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The imaging element 112 converts an optical image formed by the imaging lens 111 into an electrical signal, and outputs an imaging signal (image signal) corresponding to the optical image. The imaging optical systems 1 to 7 according to the configuration examples shown in FIG. 1 and the like can be used as the imaging lens 111.

[0048] The camera signal processing unit 20 performs various signal processing on the image signal output from the image sensor 112, such as analog-to-digital conversion, noise removal, image quality correction, and conversion into luminance and color difference signals.

[0049] The image processing unit 30 performs recording and playback processing of image signals, and performs compression encoding and decompression decoding processing of image signals based on a predetermined image data format, conversion processing of data specifications such as resolution, etc.

[0050] The LCD 40 has a function of displaying various data such as the operation status of the user on the input unit 70 and captured images. The R / W 50 writes image data encoded by the image processing unit 30 to the memory card 1000 and reads image data recorded on the memory card 1000. The memory card 1000 is, for example, a semiconductor memory that is detachable from a slot connected to the R / W 50.

[0051] The CPU 60 functions as a control processing unit that controls each circuit block provided in the imaging device 100, and controls each circuit block based on instruction input signals and the like from the input unit 70. The input unit 70 is made up of various switches and the like that are operated as required by the user. The input unit 70 is composed of, for example, a shutter release button for operating the shutter and a selection switch for selecting an operation mode, and is configured to output instruction input signals to the CPU 60 in response to user operations. The lens drive control unit 80 controls the drive of the lenses arranged in the camera block 110, and is configured to control motors and the like (not shown) that drive each lens of the imaging lens 111 based on control signals from the CPU 60.

[0052] The following describes the operation of the imaging device 100. In a standby state for imaging, under the control of the CPU 60, an image signal corresponding to an image captured by the camera block 110 is output to the LCD 40 via the camera signal processing unit 20 and displayed as a camera-through image. Furthermore, when an instruction input signal for zooming or focusing is input from the input unit 70, for example, the CPU 60 outputs a control signal to the lens drive control unit 80, and a predetermined lens of the imaging lens 111 moves under the control of the lens drive control unit 80.

[0053] When a shutter (not shown) of the camera block 110 is operated in response to an instruction input signal from the input unit 70, the captured image signal is output from the camera signal processing unit 20 to the image processing unit 30, where it is compressed and encoded and converted into digital data in a predetermined data format. The converted data is output to the R / W 50 and written to the memory card 1000.

[0054] Focusing is performed by the lens drive control unit 80 moving a predetermined lens of the imaging lens 111 based on a control signal from the CPU 60, for example, when the shutter release button on the input unit 70 is pressed halfway or fully pressed for recording (photographing).

[0055] When reproducing image data recorded on memory card 1000, the R / W 50 reads out the specified image data from memory card 1000 in response to an operation on input unit 70, and after the image processing unit 30 performs an expansion / decoding process, the reproduced image signal is output to LCD 40 and the reproduced image is displayed.

[0056] Although the above-described embodiment shows an example in which the imaging device is applied to a digital still camera, the application range of the imaging device is not limited to digital still cameras and can be applied to various other imaging devices. For example, the imaging device can be applied to digital single-lens reflex cameras, digital non-reflex cameras, digital video cameras, surveillance cameras, etc. Furthermore, the imaging device can be widely used as a camera unit of digital input / output devices such as mobile phones with built-in cameras and information terminals with built-in cameras. Furthermore, the imaging device can be applied to cameras with interchangeable lenses.

[0057] 4. Numerical Examples of Optical Systems Next, specific numerical examples of the imaging optical system according to an embodiment of the present disclosure will be described. Here, examples will be described in which specific numerical values ​​are applied to imaging optical systems 1 to 7 according to the configuration examples shown in FIG. 1 and the like.

[0058] The meanings of symbols used in the following tables and explanations are as follows: "Si" indicates the number of the i-th surface, with the symbols increasing sequentially from the surface closest to the object. "ri" indicates the value (mm) of the paraxial radius of curvature of the i-th surface. "di" indicates the value (mm) of the axial distance between the i-th surface and the (i+1)-th surface. "ndi" indicates the value of the refractive index at the d-line (wavelength 587.6 nm) of the material of the optical element that comprises the i-th surface. "νdi" indicates the value of the Abbe number at the d-line of the material of the optical element that comprises the i-th surface. "θgFi" indicates the value of the partial dispersion ratio between the g-line and the F-line of the material of the optical element that comprises the i-th surface. "φi" indicates the value (mm) of the effective diameter of the i-th surface. A portion where the value of "ri" is "∞" indicates a flat surface, an aperture surface, etc. "ASP" in the surface number (Si) column indicates that the surface in question is configured as an aspheric surface. "STO" in the surface number column indicates that the aperture stop St is located at the corresponding position. "OBJ" in the surface number column indicates that the corresponding surface is the object plane (subject plane). "IMG" in the surface number column indicates that the corresponding surface is the image plane. "f" indicates the focal length of the entire system (unit: mm). "Fno" indicates the maximum open F-number. "ω" indicates the half angle of view (unit: °). "Y" indicates the maximum image height that determines the half angle of view (unit: mm). "L" indicates the total optical length (the distance on the optical axis from the surface closest to the object to the image plane IMG) (unit: mm).

[0059] Furthermore, some of the lenses used in the examples have aspherical lens surfaces. The aspherical shape is defined by the following formula. In the tables showing the aspherical coefficients described later, "E-i" is an exponential expression with the base 10, that is, "10 －ｉ " For example, "0.12345E-05" represents "0.12345 x 10 －５ " represents.

[0060] (Aspherical surface formula) x = cy ２ / (1+(1-(1+k)c ２ y ２ ) １／２ ) + A4・y ４ +A6・y ６ +A8・y ８ +A10·y１０ +A12·y １２ +A14·y １４ +A16・y １６ Here, the distance from the vertex of the lens surface in the optical axis direction (sag amount) is "x," the height in the direction perpendicular to the optical axis is "y," the paraxial curvature at the vertex of the lens surface (the reciprocal of the radius of curvature) is "c," and the conic constant is "k." A4, A6, A8, A10, A12, A14, and A16 are the 4th-, 6th-, 8th-, 10th-, 12th-, 14th-, and 16th-order aspheric coefficients, respectively.

[0061] [Example 1] Table 1 shows basic lens data for the imaging optical system 1 according to Example 1 shown in FIG. 1 . Table 2 shows values ​​for the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 1 according to Example 1. Table 3 shows data on surface spacings that are variable during focusing in the imaging optical system 1 according to Example 1. Table 2 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 3 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 4 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 1 according to Example 1. Table 5 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 1 according to Example 1.

[0062] The imaging optical system 1 according to Example 1 includes, in order from the object side to the image plane side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. An aperture stop St is located within the first lens group G1.

[0063] The first lens group G1 has positive refractive power. The first lens group G1 is composed of, in order from the object side to the image side, lenses L1 to L7 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side of the first lens group G1 has negative refractive power. The first lens group G1 has an aspherical lens (lens L7) closest to the image side.

[0064] In the first lens group G1, lens L1 is a negative meniscus lens with a convex surface facing the object side. Lens L2 is a negative meniscus lens with a convex surface facing the object side. Lens L3 is a negative biconcave lens. Lens L4 is a positive biconvex lens. Lens L5 is a negative biconcave lens. Lens L6 is a positive biconvex lens. Lens L7 is a positive biconvex lens. Lens L2 and lens L7 are each an aspherical lens with aspherical surfaces formed on both sides. Lenses L3 and L4 are cemented together to form a cemented lens. Lenses L5 and L6 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of seven lenses and five lens components.

[0065] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L8 to L14. The second lens group G2 has a positive lens (lens L12) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L14) closest to the image surface. The second lens group G2 has a cemented lens.

[0066] In the second lens group G2, lens L8 is a biconvex positive lens. Lens L9 is a positive meniscus lens with a concave surface facing the object side. Lens L10 is a biconcave negative lens. Lens L11 is a negative meniscus lens with a concave surface facing the object side. Lens L12 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L13 is a positive meniscus lens with a concave surface facing the object side. Lens L14 is a biconcave negative lens. Lens L14 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L9 and L10 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of seven lenses and six lens components.

[0067] The third lens group G3 has negative refractive power. The third lens group G3 is made up of the lens L15. The lens L15 is a negative biconcave lens. As described above, the third lens group G3 is made up of one lens, one lens component.

[0068] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L8 and the distance between the lenses L14 and L15 change.

[0069] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] Fig. 2 shows longitudinal aberration when the imaging optical system 1 according to Example 1 is focused at infinity. Fig. 3 shows longitudinal aberration when the imaging optical system 1 according to Example 1 is focused at a close distance. Fig. 4 shows lateral aberration when the imaging optical system 1 according to Example 1 is focused at infinity. Fig. 5 shows lateral aberration when the imaging optical system 1 according to Example 1 is focused at a close distance.

[0076] Figures 2 and 3 show spherical aberration, astigmatism (field curvature), and distortion as longitudinal aberrations. In the spherical aberration diagrams in Figures 2 and 3 and the lateral aberration diagrams in Figures 4 and 5, the solid line indicates values ​​at the d-line (587.56 nm), the dashed-dotted line indicates values ​​at the g-line (435.84 nm), and the dashed line indicates values ​​at the C-line (656.27 nm). In the astigmatism diagrams in Figures 2 and 3, S indicates values ​​at the sagittal image plane, and T indicates values ​​at the tangential image plane. The astigmatism diagrams and distortion diagrams in Figures 2 and 3 show values ​​at the d-line. The same applies to the aberration diagrams in the other examples that follow.

[0077] As can be seen from each aberration diagram, the imaging optical system 1 according to Example 1 has excellent correction of various aberrations and has excellent imaging performance.

[0078] Example 2 Table 6 shows basic lens data for the imaging optical system 2 according to Example 2 shown in FIG. 6 . Table 7 shows values ​​for the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 2 according to Example 2. Table 8 shows data on surface spacings that are variable during focusing in the imaging optical system 2 according to Example 2. Table 7 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 8 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 9 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 2 according to Example 2. Table 10 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 2 according to Example 2.

[0079] The imaging optical system 2 according to Example 2 includes, in order from the object side to the image plane side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. An aperture stop St is located within the first lens group G1.

[0080] The first lens group G1 has positive refractive power. The first lens group G1 is composed of, in order from the object side to the image side, lenses L1 to L7 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side of the first lens group G1 has negative refractive power. The first lens group G1 has an aspherical lens (lens L7) closest to the image side.

[0081] In the first lens group G1, lens L1 is a negative meniscus lens with a convex surface facing the object side. Lens L2 is a negative meniscus lens with a convex surface facing the object side. Lens L3 is a negative biconcave lens. Lens L4 is a positive biconvex lens. Lens L5 is a negative biconcave lens. Lens L6 is a positive biconvex lens. Lens L7 is a positive biconvex lens. Lens L2 and lens L7 are each an aspherical lens with aspherical surfaces formed on both sides. Lenses L3 and L4 are cemented together to form a cemented lens. Lenses L5 and L6 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of seven lenses and five lens components.

[0082] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L8 to L14. The second lens group G2 has a positive lens (lens L12) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L14) closest to the image surface. The second lens group G2 has a cemented lens.

[0083] In the second lens group G2, lens L8 is a biconvex positive lens. Lens L9 is a positive meniscus lens with a concave surface facing the object side. Lens L10 is a biconcave negative lens. Lens L11 is a negative meniscus lens with a concave surface facing the object side. Lens L12 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L13 is a biconvex positive lens. Lens L14 is a negative meniscus lens with a concave surface facing the object side. Lens L14 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L9 and L10 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of seven lenses and six lens components.

[0084] The third lens group G3 has negative refractive power. The third lens group G3 is made up of the lens L15. The lens L15 is a negative biconcave lens. As described above, the third lens group G3 is made up of one lens, one lens component.

[0085] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L8 and the distance between the lenses L14 and L15 change.

[0086] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0087]

[0088]

[0089]

[0090]

[0091]

[0092] Fig. 7 shows longitudinal aberration when the imaging optical system 2 according to Example 2 is focused at infinity. Fig. 8 shows longitudinal aberration when the imaging optical system 2 according to Example 2 is focused at a close distance. Fig. 9 shows lateral aberration when the imaging optical system 2 according to Example 2 is focused at infinity. Fig. 10 shows lateral aberration when the imaging optical system 2 according to Example 2 is focused at a close distance.

[0093] As can be seen from each aberration diagram, the imaging optical system 2 according to Example 2 has excellent correction of various aberrations and has excellent imaging performance.

[0094] Example 3 Table 11 shows basic lens data for the imaging optical system 3 according to Example 3 shown in FIG. 11 . Table 12 shows the values ​​of the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 3 according to Example 3. Table 13 shows data on surface spacings that are variable during focusing in the imaging optical system 3 according to Example 3. Table 12 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 13 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 14 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 3 according to Example 3. Table 15 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 3 according to Example 3.

[0095] The imaging optical system 3 according to Example 3 includes, in order from the object side to the image plane side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. An aperture stop St is located within the first lens group G1.

[0096] The first lens group G1 has positive refractive power. The first lens group G1 is composed of, in order from the object side to the image side, lenses L1 to L5 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side of the first lens group G1 has negative refractive power. The first lens group G1 has an aspherical lens (lens L5) closest to the image side.

[0097] In the first lens group G1, lens L1 is a negative meniscus lens with its convex surface facing the object side. Lens L2 is a negative biconcave lens. Lens L3 is a positive biconvex lens. Lens L4 is a negative biconcave lens. Lens L5 is a positive biconvex lens. Lenses L1 and L5 are each an aspherical lens with aspherical surfaces formed on both sides. Lenses L2 and L3 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of five lenses and four lens components.

[0098] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L6 to L10. The second lens group G2 has a positive lens (lens L9) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L10) closest to the image surface. The second lens group G2 has a cemented lens.

[0099] In the second lens group G2, lens L6 is a biconvex positive lens. Lens L7 is a biconcave negative lens. Lens L8 is a negative meniscus lens with its concave surface facing the object side. Lens L9 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L10 is a positive meniscus lens with its convex surface facing the object side. Lens L10 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L6 and L7 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of five lenses and four lens components.

[0100] The third lens group G3 has negative refractive power. The third lens group G3 is made up of the lens L11. The lens L11 is a negative biconcave lens. As described above, the third lens group G3 is made up of one lens, one lens component.

[0101] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L6 and the distance between the lenses L10 and L11 change.

[0102] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0103]

[0104]

[0105]

[0106]

[0107]

[0108] Fig. 12 shows longitudinal aberration when the imaging optical system 3 according to Example 3 is focused at infinity. Fig. 13 shows longitudinal aberration when the imaging optical system 3 according to Example 3 is focused at a close distance. Fig. 14 shows lateral aberration when the imaging optical system 3 according to Example 3 is focused at infinity. Fig. 15 shows lateral aberration when the imaging optical system 3 according to Example 3 is focused at a close distance.

[0109] As can be seen from each aberration diagram, the imaging optical system 3 according to Example 3 has excellent imaging performance with various aberrations corrected well.

[0110] Example 4 Table 16 shows basic lens data for the imaging optical system 4 according to Example 4 shown in FIG. 16 . Table 17 shows the values ​​of the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 4 according to Example 4. Table 18 shows data on surface spacings that are variable during focusing in the imaging optical system 4 according to Example 4. Table 17 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 18 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 19 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 4 according to Example 4. Table 20 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 4 according to Example 4.

[0111] The imaging optical system 4 according to Example 4 includes, in order from the object side to the image plane side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. An aperture stop St is disposed within the first lens group G1.

[0112] The first lens group G1 has negative refractive power. The first lens group G1 is composed of, in order from the object side to the image side, lenses L1 to L7 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side of the first lens group G1 has negative refractive power. The first lens group G1 has an aspherical lens (lens L7) closest to the image side.

[0113] In the first lens group G1, lens L1 is a negative meniscus lens with a convex surface facing the object side. Lens L2 is a negative meniscus lens with a convex surface facing the object side. Lens L3 is a negative biconcave lens. Lens L4 is a positive biconvex lens. Lens L5 is a negative biconcave lens. Lens L6 is a positive biconvex lens. Lens L7 is a positive meniscus lens with a convex surface facing the object side. Lenses L2 and L7 are each an aspherical lens with aspherical surfaces formed on both sides. Lenses L3 and L4 are cemented together to form a cemented lens. Lenses L5 and L6 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of seven lenses and five lens components.

[0114] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L8 to L14. The second lens group G2 has a positive lens (lens L12) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L14) closest to the image surface. The second lens group G2 has a cemented lens.

[0115] In the second lens group G2, lens L8 is a biconvex positive lens. Lens L9 is a biconvex positive lens. Lens L10 is a biconcave negative lens. Lens L11 is a negative meniscus lens with its concave surface facing the object side. Lens L12 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L13 is a positive meniscus lens with its concave surface facing the object side. Lens L14 is a biconcave negative lens. Lens L14 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L9 and L10 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of seven lenses and six lens components.

[0116] The third lens group G3 has negative refractive power and is made up of the lens L15. The lens L15 is a negative meniscus lens with its convex surface facing the object side. As described above, the third lens group G3 is made up of one lens and one lens component.

[0117] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L8 and the distance between the lenses L14 and L15 change.

[0118] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] Fig. 17 shows longitudinal aberration when the imaging optical system 4 according to Example 4 is focused at infinity. Fig. 18 shows longitudinal aberration when the imaging optical system 4 according to Example 4 is focused at a close distance. Fig. 19 shows lateral aberration when the imaging optical system 4 according to Example 4 is focused at infinity. Fig. 20 shows lateral aberration when the imaging optical system 4 according to Example 4 is focused at a close distance.

[0125] As can be seen from each aberration diagram, the imaging optical system 4 according to Example 4 has excellent correction of various aberrations and has excellent imaging performance.

[0126] [Example 5] Table 21 shows basic lens data for the imaging optical system 5 according to Example 5 shown in FIG. 21 . Table 22 shows the values ​​of the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 5 according to Example 5. Table 23 shows data on surface spacings that are variable during focusing in the imaging optical system 5 according to Example 5. Table 22 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 23 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 24 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 5 according to Example 5. Table 25 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 5 according to Example 5.

[0127] The imaging optical system 5 according to Example 5 includes, in order from the object side to the image plane side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. An aperture stop St is located within the first lens group G1.

[0128] The first lens group G1 has positive refractive power. The first lens group G1 is composed of, in order from the object side to the image plane side, lenses L1 to L5 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side in the first lens group G1 has negative refractive power.

[0129] In the first lens group G1, lens L1 is a negative meniscus lens with a convex surface facing the object side. Lens L2 is a negative biconcave lens. Lens L3 is a positive biconvex lens. Lens L4 is a positive biconvex lens. Lens L5 is a negative meniscus lens with a concave surface facing the object side. Lenses L1 and L4 are each an aspherical lens with an aspherical surface formed on one side. Lenses L2 and L3 are cemented together to form a cemented lens. Lenses L4 and L5 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of five lenses and three lens components.

[0130] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L6 to L11. The second lens group G2 has a positive lens (lens L10) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L11) closest to the image surface. The second lens group G2 has a cemented lens.

[0131] In the second lens group G2, lens L6 is a biconvex positive lens. Lens L7 is a biconcave negative lens. Lens L8 is a negative meniscus lens with its concave surface facing the object side. Lens L9 is a biconvex positive lens. Lens L10 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L11 is a biconcave negative lens. Lens L11 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L6 and L7 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of six lenses and five lens components.

[0132] The third lens group G3 has negative refractive power. The third lens group G3 is made up of the lens L12. The lens L12 is a negative biconcave lens. As described above, the third lens group G3 is made up of one lens, one lens component.

[0133] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L6 and the distance between the lenses L11 and L12 change.

[0134] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0135]

[0136]

[0137]

[0138]

[0139]

[0140] Fig. 22 shows longitudinal aberration of the imaging optical system 5 according to Example 5 at the wide-angle end and when focusing on infinity. Fig. 23 shows longitudinal aberration when focusing on a close distance. Fig. 24 shows lateral aberration of the imaging optical system 5 according to Example 5 when focusing on infinity. Fig. 25 shows lateral aberration of the imaging optical system 5 according to Example 5 when focusing on a close distance.

[0141] As can be seen from each aberration diagram, the imaging optical system 5 according to Example 5 has excellent imaging performance with various aberrations corrected well.

[0142] Example 6 Table 26 shows basic lens data for the imaging optical system 6 according to Example 6 shown in FIG. 26 . Table 27 shows the values ​​of the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 6 according to Example 6. Table 28 shows data on surface spacings that are variable during focusing in the imaging optical system 6 according to Example 6. Table 27 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 28 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 29 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 6 according to Example 6. Table 30 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 6 according to Example 6.

[0143] The imaging optical system 6 according to Example 6 includes, in order from the object side to the image plane side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. An aperture stop St is located within the first lens group G1.

[0144] The first lens group G1 has positive refractive power. The first lens group G1 is composed of, in order from the object side to the image side, lenses L1 to L5 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side of the first lens group G1 has negative refractive power. The first lens group G1 has an aspherical lens (lens L5) closest to the image side.

[0145] In the first lens group G1, lens L1 is a negative meniscus lens with a convex surface facing the object side. Lens L2 is a negative biconcave lens. Lens L3 is a positive biconvex lens. Lens L4 is a negative meniscus lens with a concave surface facing the object side. Lens L5 is a positive biconvex lens. Lenses L1 and L5 are each an aspherical lens with aspherical surfaces formed on both sides. Lenses L2 and L3 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of five lenses and four lens components.

[0146] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L6 to L10. The second lens group G2 has a positive lens (lens L9) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L10) closest to the image surface. The second lens group G2 has a cemented lens.

[0147] In the second lens group G2, lens L6 is a biconvex positive lens. Lens L7 is a negative meniscus lens with its concave surface facing the object side. Lens L8 is a biconcave negative lens. Lens L9 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L10 is a biconvex positive lens. Lens L10 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L6 and L7 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of five lenses and four lens components.

[0148] The third lens group G3 has negative refractive power. The third lens group G3 is composed of, in order from the object side to the image plane side, a lens L11 and a lens L12. The lens L11 is a positive biconvex lens. The lens L12 is a negative biconcave lens. The lenses L11 and L12 are cemented together to form a cemented lens. As described above, the third lens group G3 is composed of two lenses, or one lens component.

[0149] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L6 and the distance between the lenses L10 and L11 change.

[0150] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0151]

[0152]

[0153]

[0154]

[0155]

[0156] Fig. 27 shows longitudinal aberration of the imaging optical system 6 according to Example 6 at the wide-angle end and when focused on infinity. Fig. 28 shows longitudinal aberration when focused on a close distance. Fig. 29 shows lateral aberration of the imaging optical system 6 according to Example 6 when focused on infinity. Fig. 30 shows lateral aberration of the imaging optical system 6 according to Example 6 when focused on a close distance.

[0157] As can be seen from each aberration diagram, the imaging optical system 6 according to Example 6 has excellent correction of various aberrations and has excellent imaging performance.

[0158] Example 7 Table 31 shows basic lens data for the imaging optical system 7 according to Example 7 shown in FIG. 31 . Table 32 shows the values ​​of the focal length f, F-number, total angle of view 2ω, image height Y, and total optical length L of the entire system in the imaging optical system 7 according to Example 7. Table 33 shows data on surface spacings that are variable during focusing in the imaging optical system 7 according to Example 7. Table 32 shows values ​​when the shooting distance and object distance (d0) are infinity. Table 33 shows values ​​when the shooting distance and object distance (d0) are infinity and when they are close. Table 34 shows values ​​of coefficients that represent the shape of the aspherical surface in the imaging optical system 7 according to Example 7. Table 35 shows the first surface and focal length (unit: mm) of each lens group in the imaging optical system 7 according to Example 7.

[0159] The imaging optical system 7 according to Example 7 includes, in order from the object side to the image plane side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. An aperture stop St is located within the first lens group G1.

[0160] The first lens group G1 has positive refractive power. The first lens group G1 is composed of, in order from the object side to the image side, lenses L1 to L7 and an aperture stop St. The first lens group G1 has a negative lens (lens L1) closest to the object side. The second lens L2 from the object side of the first lens group G1 has negative refractive power. The first lens group G1 has an aspherical lens (lens L7) closest to the image side.

[0161] In the first lens group G1, lens L1 is a negative meniscus lens with a convex surface facing the object side. Lens L2 is a negative meniscus lens with a convex surface facing the object side. Lens L3 is a negative biconcave lens. Lens L4 is a positive biconvex lens. Lens L5 is a negative biconcave lens. Lens L6 is a positive meniscus lens with a convex surface facing the object side. Lens L7 is a positive biconvex lens. Lenses L2 and L7 are each an aspherical lens with aspherical surfaces formed on both sides. Lenses L3 and L4 are cemented together to form a cemented lens. Lenses L5 and L6 are cemented together to form a cemented lens. As described above, the first lens group G1 is composed of seven lenses and five lens components.

[0162] The second lens group G2 has positive refractive power. The second lens group G2 is composed of, in order from the object side to the image surface side, lenses L8 to L12. The second lens group G2 has a positive lens (lens L10) that satisfies the above conditional expressions (2) and (3). The second lens group G2 has an aspherical lens (lens L12) closest to the image surface. The second lens group G2 has a cemented lens.

[0163] In the second lens group G2, lens L8 is a biconvex positive lens. Lens L9 is a biconcave negative lens. Lens L10 is a biconvex positive lens that satisfies the above conditional expressions (2) and (3). Lens L11 is a positive meniscus lens with its concave surface facing the object side. Lens L12 is a negative meniscus lens with its convex surface facing the object side. Lens L12 is an aspherical lens with aspherical surfaces formed on both sides. Lenses L8 and L9 are cemented together to form a cemented lens. As described above, the second lens group G2 is composed of five lenses and four lens components.

[0164] The third lens group G3 has negative refractive power and is made up of the lens L13. The lens L13 is a negative meniscus lens with its convex surface facing the object side. As described above, the third lens group G3 is made up of one lens and one lens component.

[0165] During focusing from infinity to a close distance, the first lens group G1 and the third lens group G3 are fixed relative to the image plane, and the entire second lens group G2 moves parallel to the optical axis toward the object. During focusing, the distance between the aperture stop St and the lens L8 and the distance between the lens L12 and the lens L13 change.

[0166] The above configuration achieves a compact, lightweight lens and high image quality while suppressing fluctuations in the angle of view that occur during focusing.

[0167]

[0168]

[0169]

[0170]

[0171]

[0172] Fig. 32 shows longitudinal aberration of the imaging optical system 7 according to Example 7 at the wide-angle end and when focused on infinity. Fig. 33 shows longitudinal aberration when focused on a close distance. Fig. 34 shows lateral aberration of the imaging optical system 7 according to Example 7 when focused on infinity. Fig. 35 shows lateral aberration of the imaging optical system 7 according to Example 7 when focused on a close distance.

[0173] As can be seen from each aberration diagram, the imaging optical system 7 according to Example 7 has excellent correction of various aberrations and has excellent imaging performance.

[0174] [Other Numerical Data for Each Example] [Table 36] shows a summary of the parameter values ​​constituting each of the above-mentioned conditional expressions for each Example. As can be seen from [Table 36], for each conditional expression, the values ​​for each Example are within the numerical ranges specified for the expressions, except for Example 7. For Example 7, all values ​​except for Conditional Expressions (4) and (6) are within the numerical ranges specified for the expressions.

[0175]

[0176] 5. Application Examples 5.1 First Application Example The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, construction machinery, or agricultural machinery (tractor).

[0177] 37 is a block diagram showing a schematic configuration example of a vehicle control system 7000, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied. The vehicle control system 7000 includes a plurality of electronic control units connected via a communication network 7010. In the example shown in FIG. 37 , the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an outside-vehicle information detection unit 7400, an inside-vehicle information detection unit 7500, and an integrated control unit 7600. The communication network 7010 connecting these multiple control units may be an in-vehicle communication network conforming to any standard, such as a Controller Area Network (CAN), a Local Interconnect Network (LIN), a Local Area Network (LAN), or FlexRay (registered trademark).

[0178] Each control unit includes a microcomputer that performs arithmetic processing according to various programs, a memory unit that stores the programs executed by the microcomputer or parameters used in various calculations, and a drive circuit that drives various controlled devices. Each control unit includes a network I / F for communicating with other control units via a communication network 7010, and a communication I / F for communicating with devices or sensors inside and outside the vehicle via wired or wireless communication. Figure 37 illustrates the functional configuration of the integrated control unit 7600, including a microcomputer 7610, a general-purpose communication I / F 7620, a dedicated communication I / F 7630, a positioning unit 7640, a beacon receiving unit 7650, an in-vehicle device I / F 7660, an audio / video output unit 7670, an in-vehicle network I / F 7680, and a memory unit 7690. Other control units also include a microcomputer, a communication I / F, a memory unit, and the like.

[0179] The drivetrain control unit 7100 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 7100 functions as a control device for a drive force generating device for generating drive force for the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating braking force for the vehicle. The drivetrain control unit 7100 may also function as a control device for an ABS (Antilock Brake System) or an ESC (Electronic Stability Control), etc.

[0180] A vehicle state detection unit 7110 is connected to the drivetrain control unit 7100. The vehicle state detection unit 7110 includes at least one of a gyro sensor that detects the angular velocity of the axial rotational motion of the vehicle body, an acceleration sensor that detects the acceleration of the vehicle, or a sensor that detects the amount of operation of the accelerator pedal, the amount of operation of the brake pedal, the steering angle of the steering wheel, the engine rotation speed, the rotation speed of the wheels, etc. The drivetrain control unit 7100 performs arithmetic processing using signals input from the vehicle state detection unit 7110, and controls the internal combustion engine, the drive motor, the electric power steering device, the brake device, etc.

[0181] The body system control unit 7200 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 7200 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 7200. The body system control unit 7200 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0182] The battery control unit 7300 controls the secondary battery 7310, which is the power supply source for the drive motor, in accordance with various programs. For example, information such as battery temperature, battery output voltage, or remaining battery capacity is input to the battery control unit 7300 from a battery device equipped with the secondary battery 7310. The battery control unit 7300 performs arithmetic processing using these signals, and controls the temperature regulation of the secondary battery 7310 or a cooling device or the like equipped in the battery device.

[0183] The outside vehicle information detection unit 7400 detects information outside the vehicle equipped with the vehicle control system 7000. For example, at least one of an imaging unit 7410 and an outside vehicle information detection unit 7420 is connected to the outside vehicle information detection unit 7400. The imaging unit 7410 includes at least one of a time-of-flight (ToF) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The outside vehicle information detection unit 7420 includes at least one of an environmental sensor for detecting the current weather or climate, or a surrounding information detection sensor for detecting other vehicles, obstacles, pedestrians, etc. around the vehicle equipped with the vehicle control system 7000.

[0184] The environmental sensor may be, for example, at least one of a raindrop sensor that detects rain, a fog sensor that detects fog, a sunshine sensor that detects the degree of sunshine, and a snow sensor that detects snowfall. The surrounding information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. The imaging unit 7410 and the outside vehicle information detection unit 7420 may each be provided as an independent sensor or device, or may be provided as a device in which multiple sensors or devices are integrated.

[0185] Here, Figure 38 shows an example of the installation positions of the imaging unit 7410 and the vehicle exterior information detection unit 7420. The imaging units 7910, 7912, 7914, 7916, and 7918 are provided, for example, at least one of the front nose, side mirrors, rear bumper, back door, and upper part of the windshield inside the vehicle cabin of the vehicle 7900. The imaging unit 7910 provided on the front nose and the imaging unit 7918 provided on the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 7900. The imaging units 7912 and 7914 provided on the side mirrors mainly acquire images of the sides of the vehicle 7900. The imaging unit 7916 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 7900. The imaging unit 7918 provided on the upper part of the windshield inside the vehicle cabin is mainly used to detect leading vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0186] 38 shows an example of the imaging ranges of the imaging units 7910, 7912, 7914, and 7916. Imaging range a indicates the imaging range of the imaging unit 7910 provided on the front nose, imaging ranges b and c indicate the imaging ranges of the imaging units 7912 and 7914 provided on the side mirrors, respectively, and imaging range d indicates the imaging range of the imaging unit 7916 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 7910, 7912, 7914, and 7916, a bird's-eye view image of the vehicle 7900 viewed from above can be obtained.

[0187] The outside vehicle information detection units 7920, 7922, 7924, 7926, 7928, and 7930 provided on the front, rear, sides, corners, and above the windshield inside the vehicle cabin of the vehicle 7900 may be, for example, ultrasonic sensors or radar devices. The outside vehicle information detection units 7920, 7926, and 7930 provided on the front nose, rear bumper, back door, and above the windshield inside the vehicle cabin of the vehicle 7900 may be, for example, LIDAR devices. These outside vehicle information detection units 7920 to 7930 are mainly used to detect preceding vehicles, pedestrians, obstacles, etc.

[0188] Returning to FIG. 37 , the explanation continues. The outside-vehicle information detection unit 7400 causes the imaging unit 7410 to capture an image outside the vehicle and receives the captured image data. The outside-vehicle information detection unit 7400 also receives detection information from the connected outside-vehicle information detection unit 7420. If the outside-vehicle information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the outside-vehicle information detection unit 7400 emits ultrasonic waves or electromagnetic waves and receives information on the received reflected waves. Based on the received information, the outside-vehicle information detection unit 7400 may perform object detection processing or distance detection processing for people, vehicles, obstacles, signs, text on the road, etc. Based on the received information, the outside-vehicle information detection unit 7400 may also perform environmental recognition processing for recognizing rainfall, fog, road conditions, etc. Based on the received information, the outside-vehicle information detection unit 7400 may also calculate the distance to an object outside the vehicle.

[0189] The outside vehicle information detection unit 7400 may also perform image recognition processing or distance detection processing to recognize people, vehicles, obstacles, signs, or characters on the road surface based on the received image data. The outside vehicle information detection unit 7400 may perform processing such as distortion correction or alignment on the received image data, and may also generate an overhead image or a panoramic image by combining image data captured by different image capturing units 7410. The outside vehicle information detection unit 7400 may also perform viewpoint conversion processing using image data captured by different image capturing units 7410.

[0190] The interior information detection unit 7500 detects information inside the vehicle. A driver state detection unit 7510 that detects the driver's state is connected to the interior information detection unit 7500, for example. The driver state detection unit 7510 may include a camera that captures an image of the driver, a biosensor that detects the driver's biometric information, or a microphone that collects sound from within the vehicle cabin. The biosensor is provided, for example, on the seat or steering wheel, and detects the biometric information of a passenger sitting in the seat or the driver gripping the steering wheel. The interior information detection unit 7500 may calculate the driver's level of fatigue or concentration based on the detection information input from the driver state detection unit 7510, or may determine whether the driver is dozing off. The interior information detection unit 7500 may perform processing such as noise canceling on the collected audio signal.

[0191] The integrated control unit 7600 controls the overall operation of the vehicle control system 7000 according to various programs. An input unit 7800 is connected to the integrated control unit 7600. The input unit 7800 may be implemented by a device that can be operated by a passenger, such as a touch panel, a button, a microphone, a switch, or a lever. Data obtained by voice recognition of a voice input through a microphone may be input to the integrated control unit 7600. The input unit 7800 may be, for example, a remote control device using infrared or other radio waves, or an externally connected device such as a mobile phone or a personal digital assistant (PDA) that can operate the vehicle control system 7000. The input unit 7800 may be, for example, a camera, in which case the passenger can input information using gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by the passenger may be input. Furthermore, the input unit 7800 may include, for example, an input control circuit that generates an input signal based on information input by the passenger using the input unit 7800 and outputs the input signal to the integrated control unit 7600. Passengers and the like operate this input unit 7800 to input various data to the vehicle control system 7000 and to instruct processing operations.

[0192] The storage unit 7690 may include a ROM (Read Only Memory) that stores various programs executed by the microcomputer, and a RAM (Random Access Memory) that stores various parameters, calculation results, sensor values, etc. The storage unit 7690 may also be realized by a magnetic storage device such as an HDD (Hard Disc Drive), a semiconductor storage device, an optical storage device, a magneto-optical storage device, or the like.

[0193] The general-purpose communication I / F 7620 is a general-purpose communication I / F that mediates communication with various devices present in the external environment 7750. The general-purpose communication I / F 7620 may implement a cellular communication protocol such as GSM (Global System of Mobile communications), WiMAX (registered trademark), LTE (Long Term Evolution), or LTE-Advanced (LTE-A), or other wireless communication protocols such as a wireless LAN (also referred to as Wi-Fi (registered trademark)) or Bluetooth (registered trademark). The general-purpose communication I / F 7620 may connect to a device (e.g., an application server or a control server) present on an external network (e.g., the Internet, a cloud network, or an operator-specific network) via, for example, a base station or an access point. In addition, the general-purpose communication I / F 7620 may connect to a terminal located near the vehicle (for example, a terminal of a driver, pedestrian, or store, or an MTC (Machine Type Communication) terminal) using, for example, P2P (Peer To Peer) technology.

[0194] The dedicated communication I / F 7630 is a communication I / F that supports a communication protocol designed for use in vehicles. The dedicated communication I / F 7630 may implement a standard protocol such as WAVE (Wireless Access in Vehicle Environment), which is a combination of a lower layer IEEE 802.11p and an upper layer IEEE 1609, DSRC (Dedicated Short Range Communications), or a cellular communication protocol. The dedicated communication I / F 7630 typically performs V2X communication, which is a concept including one or more of vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication.

[0195] The positioning unit 7640 performs positioning by receiving, for example, GNSS signals from GNSS (Global Navigation Satellite System) satellites (for example, GPS signals from GPS (Global Positioning System) satellites), and generates position information including the latitude, longitude, and altitude of the vehicle. Note that the positioning unit 7640 may identify the current position by exchanging signals with a wireless access point, or may obtain position information from a terminal such as a mobile phone, PHS, or smartphone that has a positioning function.

[0196] The beacon receiving unit 7650 receives, for example, radio waves or electromagnetic waves transmitted from radio stations or the like installed on the road, and acquires information such as the current location, congestion, road closures, required travel time, etc. The function of the beacon receiving unit 7650 may be included in the dedicated communication I / F 7630 described above.

[0197] The in-vehicle device I / F 7660 is a communication interface that mediates connections between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I / F 7660 may establish a wireless connection using a wireless communication protocol such as a wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), or WUSB (Wireless USB). The in-vehicle device I / F 7660 may also establish a wired connection via a connection terminal (and, if necessary, a cable) not shown, such as a Universal Serial Bus (USB), a High-Definition Multimedia Interface (HDMI (registered trademark), or an MHL (Mobile High-Definition Link)). The in-vehicle device 7760 may include, for example, at least one of a mobile device or wearable device owned by a passenger, or an information device carried or installed in the vehicle. The in-vehicle device 7760 may also include a navigation device that searches for a route to a desired destination. The in-vehicle device I / F 7660 exchanges control signals or data signals with these in-vehicle devices 7760 .

[0198] The in-vehicle network I / F 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I / F 7680 transmits and receives signals in accordance with a predetermined protocol supported by the communication network 7010.

[0199] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 in accordance with various programs based on information acquired via at least one of the general-purpose communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the in-vehicle device I / F 7660, and the in-vehicle network I / F 7680. For example, the microcomputer 7610 may calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the acquired information inside and outside the vehicle, and output control commands to the drivetrain control unit 7100. For example, the microcomputer 7610 may perform cooperative control aimed at realizing functions of an Advanced Driver Assistance System (ADAS), including vehicle collision avoidance or impact mitigation, following driving based on the following distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc. In addition, the microcomputer 7610 may perform cooperative control for the purpose of autonomous driving, in which the vehicle travels autonomously without relying on driver operation, by controlling a driving force generating device, a steering mechanism, a braking device, etc. based on information acquired about the vehicle's surroundings.

[0200] The microcomputer 7610 may generate three-dimensional distance information between the vehicle and objects such as surrounding structures and people, and create local map information including information about the vicinity of the vehicle's current location, based on information acquired via at least one of the general-purpose communication I / F 7620, the dedicated communication I / F 7630, the positioning unit 7640, the beacon receiving unit 7650, the in-vehicle device I / F 7660, and the in-vehicle network I / F 7680. Furthermore, the microcomputer 7610 may predict dangers, such as a vehicle collision, the approach of a pedestrian, or entry into a closed road, based on the acquired information, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or turning on a warning lamp.

[0201] The audio / image output unit 7670 transmits at least one audio and / or image output signal to an output device capable of visually or audibly notifying vehicle occupants or the outside of the vehicle of information. In the example of FIG. 37 , an audio speaker 7710, a display unit 7720, and an instrument panel 7730 are illustrated as output devices. The display unit 7720 may include, for example, at least one of an on-board display and a head-up display. The display unit 7720 may have an AR (Augmented Reality) display function. The output device may also be other devices, such as headphones, a wearable device such as an eyeglass-type display worn by the occupant, a projector, or a lamp. When the output device is a display device, the display device visually displays results obtained by various processes performed by the microcomputer 7610 or information received from other control units in various formats, such as text, images, tables, and graphs. When the output device is an audio output device, the audio output device converts audio signals, such as reproduced audio data or acoustic data, into analog signals and audibly outputs the analog signals.

[0202] In the example shown in FIG. 37 , at least two control units connected via the communication network 7010 may be integrated into a single control unit. Alternatively, each control unit may be composed of multiple control units. Furthermore, the vehicle control system 7000 may include another control unit not shown. In the above description, some or all of the functions performed by one of the control units may be assigned to another control unit. In other words, as long as information is transmitted and received via the communication network 7010, predetermined arithmetic processing may be performed by one of the control units. Similarly, a sensor or device connected to one of the control units may be connected to another control unit, and multiple control units may transmit and receive detection information to each other via the communication network 7010.

[0203] In the vehicle control system 7000 described above, the imaging optical system and imaging device of the present disclosure can be applied to the imaging unit 7410 and the imaging units 7910, 7912, 7914, 7916, and 7918.

[0204] 5.2 Second Application Example The technology according to the present disclosure can be applied to a medical imaging system, which is a medical system that uses imaging technology, such as an endoscope system or a microscope system.

[0205] [Endoscopic System] An example of an endoscope system will be described with reference to FIGS. 39 and 40 . FIG. 39 is a diagram illustrating an example of the schematic configuration of an endoscope system 5000 to which the technology according to the present disclosure can be applied. FIG. 40 is a diagram illustrating an example of the configuration of an endoscope 5001 and a CCU (Camera Control Unit) 5039. FIG. 39 illustrates a state in which an operator (e.g., a doctor) 5067, who is a surgical participant, is performing surgery on a patient 5071 on a patient bed 5069 using the endoscope system 5000. As shown in FIG. 39 , the endoscope system 5000 includes an endoscope 5001, which is a medical imaging device, a CCU 5039, a light source device 5043, a recording device 5053, an output device 5055, and a support device 5027 that supports the endoscope 5001.

[0206] In endoscopic surgery, an insertion aid called a trocar 5025 is inserted into a patient 5071. Then, a scope 5003 and surgical tools 5021 connected to an endoscope 5001 are inserted into the body of the patient 5071 via the trocar 5025. The surgical tools 5021 are, for example, energy devices such as an electric scalpel, forceps, etc.

[0207] A surgical image, which is a medical image showing the inside of the body of a patient 5071 photographed by an endoscope 5001, is displayed on a display device 5041. An operator 5067 performs a procedure on the surgical target using a surgical tool 5021 while viewing the surgical image displayed on the display device 5041. Note that the medical image is not limited to a surgical image, and may be a diagnostic image photographed during a diagnosis.

[0208] [Endoscope] The endoscope 5001 is an imaging unit that captures images of the inside of the patient's 5071. For example, as shown in FIG. 40 , the endoscope 5001 is a camera 5005 that includes a focusing optical system 50051 that focuses incident light, a zoom optical system 50052 that changes the focal length of the imaging unit to enable optical zoom, a focus optical system 50053 that changes the focal length of the imaging unit to enable focus adjustment, and a light-receiving element 50054. The endoscope 5001 generates pixel signals by focusing light onto the light-receiving element 50054 via a connected scope 5003, and outputs the pixel signals to the CCU 5039 via a transmission system. The scope 5003 has an objective lens at its tip and is an insertion section that guides light from a connected light source device 5043 into the inside of the patient's 5071. The scope 5003 is, for example, a rigid scope for rigid endoscopes or a flexible scope for flexible endoscopes. The scope 5003 may be a direct-view endoscope or an oblique-view endoscope. Furthermore, the pixel signal may be a signal based on a signal output from a pixel, such as a RAW signal or an image signal. Furthermore, a configuration may be adopted in which a memory is installed in the transmission system connecting the endoscope 5001 and the CCU 5039, and parameters related to the endoscope 5001 and the CCU 5039 are stored in the memory. The memory may be located, for example, in a connection portion of the transmission system or on a cable. For example, parameters at the time of shipment of the endoscope 5001 and parameters that change when power is applied may be stored in the memory of the transmission system, and the operation of the endoscope may be changed based on parameters read from the memory. Furthermore, the endoscope and the transmission system may be collectively referred to as an endoscope. The light-receiving element 50054 is a sensor that converts received light into a pixel signal, and is, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. It is preferable that the light-receiving element 50054 be an image sensor capable of color imaging with a Bayer array. Furthermore, the light receiving element 50054 is preferably an imaging element having a number of pixels corresponding to a resolution of, for example, 4K (3840 horizontal pixels × 2160 vertical pixels), 8K (7680 horizontal pixels × 4320 vertical pixels), or square 4K (3840 or more horizontal pixels × 3840 or more vertical pixels). The light receiving element 50054 may be a single sensor chip or multiple sensor chips.For example, a prism may be provided to separate incident light into predetermined wavelength bands, and each wavelength band may be imaged by a different light-receiving element. Alternatively, multiple light-receiving elements may be provided for stereoscopic vision. The light-receiving element 50054 may be a sensor including an image processing circuit within its chip structure, or a Time of Flight (ToF) sensor. The transmission system may be, for example, an optical fiber cable or wireless transmission. Wireless transmission may be performed via any means capable of transmitting pixel signals generated by the endoscope 5001. For example, the endoscope 5001 and the CCU 5039 may be connected wirelessly, or the endoscope 5001 and the CCU 5039 may be connected via a base station in the operating room. In this case, the endoscope 5001 may simultaneously transmit not only pixel signals but also information related to the pixel signals (e.g., pixel signal processing priority, synchronization signal, etc.). The endoscope may be configured such that the scope and camera are integrated, or a light-receiving element is provided at the tip of the scope.

[0209] [CCU (Camera Control Unit)] The CCU 5039 is a control device that comprehensively controls the connected endoscope 5001 and light source device 5043. For example, as shown in FIG. 40 , the CCU 5039 is an information processing device having an FPGA 50391, a CPU 50392, a RAM 50393, a ROM 50394, a GPU 50395, and an I / F 50396. The CCU 5039 may also comprehensively control the connected display device 5041, recording device 5053, and output device 5055. For example, the CCU 5039 controls the irradiation timing, irradiation intensity, and type of irradiation light source of the light source device 5043. The CCU 5039 also performs image processing such as development processing (e.g., demosaic processing) and correction processing on pixel signals output from the endoscope 5001, and outputs the processed pixel signals (e.g., an image) to an external device such as the display device 5041. Furthermore, the CCU 5039 transmits a control signal to the endoscope 5001 to control the driving of the endoscope 5001. The control signal is, for example, information regarding imaging conditions such as the magnification and focal length of the imaging unit. The CCU 5039 may have an image down-conversion function and be configured to be able to simultaneously output a high-resolution (e.g., 4K) image to the display device 5041 and a low-resolution (e.g., HD) image to the recording device 5053.

[0210] The CCU 5039 may also be connected to external devices (e.g., recording devices, display devices, output devices, and support devices) via an IP converter that converts signals into a predetermined communication protocol (e.g., IP (Internet Protocol)). The connection between the IP converter and the external devices may be configured as a wired network, or a partial or entire network may be configured as a wireless network. For example, the IP converter on the CCU 5039 side may have a wireless communication function and transmit the received video to an IP switcher or an output-side IP converter via a wireless communication network such as a fifth-generation mobile communication system (5G) or a sixth-generation mobile communication system (6G).

[0211] [Light Source Device] The light source device 5043 is a device capable of emitting light in a predetermined wavelength band and includes, for example, multiple light sources and a light source optical system that guides the light from the multiple light sources. The light sources are, for example, a xenon lamp, an LED light source, or an LD light source. The light source device 5043 has, for example, LED light sources corresponding to the three primary colors R, G, and B, and emits white light by controlling the output intensity and output timing of each light source. Furthermore, the light source device 5043 may include a light source that can emit special light used for special light observation, in addition to a light source that emits normal light used for normal light observation. The special light is light in a predetermined wavelength band different from the normal light used for normal light observation, such as near-infrared light (light with a wavelength of 760 nm or more), infrared light, blue light, or ultraviolet light. The normal light is, for example, white light or green light. Narrowband light observation, a type of special light observation, alternately emits blue light and green light to utilize the wavelength-dependence of light absorption in body tissue, enabling high-contrast imaging of specific tissue, such as blood vessels on the surface of the mucous membrane. Furthermore, in fluorescence observation, a type of special light observation, excitation light is applied to excite a drug injected into the body tissue, and fluorescence emitted by the drug as a marker is received to obtain a fluorescence image, thereby making it easier for the surgeon to visualize body tissues that are difficult for the surgeon to see under normal light. For example, in fluorescence observation using infrared light, infrared light having an excitation wavelength band is applied to a drug such as indocyanine green (ICG) injected into the body tissue, and the fluorescence of the drug is received, making it easier to visualize the structure of the body tissue and affected areas. Furthermore, in fluorescence observation, a drug (e.g., 5-ALA) that is excited by special light in the blue wavelength band and emits fluorescence in the red wavelength band may be used. The type of light irradiated by the light source device 5043 is set under the control of the CCU 5039. The CCU 5039 may have a mode in which normal light observation and special light observation are alternately performed by controlling the light source device 5043 and the endoscope 5001. In this case, it is preferable to superimpose information based on pixel signals obtained by special light observation on pixel signals obtained by normal light observation. The special light observation may be infrared light observation, which irradiates infrared light to view areas deeper than the surface of an organ, or multispectral observation using hyperspectral spectroscopy. Furthermore, photodynamic therapy may be combined.

[0212] [Recording Device] The recording device 5053 is a device, such as a recorder, that records pixel signals (e.g., images) acquired from the CCU 5039. The recording device 5053 records images acquired from the CCU 5039 on a HDD, SSD, or optical disk. The recording device 5053 may be connected to a network within the hospital so as to be accessible from devices outside the operating room. The recording device 5053 may also have an image down-conversion or up-conversion function.

[0213] [Display Device] The display device 5041 is a device capable of displaying an image, such as a display monitor. The display device 5041 displays an image based on pixel signals acquired from the CCU 5039. The display device 5041 may also function as an input device that enables gaze recognition, voice recognition, and instruction input using gestures by including a camera and a microphone.

[0214] [Output Device] The output device 5055 is a device, such as a printer, that outputs information acquired from the CCU 5039. The output device 5055 prints, for example, a print image based on pixel signals acquired from the CCU 5039 onto paper.

[0215] [Support Device] The support device 5027 is an articulated arm including a base 5029 having an arm control device 5045, an arm 5031 extending from the base 5029, and a holder 5032 attached to the tip of the arm 5031. The arm control device 5045 is configured with a processor such as a CPU and controls the drive of the arm 5031 by operating according to a predetermined program. The support device 5027 controls the position and posture of the endoscope 5001 held by the holder 5032, for example, by controlling parameters such as the length of each link 5035 constituting the arm 5031 and the rotation angle and torque of each joint 5033 using the arm control device 5045. This allows the endoscope 5001 to be changed to a desired position or posture, allowing the scope 5003 to be inserted into the patient 5071 and the observation area within the body to be changed. The support device 5027 functions as an endoscope support arm that supports the endoscope 5001 during surgery. This allows the support device 5027 to take the place of an assistant scopist who holds the endoscope 5001. The support device 5027 may also be a device that supports a microscope device 5301 (described later) and may also be called a medical support arm. The support device 5027 may be controlled autonomously by the arm control device 5045, or may be controlled by the arm control device 5045 based on user input. For example, the control method may be a master-slave method in which the support device 5027, which serves as a slave device (replica device) serving as a patient cart, is controlled based on the movement of a master device (primary device) that serves as an operator console near the user. The support device 5027 may also be remotely controlled from outside the operating room.

[0216] The above describes an example of an endoscope system 5000 to which the technology according to the present disclosure can be applied. For example, the technology according to the present disclosure may be applied to a microscope system.

[0217] 41 is a diagram showing an example of the schematic configuration of a microsurgical system to which the technology according to the present disclosure can be applied. In the following description, components similar to those in the endoscope system 5000 are designated by the same reference numerals, and redundant description thereof will be omitted.

[0218] 41 shows a schematic diagram of an operator 5067 performing surgery on a patient 5071 on a patient bed 5069 using a microsurgical system 5300. For simplicity, the illustration of the cart 5037 of the microsurgical system 5300 is omitted, and the illustration of the microscope device 5301 that replaces the endoscope 5001 is simplified. However, the microscope device 5301 in this description may refer to the microscope unit 5303 provided at the tip of the link 5035, or may refer to the entire configuration including the microscope unit 5303 and the support device 5027.

[0219] As shown in Figure 41, during surgery, a microsurgical system 5300 is used to display an enlarged image of the surgical site captured by a microscope device 5301 on a display device 5041 installed in an operating room. The display device 5041 is installed in a position facing the surgeon 5067, who performs various procedures on the surgical site, such as resecting the affected area, while observing the state of the surgical site using the image displayed on the display device 5041. Microsurgical systems are used, for example, in ophthalmic surgery and brain surgery.

[0220] The above describes examples of an endoscopic system 5000 and a microsurgery system 5300 to which the technology of the present disclosure can be applied. Note that the systems to which the technology of the present disclosure can be applied are not limited to these examples. For example, the support device 5027 may support another observation device or another surgical tool at its tip instead of the endoscope 5001 or the microscope unit 5303. Examples of such other observation devices include forceps, a surgeon, an insufflation tube for insufflation, or an energy treatment tool for incising tissue or sealing blood vessels by cauterization. Supporting these observation devices and surgical tools with a support device allows them to be more stably fixed in position than when medical staff support them manually, and also reduces the burden on medical staff. The technology of the present disclosure may be applied to support devices that support components other than the microscope unit.

[0221] Of the configurations described above, the technology according to the present disclosure can be suitably applied to the camera 5005. In particular, the imaging optical system according to the present disclosure can be suitably applied to at least some of the optical systems of the camera 5005: the focusing optical system 50051, the zoom optical system 50052, and the focus optical system 50053.

[0222] 6. Other Embodiments The technology according to the present disclosure is not limited to the above-described embodiment and examples, and various modifications are possible.

[0223] For example, the shapes and numerical values ​​of each part shown in the above embodiment and example are merely examples of specific embodiments for implementing this technology, and the technical scope of this technology should not be interpreted in a limited manner based on these.

[0224] Furthermore, for example, the lens system may be configured to include a number of lenses different from those shown in the above embodiment and example. Furthermore, the lens system may be configured to include a lens that has substantially no refractive power. Here, the lens that has substantially no refractive power is a lens that has no refractive power that would, in principle, affect the optical performance achieved by the lens system, such as a flat lens.

[0225] For example, the present technology can be configured as follows. According to the present technology configured as follows, the configuration of each lens group is optimized so that various aberrations are corrected, and it is possible to achieve a compact imaging optical system that suppresses fluctuations in the angle of view that accompany focusing. This makes it possible to provide an imaging optical system that corrects various aberrations, is compact, and suppresses fluctuations in the angle of view that accompany focusing, and an imaging device that includes such an imaging optical system.

[0226] [1] An imaging optical system comprising, in order from the object side to the image plane side, a first lens group, a second lens group having positive refractive power, and a third lens group having negative refractive power, wherein the second lens group moves in the optical axis direction during focusing, and the following conditional expression (1) is satisfied with respect to a focal length of the second lens group and a focal length of the third lens group, and the second lens group has a positive lens that satisfies the following conditional expressions (2) and (3). -0.80<f2 / f3<-0.25 ... (1) θgF+0.00325*νd>0.6825 ... (2) νd<25.0 ... (3) where, f2: focal length of the second lens group f3: focal length of the third lens group θgF: partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group νd: Abbe number based on the d-line of the positive lens in the second lens group. [2] The imaging optical system according to [1] above, further satisfying the following conditional expression: 0.9<|f1 / f|<5.0 ... (4) where, f1: focal length of the first lens group f: focal length of the entire system when focused at infinity. [3] The imaging optical system according to [1] above, further satisfying the following conditional expression: 0.9<|f1 / f|<5.0 ... (4) where, f1: focal length of the first lens group f: focal length of the entire system when focused at infinity. 1.0<f2 / f<3.0 ... (5) where, f2: focal length of the second lens group, f: focal length of the entire system when focused at infinity. [4] The imaging optical system according to any one of [1] to [3] above, further satisfying the following conditional expression: -7.0<f3 / f<-2.0 ... (6) where, f3: focal length of the third lens group, f: focal length of the entire system when focused at infinity. [5] The imaging optical system according to any one of [1] to [4] above, further satisfying the following conditional expression: 0.5<BF / f<1.2 ... (7) where, BF: distance on the optical axis from the lens surface closest to the image plane to the image plane, f: focal length of the entire system when focused at infinity. [6] The imaging optical system according to any one of [1] to [5] above, wherein the first lens group has an aperture stop that is fixed with respect to the image plane during focusing. [7] The imaging optical system according to any one of [1] to [6] above, wherein the second lens group has an aspherical lens closest to the image plane.[8] The imaging optical system according to any one of [1] to [7] above, wherein the first lens group has a negative lens closest to the object. [9] The imaging optical system according to any one of [1] to [8] above, wherein the first lens group has a plurality of lenses, and the second lens from the object side among the plurality of lenses has negative refractive power.

[10] The imaging optical system according to any one of [1] to [9] above, wherein the first lens group has an aspherical lens closest to the image plane.

[11] The imaging optical system according to any one of [1] to

[10] above, wherein the second lens group has a cemented lens.

[12] An imaging device including an imaging optical system and an imaging element that outputs an imaging signal corresponding to an optical image formed by the imaging optical system, wherein the imaging optical system consists of, in order from the object side to the image plane side, a first lens group, a second lens group having positive refractive power, and a third lens group having negative refractive power, wherein the second lens group moves in the optical axis direction during focusing, and the focal lengths of the second lens group and the third lens group satisfy the following conditional expression (1), and the second lens group has a positive lens that satisfies the following conditional expressions (2) and (3). -0.80<f2 / f3<-0.25 ... (1) θgF+0.00325*νd>0.6825 ... (2) νd<25.0 ... (3) where, f2: focal length of the second lens group f3: focal length of the third lens group θgF: partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group νd: Abbe number based on the d-line of the positive lens in the second lens group

[13] The imaging optical system according to any one of [1] to

[11] above, further comprising a lens having substantially no refractive power.

[14] The imaging device according to

[12] above, wherein the imaging optical system further comprises a lens having substantially no refractive power.

[0227] This application claims priority based on Japanese Patent Application No. 2024-092456, filed on June 6, 2024, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0228] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. An imaging optical system comprising, in order from the object side to the image plane side, a first lens group, a second lens group having positive refractive power, and a third lens group having negative refractive power, wherein the second lens group moves in the optical axis direction during focusing, and the focal lengths of the second lens group and the third lens group satisfy the following conditional expression (1), and the second lens group has a positive lens that satisfies the following conditional expressions (2) and (3). -0.80<f2 / f3<-0.25 ... (1) θgF+0.00325*νd>0.6825 ... (2) νd<25.0 ... (3) where, f2: focal length of the second lens group, f3: focal length of the third lens group, θgF: partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group, and νd: Abbe number of the positive lens in the second lens group based on the d-line.

2. The imaging optical system according to claim 1, further satisfying the following condition: 0.9<|f1 / f|<5.0 (4) where, f1: focal length of the first lens group, and f: focal length of the entire system when focused at infinity.

3. The imaging optical system according to claim 1, further satisfying the following condition: 1.0<f2 / f<3.0 (5) where f2 is the focal length of the second lens group, and f is the focal length of the entire system when focused at infinity.

4. The imaging optical system according to claim 1, further satisfying the following condition: -7.0<f3 / f<-2.0 (6) where f3 is the focal length of the third lens group, and f is the focal length of the entire system when focused at infinity.

5. The imaging optical system according to claim 1 further satisfies the following condition: 0.5<BF / f<1.2 (7) where BF is the distance on the optical axis from the lens surface closest to the image plane to the image plane, and f is the focal length of the entire system when focused at infinity.

6. The imaging optical system according to claim 1, wherein the first lens group has an aperture stop that is fixed with respect to the image plane during focusing.

7. The imaging optical system according to claim 1, wherein the second lens group has an aspherical lens closest to the image plane.

8. The imaging optical system according to claim 1, wherein the first lens group has a negative lens closest to the object side.

9. The imaging optical system according to claim 1, wherein the first lens group has a plurality of lenses, and the second lens from the object side among the plurality of lenses has negative refractive power.

10. The imaging optical system according to claim 1, wherein the first lens group has an aspherical lens closest to the image plane.

11. The imaging optical system according to claim 1, wherein the second lens group has a cemented lens.

12. An imaging device comprising an imaging optical system and an imaging element that outputs an imaging signal corresponding to an optical image formed by said imaging optical system, said imaging optical system consisting of, in order from the object side to the image plane side, a first lens group, a second lens group having positive refractive power, and a third lens group having negative refractive power, said second lens group moving in the optical axis direction during focusing, said second lens group and said third lens group satisfying the following conditional expression (1) with respect to the focal length of said second lens group and the focal length of said third lens group, and said second lens group having a positive lens that satisfies the following conditional expressions (2) and (3). -0.80<f2 / f3<-0.25 ... (1) θgF+0.00325*νd>0.6825 ... (2) νd<25.0 ... (3) where, f2: focal length of the second lens group, f3: focal length of the third lens group, θgF: partial dispersion ratio between the g-line and the F-line of the positive lens in the second lens group, and νd: Abbe number of the positive lens in the second lens group based on the d-line.

Images