Optical system and imaging apparatus

Abstract

To provide an optical system which is compact and has high optical performance.SOLUTION: The optical system 100 includes, in order from the object side to the image side, a first transmissive-reflective surface HM1, a quarter-wave plate QWP, and a second transmissive-reflective surface HM2. The optical system is a primary imaging system. Light from the object side is transmitted through the first transmitting / reflecting surface and the 1 / 4-wavelength plate in order, reflected to the object side by the second transmitting / reflecting surface, transmitted through the 1 / 4-wavelength plate, reflected to the image side by the first transmitting / reflecting surface, transmitted through the 1 / 4-wavelength plate and the second transmitting / reflecting surface in order, and directed to the image side. A length zm1 on the optical axis from the first transmitting / reflecting surface to the image plane and a focal distance f of the optical system satisfy a predetermined conditional equation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an optical system. [Background technology]

[0002] In recent years, there has been a demand for optical systems that are compact yet have good optical performance in imaging devices such as smartphones and mirrorless cameras. Examples of optical systems that have a short overall optical length while maintaining good optical performance include the periscope optical system disclosed in Patent Document 1 and the catadioptric optical system disclosed in Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 156933 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-015712 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it is difficult to reduce the size of the periscope optical system disclosed in Patent Document 1 in a direction perpendicular to the optical axis. Also, in the catadioptric optical system disclosed in Patent Document 2, it is difficult to make the light receiving element larger relative to the transmission hole in the primary mirror, making it difficult to obtain high optical performance relative to the size of the optical system.

[0005] The present invention provides an optical system that is compact and has high optical performance. [Means for solving the problem]

[0006] An optical system according to one aspect of the present invention has a first transmissive-reflective surface, a quarter-wave plate, and a second transmissive-reflective surface arranged in this order from the object side to the image side, wherein the optical system is a primary imaging system, in which light from the object side passes through the first transmissive-reflective surface and the quarter-wave plate in this order, is reflected by the second transmissive-reflective surface towards the object side, passes through the quarter-wave plate, is reflected by the first transmissive-reflective surface towards the image side, passes through the quarter-wave plate and the second transmissive-reflective surface in this order towards the image side, and when the distance on the optical axis from the first transmissive-reflective surface to the image plane is zm1 and the focal length of the optical system is f, then: 0.10≦zm1 / f≦0.68 The present invention is characterized in that the following conditional expression is satisfied:

[0007] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an optical system that is small in size and has high optical performance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic diagram illustrating an optical path of an optical system. [Figure 2] FIG. 2 is a schematic diagram illustrating an optical path of an optical system. [Figure 3] FIG. 2 is a cross-sectional view of an optical system according to the first embodiment. [Figure 4] 3A to 3C are aberration diagrams of the optical system in Example 1. [Figure 5] FIG. 10 is a cross-sectional view of an optical system according to a second embodiment. [Figure 6] 10A to 10C are aberration diagrams of the optical system in Example 2. [Figure 7] FIG. 10 is a cross-sectional view of an optical system according to a third embodiment. [Figure 8] 10A to 10C are aberration diagrams of the optical system in Example 3. [Figure 9] FIG. 10 is a cross-sectional view of an optical system according to a fourth embodiment. [Figure 10] 10A to 10C are aberration diagrams of the optical system in Example 4. [Figure 11]FIG. 10 is a cross-sectional view of an optical system according to a fifth embodiment. [Figure 12] 10A to 10C are aberration diagrams of the optical system in Example 5. [Figure 13] FIG. 10 is a cross-sectional view of an optical system according to a sixth embodiment. [Figure 14] 10A to 10C are aberration diagrams of the optical system in Example 6. [Figure 15] FIG. 10 is a cross-sectional view of an optical system according to a seventh embodiment. [Figure 16] 10A to 10C are aberration diagrams of the optical system in Example 7. [Figure 17] FIG. 13 is a cross-sectional view of an optical system according to an eighth embodiment. [Figure 18] 13A to 13C are aberration diagrams of the optical system in Example 8. [Figure 19] FIG. 13 is a cross-sectional view of an optical system according to a ninth embodiment. [Figure 20] 13A to 13C are aberration diagrams of the optical system in Example 9. [Figure 21] FIG. 20 is a cross-sectional view of an optical system according to a tenth embodiment. [Figure 22] 13A to 13C are aberration diagrams of the optical system in Example 10. [Figure 23] FIG. 20 is a cross-sectional view of an optical system according to an eleventh embodiment. [Figure 24] 13A to 13C are aberration diagrams of the optical system in Example 11. [Figure 25] FIG. 20 is a cross-sectional view of an optical system according to a twelfth embodiment. [Figure 26] 13A to 13C are aberration diagrams of the optical system in Example 12. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] The imaging optical system in each embodiment is an optical system that forms an image of an object on an image plane, and is an optical system for acquiring an image using a solid-state image sensor or photosensitive film arranged on the image plane.

[0012] The imaging optical system of each embodiment has, arranged in order from the object side to the image side, a first transmissive-reflective surface, a quarter-wave plate (QWP), and a second transmissive-reflective surface. Light from the object side passes through the first transmissive-reflective surface and the QWP in that order, and is reflected by the second transmissive-reflective surface. The light then passes through the QWP, is reflected by the first transmissive-reflective surface, passes through the QWP, and the second transmissive-reflective surface, and heads toward an imaging unit such as a solid-state image sensor or photosensitive film.

[0013] Here, the first and second transmissive-reflective surfaces do not necessarily have to have a transmittance of 50% and a reflectance of 50%. The ratio of transmittance to reflectance for randomly polarized light is preferably in the range of 1:3 to 3:1. Randomly polarized light is light with Stokes parameters S0 = 1, S1 = S2 = S3 = 0. Furthermore, the first and second transmissive-reflective surfaces may absorb light.

[0014] Furthermore, a lens may be formed or cemented to one or both sides of each of the transmission / reflection surfaces.

[0015] For example, a birefringent polymer film or a liquid crystal alignment layer can be used as a QWP. A stack of such polymer films or liquid crystal alignment layers can also be used as a QWP. By appropriately stacking these, a phase difference close to one-quarter of the wavelength can be obtained over a wide wavelength range. In addition to the above, inorganic wave plates from Dexerials Corporation can also be used as QWPs.

[0016] The QWP can be arranged by bonding it to, for example, a first transflective surface or a second transflective surface. Alternatively, the QWP can be arranged separately from these transflective surfaces. For example, a film can be inserted directly into the optical path, or a film bonded to a glass plate can be inserted into the optical path. Alternatively, lenses can be formed or bonded to one or both sides of the QWP. For example, lenses can be molded on one or both sides of an inorganic waveplate using wafer-level optics technology as a substrate.

[0017] The imaging optical system of each embodiment satisfies the following conditional expression (1): Here, the distance on the optical axis from the first transmissive-reflective surface to the image plane is zm1, and the focal length of the imaging optical system is f.

[0018] 0.10≦zm1 / f≦0.68 (1) If the lower limit of conditional expression (1) is exceeded, the optical path length of the portion where the light rays are folded back is not sufficiently ensured, resulting in a long overall length of the imaging optical system. If the upper limit of conditional expression (1) is exceeded, the power (refractive power) of the first transmissive-reflective surface and the second transmissive-reflective surface cannot be increased. If the power of these transmissive-reflective surfaces is small, the proportion of power due to refraction increases. This increases chromatic aberration and reduces image quality. Furthermore, if the power of these transmissive-reflective surfaces is small, it becomes difficult to significantly bend light incident off-axis. This results in a small image circle, making it difficult to achieve a wide angle and high image quality as an imaging system.

[0019] Incidentally, focal length is defined as the ratio of the height of a ray of light incident on a paraxial region that is parallel to the optical axis from infinity to the angle of emergence of that ray when it leaves the optical system, as described in "Introduction to Imaging Optics: Fundamentals of Handling Optical Systems" by Yoshiya Matsui, Japan Optomechatronics Association, 1988, pp. 45-48. As defined in the above document, the sign of the focal length of an optical system that forms an intermediate image (forms an intermediate image), i.e., a secondary imaging system, is negative.

[0020] To achieve both high performance and compactness in the imaging optical system alone, it is sufficient to make the entire imaging optical system as small as possible. Aberrations other than distortion also decrease in proportion to the size reduction, making it possible to realize an imaging optical system that is compact and has high optical performance. However, such an imaging optical system also requires a small imaging surface, which prevents the imaging system from achieving high optical performance as a whole. This is because the imaging surface is occupied by a solid-state imaging device or photosensitive film, and there are technical limitations to the pixel density of the solid-state imaging device and the resolution per unit area of ​​the photosensitive film. Furthermore, the diffraction limit dictates the minimum meaningful pixel size. Therefore, to achieve high image quality in an imaging system, it is preferable for the imaging optical system to have low aberrations while supporting a large image circle.

[0021] It is also preferable that the imaging optical system of each embodiment satisfy the following conditional expression (2): Here, the total length of the imaging optical system excluding the diaphragm is La, the image circle radius is h, and the F-number of the imaging optical system is Fno.

[0022] 0.0≦La×h×Fno / f2≦2.6 (2) The total length of an imaging optical system excluding the diaphragm refers to the total length of the imaging optical system excluding the diaphragm in an imaging optical system in which an aperture diaphragm or a diaphragm with a fixed diameter that acts as a light-blocking mask is located closest to the object. In other imaging optical systems, it refers to the total length of the imaging optical system. The total length of an imaging optical system is the distance on the optical axis from the optical surface closest to the object to the image plane. In other words, the total length of an imaging optical system excluding the diaphragm can also be said to be the distance on the optical axis from the lens surface closest to the object to the image plane.

[0023] By definition, the lower limit of conditional expression (2) cannot be exceeded. Exceeding the upper limit of conditional expression (2) increases the angle of incidence of off-axial light onto the image plane. This reduces the exit pupil for the off-axial region, resulting in reduced resolution due to diffraction or an increase in the overall length, which is undesirable. Furthermore, a larger angle of incidence onto the image plane is undesirable because it increases the likelihood of optical crosstalk occurring in peripheral pixels when a solid-state image sensor is used as the image sensor.

[0024] It is preferable that the imaging optical system of each embodiment satisfies the following conditional expression (3): where zp is the distance on the optical axis from the aperture stop to the image plane.

[0025] 0.1≦zp / f≦1.2 (3) If the imaging optical system does not have an aperture stop, the surface that restricts the diameter of the light beam is defined as the surface closest to the object, and the distance on the optical axis from this surface closest to the object to the image plane is defined as zp. The aperture stop is a stop that can change the area through which light passes, such as an iris stop or a Waterhouse stop. The aperture stop does not necessarily require physical blocking, and may instead be one that controls the color density distribution by applying a voltage using, for example, an electrochromic element.

[0026] If the lower limit of conditional expression (3) is not met, and if the imaging optical system has an aperture stop, vignetting of the upper line is likely to occur due to the aperture stop, which is not preferable. If the imaging optical system does not have an aperture stop, vignetting of the upper line is likely to occur due to the outer diameter of the lens, which is not preferable. If the upper limit of conditional expression (3) is met, and if the imaging optical system has an aperture stop, This is undesirable because the aperture stop tends to cause vignetting of the underline. If the imaging optical system does not have an aperture stop, the outer diameter of the lens tends to cause vignetting of the underline, which is also undesirable. While it is possible to reduce vignetting by increasing the diameter of the imaging optical system, this approach results in an increase in the overall size of the imaging optical system. This type of vignetting of light rays has the disadvantages of reducing peripheral illumination and shrinking the image circle. Furthermore, because the area of ​​the exit pupil is reduced, diffraction causes a deterioration in the frequency characteristics in the meridional direction, resulting in a decrease in image quality.

[0027] The imaging optical system of each embodiment preferably satisfies the following conditional expression (4): Here, the diameter of the first transmitting-reflecting surface is Φm1, and the diameter of the second transmitting-reflecting surface is Φm2. Here, the "diameter" refers to the diameter of the effective area of ​​the transmitting-reflecting surface (the area through which effective light rays that contribute to imaging pass).

[0028] 0.50≦Φm1 / Φm2≦1.25 (4) If the lower limit of conditional expression (4) is exceeded, the angle of incidence of off-axial light onto the image plane becomes large, the exit pupil for the off-axial region becomes small, and resolution decreases due to diffraction, which is undesirable. Furthermore, if the angle of incidence onto the image plane becomes large, optical crosstalk tends to occur in peripheral pixels when a solid-state image sensor is used as the image sensor, which is undesirable. If the upper limit of conditional expression (4) is exceeded, off-axial light rays are vignetted by the second transflective surface, the exit pupil for the off-axial region becomes small, and resolution decreases due to diffraction, which is undesirable. Moreover, if the upper limit of conditional expression (4) is exceeded, the image circle becomes small, which is undesirable as it reduces the image quality of the imaging system.

[0029] It is preferable that the imaging optical system of each embodiment satisfies the following conditional expression (5).

[0030] 0.1≦h / (Φm2 / 2) / Fno≦1.2 ···(5) If the lower limit of conditional expression (5) is exceeded, the lens diameter becomes too small relative to the size of the imaging surface. This is undesirable because it becomes difficult to improve the optical performance of the imaging system while increasing the size of the imaging optical system. Furthermore, if an attempt is made to achieve the highest possible image quality with a small imaging unit, the sensitivity of each surface increases, which is undesirable because it reduces manufacturing yield. If the upper limit of conditional expression (5) is exceeded, the angle of incidence of off-axial light on the image plane increases, the exit pupil for the off-axial region becomes smaller, and diffraction reduces resolution or increases the overall length, which is undesirable. Furthermore, if the angle of incidence on the image plane becomes large, optical crosstalk is more likely to occur in peripheral pixels when a solid-state imaging device is used as the imaging device, which is undesirable.

[0031] It is preferable that the imaging optical system of each embodiment satisfies the following conditional expression (6): Here, the distance on the optical axis from the second transmissive-reflective surface to the image plane is denoted by zm2.

[0032] 0.0≦zm2 / La≦0.5 (6) By definition, the lower limit of conditional expression (6) cannot be exceeded. Exceeding the upper limit of conditional expression (6) is undesirable because it shortens the optical path length along which the light beam returns, thereby lengthening the overall length.

[0033] It is preferable that the imaging optical system of each embodiment satisfies the following conditional expression (7): Here, the absolute value of the refractive power of the lens including the second transmissive-reflective surface is denoted by Φm1L.

[0034] 0.0≦Φm1L×f≦1.0 (7) By definition, the lower limit of conditional expression (7) cannot be exceeded. If the upper limit of conditional expression (7) is exceeded, the refractive power at high light ray heights becomes too strong, resulting in significant axial chromatic aberration. This is not desirable because it results in poor image quality.

[0035] The imaging optical system of each embodiment preferably satisfies the following conditional expression (8): Here, the average value of the absolute values ​​of the refractive powers of the multiple lenses included in the imaging optical system is AΦr, and the average value of the absolute values ​​of the powers (refractive powers) of the first transmissive-reflective surface and the second transmissive-reflective surface is AΦm. The power (reflective power) of a reflecting surface corresponds to the reciprocal of the paraxial focal length of the reflecting surface; for example, in the case of a spherical surface, this is the reciprocal of the paraxial radius of curvature multiplied by -2. Even when a reflecting surface is used as a back-coated mirror, the reflective component of its power is the reciprocal of the paraxial radius of curvature multiplied by -2 (for example, if the shape is spherical), and this value is used when calculating AΦr.

[0036] 0.0≦AΦr / AΦm≦0.5 (8) In addition, although a ray of light passes through the lens placed between the first and second transmissive-reflective surfaces three times, when calculating AΦr, it is assumed that the ray of light passes through the lens only once.

[0037] By definition, the lower limit of conditional expression (8) cannot be exceeded. If the upper limit of conditional expression (8) is exceeded, refractive power will dominate over reflective power in the entire imaging optical system. Reflecting surfaces, by their very nature, do not produce chromatic aberration during reflection. On the other hand, chromatic aberration occurs during lens refraction. Therefore, increasing the refractive power of the entire system is undesirable because it results in the appearance of axial chromatic aberration and lateral chromatic aberration, which impairs image quality. Furthermore, satisfying conditional expression (8) reduces the occurrence of chromatic aberration for the reasons described above. This allows the imaging optical system to be an optical system capable of imaging from the visible to infrared ranges, or an optical system capable of imaging over a wide infrared wavelength range. In this case, it is preferable to use quarter-wave plates and transmissive-reflective surfaces that can fully demonstrate their respective functions in the wavelength range to be used.

[0038] It is preferable that the imaging optical system of each embodiment satisfies the following conditional expression (9).

[0039] 0.0≦La×h / f2≦2.0 (9) By definition, the lower limit of conditional expression (9) cannot be exceeded. Exceeding the upper limit of conditional expression (9) undesirably increases the angle of incidence of off-axial light onto the image plane, reduces the exit pupil for the off-axial region, and reduces resolution due to diffraction or increases the overall length. Furthermore, if the angle of incidence on the image plane becomes large, optical crosstalk is likely to occur in the surrounding pixels when a solid-state image sensor is used as the image sensor, which is undesirable.

[0040] In the imaging optical system of each embodiment, a loss of light occurs due to the first and second transmissive-reflective surfaces. As a result, if the F-number is large, the amount of light reaching the image sensor becomes very small. For this reason, it is preferable that the imaging optical system of each embodiment satisfy the following conditional expression (10):

[0041] 0.5≦Fno≦8.0 (10) In the imaging optical system of each embodiment, it is preferable that either the first transmission-reflection surface or the second transmission-reflection surface, or both the first transmission-reflection surface and the second transmission-reflection surface, are flat, which is preferable because it makes it easier to manufacture the imaging optical system.

[0042] It is more preferable that the numerical ranges of the conditional expressions (1) to (10) be within the ranges of the following conditional expressions (1a) to (10a).

[0043] 0.10≦zm1 / f≦0.67 (1a) 0.0≦La×h×Fno / f2≦2.5 (2a) 0.1≦zp / f≦1.0 (3a) 0.60≦Φm1 / Φm2≦1.20 (4a) 0.1≦h / (Φm2 / 2) / Fno≦1.1 (5a) 0.00≦zm2 / La≦0.48 (6a) 0.0≦Φm1L×f≦0.7 (7a) 0.0≦AΦr / AΦm≦0.3 (8a) 0.0≦La×h / f2≦1.8 (9a) 0.8≦Fno≦6.0 (10a) It is more preferable that the numerical ranges of the conditional expressions (1) to (10) be within the ranges of the following conditional expressions (1b) to (10b).

[0044] 0.10≦zm1 / f≦0.65 (1b) 0.0≦La×h×Fno / f2≦2.4 (2b) 0.1≦zp / f≦0.95 (3b) 0.60≦Φm1 / Φm2≦1.10 (4b) 0.1≦h / (Φm2 / 2) / Fno≦1.0 (5b) 0.00≦zm2 / La≦0.46 (6b) 0.0≦Φm1L×f≦0.5 (7b) 0.00≦AΦr / AΦm≦0.25 (8b) 0.0≦La×h / f2≦1.7 (9b) 1.0≦Fno≦4.0 (10b) It is more preferable that the numerical ranges of the conditional expressions (1) to (10) be within the ranges of the following conditional expressions (1c) to (10c).

[0045] 0.10≦zm1 / f≦0.55 (1c) 0.0≦La×h×Fno / f2≦2.0 (2c) 0.1≦zp / f≦0.65 (3c) 0.60≦Φm1 / Φm2≦1.05 (4c) 0.1≦h / (Φm2 / 2) / Fno≦0.8 (5c) 0.00≦zm2 / La≦0.15 (6c) 0.0≦Φm1L×f≦0.35 (7c) 0.00≦AΦr / AΦm≦0.15 (8c) 0.0≦La×h / f2≦1.0 (9c) 1.0≦Fno≦2.5 (10c) It is preferable that either the first transflective surface or the second transflective surface is a surface that separates incident light into reflected light and transmitted light according to the polarization state. Specifically, as described below, it is preferable to use a polarization-selective transflective element as either the first transflective surface or the second transflective surface. Examples of polarization-selective transflective elements include those manufactured by Asahi Kasei Corporation under the trade name "WGF," those manufactured by 3M Company under the trade name "IQPE," and those manufactured by MOXTEK under the trade name "ProFlux." The other transflective surface can be, for example, a half mirror. When a half mirror is used, the amount of randomly polarized light incident from the object side is reduced to 12.5% ​​or less by the time it reaches the image plane.

[0046] Furthermore, a cholesteric liquid crystal or a holographic optical element may be used as the transmissive / reflective surface.

[0047] In the imaging optical system of each embodiment, an optical element may be used as the polarization-selective transmission / reflection element by forming a grid on the lens reflecting surface during lens molding and then depositing, printing, or lithographically depositing a metal or dielectric material thereon.

[0048] Furthermore, it is preferable that the shape of the effective area of ​​each of the plurality of lens surfaces included in the imaging optical system of each embodiment is rotationally symmetric with respect to the optical axis. When the imaging optical system is rotationally symmetric in the effective area of ​​each optical surface, the method of positioning each optical element can be simplified. Furthermore, when the imaging optical system is rotationally symmetric, including the outer shape of each optical element, the ease of manufacture can be further improved.

[0049] Furthermore, in the imaging optical system of each embodiment, for example, by adopting the following configuration, it is possible to suppress a decrease in the amount of light in the normal imaging optical path while reducing ghost light (unwanted light leakage) from the optical path that passes through the transmissive-reflective surface without ever reflecting. [Configuration 1 Using Polarized Light] A configuration using polarized light will be described with reference to Figure 1. The imaging optical system of this configuration has two transmissive / reflective surfaces. Here, the transmissive / reflective surface located on the object side of the imaging optical system of this configuration is configured by placing a polarization-selective transmissive / reflective element (PBS):A. The transmissive / reflective surface located on the image plane side of the imaging optical system of this configuration is configured by placing a half mirror (HM):C. In addition, a first quarter-wave plate (QWP1):B is placed between the polarization-selective transmissive / reflective element PBS and the half mirror HM. A second quarter-wave plate (QWP2):D and a linear polarizer (POL):E are placed between the half mirror HM and the imaging plane IM, in that order from the object side to the image side.

[0050] Here, the polarization-selective transmission / reflection element A is an element configured to reflect linearly polarized light polarized in the same direction as when it passed through the linear polarizer E, and to transmit linearly polarized light perpendicular to this. The polarization-selective transmission / reflection element A is, for example, a wire grid polarizer or a reflective polarizer having a laminated retardation film structure. In this case, the wire grid-formed surface or retardation film surface of the polarization-selective transmission / reflection element A functions as the transmission / reflection surface. Note that the wire grid polarizer does not necessarily have to be one in which metal wires are aligned, as long as it has thin metal or dielectric layers at predetermined intervals and functions as a polarization-selective transmission / reflection element. For example, an element in which metal or dielectric layers are aligned by vapor deposition can be used.

[0051] The first quarter-wave plate B and the second quarter-wave plate D are arranged with their slow axes tilted at 45° with respect to the polarization transmission axis of the linear polarizer E. Preferably, the first quarter-wave plate B and the second quarter-wave plate D are arranged with their slow axes tilted at 90°. With this arrangement, when light passes through the first quarter-wave plate B and the second quarter-wave plate D, the wavelength dispersion characteristics of the wave plates cancel each other out.

[0052] The half mirror C is formed of, for example, a dielectric multilayer film or metal vapor deposition, and the mirror surface of the half mirror C functions as a transmission / reflection surface. The linear polarizer E is, for example, an absorptive linear polarizer.

[0053] Next, the optical path selection and operation in the polarization utilization configuration will be described.

[0054] Light incident on the imaging optical system from the object side becomes linearly polarized light by the polarization-selective transmission / reflection element A, The light is converted into circularly polarized light by the first quarter-wave plate B and enters the half mirror C. A portion of the light that reaches the half mirror C is reflected and converted into reverse circularly polarized light, returning to the first quarter-wave plate B.

[0055] The counter-circularly polarized light that returned to the first quarter-wave plate B is returned to the polarization-selective transmission-reflection element A by the first quarter-wave plate B as linearly polarized light polarized in a direction perpendicular to the direction when the light first passed through the polarization-selective transmission-reflection element A. The light that returned to the polarization-selective transmission-reflection element A is reflected by the polarization-selective transmission-reflection element A. Here, due to the polarization selectivity of the polarization-selective transmission-reflection element A, linearly polarized light polarized in a direction perpendicular to the direction when the light first passed through the polarization-selective transmission-reflection element A is reflected.

[0056] On the other hand, part of the light that reaches the half mirror C is transmitted and becomes linearly polarized light polarized in the same direction as when it passed through the polarization-selective transmission-reflection element A by the second quarter-wave plate D, and is incident on the linear polarizer E and absorbed by the linear polarizer E.

[0057] The light reflected by the polarization-selective transmission / reflection element A is converted into circularly polarized light by the first quarter-wave plate B and enters the half mirror C. A portion of the light that reaches the half mirror C is transmitted and enters the second quarter-wave plate D. The second quarter-wave plate D converts the incident light into linearly polarized light that is oriented parallel to the linearly polarized light reflected by the polarization-selective transmission / reflection element A. The light that passes through the second quarter-wave plate D enters the linear polarizer E. Here, the polarization of the light and the transmission axis of the linear polarizer E are aligned, so most of the light is transmitted and directed to the imaging plane IM.

[0058] Due to the above-mentioned action, only the light that has been transmitted through the polarization-selective transmission / reflection element PBS, reflected by the half mirror C, reflected by the polarization-selective transmission / reflection element PBS, and transmitted through the half mirror C is guided to the imaging plane IM.

[0059] Furthermore, solid-state imaging devices and CCDs (Charge Coupled Devices) that can be used as the imaging surface IM generally have high surface reflectance. The light reflected by the imaging plane IM passes through the linear polarizer E again and is converted into circularly polarized light by the second quarter-wave plate D. After that, the light that leaves the second quarter-wave plate D is reflected by the half mirror C and becomes circularly polarized light in the opposite direction, and passes through the second quarter-wave plate D again. At this time, the circularly polarized light is converted by the second quarter-wave plate D into linearly polarized light in a direction perpendicular to that immediately after it passed through the linear polarizer E. Because the direction of this linearly polarized light is perpendicular to the transmission axis of the linear polarizer E, Most of the light is absorbed by the linear polarizer E. In this way, with this configuration, most of the light that reflects off the imaging plane IM and then the half mirror C is blocked, making ghosts and flare caused by the imaging plane IM less noticeable. In order to achieve this reflection reduction effect, it is preferable that no optical low pass filter that utilizes birefringence be located between the imaging plane IM and the linear polarizer E. This is because an optical low pass filter would cause the polarization state to deviate from the desired polarization state.

[0060] In this configuration, a quarter-wave plate may be placed between the polarization-selective transmission / reflection element A and the object. In this case, the quarter-wave plate is placed so that the fast axis or slow axis of the quarter-wave plate forms a 45° angle with the transmission axis of the polarization-selective transmission / reflection element A. By doing so, even if the light incident from the object side is linearly polarized, it is possible to capture an image regardless of its polarization direction. Furthermore, a depolarizing element may be placed instead of the quarter-wave plate. For example, Toyobo Co., Ltd.'s "Cosmoshine SRF" can be used as the depolarizing element.

[0061] [Polarized Configuration 2] A configuration using polarized light will be described with reference to FIG. The imaging optical system of this configuration has two transmissive-reflective surfaces. Here, the transmissive-reflective surface located on the object side of the imaging optical system of this configuration is configured by placing a half mirror (HM):C. In addition, the transmissive-reflective surface located on the imaging surface side of the imaging optical system of this configuration is configured by placing a polarization-selective transmissive-reflective element (PBS):A. In addition, a first quarter-wave plate (QWP1):B is placed between the polarization-selective transmissive-reflective element PBS and the half mirror HM. Between the half mirror HM and the object surface, a linear polarizer (POL):E and a second quarter-wave plate (QWP2):D are placed, in that order from the object side to the image side.

[0062] Here, the configuration of each polarizing element and the preferred arrangement of the optical axis orientation are the same as in the polarized light-utilizing configuration 1.

[0063] Next, the optical path selection and operation in the polarization utilization configuration will be described.

[0064] Light entering the imaging optical system from the object side becomes linearly polarized light by linear polarizer E, then becomes circularly polarized light by second quarter-wave plate D, and enters half mirror C. Part of the light that reaches half mirror C is reflected and becomes circularly polarized in the reverse direction, returning to the second quarter-wave plate D.

[0065] The light that reaches and is reflected by half mirror C is circularly polarized in the opposite direction to when it was incident. This light is then transformed by second quarter-wave plate D into linearly polarized light polarized in the direction perpendicular to when it passed through linear polarizer E, and is then incident on and absorbed by linear polarizer E.

[0066] Meanwhile, the light that passes through half mirror C is converted by first quarter-wave plate B into linearly polarized light polarized in the same direction as the light immediately after passing through linear polarizer E. This linearly polarized light is reflected by polarization-selective transmission / reflection element A and returns to first quarter-wave plate B. The light is then converted into circularly polarized light by first quarter-wave plate B, and a portion of this circularly polarized light is reflected by half mirror C. The light reflected by half mirror C enters first quarter-wave plate B again and is converted into linearly polarized light whose polarization direction is orthogonal to that when it was reflected by polarization-selective transmission / reflection element A. This linearly polarized light passes through polarization-selective transmission / reflection element A and is directed to the imaging plane IM.

[0067] Due to the above-mentioned action, only the light that passes through the half mirror C, is reflected by the polarization-selective transmission / reflection element PBS, is reflected by the half mirror C, and is transmitted through the polarization-selective transmission / reflection element PBS is guided to the imaging plane IM.

[0068] In this arrangement, a linear polarizer A' may be placed between the polarization-selective transmission / reflection element A and the imaging plane IM. In this case, the transmission axes of the linear polarizer A' and the polarization-selective transmission / reflection element A are aligned. In this way, it is possible to absorb light that is reflected by the imaging plane IM, further reflected by the polarization-selective transmission / reflection element A, and then re-enters the imaging plane IM, causing ghosts and flares.

[0069] In this configuration, a quarter-wave plate may be placed between the linear polarizer E and the object. In this case, the quarter-wave plate is positioned so that the fast axis or slow axis thereof forms a 45° angle with the transmission axis of the linear polarizer E. This makes it possible to capture an image regardless of the polarization direction of the linearly polarized light incident from the object side. Alternatively, a depolarizing element may be used instead of the quarter-wave plate. For example, Toyobo Co., Ltd.'s "Cosmoshine SRF" can be used as the depolarizing element.

[0070] In the above description of the configuration, terms such as orthogonal, parallel, and 45° are used, but these do not necessarily have to be strictly 90°, 0°, or 45°. However, these should be within ±5° of the desired angle, preferably within ±2°, and even more preferably within ±1°.

[0071] In the imaging optical system of each embodiment, the lenses may be made of either a polymer material or a glass material, but it is preferable that the lens disposed between the first and second transmissive-reflective surfaces has low birefringence.

[0072] Furthermore, in the above two configurations, the quarter-wave plate may be, for example, a polymer film such as "WA-140T" manufactured by Nippon Kayaku Co., Ltd., "CP3" manufactured by Colorlink Japan Co., Ltd., or "ZEONORFILM" manufactured by Zeon Corporation. Other examples that can be used include "APAW," "APSAW-5," and "APSAW-7" manufactured by Astropribor, and "Super Achromatic Wave Plate" (model numbers: SAQWP05M-700, SAQWP05M-1700, etc.) and "Achromatic Wave Plate" (model numbers: AQWP05M-600, AQWP05M-580, AQWP10M-580, etc.) manufactured by Thorlabs.

[0073] When a quarter-wave plate placed between two transflective surfaces has insufficient characteristics (i.e., it deviates from the ideal characteristic of providing only a quarter-wave phase delay, but provides a phase difference that is too large or too small, or it contains components that act as depolarizers or optical rotators), ghost and flare increase. Specifically, if the phase difference deviates from the quarter-wave, light reflected twice by each of the two transflective surfaces reaches the image plane as ghost and flare. For light incident on the optical axis, if the phase difference provided by the quarter-wave plate is δ (degrees), the intensity of the ghost light is expressed as {(1-cos(2δ))^2}×(1+cos(2δ))×a / 64 (where a is a constant that summarizes the absorption and reflection factors of each lens in the optical system). Note that the polarizer here is assumed to have ideal characteristics (i.e., it absorbs all light polarized along the absorption axis and transmits all light polarized along the transmission axis). This ghost light is tentatively referred to as a five-pass ghost.

[0074] Since the amount of light in the normal light path (preferably the light path that the light ray passes through) explained in the above configuration is {(1-cos(2δ))^2}×a / 16, the ratio of the amount of light in the normal light to the five-pass ghost light path is 4 / (1+cos(2δ)). Therefore, if the phase difference provided by the quarter-wave plate deviates from 90°, the amount of light in the five-pass ghost relative to the normal light increases rapidly, resulting in a strong ghost.

[0075] For this reason, in the wavelength band used (the wavelength band that is mainly used), if the element in the second row and second column of the Mueller matrix corresponding to the quarter-wave plate placed between the two transmissive-reflective surfaces is a22 and the element in the third row and second column is a32, it is desirable to satisfy the following conditional expressions (11a) and (12a).

[0076] -0.25≦a22≦0.25 (11a) -0.25≦a32≦0.25 (12a) This approach effectively suppresses five-pass ghosts. The above Mueller matrix represents the quarter-wave plate viewed from the incident side when linearly polarized light is perpendicularly incident on the plate. It represents the case where the angle between the axis corresponding to the fast axis (or slow axis) and the incident polarization is 45°. The wavelength range primarily used is the range in which the light-receiving element, such as an image sensor or photosensitive film, has sufficient sensitivity and where reflection and absorption in the optical system are sufficiently small. If the wavelength of the incident light is limited, the spectral spectrum of the incident light must also be taken into consideration. Specifically, the wavelength range used is the range in which the product of the sensitivity of the light-receiving element, the efficiency of the optical system, and the spectrum of the incident light is 10% or more or 20% or more of its peak.

[0077] Furthermore, it is more preferable that conditional expressions (11a) and (12a) be changed to conditional expressions (11b), (12b), (11c), (12c), (11d), and (12d), respectively.

[0078] -0.20≦a22≦0.20 (11b) -0.20≦a32≦0.20 (12b) -0.10≦a22≦0.10 (11c) -0.10≦a32≦0.10 (12c) -0.05≦a22≦0.05 (11d) -0.05≦a32≦0.05 (12d) Quarter-wave plate configurations that satisfy these conditions across the entire visible range (e.g., 420 nm to 680 nm) include, for example, an HQ-type quarter-wave plate, which is made by stacking a half-wave plate with its optical axis tilted by approximately 15° with respect to the incident polarization direction and a quarter-wave plate with its optical axis tilted by approximately 75°, and a Pancharatnam-type quarter-wave plate, which is made by combining two half-wave plates and one quarter-wave plate at a predetermined angle (for example, typically, the optical axes are at 6.5°, 34.57°, and 101.13° with respect to the incident polarization direction), and these are suitable for use as quarter-wave plates in the present invention.

[0079] The aforementioned "CP3," "APSAW-5," "APSAW-7," and "super achromatic waveplate" are Pancharatnam-type waveplates.

[0080] It is also preferable to use the other quarter-wave plate (i.e., D in Figures 1 and 2) with characteristics similar to those of the above-mentioned wave plate. For light that is not reflected even once by the two transmission-reflection surfaces, these two quarter-wave plates each act once to cancel out the other, preventing the light from reaching the image plane. For this reason, it is preferable for the characteristics of the two quarter-wave plates to be as similar as possible, as this will result in a state where the characteristics are canceled out completely.

[0081] Furthermore, it is desirable that the optical system of this embodiment be an optical system that does not form an intermediate image (does not form an intermediate image), i.e., a primary imaging system. In a primary imaging system, an image plane is formed at the position where incident light is first focused. This makes it possible to keep the overall length of the optical system short. Furthermore, with a primary imaging system, it is not necessary to strengthen the power of each lens compared to an optical system that forms an intermediate image (does form an intermediate image), i.e., a secondary imaging system, and therefore aberration correction is easier than with a secondary imaging system.

[0082] The configuration of the imaging optical system in each embodiment will be described below. [Example]

[0083] The imaging optical system 100 in Example 1 will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view of the imaging optical system 100. The imaging optical system 100 includes the following components arranged in order from the object side to the image side: The optical system is composed of a first lens 101 having a first transmission-reflection surface HM1, a second lens 102, a third lens 103 having a second transmission-reflection surface HM2, and a sensor protective glass GB. The first lens 101 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0084] FIG. 4 is a diagram showing aberrations of the imaging optical system 100 when focused at infinity, and shows the aberrations of the imaging optical system 100 at wavelengths of the d-line, F-line, C-line, and g-line.

[0085] In this imaging optical system 100, focusing is performed by moving the first lens 101, the second lens 102, and the third lens 103 together in the direction of the optical axis. [Example]

[0086] An imaging optical system 200 according to the second embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view of the imaging optical system 200. The imaging optical system 200 includes the following components arranged in order from the object side to the image side: The optical system is composed of a first lens 201 having a first transmission-reflection surface HM1, a second lens 202, a third lens 203 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The first lens 201 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0087] FIG. 6 is a diagram showing aberrations of the imaging optical system 200 when focused at infinity, and is a diagram showing aberrations of the imaging optical system 200 at wavelengths of the d-line, F-line, C-line, and g-line.

[0088] In this imaging optical system 200, focusing is performed by moving the first lens 201, the second lens 202, and the third lens 203 together in the direction of the optical axis. [Example]

[0089] An imaging optical system 300 according to a third embodiment will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view of the imaging optical system 300. The imaging optical system 300 includes the following components arranged in order from the object side to the image side: The optical system is composed of a first lens 301, an aperture stop SP, a second lens 302 having a first transmission-reflection surface HM1, a third lens 303, a fourth lens 304 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The second lens 302 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0090] FIG. 8 is a diagram showing aberrations when the imaging optical system 300 is focused at infinity, and is a diagram showing aberrations at wavelengths of the d-line, F-line, C-line, and g-line.

[0091] In this imaging optical system 300, focusing is performed by moving the first lens 301, second lens 302, third lens 303, and fourth lens 304 together in the direction of the optical axis. [Example]

[0092] An imaging optical system 400 according to the fourth embodiment will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view of the imaging optical system 400. The imaging optical system 400 includes the following components arranged in order from the object side to the image side: The optical system is composed of a first lens 401, an aperture stop SP, a second lens 402 having a first transmission-reflection surface HM1, a third lens 403, a fourth lens 404 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The second lens 402 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0093] FIG. 10 is a diagram showing aberrations when the imaging optical system 400 is focused at infinity, and is a diagram showing aberrations at wavelengths of the d-line, F-line, C-line, and g-line.

[0094] In this imaging optical system 400, focusing is performed by moving a first lens 401, a second lens 402, a third lens 403, and a fourth lens 404 together in the direction of the optical axis. [Example]

[0095] An imaging optical system 500 according to the fifth embodiment will be described with reference to FIG. 1 is a cross-sectional view of an imaging optical system 500. The imaging optical system 500 includes, arranged in order from the object side to the image side, a first lens 501, an aperture stop SP, a second lens 502 having a first transmission-reflection surface HM1, a third lens 503, and a fourth lens 504 having a second transmission-reflection surface HM2. The second lens 502 is made of a sensor protective glass GB. The second lens 502 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0096] FIG. 12 is a diagram showing aberrations of the imaging optical system 500 when focused at infinity, and is a diagram showing aberrations at wavelengths of the d-line, F-line, C-line, and g-line.

[0097] In this imaging optical system 500, focusing is performed by moving a first lens 501, a second lens 502, a third lens 503, and a fourth lens 504 together in the direction of the optical axis. [Example]

[0098] An imaging optical system 600 according to the sixth embodiment will be described with reference to FIG. This is a cross-sectional view of an imaging optical system 600. The imaging optical system 600 is composed of, arranged in order from the object side to the image side, a first lens 601, an aperture stop SP, a second lens 602, a third lens 603 having a first transmission-reflection surface HM1, a fourth lens 604, a fifth lens 605 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The third lens 603 also has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0099] FIG. 14 is a diagram showing aberrations of the imaging optical system 600 when focused at infinity, and shows aberrations of wavelengths of the d-line, F-line, C-line, and g-line.

[0100] In this imaging optical system 600, focusing is performed by moving a first lens 601, a second lens 602, a third lens 603, a fourth lens 604, and a fifth lens 605 together in the direction of the optical axis. [Example]

[0101] An imaging optical system 700 according to the seventh embodiment will be described with reference to FIG. This is a cross-sectional view of an imaging optical system 700. The imaging optical system 700 is composed of, arranged in order from the object side to the image side, a first lens 701 having a first transmission-reflection surface HM1, a second lens 702, a third lens 703 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The first lens 701 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0102] FIG. 16 is a diagram showing aberrations of the imaging optical system 700 when focused at infinity, and shows aberrations of wavelengths of the d-line, F-line, C-line, and g-line.

[0103] In this imaging optical system 700, focusing is performed by moving the first lens 701, second lens 702, and third lens 703 together in the optical axis direction. Focusing may also be performed by moving the third lens 703. [Example]

[0104] An imaging optical system 800 according to the eighth embodiment will be described with reference to FIG. This is a cross-sectional view of an imaging optical system 800. The imaging optical system 800 is composed of, arranged in order from the object side to the image side, a cemented lens formed by integrating a first lens 801 having a first transmission-reflection surface HM1 and a second lens 802 in this order, a third lens 803, a fourth lens 804 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The first lens 801 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0105] FIG. 18 is a diagram showing aberrations of the imaging optical system 800 when focused at infinity, and shows aberrations of wavelengths of the d-line, F-line, C-line, and g-line.

[0106] In this imaging optical system 800, focusing is performed by moving a first lens 801, a second lens 802, a third lens 803, and a fourth lens 804 together in the direction of the optical axis. [Example]

[0107] An imaging optical system 900 according to the ninth embodiment will be described with reference to FIG. This is a cross-sectional view of an imaging optical system 900. The imaging optical system 900 is composed of, arranged in order from the object side to the image side, a first lens 901, a second lens 902 having a first transmission-reflection surface HM1, a third lens 903, an aperture stop SP, and a fourth lens 904 having a second transmission-reflection surface HM2. The second lens 902 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0108] FIG. 20 is a diagram showing aberrations of the imaging optical system 900 when focused at infinity, and shows aberrations of wavelengths of the d-line, F-line, C-line, and g-line.

[0109] In this imaging optical system 900, focusing is performed by moving a first lens 901, a second lens 902, a third lens 903, and a fourth lens 904 together in the direction of the optical axis. [Example]

[0110] An imaging optical system 1000 according to Example 10 will be described with reference to Fig. 21. Fig. 21 is a cross-sectional view of the imaging optical system 1000. The imaging optical system 1000 includes, arranged in order from the object side to the image side, a first lens 1001 having a first transmitting-reflecting surface HM1, an aperture stop SP, and It is composed of a second lens 1002 and a third lens 1003 having a second transmission-reflection surface HM2. The first lens 1001 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0111] FIG. 22 shows aberration diagrams for the d-line, F-line, C-line, and g-line wavelengths when the focus is at infinity.

[0112] In this imaging optical system 1000, focusing is performed by moving the first lens 1001, the second lens 1002, and the third lens 1003 together in the direction of the optical axis. [Example]

[0113] An imaging optical system 1100 according to Example 11 will be described with reference to Fig. 23. Fig. 23 is a cross-sectional view of the imaging optical system 1100. The imaging optical system 1100 comprises the following components arranged in order from the object side to the image side: The optical system is composed of a first lens 1101 having a first transmission-reflection surface HM1, an aperture stop SP, a second lens 1102 having a second transmission-reflection surface HM2, and a sensor protection glass GB. The first lens 1101 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0114] FIG. 24 is a diagram showing aberrations when the imaging optical system 1100 is focused at infinity, and shows aberrations of wavelengths of the d-line, F-line, C-line, and g-line.

[0115] In this imaging optical system 1100, focusing is performed by moving the first lens 1101 and the second lens 1102 together in the direction of the optical axis. [Example]

[0116] An imaging optical system 1200 in Example 12 will be described with reference to Fig. 25. Fig. 235 is a cross-sectional view of the imaging optical system 1200. The imaging optical system 1200 is composed of, arranged in order from the object side to the image side, a first lens 1201, a second lens 1202 having a first transmission-reflection surface HM1, an aperture stop SP, a third lens 1203, and a fourth lens 1204 having a second transmission-reflection surface HM2. The second lens 1202 has a quarter-wave plate QWP on the image side of the first transmission-reflection surface HM1.

[0117] FIG. 26 shows aberration diagrams for the imaging optical system 1200 when focused at infinity, including the d-line, F-line, This is a wavelength aberration diagram for the C-line and g-line.

[0118] In this imaging optical system 1200, focusing is performed by moving a first lens 1201, a second lens 1202, a third lens 1203, and a fourth lens 1204 together in the direction of the optical axis.

[0119] Numerical Examples 1 to 12 corresponding to Examples 1 to 12, respectively, are shown below. In the surface data of each numerical example, surface number i indicates the ith surface in the order of the optical path from the object side. r is the radius of curvature of the ith surface (mm), d is the lens thickness or air gap (mm) between the ith and (i+1)th surfaces, and nd is the refractive index of the material of the ith optical component at the d-line. νd is the Abbe number based on the d-line of the material of the ith optical component. The Abbe number νd is expressed as νd = (Nd-1) / (NF-NC), where Nd, NF, and NC are the refractive indices at the Fraunhofer d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm). The refractive index and Abbe number are omitted for regions where the medium is air.

[0120] An asterisk (*) next to a surface number indicates that the surface has an aspherical shape. The aspherical shape is defined by the displacement in the optical axis direction at a position at a height h from the optical axis, with the vertex of the surface as the reference point, as x. When R is the paraxial radius of curvature, k is the conic constant, and Ai (i=2, 4, 6, 8, . . . ) are the aspheric coefficients of each order, it is expressed by the following formula.

[0121]

number

[0122] The effective diameter is described for the first transmissive-reflective surface and the second transmissive-reflective surface. At this time, these transmissive-reflective surfaces act on the light beam multiple times, and the diameter that is the largest effective diameter among these is described.

[0123] The various data include focal length (mm), F-number, half angle of view (°), image height (mm), etc. The total lens length here indicates the total length of the optical path before and after reflection by the optical surface. Meanwhile, the "distance on the optical axis" in each of the above-mentioned conditional expressions does not indicate the optical path length including the reflected optical path, but indicates the physical distance on the optical axis. (Numerical Example 1) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* -18.387 0.75 1.54658 55.9 2* -15.290 1.09 5.74 3* -8301.893 1.75 1.54658 55.9 4* 32.231 1.09 5* -12.715 -1.09 5.37 6* 32.231 -1.75 1.54658 55.9 7* -8301.893 -1.09 8* -15.290 1.09 9* -8301.893 1.75 1.54658 55.9 10* 32.231 1.09 11* -12.715 0.32 1.54658 55.9 12* 24.036 0.05 13 ∞ 0.20 1.51633 64.1 14 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2= 2.93156e-02 A 4=-2.44711e-04 A 6=-9.53633e-05 A 8= 3.71660e-07 2nd side K = 0.00000e+00 A 4=-1.19829e-03 A 6=-1.21820e-04 A 8= 6.09483e-06 A10=-1.20923e-07 3rd page K = 0.00000e+00 A 4=-4.35935e-03 A 6=-6.60834e-05 A 8=-1.18728e-06 A10= 1.31629e-06 A12=-4.73569e-08 Side 4 K = 0.00000e+00 A 4=-3.41190e-03 A 6= 1.89881e-05 A 8=-2.44660e-06 A10 = 6.47853e-07 Page 5 K = 0.00000e+00 A 4= 1.93169e-05 A 6=-1.00030e-05 A 8= 4.60648e-06 A10=-4.74183e-07 A12= 8.23996e-09 Page 6 K = 0.00000e+00 A 4=-3.41190e-03 A 6= 1.89881e-05 A 8=-2.44660e-06 A10 = 6.47853e-07 Page 7 K = 0.00000e+00 A 4=-4.35935e-03 A 6=-6.60834e-05 A 8=-1.18728e-06 A10= 1.31629e-06 A12=-4.73569e-08 Page 8 K = 0.00000e+00 A 4=-1.19829e-03 A 6=-1.21820e-04 A 8= 6.09483e-06 A10 = -1.20923e-07 Page 9 K = 0.00000e+00 A 4=-4.35935e-03 A 6=-6.60834e-05 A 8=-1.18728e-06 A10= 1.31629e-06 A12=-4.73569e-08 Page 10 K = 0.00000e+00 A 4=-3.41190e-03 A 6= 1.89881e-05 A 8=-2.44660e-06 A10 = 6.47853e-07 Page 11 K = 0.00000e+00 A 4= 1.93169e-05 A 6=-1.00030e-05 A 8= 4.60648e-06 A10=-4.74183e-07 A12= 8.23996e-09 Side 12 K = 0.00000e+00 A 2=-6.31717e-02 A 4=-2.01465e-02 A 6= 3.87149e-03 A 8=-2.23890e-04 Various data Focal length 10.27 F-number 1.80 Half angle of view (°) 14.73 Image height 2.70 Lens length 13.21 BF 0.10 d14 0.10 Entrance pupil position 0.00 Exit pupil position -7.82 Front principal point position -3.05 Back principal point position -10.17 Single lens data Lens starting surface focal length 1 1 26.30 2 3 -58.74 3 6 -58.74 4 9 -58.74 5 11 267.01 6 13 0.00 (Numerical Example 2) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* -22.719 0.89 1.54658 55.9 2* -12.674 2.06 8.50 3* -82.066 0.89 1.54658 55.9 4* 260.016 0.99 5* -28.026 -0.99 8.78 6* 260.016 -0.89 1.54658 55.9 7* -82.066 -2.06 8* -12.674 2.06 9* -82.066 0.89 1.54658 55.9 10* 260.016 0.99 11* -28.026 0.30 1.54658 55.9 12* 3.059 0.07 13 ∞ 0.20 1.51633 64.1 14 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2= 6.44766e-03 A 4=-2.00927e-03 A 6=-3.97094e-05 A 8=-3.63375e-10 2nd side K = 0.00000e+00 A 2= 5.44285e-03 A 4=-1.31498e-03 A 6=-5.55271e-05 A8=1.13341e-06 A10=-1.84643e-08 3rd page K = 0.00000e+00 A 4= 7.82567e-04 A 6=-1.40770e-04 A 8= 3.13547e-06 A10=-1.31494e-07 A12= 3.12347e-10 Side 4 K = 0.00000e+00 A 4= 3.11322e-04 A 6=-1.02677e-04 A 8= 1.74990e-06 A10=-1.75766e-08 5th page K = 0.00000e+00 A 2=-2.02253e-02 A 4=-1.15206e-04 A 6=-2.11799e-06 A 8= 5.06262e-07 A10=-3.28619e-08 A12= 5.43529e-10 Page 6 K = 0.00000e+00 A 4= 3.11322e-04 A 6=-1.02677e-04 A 8= 1.74990e-06 A10 = -1.75766e-08 Page 7 K = 0.00000e+00 A 4= 7.82567e-04 A 6=-1.40770e-04 A 8= 3.13547e-06 A10=-1.31494e-07 A12= 3.12347e-10 Page 8 K = 0.00000e+00 A 2= 5.44285e-03 A 4=-1.31498e-03 A 6=-5.55271e-05 A 8= 1.13341e-06 A10=-1.84643e-08 Page 9 K = 0.00000e+00 A 4= 7.82567e-04 A 6=-1.40770e-04 A 8= 3.13547e-06 A10=-1.31494e-07 A12= 3.12347e-10 Page 10 K = 0.00000e+00 A 4= 3.11322e-04 A 6=-1.02677e-04 A 8= 1.74990e-06 A10 = -1.75766e-08 Page 11 K = 0.00000e+00 A 2=-2.02253e-02 A 4=-1.15206e-04 A 6=-2.11799e-06 A 8= 5.06262e-07 A10=-3.28619e-08 A12= 5.43529e-10 Page 12 K = 0.00000e+00 A 2=-2.14048e-01 A 4=-5.68547e-03 A 6= 1.10815e-03 A 8=-1.66701e-04 Various data Zoom ratio 1.00 Focal length 10.59 F-number 1.30 Half angle of view (°) 14.30 Image height 2.70 Lens length 13.39 BF 0.10 d14 0.10 Entrance pupil position 4.39 Exit pupil position -6.95 Front principal point position -0.94 Back principal point position -10.49 Single lens data Lens starting surface focal length 1 1 48.71 2 3 -114.02 3 6 -114.02 4 9 -114.02 5 11 70.66 6 13 0.00 (Numerical Example 3) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* 3.914 0.74 1.54658 55.9 2* 15.583 1.58 3 (Aperture) ∞ 0.50 4* -13.030 0.51 1.54658 55.9 5 -10.033 1.24 6* -13.927 0.50 1.54658 55.9 7* -17.172 1.24 8 -9.966 -1.24 9* -17.172 -0.50 1.54658 55.9 10* -13.927 -1.24 11 -10.033 1.24 6.05 12* -13.927 0.50 1.54658 55.9 13* -17.172 1.24 14 -9.966 0.30 1.54658 55.9 7.57 15 -8.324 0.05 16 ∞ 0.24 1.51633 64.1 17 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2=-9.35147e-02 A 4=-7.52625e-03 A 6=-2.21557e-04 A8= 1.07810e-05 2nd side K = 0.00000e+00 A 4=-5.74115e-03 A 6=-8.84359e-05 A 8= 1.76716e-05 Side 4 K = 0.00000e+00 A 4= 4.10588e-04 A 6=-4.73325e-05 A 8= 4.02713e-06 Page 6 K = 0.00000e+00 A 4=-1.03372e-03 A 6= 2.09064e-04 A 8= 2.54380e-06 A10=-9.43289e-08 A12=-4.31995e-09 Side 7 K = 0.00000e+00 A 4=-5.62087e-04 A 6= 1.60507e-04 A 8= 8.13802e-07 A10=-1.76377e-09 9th page K = 0.00000e+00 A 4=-5.62087e-04 A 6= 1.60507e-04 A 8= 8.13802e-07 A10=-1.76377e-09 Side 10 K = 0.00000e+00 A 4=-1.03372e-03 A 6= 2.09064e-04 A 8= 2.54380e-06 A10=-9.43289e-08 A12=-4.31995e-09 Side 12 K = 0.00000e+00 A 4=-1.03372e-03 A 6= 2.09064e-04 A 8= 2.54380e-06 A10=-9.43289e-08 A12=-4.31995e-09 Page 13 K = 0.00000e+00 A 4=-5.62087e-04 A 6= 1.60507e-04 A 8= 8.13802e-07 A10=-1.76377e-09 Various data Zoom ratio 1.00 Focal length 8.47 F-number 1.60 Half angle of view (°) 26.36 Image height 4.20 Lens length 12.96 BF 0.10 d17 0.10 Entrance pupil position 2.13 Exit pupil position -7.62 Front principal point position 1.30 Back principal point position -8.37 Single lens data Lens starting surface focal length 1 1 337.90 2 4 75.23 3 6 -142.63 4 9 -142.63 5 12 -142.63 6 14 86.82 7 16 0.00 (Numerical Example 4) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* 68.386 0.80 1.54658 55.9 2* 7.172 0.50 3 (Aperture) ∞ 0.30 4* -13.308 0.67 1.54658 55.9 5* -9.143 1.35 5.43 6* -20.388 0.50 1.54658 55.9 7* -27.474 0.70 8* -8.603 -0.70 9* -27.474 -0.50 1.54658 55.9 10* -20.388 -1.35 11* -9.143 1.35 12* -20.388 0.50 1.54658 55.9 13* -27.474 0.70 14* -8.603 0.33 1.54658 55.9 6.36 15* -3.597 0.05 16 ∞ 0.20 1.51633 64.1 17 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2= 5.83310e-02 A 4=-4.68852e-03 A 6=-7.18937e-04 A8= 5.20323e-05 2nd side K = 0.00000e+00 A 4=-3.80340e-03 A 6=-8.66114e-04 A 8= 8.49003e-05 Side 4 K = 0.00000e+00 A 4= 2.52338e-03 A 6=-2.59547e-04 A 8= 1.40104e-05 Page 5 K = 0.00000e+00 A 4=-4.92829e-04 A 6=-3.13893e-05 A 8=-3.08591e-06 A10 = -5.51250e-07 Page 6 K = 0.00000e+00 A 4=-6.93674e-03 A 6= 6.41759e-04 A 8=-9.88404e-05 A10= 1.12955e-05 A12=-2.96339e-07 Page 7 K = 0.00000e+00 A 4=-5.75763e-03 A 6= 6.07633e-04 A 8=-7.35934e-05 A10 = 5.38917e-06 Page 8 K = 0.00000e+00 A 4= 2.32593e-04 A 6=-4.77838e-05 A 8= 4.51163e-06 A10= 2.68794e-07 A12=-4.53602e-08 Page 9 K = 0.00000e+00 A 4=-5.75763e-03 A 6= 6.07633e-04 A 8=-7.35934e-05 A10 = 5.38917e-06 Page 10 K = 0.00000e+00 A 4=-6.93674e-03 A 6= 6.41759e-04 A 8=-9.88404e-05 A10= 1.12955e-05 A12=-2.96339e-07 Page 11 K = 0.00000e+00 A 4=-4.92829e-04 A 6=-3.13893e-05 A 8=-3.08591e-06 A10 = -5.51250e-07 Page 12 K = 0.00000e+00 A 4=-6.93674e-03 A 6= 6.41759e-04 A 8=-9.88404e-05 A10= 1.12955e-05 A12=-2.96339e-07 Page 13 K = 0.00000e+00 A 4=-5.75763e-03 A 6= 6.07633e-04 A 8=-7.35934e-05 A10= 5.38917e-06 Side 14 K = 0.00000e+00 A 4= 2.32593e-04 A 6=-4.77838e-05 A 8= 4.51163e-06 A10=2.68794e-07 A12=-4.53602e-08 Page 15 K = 0.00000e+00 A 2= 5.07013e-02 A 4= 9.71519e-03 A 6=-5.83288e-04 A 8= 2.09748e-05 Various data Zoom ratio 1.00 Focal length 7.21 F-number 1.40 Half angle of view (°) 25.90 Image height 3.50 Lens length 10.60 BF 0.10 d17 0.10 Entrance pupil position 1.08 Exit pupil position -7.76 Front principal point position 1.67 Back principal point position -7.11 Single lens data Lens starting surface focal length 1 1 -612.98 2 4 50.58 3 6 -148.32 4 9 -148.32 5 12 -148.32 6 14 29.14 7 16 0.00 (Numerical Example 5) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* 5.166 0.50 1.54658 55.9 2* -227.218 0.20 3 (Aperture) ∞ 1.53 4* -4.855 0.52 1.54658 55.9 5* -6.356 0.89 6* -5.135 0.50 1.54658 55.9 7* -5.533 0.72 8* -6.902 -0.72 6.24 9* -5.533 -0.50 1.54658 55.9 10* -5.135 -0.89 11* -6.356 0.89 7.00 12* -5.135 0.50 1.54658 55.9 13* -5.533 0.72 14* -6.902 0.30 1.54658 55.9 15* -4.854 0.04 16 ∞ 0.20 1.51633 64.1 17 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2=-7.03524e-02 A 4=-1.39437e-02 A 6=-9.52179e-04 A8=-3.90902e-05 A10= 2.66067e-06 A12= 1.31574e-08 2nd side K = 0.00000e+00 A 4=-1.49638e-02 A 6=-8.77799e-04 A 8= 1.03612e-04 A10=-1.00467e-05 A12= 7.47849e-07 Page 4 K = 0.00000e+00 A 4=-6.80839e-03 A 6= 4.69122e-04 A 8= 8.21024e-05 Page 5 K = 0.00000e+00 A 4=-2.32860e-03 A 6= 2.20307e-04 A 8= 4.54969e-06 A10 = -5.17761e-07 Page 6 K = 0.00000e+00 A 4= 8.72885e-03 A 6=-6.45244e-04 A 8=-2.44843e-05 A10= 5.63144e-06 A12=-1.87955e-07 Page 7 K = 0.00000e+00 A 4= 5.50577e-03 A 6=-2.62192e-04 A 8=-1.37424e-05 A10 = 1.11199e-06 Page 8 K = 0.00000e+00 A 4=-3.18341e-05 A 6= 1.78016e-05 A 8=-4.11465e-06 A10= 6.26657e-07 A12=-1.73006e-08 Page 9 K = 0.00000e+00 A 4= 5.50577e-03 A 6=-2.62192e-04 A 8=-1.37424e-05 A10 = 1.11199e-06 Page 10 K = 0.00000e+00 A 4= 8.72885e-03 A 6=-6.45244e-04 A 8=-2.44843e-05 A10=5.63144e-06 A12=-1.87955e-07 Page 11 K = 0.00000e+00 A 4=-2.32860e-03 A 6= 2.20307e-04 A 8= 4.54969e-06 A10=-5.17761e-07 Side 12 K = 0.00000e+00 A 4= 8.72885e-03 A 6=-6.45244e-04 A 8=-2.44843e-05 A10=5.63144e-06 A12=-1.87955e-07 Page 13 K = 0.00000e+00 A 4= 5.50577e-03 A 6=-2.62192e-04 A 8=-1.37424e-05 A10= 1.11199e-06 Side 14 K = 0.00000e+00 A 4=-3.18341e-05 A 6= 1.78016e-05 A 8=-4.11465e-06 A10=6.26657e-07 A12=-1.73006e-08 Page 15 K = 0.00000e+00 A 2= 5.50201e-02 A 4= 9.90886e-03 A 6=-5.77224e-04 A 8= 1.23735e-05 Various data Zoom ratio 1.00 Focal length 6.20 F-number 1.80 Half angle of view (°) 29.44 Image height 3.50 Lens length 9.72 BF 0.10 d17 0.10 Entrance pupil position 0.53 Exit pupil position -5.52 Front principal point position -0.11 Back principal point position -6.10 Zoom lens group data Group Starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 6.20 5.40 -0.11 -6.10 Single lens data Lens starting surface focal length 1 1 31.96 2 4 -42.81 3 6 -235.28 4 9 -235.28 5 12 -235.28 6 14 -38.54 7 16 0.00 (Numerical Example 6) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* 6.834 1.74 1.54658 55.9 2* 16.378 3.81 3 (Aperture) ∞ 0.88 4* -14.196 1.71 1.54658 55.9 5* 301.447 0.63 6* -11.034 0.30 1.54658 55.9 7* -9.238 0.96 8* -17.165 0.88 1.54658 55.9 9* -12.889 0.82 10* -9.043 -0.82 11* -12.889 -0.88 1.54658 55.9 12* -17.165 -0.96 13* -9.238 0.96 9.60 14* -17.165 0.88 1.54658 55.9 15* -12.889 0.82 16* -9.043 0.56 1.54658 55.9 12.37 17* -7.283 0.05 18 ∞ 0.43 1.51633 64.1 19 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2=-2.76193e-02 A 4=-1.48482e-04 A 6=-3.44041e-07 A8= 4.05757e-09 A10=-1.32702e-10 A12= 7.47796e-13 2nd side K = 0.00000e+00 A 4= 2.35488e-04 A 6= 5.10752e-06 A 8=-5.19375e-08 A10=4.95941e-09 A12=-8.12477e-11 Side 4 K = 0.00000e+00 A 4=-1.40363e-03 A 6=-2.20005e-07 A 8=-7.57564e-07 A10= 2.69338e-08 5th page K = 0.00000e+00 A 4=-8.83456e-04 A 6= 6.59973e-06 A 8=-6.72884e-07 Page 6 K = 0.00000e+00 A 4=-8.94061e-04 A 6= 6.01317e-06 A 8=-1.92247e-06 Side 7 K = 0.00000e+00 A 4=-4.09096e-04 A 6= 2.80743e-06 A 8=-2.80466e-07 A10= 1.11480e-08 Side 8 K = 0.00000e+00 A 4= 2.59434e-04 A 6=-2.40538e-05 A 8= 8.94418e-07 A10=-1.99380e-08 A12= 9.77907e-11 Page 9 K = 0.00000e+00 A 4= 1.36420e-04 A 6=-2.18568e-05 A 8= 7.88464e-07 A10 = -1.32052e-08 Page 10 K = 0.00000e+00 A 4=-6.16694e-05 A 6= 3.13305e-06 A 8=-9.19933e-08 A10=-9.29122e-10 A12= 5.19478e-11 Page 11 K = 0.00000e+00 A 4= 1.36420e-04 A 6=-2.18568e-05 A 8= 7.88464e-07 A10 = -1.32052e-08 Page 12 K = 0.00000e+00 A 4= 2.59434e-04 A 6=-2.40538e-05 A 8= 8.94418e-07 A10=-1.99380e-08 A12= 9.77907e-11 Page 13 K = 0.00000e+00 A 4=-4.09096e-04 A 6= 2.80743e-06 A 8=-2.80466e-07 A10 = 1.11480e-08 Page 14 K = 0.00000e+00 A 4= 2.59434e-04 A 6=-2.40538e-05 A 8= 8.94418e-07 A10=-1.99380e-08 A12= 9.77907e-11 Page 15 K = 0.00000e+00 A 4= 1.36420e-04 A 6=-2.18568e-05 A 8= 7.88464e-07 A10 = -1.32052e-08 Page 16 K = 0.00000e+00 A 4=-6.16694e-05 A 6= 3.13305e-06 A 8=-9.19933e-08 A10=-9.29122e-10 A12= 5.19478e-11 Page 17 K = 0.00000e+00 A 2= 2.20836e-02 A 4= 1.76117e-03 A 6=-3.85080e-05 A8= 1.93218e-07 Various data Zoom ratio 1.00 Focal length 7.80 F-number 1.40 Half angle of view (°) 45.43 Image height 7.92 Lens length 18.18 BF 0.10 d19 0.10 Entrance pupil position 5.80 Exit pupil position -10.35 Front principal point position 7.78 Back principal point position -7.70 Single lens data Lens starting surface focal length 1 1 54.70 2 4 -24.76 3 6 98.04 4 8 88.27 5 11 88.27 6 14 88.27 7 16 -118.86 8 18 0.00 (Numerical Example 7) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* 8.971 0.51 1.54658 55.9 2* -13.788 1.92 5.84 3* 11.942 0.72 1.54658 55.9 4* 9.720 1.27 5* 33.053 0.30 1.54658 55.9 6* -13.481 -0.30 5.73 7* 33.053 -1.27 8* 9.720 -0.72 1.54658 55.9 9* 11.942 -1.92 10* -13.788 1.92 11* 11.942 0.72 1.54658 55.9 12* 9.720 1.27 13* 33.053 0.30 1.54658 55.9 14* -13.481 0.44 15 ∞ 0.10 1.51633 64.1 16 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2=-7.91546e-02 A 4=-1.36693e-03 A 6=-2.46324e-05 A 8=-2.09970e-06 2nd side K = 0.00000e+00 A 4=-1.07656e-03 A 6=-3.90324e-05 A 8=-6.35705e-07 A10=-4.59773e-08 3rd page K = 0.00000e+00 A 4=-2.72817e-03 A 6=-4.29541e-04 A 8= 5.58439e-06 A10=9.86298e-07 A12=-8.89788e-08 Side 4 K = 0.00000e+00 A 4=-1.98197e-03 A 6=-5.38358e-04 A 8= 7.88237e-06 A10 = 2.92046e-07 Page 5 K = 0.00000e+00 A 2=-4.96450e-02 A 4= 6.33648e-04 A 6= 5.09842e-05 A 8=-1.67185e-05 A10=-9.37608e-07 A12= 7.64872e-08 Page 6 K = 0.00000e+00 A 4=-4.16257e-05 A 6= 3.80574e-05 A 8=-3.61205e-06 Page 7 K = 0.00000e+00 A 2=-4.96450e-02 A 4= 6.33648e-04 A 6= 5.09842e-05 A 8=-1.67185e-05 A10=-9.37608e-07 A12= 7.64872e-08 Page 8 K = 0.00000e+00 A 4=-1.98197e-03 A 6=-5.38358e-04 A 8= 7.88237e-06 A10 = 2.92046e-07 Page 9 K = 0.00000e+00 A 4=-2.72817e-03 A 6=-4.29541e-04 A 8= 5.58439e-06 A10= 9.86298e-07 A12=-8.89788e-08 Page 10 K = 0.00000e+00 A 4=-1.07656e-03 A 6=-3.90324e-05 A 8=-6.35705e-07 A10 = -4.59773e-08 Page 11 K = 0.00000e+00 A 4=-2.72817e-03 A 6=-4.29541e-04 A 8= 5.58439e-06 A10=9.86298e-07 A12=-8.89788e-08 Side 12 K = 0.00000e+00 A 4=-1.98197e-03 A 6=-5.38358e-04 A 8= 7.88237e-06 A10= 2.92046e-07 Page 13 K = 0.00000e+00 A 2=-4.96450e-02 A 4= 6.33648e-04 A 6= 5.09842e-05 A8=-1.67185e-05 A10=-9.37608e-07 A12=7.64872e-08 Side 14 K = 0.00000e+00 A 4=-4.16257e-05 A 6= 3.80574e-05 A 8=-3.61205e-06 Various data Zoom ratio 1.00 Focal length 11.52 F-number 2.00 Half angle of view (°) 13.19 Image height 2.70 Lens length 13.76 BF 0.10 d16 0.10 Entrance pupil position 0.00 Exit pupil position -8.58 Front principal point position -3.78 Back principal point position -11.42 Single lens data Lens starting surface focal length 1 1 69.57 2 3 -107.93 3 5 321.77 4 6 321.77 5 8 -107.93 6 11 -107.93 7 13 321.77 8 15 0.00 (Numerical Example 8) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* 53.826 1.23 1.54658 55.9 2* -15.124 1.47 1.54658 55.9 8.62 3* 7.123 1.50 4* -43.348 0.50 1.54658 55.9 5* 37.381 0.70 6* -13.133 -0.70 8.41 7* 37.381 -0.50 1.54658 55.9 8* -43.348 -1.50 9* 7.123 -1.47 1.54658 55.9 10* -15.124 1.47 11* 7.123 1.50 12* -43.348 0.50 1.54658 55.9 13* 37.381 0.70 14* -13.133 0.25 1.54658 55.9 15* 3.332 0.05 16 ∞ 0.20 1.51633 64.1 17 ∞ (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 2= 2.78605e-03 A 4=-7.25744e-04 A 6=-7.51303e-07 A 8=-1.74988e-07 2nd side K = 0.00000e+00 A 4=-1.43237e-03 A 6=-4.13680e-05 A 8=-8.70457e-06 A10 = 5.72952e-07 Page 3 K = 0.00000e+00 A 2=-1.04474e-01 A 4=-1.19801e-03 A 6= 2.88680e-05 A 8=-1.49038e-06 A10= 1.78478e-08 Page 4 K = 0.00000e+00 A 4=-3.80060e-03 A 6= 2.50706e-04 A 8=-1.42146e-05 A10= 2.21897e-07 A12= 9.88712e-10 Page 5 K = 0.00000e+00 A 4=-3.70781e-03 A 6= 1.97247e-04 A 8=-9.83150e-06 A10 = 1.76891e-07 Page 6 K = 0.00000e+00 A 4=-5.34069e-05 A 6= 2.02098e-05 A 8=-2.25255e-06 A10= 1.01424e-07 A12=-1.76046e-09 Page 7 K = 0.00000e+00 A 4=-3.70781e-03 A 6= 1.97247e-04 A 8=-9.83150e-06 A10 = 1.76891e-07 Page 8 K = 0.00000e+00 A 4=-3.80060e-03 A 6= 2.50706e-04 A 8=-1.42146e-05 A10= 2.21897e-07 A12= 9.88712e-10 Page 9 K = 0.00000e+00 A 2=-1.04474e-01 A 4=-1.19801e-03 A 6= 2.88680e-05 A 8=-1.49038e-06 A10= 1.78478e-08 Page 10 K = 0.00000e+00 A 4=-1.43237e-03 A 6=-4.13680e-05 A 8=-8.70457e-06 A10= 5.72952e-07 Page 11 K = 0.00000e+00 A 2=-1.04474e-01 A 4=-1.19801e-03 A 6= 2.88680e-05 A8=-1.49038e-06 A10=1.78478e-08 Side 12 K = 0.00000e+00 A 4=-3.80060e-03 A 6= 2.50706e-04 A 8=-1.42146e-05 A10= 2.21897e-07 A12= 9.88712e-10 Page 13 K = 0.00000e+00 A 4=-3.70781e-03 A 6= 1.97247e-04 A 8=-9.83150e-06 A10= 1.76891e-07 Side 14 K = 0.00000e+00 A 4=-5.34069e-05 A 6= 2.02098e-05 A 8=-2.25255e-06 A10= 1.01424e-07 A12=-1.76046e-09 Page 15 K = 0.00000e+00 A 2=-2.31030e-01 A 4=-2.51324e-03 A 6= 4.11608e-04 A 8=-7.78731e-05 Various data Zoom ratio 1.00 Focal length 10.88 F-number 1.27 Half angle of view (°) 13.93 Image height 2.70 Lens length 14.35 BF 0.10 d17 0.10 Entrance pupil position 0.00 Exit pupil position -11.46 Front principal point position 0.64 Back principal point position -10.78 Single lens data Lens starting surface focal length 1 1 20.42 2 2 381.42 3 4 -36.64 4 7 -36.64 5 9 381.42 6 10 381.42 7 12 -36.64 8 14 21.07 9 16 0.00 (Numerical Example 9) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 ∞ 3.00 1.51633 64.1 2* -1434.771 14.15 3* -41.770 2.00 1.51633 64.1 4* -99.590 10.42 68.73 5* -153.014 5.00 1.51633 64.1 6* -100.989 1.00 7 (Aperture) ∞ 9.42 8* -99.468 -10.42 77.86 9* -100.989 -5.00 1.51633 64.1 10* -153.014 -10.42 11* -99.590 10.42 12* -153.014 5.00 1.51633 64.1 13* -100.989 10.42 14* -99.468 2.00 1.63000 23.0 15* -24.734 (variable) Image plane ∞ Aspheric data 2nd side K = 0.00000e+00 A 4= 1.69907e-06 A 6= 2.45484e-10 A 8= 9.28970e-14 3rd page K = 0.00000e+00 A 2= 4.34450e-03 A 4= 2.18108e-06 A 6=-7.80950e-10 A8=-7.12257e-15 A10=7.10332e-17 Side 4 K = 0.00000e+00 A 4=-4.67132e-07 A 6=-7.88299e-10 A 8=-1.27088e-13 5th page K = 0.00000e+00 A 4=-3.13196e-07 A 6= 5.03601e-10 Page 6 K = 0.00000e+00 A 4=-5.55144e-07 A 6= 5.69192e-10 Side 8 K = 0.00000e+00 A 4= 8.19095e-08 A 6=-1.48267e-10 A 8= 1.14673e-14 9th page K = 0.00000e+00 A 4=-5.55144e-07 A 6= 5.69192e-10 Side 10 K = 0.00000e+00 A 4=-3.13196e-07 A 6= 5.03601e-10 Page 11 K = 0.00000e+00 A 4=-4.67132e-07 A 6=-7.88299e-10 A 8=-1.27088e-13 Side 12 K = 0.00000e+00 A 4=-3.13196e-07 A 6= 5.03601e-10 Page 13 K = 0.00000e+00 A 4=-5.55144e-07 A 6= 5.69192e-10 Side 14 K = 0.00000e+00 A 4= 8.19095e-08 A 6=-1.48267e-10 A 8= 1.14673e-14 Page 15 K = 0.00000e+00 A 2= 1.79319e-02 A 4= 1.06521e-05 A 6= 2.74699e-09 A 8= 1.71134e-11 Various data Zoom ratio 1.00 Focal length 85.00 F-number 1.30 Half angle of view (°) 14.28 Image height 21.64 Lens length 116.69 BF 18.00 d15 18.00 Entrance pupil position 31.58 Exit pupil position -42.85 Front principal point position -2.14 Back principal point position -67.00 Single lens data Lens starting surface focal length 1 1 2778.79 2 3 -379.29 3 5 557.03 4 9 557.03 5 12 557.03 6 14 -291.18 (Numerical Example 10) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* -43.660 1.80 1.51633 64.1 2* -29.645 0.00 24.13 3 (Aperture) ∞ 6.75 4* -17.570 3.94 1.51633 64.1 5* -22.957 6.75 6* -49.963 -6.75 26.22 7* -22.957 -3.94 1.51633 64.1 8* -17.570 -6.75 9* -29.645 6.75 10* -17.570 3.94 1.51633 64.1 11* -22.957 6.75 12* -49.963 1.50 1.49700 81.5 13* -5.903 (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 4=-3.13162e-05 A 6= 2.05836e-07 A 8= 2.98848e-12 2nd side K = 0.00000e+00 A 4=-3.45367e-05 A 6= 2.43905e-07 Side 4 K = 0.00000e+00 A 4=-4.30902e-05 A 6= 1.64429e-07 5th page K = 0.00000e+00 A 4=-2.24284e-05 A 6= 3.63609e-08 Page 6 K = 0.00000e+00 A 4=-2.25614e-06 A 6= 1.02617e-08 A 8=-1.71753e-11 Side 7 K = 0.00000e+00 A 4=-2.24284e-05 A 6= 3.63609e-08 Side 8 K = 0.00000e+00 A 4=-4.30902e-05 A 6= 1.64429e-07 9th page K = 0.00000e+00 A 4=-3.45367e-05 A 6= 2.43905e-07 Side 10 K = 0.00000e+00 A 4=-4.30902e-05 A 6= 1.64429e-07 Page 11 K = 0.00000e+00 A 4=-2.24284e-05 A 6= 3.63609e-08 Side 12 K = 0.00000e+00 A 4=-2.25614e-06 A 6= 1.02617e-08 A 8=-1.71753e-11 Page 13 K = 0.00000e+00 A 2= 9.42718e-02 A 4= 7.17789e-04 A 6= 1.90716e-05 A8= 6.74039e-07 Various data Zoom ratio 1.00 Focal length 60.00 F-number 2.50 Half angle of view (°) 4.14 Image height 4.34 Lens length 56.85 BF 1.27 d13 1.27 Entrance pupil position 1.17 Exit pupil position -18.83 Front principal point position -117.87 Back principal point position -58.73 Single lens data Lens starting surface focal length 1 1 171.37 2 4 -193.03 3 7 -193.03 4 10 -193.03 5 12 -51.15 (Numerical Example 11) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1* -43.660 1.80 1.51633 64.1 2* -29.645 0.00 24.13 3 (Aperture) ∞ 6.75 4* -17.570 3.94 1.51633 64.1 23.59 5* -22.957 6.75 6* -49.963 -6.75 7* -22.957 -3.94 1.51633 64.1 8* -17.570 -6.75 9* -29.645 6.75 10* -17.570 3.94 1.51633 64.1 11* -22.957 6.75 12* -49.963 1.50 1.49700 81.5 13* -5.903 (variable) Image plane ∞ Aspheric data Front page K = 0.00000e+00 A 4=-3.13162e-05 A 6= 2.05836e-07 A 8= 2.98848e-12 2nd side K = 0.00000e+00 A 4=-3.45367e-05 A 6= 2.43905e-07 Side 4 K = 0.00000e+00 A 4=-4.30902e-05 A 6= 1.64429e-07 5th page K = 0.00000e+00 A 4=-2.24284e-05 A 6= 3.63609e-08 Page 6 K = 0.00000e+00 A 4=-2.25614e-06 A 6= 1.02617e-08 A 8=-1.71753e-11 Side 7 K = 0.00000e+00 A 4=-2.24284e-05 A 6= 3.63609e-08 Side 8 K = 0.00000e+00 A 4=-4.30902e-05 A 6= 1.64429e-07 9th page K = 0.00000e+00 A 4=-3.45367e-05 A 6= 2.43905e-07 Side 10 K = 0.00000e+00 A 4=-4.30902e-05 A 6= 1.64429e-07 Page 11 K = 0.00000e+00 A 4=-2.24284e-05 A 6= 3.63609e-08 Side 12 K = 0.00000e+00 A 4=-2.25614e-06 A 6= 1.02617e-08 A 8=-1.71753e-11 Page 13 K = 0.00000e+00 A 2= 9.42718e-02 A 4= 7.17789e-04 A 6= 1.90716e-05 A8= 6.74039e-07 Various data Zoom ratio 1.00 Focal length 60.00 F-number 2.50 Half angle of view (°) 4.14 Image height 4.34 Lens length 56.85 BF 1.27 d13 1.27 Entrance pupil position 1.17 Exit pupil position -18.83 Front principal point position -117.87 Back principal point position -58.73 Single lens data Lens starting surface focal length 1 1 171.37 2 4 -193.03 3 7 -193.03 4 10 -193.03 5 12 -51.15 (Numerical Example 12) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 ∞ 2.00 1.51633 64.1 2* -220.765 10.83 3* -48.226 12.25 1.51633 64.1 4* -90.765 0.00 67.74 5 (Aperture) ∞ 6.85 6* -114.978 5.00 1.51633 64.1 7* -84.663 6.85 8* -89.921 -6.85 71.34 9* -84.663 -5.00 1.51633 64.1 10* -114.978 -6.85 11* -90.765 6.85 12* -114.978 5.00 1.51633 64.1 13* -84.663 6.85 14* -89.921 5.55 1.63000 23.0 15* -26.894 (variable) Image plane ∞ Aspheric data 2nd side K = 0.00000e+00 A 4= 2.62580e-06 A 6=-1.15117e-10 A 8= 3.59052e-14 Page 3 K = 0.00000e+00 A 2= 1.28550e-03 A 4= 3.33294e-06 A 6=-2.69495e-09 A 8= 7.26662e-13 A10= 3.26603e-17 Page 4 K = 0.00000e+00 A 4= 5.86678e-08 A 6=-1.43048e-09 A 8= 5.92180e-13 Page 6 K = 0.00000e+00 A 4= 1.99021e-06 A 6= 5.49028e-10 Page 7 K = 0.00000e+00 A 4= 1.52785e-06 A 6= 8.65881e-10 Page 8 K = 0.00000e+00 A 4= 1.19765e-07 A 6=-1.92249e-10 A 8=-1.57989e-14 Page 9 K = 0.00000e+00 A 4= 1.52785e-06 A 6= 8.65881e-10 Page 10 K = 0.00000e+00 A 4= 1.99021e-06 A 6= 5.49028e-10 Page 11 K = 0.00000e+00 A 4= 5.86678e-08 A 6=-1.43048e-09 A 8= 5.92180e-13 Page 12 K = 0.00000e+00 A 4= 1.99021e-06 A 6= 5.49028e-10 Page 13 K = 0.00000e+00 A 4= 1.52785e-06 A 6= 8.65881e-10 Page 14 K = 0.00000e+00 A 4= 1.19765e-07 A 6=-1.92249e-10 A 8=-1.57989e-14 Page 15 K = 0.00000e+00 A 2= 1.57692e-02 A 4= 8.16452e-06 A 6= 1.74427e-09 A 8= 9.01082e-12 Various data Zoom ratio 1.00 Focal length 85.00 F-number 1.40 Half angle of view (°) 14.28 Image height 21.64 Lens length 117.40 BF 30.67 d15 30.67 Entrance pupil position 20.48 Exit pupil position -41.86 Front principal point position 5.86 Back principal point position -54.33 Single lens data Lens starting surface focal length 1 1 427.56 2 3 -306.82 3 6 588.84 4 9 588.84 5 12 588.84 6 14 -297.19 Table 1 shows the values ​​of the conditional expressions in each example.

[0124] [Table 1]

[0125] The imaging optical system of each embodiment can be used in imaging devices such as smartphone imaging cameras, distance detection cameras, fixed-lens cameras, and disposable film cameras that have an imaging element that receives an image formed by the imaging optical system. The imaging optical system of each embodiment can also be used in interchangeable lenses for interchangeable-lens cameras. It may also be used in camera viewfinders and XR devices for, for example, line-of-sight detection, biometric recognition, and facial expression recognition. It may also be used for external environment recognition applications such as XR devices and automatic robots.

[0126] The disclosure of each embodiment includes the following configuration.

[0127] (Configuration 1) An optical system having a first transmissive-reflective surface, a quarter-wave plate, and a second transmissive-reflective surface arranged in this order from an object side to an image side, the optical system is a primary imaging system, light from the object side passes through the first transmission-reflection surface and the quarter-wave plate in this order, is reflected by the second transmission-reflection surface toward the object side, passes through the quarter-wave plate, is reflected by the first transmission-reflection surface toward the image side, passes through the quarter-wave plate and the second transmission-reflection surface in this order, and proceeds toward the image side; When the distance on the optical axis from the first transmissive-reflective surface to the image plane is zm1 and the focal length of the optical system is f, 0.10≦zm1 / f≦0.68 An optical system characterized by satisfying the following conditional expression: (Configuration 2) Let La be the distance on the optical axis from the lens surface closest to the object to the image plane, h be the radius of the image circle, and F-number be Fno. 0.0≦La×h×Fno / f2≦2.6 The optical system according to configuration 1, characterized in that the following condition is satisfied: (Configuration 3) Let La be the distance on the optical axis from the lens surface closest to the object to the image plane, and h be the radius of the image circle. 0.0≦La×h / f2≦2.0 3. The optical system according to configuration 1 or 2, wherein the following condition is satisfied: (Configuration 4) When the diameter of the first transmitting-reflecting surface is Φm1 and the diameter of the second transmitting-reflecting surface is Φm2, 0.50≦Φm1 / Φm2≦1.25 4. The optical system according to any one of configurations 1 to 3, wherein the following condition is satisfied: (Configuration 5) When the radius of the image circle is h, the F-number is Fno, and the diameter of the second transmissive-reflective surface is Φm2, 0.1≦h / (Φm2 / 2) / Fno≦1.2 5. The optical system according to any one of configurations 1 to 4, wherein the following condition is satisfied: (Configuration 6) The distance on the optical axis from the lens surface closest to the object to the image plane is La. When the distance on the optical axis from the second transmissive-reflective surface to the image plane is zm2, 0.0≦zm2 / La≦0.5 6. The optical system according to any one of configurations 1 to 5, wherein the following condition is satisfied: (Configuration 7) When the absolute value of the refractive power of the lens including the second transmissive-reflective surface is Φm1L, 0.0≦Φm1L×f≦1.0 7. The optical system according to any one of configurations 1 to 6, wherein the following condition is satisfied: (Configuration 8) When the average value of the absolute values ​​of the refractive powers of the lenses included in the optical system is AΦr, and the average value of the absolute values ​​of the refractive powers of the first transmissive-reflective surface and the second transmissive-reflective surface is AΦm, 0.0≦AΦr / AΦm≦0.5 8. The optical system according to any one of configurations 1 to 7, wherein the following condition is satisfied: (Configuration 9) 9. The optical system according to any one of configurations 1 to 8, wherein one of the first and second transmission-reflection surfaces separates incident light into reflected light and transmitted light according to its polarization state. (Configuration 10) 10. The optical system according to configuration 9, wherein the other of the first and second transmitting-reflecting surfaces is a half mirror. (Configuration 11) 11. The optical system according to any one of configurations 1 to 10, wherein the shape of the effective area of ​​each of the plurality of lens surfaces included in the optical system is rotationally symmetric with respect to the optical axis. (Configuration 12) 12. The optical system according to any one of configurations 1 to 11, further comprising an aperture stop. (Configuration 13) When the distance on the optical axis from the aperture stop to the image plane is zp, 0.1≦zp / f≦1.2 13. The optical system according to configuration 12, wherein the following condition is satisfied: (Configuration 14) When the F-number is Fno, 0.5≦Fno≦8.0 14. The optical system according to any one of configurations 1 to 13, wherein the following condition is satisfied: (Configuration 15) 15. The optical system according to any one of configurations 1 to 14, wherein at least one of the first and second transmission-reflection surfaces is a flat surface. (Configuration 16) In the wavelength band used, when the element in the second row and second column of the Mueller matrix corresponding to the quarter-wave plate is a22 and the element in the third row and second column is a32, -0.25≦a22≦0.25 -0.25≦a32≦0.25 16. The optical system according to any one of configurations 1 to 15, wherein the following condition is satisfied: (Configuration 17) 0.10≦zm1 / f≦0.55 17. The optical system according to any one of configurations 1 to 16, wherein the following condition is satisfied: (Configuration 18) 18. An imaging device comprising: the optical system according to any one of configurations 1 to 17; and an imaging element that receives an image formed by the optical system.

[0128] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0129] Imaging optical system 100 First transflective surface HM1 1 / 4 wavelength plate QWP Second transflective surface HM2

Claims

1. An optical system having a first transmissive-reflective surface, a quarter-wave plate, and a second transmissive-reflective surface arranged in this order from an object side to an image side, the optical system is a primary imaging system, light from the object side passes through the first transmission-reflection surface and the quarter-wave plate in this order, is reflected by the second transmission-reflection surface toward the object side, passes through the quarter-wave plate, is reflected by the first transmission-reflection surface toward the image side, passes through the quarter-wave plate and the second transmission-reflection surface in this order, and proceeds toward the image side; When the distance on the optical axis from the first transmissive-reflective surface to the image plane is zm1 and the focal length of the optical system is f, 0.10≦zm1 / f≦0.68 An optical system characterized by satisfying the following conditional expression:

2. Let La be the distance on the optical axis from the lens surface closest to the object to the image plane, h be the radius of the image circle, and F-number Fno be: 0.0≦La×h×Fno / f2≦2.6 2. The optical system according to claim 1, wherein the following condition is satisfied:

3. Let La be the distance on the optical axis from the lens surface closest to the object to the image plane, and h be the radius of the image circle. 0.0≦La×h / f2≦2.0 2. The optical system according to claim 1, wherein the following condition is satisfied:

4. When the diameter of the first transmitting-reflecting surface is Φm1 and the diameter of the second transmitting-reflecting surface is Φm2, 0.50≦Φm1 / Φm2≦1.25 2. The optical system according to claim 1, wherein the following condition is satisfied:

5. When the radius of the image circle is h, the F-number is Fno, and the diameter of the second transmissive-reflective surface is Φm2, 0.1≦h / (Φm2 / 2) / Fno≦1.2 2. The optical system according to claim 1, wherein the following condition is satisfied:

6. The distance on the optical axis from the lens surface closest to the object to the image plane is La, When the distance on the optical axis from the second transmissive-reflective surface to the image plane is zm2, 0.0≦zm2 / La≦0.5 2. The optical system according to claim 1, wherein the following condition is satisfied:

7. When the absolute value of the refractive power of the lens including the second transmissive-reflective surface is Φm1L, 0.0≦Φm1L×f≦1.0 2. The optical system according to claim 1, wherein the following condition is satisfied:

8. When the average value of the absolute values ​​of the refractive powers of the lenses included in the optical system is AΦr, and the average value of the absolute values ​​of the refractive powers of the first transmissive-reflective surface and the second transmissive-reflective surface is AΦm, 0.0≦AΦr / AΦm≦0.5 2. The optical system according to claim 1, wherein the following condition is satisfied:

9. 2. The optical system according to claim 1, wherein one of the first and second transmission-reflection surfaces separates incident light into reflected light and transmitted light according to a polarization state.

10. 10. The optical system according to claim 9, wherein the other of the first and second transmissive-reflective surfaces is a half mirror.

11. 2. The optical system according to claim 1, wherein the shape of the effective area of ​​each of the plurality of lens surfaces included in said optical system is rotationally symmetric with respect to the optical axis.

12. 2. The optical system of claim 1, further comprising an aperture stop.

13. When the distance on the optical axis from the aperture stop to the image plane is zp, 0.1≦zp / f≦1.2 13. The optical system according to claim 12, wherein the following condition is satisfied:

14. When the F-number is Fno, 0.5≦Fno≦8.0 2. The optical system according to claim 1, wherein the following condition is satisfied:

15. 2. The optical system according to claim 1, wherein at least one of the first and second transmissive-reflective surfaces is a flat surface.

16. In the wavelength band used, when the element in the second row and second column of the Mueller matrix corresponding to the quarter wave plate is a22 and the element in the third row and second column is a32, -0.25≦a22≦0.25 -0.25≦a32≦0.25 2. The optical system according to claim 1, wherein the following condition is satisfied:

17. 0.10≦zm1 / f≦0.55 2. The optical system according to claim 1, wherein the following condition is satisfied:

18. 18. An imaging device comprising: the optical system according to claim 1; and an imaging element that receives an image formed by the optical system.

Images