Imaging optics, portable communication device and imaging apparatus

Abstract

An imaging optics device with zoom lens functionality is provided, along with a portable communication device and an imaging apparatus, each including such imaging optics. A zoom angle of 1 / 3 inch or larger can be achieved with a relatively small module size. An imaging optical device includes: an optical unit comprising a first lens group and a second lens group arranged sequentially from the object side, wherein the first lens group has an optical positive focal length facing an imaging plane, the second lens group is disposed between the first lens group and the imaging plane and includes at least one focal length-free reflective optical element, the first lens group faces the object, the first lens in the first lens group closest to the object has a convex surface convex towards the object, the reflective optical element disposed in the second lens group includes at least a first reflective optical element and a second reflective optical element, the first reflective optical element being used to perform total internal reflection (TIR) ​​on incident light via a first reflecting surface, and then reflect the light via one or more internal reflecting surfaces to exit the light from the first reflecting surface toward the second reflecting surface, the first reflecting surface being a plane inclined at an angle ranging from 40 to 50 degrees relative to the optical axis of the light incident on the reflective optical element, the field of view (FOV) of the optical unit being in the range of 4 to 40 degrees, and the reflective optical element being relative to the d-line (wavelength 587.6). The refractive index (nm) is in the range of 1.6 to 2.1.

Description

Technical Field

[0001] This invention relates to imaging optics, and to portable communication devices and imaging apparatuses that respectively include such imaging optics. Background Technology

[0002] In recent years, portable communication devices, represented by smartphones, have become increasingly popular, leading to a diversification of the types of imaging lenses required. The size of the imaging lens module affects the size of the product it is integrated into. Therefore, improving the performance specifications of imaging lenses while maintaining a compact module thickness has become an urgent need. Specific improvements in imaging lens performance specifications include increasing the angle of view, enhancing telephoto capabilities, increasing the diameter, and improving optical performance.

[0003] In recent years, multi-camera systems have become widely used as imaging devices in smartphones. Within the smartphone product line, zoom lenses play a crucial role in differentiating products from competitors. For example, users have a need for zoom lenses in various scenarios, such as observing and photographing distant subjects during travel or sporting events, as well as capturing the surrounding environment or celestial bodies. It should be noted that, in the context of this invention, zoom lens refers to a telephoto lens, not a zoom zoom lens.

[0004] Currently, as an imaging optical device for such an imaging lens module with zoom lens function (specifically, for smartphones), a periscope imaging optical unit including a right-angle prism is used to reduce the height of the lens unit (for example, see Patent Document 1).

[0005] [Patent Document 1] Chinese Patent No. 104898353 Summary of the Invention Traditionally, periscope imaging optical units (such as the periscope imaging optical unit disclosed in Patent Document 1) employ right-angle prisms without refractive power. However, this construction corresponds to adding a right-angle prism to a conventional zoom lens optical unit. Therefore, although the module's thickness dimension can be reduced by folding the optical path, the overall length of the zoom lens optical unit will increase accordingly due to the added length of the prism.

[0006] Specifically, when attempting to pair a high-pixel sensor (i.e., a non-small sensor) with a high-magnification zoom lens, the zoom lens optical unit requires an extremely long optical path. As mentioned above, even with a periscope structure to reduce the height of the lens unit, the optical path still needs to maintain a certain length after folding. Therefore, such a lens unit occupies a large volume inside the smartphone, thus hindering the reduction in the size and thickness of the smartphone.

[0007] Therefore, increasing the optical path length of the optical unit is unavoidable in order to improve the specifications of the lens unit suitable for telephoto imaging. Consequently, a linear structure without optical path folding elements would increase the thickness of the smartphone. Conversely, a periscope structure including optical path folding elements would increase the proportion of the lens unit's volume within the smartphone's overall internal volume, leading to not only increased thickness but also a larger overall size – a problem that urgently needs to be addressed.

[0008] The present invention is based on the above-mentioned technical background. The purpose of the present invention is to provide a structure that enables a zoom angle of 1 / 3 inch or larger to be achieved with a smaller module size for imaging optical devices with zoom lens function, and portable communication devices and imaging devices that respectively include such imaging optical devices.

[0009] To address the above problems, the present invention provides the following solution.

[0010] (1) An imaging optical device includes: An optical unit includes a first lens group and a second lens group arranged sequentially from the object side. The first lens group has a positive optical focal length facing the imaging plane, and the second lens group is disposed between the first lens group and the imaging plane and includes at least one focal length-free reflective optical element. The first lens group faces the object, and the first lens in the first lens group, which is positioned closest to the object, has a convex surface that protrudes towards the object. The reflective optical element disposed in the second lens group includes at least a first reflective optical element and a second reflective optical element. The first reflective optical element is used to perform total internal reflection of the incident light through a first reflecting surface by satisfying the total internal reflection (TIR) ​​condition, and then reflect the light through one or more internal reflecting surfaces, so as to emit the light from the first reflecting surface toward the second reflecting surface. The first reflective surface is tilted by a range of 40° relative to the optical axis of the light incident on the reflective optical element. Up to 50 The plane of angles, The field of view (FOV) of the optical unit is 4. Up to 40 Within the range, The refractive index of the reflective optical element relative to the d-line (wavelength of 587.6 nanometers, nm) is in the range of 1.6 to 2.1.

[0011] (2) The imaging optical device according to (1), wherein, in the one or more inner reflecting surfaces, the first inner reflecting surface to which the reflected light reflected by the first reflecting surface of the reflecting optical element can be directly incident is tilted by a range of 21° relative to the optical axis of the light incident on the reflecting optical element. Up to 24 A plane at an angle.

[0012] (3) The imaging optical device according to (1), wherein, in the one or more inner reflecting surfaces, the first inner reflecting surface to which the reflected light reflected by the first reflecting surface of the reflecting optical element can be directly incident is tilted by a range of -21 relative to the optical axis of the light incident on the reflecting optical element. up to –24 A plane at an angle.

[0013] (4) An imaging optical device according to any one of (1) to (3), wherein the ratio of the maximum dimension (in millimeters, mm) from the incident surface of the reflecting optical element to the exit surface of the reflecting optical element to the optical path length (in mm) along the central optical axis from the incident surface of the reflecting optical element to the imaging surface is less than or equal to 45%.

[0014] (5) The imaging optical device according to any one of (1) to (4) further includes a shielding material between the first reflective optical element and the second reflective optical element of the second lens group, wherein the shielding material is used to partially shield the first reflective surface.

[0015] (6) The imaging optical device according to (5), wherein the ratio of the size of the shielding material (in mm) to the effective optical size of the first reflective surface (in mm) is in the range of 20% to 60%.

[0016] (7) An imaging optical device according to any one of (1) to (6), wherein the first lens constituting the first lens group has positive refractive power, and the focal length P1 (in mm) of the first lens and the focal length P2 (in mm) of the first lens group satisfy the following expression (1): 0.25 P1 / P2 0.7 (1).

[0017] (8) An imaging optical device according to any one of (1) to (7), wherein the optical unit is configured to enable the first lens group to move entirely or partially in a direction perpendicular to the optical axis, thereby achieving optical image stabilization.

[0018] (9) The imaging optical device according to any one of claims 1 to 3, wherein the optical unit is used to enable the imaging surface to move in a direction perpendicular to the optical axis, thereby achieving optical image stabilization.

[0019] (10) An imaging optical device according to any one of (1) to (9), wherein the first lens group comprises at least two lens elements, and the optical unit is configured to adjust the focal position by moving one or more lens elements of the first lens group or by moving the first lens group as a whole in the direction of the optical axis.

[0020] (11) An imaging optical device according to any one of (1) to (10), wherein the optical unit is used to adjust the focal position by moving the imaging surface along the optical axis.

[0021] A portable communication device comprising an imaging optics according to any one of (1) to (11).

[0022] An imaging apparatus comprising an imaging optics according to any one of claims (1) to (11).

[0023] The present invention provides a configuration that enables a zoom angle of 1 / 3 inch or larger to be achieved with a smaller module size for an imaging optics device with a zoom lens function, and a portable communication device and an imaging device respectively including such an imaging optics device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the imaging optical device according to the first embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of the imaging optical device according to the second embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the imaging optical device according to the third embodiment of the present invention.

[0027] Figure 4 This is a graph that verifies the results of Example 1 (spherical aberration).

[0028] Figure 5 This is a graph showing the results (image) of Example 1.

[0029] Figure 6 This is a graph that verifies the result (distortion) of Example 1.

[0030] Figure 7 This is a graph that verifies the results of Example 2 (spherical aberration).

[0031] Figure 8 This is a graph showing the results (image) of Example 2.

[0032] Figure 9 This is a graph that verifies the result (distortion) of Example 2.

[0033] Figure 10 This is a graph that verifies the results of Example 3 (spherical aberration).

[0034] Figure 11 This is a graph showing the results (image) of Example 3.

[0035] Figure 12 This is a graph verifying the result (distortion) of Example 3. Detailed Implementation

[0036] In the following detailed description, embodiments of the present invention will be provided with reference to the accompanying drawings. It should be noted that, for clarity and ease of understanding, the drawings used in the following description may show enlarged features. Therefore, the dimensions of the corresponding components may not be consistent with reality. Furthermore, the materials and dimensions exemplified in the following description are merely examples. Therefore, the present invention is not necessarily limited thereto, and appropriate modifications and implementations can be made without altering the beneficial effects of the invention.

[0037] (Imaging optics: First embodiment) Figure 1 This is a schematic diagram of the structure of the imaging optical device according to the first embodiment of the present invention.

[0038] The imaging optical device 1 of this embodiment includes: an optical unit 5, including a first lens group 10 having an optical positive focal length toward the imaging surface im and a second lens group 20 disposed between the first lens group 10 and the imaging surface im and including at least one focal length-free reflective optical element 20A; and an imaging element 6 constituting the imaging surface im.

[0039] The first lens group 10 faces the object Ob, which is the subject, and includes four lenses (i.e., lens elements): a first lens 10A, a second lens 10B, a third lens 10C, and a fourth lens 10D, which are arranged sequentially starting from the object Ob side. Among these lenses, at least the first lens 10A is a lens with a convex surface 10Ar that protrudes towards the object Ob.

[0040] The first lens 10A constituting the first lens group 10 has positive refractive power. The first lens 10A, the second lens 10B, the third lens 10C and the fourth lens 10D are preferably configured such that the focal length P1 (mm) of the first lens 10A and the focal length P2 (mm) of the first lens group 10 satisfy the following expression (1).

[0041] 0.25 P1 / P2 0.7 (1) This first lens group 10 may include at least two lens elements. The optical unit 5 can be used to adjust the focal position of the imaging optics 1 by moving one or more lens elements or moving the first lens group 10 as a whole in the direction of the optical axis.

[0042] The second lens group 20 includes one or more reflective optical elements 20A. In this embodiment, the reflective optical element 20A includes: a first prism 25 (first reflective optical element) disposed behind the first lens group 10 and including the incident surface Q1 of the second lens group 20; and a second prism (second reflective optical element) facing the imaging surface im and including the exit surface Q2 of the second lens group 20.

[0043] The first prism 25 includes at least an incident surface Q1, a first reflecting surface 20A1, and a first internal reflecting surface 21A. The first prism 25 may be made of solid optical glass material, and each plane of the first prism 25 may be treated with directional reflective coating or light-transmitting coating.

[0044] The incident light L1 from the incident surface Q1 of the first prism 25 is first reflected by the first reflecting surface 20A1, then reflected by the first inner reflecting surface 21A towards the first reflecting surface 20A1, and then passes through the first reflecting surface 20A1 and is incident on the second reflecting surface 20A2 of the second prism 26.

[0045] The first reflecting surface 20A1 performs total internal reflection of the incident light L1 entering the first prism 25 through the incident surface Q1 by satisfying the total internal reflection (TIR) ​​condition. It is assumed that the light loss of the first reflecting surface 20A1 is less than 10%.

[0046] The first reflecting surface 20A1 is a plane tilted at an angle θ1 relative to the optical axis of the incident light L1, i.e., within a range of 40°. Up to 50 The angle, specifically 45 degrees in this embodiment. Therefore, the incident light L1 travels at approximately 90 degrees in the direction of the first internal reflecting surface 21A. Angular reflection.

[0047] The first inner reflecting surface 21A causes the reflected light L2, which has been reflected by the first reflecting surface 20A1, to undergo total internal reflection towards the second prism 26, forming reflected light L3. This reflected light L3 can achieve a reflection rate of approximately 90°. The light is incident at an angle to the first reflecting surface 20A1, and then passes through the first reflecting surface 20A1 into the second prism 26.

[0048] The first internal reflecting surface 21A is a plane tilted at an angle θ2 relative to the optical axis of the incident light L1, i.e., within the range of 21... Up to 24 The angle, specifically 22.5 degrees in this embodiment. Therefore, the reflected light L3, after being reflected by the first inner reflecting surface 21A, can travel at approximately 45 degrees. The light is incident at an angle onto the exit surface Q2 of the second prism 26.

[0049] Note that the first inner reflecting surface 21 may not use angle θ2, but rather be tilted relative to the optical axis of the incident light L1 by angle θ3, i.e., in the range of –21. up to –24 The angle is specifically -22.5. .

[0050] The second prism 26 includes at least a second reflecting surface 20A2 facing the first reflecting surface 20A1 of the first prism 25, a second inner reflecting surface 21B, and an exiting surface Q2. The second prism 26 may be made of solid optical glass material, and each plane of the second prism 26 may be treated with directional reflective coating or light-transmitting coating.

[0051] The incident light L3, which exits from the first prism 25 and is incident on the second reflecting surface 20A2 of the second prism 26, is first reflected by the exiting surface Q2, then reflected by the second inner reflecting surface 21B toward the second reflecting surface 20A2, and then reflected by the second reflecting surface 20A2 and passed through the exiting surface Q2 to form an image on the imaging surface im of the imaging element 6.

[0052] The exit surface Q2 is at approximately 90 degrees. Light incident at an angle of approximately 45 degrees is transmitted and transmitted. Light incident at an angle of approximately 45 undergoes total internal reflection. The exit surface Q2, by satisfying the total internal reflection (TIR) ​​condition, exits from the first prism 25, passes through the second reflecting surface 20A2, and travels at approximately 45 degrees. The reflected light L3, incident at an angle to the exit surface Q2, undergoes total internal reflection towards the second inner reflecting surface 21B.

[0053] The second inner reflecting surface 21B reflects the reflected light L4, which has been reflected by the exiting surface Q2, toward the second reflecting surface 20A2. The second inner reflecting surface 21B is tilted at an angle θ3 (e.g., –22.5°) relative to the optical axis of the incident light L1. The plane of the second inner reflecting surface 21B. Therefore, the reflected light L5, after being reflected by the second inner reflecting surface 21B, can move at approximately 45 degrees. The incident light is incident on the second reflecting surface 20A2 of the second prism 26 at an angle. Note that the angle of the second inner reflecting surface 21B of the second prism 26 described above is merely illustrative and not limiting.

[0054] The second reflecting surface 20A2 performs total internal reflection of the reflected light L5 reflected by the second internal reflecting surface 21B by satisfying the total internal reflection (TIR) ​​condition. It is assumed that the optical loss of the second reflecting surface 20A2 is less than 10%.

[0055] The second reflecting surface 20A2 is tilted at an angle θ1 (e.g., 45°) relative to the optical axis of the incident light L1. The plane of the exit surface Q2. Therefore, the reflected light L5 travels at approximately 90 degrees in the direction of the exit surface Q2. The light is reflected at an angle of approximately 90 degrees, forming reflected light L6. Then, reflected light L6 can then be reflected at approximately 90 degrees... The light is incident on the exit surface Q2 at an angle, and then passes through the exit surface Q2 to form an image on the imaging surface im. Note that the angle of the second reflecting surface 20A2 of the second prism 26 described above is merely illustrative and not limiting.

[0056] The imaging element 6 can be a known imaging element such as a CCD sensor or a CMOS sensor. Light entering the first lens group 10 and including the image will be imaged on the imaging surface im, which serves as the light-receiving surface.

[0057] Note that a partially shielding material 22 can be provided between the first reflecting surface 20A1 of the first prism 25 and the second reflecting surface 20A2 of the second prism 26 to partially shield the first reflecting surface 20A1. This shielding material 22 can prevent stray light that would degrade image quality from entering the second prism 26.

[0058] Preferably, the shielding material 22 is formed such that the ratio of the size (mm) of the shielding material 22 to the effective optical size (mm) of the first reflective surface 20A1 is in the range of 20% to 60%.

[0059] Furthermore, it is preferable to form an infrared cutoff filter 27 between the exit surface Q2 of the second prism 26 and the imaging surface im of the imaging element 6. This can reduce the influence of infrared radiation on the image formed on the imaging surface im.

[0060] In the imaging optical device 1 of this embodiment having the above-described structure, the field of view (FOV) of the optical unit 5 is 4 Up to 40 Within the range.

[0061] The first prism 25 and the second prism 26 constituting the reflective optical element 20A are both made of a material with a refractive index in the range of 1.6 to 2.1 relative to the d-line (wavelength of 587.6 nm).

[0062] The ratio of the maximum dimension (mm) from the incident surface Q1 of the first prism 25 in the reflecting optical element 20A constituting the second lens group 20 to the exit surface Q2 of the second prism 26 to the optical path length (mm) along the central optical axis from the incident surface Q1 of the first prism 25 in the reflecting optical element 20A to the imaging surface im of the imaging element 6 is preferably less than or equal to 45%.

[0063] Optical image stabilization can be achieved when the support member (not shown) supporting the entire first lens group 10 is movable in a direction perpendicular to the optical axis of the first lens group 10. For example, image stabilization can be added by employing a device that allows the first lens group 10 to vibrate in a direction perpendicular to the optical axis.

[0064] Furthermore, optical image stabilization can be achieved when the support member (not shown) supporting the imaging element 6 is movable in a direction perpendicular to the optical axis of the reflected light L6 incident on the imaging surface im. For example, image stabilization can be added by employing a device that allows the imaging element 6 to jitter in a direction perpendicular to the optical axis.

[0065] According to the imaging optical device 1 of this embodiment with the above-described structure, a zoom angle of 1 / 3 inch or larger can be achieved with a smaller module size, the zoom angle corresponding to a range of 4 for the optical unit 5. Up to 40 The field of view (FOV).

[0066] (Imaging Optics: Second Embodiment) Figure 2 This is a schematic diagram of the structure of the imaging optical device according to the second embodiment of the present invention.

[0067] Components similar to those in the first embodiment are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0068] The imaging optical device 2 in this embodiment includes a first lens group 10 and a focal length-free second lens group 30, which together constitute an optical unit 8.

[0069] The second lens group 30 includes two triangular prisms: a first prism 35 (a first reflecting optical element) and a second prism 36 (a second reflecting optical element), which together constitute the reflecting optical element 30A.

[0070] In this embodiment, the first prism 35 with a triangular cross-section includes at least an incident surface Q31, a first reflecting surface 30A1, and a first internal reflecting surface 31A. This first prism 35 can be made of solid optical glass material, and each plane of the first prism 35 can be treated with directional reflective coating or light-transmitting coating.

[0071] The incident light L31 from the incident surface Q31 of the first prism 35 is first reflected by the first reflecting surface 30A1, then reflected by the first inner reflecting surface 31A towards the incident surface Q31, then reflected by the incident surface Q31 towards the first reflecting surface 30A1, then passes through the first reflecting surface 30A1, and is incident on the second reflecting surface 30A2 of the second prism 36.

[0072] The first reflecting surface 30A1, by satisfying the TIR condition, performs total internal reflection on the incident light L31 entering the first prism 35 via the incident surface Q31. This first reflecting surface 20A1 is a plane tilted at an angle θ1 relative to the optical axis of the incident light L31, i.e., within a range of 40°. Up to 50 The angle, specifically 45 degrees in this embodiment. Therefore, the incident light L31 travels at approximately 90 degrees in the direction of the first internal reflecting surface 31A. Angular reflection.

[0073] The second prism 36, which has a triangular cross-section, includes at least a second reflecting surface 30A2 facing the first reflecting surface 30A1 of the first prism 35, a second inner reflecting surface 31B, and an exiting surface Q32. This second prism 26 can be made of solid optical glass material, and each plane of the second prism 26 can be treated with directional reflective coating or light-transmitting coating.

[0074] The incident light L34, which exits from the first prism 35 and is incident on the second reflecting surface 30A2 of the second prism 36, is first reflected by the exiting surface Q32, then reflected by the second inner reflecting surface 31B toward the second reflecting surface 30A2, then reflected by the second reflecting surface 30A2 toward the exiting surface Q32, and then passes through the exiting surface Q32 to form an image on the imaging surface im of the imaging element 6.

[0075] Furthermore, a shielding material 32 that partially blocks the first reflecting surface 30A1 of the first prism 35 can be provided between the first prism 35 and the second prism 36. This shielding material 32 can prevent stray light that would degrade image quality from entering the second prism 36.

[0076] According to the imaging optical device 2 of this embodiment with the above-described structure, the incident light L31 corresponding to the transmitted light including the image of the object Ob as the subject first passes through the first lens group 10, then enters the first prism 35 constituting the second lens group 30 via the incident surface Q31, and then passes through the first reflecting surface 30A1 toward the first inner reflecting surface 31A at approximately 90 degrees. Angular reflection.

[0077] The reflected light L32, after total internal reflection by the first reflecting surface 30A1, will be reflected by the first inner reflecting surface 31A. The first inner reflecting surface 31A is tilted at an angle θ2 relative to the optical axis of the incident light L31, which is in the range of 21°. Up to 24 The angle, specifically 22.5 degrees in this embodiment. Then, the reflected light L33, after being reflected by the first inner reflecting surface 31A, can move at approximately 45 degrees. The light is incident at an angle to the incident surface Q31 and undergoes total internal reflection to form reflected light L34.

[0078] Incident surface Q31 at approximately 90 Light incident at an angle of approximately 45 degrees is transmitted and transmitted. The light incident at an angle of approximately 45 degrees undergoes total internal reflection. The reflected light L34, after being reflected by the incident surface Q31, can be incident perpendicularly to the first reflecting surface 30A1 and pass through it, subsequently traveling at approximately 45 degrees... The light is incident at an angle onto the exit surface Q32 of the second prism 26.

[0079] The Q32 exit surface is at approximately 90 degrees. Light incident at an angle of approximately 45 degrees is transmitted and transmitted. The incident light at the angle undergoes total internal reflection. The exit surface Q32 conducts total internal reflection of the reflected light L34 entering the second prism 36 towards the second inner reflecting surface 31B.

[0080] The second inner reflecting surface 31B reflects the reflected light L35 from the exiting surface Q32 towards the second reflecting surface 30A2. This second inner reflecting surface 31B is tilted relative to the optical axis of the incident light L31 at an angle θ3 (e.g., –22.5°). The plane of the second inner reflecting surface 31B. Therefore, the reflected light L36, reflected by the second inner reflecting surface 31B, can move at approximately 45 degrees. The incident light is incident on the second reflecting surface 20A2 of the second prism 26 at an angle. Note that the angle of the second inner reflecting surface 31B of the second prism 36 described above is merely illustrative and not limiting.

[0081] The reflected light L36 incident on the second reflecting surface 30A2 undergoes total internal reflection by satisfying the TIR condition, and moves at approximately 90 degrees in the direction of the exit surface Q32. The light is reflected at an angle of approximately 90 degrees, forming reflected light L37. Then, reflected light L37 can then be reflected at approximately 90 degrees... The incident light is incident at an angle to the exit surface Q2, and then passes through the exit surface Q2 to form an image on the imaging surface im.

[0082] In the imaging optical device 2 of this embodiment with the above-described structure, the field of view (FOV) of the optical unit 8 is also 4. Up to 40 Within the range.

[0083] The first prism 35 and the second prism 36 constituting the reflective optical element 30A are both made of a material with a refractive index in the range of 1.6 to 2.1 relative to the d-line (wavelength of 587.6 nm).

[0084] The ratio of the maximum dimension (mm) from the incident surface Q31 of the first prism 35 in the reflecting optical element 30A constituting the second lens group 30 to the exit surface Q32 of the second prism 36 to the optical path length (mm) along the central optical axis from the incident surface Q31 of the first prism 35 in the reflecting optical element 30A to the imaging surface im of the imaging element 6 is preferably less than or equal to 45%.

[0085] (Imaging Optics: Third Embodiment) Figure 3 This is a schematic diagram of the structure of the imaging optical device according to the third embodiment of the present invention.

[0086] Components similar to those in the first embodiment are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0087] The imaging optical device 3 in this embodiment includes a first lens group 40 and a focal length-free second lens group 50, which together constitute an optical unit 9.

[0088] The imaging optics 3 in this embodiment shows a layout example: the incident side of the light including the image of object Ob is approximately perpendicular (90°) to the imaging plane im of the imaging element 6. ).

[0089] The first lens group 40 faces the object Ob, which is the subject, and includes two lenses (i.e., lens elements), namely a first lens 40A and a second lens 40B, which are arranged sequentially starting from the object Ob side. Among these lenses, at least the first lens 40A is a lens with a convex surface 40Ar that protrudes towards the object Ob.

[0090] The first lens 40A constituting the first lens group 40 has positive refractive power. The first lens 40A and the second lens 40B are preferably configured such that the focal length P1 (mm) of the first lens 40A and the focal length P2 (mm) of the first lens group 40 satisfy the following expression (1).

[0091] 0.25 P1 / P2 0.7 (1) This first lens group 40 may include at least two lens elements. The optical unit 9 can be used to adjust the focal position of the imaging optics 3 by moving one or more lens elements or moving the first lens group 40 as a whole in the direction of the optical axis.

[0092] The second lens group 50 includes a reflective optical element 50A. In this embodiment, the reflective optical element 50A includes two triangular prisms, namely a first prism 55 and a second prism 56.

[0093] The first prism 55 includes at least an incident surface Q51, a first reflecting surface 50A1, and a first internal reflecting surface 51A. The first prism 55 may be made of solid optical glass material, and each plane of the first prism 55 may be treated with directional reflective coating or light-transmitting coating.

[0094] The first reflecting surface 50A1 performs total internal reflection of the incident light L41 entering the first prism 55 via the incident surface Q51 by satisfying the TIR condition. The first reflecting surface 50A1 is a plane tilted at an angle θ1 relative to the optical axis of the incident light L41, i.e., within a range of 40°. Up to 50 The angle, specifically 45 degrees in this embodiment. Therefore, the incident light L41 travels at approximately 90 degrees in the direction of the first internal reflecting surface 51A. Angular reflection.

[0095] The first inner reflecting surface 51A causes the reflected light L42, which has been reflected by the first reflecting surface 50A1, to undergo total internal reflection towards the incident surface Q51. The first inner reflecting surface 51A is a plane tilted at an angle θ2 relative to the optical axis of the incident light L41, i.e., within a range of 21°. Up to 24 The angle, specifically 22.5 degrees in this embodiment. .

[0096] Incident surface Q51 at approximately 90 Light incident at an angle of approximately 45 degrees is transmitted and transmitted. Light incident at an angle of approximately 45 degrees undergoes total internal reflection. Therefore, the reflected light L43, after being reflected by the first inner reflecting surface 51A, is reflected again by the incident surface Q51 and can then be incident perpendicularly on the first reflecting surface 50A1, forming reflected light L44. This reflected light then passes through the reflecting surface and can still travel at approximately 45 degrees... The light is incident at an angle onto the exit surface Q52 of the second prism 56.

[0097] The exit surface Q52 of the second prism 56 is at approximately 90 degrees. Light incident at an angle of approximately 45 degrees is transmitted and transmitted. The light incident at the angle undergoes total internal reflection. Therefore, the reflected light L44 from the first prism 55 is reflected by the exit surface Q52 and can then be incident on the second inner reflecting surface 51B to form the reflected light L45.

[0098] The second inner reflecting surface 51B reflects the reflected light L45, which is reflected by the exiting surface Q52, toward the second reflecting surface 50A2.

[0099] The second reflecting surface 50A2, by satisfying the TIR condition, performs total internal reflection of the reflected light L46 reflected by the second inner reflecting surface 51B. The second reflecting surface 50A2 is a plane tilted at an angle θ1 relative to the optical axis of the incident light L41, i.e., within a range of 40°. Up to 50 The angle, specifically 45 degrees in this embodiment. Therefore, the reflected light L46 travels at approximately 90 degrees in the direction of the exit surface Q52. The light is reflected at an angle of approximately 90 degrees, forming reflected light L47. Then, reflected light L47 can then be reflected at approximately 90 degrees... The light is incident at an angle to the exit surface Q52, and then passes through the exit surface Q5 to form an image on the imaging surface im that constitutes the imaging element 6. Note that the angle of the second inner reflecting surface 50A2 of the second prism 56 described above is illustrative only and not limiting.

[0100] Note that a partially shielding material 52 can be provided between the first reflecting surface 50A1 of the first prism 55 and the second reflecting surface 50A2 of the second prism 56 to partially shield the first reflecting surface 50A1. This shielding material 52 can prevent stray light that reduces image quality from entering the second prism 56.

[0101] Preferably, the shielding material 52 is formed such that the ratio of the size (mm) of the shielding material 52 to the effective optical size (mm) of the first reflective surface 50A1 is in the range of 20% to 60%.

[0102] Furthermore, it is preferable to form an infrared cutoff filter 27 between the exit surface Q52 of the second prism 56 and the imaging surface im of the imaging element 6. This can reduce the influence of infrared radiation on the image formed on the imaging surface im.

[0103] In the imaging optical device 3 of this embodiment having the above-described structure, the field of view (FOV) of the optical unit 9 is 4 Up to 40 Within the range.

[0104] The first prism 55 and the second prism 56 constituting the reflective optical element 50A are both made of a material with a refractive index in the range of 1.6 to 2.1 relative to the d-line (wavelength of 587.6 nm).

[0105] The ratio of the maximum dimension (mm) from the incident surface Q51 of the first prism 55 in the reflective optical element 50A constituting the second lens group 50 to the exit surface Q52 of the second prism 56 to the optical path length (mm) along the central optical axis from the incident surface Q51 of the first prism 55 in the reflective optical element 50A to the imaging surface im of the imaging element 6 is preferably less than or equal to 45%.

[0106] According to the imaging optical device 3 of this embodiment with the above-described structure, a zoom angle of 1 / 3 inch or larger can be achieved with a smaller module size, the zoom angle corresponding to a range of 4 for the optical unit 5. Up to 40 The field of view (FOV). Furthermore, according to this embodiment, the principal plane of the first lens 40A constituting the first lens group 40 and the imaging plane im of the imaging element 6 can be set at a right angle.

[0107] (Portable communication devices) For example, using the aforementioned imaging optics as built-in cameras in portable communication devices such as smartphones can enable smartphones with wide-angle, high-magnification zoom lenses without increasing the thickness of the smartphone.

[0108] (Imaging device) For example, by using the above-mentioned imaging optical devices as imaging optical units in imaging devices such as digital cameras, a slim and portable digital camera with a wide-angle and high-magnification zoom lens can be realized.

[0109] While embodiments of the present invention have been described above, these embodiments are merely exemplary and not intended to limit the scope of the invention. Such embodiments may be implemented in various other ways and may be partially omitted, substituted, or modified in various manner within the spirit of the invention. Such embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the claimed invention and its equivalents.

[0110] Example The beneficial effects of the above embodiments have been verified.

[0111] (Verification Example 1) According to Figure 1 The spherical aberration (%) of the optical unit of the imaging optics of the first embodiment shown was measured at each wavelength. Figure 4 The results are shown. Additionally, the astigmatism (%) of the imaging optics of the first embodiment was measured. Figure 5 The results are shown. Furthermore, the distortion (%) of the imaging optics of the first embodiment was measured. Figure 6 The results are shown.

[0112] Figures 4 to 6 The measurement results shown confirm that the construction using the first embodiment can adequately correct each of the aberrations, astigmatism, and distortion.

[0113] (Verification Example 2) According to Figure 2The spherical aberration (%) of the optical unit of the imaging optics device in the second embodiment shown was measured at each wavelength. Figure 7 The results are shown. Additionally, the astigmatism (%) of the imaging optics of the second embodiment was measured. Figure 8 The results are shown. Furthermore, the distortion (%) of the imaging optics in the second embodiment was measured. Figure 9 The results are shown.

[0114] Figures 7 to 9 The measurement results shown confirm that the construction using the second embodiment can also adequately correct each of the aberrations, astigmatism, and distortion.

[0115] (Verification Example 3) According to Figure 3 The spherical aberration (%) of the optical unit of the imaging optics device in the third embodiment shown was measured at each wavelength. Figure 10 The results are shown. Additionally, the astigmatism (%) of the imaging optics of the first embodiment was measured. Figure 11 The results are shown. Furthermore, the distortion (%) of the imaging optics of the first embodiment was measured. Figure 12 The results are shown.

[0116] Figures 10 to 12 The measurement results shown confirm that the construction using the third embodiment can also adequately correct each of the aberrations, astigmatism, and distortion.

Claims

1. An imaging optical device, characterized in that, include: An optical unit includes a first lens group and a second lens group arranged sequentially from the object side. The first lens group has a positive optical focal length facing the imaging plane, and the second lens group is disposed between the first lens group and the imaging plane and includes at least one focal length-free reflective optical element. The first lens group faces the object, and the first lens in the first lens group, which is positioned closest to the object, has a convex surface that protrudes towards the object. The reflective optical element disposed in the second lens group includes at least a first reflective optical element and a second reflective optical element. The first reflective optical element is used to perform total internal reflection (TIR) ​​on the incident light via a first reflecting surface, and then reflect the light via one or more internal reflecting surfaces, so as to emit the light from the first reflecting surface toward the second reflecting surface. The first reflective surface is tilted by a range of 40° relative to the optical axis of the light incident on the reflective optical element. Up to 50 A plane of angles, The field of view (FOV) of the optical unit is 4. Up to 40 Within the range, The refractive index of the reflective optical element relative to the d-line (wavelength of 587.6 nanometers, nm) is in the range of 1.6 to 2.

1.

2. The imaging optical device according to claim 1, characterized in that, In the one or more inner reflecting surfaces, the first inner reflecting surface to which the reflected light from the first reflecting surface of the reflecting optical element can directly incident is tilted by a range of 21° relative to the optical axis of the light incident on the reflecting optical element. Up to 24 A plane at an angle.

3. The imaging optical device according to claim 1, characterized in that, In the one or more inner reflecting surfaces, the first inner reflecting surface to which the reflected light from the first reflecting surface of the reflecting optical element can directly incident is tilted by a range of -21° relative to the optical axis of the light incident on the reflecting optical element. up to –24 A plane at an angle.

4. The imaging optical device according to any one of claims 1 to 3, characterized in that, The ratio of the maximum dimension (in millimeters, mm) from the incident surface to the exit surface of the reflective optical element to the optical path length (in mm) along the central optical axis from the incident surface to the imaging surface of the reflective optical element is less than or equal to 45%.

5. The imaging optical device according to any one of claims 1 to 3, characterized in that, It also includes a shielding material between the first reflective optical element and the second reflective optical element of the second lens group, wherein the shielding material is used to partially shield the first reflective surface.

6. The imaging optical device according to claim 5, characterized in that, The ratio of the size of the shielding material (in mm) to the effective optical size (in mm) of the first reflective surface is in the range of 20% to 60%.

7. The imaging optical device according to any one of claims 1 to 3, characterized in that, The first lens constituting the first lens group has positive refractive power. The focal length P1 (in mm) of the first lens and the focal length P2 (in mm) of the first lens group satisfy the following expression (1): 0.25 P1 / P2 0.7 (1).

8. The imaging optical device according to any one of claims 1 to 3, characterized in that, The optical unit is used to enable the first lens group to move entirely or partially in a direction perpendicular to the optical axis, thereby achieving optical image stabilization.

9. The imaging optical device according to any one of claims 1 to 3, characterized in that, The optical unit is used to enable the imaging surface to move in a direction perpendicular to the optical axis, thereby achieving optical image stabilization.

10. The imaging optical device according to any one of claims 1 to 3, characterized in that, The first lens group includes two or more lens elements. The optical unit is used to adjust the focal position by moving one or more lens elements of the first lens group or by moving the first lens group as a whole in the direction of the optical axis.

11. The imaging optical device according to any one of claims 1 to 3, characterized in that, The optical unit is used to adjust the focal position by moving the imaging surface along the optical axis.

12. A portable communication device, characterized in that, Including the imaging optics according to any one of claims 1 to 3.

13. An imaging device, characterized in that, Including the imaging optics according to any one of claims 1 to 3.

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