3D imaging lens

Abstract

A 3D imaging lens sequentially comprises a first lens, a second lens, a third lens and a polarization element along an optical axis. The first lens has a negative diopter. The second lens has positive diopter. The third lens has positive diopter. The polarizing element includes a plurality of optical units. Each optical unit comprises a first polarization structure, a second polarization structure and a third polarization structure. When light penetrates through the first polarization structure, first linearly polarized light is generated; when the light penetrates through the second polarization structure, second linearly polarized light is generated; when light penetrates through the third polarization structure, third linearly polarized light is generated. The first linearly polarized light, the second linearly polarized light and the third linearly polarized light are not parallel to each other.

Description

Technical Field

[0001] This invention relates to a 3D imaging lens. Background Technology

[0002] An endoscope is an important optical imaging device used in medical diagnosis and surgical assistance. It can penetrate deep into the internal cavities and tissues of the human body for observation, and is therefore widely used in the fields of digestive tract, urinary system, respiratory system, and even minimally invasive surgery. Images obtained through an endoscope allow physicians to detect and diagnose lesions and navigate surgical procedures.

[0003] Most endoscopes currently used in clinical practice are two-dimensional imaging systems, capable of displaying only planar images. This limitation prevents physicians from directly obtaining three-dimensional spatial information from the image data, making it difficult to accurately determine the three-dimensional shape and spatial location of tissues or tumors. This can lead to incomplete identification and increase the risk of accidentally damaging important nerves, blood vessels, and other critical tissues during invasive surgery. Furthermore, the limited two-dimensional information also hinders the positioning calculations of navigation systems, limiting procedures requiring high precision.

[0004] Therefore, with the increasing demand for clinical safety and accuracy, developing an endoscope capable of capturing stereoscopic images to provide depth information and 3D image reconstruction has become an important direction for the development of medical imaging technology. By providing reconstruction of tissue structure and tumor three-dimensional shape, and providing real-time three-dimensional positioning and navigation during surgery, it will help improve diagnostic accuracy and reduce surgical risks, thereby improving the quality of medical care. Summary of the Invention

[0005] This invention provides a 3D imaging lens with high imaging quality.

[0006] According to an embodiment of the present invention, a 3D imaging lens is provided, comprising, sequentially from the object side to the image side along the optical axis, a first lens, a second lens, a third lens, and a polarizing element. The first lens has a negative refractive power. The second lens has a positive refractive power. The third lens has a positive refractive power. The polarizing element comprises a plurality of optical units arranged in an array. Each optical unit includes a first polarization structure, a second polarization structure, and a third polarization structure. When light passes through the first polarization structure, first linearly polarized light is generated; when light passes through the second polarization structure, second linearly polarized light is generated; when light passes through the third polarization structure, third linearly polarized light is generated. The first, second, and third linearly polarized lights are not parallel to each other.

[0007] Based on the above, the 3D imaging lens provided in this embodiment of the invention can perform macro stereoscopic photography in a limited space, and the imaging quality is high.

[0008] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0009] Figure 1 A schematic diagram of a polarization element according to some embodiments of the present invention is shown;

[0010] Figure 2 A schematic diagram of a 3D imaging lens according to a first embodiment of the present invention is shown;

[0011] Figure 3 The modulation transfer function (MTF) curve of the 3D imaging lens according to the first embodiment of the present invention is shown;

[0012] Figure 4A and Figure 4B The field curvature aberrations of the 3D imaging lens according to the first embodiment of the present invention are shown in the meridional direction and the sagittal direction, respectively. Figure 4C The distortion aberrations of a 3D imaging lens according to a first embodiment of the present invention are shown.

[0013] Figure 5 The lateral chromatic aberration and Airy disk of a 3D imaging lens according to a first embodiment of the present invention are shown.

[0014] Figure 6 The distribution of the incident angle of the 3D imaging lens on the imaging plane according to the first embodiment of the present invention is shown;

[0015] Figure 7 The relative illumination distribution of the 3D imaging lens on the imaging plane according to the first embodiment of the present invention is shown;

[0016] Figure 8 A schematic diagram of a 3D imaging lens according to a second embodiment of the present invention is shown;

[0017] Figure 9 The modulation transfer function (MTF) curve of the 3D imaging lens according to the second embodiment of the present invention is shown;

[0018] Figure 10A and Figure 10B The field curvature aberrations of the 3D imaging lens according to the second embodiment of the present invention are shown in the meridional direction and the sagittal direction, respectively. Figure 10C The distortion aberration of a 3D imaging lens according to a second embodiment of the present invention is shown.

[0019] Figure 11 The lateral chromatic aberration and Airy disk of a 3D imaging lens according to a second embodiment of the present invention are shown.

[0020] Figure 12The distribution of the incident angle of the 3D imaging lens on the imaging plane according to the second embodiment of the present invention is shown;

[0021] Figure 13 The relative illumination distribution of the 3D imaging lens on the imaging plane according to the second embodiment of the present invention is shown;

[0022] Figure 14 A schematic diagram of a 3D imaging lens according to a third embodiment of the present invention is shown;

[0023] Figure 15 The modulation transfer function (MTF) curve of the 3D imaging lens according to the third embodiment of the present invention is shown;

[0024] Figure 16A and Figure 16B The field curvature aberrations of the 3D imaging lens according to the third embodiment of the present invention are shown in the meridional direction and the sagittal direction, respectively. Figure 16C The distortion aberration of a 3D imaging lens according to a third embodiment of the present invention is shown;

[0025] Figure 17 The lateral chromatic aberration and Airy disk of a 3D imaging lens according to a third embodiment of the present invention are shown.

[0026] Figure 18 The distribution of the incident angle of the 3D imaging lens on the imaging plane according to the third embodiment of the present invention is shown;

[0027] Figure 19 The relative illumination distribution of the 3D imaging lens on the imaging plane according to the third embodiment of the present invention is shown.

[0028] Symbol explanation:

[0029] 10, 20, 30: 3D imaging lenses

[0030] 110, 210, 310: First lens

[0031] 111, 121, 141, 151, 211, 221, 241, 311, 321, 341: Side view of the object

[0032] 112, 122, 142, 152, 212, 222, 242, 312, 322, 342: side view

[0033] 120, 220, 320: Second lens

[0034] 130, 230, 330: Aperture

[0035] 140, 240, 340: Third lens

[0036] 150: Polarizing element

[0037] 151P: First polarization structure

[0038] 152P: Second polarization structure

[0039] 153P: Third polarization structure

[0040] 154F: Filter unit

[0041] 150U: Optical Unit

[0042] 160, 260, 360: Imaging plane

[0043] A1: Object side

[0044] A2: Image side

[0045] I: optical axis Detailed Implementation

[0046] Reference Figure 1 as well as Figure 2 ,in Figure 1 A schematic diagram of a polarization element according to some embodiments of the present invention is shown. Figure 2 A schematic diagram of a 3D imaging lens according to a first embodiment of the present invention is shown.

[0047] The 3D imaging lens 10 of the first embodiment of the present invention includes, in sequence along the optical axis I from the object side A1 to the image side A2, a first lens 110, a second lens 120, an aperture 130, a third lens 140, and a polarizing element 150. When light emitted from an object to be photographed enters the 3D imaging lens 10 and passes through the first lens 110, the second lens 120, the aperture 130, the third lens 140, and the polarizing element 150 in sequence, an image is formed on the imaging surface 160.

[0048] In this embodiment, the first lens 110, the second lens 120, the third lens 140 and the polarizing element 150 of the 3D imaging lens 10 each have an object side surface 111, 121, 141, 151 facing the object side A1 and allowing imaging light to pass through, and an image side surface 112, 122, 142, 152 facing the image side A2 and allowing imaging light to pass through.

[0049] The first lens 110 has negative refractive power. The optical axis region of the object-side surface 111 of the first lens 110 is concave, and its circumferential region is also concave. The optical axis region of the image-side surface 112 of the first lens 110 is concave, and its circumferential region is also concave. In this embodiment, both the object-side surface 111 and the image-side surface 112 of the first lens 110 are aspherical.

[0050] The second lens 120 has positive refractive power. The optical axis region of the object-side surface 121 of the second lens 120 is convex, and its circumferential region is also convex. The optical axis region of the image-side surface 122 of the second lens 120 is convex, and its circumferential region is concave. In this embodiment, both the object-side surface 121 and the image-side surface 122 of the second lens 120 are aspherical.

[0051] The third lens 140 has positive refractive power. The optical axis region of the object-side surface 141 of the third lens 140 is convex, and its circumferential region is also convex. The optical axis region of the image-side surface 142 of the third lens 140 is convex, and its circumferential region is concave. In this embodiment, both the object-side surface 141 and the image-side surface 142 of the third lens 140 are aspherical.

[0052] The polarization element 150 includes a plurality of optical units 150U arranged in an array. Each optical unit 150U includes a first polarization structure 151P, a second polarization structure 152P, and a third polarization structure 153P. When light passes through the first polarization structure 151P, first linearly polarized light is generated; when light passes through the second polarization structure 152P, second linearly polarized light is generated; and when light passes through the third polarization structure 153P, third linearly polarized light is generated. The first, second, and third linearly polarized lights are not parallel to each other. The first, second, and third polarization structures 151P, 152P, and 153P may be constructed, for example, by a metal wire grid, allowing only polarization components perpendicular to the direction of the metal wire grid to pass through, but are not limited thereto. Furthermore, a three-dimensional image can be obtained by using the obtained first, second, and third linearly polarized lights and by using Stokes vectors and the Frankot-Chellappa integral algorithm. In some preferred embodiments, the angle between any two of the first, second, and third linearly polarized light is 60 degrees. For example, the polarization direction of the first linearly polarized light is 60 degrees from a reference direction, the polarization direction of the second linearly polarized light is 120 degrees from the reference direction, and the polarization direction of the third linearly polarized light is 180 degrees from the reference direction, but this is not a limitation.

[0053] In some embodiments, the object distance of the 3D imaging lens 10 is greater than or equal to 10 mm, and it can be implemented as an endoscope or part of an endoscope. Each optical unit 150U of the polarization element 150 may also include a filter unit 154F, the operating wavelength of which covers the range of 470 nm to 650 nm, enabling the 3D imaging lens 10 to perform macro photography; or, the operating wavelength of the filter unit 154F may cover the range of 930 nm to 950 nm, enabling the 3D imaging lens 10 to improve the diagnostic accuracy of the endoscope and reduce surgical risks through positioning calculations of the navigation system.

[0054] Other detailed optical data for the first embodiment are shown in Table 1. The effective focal length (EFL) of the 3D imaging lens 10 in the first embodiment is 0.574 mm, the field of view (FOV) is 130°, the total track length (TTL) is 3.805 mm, the back focal length (BFL) is 0.212 mm, and the aperture (F-number) is 2.346. The image height is 1.302 mm, slightly larger than the diagonal length of the imaging plane 160° (1.23 mm) to avoid vignetting caused by packaging offset. The entrance pupil diameter is 0.245 mm, and the numerical aperture (NA) is 0.204.

[0055] Table 1:

[0056]

[0057] In Table 1, the spacing represents the distance between the corresponding surface and the next surface on the optical axis I. For example, the spacing of the object-side surface 111 (0.197 mm as shown in Table 1) is the distance between the object-side surface 111 and the image-side surface 112 of the first lens 110 on the optical axis I, which is also the thickness of the first lens 110 on the optical axis I. The spacing of the image-side surface 112 (1.027 mm as shown in Table 1) is the distance between the image-side surface 112 of the first lens 110 and the object-side surface 121 of the second lens 120 on the optical axis I, which is also the thickness of the air gap between the first lens 110 and the second lens 120 on the optical axis I, and so on.

[0058] As shown in Table 1, the 3D imaging lens 10 satisfies the condition 2.0≥f1+f2+f3≥1.0, where f1 is the focal length of the first lens 110, f2 is the focal length of the second lens 120, and f3 is the focal length of the third lens 140.

[0059] As shown in Table 1, the 3D imaging lens 10 satisfies the condition -2.0≤1 / R1-1 / R2≤-1.0, where R1 is the radius of curvature of the object side 111 of the first lens 110 and R2 is the radius of curvature of the image side 112 of the first lens 110.

[0060] As shown in Table 1, the 3D imaging lens 10 satisfies the condition 1.5≥1 / R3-1 / R4≥0.5, where R3 is the radius of curvature of the object side 121 of the second lens 120 and R4 is the radius of curvature of the image side 122 of the second lens 120.

[0061] As shown in Table 1, the 3D imaging lens 10 satisfies the condition 1.9≥1 / R5-1 / R6≥0.9, where R5 is the radius of curvature of the object side 141 of the third lens 140 and R6 is the radius of curvature of the image side 142 of the third lens 140.

[0062] As shown in Table 1, the 3D imaging lens 10 satisfies the condition n2>n1=n3, where n1 is the refractive index of the first lens 110, n2 is the refractive index of the second lens 120, and n3 is the refractive index of the third lens 140.

[0063] As shown in Table 1, the 3D imaging lens 10 satisfies the condition 0.5>D1 / n1+D2 / n2+D3 / n3>0.2, where D1 is the diopter of the first lens 110, D2 is the diopter of the second lens 120, and D3 is the diopter of the third lens 140.

[0064] As shown in Table 1, the 3D imaging lens 10 satisfies the condition υ1=υ3>υ2, where υ1 is the Abbe number of the first lens 110, υ2 is the Abbe number of the second lens 120, and υ3 is the Abbe number of the third lens 140.

[0065] As shown in Table 1, the 3D imaging lens 10 satisfies the condition 0.005>D1 / ν1+D2 / ν2+D3 / ν3>0.002.

[0066] The 3D imaging lens 10 also satisfies the conditional TTL / SDL≥2.5 mm and the conditional TTL<3.9 mm, where TTL is the total length of the 3D imaging lens 10 and SDL is the diagonal length of the imaging plane 160 of the 3D imaging lens 10.

[0067] Furthermore, in this embodiment, the object-side surfaces 111, 121, 141 and the image-side surfaces 112, 122, 142 of the first lens 110, the second lens 120, and the third lens 140 are all aspherical surfaces, and these aspherical surfaces are defined according to the following formula:

[0068] ...(1)

[0069] Y: The distance between a point on the aspherical curve and the optical axis I;

[0070] Z: Aspherical depth, which is the perpendicular distance between a point on the aspherical surface that is Y away from the optical axis I and a tangent plane that is tangent to the vertex on the optical axis I of the aspherical surface.

[0071] R: Radius of curvature of the lens surface;

[0072] K: Conic coefficient;

[0073] a 2i : The second-order aspherical coefficient.

[0074] The aspherical coefficients of the object-side surface 111 of the first lens 110 to the image-side surface 142 of the third lens 140 in formula (1) are shown in Table 2. In Table 2, column number 111 indicates that it is the aspherical coefficient of the object-side surface 111 of the first lens 110, and the other columns are deduced accordingly. The first lens 110, the second lens 120 and the third lens 140 are all even-order aspherical lenses.

[0075] Table 2:

[0076]

[0077] refer to Figure 3 It shows the modulation transfer function (MTF) curve of the 3D imaging lens according to the first embodiment of the present invention to evaluate the resolution and sharpness of the 3D imaging lens 10. Figure 3 In the diagram, curve 0.0F_T represents the tangential direction of the central field of view (0° field of view angle), curve 0.0F_S represents the sagittal direction of the central field of view, curve 1.0F_T represents the tangential direction of the maximum field of view (130° field of view angle), curve 1.0F_S represents the sagittal direction of the maximum field of view, curve 0.5F_T represents the tangential direction of the half field of view (65° field of view angle), and curve 0.5F_S represents the sagittal direction of the half field of view. For example... Figure 3 As shown, for spatial frequencies greater than or equal to 125 lp / mm, the entire field of view exhibits a contrast ratio greater than 0.3. The 3D imaging lens 10 demonstrates excellent resolution and sharpness.

[0078] See also Figures 4A to 4C , Figure 4A and Figure 4B The field curvature aberrations of the 3D imaging lens 10 in the meridional direction and the sagittal direction are shown for wavelengths of 470 nm, 550 nm, 650 nm and 940 nm, respectively. Figure 4C This shows the distortion aberration of the 3D imaging lens 10 at wavelengths of 470 nm, 550 nm, 650 nm, and 940 nm. For example... Figure 4A and Figure 4B As shown, the field curvature aberrations of the four representative wavelengths fall within ±0.05 mm across the entire field of view, indicating that the 3D imaging lens 10 can effectively eliminate aberrations. Figure 4C The maximum distortion rate of the 3D imaging lens 10 is 49.467%, indicating that the 3D imaging lens 10 can provide good imaging quality.

[0079] Figure 5 The diagram illustrates the lateral chromatic aberration and Airy disk of a 3D imaging lens according to a first embodiment of the present invention. Figure 5 As shown, the maximum lateral chromatic aberration of the 3D imaging lens 10 is approximately 1.441 µm, indicating good chromatic aberration control.

[0080] Figure 6 The diagram illustrates the incident angle distribution of the 3D imaging lens on the imaging surface 160 according to a first embodiment of the present invention, where the horizontal axis represents the distance of a point on the imaging surface 160 relative to the center of the imaging surface 160. For the maximum field of view, the incident angle of the principal ray on the imaging surface 160 is 25.317°, and the maximum incident angle on the imaging surface 160 is less than 35°, indicating good angle control of the light rays.

[0081] Figure 7 The relative illumination distribution of the 3D imaging lens according to the first embodiment of the present invention on the imaging plane 160 is shown. The relative illumination of all fields of view is greater than 57.41%, which is much greater than the lower limit of 30%.

[0082] To fully illustrate the various embodiments of the present invention, other embodiments will be described below. It must be noted that the following embodiments use the same element reference numerals and some content as those in the foregoing embodiments, with the same reference numerals representing the same or similar elements, and descriptions of identical technical content omitted. For explanations of the omitted parts, please refer to the foregoing embodiments; these will not be repeated in the following embodiments.

[0083] Reference Figure 1 as well as Figure 8 ,in Figure 1 A schematic diagram of a polarization element according to some embodiments of the present invention is shown. Figure 8 A schematic diagram of a 3D imaging lens according to a second embodiment of the present invention is shown.

[0084] The 3D imaging lens 20 of the second embodiment of the present invention includes, in sequence along the optical axis I from the object side A1 to the image side A2, a first lens 210, a second lens 220, an aperture 230, a third lens 240, and a polarizing element 150. When light emitted from an object to be photographed enters the 3D imaging lens 20 and passes through the first lens 210, the second lens 220, the aperture 230, the third lens 240, and the polarizing element 150 in sequence, an image is formed on the imaging surface 260.

[0085] In this embodiment, the first lens 210, the second lens 220, the third lens 240 and the polarizing element 150 of the 3D imaging lens 20 each have an object side surface 211, 221, 241, 151 facing the object side A1 and allowing imaging light to pass through, and an image side surface 212, 222, 242, 152 facing the image side A2 and allowing imaging light to pass through.

[0086] The first lens 210 has negative refractive power. The optical axis region of the object-side surface 211 of the first lens 210 is concave, and its circumferential region is also concave. The optical axis region of the image-side surface 212 of the first lens 210 is concave, and its circumferential region is also concave. In this embodiment, both the object-side surface 211 and the image-side surface 212 of the first lens 210 are aspherical.

[0087] The second lens 220 has positive refractive power. The optical axis region of the object-side surface 221 of the second lens 220 is convex, and its circumferential region is also convex. The optical axis region of the image-side surface 222 of the second lens 220 is convex, and its circumferential region is concave. In this embodiment, both the object-side surface 221 and the image-side surface 222 of the second lens 220 are aspherical.

[0088] The third lens 240 has positive refractive power. The optical axis region of the object-side surface 241 of the third lens 240 is convex, and its circumferential region is also convex. The optical axis region of the image-side surface 242 of the third lens 240 is convex, and its circumferential region is concave. In this embodiment, both the object-side surface 241 and the image-side surface 242 of the third lens 240 are aspherical.

[0089] The polarization element 150 includes a plurality of optical units 150U arranged in an array. Each optical unit 150U includes a first polarization structure 151P, a second polarization structure 152P, and a third polarization structure 153P. When light passes through the first polarization structure 151P, first linearly polarized light is generated; when light passes through the second polarization structure 152P, second linearly polarized light is generated; and when light passes through the third polarization structure 153P, third linearly polarized light is generated. The first, second, and third linearly polarized lights are not parallel to each other. The first, second, and third polarization structures 151P, 152P, and 153P may be constructed, for example, by a metal wire grid, allowing only polarization components perpendicular to the direction of the metal wire grid to pass through, but are not limited thereto. Furthermore, a three-dimensional image can be obtained by using the obtained first, second, and third linearly polarized lights and by using Stokes vectors and the Frankot-Chellappa integral algorithm. In some preferred embodiments, the angle between any two of the first, second, and third linearly polarized light is 60 degrees. For example, the polarization direction of the first linearly polarized light is 60 degrees from a reference direction, the polarization direction of the second linearly polarized light is 120 degrees from the reference direction, and the polarization direction of the third linearly polarized light is 180 degrees from the reference direction, but this is not a limitation.

[0090] In some embodiments, the object distance of the 3D imaging lens 20 is greater than or equal to 10 mm, and it can be implemented as an endoscope or part of an endoscope. Each optical unit 150U of the polarization element 150 may also include a filter unit 154F, the operating wavelength of which covers the range of 470 nm to 650 nm, enabling the 3D imaging lens 20 to perform macro photography; or, the operating wavelength of the filter unit 154F may cover the range of 930 nm to 950 nm, enabling the 3D imaging lens 20 to improve the diagnostic accuracy of the endoscope and reduce surgical risks through positioning calculations of the navigation system.

[0091] Other detailed optical data for the second embodiment are shown in Table 3. The effective focal length (EFL) of the 3D imaging lens 20 in the second embodiment is 0.566 mm, the field of view (FOV) is 130°, the total track length (TTL) is 3.810 mm, the back focal length (BFL) is 0.209 mm, and the aperture (F-number) is 2.347. The image height is 1.264 mm, slightly larger than the diagonal length of the imaging plane 260 (1.23 mm) to avoid vignetting caused by packaging offset. The entrance pupil diameter is 0.241 mm, and the numerical aperture (NA) is 0.204.

[0092] Table 3:

[0093]

[0094] As shown in Table 3, the 3D imaging lens 20 satisfies the condition 2.0≥f1+f2+f3≥1.0, where f1 is the focal length of the first lens 210, f2 is the focal length of the second lens 220, and f3 is the focal length of the third lens 240.

[0095] As shown in Table 3, the 3D imaging lens 20 satisfies the condition -2.0≤1 / R1-1 / R2≤-1.0, where R1 is the radius of curvature of the object side 211 of the first lens 210 and R2 is the radius of curvature of the image side 212 of the first lens 210.

[0096] As shown in Table 3, the 3D imaging lens 20 satisfies the condition 1.5≥1 / R3-1 / R4≥0.5, where R3 is the radius of curvature of the object side 221 of the second lens 220 and R4 is the radius of curvature of the image side 222 of the second lens 220.

[0097] As shown in Table 3, the 3D imaging lens 20 satisfies the condition 1.9≥1 / R5-1 / R6≥0.9, where R5 is the radius of curvature of the object side 241 of the third lens 240 and R6 is the radius of curvature of the image side 242 of the third lens 240.

[0098] As shown in Table 3, the 3D imaging lens 20 satisfies the condition n2>n1=n3, where n1 is the refractive index of the first lens 210, n2 is the refractive index of the second lens 220, and n3 is the refractive index of the third lens 240.

[0099] As shown in Table 3, the 3D imaging lens 20 satisfies the condition 0.5>D1 / n1+D2 / n2+D3 / n3>0.2, where D1 is the diopter of the first lens 210, D2 is the diopter of the second lens 220, and D3 is the diopter of the third lens 240.

[0100] As shown in Table 3, the 3D imaging lens 20 satisfies the condition υ1=υ3>υ2, where υ1 is the Abbe number of the first lens 210, υ2 is the Abbe number of the second lens 220, and υ3 is the Abbe number of the third lens 240.

[0101] As shown in Table 3, the 3D imaging lens 20 satisfies the condition 0.005>D1 / ν1+D2 / ν2+D3 / ν3>0.002.

[0102] The 3D imaging lens 20 also satisfies the conditional TTL / SDL≥2.5 mm and the conditional TTL<3.9 mm, where TTL is the total length of the 3D imaging lens 20 and SDL is the diagonal length of the imaging plane 260 of the 3D imaging lens 20.

[0103] Furthermore, in this embodiment, the object side surfaces 211, 221, 241 and the image side surfaces 112, 122, 142 of the first lens 210, the second lens 220 and the third lens 240 are all aspherical surfaces, and these aspherical surfaces are defined according to formula (1).

[0104] The aspherical coefficients of the object-side surface 211 of the first lens 210 to the image-side surface 242 of the third lens 240 in formula (1) are shown in Table 4. In Table 4, column number 211 indicates that it is the aspherical coefficient of the object-side surface 211 of the first lens 210, and the other columns are deduced accordingly. The first lens 210, the second lens 220 and the third lens 240 are all even-order aspherical lenses.

[0105] Table 4:

[0106]

[0107] refer to Figure 9It shows the modulation transfer function (MTF) curve of the 3D imaging lens according to the second embodiment of the present invention to evaluate the resolution and sharpness of the 3D imaging lens 20. Figure 9 In the diagram, curve 0.0F_T represents the meridional direction of the central field of view (0° field of view angle), curve 0.0F_S represents the sagittal direction of the central field of view, curve 1.0F_T represents the meridional direction of the maximum field of view (130° field of view angle), curve 1.0F_S represents the sagittal direction of the maximum field of view, curve 0.5F_T represents the meridional direction of the half field of view (65° field of view angle), and curve 0.5F_S represents the sagittal direction of the half field of view. For example... Figure 9 As shown, for spatial frequencies greater than or equal to 125 lp / mm, the entire field of view exhibits a contrast ratio greater than 0.3. The 3D imaging lens 20 demonstrates excellent resolution and sharpness.

[0108] See also Figures 10A to 10C , Figure 10A and Figure 10B The field curvature aberrations of the 3D imaging lens 20 in the meridional direction and the sagittal direction are shown for wavelengths of 470 nm, 550 nm, 650 nm and 940 nm, respectively. Figure 10C This shows the distortion aberrations of the 3D imaging lens 20 at wavelengths of 470 nm, 550 nm, 650 nm, and 940 nm. For example... Figure 10A and Figure 10B As shown, the field curvature aberrations of the four representative wavelengths fall within ±0.05 mm across the entire field of view, indicating that the 3D imaging lens 20 can effectively eliminate aberrations. Figure 10C The maximum distortion rate of the 3D imaging lens 20 is 50.312%, indicating that the 3D imaging lens 20 can provide good imaging quality.

[0109] Figure 11 The lateral chromatic aberration and Airy disk of a 3D imaging lens according to a second embodiment of the present invention are shown. Figure 11 As shown, the maximum lateral chromatic aberration of the 3D imaging lens 20 is approximately 1.204 µm, indicating good chromatic aberration control.

[0110] Figure 12 The diagram illustrates the incident angle distribution of the 3D imaging lens on the imaging surface 260 according to a second embodiment of the present invention, where the horizontal axis represents the distance of a point on the imaging surface 260 relative to the center of the imaging surface 260. For the maximum field of view, the incident angle of the principal ray on the imaging surface 260 is 24.756°, and the maximum incident angle on the imaging surface 260 is less than 35°, indicating good angle control of the light rays.

[0111] Figure 13The relative illumination distribution of the 3D imaging lens according to the second embodiment of the present invention on the imaging plane 260 is shown. The relative illumination of all fields of view is greater than 59.38%, which is much greater than the lower limit of 30%.

[0112] Reference Figure 1 as well as Figure 14 ,in Figure 1 A schematic diagram of a polarization element according to some embodiments of the present invention is shown. Figure 14 A schematic diagram of a 3D imaging lens according to a third embodiment of the present invention is shown.

[0113] The 3D imaging lens 30 of the third embodiment of the present invention includes, in sequence along the optical axis I from the object side A1 to the image side A2, a first lens 310, a second lens 320, an aperture 330, a third lens 340, and a polarizing element 150. When light emitted from an object to be photographed enters the 3D imaging lens 30 and passes through the first lens 310, the second lens 320, the aperture 330, the third lens 340, and the polarizing element 150 in sequence, an image is formed on the imaging surface 360.

[0114] In this embodiment, the first lens 310, the second lens 320, the third lens 340 and the polarizing element 150 of the 3D imaging lens 30 each have an object side surface 311, 321, 341, 151 facing the object side A1 and allowing imaging light to pass through, and an image side surface 312, 322, 342, 152 facing the image side A2 and allowing imaging light to pass through.

[0115] The first lens 310 has negative refractive power. The optical axis region of the object-side surface 311 of the first lens 310 is concave, and its circumferential region is also concave. The optical axis region of the image-side surface 312 of the first lens 310 is concave, and its circumferential region is also concave. In this embodiment, both the object-side surface 311 and the image-side surface 312 of the first lens 310 are aspherical.

[0116] The second lens 320 has positive refractive power. The optical axis region of the object-side surface 321 of the second lens 320 is convex, and its circumferential region is also convex. The optical axis region of the image-side surface 322 of the second lens 320 is convex, and its circumferential region is also convex. In this embodiment, both the object-side surface 321 and the image-side surface 322 of the second lens 320 are aspherical.

[0117] The third lens 340 has positive refractive power. The optical axis region of the object-side surface 341 of the third lens 340 is convex, and its circumferential region is also convex. The optical axis region of the image-side surface 342 of the third lens 340 is convex, and its circumferential region is concave. In this embodiment, both the object-side surface 341 and the image-side surface 342 of the third lens 340 are aspherical.

[0118] The polarization element 150 includes a plurality of optical units 150U arranged in an array. Each optical unit 150U includes a first polarization structure 151P, a second polarization structure 152P, and a third polarization structure 153P. When light passes through the first polarization structure 151P, first linearly polarized light is generated; when light passes through the second polarization structure 152P, second linearly polarized light is generated; and when light passes through the third polarization structure 153P, third linearly polarized light is generated. The first, second, and third linearly polarized lights are not parallel to each other. The first, second, and third polarization structures 151P, 152P, and 153P may be constructed, for example, by a metal wire grid, allowing only polarization components perpendicular to the direction of the metal wire grid to pass through, but are not limited thereto. Furthermore, a three-dimensional image can be obtained by using the obtained first, second, and third linearly polarized lights and by using Stokes vectors and the Frankot-Chellappa integral algorithm. In some preferred embodiments, the angle between any two of the first, second, and third linearly polarized light is 60 degrees. For example, the polarization direction of the first linearly polarized light is 60 degrees from a reference direction, the polarization direction of the second linearly polarized light is 120 degrees from the reference direction, and the polarization direction of the third linearly polarized light is 180 degrees from the reference direction, but this is not a limitation.

[0119] In some embodiments, the object distance of the 3D imaging lens 30 is greater than or equal to 10 mm, and it can be implemented as an endoscope or part of an endoscope. Each optical unit 150U of the polarization element 150 may also include a filter unit 154F, the operating wavelength of which covers the range of 470 nm to 650 nm, enabling the 3D imaging lens 30 to perform macro photography; or, the operating wavelength of the filter unit 154F may cover the range of 930 nm to 950 nm, enabling the 3D imaging lens 30 to improve the diagnostic accuracy of the endoscope and reduce surgical risks through positioning calculations of the navigation system.

[0120] Other detailed optical data for the third embodiment are shown in Table 5. The effective focal length (EFL) of the 3D imaging lens 30 in the third embodiment is 0.431 mm, the field of view (FOV) is 122°, the total track length (TTL) is 3.875 mm, the back focal length (BFL) is 0.187 mm, and the aperture (F-number) is 2.200. The image height is 0.736 mm, slightly larger than the diagonal length of the imaging plane 360° (0.727 mm) to avoid vignetting caused by packaging offset. The entrance pupil diameter is 0.196 mm, and the numerical aperture (NA) is 0.218.

[0121] Table 5:

[0122]

[0123] As shown in Table 5, the 3D imaging lens 30 satisfies the condition 2.0≥f1+f2+f3≥1.0, where f1 is the focal length of the first lens 310, f2 is the focal length of the second lens 320, and f3 is the focal length of the third lens 340.

[0124] As shown in Table 5, the 3D imaging lens 30 satisfies the condition -2.0≤1 / R1-1 / R2≤-1.0, where R1 is the radius of curvature of the object side surface 311 of the first lens 310 and R2 is the radius of curvature of the image side surface 312 of the first lens 310.

[0125] As shown in Table 5, the 3D imaging lens 30 satisfies the condition 1.5≥1 / R3-1 / R4≥0.5, where R3 is the radius of curvature of the object side surface 321 of the second lens 320 and R4 is the radius of curvature of the image side surface 322 of the second lens 320.

[0126] As shown in Table 5, the 3D imaging lens 30 satisfies the condition 1.9≥1 / R5-1 / R6≥0.9, where R5 is the radius of curvature of the object side surface 341 of the third lens 340 and R6 is the radius of curvature of the image side surface 342 of the third lens 340.

[0127] As shown in Table 5, the 3D imaging lens 30 satisfies the condition n2>n1=n3, where n1 is the refractive index of the first lens 310, n2 is the refractive index of the second lens 320, and n3 is the refractive index of the third lens 340.

[0128] As shown in Table 5, the 3D imaging lens 30 satisfies the condition 0.5>D1 / n1+D2 / n2+D3 / n3>0.2, where D1 is the diopter of the first lens 310, D2 is the diopter of the second lens 320, and D3 is the diopter of the third lens 340.

[0129] As shown in Table 5, the 3D imaging lens 30 satisfies the condition υ1=υ3>υ2, where υ1 is the Abbe number of the first lens 310, υ2 is the Abbe number of the second lens 320, and υ3 is the Abbe number of the third lens 340.

[0130] As shown in Table 5, the 3D imaging lens 30 satisfies the condition 0.005>D1 / ν1+D2 / ν2+D3 / ν3>0.002.

[0131] The 3D imaging lens 30 also satisfies the conditional TTL / SDL≥2.5 mm and the conditional TTL<3.9 mm, where TTL is the total length of the 3D imaging lens 30 and SDL is the diagonal length of the imaging plane 360 ​​of the 3D imaging lens 30.

[0132] Furthermore, in this embodiment, the object side surfaces 311, 321, 341 and the image side surfaces 112, 122, 142 of the first lens 310, the second lens 320 and the third lens 340 are all aspherical surfaces, and these aspherical surfaces are defined according to formula (1).

[0133] The aspherical coefficients of the object-side surface 311 of the first lens 310 to the image-side surface 342 of the third lens 340 in formula (1) are shown in Table 6. In Table 6, column number 311 indicates that it is the aspherical coefficient of the object-side surface 311 of the first lens 310, and the other columns are deduced accordingly. The first lens 310, the second lens 320 and the third lens 340 are all even-order aspherical lenses.

[0134] Table 6:

[0135]

[0136] refer to Figure 15 It shows the modulation transfer function (MTF) curve of the 3D imaging lens according to the third embodiment of the present invention to evaluate the resolution and sharpness of the 3D imaging lens 30. Figure 15 In the diagram, curve 0.0F_T represents the meridional direction of the central field of view (0° field of view angle), curve 0.0F_S represents the sagittal direction of the central field of view, curve 1.0F_T represents the meridional direction of the maximum field of view (122° field of view angle), curve 1.0F_S represents the sagittal direction of the maximum field of view, curve 0.5F_T represents the meridional direction of the half field of view (61° field of view angle), and curve 0.5F_S represents the sagittal direction of the half field of view. For example... Figure 15As shown, for spatial frequencies greater than or equal to 125 lp / mm, the entire field of view exhibits a contrast ratio greater than 0.3. The 3D imaging lens 30 demonstrates excellent resolution and sharpness.

[0137] See also Figures 16A to 16C , Figure 16A and Figure 16B The field curvature aberrations of the 3D imaging lens 30 in the meridional direction and the sagittal direction are shown for wavelengths of 470 nm, 550 nm, 650 nm and 940 nm, respectively. Figure 16C This shows the distortion aberrations of the 3D imaging lens 30 at wavelengths of 470 nm, 550 nm, 650 nm, and 940 nm. For example... Figure 16A and Figure 16B As shown, the field curvature aberrations of the four representative wavelengths fall within the range of 0 mm to -0.15 mm across the entire field of view, indicating that the 3D imaging lens 30 can effectively eliminate aberrations. Figure 16C The maximum distortion rate of the 3D imaging lens 30 is 59.290%, indicating that the 3D imaging lens 30 can provide good imaging quality.

[0138] Figure 17 The lateral chromatic aberration and Airy disk of a 3D imaging lens according to a third embodiment of the present invention are shown. Figure 17 As shown, the maximum lateral chromatic aberration of the 3D imaging lens 30 is approximately 2.352 µm, indicating good chromatic aberration control.

[0139] Figure 18 The diagram illustrates the incident angle distribution of a 3D imaging lens on the imaging surface 360 ​​according to a third embodiment of the present invention, where the horizontal axis represents the distance of a point on the imaging surface 360 ​​relative to the center of the imaging surface 360. For the maximum field of view, the incident angle of the principal ray on the imaging surface 360 ​​is 18.307°, and the maximum incident angle on the imaging surface 360 ​​is less than 30°, indicating good angle control of the light rays.

[0140] Figure 19 The relative illumination distribution of the 3D imaging lens according to the third embodiment of the present invention is shown on the imaging plane 360. The relative illumination of all fields of view is greater than 84.54%, which is much greater than the lower limit of 30%.

[0141] In summary, the 3D imaging lens provided in this embodiment of the invention can provide spatial positioning and perform macro stereoscopic photography in a limited space, with high imaging quality.

Claims

1. A 3D imaging lens, characterized in that, From the object side to the image side along the optical axis, sequentially including: The first lens has a negative refractive power; The second lens has a positive refractive power; The third lens has a positive refractive power; and A polarization element includes a plurality of optical units arranged in an array, wherein each optical unit includes a first polarization structure, a second polarization structure, and a third polarization structure; when light passes through the first polarization structure, a first linearly polarized light is generated; when light passes through the second polarization structure, a second linearly polarized light is generated; when light passes through the third polarization structure, a third linearly polarized light is generated; the first linearly polarized light, the second linearly polarized light, and the third linearly polarized light are not parallel to each other.

2. The 3D imaging lens according to claim 1, characterized in that, The first lens is a biconcave lens.

3. The 3D imaging lens according to claim 1, characterized in that, The second lens is a biconvex lens.

4. The 3D imaging lens according to claim 1, characterized in that, The third lens is a biconvex lens.

5. The 3D imaging lens according to claim 1, characterized in that, At least one of the first lens, the second lens, and the third lens is an even-order aspherical lens.

6. The 3D imaging lens according to claim 5, characterized in that, The 3D imaging lens satisfies the condition TTL / SDL≥2.5 mm and the condition TTL<3.9 mm, where TTL is the total length of the 3D imaging lens and SDL is the diagonal length of the imaging plane of the 3D imaging lens.

7. The 3D imaging lens according to claim 1, characterized in that, The 3D imaging lens satisfies the condition 2.0≥f1+f2+f3≥1.0, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

8. The 3D imaging lens according to claim 1, characterized in that, The 3D imaging lens satisfies the condition -2.0≤1 / R1-1 / R2≤-1.0, where R1 is the radius of curvature of the object side of the first lens and R2 is the radius of curvature of the image side of the first lens.

9. The 3D imaging lens according to claim 1, characterized in that, The 3D imaging lens satisfies the condition 1.5≥1 / R3-1 / R4≥0.5, where R3 is the radius of curvature of the object side of the second lens and R4 is the radius of curvature of the image side of the second lens.

10. The 3D imaging lens according to claim 1, characterized in that, The 3D imaging lens satisfies the condition 1.9≥1 / R5-1 / R6≥0.9, where R5 is the radius of curvature of the object side of the third lens and R6 is the radius of curvature of the image side of the third lens.

11. The 3D imaging lens according to claim 1, characterized in that, The 3D imaging lens satisfies the condition n2>n1=n3, where n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, and n3 is the refractive index of the third lens.

12. The 3D imaging lens according to claim 11, characterized in that, The 3D imaging lens satisfies the condition 0.5>D1 / n1+D2 / n2+D3 / n3>0.2, where D1 is the diopter of the first lens, D2 is the diopter of the second lens, and D3 is the diopter of the third lens.

13. The 3D imaging lens according to claim 1, characterized in that, The 3D imaging lens satisfies the condition υ1=υ3>υ2, where υ1 is the Abbe number of the first lens, υ2 is the Abbe number of the second lens, and υ3 is the Abbe number of the third lens.

14. The 3D imaging lens according to claim 13, characterized in that, The 3D imaging lens satisfies the condition 0.005>D1 / ν1+D2 / ν2+D3 / ν3>0.002, where D1 is the diopter of the first lens, D2 is the diopter of the second lens, and D3 is the diopter of the third lens.

15. The 3D imaging lens according to claim 1, characterized in that, The f-number of the 3D imaging lens falls within the range of 2.0 to 4.

0.

16. The 3D imaging lens according to claim 1, characterized in that, The field of view of the 3D imaging lens is in the range of 122 degrees to 180 degrees.

17. The 3D imaging lens according to claim 1, characterized in that, The angle between any two of the first linearly polarized light, the second linearly polarized light, and the third linearly polarized light is 60 degrees.

18. The 3D imaging lens according to claim 1, characterized in that, Each of the optical units of the polarization element further includes a filter unit, the filter unit having an operating wavelength ranging from 470 nm to 650 nm.

19. The 3D imaging lens according to claim 1, characterized in that, Each of the optical units of the polarization element further includes a filter unit, the operating wavelength of which covers the range of 930 nm to 950 nm.

Images