Optical imaging system

Abstract

The present application discloses an optical imaging system, which includes: a first lens, a second lens, a third lens and a first prism which are arranged in sequence from the object side along a first direction, wherein the first prism reflects the light incident to the first prism along the first direction to emit from the first prism along a second direction; and a second prism which is arranged along the second direction, reflects the light emitted from the first prism and incident to the second prism along the second direction to emit from the second prism along a third direction, wherein the first direction, the second direction and the third direction are perpendicular to each other; and the total effective focal length f of the optical imaging system satisfies: f>20mm.

Description

Technical Field

[0001] The present application relates to the field of optical elements, and in particular, to an optical imaging system. Background Art

[0002] As the requirements for the imaging functions of miniaturized electronic products such as smartphones increase, the market has also put forward higher requirements for the hardware conditions of electrically coupled devices or complementary metal oxide semiconductor image sensors and the optical performance of imaging lenses. At present, miniaturized electronic product terminals such as smartphones tend to pursue higher optical zoom factors. When the optical zoom factor value increases, the magnification of the optical imaging system will increase, and it will be clearer when shooting distant scenes.

[0003] However, as the focal length of the system increases, the total optical length will also increase, which will have an adverse effect on the miniaturization of miniaturized electronic products such as smartphones. Summary of the invention

[0004] On the one hand, the present application provides such an optical imaging system. The optical imaging system includes: a first lens, a second lens, a third lens and a first prism arranged in sequence from the object side along a first direction, wherein the first prism reflects the light incident to the first prism along the first direction to be emitted from the first prism along the second direction; and a second prism arranged along the second direction reflects the light emitted from the first prism and incident to the second prism along the second direction to be emitted from the second prism along a third direction, wherein the first direction, the second direction and the third direction are perpendicular to each other. The total effective focal length f of the optical imaging system can satisfy: f>20mm.

[0005] In one embodiment, the total effective focal length f of the optical imaging system and the horizontal distance Tx of the optical imaging system in the third direction may satisfy: 2.0<f / Tx<4.0.

[0006] In one embodiment, the total effective focal length f of the optical imaging system and the horizontal distance Tz of the optical imaging system in the first direction may satisfy: 2.0<f / Tz<3.0.

[0007] In one embodiment, the total effective focal length f of the optical imaging system and half the diagonal length ImgH of the effective pixel area on the imaging plane of the optical imaging system may satisfy: f / ImgH≥10.

[0008] In one embodiment, the total effective focal length f of the optical imaging system and the entrance pupil diameter EPD of the optical imaging system may satisfy: 3.0<f / EPD≤4.0.

[0009] In one embodiment, at least one of the first lens, the second lens and the third lens may be a lens made of plastic material, and at least one mirror surface of the lens made of plastic material may be an aspherical mirror surface.

[0010] In one embodiment, the refractive index N1 of the first lens and the refractive index N3 of the third lens may satisfy: 0<N3-N1<0.3.

[0011] In one embodiment, the dispersion coefficient V1 of the first lens and the dispersion coefficient V3 of the third lens may satisfy: 0<V1-V3<5.0.

[0012] In one embodiment, the first lens has positive optical power; the second lens has negative optical power; and the third lens has positive optical power.

[0013] In one embodiment, the total effective focal length f of the optical imaging system and the effective focal length f1 of the first lens may satisfy: 0.8≤f / f1<1.2.

[0014] In one embodiment, the total effective focal length f of the optical imaging system and the effective focal length f2 of the second lens may satisfy: -2.0≤f / f2≤-1.0.

[0015] In one embodiment, the total effective focal length f of the optical imaging system and the effective focal length f3 of the third lens may satisfy: 1.0<f / f3<2.0.

[0016] In one embodiment, the total effective focal length f of the optical imaging system and the curvature radius R1 of the object-side surface of the first lens may satisfy: 3.0<f / R1<5.0.

[0017] In one embodiment, the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, and the center thickness CT3 of the third lens may satisfy: 1.0 mm<(CT1+CT2+CT3) / 3<1.5 mm.

[0018] By reasonably allocating the optical power, surface shape, center thickness of each lens and horizontal distance on each optical axis, the above optical imaging system has at least one beneficial effect of miniaturization, long focal length, good imaging quality, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0020] Figure 1A A schematic structural diagram of an optical imaging system according to Embodiment 1 of the present application on a YZ plane is shown;

[0021] Figure 1BA schematic structural diagram of an optical imaging system according to Embodiment 1 of the present application on the YX plane is shown;

[0022] FIG. 2A to FIG. 2D The axial chromatic aberration curve, astigmatism curve, distortion curve and magnification chromatic aberration curve of the optical imaging system of Example 1 are respectively shown;

[0023] Figure 3A A schematic diagram of the structure of an optical imaging system according to Embodiment 2 of the present application on the YZ plane is shown;

[0024] Figure 3B A schematic structural diagram of an optical imaging system according to Embodiment 2 of the present application on the YX plane is shown;

[0025] FIG. 4A to FIG. 4D The axial chromatic aberration curve, astigmatism curve, distortion curve and magnification chromatic aberration curve of the optical imaging system of Example 2 are respectively shown;

[0026] Figure 5A A schematic structural diagram of an optical imaging system according to Embodiment 3 of the present application on a YZ plane is shown;

[0027] Figure 5B A schematic structural diagram of an optical imaging system according to Embodiment 3 of the present application on the YX plane is shown;

[0028] FIG. 6A to FIG. 6D The axial chromatic aberration curve, astigmatism curve, distortion curve and magnification chromatic aberration curve of the optical imaging system of Example 3 are respectively shown;

[0029] Fig. 7A A schematic structural diagram of an optical imaging system according to Embodiment 4 of the present application on a YZ plane is shown;

[0030] Figure 7B A schematic structural diagram of an optical imaging system according to Embodiment 4 of the present application on the YX plane is shown;

[0031] FIG. 8A to FIG. 8D The axial chromatic aberration curve, astigmatism curve, distortion curve and magnification chromatic aberration curve of the optical imaging system of Example 4 are respectively shown;

[0032] Fig.9A A schematic structural diagram of an optical imaging system according to Embodiment 5 of the present application on a YZ plane is shown;

[0033] Fig. 9B A schematic diagram of the structure of an optical imaging system according to Embodiment 5 of the present application on the YX plane is shown; and

[0034] FIG. 10A to FIG. 10DThe axial chromatic aberration curve, astigmatism curve, distortion curve and magnification chromatic aberration curve of the optical imaging system of Example 5 are respectively shown. DETAILED DESCRIPTION

[0035] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0036] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0037] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0038] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0039] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0040] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] The features, principles and other aspects of the present application are described in detail below.

[0043] An optical imaging system according to an exemplary embodiment of the present application may include a first lens, a second lens, a third lens, a first prism, and a second prism.

[0044] According to an exemplary embodiment of the present application, the optical imaging system may include: a first lens, a second lens, a third lens and a first prism in sequence from the object side along the first direction. The three lenses and the first prism are arranged in sequence from the object side along the first direction. There may be a spacing distance between any two adjacent lenses from the first lens to the first prism. The first prism is arranged on one side of the image side of the third lens, and can reflect the light incident on the first prism along the first direction into the light emitted from the first prism along the second direction. That is, the incident light passes through the first lens, the second lens and the third lens from the object side in sequence from the first direction to the first prism, and the incident light is reflected from the reflection surface of the first prism to the first light emitted from the first prism along the second direction. The second prism may be arranged in the second direction. The first light may be incident on the second prism along the second direction. The first light is reflected from the reflection surface of the second prism to the second light emitted from the second prism along the third direction.

[0045] According to an exemplary embodiment of the present application, the first direction, the second direction, and the third direction are perpendicular to each other. By using a first prism to redirect the light path from the first direction to the second direction, the total length of the optical imaging system in the first direction can be shortened. By using a second prism to redirect the redirected light path to the third direction for a second time, the total length of the optical imaging system in the second direction can be shortened to meet the requirements of miniaturization.

[0046] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: f>20 mm, where f is the total effective focal length of the optical imaging system. More specifically, f may further satisfy: f>23 mm. Satisfying f>20 mm can meet the system optical zoom multiple requirement.

[0047] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 2.0<f / Tx<4.0, wherein f is the total effective focal length of the optical imaging system, and Tx is the horizontal distance of the optical imaging system in the third direction. Figure 1B As shown, Tx is the projection distance of the entire optical imaging system in the third direction. More specifically, f and Tx may further satisfy: 2.0<f / Tx<3.7. Satisfying 2.0<f / Tx<4.0 can meet the requirements of the volume limitation of the lens module.

[0048] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 2.0<f / Tz<3.0, wherein f is the total effective focal length of the optical imaging system, and Tz is the horizontal distance of the optical imaging system in the first direction. Figure 1A As shown, Tz is the projection distance of the entire optical imaging system in the first direction. More specifically, f and Tz may further satisfy: 2.1<f / Tz<2.6. Satisfying 2.0<f / Tz<3.0 can meet the requirements of the volume limitation of the lens module.

[0049] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: f / ImgH≥10, where f is the total effective focal length of the optical imaging system, and ImgH is half the diagonal length of the effective pixel area on the imaging surface of the optical imaging system. Satisfying f / ImgH≥10 can meet the requirement of equivalent focal length, thereby facilitating the realization of the desired optical zoom multiple.

[0050] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 3.0<f / EPD≤4.0, where f is the total effective focal length of the optical imaging system and EPD is the entrance pupil diameter of the optical imaging system. More specifically, f and EPD may further satisfy: 3.4<f / EPD≤4.0. Satisfying 3.0<f / EPD≤4.0 allows sufficient effective light flux to pass through the system, thereby improving the signal-to-noise ratio.

[0051] In an exemplary embodiment, at least one of the first lens, the second lens, and the third lens may be a lens made of plastic material, and at least one mirror surface of the lens made of plastic material may be an aspherical mirror surface. Using a lens made of plastic material and having an aspherical mirror surface can further reduce the on-axis spherical aberration of the system and the off-axis meridian coma while improving the design freedom.

[0052] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 0<N3-N1<0.3, where N1 is the refractive index of the first lens and N3 is the refractive index of the third lens. More specifically, N3 and N1 may further satisfy: 0.1<N3-N1<0.3. Satisfying 0<N3-N1<0.3 is beneficial to correcting the magnification chromatic aberration of the system.

[0053] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 0<V1-V3<5.0, wherein V1 is the dispersion coefficient of the first lens, and V3 is the dispersion coefficient of the third lens. More specifically, V1 and V3 may further satisfy: 3.3<V1-V3<3.6. Satisfying 0<V1-V3<5.0 is conducive to reducing the axial chromatic aberration of the system.

[0054] In an exemplary embodiment, the first lens may have positive optical power, the second lens may have negative optical power, and the third lens may have positive optical power. Reasonable distribution of the optical power distribution of the three lenses can ensure that the magnification chromatic aberration is within two pixel sizes of the sensor while meeting the effective focal length requirements.

[0055] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 0.8≤f / f1<1.2, where f is the total effective focal length of the optical imaging system and f1 is the effective focal length of the first lens. When 0.8≤f / f1<1.2 is satisfied, the on-axis spherical aberration of the system can be corrected.

[0056] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: -2.0≤f / f2≤-1.0, wherein f is the total effective focal length of the optical imaging system, and f2 is the effective focal length of the second lens. More specifically, f and f2 may further satisfy: -1.6≤f / f2≤-1.3. Satisfying -2.0≤f / f2≤-1.0 enables the second lens to correct the amount of meridian coma of the system while bearing negative optical power.

[0057] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 1.0<f / f3<2.0, where f is the total effective focal length of the optical imaging system, and f3 is the effective focal length of the third lens. More specifically, f and f3 may further satisfy: 1.3<f / f3<1.8. Satisfying 1.0<f / f3<2.0 can correct the off-axis Petzval field curvature and meridional astigmatism.

[0058] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 3.0<f / R1<5.0, wherein f is the total effective focal length of the optical imaging system, and R1 is the radius of curvature of the object side of the first lens. More specifically, f and R1 may further satisfy: 3.3<f / R1<4.5. Satisfying 3.0<f / R1<5.0 can ensure the processability of the molding surface of the object side of the lens for large-diameter lenses, and also help reduce the amount of arc loss astigmatism of the system.

[0059] In an exemplary embodiment, the optical imaging system according to the present application may satisfy: 1.0mm<(CT1+CT2+CT3) / 3<1.5mm, wherein CT1 is the center thickness of the first lens, CT2 is the center thickness of the second lens, and CT3 is the center thickness of the third lens. More specifically, CT1, CT2, and CT3 may further satisfy: 1.1mm<(CT1+CT2+CT3) / 3<1.4mm. Satisfying 1.0mm<(CT1+CT2+CT3) / 3<1.5mm can constrain the center thickness of the three lenses within a reasonable range, which is beneficial to reducing the amount of surface error after lens molding and improving the processability of the lens.

[0060] In an exemplary embodiment, the optical imaging system according to the present application further includes an aperture provided between the object side and the first lens. Optionally, the optical imaging system may further include a filter for correcting color deviation and / or a protective glass for protecting a photosensitive element located on the imaging surface.

[0061] The optical imaging system according to the above-mentioned embodiment of the present application may use multiple lenses, such as the three lenses described above. By reasonably allocating the focal length, surface shape, center thickness of each lens, and axial spacing between lenses, etc., the incident light can be effectively converged, the total length of the optical imaging system can be reduced, and the processability of the optical imaging system can be improved, so that the structure of each lens is more compact, the optical imaging system is more conducive to production and processing, and has higher practicality. Through the above configuration, the optical imaging system according to the exemplary embodiment of the present application can have characteristics such as long focal length and good imaging quality.

[0062] In an embodiment of the present application, at least one of the mirror surfaces from the object side of the first lens to the image side of the third lens is an aspherical mirror surface. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality. Optionally, the object side and image side of each lens in the first lens and the second lens are aspherical mirror surfaces.

[0063] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the optical imaging system can be changed to obtain the various results and advantages described in this specification. For example, although three lenses are used as an example in the embodiment, the optical imaging system is not limited to including three lenses. If necessary, the optical imaging system may also include other numbers of lenses.

[0064] Specific embodiments of the optical imaging system applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0065] Example 1

[0066] The following reference Figures 1A to 2D An optical imaging system according to Example 1 of the present application is described. Figure 1A A schematic structural diagram of the optical imaging system according to Example 1 of the present application on the YZ plane is shown. Figure 1B A schematic structural diagram of the optical imaging system according to Example 1 of the present application on the YX plane is shown.

[0067] like Figure 1A and Figure 1B As shown, the optical imaging system includes, in order from the object side along the first direction Z: an aperture STO, a first lens E1, a second lens E2, a third lens E3 and a first prism P1. The incident light passes through the aperture STO, the first lens E1, the second lens E2 and the third lens E3 from the object side in the first direction Z to the first prism P1. The optical imaging system includes, in order, a first prism P1 and a second prism P2 along the second direction Y. The incident light is reflected by the first prism P1 to form a first light. The first light is directed in the second direction Y. The optical imaging system includes, in order, a second prism P2, a filter E4 and an imaging surface S15 along the third direction X. The first light is incident on the second prism P2 along the second direction Y. The first light is reflected by the second prism P2 to form a second light. The second light is directed in the third direction X.

[0068] The first lens E1 has positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex. The first prism P1 has an object side surface S7 parallel to the first direction Z, an image side surface S8 parallel to the second direction Y, and a reflection surface S9 parallel to the YZ plane. The second prism P2 has an object side surface S10 parallel to the third direction X, a reflection surface S11 parallel to the YX plane, and an image side surface S12 parallel to the second direction Y. The filter E4 has an object side surface S13 and an image side surface S14. The light from the object passes through each surface S1 to S14 in sequence and is finally imaged on the imaging surface S15.

[0069] Table 1 shows a basic parameter table of the optical imaging system of Example 1, wherein the units of the radius of curvature, thickness / distance and focal length are all millimeters (mm).

[0070]

[0071] Table 1

[0072] In this example, the total effective focal length f of the optical imaging system is 24.11 mm, and the maximum field of view FOV of the optical imaging system is 10.5°.

[0073] In Embodiment 1, the object side surface and the image side surface of any lens among the first lens E1 to the second lens E2 are both aspherical surfaces, and the surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0074]

[0075] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 below gives the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, 10 , A 12 , A 14 and A 16 .

[0076] Face number A4 A6 A8 A10 A12 A14 A16 S1 6.5297E-02 -8.0546E-03 -5.1662E-04 -9.8374E-05 2.3295E-05 -1.6732E-05 -9.1015E-06 S2 1.6210E-01 -4.4820E-02 -1.2864E-03 -1.6890E-03 -1.1554E-03 -1.1222E-03 -2.5654E-04 S3 -2.7407E-01 3.0958E-02 1.0465E-03 -5.3436E-03 -5.1781E-03 -2.8149E-03 -5.7826E-04 S4 -4.6483E-01 3.1326E-02 -4.2333E-04 1.2031E-03 8.3996E-05 -3.5857E-05 -5.7552E-05

[0077] Table 2

[0078] Figure 2A The axial chromatic aberration curve of the optical imaging system of Example 1 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 2B An astigmatism curve of the optical imaging system of Example 1 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 2C The distortion curve of the optical imaging system of Example 1 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Figure 2D The magnification chromatic aberration curve of the optical imaging system of Example 1 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. FIG. 2A to FIG. 2D It can be seen that the optical imaging system provided in Example 1 can achieve good imaging quality.

[0079] Example 2

[0080] The following reference FIG. 3A to FIG. 4D The optical imaging system according to Embodiment 2 of the present application is described. In this embodiment and the following embodiments, for the sake of brevity, some descriptions similar to Embodiment 1 will be omitted. Figure 3A A schematic structural diagram of the optical imaging system according to Example 2 of the present application on the YZ plane is shown. Figure 3BA schematic structural diagram of the optical imaging system according to Example 2 of the present application on the YX plane is shown.

[0081] like Figure 3A and Figure 3B As shown, the optical imaging system includes, in order from the object side along the first direction Z: an aperture STO, a first lens E1, a second lens E2, a third lens E3 and a first prism P1. The incident light passes through the aperture STO, the first lens E1, the second lens E2 and the third lens E3 from the object side in the first direction Z to the first prism P1. The optical imaging system includes, in order, a first prism P1 and a second prism P2 along the second direction Y. The incident light is reflected by the first prism P1 to form a first light. The first light is directed in the second direction Y. The optical imaging system includes, in order, a second prism P2, a filter E4 and an imaging surface S15 along the third direction X. The first light is incident on the second prism P2 along the second direction Y. The first light is reflected by the second prism P2 to form a second light. The second light is directed in the third direction X.

[0082] The first lens E1 has positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex. The first prism P1 has an object side surface S7 parallel to the first direction Z, an image side surface S8 parallel to the second direction Y, and a reflection surface S9 parallel to the YZ plane. The second prism P2 has an object side surface S10 parallel to the third direction X, a reflection surface S11 parallel to the YX plane, and an image side surface S12 parallel to the second direction Y. The filter E4 has an object side surface S13 and an image side surface S14. The light from the object passes through each surface S1 to S14 in sequence and is finally imaged on the imaging surface S15.

[0083] In this example, the total effective focal length f of the optical imaging system is 23.99 mm, and the maximum field of view FOV of the optical imaging system is 10.5°.

[0084] Table 3 shows the basic parameters of the optical imaging system of Example 2, wherein the units of the radius of curvature, thickness / distance and focal length are all in millimeters (mm). Table 4 shows the high-order coefficients of each aspherical mirror surface that can be used in Example 2, wherein the surface type of each aspherical surface can be defined by the formula (1) given in the above Example 1.

[0085]

[0086]

[0087] Table 3

[0088] Face number A4 A6 A8 A10 A12 A14 A16 S1 6.6043E-02 -7.8491E-03 -5.3950E-04 -1.0126E-04 1.6495E-05 -1.7002E-05 -5.1282E-06 S2 1.6162E-01 -4.4118E-02 -1.4435E-03 -1.3062E-03 -1.1831E-03 -9.8481E-04 -2.3654E-04 S3 -2.7266E-01 3.1717E-02 4.9444E-04 -5.3585E-03 -5.3033E-03 -2.6805E-03 -5.8399E-04 S4 -4.6160E-01 3.0748E-02 -8.0557E-04 8.7550E-04 -8.0402E-05 -9.1352E-05 -6.5150E-05

[0089] Table 4

[0090] Figure 4A The axial chromatic aberration curve of the optical imaging system of Example 2 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 4B An astigmatism curve of the optical imaging system of Example 2 is shown, which represents the meridional field curvature and the sagittal field curvature. Figure 4C The distortion curve of the optical imaging system of Example 2 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Figure 4D The magnification chromatic aberration curve of the optical imaging system of Example 2 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. FIG. 4A to FIG. 4D It can be seen that the optical imaging system provided in Example 2 can achieve good imaging quality.

[0091] Example 3

[0092] The following reference 5A to 6D An optical imaging system according to Example 3 of the present application is described. Figure 5A A schematic structural diagram of the optical imaging system according to Example 3 of the present application on the YZ plane is shown. Figure 5B A schematic structural diagram of the optical imaging system according to Example 3 of the present application on the YX plane is shown.

[0093] like Figure 5A and Figure 5B As shown, the optical imaging system includes, in order from the object side along the first direction Z: an aperture STO, a first lens E1, a second lens E2, a third lens E3 and a first prism P1. The incident light passes through the aperture STO, the first lens E1, the second lens E2 and the third lens E3 from the object side in the first direction Z to the first prism P1. The optical imaging system includes, in order, a first prism P1 and a second prism P2 along the second direction Y. The incident light is reflected by the first prism P1 to form a first light. The first light is directed in the second direction Y. The optical imaging system includes, in order, a second prism P2, a filter E4 and an imaging surface S15 along the third direction X. The first light is incident on the second prism P2 along the second direction Y. The first light is reflected by the second prism P2 to form a second light. The second light is directed in the third direction X.

[0094] The first lens E1 has positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex. The first prism P1 has an object side surface S7 parallel to the first direction Z, an image side surface S8 parallel to the second direction Y, and a reflection surface S9 parallel to the YZ plane. The second prism P2 has an object side surface S10 parallel to the third direction X, a reflection surface S11 parallel to the YX plane, and an image side surface S12 parallel to the second direction Y. The filter E4 has an object side surface S13 and an image side surface S14. The light from the object passes through each surface S1 to S14 in sequence and is finally imaged on the imaging surface S15.

[0095] In this example, the total effective focal length f of the optical imaging system is 29.50 mm, and the maximum field of view FOV of the optical imaging system is 10.0°.

[0096] Table 5 shows the basic parameters of the optical imaging system of Example 3, wherein the units of the radius of curvature, thickness / distance and focal length are all in millimeters (mm). Table 6 shows the high-order coefficients of each aspherical mirror surface that can be used in Example 3, wherein the surface type of each aspherical surface can be defined by the formula (1) given in the above Example 1.

[0097]

[0098] Table 5

[0099] Face number A4 A6 A8 A10 A12 A14 A16 S1 8.0833E-02 -9.3551E-03 -7.3716E-04 -1.9345E-04 3.6297E-06 1.1534E-05 -1.1427E-05 S2 1.9579E-01 -5.3230E-02 -1.8760E-03 -1.5786E-03 -1.3265E-03 -1.3057E-03 -4.7124E-04 S3 -3.3501E-01 4.3039E-02 5.6491E-04 -6.2847E-03 -6.1387E-03 -3.2378E-03 -7.8874E-04 S4 -5.4251E-01 4.0017E-02 -2.0157E-03 6.6949E-04 -8.3860E-05 5.1700E-05 1.0025E-05

[0100] Table 6

[0101] Fig. 6A The axial chromatic aberration curve of the optical imaging system of Example 3 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 6B An astigmatism curve of the optical imaging system of Example 3 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 6C The distortion curve of the optical imaging system of Example 3 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Fig.6D The magnification chromatic aberration curve of the optical imaging system of Example 3 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. FIG. 6A to FIG. 6D It can be seen that the optical imaging system provided in Example 3 can achieve good imaging quality.

[0102] Example 4

[0103] The following reference 7A to 8D An optical imaging system according to Example 4 of the present application is described. Fig. 7A A schematic structural diagram of the optical imaging system according to Example 4 of the present application on the YZ plane is shown. Figure 7B A schematic structural diagram of the optical imaging system according to Example 4 of the present application on the YX plane is shown.

[0104] like Fig. 7A and Figure 7B As shown, the optical imaging system includes, in order from the object side along the first direction Z: an aperture STO, a first lens E1, a second lens E2, a third lens E3 and a first prism P1. The incident light passes through the aperture STO, the first lens E1, the second lens E2 and the third lens E3 from the object side in the first direction Z to the first prism P1. The optical imaging system includes, in order, a first prism P1 and a second prism P2 along the second direction Y. The incident light is reflected by the first prism P1 to form a first light. The first light is directed in the second direction Y. The optical imaging system includes, in order, a second prism P2, a filter E4 and an imaging surface S15 along the third direction X. The first light is incident on the second prism P2 along the second direction Y. The first light is reflected by the second prism P2 to form a second light. The second light is directed in the third direction X.

[0105] The first lens E1 has positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex. The first prism P1 has an object side surface S7 parallel to the first direction Z, an image side surface S8 parallel to the second direction Y, and a reflection surface S9 parallel to the YZ plane. The second prism P2 has an object side surface S10 parallel to the third direction X, a reflection surface S11 parallel to the YX plane, and an image side surface S12 parallel to the second direction Y. The filter E4 has an object side surface S13 and an image side surface S14. The light from the object passes through each surface S1 to S14 in sequence and is finally imaged on the imaging surface S15.

[0106] In this example, the total effective focal length f of the optical imaging system is 30.46 mm, and the maximum field of view FOV of the optical imaging system is 7.7°.

[0107] Table 7 shows the basic parameters of the optical imaging system of Example 4, wherein the units of the radius of curvature, thickness / distance and focal length are all in millimeters (mm). Table 8 shows the high-order coefficients of each aspherical mirror surface that can be used in Example 4, wherein each aspherical surface type can be defined by the formula (1) given in the above Example 1.

[0108]

[0109]

[0110] Table 7

[0111] Face number A4 A6 A8 A10 A12 A14 A16 S1 6.2905E-02 -9.0382E-03 -2.9032E-03 7.5816E-04 -3.4000E-04 1.5536E-04 -3.4162E-05 S2 1.5807E-01 -5.5029E-02 -2.0859E-03 1.5950E-04 -1.0671E-03 3.6984E-04 -3.8290E-04 S3 -2.8596E-01 2.3487E-02 1.7364E-03 -2.9479E-03 -1.2391E-03 -6.6240E-04 -4.7552E-04 S4 -4.5618E-01 3.3071E-02 -1.2431E-03 -6.3517E-04 2.6987E-04 -1.7892E-04 3.2553E-05

[0112] Table 8

[0113] Fig. 8A The axial chromatic aberration curve of the optical imaging system of Example 4 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Figure 8B An astigmatism curve of the optical imaging system of Example 4 is shown, which indicates meridional field curvature and sagittal field curvature. Figure 8C The distortion curve of the optical imaging system of Example 4 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Fig.8D The magnification chromatic aberration curve of the optical imaging system of Example 4 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. FIG. 8A to FIG. 8D It can be seen that the optical imaging system provided in Example 4 can achieve good imaging quality.

[0114] Example 5

[0115] The following reference 9A to 10D An optical imaging system according to Example 5 of the present application is described. Fig.9A A schematic structural diagram of the optical imaging system according to Example 5 of the present application on the YZ plane is shown. Fig. 9B A schematic structural diagram of the optical imaging system according to Example 5 of the present application on the YX plane is shown.

[0116] like Fig.9A and Fig. 9B As shown, the optical imaging system includes, in order from the object side along the first direction Z: an aperture STO, a first lens E1, a second lens E2, a third lens E3 and a first prism P1. The incident light passes through the aperture STO, the first lens E1, the second lens E2 and the third lens E3 from the object side in the first direction Z to the first prism P1. The optical imaging system includes, in order, a first prism P1 and a second prism P2 along the second direction Y. The incident light is reflected by the first prism P1 to form a first light. The first light is directed in the second direction Y. The optical imaging system includes, in order, a second prism P2, a filter E4 and an imaging surface S15 along the third direction X. The first light is incident on the second prism P2 along the second direction Y. The first light is reflected by the second prism P2 to form a second light. The second light is directed in the third direction X.

[0117] The first lens E1 has positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave. The second lens E2 has negative optical power, its object side surface S3 is convex, and its image side surface S4 is concave. The third lens E3 has positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex. The first prism P1 has an object side surface S7 parallel to the first direction Z, an image side surface S8 parallel to the second direction Y, and a reflection surface S9 parallel to the YZ plane. The second prism P2 has an object side surface S10 parallel to the third direction X, a reflection surface S11 parallel to the YX plane, and an image side surface S12 parallel to the second direction Y. The filter E4 has an object side surface S13 and an image side surface S14. The light from the object passes through each surface S1 to S14 in sequence and is finally imaged on the imaging surface S15.

[0118] In this example, the total effective focal length f of the optical imaging system is 24.48 mm, and the maximum field of view FOV of the optical imaging system is 10.0°.

[0119] Table 9 shows the basic parameter table of the optical imaging system of Example 5, wherein the units of the radius of curvature, thickness / distance and focal length are all in millimeters (mm). Table 10 shows the high-order coefficients that can be used for each aspherical mirror surface in Example 5, wherein each aspherical surface type can be defined by the formula (1) given in the above Example 1.

[0120]

[0121] Table 9

[0122] Face number A4 A6 A8 A10 A12 A14 A16 S1 4.8041E-02 -8.6367E-03 -3.4425E-04 -1.1684E-04 -4.7874E-05 -8.8333E-06 -2.2084E-05 S2 1.6274E-01 -3.5786E-02 -3.3781E-03 -2.5559E-03 -1.2350E-03 -2.6050E-04 8.0233E-06 S3 -2.5660E-01 9.0797E-03 -2.7057E-03 -1.1967E-03 -5.7609E-04 1.8752E-04 2.0950E-04 S4 -4.6761E-01 1.7295E-02 -1.9065E-03 7.1592E-04 2.4345E-04 2.1210E-04 1.0774E-04

[0123] Table 10

[0124] Fig. 10A The axial chromatic aberration curve of the optical imaging system of Example 5 is shown, which indicates that light of different wavelengths deviates from the focal point behind the lens. Fig. 10B An astigmatism curve of the optical imaging system of Example 5 is shown, which indicates meridional field curvature and sagittal field curvature. Fig. 10C The distortion curve of the optical imaging system of Example 5 is shown, which represents the distortion magnitude values ​​corresponding to different image heights. Fig. 10D The magnification chromatic aberration curve of the optical imaging system of Example 5 is shown, which represents the deviation of different image heights on the imaging surface after the light passes through the lens. FIG. 10A to FIG. 10D It can be seen that the optical imaging system provided in Example 5 can achieve good imaging quality.

[0125] In summary, Examples 1 to 5 respectively satisfy the relationships shown in Table 11.

[0126] Conditional / Example 1 2 3 4 5 f / Tx 2.74 2.77 2.56 2.10 3.65 f / Tz 2.31 2.30 2.41 2.54 2.15 f / I 10.91 10.91 11.43 14.93 11.39 f / EPD 3.80 3.82 3.97 3.81 3.43 N3-N1 0.20 0.20 0.20 0.20 0.20 V1-V3 3.46 3.46 3.46 3.46 3.46 f / f1 0.86 0.86 0.90 1.09 0.84 f / f2 -1.39 -1.38 -1.34 -1.50 -1.47 f / f3 1.57 1.56 1.47 1.38 1.66 f / R1 3.60 3.58 3.72 4.44 3.33 (CT1+CT2+CT3) / 3(mm) 1.19 1.20 1.35 1.12 1.28

[0127] Table 11

[0128] The present application also provides an imaging device, whose electronic photosensitive element can be a photosensitive coupled device (CCD) or a complementary metal oxide semiconductor element (CMOS). The imaging device can be an independent imaging device such as a digital camera, or an imaging module integrated in a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical imaging system described above.

[0129] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. An optical imaging system, characterized in that: The optical imaging system comprises: A first lens, a second lens, a third lens, and a first prism are sequentially arranged along a first direction from an object side, wherein the first prism reflects light incident on the first prism along the first direction to be emitted from the first prism along a second direction; and The second prism disposed along the second direction reflects the light emitted from the first prism and incident on the second prism along the second direction to be emitted from the second prism along a third direction, wherein the first direction, the second direction and the third direction are perpendicular to each other; The first lens has positive refractive power, its object side surface is convex, and its image side surface is concave; The second lens has negative optical power, and its object side surface is convex and its image side surface is concave; The third lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The number of lenses having optical power in the optical imaging system is three; The total effective focal length f of the optical imaging system satisfies: 23.99 mm ≤ f ≤ 30.46 mm; The total effective focal length f of the optical imaging system and the horizontal distance Tz of the optical imaging system in the first direction satisfy: 2.15≤f / Tz≤2.54; The center thickness CT1 of the first lens, the center thickness CT2 of the second lens, and the center thickness CT3 of the third lens satisfy: 1.1 mm<(CT1+CT2+CT3) / 3≤1.35 mm.

2. The optical imaging system according to claim 1, characterized in that: The total effective focal length f of the optical imaging system and the horizontal distance Tx of the optical imaging system in the third direction satisfy: 2.10≤f / Tx≤3.

65.

3. The optical imaging system according to claim 1, characterized in that: A refractive index N1 of the first lens and a refractive index N3 of the third lens satisfy: 0.20≤N3-N1<0.

3.

4. The optical imaging system according to claim 1, characterized in that: The dispersion coefficient V1 of the first lens and the dispersion coefficient V3 of the third lens satisfy: 3.46≤V1-V3<3.

6.

5. The optical imaging system according to claim 1, characterized in that: The total effective focal length f of the optical imaging system and the effective focal length f1 of the first lens satisfy: 0.8<f / f1≤1.

09.

6. The optical imaging system according to claim 1, characterized in that: The total effective focal length f of the optical imaging system and the effective focal length f2 of the second lens satisfy: -1.50≤f / f2<-1.

3.

7. The optical imaging system according to claim 1, characterized in that: The total effective focal length f of the optical imaging system and the effective focal length f3 of the third lens satisfy: 1.38≤f / f3≤1.

66.

8. The optical imaging system according to claim 1, characterized in that: The total effective focal length f of the optical imaging system and the curvature radius R1 of the object side surface of the first lens satisfy: 3.3<f / R1≤4.

44.

9. The optical imaging system according to any one of claims 1 to 8, characterized in that: The total effective focal length f of the optical imaging system and half the diagonal length ImgH of the effective pixel area on the imaging surface of the optical imaging system satisfy the following: 10.91≤f / ImgH≤14.

93.

10. The optical imaging system according to any one of claims 1 to 8, characterized in that: The total effective focal length f of the optical imaging system and the entrance pupil diameter EPD of the optical imaging system satisfy: 3.4<f / EPD<4.

0.

11. The optical imaging system according to any one of claims 1 to 8, characterized in that: At least one of the first lens, the second lens and the third lens is a lens made of plastic material, and at least one mirror surface of the lens made of plastic material is an aspherical mirror surface.

Images