Reducing and refracting mixed high-image-quality lens

Abstract

The invention discloses a diffractive hybrid high-image-quality lens, and the lens sequentially comprises a first lens with negative focal power from an object side to an image side along an optical axis, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with negative focal power and a fifth lens with negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a convex surface; the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a concave surface; the lens at least comprises an aspheric lens. A diaphragm is arranged between the first lens and the second lens. The five aspherical lenses in specific shapes are adopted, through reasonable matching of the surface types and the focal power of all the lenses and reasonable arrangement of the position of the diaphragm, the system can have high image quality and low chromatic aberration, the full field angle reaches 110 degrees or above, and the distortion of the system is lower than 2%.

Description

Technical Field

[0001] The present invention relates to the field of optical lens structures, and in particular to a diffractive-refractive hybrid high-image-quality lens. Background Art

[0002] With the continuous advancement of technology, the rapid development of mobile communications and short video platforms, shooting has become a daily routine, and recording life anytime and anywhere is becoming more and more common. At the same time, the consumer market has also put forward new requirements for lenses. Equipment is becoming increasingly light and portable, and the requirements for image quality are getting higher and higher, while also having to be low in cost. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-quality diffractive-refractive hybrid lens to solve the above problems, so as to address the problems of high cost and poor performance of existing lenses.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a diffractive-refractive hybrid high-image-quality lens, comprising, from the object side to the image side, along the optical axis:

[0005] The first lens has a negative optical power, a concave object-side surface and a convex image-side surface;

[0006] a second lens having positive optical power, a convex object-side surface and a convex image-side surface;

[0007] The third lens has negative optical power, with a convex object-side surface and a concave image-side surface;

[0008] The fourth lens element has positive optical power, a concave object-side surface and a convex image-side surface;

[0009] The fifth lens element has positive optical power, a convex object-side surface and a concave image-side surface;

[0010] The lens comprises at least one aspherical lens.

[0011] Preferably, a stop is provided between the first lens and the second lens.

[0012] Preferably, the fifth lens is a diffractive element, and both the object-side surface and the image-side surface are diffractive surfaces, and satisfy the following conditional formula:

[0013]

[0014] Wherein, M is the diffraction order, N is the diffraction surface polynomial order, Ai is the diffraction surface multi-term coefficient, ρ is the diffraction surface diameter, and the lens satisfies: M=1, N=16, -1 <A4<3、-1<A6<3、-1<A8<0、-3<A10<2、0<A12<2、-2<A14<2,-3<A16<3。

[0015] Preferably, the lens satisfies the following conditional formula:

[0016] -1 <R1 / R2<1.5;

[0017] -3 <R3 / R4<2;

[0018] 0 <R5 / R6<3;

[0019] -1 <R7 / R8<2;

[0020] Wherein, R1 is the radius of curvature of the objective side of the first lens,

[0021] R2 is the curvature radius of the image side of the first lens,

[0022] R3 is the radius of curvature of the second lens objective side,

[0023] R4 is the curvature radius of the image side of the second lens,

[0024] R5 is the radius of curvature of the object side of the third lens,

[0025] R6 is the curvature radius of the image side of the third lens,

[0026] R7 is the radius of curvature of the object side of the fourth lens,

[0027] R8 is the curvature radius of the image-side surface of the fourth lens.

[0028] Preferably, the lens satisfies the following conditional formula:

[0029] 0.85 <FNO / ENPD<1.8;

[0030] Wherein, FNO is the aperture of the lens, and ENPD is the entrance pupil diameter of the lens.

[0031] Preferably, the lens satisfies the following conditional formula:

[0032] 3.1 <TTL / tanHFOV<3.5;

[0033] Wherein, TTL is the on-axis distance from the object side of the first lens to the imaging surface,

[0034] HFOV is the half field of view angle of the maximum field of view of the lens.

[0035] Preferably, the lens satisfies the following conditional formula:

[0036] DFOV ≥ 110°,

[0037] Wherein, DFOV is the full field of view of the lens.

[0038] Preferably, the lens satisfies the following conditional formula:

[0039] 50≤Vd1≤60,

[0040] 50≤Vd2≤60,

[0041] 20≤Vd3≤30,

[0042] 20≤Vd4≤61,

[0043] 20≤Vd5≤30,

[0044] Wherein, Vd1 is the Abbe number of the first lens,

[0045] Vd2 is the Abbe number of the second lens,

[0046] Vd3 is the Abbe number of the third lens,

[0047] Vd4 is the Abbe number of the fourth lens,

[0048] Vd5 is the Abbe number of the fifth lens.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention discloses a refractive-diffractive hybrid high-image-quality lens system that utilizes five aspherical lenses of specific shapes. By rationally matching the surface shapes and optical powers of the lenses and properly positioning the aperture, the system achieves high image quality, low chromatic aberration, a full field of view exceeding 110°, and system distortion below 2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 The lens cross section and optical path diagram of the diffractive-refractive hybrid high-image-quality lens of Example 1;

[0053] Figure 2 : This is a field curvature distortion diagram of the diffractive-refractive hybrid high-image-quality lens of Example 1;

[0054] Figure 3 : This is the MTF diagram of the diffractive-refractive hybrid high-image-quality lens of Example 1;

[0055] Figure 4 1 is a point diagram of the diffractive-refractive hybrid high-image-quality lens of Example 1;

[0056] Figure 5 chromatic aberration diagram of the diffractive-refractive hybrid high-image-quality lens of Example 1;

[0057] Figure 6 The lens cross section and optical path diagram of the diffractive-refractive hybrid high-image-quality lens of Example 2;

[0058] Figure 7 : This is a field curvature distortion diagram of the diffractive-refractive hybrid high-quality lens of Example 2;

[0059] Figure 8 This is the MTF diagram of the diffractive-refractive hybrid high-image-quality lens of Example 2;

[0060] Figure 9 1 is a spot diagram of the diffractive-refractive hybrid high-image-quality lens of Example 2;

[0061] Figure 10 chromatic aberration diagram of the diffractive-refractive hybrid high-image-quality lens of Example 2;

[0062] Figure 11 The lens cross section and optical path diagram of the diffractive-refractive hybrid high-image-quality lens of Example 3;

[0063] Figure 12 : This is a field curvature distortion diagram of the diffractive-refractive hybrid high-image-quality lens of Example 3;

[0064] Figure 13 This is the MTF diagram of the diffractive-refractive hybrid high-image-quality lens of Example 3;

[0065] Figure 14 1 is a point diagram of the diffractive-refractive hybrid high-image-quality lens of Example 3;

[0066] Figure 15 This is a chromatic aberration diagram of the diffractive-refractive hybrid high-quality lens in Example 3. DETAILED DESCRIPTION

[0067] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other implementations obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0068] like Figure 1As shown, a refractive-diffractive hybrid high-image-quality lens of the present invention consists of five lenses, with a simple structure, small size, low distortion, high image quality, and low chromatic aberration. By combining lenses with different structures and diffractive elements and reasonably distributing the optical powers of each lens, it is possible to ensure high image quality while having low distortion, low chromatic aberration, and a large field angle. Along the optical axis from the object side to the image side, it sequentially includes a first lens L1, an aperture STO, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an IR, and an imaging surface IMA.

[0069] The first lens L1 has a negative optical power. The object side surface S1 of the first lens L1 is concave, and the image side surface S2 is convex.

[0070] The second lens L2 has a positive optical power. The object side surface S4 of the second lens L2 is convex, and the image side surface S5 is convex.

[0071] The third lens L3 has a negative optical power. The object side surface S6 of the third lens L3 is convex, and the image side surface S7 is concave.

[0072] The fourth lens L4 has a positive optical power. The object side surface S8 of the fourth lens L4 is concave, and the image side surface S9 is convex.

[0073] The fifth lens L5 has a positive optical power. The object side surface S10 of the fifth lens L2 is convex, and the image side surface S11 is concave.

[0074] By adopting the above lens design, the lens has high image quality and low chromatic aberration, and at the same time, the optical system has a large field angle. The lens adopts an all-plastic design, which reduces costs and effectively reduces the weight of the lens. <00​​​​​​​​​​​​In addition, in some embodiments, the lens may also satisfy the following conditional formula:

[0080] -1 <R1 / R2<1.5;

[0081] -3 <R3 / R4<2;

[0082] 0 <R5 / R6<3;

[0083] -1 <R7 / R8<2;

[0084] Wherein, R1 is the radius of curvature of the object side of the first lens,

[0085] R2 is the curvature radius of the image side of the first lens,

[0086] R3 is the radius of curvature of the object side of the second lens,

[0087] R4 is the curvature radius of the image side of the second lens,

[0088] R5 is the radius of curvature of the object side of the third lens,

[0089] R6 is the curvature radius of the image side of the third lens,

[0090] R7 is the radius of curvature of the object side of the fourth lens,

[0091] R8 is the curvature radius of the image-side surface of the fourth lens.

[0092] The lens combination structure that satisfies the above curvature relationship can reasonably control the shape of each lens in the optical system, which helps to achieve a larger field of view and higher image quality.

[0093] In addition, in some embodiments, the lens may also satisfy the following conditional formula:

[0094] 0.85 <FNO / ENPD<1.8;

[0095] Where FNO is the aperture of the lens, and ENPD is the entrance pupil diameter of the lens. By satisfying the above relationship, the optical system has a larger aperture.

[0096] In addition, in some embodiments, the lens may also satisfy the following conditional formula:

[0097] 3.1 <TTL / tanHFOV<3.5;

[0098] Where TTL is the on-axis distance from the object-side surface of the first lens to the imaging plane, and HFOV is the half-angle of view of the lens's maximum field of view. Satisfying this relationship allows the optical system to have a larger field of view while maintaining a constant overall length, thereby controlling both the system's volume and field of view.

[0099] The first through fourth lenses are all aspherical. Due to the wide range of freedom offered by aspherical surfaces, their ability to deflect light and correct aberrations is significantly superior to spherical surfaces, improving lens resolution and correcting lens distortion. This also helps correct the angle of light exiting the lens, ensuring a better match with the sensor.

[0100] In addition, the lens can also meet the following conditions:

[0101] DFOV ≥ 110°,

[0102] Wherein, DFOV is the full field of view of the lens.

[0103] In addition, the lens can also meet the following conditions:

[0104] The lens satisfies the following conditional formula:

[0105] 50≤Vd1≤60,

[0106] 50≤Vd2≤60,

[0107] 20≤Vd3≤30,

[0108] 20≤Vd4≤61,

[0109] 20≤Vd5≤30,

[0110] Wherein, Vd1 is the Abbe number of the first lens,

[0111] Vd2 is the Abbe number of the second lens,

[0112] Vd3 is the Abbe number of the third lens,

[0113] Vd4 is the Abbe number of the fourth lens,

[0114] Vd5 is the Abbe number of the fifth lens.

[0115] Below, a high-quality diffractive-refractive hybrid lens is described in detail with reference to the accompanying drawings and examples.

[0116] Example 1

[0117] In this embodiment, lenses L1-L4 are all aspherical. Leveraging the wide range of freedom offered by aspherical surfaces, they offer superior correction capabilities for light deflection and aberration compared to spherical surfaces, further enhancing lens resolution and correcting lens distortion. This also helps correct the angle of light exiting the lens, ensuring a better match with the photosensitive element.

[0118] In the diffractive-refractive hybrid high-image-quality lens of this embodiment, by using a diffractive surface, the diffractive element has the characteristic of negative dispersion, which can correct the chromatic aberration of the optical system and thus improve the image quality of the optical system.

[0119] In this embodiment, the lens combination structure that satisfies the above curvature relationship can reasonably adjust the shape of each lens of the optical system, which helps to achieve a larger field of view angle and higher image quality.

[0120] Note: A negative aperture thickness does not represent the actual aperture thickness, but refers to the relative position, the position of the system aperture relative to the L2S1 surface.

[0121] Standard surface: When the surface radius is infinite and the cone coefficient is 0, it is a plane.

[0122] The lens design parameters of this embodiment can be shown in the following table.

[0123]

[0124] In the table above, the surface radius and thickness are in millimeters; the surface marked with "*" indicates an aspheric surface. The surface shape of the aspheric lens satisfies the following relationship:

[0125]

[0126] Wherein, parameter c is the curvature corresponding to the lens radius, y is the radial coordinate, the unit of the radial coordinate is the same as the unit of the lens length, and k is the coefficient of the conic quadratic curve; when the k coefficient is less than -1, the surface curve of the lens is a hyperbola, when the k coefficient is equal to -1, the surface curve of the lens is a parabola; when the k coefficient is between -1 and 0, the surface curve of the lens is an ellipse, when the k coefficient is equal to 0, the surface curve of the lens is a circle, and when the k coefficient is greater than 0, the surface curve of the lens is an oblate ellipse; a4, a6, a8, a 10 、a 12 、a 14 、a 16 These are the surface coefficients corresponding to the radial coordinates of the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders, respectively. The values ​​of the conic coefficient k are shown in the table above, and the other detailed aspheric parameters are shown in the table below.

[0127]

[0128] like Figures 2 to 5 As shown, Figure 2 The distortion curve of this embodiment is shown, where the horizontal axis is the system distortion value in percentage. As shown in the figure, the optical distortion of the system is less than 2%, so that the image deformation during shooting is extremely low and difficult for the human eye to detect, meeting the needs of photography. Figure 3This is the MTF curve of the system, with the horizontal axis representing frequency. As shown in the figure, at the high frequency band of 110, the MTF reaches a minimum of 55%. When shooting, the resolution of the image center and surrounding areas is high, and the overall clarity is high. Figure 4 This is the system's spot diagram, which uses diffuse spots to represent the system's aberrations. The smaller the diffuse spot, the smaller the system aberrations and the better the image quality. As shown in the figure, the system's maximum diffuse spot is 4.2 microns, indicating high image quality. Figure 5 The chromatic aberration curves of the system at different wavelengths are shown in the figure. As shown in the figure, the curves of all wavelengths are within the Airy disk, indicating that the imaging chromatic aberration of the system is small and not easy to detect.

[0129] Example 2

[0130] like Figure 6 , which is a lens cross-section and optical path diagram of the diffractive-refractive hybrid high image quality lens of this embodiment. The design parameters of a diffractive-refractive hybrid high image quality lens of this embodiment can be shown in the following table.

[0131]

[0132] Other detailed aspheric surface related parameters are shown in the following table.

[0133]

[0134]

[0135] like Figures 7 to 10 As shown, Figure 7 The distortion curve of this embodiment is shown. As shown in the figure, the optical distortion of the system is less than 1.9%, so that the image deformation during shooting is extremely low and difficult to be detected by the human eye. Figure 8 This is the MTF curve of the system. As shown in the figure, at the high frequency band of 110 frequencies, the MTF reaches a minimum of 52%. When shooting, the resolution of the image center and surrounding areas is high, and the overall clarity is high. Figure 9 This is the point diagram of the system. As shown in the figure, the maximum diffuse spot of the system is 2.9 microns, and the image quality is relatively high. Figure 10 The chromatic aberration curves of the system at different wavelengths are shown in the figure. As shown in the figure, the curves of all wavelengths are within the Airy disk, indicating that the imaging chromatic aberration of the system is small and not easy to detect.

[0136] Example 3

[0137] like Figure 11 , which is a lens cross-section and optical path diagram of the diffractive-refractive hybrid high image quality lens of this embodiment. The design parameters of the diffractive-refractive hybrid high image quality lens of this embodiment can be shown in the following table.

[0138]

[0139]

[0140] Other detailed aspheric surface related parameters are shown in the following table.

[0141]

[0142] like Figures 12 to 15 As shown, Figure 12 The distortion curve of this embodiment is shown. As shown in the figure, the optical distortion of the system is less than 1.8%, so that the image deformation during shooting is extremely low and difficult to be detected by the human eye, thus meeting the needs of photography. Figure 13 This is the MTF curve of the system. As shown in the figure, at the high frequency band of 110 frequencies, the MTF reaches a minimum of 50%. When shooting, the resolution of the image center and the surrounding areas is high, and the overall clarity is high. Figure 14 This is the point diagram of the system. As shown in the figure, the maximum diffuse spot of the system is 2.2 microns, and the image quality is relatively high. Figure 15 The chromatic aberration curves of the system at different wavelengths are shown in the figure. As shown in the figure, the curves of all wavelengths are within the Airy disk, indicating that the imaging chromatic aberration of the system is small and not easy to detect.

[0143] Within the technical scope disclosed by the present invention, any changes or substitutions that can be easily imagined should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A diffractive-refractive hybrid high-quality lens, characterized in that: From the object side to the image side along the optical axis, it includes: The first lens has a negative optical power, a concave object-side surface and a convex image-side surface; a second lens having positive optical power, a convex object-side surface and a convex image-side surface; The third lens has negative optical power, with a convex object-side surface and a concave image-side surface; The fourth lens element has positive optical power, a concave object-side surface and a convex image-side surface; The fifth lens element has positive optical power, a convex object-side surface and a concave image-side surface; The lens comprises at least one aspherical lens.

2. The high-quality diffractive-refractive hybrid lens according to claim 1, wherein: A stop is provided between the first lens and the second lens.

3. The diffractive-refractive hybrid high-quality lens according to claim 1, characterized in that: The fifth lens is a diffractive element, and both the object-side surface and the image-side surface are diffractive surfaces, and satisfy the following conditional formula: Wherein, M is the diffraction order, N is the diffraction surface polynomial order, Ai is the diffraction surface multi-term coefficient, ρ is the diffraction surface diameter, and the lens satisfies: M=1, N=16, -1 <A4<3、-1<A6<3、-1<A8<0、-3<A10<2、0<A12<2、-2<A14<2,-3<A16<3。 4. The high-quality diffractive-refractive hybrid lens according to claim 1, wherein: The lens satisfies the following conditional formula: -1 <R1 / R2<1.5; -3 <R3 / R4<2; 0 <R5 / R6<3; -1 <R7 / R8<2; Wherein, R1 is the radius of curvature of the objective side of the first lens, R2 is the curvature radius of the image side of the first lens, R3 is the radius of curvature of the second lens objective side, R4 is the curvature radius of the image side of the second lens, R5 is the radius of curvature of the object side of the third lens, R6 is the curvature radius of the image side of the third lens, R7 is the radius of curvature of the object side of the fourth lens, R8 is the curvature radius of the image-side surface of the fourth lens.

5. The high-quality diffractive-refractive hybrid lens according to claim 1, wherein: The lens satisfies the following conditional formula: 0.85 <FNO / ENPD<1.8; Wherein, FNO is the aperture of the lens, and ENPD is the entrance pupil diameter of the lens.

6. The high-quality diffractive-refractive hybrid lens according to claim 1, wherein: The lens satisfies the following conditional formula: 3.1 <TTL / tanHFOV<3.5; Wherein, TTL is the on-axis distance from the object side of the first lens to the imaging surface, HFOV is the half field of view angle of the maximum field of view of the lens.

7. The high-quality diffractive-refractive hybrid lens according to claim 1, wherein: The lens satisfies the following conditional formula: DFOV ≥ 110°, Wherein, DFOV is the full field of view of the lens.

8. The high-quality diffractive-refractive hybrid lens according to claim 1, wherein: The lens satisfies the following conditional formula: 50≤Vd1≤60, 50≤Vd2≤60, 20≤Vd3≤30, 20≤Vd4≤61, 20≤Vd5≤30, Wherein, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, Vd4 is the Abbe number of the fourth lens, Vd5 is the Abbe number of the fifth lens.

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