Optical lens

Abstract

The invention provides an optical lens comprising a first lens to a fourth lens. A circumferential area of the image side surface of the first lens is a concave surface, a circumferential area of the object side surface of the second lens is a convex surface, an optical axis area of the image side surface of the second lens is a concave surface, an optical axis area of the object side surface of the third lens is a convex surface, and an optical axis area of the object side surface of the fourth lens is a concave surface. A circumferential area of the image side surface of the fourth lens is a convex surface, the optical lens only comprises the four lenses, and the condition that (D21t42 + BFL) / G12 is smaller than or equal to 2.250 is met.

Description

Technical Field

[0001] This invention relates to an optical lens. Specifically, this invention is particularly directed to an optical lens primarily used for capturing images and videos, and applied in portable electronic products, such as mobile phones, headphones, cameras, tablet computers, personal digital assistants (PDAs), or head-mounted displays (AR, VR, MR). Background Technology

[0002] In recent years, optical lenses have continued to evolve, expanding their applications and diversifying their usage environments. They are no longer limited to capturing images and videos, but also include environmental monitoring, dashcam photography, virtual reality trackers (VRtrackers), and facial recognition. In addition to requiring lenses to be slim, lightweight, and compact, a wide field of view is also becoming increasingly important. Therefore, designing optical lenses that are scratch-resistant, slim, compact, have a wide field of view, and offer excellent optical quality to meet the demands of diverse usage environments and product aesthetics has become a challenge that needs to be addressed.

[0003] In addition, in portable electronic devices, the first lens, which is designed to complement the appearance, is often larger than other lenses due to factors such as surface aesthetics or mechanical strength requirements. In this case, adjusting the design of the remaining lenses to provide an optical imaging lens that balances the overall system's lightweight design with excellent image quality is a problem that the industry is currently trying to solve. Summary of the Invention

[0004] Therefore, various embodiments of the present invention propose a four-element optical lens that is wear-resistant, lightweight, compact, has a large field of view, excellent optical quality, and is technically feasible. The four-element optical lens of the present invention comprises a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side. Each of the first, second, third, and fourth lenses has an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through.

[0005] In one embodiment of the present invention, a circumferential region on the image side of the first lens is concave, a circumferential region on the object side of the second lens is convex, an optical axis region on the image side of the second lens is concave, an optical axis region on the object side of the third lens is convex, an optical axis region on the object side of the fourth lens is concave, and a circumferential region on the image side of the fourth lens is convex. The optical lens has only the above four lenses and satisfies the condition (D21t42+BFL) / G12≤2.250.

[0006] In one embodiment of the present invention, a circumferential region on the image side of the first lens is concave, a circumferential region on the object side of the second lens is convex, a circumferential region on the image side of the second lens is concave, an optical axis region on the object side of the third lens is convex, an optical axis region on the object side of the fourth lens is concave, and a circumferential region on the image side of the fourth lens is convex. The optical lens has only the above four lenses and satisfies the condition (D21t42+BFL) / G12≤2.250.

[0007] In one embodiment of the present invention, the first lens has a concave optical axis region on its image side, the second lens has a convex circular region on its object side, the third lens has a convex optical axis region on its object side, the fourth lens has a concave optical axis region on its object side, and the fourth lens has a convex circular region on its image side. The optical lens has only the above four lenses and satisfies the condition (ALT+BFL+ImgH) / G12≤2.450.

[0008] In one embodiment of the present invention, the first lens has a concave optical axis region on its image side, the second lens has a convex circular region on its object side, the third lens has a convex optical axis region on its object side, the fourth lens has a concave circular region on its object side, and the fourth lens has a convex circular region on its image side. The optical lens has only the above four lenses, and satisfies the condition (ALT+BFL+ImgH) / G12≤2.450.

[0009] In one embodiment of the present invention, a circumferential region on the object side of the second lens is convex, an optical axis region on the image side of the second lens is concave, an optical axis region on the object side of the third lens is convex, and the fourth lens has a positive refractive index and a circumferential region on the object side of the fourth lens is concave. The optical lens has only the above four lenses and satisfies the condition (ALT+BFL+ImgH) / G12≤2.450.

[0010] In one embodiment of the present invention, the optical axis region on the object side of the second lens is convex, the optical axis region on the image side of the second lens is concave, the optical axis region on the object side of the third lens is convex, the circumferential region on the object side of the fourth lens is concave, the optical axis region on the image side of the fourth lens is convex, and the circumferential region on the image side of the fourth lens is convex. The optical lens has only the above four lenses and satisfies the condition (ALT+EFL) / G12≤1.950.

[0011] In the optical lens of the present invention, each embodiment may also selectively satisfy the following conditions:

[0012] (AAG + BFL) / ImgH ≥ 3.500;

[0013] Fno * AAG / ALT ≥ 1.000;

[0014] ALT / (T1 + G12) ≤ 1.000;

[0015] TTL / ImgH ≥ 6.500;

[0016] G12 / BFL ≥ 0.750;

[0017] Fno * EFL / Tavg ≤ 6.500;

[0018] TTL / (AAG + BFL) ≤ 2.100;

[0019] Fno * (BFL + Tmin) / G12 ≤ 3.100;

[0020] G12 / (G23 + G34) ≥ 4.000;

[0021] Gmax / Tmin ≥ 4.000;

[0022] (T1 + G12) / (T3 + T4) ≥ 3.500;

[0023] (T1 + G12) / (Fno * Tmin) ≥ 4.400;

[0024] Gmax / Gmin ≥ 11.000;

[0025] (Tmax + Gmax / Tavg ≥ 4.200;

[0026] (Tavg + Gavg) / G34 ≥ 5.500;

[0027] TTL / AAG ≤ 4.000; and

[0028] TL / (Fno * Gmin) ≤ 1.500.

[0029] Where T1 is the thickness of the first lens on the optical axis; T3 is the thickness of the third lens on the optical axis; T4 is the thickness of the fourth lens on the optical axis. G12 is the air gap between the first and second lenses on the optical axis; G23 is the air gap between the second and third lenses on the optical axis; G34 is the air gap between the third and fourth lenses on the optical axis; Tavg is the average thickness of the four lenses on the optical axis from the first to the fourth lens; Tmax is the maximum thickness of the four lenses on the optical axis from the first to the fourth lens; Tmin is the minimum thickness of the four lenses on the optical axis from the first to the fourth lens; Gavg is the average thickness of the three air gaps on the optical axis from the first to the fourth lens; Gmax is the maximum thickness of the three air gaps on the optical axis from the first to the fourth lens; Gmin is the minimum thickness of the three air gaps on the optical axis from the first to the fourth lens. D21t42 is the distance on the optical axis from the object side of the second lens to the image side of the fourth lens.

[0030] ALT is the total thickness of the four lenses (first to fourth) on the optical axis; TL is the distance on the optical axis from the object side of the first lens to the image side of the fourth lens; TTL is the distance on the optical axis from the object side of the first lens to the imaging plane; BFL is the distance on the optical axis from the image side of the fourth lens to the imaging plane; AAG is the total air gap of the three lenses (first to fourth) on the optical axis; EFL is the effective focal length of the optical lens; ImgH is the image height of the optical lens; HFOV is the half angle of view of the optical lens; Fno is the aperture value of the optical lens. Attached Figure Description

[0031] Figure 1 A schematic diagram illustrating the method for determining the curvature shape of the optical lens of the present invention. Figure 1 ;

[0032] Figure 2 A schematic diagram illustrating the method for determining the curvature shape of the optical lens of the present invention. Figure 2 ;

[0033] Figure 3 A schematic diagram illustrating the method for determining the curvature shape of the optical lens of the present invention. Figure 3 ;

[0034] Figure 4 A schematic diagram illustrating the method for determining the curvature shape of the optical lens of the present invention. Figure 4 ;

[0035] Figure 5 A schematic diagram illustrating the method for determining the curvature shape of the optical lens of the present invention. Figure 5 ;

[0036] Figure 6 A schematic diagram illustrating a first embodiment of the optical lens of the present invention;

[0037] Figure 7 A diagram illustrating the parameters of the first embodiment of the optical lens of the present invention is provided; wherein, A represents longitudinal spherical aberration on the imaging plane; B represents field curvature aberration in the sagittal direction; C represents field curvature aberration in the meridional direction; and D represents distortion aberration.

[0038] Figure 8 A schematic diagram illustrating a second embodiment of the optical lens of the present invention;

[0039] Figure 9 A diagram illustrating the parameters of a second embodiment of the optical lens of the present invention is provided; wherein, A represents longitudinal spherical aberration on the imaging plane; B represents field curvature aberration in the sagittal direction; C represents field curvature aberration in the meridional direction; and D represents distortion aberration.

[0040] Figure 10 A schematic diagram illustrating a third embodiment of the optical lens of the present invention;

[0041] Figure 11 The diagram illustrates the parameters of the third embodiment of the optical lens of the present invention; wherein, A is the longitudinal spherical aberration on the imaging plane; B is the field curvature aberration in the sagittal direction; C is the field curvature aberration in the meridional direction; and D is the distortion aberration.

[0042] Figure 12 A schematic diagram illustrating a fourth embodiment of the optical lens of the present invention;

[0043] Figure 13 The diagram illustrates the parameters of the fourth embodiment of the optical lens of the present invention; wherein, A is the longitudinal spherical aberration on the imaging plane; B is the field curvature aberration in the sagittal direction; C is the field curvature aberration in the meridional direction; and D is the distortion aberration.

[0044] Figure 14 A schematic diagram illustrating a fifth embodiment of the optical lens of the present invention;

[0045] Figure 15 A diagram illustrating the parameters of a fifth embodiment of the optical lens of the present invention is provided; wherein, A represents longitudinal spherical aberration on the imaging plane; B represents field curvature aberration in the sagittal direction; C represents field curvature aberration in the meridional direction; and D represents distortion aberration.

[0046] Figure 16 A schematic diagram illustrating a sixth embodiment of the optical lens of the present invention;

[0047] Figure 17 A diagram illustrating the parameters of a sixth embodiment of the optical lens of the present invention is provided; wherein, A represents longitudinal spherical aberration on the imaging plane; B represents field curvature aberration in the sagittal direction; C represents field curvature aberration in the meridional direction; and D represents distortion aberration.

[0048] Figure 18 A schematic diagram illustrating a seventh embodiment of the optical lens of the present invention;

[0049] Figure 19 A diagram illustrating the parameters of a seventh embodiment of the optical lens of the present invention is provided; wherein, A represents longitudinal spherical aberration on the imaging plane; B represents field curvature aberration in the sagittal direction; C represents field curvature aberration in the meridional direction; and D represents distortion aberration.

[0050] Figure 20 A schematic diagram illustrating an eighth embodiment of the optical lens of the present invention;

[0051] Figure 21 The diagram illustrates the parameters of the optical lens of the present invention in an eighth embodiment; wherein, A is the longitudinal spherical aberration on the imaging plane; B is the field curvature aberration in the sagittal direction; C is the field curvature aberration in the meridional direction; and D is the distortion aberration.

[0052] Figure 22 This shows detailed optical data for the first embodiment;

[0053] Figure 23 This shows detailed aspherical data for the first embodiment;

[0054] Figure 24 This shows detailed optical data for the second embodiment;

[0055] Figure 25 This indicates detailed aspherical data for the second embodiment;

[0056] Figure 26 This describes the detailed optical data of the third embodiment;

[0057] Figure 27 This describes the detailed aspherical data of the third embodiment;

[0058] Figure 28 This shows the detailed optical data for the fourth embodiment;

[0059] Figure 29 This shows the detailed aspherical data of the fourth embodiment;

[0060] Figure 30 This shows detailed optical data for the fifth embodiment;

[0061] Figure 31 This shows the detailed aspherical data of the fifth embodiment;

[0062] Figure 32 This shows the detailed optical data for the sixth embodiment;

[0063] Figure 33 This shows the detailed aspherical data of the sixth embodiment;

[0064] Figure 34 This shows the detailed optical data of the seventh embodiment;

[0065] Figure 35 This shows the detailed aspherical data of the seventh embodiment;

[0066] Figure 36 This shows the detailed optical data of the eighth embodiment;

[0067] Figure 37 This shows the detailed aspherical data of the eighth embodiment;

[0068] Figure 38 One of the key parameters for each embodiment;

[0069] Figure 39 The second important parameter in each embodiment is indicated.

[0070] Figure label:

[0071] 1: Optical lens; 2: Aperture; 3: Filter; 4: Imaging plane; 5: Protective glass;

[0072] 11, 21, 31, 41: Side view of the object; 12, 22, 32, 42: Side view of the image;

[0073] 13, 16, 23, 26, 33, 36, 43, 46, Z1: Optical axis region;

[0074] 14, 17, 24, 27, 34, 37, 44, 47, Z2: Circular region;

[0075] 10: First lens; 20: Second lens; 30: Third lens; 40: Fourth lens;

[0076] 100, 200, 300, 400, 500: Lenses;

[0077] 130: Assembly section; 211, 212: Parallel rays; A1: Object side; A2: Image side;

[0078] I: Optical axis; CP: Center point; CP1: First center point; CP2: Second center point;

[0079] OB: Optical boundary; Lc: Principal ray; Lm: Marginal ray; TP1: First conversion point;

[0080] TP2: Second conversion point; Z3: Relay area; EL: Extension line; M, R: Intersection point. Detailed Implementation

[0081] The terms "optical axis region," "circumferential region," "concave surface," and "convex surface" used in this specification and the claims should be interpreted based on the definitions listed in this specification.

[0082] The optical system described in this specification includes at least one lens that receives imaging rays incident on the optical system from parallel to the optical axis to within a half-angle (HFOV) relative to the optical axis. The imaging rays pass through the optical system and form an image on the imaging plane. The statement "a lens has a positive (or negative) refractive index" means that the paraxial refractive index of the lens, calculated using Gaussian optics theory, is positive (or negative). The statement "the object side (or image side) of the lens" is defined as the specific range through which the imaging rays pass on the lens surface. The imaging rays include at least two types of rays: the chief ray (Lc) and the marginal ray (Lm) (e.g., ...). Figure 1 (As shown). The object side (or image side) of the lens can be divided into different regions depending on the location, including the optical axis region, the circumferential region, or one or more relay regions in some embodiments, which will be described in detail below.

[0083] Figure 1 This is a radial sectional view of lens 100. Two reference points are defined on the surface of lens 100: a center point and a transition point. The center point of the lens surface is the intersection of this surface and the optical axis I. For example... Figure 1 As illustrated, the first center point CP1 is located on the object-side surface 110 of lens 100, and the second center point CP2 is located on the image-side surface 120 of lens 100. A transition point is a point on the lens surface whose tangent is perpendicular to the optical axis I. The optical boundary OB of the lens surface is defined as the point where the outermost radially outermost edge ray Lm passing through the lens surface intersects the lens surface. All transition points are located between the optical axis I and the optical boundary OB of the lens surface. In addition, the surface of lens 100 may have no transition points or at least one transition point. If a single lens surface has multiple transition points, these transition points are named sequentially from the first transition point in the radially outward direction. For example, the first transition point TP1 (closest to the optical axis I), the second transition point TP2 (as shown in the example), and the third transition point TP2 (as shown in the example) are named sequentially from the first transition point in the radially outward direction. Figure 4 (as shown) and the Nth conversion point (farthest from optical axis I).

[0084] When the lens surface has at least one transition point, the region from the center point to the first transition point TP1 is defined as the optical axis region, which includes the center point. The region radially outward from the transition point farthest from optical axis I (the Nth transition point) to the optical boundary OB is defined as the circumferential region. In some embodiments, a relay region may be included between the optical axis region and the circumferential region; the number of relay regions depends on the number of transition points. When the lens surface does not have a transition point, 0% to 50% of the distance from optical axis I to the optical boundary OB of the lens surface is defined as the optical axis region, and 50% to 100% of the distance from optical axis I to the optical boundary OB of the lens surface is defined as the circumferential region.

[0085] When a ray parallel to optical axis I passes through a region, if the ray bends towards optical axis I and the intersection point with optical axis I is located on the image side A2 of the lens, then that region is a convex surface. When a ray parallel to optical axis I passes through a region, if the extension of the ray intersects optical axis I at the object side A1 of the lens, then that region is a concave surface.

[0086] In addition, see Figure 1 The lens 100 may also include an assembly portion 130 extending radially outward from the optical boundary OB. The assembly portion 130 is generally used for assembling the lens 100 to a corresponding element (not shown) in an optical system. Imaging rays do not reach the assembly portion 130. The structure and shape of the assembly portion 130 are merely illustrative examples of the invention and are not intended to limit the scope of the invention. The assembly portion 130 of the lens discussed below may be partially or entirely omitted in the drawings.

[0087] See Figure 2 Define the region between the center point CP and the first conversion point TP1 as the optical axis region Z1. Define the region between the first conversion point TP1 and the optical boundary OB of the lens surface as the circumferential region Z2. For example... Figure 2 As shown, parallel ray 211 intersects optical axis I at the image side A2 of lens 200 after passing through optical axis region Z1. That is, the focal point of parallel ray 211 passing through optical axis region Z1 is located at point R on the image side A2 of lens 200. Since the ray intersects optical axis I at the image side A2 of lens 200, optical axis region Z1 is convex. Conversely, parallel ray 212 diverges after passing through circular region Z2. Figure 2 As shown, the extension EL of parallel ray 212 after passing through the circular region Z2 intersects the optical axis I at the object side A1 of the lens 200. That is, the focal point of parallel ray 212 after passing through the circular region Z2 is located at point M on the object side A1 of the lens 200. Since the extension EL of the ray intersects the optical axis I at the object side A1 of the lens 200, the circular region Z2 is concave. Figure 2 In the lens 200 shown, the first conversion point TP1 is the boundary between the optical axis region and the circumferential region, that is, the first conversion point TP1 is the boundary point between the convex surface and the concave surface.

[0088] On the other hand, the convexity / concavity of the optical axis region can also be determined using the method commonly used by those knowledgeable in the field: judging the convexity / concavity of the lens's optical axis region by the sign of the paraxial radius of curvature (R-value). The R-value is commonly used in optical design software, such as Zemax or CodeV. It is also frequently found in lens data sheets within optical design software. For the object-side, a positive R-value indicates a convex optical axis region, while a negative R-value indicates a concave optical axis region. Conversely, for the image-side, a positive R-value indicates a concave optical axis region, while a negative R-value indicates a convex optical axis region. This method yields results consistent with the aforementioned method using the intersection of a ray / ray extension with the optical axis, where the focal point of a ray parallel to the optical axis is located on either the object-side or image-side of the lens to determine the convexity / concavity. The terms "a region is convex (or concave)," "a region is convex (or concave)," or "a convex (or concave) region" used in this specification may be used interchangeably.

[0089] Figures 3 to 5 Examples of determining the surface shape and boundaries of the lens region in various situations are provided, including the aforementioned optical axis region, circumferential region, and relay region.

[0090] Figure 3 This is a radial sectional view of lens 300. See also... Figure 3 The image-side surface 320 of lens 300 has only one transition point TP1 within the optical boundary OB. The optical axis region Z1 and circumferential region Z2 of the image-side surface 320 of lens 300 are as follows... Figure 3 As shown. The R value of the side surface 320 of this image is positive (i.e., R>0), therefore, the optical axis region Z1 is concave.

[0091] Generally, the surface shape of each region bounded by a transition point will be opposite to that of its adjacent regions. Therefore, the transition point can be used to define the change in surface shape, i.e., from the transition point, a surface changes from concave to convex or from convex to concave. Figure 3 In the middle, since the optical axis region Z1 is concave and its shape changes at the transition point TP1, the circumferential region Z2 is convex.

[0092] Figure 4 This is a radial sectional view of lens 400. See also... Figure 4 The object-side surface 410 of lens 400 has a first conversion point TP1 and a second conversion point TP2. The area between the optical axis I and the first conversion point TP1 is defined as the optical axis region Z1 of the object-side surface 410. The R value of this object-side surface 410 is positive (i.e., R>0), therefore, the optical axis region Z1 is a convex surface.

[0093] The area between the second conversion point TP2 and the optical boundary OB of the object-side surface 410 of the lens 400 is defined as a circumferential region Z2, which is also a convex surface. Furthermore, the area between the first conversion point TP1 and the second conversion point TP2 is defined as a relay region Z3, which is also a concave surface. See again. Figure 4 The object-side surface 410, radially outward from the optical axis I, sequentially includes the optical axis region Z1 between the optical axis I and the first conversion point TP1, the relay region Z3 located between the first conversion point TP1 and the second conversion point TP2, and the circumferential region Z2 between the second conversion point TP2 and the optical boundary OB of the object-side surface 410 of the lens 400. Since the optical axis region Z1 is convex, and its surface shape changes to concave from the first conversion point TP1, the relay region Z3 is concave. Furthermore, its surface shape changes to convex again from the second conversion point TP2, so the circumferential region Z2 is convex.

[0094] Figure 5 This is a radial sectional view of lens 500. The object-side surface 510 of lens 500 has no transition point. For a lens surface without a transition point, such as the object-side surface 510 of lens 500, the optical axis region is defined as 0% to 50% of the distance from the optical axis I to the optical boundary OB of the lens surface, and the circumferential region is defined as 50% to 100% of the distance from the optical axis I to the optical boundary OB of the lens surface. See also Figure 5 The lens 500 shown defines the optical axis region Z1 of the object-side surface 510 as 50% of the distance from the optical axis I to the optical boundary OB of the lens 500 surface. The R value of this object-side surface 510 is positive (i.e., R > 0), therefore, the optical axis region Z1 is convex. Since the object-side surface 510 of the lens 500 has no transition point, the circumferential region Z2 of the object-side surface 510 is also convex. The lens 500 may further have an assembly portion (not shown) extending radially outward from the circumferential region Z2.

[0095] like Figure 6 As shown, the optical lens 1 of the present invention, from the object side A1 where the object (not shown) is placed to the image side A2 where the image is formed, along the optical axis I, is mainly composed of four lenses, sequentially including a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and an image plane 4. Generally speaking, the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 can all be made of glass or transparent plastic, but the present invention is not limited thereto. Each lens has an appropriate refractive index. In the optical lens 1 of the present invention, there are only four lenses with refractive indices: the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40. The optical axis I is the optical axis of the entire optical lens 1, so the optical axis of each lens is the same as the optical axis of the optical lens 1.

[0096] Furthermore, this optical lens 1 also includes an aperture stop 2, which is set in an appropriate position. Figure 6 In this invention, aperture 2 is positioned on the side of the third lens 30 facing the object side A1, that is, between the second lens 20 and the third lens 30. When light emitted from the object to be photographed (not shown) located on the object side A1 enters the optical lens 1 of this invention, it passes sequentially through the first lens 10, the second lens 20, aperture 2, the third lens 30, the fourth lens 40, and the filter 3, and is then focused on the imaging surface 4 on the image side A2 to form a clear image. In various embodiments of this invention, the filter 3 is positioned between the fourth lens 40 and the imaging surface 4. It can be a filter with various suitable functions, such as an infrared cut-off filter, which is used to prevent infrared rays in the imaging light from being transmitted to the imaging surface 4 and affecting the image quality.

[0097] In addition, the present invention also includes a protective glass 5 disposed between the filter 3 and the imaging surface 4. The function of the protective glass 5 is to protect the structure of the optical imaging lens 1 from damage caused by impacts or other factors. However, in some embodiments, the protective glass 5 may be omitted, that is, a protective glass 5 may not be formed between the filter 3 and the imaging surface 4. Such a variation is also within the scope of the present invention.

[0098] Each lens in the optical lens 1 of the present invention has an object-side surface facing the object side A1 and through which imaging light passes, and an image-side surface facing the image side A2 and through which imaging light passes. Furthermore, each lens in the optical lens 1 of the present invention also has an optical axis region and a circumferential region. For example, the first lens 10 has an object-side surface 11 and an image-side surface 12; the second lens 20 has an object-side surface 21 and an image-side surface 22; the third lens 30 has an object-side surface 31 and an image-side surface 32; and the fourth lens 40 has an object-side surface 41 and an image-side surface 42. Each object-side surface and each image-side surface also has an optical axis region and a circumferential region.

[0099] Each lens in the optical lens 1 of the present invention also has a thickness T located on the optical axis I. For example, the first lens 10 has a first lens thickness T1, the second lens 20 has a second lens thickness T2, the third lens 30 has a third lens thickness T3, and the fourth lens 40 has a fourth lens thickness T4. ALT is the sum of the thicknesses of the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 on the optical axis I in the optical lens 1 of the present invention. That is, ALT = T1 + T2 + T3 + T4; Tmax is the maximum value of the four lens thicknesses of the first lens 10 to the fourth lens 40 on the optical axis I, that is, the maximum value of T1, T2, T3, and T4. Tmin is the minimum value of the four lens thicknesses of the first lens 10 to the fourth lens 40 on the optical axis I, that is, the minimum value of T1, T2, T3, and T4. Tavg is the average value of the four lens thicknesses of the first lens 10 to the fourth lens 40 on the optical axis I, the average value of T1, T2, T3, and T4.

[0100] Furthermore, in the optical lens 1 of this invention, each lens has an air gap located on the optical axis I. For example, the air gap between the first lens 10 and the second lens 20 is called G12, the air gap between the second lens 20 and the third lens 30 is called G23, and the air gap between the third lens 30 and the fourth lens 40 is called G34. Gmax is the maximum value of the three air gaps between the first lens 10 and the fourth lens 40 on the optical axis I, i.e., the maximum value of G12, G23, and G34. Gmin is the minimum value of the three air gaps between the first lens 10 and the fourth lens 40 on the optical axis I, i.e., the minimum value of G12, G23, and G34. Gavg is the average value of the three air gaps between the first lens 10 and the fourth lens 40 on the optical axis I, i.e., the average value of G12, G23, and G34. The sum of the distances between the three air gaps between the first lens 10 and the fourth lens 40 on the optical axis I is called AAG, that is, AAG = G12 + G23 + G34.

[0101] The distance on the optical axis I from the object-side surface 11 of the first lens 10 to the image-side surface 4 is the system length TTL of the optical lens 1. The effective focal length of the optical lens 1 is EFL, and the distance on the optical axis I from the object-side surface 11 of the first lens 10 to the image-side surface 42 of the fourth lens 40 is TL. HFOV is the half-field of view of the optical lens 1, that is, half of the maximum field of view, ImgH (image height) is the image height of the optical lens 1, and Fno is the aperture value of the optical lens 1.

[0102] When filter 3 is positioned between fourth lens 40 and imaging surface 4, G4F represents the air gap between fourth lens 40 and filter 3 on optical axis I, TF represents the thickness of filter 3 on optical axis I, GFP represents the air gap between filter 3 and imaging surface 4 on optical axis I, and BFL is the back focal length of optical lens 1, which is the distance between the image side surface 42 of fourth lens 40 and imaging surface 4 on optical axis I, i.e., BFL = G4F + TF + GFP.

[0103] Furthermore, D21t42 is defined as the distance on the optical axis I from the object side 21 of the second lens 20 to the image side 42 of the fourth lens 40, i.e., the sum of T2, G23, T3, G34, and T4. f1 is the focal length of the first lens 10; f2 is the focal length of the second lens 20; f3 is the focal length of the third lens 30; f4 is the focal length of the fourth lens 40; n1 is the nd refractive index of the first lens 10; n2 is the nd refractive index of the second lens 20; n3 is the nd refractive index of the third lens 30; n4 is the nd refractive index of the fourth lens 40; V1 is the Vd Abbe number of the first lens 10; V2 is the Vd Abbe number of the second lens 20; V3 is the Vd Abbe number of the third lens 30; V4 is the Vd Abbe number of the fourth lens 40.

[0104] It is worth noting that the material parameters of the lenses disclosed in the optical data sheets of the various embodiments of the present invention are in the international glass code format of nd refractive index and Vd Abbe number, so that those skilled in the art can know the specific material implementation. Here, nd is the refractive index of the material at the d-helium yellow line of 587.56 nm, and Vd is calculated using the refractive index of the material at the d, F, and C wavelengths of the Fraunhofer spectrum. The focal length values ​​disclosed in the optical data sheets of the embodiments are calculated using the refractive index of the band in which the optical system is implemented. Since the primary wavelength of the embodiments of the present invention is 940 nm, the focal length values ​​of the present invention are calculated using the refractive index of the material at 940 nm.

[0105] First Embodiment

[0106] Please see Figure 6 This example illustrates a first embodiment of the optical lens 1 of the present invention. For the longitudinal spherical aberration on the imaging plane 4 in the first embodiment, please refer to... Figure 7 For the field curvature aberrations in part A and the sagittal direction, please refer to [reference needed]. Figure 7 For part B and the field curvature aberration in the tangential direction, please refer to [reference needed]. Figure 7 For Part C and distortion aberration, please refer to [reference needed]. Figure 7Part D. In all embodiments, the Y-axis of each spherical aberration map represents the field of view, and its highest point is 1.0. In the embodiments, the Y-axis of each aberration map and distortion map represents the image height. The image height (ImgH) of the first embodiment is 0.440 mm.

[0107] The optical lens 1 of the first embodiment mainly consists of four lenses with refractive indices, an aperture 2, and an imaging plane 4. The aperture 2 of the first embodiment is located on the side of the third lens 30 facing the object side A1.

[0108] The first lens 10 has a positive refractive index. The optical axis region 13 of the object-side surface 11 of the first lens 10 is convex, and its circumferential region 14 is also convex. The optical axis region 16 of the image-side surface 12 of the first lens 10 is concave, and its circumferential region 17 is also concave. Both the object-side surface 11 and the image-side surface 12 of the first lens 10 are spherical, but this is not a limitation.

[0109] The second lens 20 has a positive refractive index. The optical axis region 23 and its circumferential region 24 of the object-side surface 21 of the second lens 20 are convex, and the optical axis region 26 and its circumferential region 27 of the image-side surface 22 of the second lens 20 are concave. Both the object-side surface 21 and the image-side surface 22 of the second lens 20 are aspherical, but this is not a limitation.

[0110] The third lens 30 has a positive refractive index. The optical axis region 33 of the object side 31 of the third lens 30 is convex and its circumferential region 34 is concave. The optical axis region 36 of the image side 32 of the third lens 30 is convex and its circumferential region 37 is convex. Both the object side 31 and the image side 32 of the third lens 30 are aspherical, but this is not a limitation.

[0111] The fourth lens 40 has a negative refractive index. The optical axis region 43 of the object-side surface 41 of the fourth lens 40 is concave, and its circumferential region 44 is also concave. The optical axis region 46 of the image-side surface 42 of the fourth lens 40 is convex, and its circumferential region 47 is also convex. Both the object-side surface 41 and the image-side surface 42 of the fourth lens 40 are aspherical, but this is not a limitation.

[0112] In the optical lens 1 of this invention, except for the object-side surface 11 and image-side surface 12 of the first lens 10, which are spherical, all six curved surfaces from the second lens 20 to the fourth lens 40—the object-side surfaces 21, 31, and 41 and the image-side surfaces 22, 32, and 42—are aspherical, but this is not a limitation. If they are aspherical, these aspherical surfaces are defined by the following formula:

[0113]

[0114] in:

[0115] Y represents the perpendicular distance between a point on the aspherical surface and the optical axis I;

[0116] Z represents the depth of the aspherical surface (the perpendicular distance between a point on the aspherical surface that is Y away from the optical axis I and the tangent plane that is tangent to the vertex on the optical axis I of the aspherical surface).

[0117] R represents the radius of curvature of the lens surface near the optical axis I;

[0118] K is the conic constant;

[0119] a i Let a be the i-th order aspherical coefficient, where the a2 coefficient in each embodiment is 0.

[0120] The optical data of the optical lens system in the first embodiment are as follows: Figure 22 As shown, the aspherical data is as follows Figure 23 As shown. In the optical lens system of the following embodiments, the overall optical lens has an aperture value (f-number) of Fno, an effective focal length (EFL), and a half field of view (HFOV) that is half of the maximum field of view of the overall optical lens. The image height, radius of curvature, thickness, and focal length of the optical lens are all in millimeters (mm). In this embodiment, EFL = 0.853 mm; HFOV = 32.356 degrees; TTL = 3.142 mm; Fno = 2.136; image height = 0.440 mm. Longitudinal spherical aberration = ±0.0185 mm; sagittal aberration = ±19 micrometers (μm); meridional aberration = ±19 micrometers; distortion aberration = ±23%.

[0121] Second Embodiment

[0122] Please see Figure 8 The following illustrates a second embodiment of the optical lens 1 of the present invention. Note that, starting with the second embodiment, for the sake of simplicity and clarity in the drawings, only the optical axis regions and circumferential regions of each lens with different surface types from the first embodiment are specifically marked on the drawings. The optical axis regions and circumferential regions of the same surface types as the lenses in the first embodiment, such as concave or convex surfaces, are not separately marked. For the longitudinal spherical aberration on the imaging plane 4 in the second embodiment, please refer to... Figure 9 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 9 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 9 For part C and distortion aberrations, please refer to [reference needed]. Figure 9Part D. The design of the second embodiment is similar to that of the first embodiment, except that the only differences are in related parameters such as lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length. In addition, in this embodiment, the second lens 20 has a negative refractive index, the circumferential region 34 of the object side 31 of the third lens 30 is convex, and the fourth lens 40 has a positive refractive index.

[0123] Detailed optical data for the second embodiment are as follows: Figure 24 As shown, the aspherical data is as follows Figure 25 As shown. In this embodiment, EFL = 0.713 mm; HFOV = 37.441 degrees; TTL = 2.908 mm; Fno = 2.138; image height = 0.440 mm. Longitudinal spherical aberration = ±0.0028 mm; sagittal aberration = ±13 μm; meridional aberration = ±7.3 μm; distortion aberration = ±21.5%. In particular: 1. The system length of this embodiment is less than that of the first embodiment; 2. The half-angle of view of this embodiment is greater than that of the first embodiment; 3. The longitudinal spherical aberration of this embodiment is better than that of the first embodiment; 4. The sagittal aberration of this embodiment is better than that of the first embodiment; 5. The meridional aberration of this embodiment is better than that of the first embodiment; 6. The distortion aberration of this embodiment is better than that of the first embodiment.

[0124] Third Embodiment

[0125] Please see Figure 10 This illustrates a third embodiment of the optical lens 1 of the present invention. For the longitudinal spherical aberration on the imaging plane 4 in the third embodiment, please refer to... Figure 11 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 11 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 11 For part C and distortion aberrations, please refer to [reference needed]. Figure 11 Part D. The design of the third embodiment is similar to that of the first embodiment, except that the only differences are in related parameters such as lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length. In addition, in this embodiment, the second lens 20 has a negative refractive index, the circumferential region 34 of the object side 31 of the third lens 30 is convex, and the fourth lens 40 has a positive refractive index.

[0126] Detailed optical data for the third embodiment are as follows: Figure 26 As shown, the aspherical data is as follows Figure 27As shown, in this embodiment, EFL = 0.642 mm; HFOV = 39.959 degrees; TTL = 4.569 mm; Fno = 2.174; image height = 0.440 mm. Longitudinal spherical aberration = ±0.0029 mm; sagittal aberration = ±11 μm; meridional aberration = ±6.6 μm; distortion aberration = ±20%. Specifically: 1. The half-angle of view in this embodiment is greater than that in the first embodiment; 2. The longitudinal spherical aberration in this embodiment is better than that in the first embodiment; 3. The sagittal aberration in this embodiment is better than that in the first embodiment; 4. The meridional aberration in this embodiment is better than that in the first embodiment; 5. The distortion aberration in this embodiment is better than that in the first embodiment.

[0127] Fourth embodiment

[0128] Please see Figure 12 The fourth embodiment of the optical lens 1 of the present invention is illustrated below. For the longitudinal spherical aberration on the imaging plane 4 in the fourth embodiment, please refer to... Figure 13 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 13 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 13 For part C and distortion aberrations, please refer to [reference needed]. Figure 13 Part D. The design of the fourth embodiment is similar to that of the first embodiment, except that the only differences are in related parameters such as lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length. In addition, in this embodiment, the optical axis region 13 of the object side 11 of the first lens 10 is concave and its circumferential region 14 is concave; the optical axis region 16 of the image side 12 of the first lens 10 is convex and its circumferential region 17 is convex; the second lens 20 has a negative refractive index; and the circumferential region 34 of the object side 31 of the third lens 30 is convex.

[0129] Detailed optical data for the fourth embodiment are as follows: Figure 28 As shown, the aspherical data is as follows Figure 29 As shown. In this embodiment, EFL = 0.651 mm; HFOV = 40.165 degrees; TTL = 4.535 mm; Fno = 2.201; image height = 0.440 mm. Longitudinal spherical aberration = ±0.0052; sagittal aberration = ±10 μm; meridional aberration = ±12.5 μm; distortion aberration = ±21%. In particular: 1. The half-angle of view in this embodiment is greater than that in the first embodiment; 2. The longitudinal spherical aberration in this embodiment is better than that in the first embodiment; 3. The sagittal aberration in this embodiment is better than that in the first embodiment; 4. The meridional aberration in this embodiment is better than that in the first embodiment; 5. The distortion aberration in this embodiment is better than that in the first embodiment.

[0130] Fifth Embodiment

[0131] Please see Figure 14 This illustrates a fifth embodiment of the optical lens 1 of the present invention. For the longitudinal spherical aberration on the imaging plane 4 in the fifth embodiment, please refer to... Figure 15 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 15 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 15 For part C and distortion aberrations, please refer to [reference needed]. Figure 15 Part D. The design of the fifth embodiment is similar to that of the first embodiment, except that the only differences are in related parameters such as lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length. In addition, in this embodiment, the first lens 10 has a negative refractive index, the second lens 20 has a negative refractive index, the circumferential region 34 of the object side 31 of the third lens 30 is convex, and the fourth lens 40 has a positive refractive index.

[0132] Detailed optical data for the fifth embodiment are as follows: Figure 30 As shown, the aspherical data is as follows Figure 31 As shown, in this embodiment, EFL = 0.671 mm; HFOV = 38.159 degrees; TTL = 3.028 mm; Fno = 2.153; image height = 0.440 mm. Longitudinal spherical aberration = ±0.0029 mm; sagittal aberration = ±12.5 μm; meridional aberration = ±8.75 μm; distortion aberration = ±18%. Specifically: 1. The system length of this embodiment is less than that of the first embodiment; 2. The half-angle of view of this embodiment is greater than that of the first embodiment; 3. The longitudinal spherical aberration of this embodiment is better than that of the first embodiment; 4. The sagittal aberration of this embodiment is better than that of the first embodiment; 5. The meridional aberration of this embodiment is better than that of the first embodiment; 6. The distortion aberration of this embodiment is better than that of the first embodiment.

[0133] Sixth Embodiment

[0134] Please see Figure 16 The sixth embodiment of the optical lens 1 of the present invention is illustrated below. For the longitudinal spherical aberration on the imaging plane 4 in the sixth embodiment, please refer to... Figure 17 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 17 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 17 For part C and distortion aberrations, please refer to [reference needed]. Figure 17 Part D. The design of the sixth embodiment is similar to that of the first embodiment, except that the only differences are in related parameters such as lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length. In addition, in this embodiment, the first lens 10 has a negative refractive index, and the optical axis region 13 of the object side 11 of the first lens 10 is concave and its circumferential region 14 is concave.

[0135] Detailed optical data for the sixth embodiment are as follows: Figure 32 As shown, the aspherical data is as follows Figure 33 As shown, in this embodiment, EFL = 0.741 mm; HFOV = 39.905 degrees; TTL = 4.095 mm; Fno = 2.188; image height = 0.440 mm. Longitudinal spherical aberration = ±0.0086 mm; sagittal aberration = ±10 μm; meridional aberration = ±25 μm; distortion aberration = ±31%. Specifically: 1. The half-angle of view in this embodiment is greater than that in the first embodiment; 2. The longitudinal spherical aberration in this embodiment is better than that in the first embodiment; 3. The sagittal aberration in this embodiment is better than that in the first embodiment.

[0136] Seventh Embodiment

[0137] Please see Figure 18 The seventh embodiment of the optical lens 1 of the present invention is illustrated below. For the longitudinal spherical aberration on the imaging plane 4 in the seventh embodiment, please refer to... Figure 19 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 19 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 19 For part C and distortion aberrations, please refer to [reference needed]. Figure 19 Part D. The design of the seventh embodiment is similar to that of the first embodiment, except that the lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length are different. In addition, in this embodiment, the first lens 10 has a negative refractive index, the optical axis region 13 of the object side 11 of the first lens 10 is concave and its circumferential region 14 is concave, the third lens 30 has a negative refractive index, the optical axis region 36 of the image side 32 of the third lens 30 is concave and its circumferential region 37 is concave, and the fourth lens 40 has a positive refractive index.

[0138] Detailed optical data for the seventh embodiment are as follows: Figure 34 As shown, the aspherical data is as follows Figure 35 As shown, in this embodiment, EFL = 0.712 mm; HFOV = 35.465 degrees; TTL = 3.958 mm; Fno = 2.201; image height = 0.440 mm. Longitudinal spherical aberration = ±0.012 mm; sagittal aberration = ±0.05 mm; meridional aberration = ±0.05 mm; distortion aberration = ±13.5%. 1. The half-angle of view in this embodiment is greater than that in the first embodiment; 2. The longitudinal spherical aberration in this embodiment is better than that in the first embodiment; 3. The distortion aberration in this embodiment is better than that in the first embodiment.

[0139] Eighth embodiment

[0140] Please see Figure 20 The eighth embodiment of the optical lens 1 of the present invention is illustrated below. For the longitudinal spherical aberration on the imaging plane 4 in the eighth embodiment, please refer to... Figure 21 For part A and the field curvature aberration in the sagittal direction, please refer to [reference needed]. Figure 21 For Part B and the field curvature aberrations in the meridional direction, please refer to [reference needed]. Figure 21 For part C and distortion aberrations, please refer to [reference needed]. Figure 21 Part D. The design of the eighth embodiment is similar to that of the first embodiment, except that the lens refractive index, lens radius of curvature, lens thickness, lens aspherical coefficient, or back focal length are different. In addition, in this embodiment, the optical axis region 13 of the object side 11 of the first lens 10 is concave and its circumferential region 14 is concave; the optical axis region 16 of the image side 12 of the first lens 10 is convex and its circumferential region 17 is convex; the second lens 20 has a negative refractive index; and the fourth lens 40 has a positive refractive index.

[0141] Detailed optical data for the eighth embodiment are as follows: Figure 36 As shown, the aspherical data is as follows Figure 37 As shown, in this embodiment, EFL = 0.630 mm; HFOV = 39.975 degrees; TTL = 3.457 mm; Fno = 2.154; image height = 0.440 mm. Longitudinal spherical aberration = ±0.005 mm; sagittal aberration = ±10.4 μm; meridional aberration = ±13 μm; distortion aberration = ±18%. Specifically: 1. The half-angle of view in this embodiment is greater than that in the first embodiment; 2. The longitudinal spherical aberration in this embodiment is better than that in the first embodiment; 3. The sagittal aberration in this embodiment is better than that in the first embodiment; 4. The meridional aberration in this embodiment is better than that in the first embodiment; 5. The distortion aberration in this embodiment is better than that in the first embodiment.

[0142] In addition, the key parameters of each embodiment are summarized in Figure 38 and Figure 39 middle.

[0143] Various embodiments of the present invention provide a lightweight, compact, and technically feasible four-element optical lens that maintains good image quality, possesses excellent optical performance, and exhibits good optical characteristics. For example, designs that satisfy the following lens surface shape and refractive index can effectively optimize the optical quality of the lens and achieve the corresponding effects:

[0144] 1. In the optical imaging lens of the present invention, by adjusting the relationship between the distance (D21t42) between the object side 21 of the second lens 20 and the image side 42 of the fourth lens 40, the back focal length (BFL), and the air gap (G12) between the first lens 10 and the second lens 20, and satisfying the ratio constraint (D21t42+BFL) / G12≤2.250, the first lens 10, which meets the appearance requirements, can be adapted to the other lenses to achieve the purpose of reducing size, while simultaneously possessing better imaging quality. If the optical axis region 26 of the image side 22 of the second lens 20 is concave and the object side of the third lens 30 is concave... The optical axis region 33 of surface 31 is convex, and the optical axis region 43 of the object side surface 41 of the fourth lens 40 is concave. These conditions can correct the aberrations in the central field of view of the imaging surface. In addition, the surface shape of the circumferential region of a specific lens, such as the circumferential region 17 of the image side surface 12 of the first lens 10 being concave, the circumferential region 24 of the object side surface 21 of the second lens 20 being convex, and the circumferential region 47 of the image side surface 42 of the fourth lens 40 being convex, can further correct the distortion of the edge field of view. The preferred range of (D21t42+BFL) / G12 is 0.800≤(D21t42+BFL) / G12≤2.250.

[0145] 2. In the optical imaging lens of the present invention, by adjusting the relationship between the distance (D21t42) from the object side 21 of the second lens 20 to the image side 42 of the fourth lens 40, the back focal length (BFL), and the air gap (G12) between the first lens 10 and the second lens 20, and satisfying the ratio constraint (D21t42+BFL) / G12≤2.250, the first lens 10, which meets the appearance requirements, can be adapted to the other lenses to achieve the purpose of reducing size, while simultaneously possessing better imaging quality. If the optical axis region 33 of the object side 31 of the third lens 30 is convex, and the object side of the fourth lens 40 is... The optical axis region 43 of surface 41 is concave, which can correct the aberration of the central field of view of the imaging surface. In addition, the surface shape of the circumferential region of a specific lens, such as the circumferential region 17 of the image side 12 of the first lens 10 being concave, the circumferential region 24 of the object side 21 of the second lens 20 being convex, the circumferential region 27 of the image side 22 of the second lens 20 being concave, and the circumferential region 47 of the image side 42 of the fourth lens 40 being convex, can further correct the distortion of the edge field of view. The preferred range of (D21t42+BFL) / G12 is 0.800≤(D21t42+BFL) / G12≤2.250.

[0146] 3. In the optical imaging lens of the present invention, by adjusting the proportional relationship between the total thickness (ALT), back focal length (BFL), and image height (ImgH) of each lens and the air gap (G12) between the first lens 10 and the second lens 20, and satisfying the proportional constraint (ALT+BFL+ImgH) / G12≤2.450, the first lens 10, which meets the appearance requirements, can be adapted to the other lenses to achieve the purpose of reducing size, while simultaneously possessing better imaging quality. If the optical axis region 16 of the image side surface 12 of the first lens 10 is concave and the optical axis region of the image side surface 22 of the second lens 20 is concave... Conditions such as 26 being concave, the optical axis region 33 of the object side 31 of the third lens 30 being convex, and the optical axis region 43 of the object side 41 of the fourth lens 40 being concave can correct the aberration of the central field of view of the imaging plane. In addition, the surface shape of the circumferential region of a specific lens, such as the circumferential region 24 of the object side 21 of the second lens 20 being convex and the circumferential region 47 of the image side 42 of the fourth lens 40 being convex, can further correct the distortion of the edge field of view. The preferred range of (ALT+BFL+ImgH) / G12 is 1.300≤(ALT+BFL+ImgH) / G12≤2.450.

[0147] 4. In the optical imaging lens of the present invention, by adjusting the proportional relationship between the total thickness (ALT), back focal length (BFL), and image height (ImgH) of each lens and the air gap (G12) between the first lens 10 and the second lens 20, and satisfying the proportional constraint (ALT+BFL+ImgH) / G12≤2.450, the first lens, which meets the appearance requirements, can be adapted to the other lenses, achieving the purpose of reducing size while simultaneously possessing better imaging quality. If the optical axis region 16 of the image side 12 of the first lens 10 is concave, and the optical axis region of the image side 22 of the second lens 20 is... Domain 26 is concave, and the optical axis region 33 of the object side surface 31 of the third lens 30 is convex, which can correct the aberration of the central field of view of the imaging plane. In addition, the circumferential region 24 of the object side surface 21 of the second lens 20 is convex, the circumferential region 44 of the object side surface 41 of the fourth lens 40 is concave, and the circumferential region 47 of the image side surface 42 of the fourth lens 40 is convex, which can further correct the distortion of the edge field of view. The preferred range of (ALT+BFL+ImgH) / G12 is 1.300≤(ALT+BFL+ImgH) / G12≤2.450.

[0148] 5. In the optical imaging lens of the present invention, by adjusting the proportional relationship between the total thickness (ALT), back focal length (BFL), and image height (ImgH) of each lens and the air gap (G12) between the first lens 10 and the second lens 20, and satisfying the proportional constraint (ALT+BFL+ImgH) / G12≤2.450, the first lens, which meets the appearance requirements, can be adapted to the other lenses, achieving the purpose of reducing size while simultaneously possessing better image quality. If the refractive index of the fourth lens 40 is positive and the image side surface 22 of the second lens 20 is... Conditions such as the optical axis region 26 being concave and the optical axis region 33 of the object side surface 31 of the third lens 30 being convex can correct the aberration of the central field of view of the imaging plane. In addition, the surface shape of the circumferential region of a specific lens, such as the circumferential region 24 of the object side surface 21 of the second lens 20 being convex and the circumferential region 44 of the object side surface 41 of the fourth lens 40 being concave, can further correct the distortion of the edge field of view. The optimal range of (ALT+BFL+ImgH) / G12 is 1.300≤(ALT+BFL+ImgH) / G12≤2.450.

[0149] 6. In the optical imaging lens of the present invention, by adjusting the total thickness (ALT) of each lens, the system focal length (EFL), and the air gap between the first lens 10 and the second lens to satisfy the ratio constraint (ALT+EFL) / G12≤1.950, the first lens 10, which meets the appearance requirements, can be adapted to the other lenses to achieve the purpose of reducing size while having better imaging quality. If the optical axis region 23 of the object side 21 of the second lens 20 is convex, the optical axis region 26 of the image side 22 of the second lens 20 is concave, and the third lens... The optical axis region 33 of the object side surface 31 of the fourth lens 30 is convex, and the optical axis region 46 of the image side surface 42 of the fourth lens 40 is convex. These conditions can correct the aberrations in the central field of view of the imaging plane. In addition, the surface shape of the circumferential region of a specific lens, such as the circumferential region 44 of the object side surface 41 of the fourth lens 40 being concave and the circumferential region 47 of the image side surface 42 of the fourth lens 40 being convex, can further correct the distortion of the edge field of view. The preferred range of (ALT+EFL) / G12 is 1.000≤(ALT+EFL) / G12≤1.950.

[0150] 7. When the invention satisfies that the fourth lens 40 has a positive refractive index, it is beneficial to further reduce distortion aberrations.

[0151] 8. When the invention satisfies the conditions that the optical axis region 16 of the image side surface 12 of the first lens 10 is convex or the circumferential region 17 of the image side surface 12 of the first lens 10 is concave, the focal length of the system can be increased. If the conditions that the optical axis region 16 of the image side surface 12 of the first lens 10 is convex and the circumferential region 17 of the image side surface 12 of the first lens 10 is concave are simultaneously satisfied, the system size can be further reduced.

[0152] 9. When the invention satisfies conditions such as the optical axis region 13 of the object side surface 11 of the first lens 10 being convex or the circumferential region 14 of the object side surface 11 of the first lens 10 being convex, longitudinal spherical aberration can be effectively improved.

[0153] 10. When the invention satisfies the conditions that the optical axis region 36 of the image side surface 32 of the third lens 30 is convex and the circumferential region 37 of the image side surface 32 of the third lens 30 is convex, it can effectively improve field curvature aberration. Furthermore, when combined with the condition that the circumferential region 33 of the object side surface 31 of the third lens 30 is convex, it can further improve longitudinal spherical aberration.

[0154] 11. When the invention satisfies the conditional range (ALT+BFL+ImgH) / G12≤2.450 or (ALT+EFL) / G12≤1.950, it is beneficial to reduce distortion.

[0155] 12. In order to shorten the length of the lens system and ensure image quality, while taking into account the ease of manufacturing, the air gap between lenses is reduced or the lens thickness is appropriately shortened, along with specific image height limitations. Under the numerical range of the conditions described in Table 1 below, the embodiments of the present invention can be configured to improve the aberrations and distortions of the optical imaging lens, and when the optimal range is met, spherical aberration can be further improved.

[0156] Table 1

[0157]

[0158]

[0159] 13. To achieve both high light throughput and good image quality, in addition to balancing the aperture value and system focal length to achieve a suitable entrance pupil diameter, it is also necessary to adjust the thickness of each lens and the air gap in the system. Under the numerical range of the conditions described in Table 2 below, the embodiments of the present invention can have a better configuration, improving aberrations and distortions of the optical imaging lens. When the optimal range is met, spherical aberration can be further improved.

[0160] Table 2

[0161] Conditional range better range Fno*AAG / ALT≥1.000 1.000≤Fno*AAG / ALT≤4.000 Fno*EFL / Tavg≤6.500 2.900≤Fno*EFL / Tavg≤6.500 Fno*(BFL+Tmin) / G12≤3.100 0.750≤Fno*(BFL+Tmin) / G12≤3.100 (T1+G12) / (Fno*Tmin)≥4.400 4.400≤(T1+G12) / (Fno*Tmin)≤10.000 TL / (Fno*Gmin)≤1.500 0.700≤TL / (Fno*Gmin)≤1.500

[0162] In addition, any combination of parameters in the embodiments can be selected to increase lens constraints, thereby facilitating lens design with the same architecture as the present invention.

[0163] In view of the unpredictability of optical system design, under the framework of the present invention, meeting the above conditions can better shorten the length of the system, have a small aperture value, have excellent optical quality, or improve the assembly yield and improve the shortcomings of the prior art. Furthermore, the use of plastic material for the lens in the embodiments of the present invention can further reduce the weight of the lens and save costs.

[0164] The numerical ranges, including the maximum and minimum values, obtained from the combined proportional relationships of the optical parameters disclosed in the various embodiments of the present invention can all be implemented accordingly.

[0165] The embodiments of this invention disclose optical parameters including, but not limited to, focal length, lens thickness, and Abbe number (Vd). For example, the present invention discloses an optical parameter A and an optical parameter B in various embodiments. The specific explanations of the ranges covered by these optical parameters, the comparative relationships between the optical parameters, and the conditional ranges covered by the multiple embodiments are as follows:

[0166] (1) The range covered by the optical parameters, for example: α2≤A≤α1 or β2≤B≤β1, where α1 is the maximum value of optical parameter A in multiple embodiments, α2 is the minimum value of optical parameter A in multiple embodiments, β1 is the maximum value of optical parameter B in multiple embodiments, and β2 is the minimum value of optical parameter B in multiple embodiments.

[0167] (2) Comparison of optical parameters, for example: A is greater than B or A is less than B.

[0168] (3) The conditional range covered by multiple embodiments, specifically, the combination or proportional relationships obtained by possible calculations of a plurality of optical parameters of the same embodiment, defined as E. E may be, for example: A+B or AB or A / B or A*B or (A*B). 1 / 2 E satisfies the condition E≤γ1 or E≧γ2 or γ2≤E≤γ1, where γ1 and γ2 are the values ​​obtained by calculation of optical parameter A and optical parameter B in the same embodiment, and γ1 is the maximum value in multiple embodiments of the present invention, and γ2 is the minimum value in multiple embodiments of the present invention.

[0169] The range covered by the aforementioned optical parameters, the comparative relationships between the optical parameters, and the maximum, minimum, and numerical ranges within these conditions are all features upon which the present invention can be implemented, and all fall within the scope disclosed in the present invention. The above are merely illustrative examples and should not be construed as limiting.

[0170] All embodiments of the present invention are feasible, and some feature combinations can be extracted from the same embodiment. Compared with the prior art, these feature combinations can achieve unexpected effects. These feature combinations include, but are not limited to, combinations of features such as surface shape, refractive index, and conditional features. The disclosure of the embodiments of the present invention is a specific example to illustrate the principles of the present invention and should not be limited to the disclosed embodiments. Furthermore, the embodiments and their accompanying drawings are only for illustrative purposes and are not limited thereto.

[0171] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall be covered by the present invention.

Claims

1. An optical lens, comprising, in sequence along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein each of the first lens to the fourth lens includes an object-side surface facing the object side and allowing light to pass through, and an image-side surface facing the image side and allowing light to pass through; characterized in that: A circumferential region on the image side of the first lens is concave. A circumferential region on the side of the object of the second lens is convex. The optical axis region on the image side of the second lens is concave; The optical axis region on the side of the third lens is convex. The optical axis region on the side of the fourth lens is concave; A circumferential region on the image side of the fourth lens is convex. The optical lens has only the four lenses mentioned above. D21t42 is the distance on the optical axis from the object side of the second lens to the image side of the fourth lens. BFL is the distance on the optical axis from the image side of the fourth lens to an imaging plane. G12 is the air gap between the first lens and the second lens on the optical axis. The optical lens satisfies the condition (D21t42+BFL) / G12≤2.

250.

2. An optical lens, comprising, in sequence along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein each of the first lens to the fourth lens includes an object-side surface facing the object side and allowing light to pass through, and an image-side surface facing the image side and allowing light to pass through; characterized in that: A circumferential region on the image side of the first lens is concave. A circumferential region on the side of the object of the second lens is convex. A circumferential region on the image side of the second lens is concave. The optical axis region on the side of the third lens is convex. The optical axis region on the side of the fourth lens is concave; A circumferential region on the image side of the fourth lens is convex. The optical lens has only the four lenses mentioned above. D21t42 is the distance on the optical axis from the object side of the second lens to the image side of the fourth lens. BFL is the distance on the optical axis from the image side of the fourth lens to an imaging plane. G12 is the air gap between the first lens and the second lens on the optical axis. The optical lens satisfies the condition (D21t42+BFL) / G12≤2.

250.

3. The optical lens as described in claim 1 or 2, characterized in that: Where AAG is the sum of the three air gaps of the first lens to the fourth lens on the optical axis, ImgH is the image height of the optical lens, and the optical lens satisfies the following condition: (AAG+BFL) / ImgH≥3.

500.

4. The optical lens as described in claim 1 or 2, characterized in that: Where Fno is an aperture value of the optical lens, AAG is the sum of the three air gaps of the first lens to the fourth lens on the optical axis, and ALT is the sum of the four lens thicknesses of the first lens to the fourth lens on the optical axis. The optical lens satisfies the following condition: Fno*AAG / ALT≥1.

000.

5. The optical lens as described in claim 1 or 2, characterized in that: Where ALT is the sum of the thicknesses of the four lenses from the first lens to the fourth lens on the optical axis, T1 is the thickness of the first lens on the optical axis, and the optical lens satisfies the following condition: ALT / (T1+G12)≤1.

000.

6. An optical lens, comprising, in sequence along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein each of the first lens to the fourth lens includes an object-side surface facing the object side and allowing light to pass through, and an image-side surface facing the image side and allowing light to pass through; characterized in that: The optical axis region on the image side of the first lens is concave; A circumferential region on the side of the object of the second lens is convex. The optical axis region on the image side of the second lens is concave; The optical axis region on the side of the third lens is convex. The optical axis region on the side of the fourth lens is concave; A circumferential region on the image side of the fourth lens is convex. The optical lens has only the four lenses mentioned above. ALT is the sum of the thicknesses of the four lenses from the first lens to the fourth lens on the optical axis. BFL is the distance from the image side of the fourth lens to an image plane on the optical axis. ImgH is the image height of the optical lens. G12 is the air gap between the first lens and the second lens on the optical axis, and satisfies the condition (ALT+BFL+ImgH) / G12≤2.

450.

7. An optical lens, comprising, in sequence along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein each of the first lens to the fourth lens includes an object-side surface facing the object side and allowing light to pass through, and an image-side surface facing the image side and allowing light to pass through; characterized in that: The optical axis region on the image side of the first lens is concave; A circumferential region on the side of the object of the second lens is convex. The optical axis region on the image side of the second lens is concave; The optical axis region on the side of the third lens is convex. A circumferential region on the side of the object of the fourth lens is concave. A circumferential region on the image side of the fourth lens is convex. The optical lens has only the four lenses mentioned above. ALT is the sum of the thicknesses of the four lenses from the first lens to the fourth lens on the optical axis. BFL is the distance from the image side of the fourth lens to an image plane on the optical axis. ImgH is the image height of the optical lens. G12 is the air gap between the first lens and the second lens on the optical axis, and satisfies the condition (ALT+BFL+ImgH) / G12≤2.

450.

8. An optical lens, comprising, in sequence along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein each of the first lens to the fourth lens includes an object-side surface facing the object side and allowing light to pass through, and an image-side surface facing the image side and allowing light to pass through; characterized in that: A circumferential region on the side of the object of the second lens is convex. The optical axis region on the image side of the second lens is concave; The optical axis region on the side of the third lens is convex. The fourth lens has a positive refractive index; A circumferential region on the side of the object of the fourth lens is concave. The optical lens has only the four lenses mentioned above. ALT is the sum of the thicknesses of the four lenses from the first lens to the fourth lens on the optical axis. BFL is the distance from the image side of the fourth lens to an image plane on the optical axis. ImgH is the image height of the optical lens. G12 is the air gap between the first lens and the second lens on the optical axis, and satisfies the condition (ALT+BFL+ImgH) / G12≤2.

450.

9. The optical lens as described in claim 6, 7, or 8, characterized in that: Where TTL is the distance from the object side of the first lens to the imaging surface on the optical axis, ImgH is the image height of the optical lens, and the optical lens satisfies the following condition: TTL / ImgH≥6.

500.

10. The optical lens as described in claim 1, 2, 6, 7, or 8, characterized in that: The optical lens satisfies the following condition: G12 / BFL ≥ 0.

750.

11. The optical lens as described in claim 1, 2, 6, 7, or 8, characterized in that: Where Fno is an aperture value of the optical lens, EFL is an effective focal length of the optical lens, Tavg is an average of the thicknesses of the four lenses from the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: Fno*EFL / Tavg≤6.

500.

12. The optical lens as described in claim 1, 2, 6, 7, or 8, characterized in that: Where TTL is the distance from the object side of the first lens to the imaging surface on the optical axis, AAG is the sum of the three air gaps of the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: TTL / (AAG+BFL)≤2.

100.

13. The optical lens as described in claim 1, 2, 6, 7, or 8, characterized in that: Where Fno is an aperture value of the optical lens, Tmin is a minimum value of the thickness of the four lenses from the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: Fno*(BFL+Tmin) / G12≤3.

100.

14. An optical lens, comprising, in sequence along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens, wherein each of the first lens to the fourth lens includes an object-side surface facing the object side and allowing light to pass through, and an image-side surface facing the image side and allowing light to pass through; characterized in that: The optical axis region on the side of the second lens is convex. The optical axis region on the image side of the second lens is concave; The optical axis region on the side of the third lens is convex. A circumferential region on the side of the object of the fourth lens is concave. The optical axis region on the image side of the fourth lens is convex. A circumferential region on the image side of the fourth lens is convex. The optical lens has only the four lenses mentioned above. ALT is the sum of the thicknesses of the four lenses from the first lens to the fourth lens on the optical axis. EFL is an effective focal length of the optical lens. G12 is an air gap between the first lens and the second lens on the optical axis, and satisfies the condition (ALT+EFL) / G12≤1.

950.

15. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where G23 is an air gap between the second lens and the third lens on the optical axis, G34 is an air gap between the third lens and the fourth lens on the optical axis, and the optical lens satisfies the following condition: G12 / (G23+G34)≧4.

000.

16. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where Gmax is the maximum value of the three air gaps of the first lens to the fourth lens on the optical axis, Tmin is the minimum value of the four lens thicknesses of the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: Gmax / Tmin≥4.

000.

17. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where T1 is the thickness of the first lens on the optical axis, T3 is the thickness of the third lens on the optical axis, T4 is the thickness of the fourth lens on the optical axis, and the optical lens satisfies the following condition: (T1+G12) / (T3+T4)≥3.

500.

18. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where T1 is the thickness of the first lens on the optical axis, Fno is the aperture value of the optical lens, Tmin is the minimum thickness of the four lenses from the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: (T1+G12) / (Fno*Tmin)≥4.

400.

19. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where Gmax is the maximum value of the three air gaps of the first lens to the fourth lens on the optical axis, and Gmin is the minimum value of the three air gaps of the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: Gmax / Gmin≥11.

000.

20. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where Tmax is the maximum value of the four lens thicknesses of the first lens to the fourth lens on the optical axis, Gmax is the maximum value of the three air gaps of the first lens to the fourth lens on the optical axis, and Tavg is the average value of the four lens thicknesses of the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: (Tmax+Gmax) / Tavg≥4.

200.

21. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where Tavg is the average thickness of the four lenses from the first lens to the fourth lens on the optical axis, Gavg is the average thickness of the three air gaps from the first lens to the fourth lens on the optical axis, G34 is the air gap between the third lens and the fourth lens on the optical axis, and the optical lens satisfies the following condition: (Tavg+Gavg) / G34≥5.

500.

22. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where TTL is the distance from the object side of the first lens to the imaging surface on the optical axis, AAG is the sum of the three air gaps of the first lens to the fourth lens on the optical axis, and the optical lens satisfies the following condition: TTL / AAG≤4.

000.

23. The optical lens as described in claim 1, 2, 6, 7, 8, or 14, characterized in that: Where TL is the distance on the optical axis from the object side of the first lens to the image side of the fourth lens, Fno is the aperture value of the optical lens, Gmin is the minimum value of the three air gaps between the first lens and the fourth lens on the optical axis, and the optical lens satisfies the following condition: TL / (Fno*Gmin)≤1.500.

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