Short-focus ultra-wide-angle lens structure

Abstract

The application discloses a short-focus super-wide-angle lens structure, which comprises front-group lenses, a middle main imaging lens and rear-group lenses arranged in sequence along the optical axis direction; a first air interval is formed between the front-group lenses and the middle main imaging lens, and a second air interval is formed between the middle main imaging lens and the rear-group lenses; the first object-side end surface of the front-group lenses is a convex aspheric surface, the first image-side end surface is a concave curved surface, and the vertex curvature radius R1 of the first object-side end surface is smaller than the vertex curvature radius R2 of the first image-side end surface; the second object-side end surface of the middle main imaging lens is a main focusing aspheric surface, and the second image-side end surface is a compensation curved surface; the third image-side end surface of the rear-group lenses is a convex curved surface; the axial length of the first air interval is d1, the axial length of the second air interval is d2, and d1>d2 is satisfied; the total optical length TTL of the lens structure satisfies TTL<=3.5mm; through the segmented refraction structure of three lenses and two air intervals, the collaborative design of short focus and super-wide angle is realized under the condition of extremely short total optical length.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to a short focal length ultra-wide-angle lens structure. Background Technology

[0002] With the miniaturization and integration of smart terminal devices, short-focal-length ultra-wide-angle lenses are widely used in robotic vacuum cleaners, smart door locks, security monitoring modules, vehicle-mounted auxiliary vision systems, and portable smart terminals. Especially in low-profile devices like robotic vacuum cleaners, where the camera module is typically positioned within a limited vertical height due to the limited thickness of the body, it still needs to achieve wide-range environmental perception to meet functional requirements such as path planning, obstacle avoidance, and spatial modeling. Therefore, the lens structure not only needs to have a large field of view but also needs to complete the imaging task with an extremely short total optical length. This places higher demands on the lens's focal length control, aberration correction capabilities, and structural compactness.

[0003] Existing ultra-wide-angle lenses typically employ a multi-element stacking method, achieving a large field of view by increasing the number of elements or enhancing the refractive power of individual elements. However, under the constraint of limited total optical length, simply relying on increasing refractive power to shorten the focal length can easily lead to aberration concentration, particularly making it difficult to effectively balance on-axis spherical aberration and mid-field aberration. At the same time, if the structural size is compressed by reducing the spacing between elements, the freedom of aberration adjustment in the system decreases, making it difficult to achieve a synergistic design that combines short focal length and a large field of view.

[0004] Therefore, achieving both short focal length and ultra-wide-angle imaging under limited optical length conditions remains a technical problem that urgently needs to be solved in existing lens structures. Summary of the Invention

[0005] The purpose of this invention is to provide a short focal length ultra-wide-angle lens structure to solve the above-mentioned technical problems.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A short-focal-length ultra-wide-angle lens structure includes: a front lens group, a central main imaging lens group, and a rear lens group arranged sequentially along the optical axis.

[0008] A first air gap is formed between the front lens group and the central main imaging lens, and a second air gap is formed between the central main imaging lens and the rear lens group.

[0009] The first object-side end face of the front lens is a convex aspherical surface, and its first image-side end face is a concave curved surface. The vertex radius of curvature R1 of the first object-side end face is smaller than the vertex radius of curvature R2 of the first image-side end face.

[0010] The second object-side end face of the central main imaging lens is a main focusing aspherical surface, and its second image-side end face is a compensating curved surface. The vertex radius of curvature R3 of the second object-side end face and the vertex radius of curvature R4 of the second image-side end face satisfy |R3|≠|R4|.

[0011] The third image-side end face of the rear lens group is a convex curved surface;

[0012] The axial length of the first air gap is d1, and the axial length of the second air gap is d2, and d1>d2.

[0013] The total effective optical focal length (EFL) of the front lens group, the central main imaging lens, and the rear lens group satisfies: 0.4mm ≤ EFL ≤ 0.9mm;

[0014] The total optical length (TTL) of the lens structure satisfies: TTL≤3.5mm.

[0015] Optionally, the front lens group includes a spacer step, an introductory easing zone, a support column, a front converging surface, and an extended correction surface arranged in sequence along the radial direction;

[0016] The spacer step is located at the outer edge of the front lens group and is used to limit the axial assembly distance between the front lens group and the central main imaging lens.

[0017] The introduction easing arc region is located in the outer peripheral region of the first object-side end face, and its radius of curvature is greater than the central radius of curvature of the first object-side end face.

[0018] The supporting column is a cylindrical structure disposed on the outer periphery of the front lens group, used to provide an assembly reference;

[0019] The front converging surface corresponds to the central region of the first object side end surface and is an aspherical structure with a vertex radius of curvature of R1.

[0020] The extended alignment surface corresponds to the first image-side end face, and its vertex radius of curvature is R2.

[0021] Optionally, the center thickness of the front lens group is CT1, and CT1 and the first air gap d1 satisfy CT1≤d1.

[0022] Optionally, the central main imaging lens includes a retraction limiting area, a reference cylindrical area, a stress relief groove, a main focusing surface, and a compensation correction surface arranged sequentially along the radial direction;

[0023] The retraction limiting area is located at the outer edge of the central main imaging lens and is used to form the first air gap with the front group of lenses;

[0024] The reference cylindrical area has an outer cylindrical structure and is used to control the coaxiality of the central main imaging lens.

[0025] The stress relief groove is located inside the reference cylindrical area to reduce the impact of material shrinkage on the main optical surface;

[0026] The main focusing surface corresponds to the second object side end surface and is an aspherical structure with a vertex radius of curvature of R3;

[0027] The compensation and correction surface corresponds to the second image-side end face, and its vertex radius of curvature is R4.

[0028] Optionally, the center thickness of the central imaging lens is CT2, and CT2 and the second air gap d2 satisfy CT2≥d2.

[0029] Optionally, the extended correction surface of the front lens group is disposed opposite to the main focusing surface of the central main imaging lens, and the two form the first air gap d1;

[0030] The axial distance between the vertex of the extended correction surface and the vertex of the main focusing surface is d1, and satisfies: 0.05mm≤d1≤0.6mm;

[0031] The vertex curvature radius R2 of the extended correction surface and the vertex curvature radius R3 of the main focal surface satisfy: |R3|<|R2|;

[0032] The center thickness CT1 of the front lens group and the center thickness CT2 of the central main imaging lens satisfy the following condition: CT2≥CT1.

[0033] Optionally, the rear lens group includes an outer peripheral guide area, a fixed diameter straight wall area, a folding compensation area, and a central bundle shaping area arranged radially in sequence.

[0034] in,

[0035] The peripheral guide area is located at the outer edge of the rear lens group and has a circular arc transition structure with a radius of R7.

[0036] The sizing straight wall area has a cylindrical structure and is used to fit and position itself against the inner wall of the lens barrel.

[0037] The angle compensation area corresponds to the end face of the third object and is a concave curved surface with a vertex radius of curvature of R5;

[0038] The central bundle shaping region corresponds to the third image-side end face and is a convex curved surface with a vertex radius of curvature of R6.

[0039] And it satisfies: |R5|>|R6|;

[0040] The axial length of the second air gap is d2, and satisfies: 0.02mm≤d2≤0.4mm;

[0041] The center thickness of the rear lens group is CT3, and CT3≤CT2.

[0042] Optionally, the lens structure further includes a lens barrel for accommodating the front lens group, the central main imaging lens, and the rear lens group;

[0043] The lens barrel is a one-piece molded structure, and its inner wall is provided with a first positioning step, a second positioning step and a third positioning step in sequence along the optical axis, which are used to define the axial positions of the front lens group, the central main imaging lens and the rear lens group respectively.

[0044] The outer wall of the lens barrel is provided with an external thread structure for threaded engagement with the mounting base.

[0045] The inner diameter Db of the lens tube satisfies:

[0046] Db≥max(D front group, D middle group, D rear group)+0.01mm.

[0047] Optionally, spacer lenses are provided between the front group lens and the central main imaging lens, and between the central main imaging lens and the rear group lens.

[0048] The spacer lens has a ring structure, and its inner diameter is larger than the effective light-transmitting aperture of the adjacent lens.

[0049] The axial thickness of the spacer lens corresponds to the formation of the first air gap d1 and the second air gap d2, respectively.

[0050] The outer diameter of the spacer lens matches the inner diameter of the lens barrel;

[0051] The axial thickness tolerance of the spacer lens is less than ±0.01 mm.

[0052] Optionally, the short focal length ultra-wide-angle lens structure also includes an infrared cut-off filter disposed on the image side of the rear lens group;

[0053] The infrared cut-off filter has a parallel flat plate structure with an optical thickness of t-IR, which satisfies the following condition: 0.1mm ≤ t-IR ≤ 0.5mm.

[0054] The effective light-passing diameter of the infrared cut-off filter is not less than the effective image circle diameter of the rear lens group.

[0055] Compared with the prior art, the present invention has the following beneficial effects: When light emitted from an external object enters the lens structure at a large incident angle, it first undergoes primary convergence through the convex aspherical surface of the first object-side end face of the front lens group, effectively converging the light from the large field of view and initially distributing the refractive power; subsequently, the light propagates through the first air gap to the central primary imaging lens, where the primary focusing aspherical surface of its second object-side end face performs primary refraction of paraxial light, controlling the system focal length and correcting on-axis spherical aberration, while the compensating surface of its second image-side end face, through a curvature distribution different from that of the primary focusing aspherical surface, affects the field of view and... The edge aberrations are balanced; the light then passes through the second air gap into the rear lens group, where the convex curved surface of the third image-side end face of the rear lens group reshapes and converges the direction of the principal ray, stabilizing the image plane position and completing the final aberration convergence; the refractive power is segmented and controlled by the air gap ratio of d1>d2, achieving short focal length ultra-wide-angle imaging under the structural constraints of EFL of 0.4mm~0.9mm and TTL≤3.5mm; this scheme achieves the coordinated design of short focal length and ultra-wide-angle under the condition of extremely short total optical length through the segmented refractive structure of three lenses and two cavities. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0057] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0058] Figure 1 This is a schematic diagram of the main structure of the short-focal-length ultra-wide-angle lens in this embodiment.

[0059] Figure 2 This is a cross-sectional structural diagram of the short focal length ultra-wide-angle lens structure in this embodiment 1;

[0060] Figure 3 This is a schematic diagram of the front lens element of the short-focal-length ultra-wide-angle lens structure in this embodiment.

[0061] Figure 4 This is a schematic diagram of the central main imaging lens in the short-focal-length ultra-wide-angle lens structure of this embodiment 1;

[0062] Figure 5 This is a schematic diagram of the rear lens element of the short focal length ultra-wide-angle lens structure in this embodiment.

[0063] Illustration: Front lens group 100, central main imaging lens 200, rear lens group 300, first air gap 10, second air gap 20, spacer step 101, guide arc zone 102, bearing column section 103, front converging surface 104, extension correction surface 105, retraction limit zone 201, reference cylindrical surface zone 202, stress relief groove 203, main focusing surface 204, compensation correction surface 205, peripheral guide zone 301, diameter straight wall zone 302, angle compensation zone 303, central beam shaping zone 304, lens barrel 400, spacer lens 500, infrared cutoff filter 600. Detailed Implementation

[0064] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0065] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0066] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0067] Combination Figures 1 to 5 As shown, this embodiment of the invention provides a short-focal-length ultra-wide-angle lens structure, including: a front lens group 100, a central main imaging lens 200, and a rear lens group 300 arranged sequentially along the optical axis; a first air gap 10 is formed between the front lens group 100 and the central main imaging lens 200, and a second air gap 20 is formed between the central main imaging lens 200 and the rear lens group 300.

[0068] Employing a three-element segmented refractive structure, the system's refractive power is distributed hierarchically along the optical axis by creating two independent air gaps between the front lens group 100, the central primary imaging lens 200, and the rear lens group 300. Compared to traditional compact stacked structures, this segmented layout provides additional degrees of freedom for aberration adjustment, allowing refractive power distribution and aberration control to be performed at different optical stages. This avoids concentrating excessive refractive stress on a single lens, which is beneficial for achieving short-focal-length designs within limited structural length constraints.

[0069] The first object-side end face of the front lens 100 is a convex aspherical surface, and its first image-side end face is a concave curved surface. The vertex radius of curvature R1 of the first object-side end face is smaller than the vertex radius of curvature R2 of the first image-side end face.

[0070] The front lens group 100 adopts a curvature distribution with a strong object-side curvature and a relatively gentle image-side curvature. Its structural feature is that the object-side end face undertakes the primary convergence of the main incident light rays, while the image-side end face uses a larger radius of curvature for refraction gradient transition. This arrangement can reduce the abrupt refraction of edge rays under large field-of-view incident conditions, allowing the incident beam to maintain a controllable wavefront shape before entering the central main imaging lens 200, thereby reducing the risk of accumulation of primary distortion and edge aberrations in the system.

[0071] The second object-side end face of the central main imaging lens 200 is a main focusing aspherical surface, and its second image-side end face is a compensating curved surface. The vertex radius of curvature R3 of the second object-side end face and the vertex radius of curvature R4 of the second image-side end face satisfy |R3|≠|R4|.

[0072] The central primary imaging lens 200 serves as the system's main refractive core. Its asymmetrical curvature at both ends allows the primary focusing surface 204 and the compensation surface to perform different aberration control tasks. The primary focusing surface 204 determines the system's focal length and controls on-axis spherical aberration, while the compensation surface performs secondary corrections for mid-range and edge aberrations. This unequal absolute curvature creates a differential distribution of refractive power, helping to maintain high image sharpness at high spatial frequencies.

[0073] The third image-side end face of the rear lens group 300 is a convex curved surface; it can correct the angle of light rays after passing through the central main imaging lens 200, thereby stabilizing the image plane position and improving edge imaging consistency.

[0074] The axial length of the first air gap 10 is d1, and the axial length of the second air gap 20 is d2, and the following condition is met: d1>d2.

[0075] The ratio of the first air gap 10 to the second air gap 20 is set so that there is a larger refractive coupling space between the front lens group 100 and the central main imaging lens 200, while the central main imaging lens 200 and the rear lens group 300 maintain a smaller image-side correction space.

[0076] The total effective optical focal length (EFL) of the front lens group 100, the central main imaging lens 200, and the rear lens group 300 satisfies: 0.4mm ≤ EFL ≤ 0.9mm;

[0077] Limiting the effective focal length to the range of 0.4mm to 0.9mm reflects the design orientation of this structure towards short-focal-length imaging. This focal length range, combined with the three-lens, two-air-spacer structure, allows the system to control aberration distribution through segmented refraction even at shorter focal lengths, avoiding the manufacturing difficulties and amplified surface shape errors caused by excessive curvature of a single lens.

[0078] The total optical length (TTL) of the lens structure satisfies: TTL ≤ 3.5mm. This limitation on the total optical length demonstrates the applicability of this structure in compact space conditions. By distributing the refractive power to three lens elements and utilizing two air gaps for segmented adjustment, a complete imaging system can still be formed even within a relatively small total optical length.

[0079] The working principle of this invention is as follows: When light emitted from an external object enters the lens structure at a large angle of incidence, it first undergoes primary convergence through the convex aspherical surface of the first object-side end face of the front lens group 100, effectively converging the large field-of-view light and initially distributing the refractive force; subsequently, the light propagates through the first air gap 10 to the central primary imaging lens 200, where the primary focusing aspherical surface of its second object-side end face performs primary refraction of paraxial light, controlling the system focal length and correcting on-axis spherical aberration; while the compensation surface of its second image-side end face, through a curvature distribution different from that of the primary focusing aspherical surface, corrects mid-field and edge aberrations. The light then passes through the second air gap 20 and enters the rear lens group 300. The convex curved surface of the third image-side end face of the rear lens group 300 reshapes and converges the direction of the principal ray, stabilizing the image plane position and completing the final aberration convergence. The refractive power is segmented and controlled by the air gap ratio of d1>d2, achieving short focal length ultra-wide-angle imaging under the structural constraints of EFL of 0.4mm~0.9mm and TTL≤3.5mm. This scheme achieves the coordinated design of short focal length and ultra-wide-angle under the condition of extremely short total optical length through the segmented refractive structure of three lenses and two cavities.

[0080] This lens structure utilizes a segmented refractive layout with three lenses and two air gaps to distribute refractive force into three stages: primary convergence in the front group, central master focus correction, and image-side convergence in the rear group. An independent degree of freedom for refractive adjustment is created through an air gap ratio of d1>d2, enabling the system to achieve a short focal length design and a wide field of view even with limited total optical length. Simultaneously, the combination of a convex aspherical surface in the front group and a central master focus aspherical surface, along with a compensating surface configuration based on asymmetrical curvature, effectively controls on-axis spherical aberration and mid-field aberration, improving imaging stability at high spatial frequencies. The overall structure achieves a balance between optical performance and structural compactness with an EFL of less than 1mm and a TTL of no more than 3.5mm, making it suitable for small, space-constrained smart devices.

[0081] Combination Figure 3 As shown in this embodiment, the front lens group 100 includes a spacer step 101, an introductory easing zone 102, a support column segment 103, a front converging surface 104, and an extension correction surface 105 arranged in a radial sequence.

[0082] The spacer step 101 is located at the outer edge of the front lens group 100 to limit the axial assembly distance between the front lens group 100 and the central main imaging lens 200.

[0083] The purpose of setting the spacer step 101 is to define the axial mounting position of the front lens group 100, thereby forming a stable first air gap 10 between it and the central main imaging lens 200. Unlike simply relying on the lens barrel 400 for positioning, this step structure can form an active positioning relationship on the lens body, thereby reducing the impact of assembly tolerances on the air gap size.

[0084] The soft-arc region 102 is set in the outer peripheral region of the first object side end face, and its radius of curvature is greater than the central radius of curvature of the first object side end face.

[0085] The introduced gradual curvature region 102 is located on the outer periphery of the object side, and its radius of curvature is larger than that of the central region, resulting in a relatively gentle refractive gradient in the outer periphery. This setting can mitigate the abrupt refraction of edge rays under large field-of-view incident conditions, reducing the risk of excessive deflection of edge rays.

[0086] The support column 103 is a cylindrical structure located on the outer periphery of the front lens group 100, used to provide an assembly reference. The support column 103 provides stable structural support for the lens and serves as an assembly reference surface that mates with the inner wall of the lens barrel 400.

[0087] The front converging surface 104 corresponds to the central region of the first object side end face and is an aspherical structure with a vertex radius of curvature of R1.

[0088] The front converging surface 104, as the main refractive surface on the object side, undertakes the primary converging task of the incident rays in the system. The use of an aspherical structure can provide a higher degree of refraction freedom under the condition of smaller volume. By introducing higher-order surface shape parameters to control the axial spherical aberration, the incident rays form a more ideal wavefront state before entering the central primary imaging lens 200.

[0089] The extended correction surface 105 corresponds to the first image-side end face, and its vertex radius of curvature is R2. The extended correction surface 105 is located on the image side, and its radius of curvature is larger than that of the front converging surface 104, causing the refractive intensity to decrease. This structure helps to complete the refractive transition within the front lens group 100, avoiding aberration concentration problems caused by strong convergence on the object side, while also providing smoother transition conditions for light propagation in the first air gap 10.

[0090] The center thickness of the front lens group 100 is CT1, and CT1 and the first air gap 10 d1 satisfy CT1≤d1.

[0091] The front lens group 100 is kept relatively thin and light in structure, while the first air gap 10 provides sufficient refractive transition space. This proportional relationship helps to avoid the front lens group 100 bearing too much refractive concentration burden, allowing the main refractive power to transition to the central main imaging lens 200, thereby optimizing the refractive power distribution structure and improving the stability of aberration adjustment while ensuring the system's compactness.

[0092] In summary, in this embodiment, the front lens group 100 achieves precise axial positioning through the spacer step 101, controls the edge incidence of the large field of view through the introduction of the gentle arc zone 102, ensures assembly stability through the bearing column section 103, and completes primary refraction and aberration pre-adjustment through the curvature distribution of the front converging surface 104 and the extended correction surface 105.

[0093] Combination Figure 4 As shown in this embodiment, the central main imaging lens 200 includes a retraction limiting area 201, a reference cylindrical area 202, a stress relief groove 203, a main focusing surface 204, and a compensation correction surface 205 arranged sequentially along the radial direction.

[0094] The retraction limiting area 201 is located at the outer edge of the central main imaging lens 200 to form a first air gap 10 with the front lens group 100; the retraction limiting area 201 is located at the outer edge of the lens, and its retraction structure is used to maintain a clear axial distance relationship with the front lens group 100.

[0095] The reference cylindrical area 202 is an outer cylindrical structure used to control the coaxiality of the central main imaging lens 200. The reference cylindrical area 202 is the main assembly and positioning area of ​​the central main imaging lens 200. Its cylindrical shape matches the inner wall of the lens barrel 400 to ensure that the optical axis of the lens is consistent with the optical axis of the system.

[0096] The stress relief groove 203 is located inside the reference cylindrical area 202 to reduce the impact of material shrinkage on the main optical surface. The stress relief groove 203 is located inside the reference cylindrical area 202 and its function is to break the continuity of the material in the radial direction, thereby relieving the transmission of internal stress generated during injection molding to the main optical area.

[0097] The main focusing surface 204 corresponds to the second object side end face and is an aspherical structure with a vertex radius of curvature of R3;

[0098] The principal focusing surface 204, as the core refractive surface of this lens, plays a decisive role in the system's focal length and on-axis aberrations. Its aspherical form allows for optimization of spherical aberration through higher-order surface parameters, effectively controlling light after it passes through the first air gap 10. This surface bears the main refractive load in the entire system; therefore, its radius of curvature R3 directly affects the system's focal length and image sharpness.

[0099] The compensation and correction surface 205 corresponds to the second image-side end face, and its vertex radius of curvature is R4. The radius of curvature R4 is different from that of the main focusing surface 204. Through the asymmetrical configuration of the curvatures on both sides, the central main imaging lens 200 corrects the mid-field and edge aberrations based on the main refraction. A second air gap 20 is formed between this surface and the rear lens group 300, providing a transition space for subsequent main ray shaping.

[0100] The center thickness of the central imaging lens 200 is CT2, and CT2 and the second air gap 20 d2 satisfy CT2≥d2.

[0101] Setting the center thickness CT2 of the central primary imaging lens 200 to be no less than the second air gap d2 helps ensure sufficient structural rigidity of the lens, while concentrating the refractive power primarily within the central lens body, rather than relying excessively on the air gap for adjustment. This proportional relationship helps maintain the stability of the system's aberration distribution.

[0102] In summary, the central primary imaging lens 200 in this embodiment achieves interval control through the retraction limiting region 201, ensures coaxial assembly through the reference cylindrical region 202, enhances surface stability through the stress relief groove 203, and achieves coordinated allocation of primary refraction and aberration compensation through the curvature difference between the primary focusing surface 204 and the compensation correction surface 205. Simultaneously, the proportional relationship between the center thickness and the second air gap 20 further strengthens the lens's core refractive position in the system, making it a key unit for achieving high-frequency imaging quality in the short-focal-length ultra-wide-angle lens structure.

[0103] Combination Figure 2As shown, in this embodiment, the extended correction surface 105 of the front lens group 100 is disposed opposite to the main focusing surface 204 of the central main imaging lens 200, and a first air gap 10 is formed between the two.

[0104] The axial distance between the vertex of the extended correction surface 105 and the vertex of the main focusing surface 204 is d1, and satisfies: 0.05mm≤d1≤0.6mm; within the above range, both refractive force transmission and aberration balance can be taken into account.

[0105] The vertex curvature radius R2 of the extended correction surface 105 and the vertex curvature radius R3 of the principal focusing surface 204 satisfy: |R3|<|R2|;

[0106] The absolute value of the curvature of the main focusing plane 204 is smaller than that of the extended focusing plane 105, meaning that the central main imaging lens 200 has a stronger refractive power. This curvature distribution method concentrates the main refractive task of the system on the central lens, while the front lens group 100 plays more of an incident buffer and transition role, thereby avoiding excessive refractive concentration at the front lens group 100, which is beneficial to suppressing the amplification of primary aberrations.

[0107] The center thickness CT1 of the front lens group 100 and the center thickness CT2 of the central main imaging lens 200 satisfy: CT2≥CT1.

[0108] The center thickness of the central primary imaging lens 200 is not less than that of the front lens group 100, which helps to improve its structural rigidity and surface stability. At the same time, this thickness ratio reflects the principle of matching refractive power with structural strength, that is, the lens that undertakes the main refractive function has a relatively larger solid thickness, thereby reducing the impact of processing errors on image quality.

[0109] In summary, through the comprehensive design of the relative setting of the extended correction surface 105 and the main focusing surface 204, the reasonable range control of the first air gap 10, the distribution relationship of the absolute value of curvature, and the proportional relationship of the center thickness, a segmented refractive cooperative structure between the front group lens 100 and the central main imaging lens 200 is realized. This enables the system to form a clear main refractive stage and transition stage under the condition of limited total optical length, which is beneficial to the balanced distribution of refractive power and aberration control in the short focal length ultra-wide-angle imaging structure.

[0110] Combination Figure 5 As shown in this embodiment, the rear lens group 300 specifically includes an outer peripheral guide area 301, a diameter straight wall area 302, an angle compensation area 303, and a central bundle shaping area 304 arranged radially in sequence.

[0111] in,

[0112] The peripheral inlet area 301 is located at the outer edge of the rear lens group 300 and has an arc transition structure with an arc radius of R7.

[0113] The sizing straight wall area 302 is a cylindrical structure used to mate with the inner wall of the lens barrel 400 for positioning;

[0114] The angle compensation area 303 corresponds to the end face of the third object and is a concave curved surface with a vertex radius of curvature of R5;

[0115] The central bundle shaping region 304 corresponds to the third image-side end face and is a convex curved surface with a vertex radius of curvature of R6; and satisfies: |R5|>|R6|;

[0116] This curvature relationship allows the image-side end face to bear a strong refractive capacity, which is used for the final convergence and shaping of paraxial rays. Through the cooperation of the concave compensation area and the convex shaping area, a refractive gradient distribution can be formed on the image side, thereby stabilizing the image plane position and improving edge uniformity.

[0117] The axial length of the second air gap 20 is d2, and satisfies: 0.02mm≤d2≤0.4mm; this ensures a small propagation distance between the central main imaging lens 200 and the rear lens group 300, which helps maintain the compactness of the overall system structure.

[0118] The center thickness of the rear lens group 300 is CT3, and CT3 ≤ CT2. The center thickness of the rear lens group 300 is no greater than that of the central primary imaging lens 200, which reflects the hierarchical principle of refractive power allocation, helps to control the overall length of the system and reduce the risk of material stress.

[0119] Combination Figure 2 As shown, in this embodiment, the lens structure also includes a lens barrel 400 for accommodating the front lens group 100, the central main imaging lens 200, and the rear lens group 300.

[0120] The lens barrel 400 is a one-piece molded structure. Its inner wall is provided with a first positioning step, a second positioning step and a third positioning step in sequence along the optical axis, which are used to define the axial positions of the front lens group 100, the central main imaging lens 200 and the rear lens group 300 respectively.

[0121] The outer wall of the lens barrel 400 is provided with an external thread structure for thread engagement with the mounting base.

[0122] The inner diameter Db of the 400mm lens barrel satisfies:

[0123] Db≥max(D front group, D middle group, D rear group)+0.01mm.

[0124] It should be noted that the lens barrel 400 adopts a one-piece molded structure, and its inner wall has positioning steps formed sequentially along the optical axis, so that each lens forms a stable hierarchical positioning relationship during assembly, thereby ensuring the consistency of air gap size and optical axis position. The outer wall of the lens barrel 400 is provided with an external thread structure for threaded engagement with the image sensor module or mounting base, and the overall installation and focus fine adjustment are achieved by screwing. At the same time, the inner diameter Db of the lens barrel 400 satisfies Db≥max(D front group, D middle group, D rear group)+0.01mm, so that the lens has a reasonable radial fit clearance after being installed in the lens barrel 400, which avoids assembly interference and stress concentration, and can maintain good coaxial stability with the positioning steps.

[0125] Combination Figure 2 As shown, in this embodiment, spacer lenses 500 are respectively provided between the front group lens 100 and the central main imaging lens 200 and between the central main imaging lens 200 and the rear group lens 300.

[0126] The spacer lens 500 has a ring structure with an inner diameter larger than the effective light-transmitting aperture of the adjacent lens; this ensures that light is not blocked by the structure when passing through the lens group, thereby avoiding mechanical vignetting.

[0127] The axial thickness of the spacer lens 500 corresponds to d1 forming the first air gap 10 and d2 forming the second air gap 20, respectively.

[0128] The outer diameter of the spacer lens is 500mm and the inner diameter of the lens barrel is 400mm to ensure stable positioning in the radial direction and maintain the coaxiality of the overall optical axis.

[0129] The axial thickness tolerance of the spacer lens 500 is less than ±0.01mm to reduce the impact of air gap size fluctuations on focal length and aberration distribution, thereby improving structural stability and imaging consistency during mass production.

[0130] In this embodiment, the lens structure also includes an infrared cut-off filter 600 disposed on the image side of the rear lens group 300.

[0131] The infrared cut-off filter 600 has a parallel flat plate structure with an optical thickness of t-IR, which satisfies the following condition: 0.1mm≤t-IR≤0.5mm;

[0132] The effective light transmission diameter of the infrared cut-off filter 600 is not less than the effective image circle diameter of the rear lens group 300.

[0133] The cutoff band of the infrared cutoff filter 600 is above 700nm.

[0134] It should be noted that the filter's impact on the optical path length is kept within a controllable range while ensuring mechanical strength, thereby avoiding significant focal length shift. The effective light-passing diameter of the infrared cut-off filter 600 is not less than the effective image circle diameter of the rear lens group 300, ensuring that the imaging beam passes through completely without edge obstruction. At the same time, its cut-off band is set above 700nm, so that the light entering the image sensor is mainly concentrated in the visible light range, thereby improving color reproduction accuracy and suppressing the interference of infrared stray light on image sharpness.

[0135] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A short-focal-length ultra-wide-angle lens structure, characterized in that, include: The front lens group, the central main imaging lens, and the rear lens group are arranged sequentially along the optical axis. A first air gap is formed between the front lens group and the central main imaging lens, and a second air gap is formed between the central main imaging lens and the rear lens group. The first object-side end face of the front lens is a convex aspherical surface, and its first image-side end face is a concave curved surface. The vertex radius of curvature R1 of the first object-side end face is smaller than the vertex radius of curvature R2 of the first image-side end face. The second object-side end face of the central main imaging lens is a main focusing aspherical surface, and its second image-side end face is a compensating curved surface. The vertex radius of curvature R3 of the second object-side end face and the vertex radius of curvature R4 of the second image-side end face satisfy |R3|≠|R4|. The third image-side end face of the rear lens group is a convex curved surface; The axial length of the first air gap is d1, and the axial length of the second air gap is d2, and d1>d2. The total effective optical focal length (EFL) of the front lens group, the central main imaging lens, and the rear lens group satisfies: 0.4mm ≤ EFL ≤ 0.9mm; The total optical length (TTL) of the lens structure satisfies: TTL≤3.5mm.

2. The short-focal-length ultra-wide-angle lens structure according to claim 1, characterized in that, The front lens group includes a spacer step, an introductory easing zone, a support column, a front converging surface, and an extended correction surface arranged in a radial sequence. The spacer step is located at the outer edge of the front lens group and is used to limit the axial assembly distance between the front lens group and the central main imaging lens. The introduction easing arc region is located in the outer peripheral region of the first object side end face, and its radius of curvature is greater than the central radius of curvature of the first object side end face. The supporting column is a cylindrical structure disposed on the outer periphery of the front lens group, used to provide an assembly reference; The front converging surface corresponds to the central region of the first object side end surface and is an aspherical structure with a vertex radius of curvature of R1. The extended alignment surface corresponds to the first image-side end face, and its vertex radius of curvature is R2.

3. The short-focal-length ultra-wide-angle lens structure according to claim 2, characterized in that, The center thickness of the front lens group is CT1, and CT1 and the first air gap d1 satisfy CT1≤d1.

4. The short-focal-length ultra-wide-angle lens structure according to claim 3, characterized in that, The central main imaging lens includes a retraction limiting area, a reference cylindrical area, a stress relief groove, a main focusing surface, and a compensation correction surface arranged in sequence along the radial direction. The retraction limiting area is located at the outer edge of the central main imaging lens and is used to form the first air gap with the front group of lenses; The reference cylindrical area has an outer cylindrical structure and is used to control the coaxiality of the central main imaging lens. The stress relief groove is located inside the reference cylindrical area to reduce the impact of material shrinkage on the main optical surface; The main focusing surface corresponds to the second object side end surface and is an aspherical structure with a vertex radius of curvature of R3; The compensation and correction surface corresponds to the second image-side end face, and its vertex radius of curvature is R4.

5. The short-focal-length ultra-wide-angle lens structure according to claim 4, characterized in that, The center thickness of the central imaging lens is CT2, and CT2 and the second air gap d2 satisfy CT2≥d2.

6. The short-focal-length ultra-wide-angle lens structure according to claim 5, characterized in that, The extended correction surface of the front lens group is positioned opposite to the main focusing surface of the central main imaging lens, and the two form the first air gap d1; The axial distance between the vertex of the extended correction surface and the vertex of the main focusing surface is d1, and satisfies: 0.05mm≤d1≤0.6mm; The vertex curvature radius R2 of the extended correction surface and the vertex curvature radius R3 of the main focal surface satisfy: |R3|<|R2|; The center thickness CT1 of the front lens group and the center thickness CT2 of the central main imaging lens satisfy the following condition: CT2≥CT1.

7. The short-focal-length ultra-wide-angle lens structure according to claim 1, characterized in that, The rear lens group includes an outer peripheral guide area, a fixed diameter straight wall area, a folding compensation area, and a central bundle shaping area arranged radially in sequence. in, The peripheral guide area is located at the outer edge of the rear lens group and has a circular arc transition structure with a radius of R7. The sizing straight wall area has a cylindrical structure and is used to fit and position itself against the inner wall of the lens barrel. The angle compensation area corresponds to the third object-side end face of the rear lens group and is a concave curved surface with a vertex radius of curvature of R5. The central bundle shaping region corresponds to the third image-side end face and is a convex curved surface with a vertex radius of curvature of R6. And it satisfies: |R5|>|R6|; The axial length of the second air gap is d2, and satisfies: 0.02mm≤d2≤0.4mm; The center thickness of the rear lens group is CT3, and CT3≤CT2.

8. The short-focal-length ultra-wide-angle lens structure according to claim 1, characterized in that, The lens structure also includes a lens barrel for accommodating the front lens group, the central main imaging lens, and the rear lens group; The lens barrel is a one-piece molded structure, and its inner wall is provided with a first positioning step, a second positioning step and a third positioning step in sequence along the optical axis, which are used to define the axial positions of the front lens group, the central main imaging lens and the rear lens group respectively. The outer wall of the mirror tube is provided with an external thread structure for threaded engagement with the mounting base. The inner diameter Db of the lens tube satisfies: Db≥max(D front group, D middle group, D rear group)+0.01mm.

9. The short-focal-length ultra-wide-angle lens structure according to claim 8, characterized in that, Spacer lenses are respectively provided between the front group lens and the central main imaging lens, and between the central main imaging lens and the rear group lens; The spacer lens has a ring structure, and its inner diameter is larger than the effective light-transmitting aperture of the adjacent lens. The axial thickness of the spacer lens corresponds to the formation of the first air gap d1 and the second air gap d2, respectively. The outer diameter of the spacer lens matches the inner diameter of the lens barrel; The axial thickness tolerance of the spacer lens is less than ±0.01 mm.

10. The short-focal-length ultra-wide-angle lens structure according to claim 1, characterized in that, It also includes an infrared cut-off filter disposed on the image side of the rear lens group; The infrared cut-off filter has a parallel flat plate structure with an optical thickness of t-IR, which satisfies the following condition: 0.1mm ≤ t-IR ≤ 0.5mm. The effective light-passing diameter of the infrared cut-off filter is not less than the effective image circle diameter of the rear lens group.

Images