Optical system, lens module and electronic device

Abstract

The application belongs to the optical field and specifically discloses an optical system, a lens module and electronic equipment, which contain: a first cemented lens with negative optical power, the incident surface and the emitting surface are concave surfaces at the near optical axis, and the cemented surface is a convex surface; a second cemented lens with negative optical power, the incident surface and the emitting surface are concave surfaces at the near optical axis, and the cemented surface is a convex surface; a first lens with positive optical power, the object side surface and the image side surface are both convex surfaces at the near optical axis; a third cemented lens with positive optical power, the incident surface and the emitting surface are convex surfaces at the near optical axis, and the cemented surface is a concave surface; a fourth cemented lens with positive optical power, the incident surface and the emitting surface are convex surfaces at the near optical axis, and the cemented surface is a concave surface; and a second lens with positive optical power, the object side surface is a convex surface at the near optical axis, and the image side surface is a concave surface. Through the application, the aberration problem is effectively solved, and the imaging quality is improved.

Description

Technical Field

[0001] This application belongs to the field of optics, and more specifically, relates to an optical system, a lens module, and an electronic device. Background Technology

[0002] With the rapid iteration of fields such as industrial automation, laser processing, and high-precision inspection, especially the widespread adoption of high-end applications such as multi-dimensional information reading, laser multi-dimensional lithography, microstructure imaging, and precision device inspection, more stringent requirements are being placed on the performance of optical lenses. Currently, the optical industry is upgrading towards miniaturization, high precision, and multi-functionality. Internal focusing technology, with its advantages of unchanged overall lens position during focusing, compact size, and high focusing accuracy, has become one of the core technologies for high-end optical lenses. Technological breakthroughs and patent layouts in related fields are accelerating, driving internal focusing lenses towards higher performance. These high-end applications not only require lenses with wide-spectrum adaptability to achieve clear imaging in both visible and near-infrared bands, but also need to meet the requirements of specific short working distances and fixed large numerical apertures. Simultaneously, precise focusing and aberration control are essential to ensure inspection accuracy and processing quality. This is also driving the rapid development of internal focusing optical systems towards miniaturization, high precision, and multi-functionality.

[0003] In core applications such as multidimensional information reading, laser multidimensional lithography, and high-precision imaging inspection, target imaging scenarios often involve multi-band adaptation. The entire visible light band is used for conventional high-definition imaging, while near-infrared segmented narrow bands are adapted to specific needs such as special material detection and imaging. This echoes the current application requirements of ultra-wideband grating technology in the near-infrared band, where accurate imaging has become one of the core requirements of high-end optical inspection. Simultaneously, the working environment of these applications typically requires the lens to operate at a short distance, ensuring numerical aperture stability within this range. This satisfies the accuracy requirements of high-end short-range imaging while balancing lens structural complexity and manufacturing feasibility, avoiding the problem of excessively high NA values ​​leading to a surge in lens manufacturing difficulty. This is also one of the key technical indicators of high-end short-range optical lenses.

[0004] Internal focusing technology, as the core solution for achieving precise focusing in optical lenses, has been widely used in products such as mirrorless cameras, macro lenses, and industrial inspection lenses due to its advantages of maintaining the overall lens position during focusing, compact size, and high focusing accuracy. Current internal focusing lenses mostly employ the movement of multiple lens groups to achieve focusing. However, in high-end applications requiring short working distances, wide spectral adaptability, and glass correction, existing internal focusing technologies still face many insurmountable technical bottlenecks. They cannot guarantee numerical aperture stability when the lens's working distance is within the short-range, and there is still significant room for innovation in related core technologies. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide an optical system, lens module and electronic device, which aims to solve the problem that the existing internal focusing technology still has many technical bottlenecks that are difficult to overcome in high-end application scenarios with short working distance, wide spectrum adaptation and glass correction.

[0006] To achieve the above objectives, in a first aspect, this application provides an optical system comprising, along the optical axis from the object side to the image side, the following components in sequence: The first cemented lens has negative optical power, with the incident surface being concave near the optical axis, the cemented surface being convex near the optical axis, and the exit surface being concave near the optical axis. The second cemented lens has negative optical power, with the incident surface being concave near the optical axis, the cemented surface being convex near the optical axis, and the exit surface being concave near the optical axis. The first lens has positive optical power, and both the object-side and image-side surfaces are convex near the optical axis. The third cemented lens has positive optical power, with the incident surface being convex near the optical axis, the cemented surface being concave near the optical axis, and the exit surface being convex near the optical axis. The fourth cemented lens has positive optical power, with the incident surface being convex near the optical axis, the cemented surface being concave near the optical axis, and the exit surface being convex near the optical axis. The second lens has positive optical power, with the object side being convex near the optical axis and the image side being concave near the optical axis.

[0007] The second cemented lens is movable along the optical axis to adjust the focal length of the optical system.

[0008] In one possible implementation, when the second cemented lens moves along the optical axis, the air gap D1 between the second cemented lens and the first cemented lens varies within the range of 38.296 mm ≤ D1 ≤ 45.948 mm, and the air gap D2 between the second cemented lens and the first lens varies within the range of 1.000 mm ≤ D2 ≤ 8.652 mm.

[0009] In one possible implementation, the air gap between the first lens and the third cemented lens is 15mm-20mm, the air gap between the third cemented lens and the fourth cemented lens is 1mm-3mm, and the air gap between the fourth cemented lens and the second lens is 0.1mm-1.1mm.

[0010] In one possible implementation, a beam-combining prism is further provided between the first lens and the third cemented lens; The beam combiner prism is used to combine a first-band beam incident along the optical axis from the object plane and a second-band beam incident perpendicular to the optical axis, and then output the combined beam along the optical axis to the image plane.

[0011] In one possible implementation, an aperture stop is further provided between the second cemented lens and the first lens; the aperture stop is disposed on the object side of the first lens.

[0012] In one possible implementation, the wavelength range of the first band beam is 450nm-1150nm, and the wavelength range of the second band beam is 350nm-430nm.

[0013] It should be noted that the aforementioned beam combining prism in this system can have high transmittance in the 450nm-1150nm band and high reflectance in the 350nm-430nm band, making it suitable for wide-band imaging and blue light beam combining coaxial servoing scenarios.

[0014] In one possible implementation, the air gap between the first lens and the beam combiner prism is 0.3mm-1.3mm, the air gap between the beam combiner prism and the third cemented lens is 0.3mm-1.3mm, the air gap between the third cemented lens and the fourth cemented lens is 1mm-3mm, and the air gap between the fourth cemented lens and the second lens is 0.1mm-1.1mm.

[0015] In one possible implementation, the object-side and image-side surfaces of the first lens are both aspherical, while the object-side and image-side surfaces of the second lens are both spherical.

[0016] In one possible implementation, the incident surface, cemented surface, and exit surface of the first cemented lens, the second cemented lens, the third cemented lens, and the fourth cemented lens are all spherical.

[0017] In one possible implementation, the radius of curvature R1 of the incident surface of the first cemented lens satisfies -25mm≤R1≤-15mm, the radius of curvature R2 of the cemented surface satisfies 5mm≤R2≤15mm, and the radius of curvature R3 of the exit surface satisfies 200mm≤R3≤300mm. The radius of curvature R4 of the incident surface of the second cemented lens satisfies -25mm≤R4≤-20mm, the radius of curvature R5 of the cemented surface satisfies 15mm≤R5≤25mm, and the radius of curvature R6 of the exit surface satisfies 150mm≤R6≤250mm. The radius of curvature R7 of the object side of the first lens satisfies 25mm≤R7≤35mm, and the radius of curvature R8 of the image side satisfies -25mm≤R8≤-15mm; The radius of curvature R9 of the incident surface of the third cemented lens satisfies 15mm≤R9≤25mm, the radius of curvature R10 of the cemented surface satisfies -25mm≤R10≤-15mm, and the radius of curvature R11 of the exit surface satisfies -55mm≤R11≤-45mm. The radius of curvature R12 of the incident surface of the fourth cemented lens satisfies 10mm≤R12≤20mm, the radius of curvature R13 of the cemented surface satisfies -20mm≤R13≤-10mm, and the radius of curvature R14 of the exit surface satisfies -30mm≤R14≤-20mm. The second lens has an object side radius of curvature R15 that satisfies 5mm≤R15≤15mm, and an image side radius of curvature R16 that satisfies 5mm≤R16≤15mm.

[0018] In one possible implementation, the first cemented lens, the second cemented lens, the third cemented lens, and the fourth cemented lens are all cemented together from the object side to the image side, and the difference in dispersion coefficient between the object-side lens and the image-side lens in each cemented lens is greater than 30.

[0019] In one possible implementation, the beam combiner prism comprises two cemented right-angle prisms, the light-transmitting surface of which is a high-transmittance anti-reflection coated surface, the cemented surface of which is a beam-splitting coated surface, and the non-light-transmitting surface of which is a frosted surface.

[0020] In one possible implementation, the beam-splitting coating has high transmittance for the first band beam and high reflectivity for the second band beam.

[0021] In one possible implementation, the center thickness of the object-side lens in the first cemented lens ranges from 7mm to 9mm, and the center thickness of the image-side lens ranges from 1mm to 3mm. The center thickness of the object-side lens in the second cemented lens ranges from 1mm to 3mm, and the center thickness of the image-side lens ranges from 1mm to 3mm. The center thickness of the first lens ranges from 3mm to 5mm; The center thickness of the object-side lens in the third cemented lens ranges from 3mm to 5mm, and the center thickness of the image-side lens ranges from 7mm to 9mm. The center thickness of the object-side lens in the fourth cemented lens ranges from 4mm to 6mm, and the center thickness of the image-side lens ranges from 7mm to 9mm. The center thickness of the second lens is 3mm-5mm.

[0022] In one possible implementation, the material of the object-side lens in the first cemented lens is H-K9L, and the material of the image-side lens is H-ZF2; The material of the object-side lens in the second cemented lens is H-LAK54, and the material of the image-side lens is H-FK61; The material of the first lens is D-FK95; The material of the object-side lens in the third cemented lens is H-FK95N, and the material of the image-side lens is H-LAF4; The material of the object-side lens in the fourth cemented lens is H-FK61, and the material of the image-side lens is H-TF3L; The material of the second lens is H-LAK7A.

[0023] In one possible implementation, the aperture of the aperture stop is in the range of 10mm-15mm.

[0024] In one possible implementation, the size of the beam-combining prism is in the range of A. 3 mm 3 The value of A ranges from 15mm to 17mm.

[0025] In a second aspect, this application provides a lens module, including a photosensitive chip and an optical system as described in the first aspect above, wherein the photosensitive chip is disposed on the image side of the optical system.

[0026] Thirdly, this application provides an electronic device including a housing and a lens module as described in the second aspect above, the lens module being disposed within the housing.

[0027] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: This application provides an optical system, a lens module, and an electronic device. The optical system employs an internal focusing variable working distance design and can be composed of multiple lens groups, including a front fixed cemented lens group, a movable cemented lens group, a middle fixed lens, two rear fixed cemented lens groups, and a rear fixed lens. The front fixed cemented lens group utilizes cost-effective optical materials and a spherical design, exhibiting low dispersion characteristics. The double cemented lens group simplifies chromatic aberration correction in the optical system. The materials possess excellent mechanical and chemical stability, providing good protection for the formed closed system. The movable cemented lens group is a key component for achieving the internal focusing function. By employing a movable cemented lens design, the materials and curvature design of the movable cemented lens group are optimized, enabling it to effectively correct light propagation differences caused by changes in working distance when moving within a small range, while maintaining a small range of focal length changes.

[0028] This application provides an optical system, lens module, and electronic device. The rear fixed lens group is responsible for accurately focusing the light, adjusted by the moving cemented lens group, onto the desired imaging plane. Its design takes into account the light propagation characteristics caused by variations in glass thickness, further correcting the main aberrations that may affect the system, such as spherical aberration and astigmatism, ensuring accurate imaging throughout the entire working distance. Furthermore, the optical system features a centrally located aperture on the object side of the central fixed lens, which optimizes aberration correction and makes the front and rear structures of the optical system more symmetrical. This effectively suppresses spherical aberration and chromatic aberration that are prone to occur in wide-band imaging, especially mitigating the aberration exacerbation caused by differences in light refraction across different wavelengths. Combined with a single cemented lens group, it can further improve aberration correction, adapting to the dual-band imaging requirements of 450nm-750nm and 750-1150nm, and solving the pain point of poor aberration control in existing lenses. It has stable light transmission performance. With a fixed numerical aperture of NA of 0.6, it can balance the amount of light transmitted on-axis and off-axis, avoid excessive attenuation of edge light, ensure uniform imaging illumination within a certain short working distance (such as 0.9mm-2.9mm), and ensure the clarity of microscopic detail imaging, which meets the needs of high-precision detection and multi-dimensional information reading. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the optical system structure without a beam-combining prism provided in the embodiments of this application; Figure 2 This is a schematic diagram of the optical system structure corresponding to the first working distance when a beam-combining prism is provided in the embodiments of this application; Figure 3 This is a schematic diagram of the optical system structure corresponding to the second working distance when a beam-combining prism is provided in the embodiments of this application; Figure 4 This is a schematic diagram of the optical system structure corresponding to the third working distance when a beam-combining prism is provided in the embodiments of this application; Figure 5 This is provided by the embodiments of this application. Figure 2 Schematic diagram of the transfer function curve of the corresponding optical system; Figure 6 This is provided by the embodiments of this application. Figure 3 Schematic diagram of the transfer function curve of the corresponding optical system; Figure 7 This is provided by the embodiments of this application. Figure 4 Schematic diagram of the transfer function curve of the corresponding optical system; Figure 8 This is provided by the embodiments of this application. Figure 2 Schematic diagram of field curvature aberration of the corresponding optical system; Figure 9 This is provided by the embodiments of this application. Figure 3 Schematic diagram of field curvature aberration of the corresponding optical system; Figure 10 This is provided by the embodiments of this application. Figure 4 Schematic diagram of field curvature aberration of the corresponding optical system; Figure 11 This is provided by the embodiments of this application. Figure 2 Schematic diagram of the corresponding optical system wavefront; Figure 12 This is provided by the embodiments of this application. Figure 3 Schematic diagram of the corresponding optical system wavefront; Figure 13 This is provided by the embodiments of this application. Figure 4 Schematic diagram of the corresponding optical system wavefront; Figure 14 This is a schematic diagram of the lens module structure provided in an embodiment of this application; Figure 15 This is a schematic diagram of the electronic device structure provided in the embodiments of this application.

[0030] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the beam combiner prism, 5 is the fourth lens, 6 is the fifth lens, 7 is glass; 10 is the optical system, 20 is the photosensitive chip; 100 is the lens module, 200 is the housing. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] Furthermore, throughout this specification, references to "an embodiment"; "an embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. Therefore, the appearance of the phrase "in one embodiment;" throughout this specification, and similar language, may, but not necessarily, refer to the same embodiment.

[0034] Figure 1 This is a schematic diagram of the optical system structure without a beam-combining prism provided in the embodiments of this application; as shown... Figure 1 As shown, along the optical axis from the object side to the image side, it includes the following in sequence: The first cemented lens 1 has negative optical power, with the incident surface being concave near the optical axis, the cemented surface being convex near the optical axis, and the exit surface being concave near the optical axis. The second cemented lens 2 has negative optical power, with the incident surface being concave near the optical axis, the cemented surface being convex near the optical axis, and the exit surface being concave near the optical axis. The first lens 3 has positive optical power, and both the object side and the image side are convex near the optical axis. The third cemented lens 5 has positive optical power, with the incident surface being convex near the optical axis, the cemented surface being concave near the optical axis, and the exit surface being convex near the optical axis. The fourth cemented lens 6 has positive optical power, with the incident surface being convex near the optical axis, the cemented surface being concave near the optical axis, and the exit surface being convex near the optical axis. The second lens 7 has positive optical power, with the object side being convex near the optical axis and the image side being concave near the optical axis.

[0035] The second cemented lens 2 is movable along the optical axis to adjust the focal length of the optical system.

[0036] In one embodiment, when the second cemented lens 2 moves along the optical axis, the air gap D1 between the second cemented lens 2 and the first cemented lens 1 varies within the range of 38.296mm≤D1≤45.948mm, and the air gap D2 between the second cemented lens 2 and the first lens 3 varies within the range of 1.000mm≤D2≤8.652mm.

[0037] In one embodiment, the air gap between the first lens 3 and the third cemented lens 5 is 15mm-20mm, the air gap between the third cemented lens 5 and the fourth cemented lens 6 is 1mm-3mm, and the air gap between the fourth cemented lens 6 and the second lens 7 is 0.1mm-1.1mm.

[0038] In a specific application scenario, the aforementioned optical system typically has a target object (such as glass of a certain thickness) positioned on its image side. This target object can be positioned starting from the minimum working distance. The minimum working distance refers to the closest distance the target object can be to the optical system. Furthermore, when... Figure 1 When the optical system shown operates on glass with a thickness of 0mm-2mm, the minimum working distance can be 0.9mm.

[0039] For example, by adjusting the position of the second cemented lens 2 along the optical axis in the optical system, while keeping the position of the optical system unchanged, focusing can be achieved by focusing only through a single set of cemented lenses, thus realizing the focusing correction function of glass with a thickness of 0mm-2mm. This effectively controls the optical system to focus at high quality to different working distances and effectively solves aberration problems.

[0040] Optionally, after the aforementioned optical system is packaged into a lens module, the internal focusing mechanism consists of a high-precision miniature guide rail and a drive unit. The guide rail uses special materials and processing techniques to ensure dimensional stability under temperature changes and long-term use, thus ensuring the precise axial and radial position of the lens during movement. The drive unit can precisely control the movement of the middle lens group with extremely small displacements, meeting the micro-displacement requirements of the system's multi-dimensional information reading.

[0041] In one embodiment, an aperture stop is further provided between the second cemented lens 2 and the first lens 3; the aperture stop is disposed on the object side of the first lens 3.

[0042] Specifically, the centrally positioned system aperture facilitates optimized aberration correction, making the optical system's front and rear structures more symmetrical. This effectively suppresses spherical and chromatic aberrations that are prone to occur in wide-band imaging, and particularly alleviates the aberration exacerbation caused by differences in light refraction across different wavelengths. Combined with a single set of cemented lenses, it can further enhance aberration correction, addressing the pain point of poor aberration control in existing lenses. It also features stable light transmission performance, balancing the amount of on-axis and off-axis light transmission at a fixed numerical aperture, avoiding excessive attenuation of edge light, ensuring uniform imaging illumination within a certain short working distance, and guaranteeing the clarity of microscopic details, thus meeting the needs of high-precision detection and multi-dimensional information reading.

[0043] Figure 2 This is a schematic diagram of the optical system corresponding to the first working distance when a beam-combining prism is provided in an embodiment of this application; as shown... Figure 2 As shown, a beam-combining prism 4 is also provided between the first lens 3 and the third cemented lens 5; The beam combiner prism 4 is used to combine the first band beam incident from the object plane along the optical axis and the second band beam incident perpendicular to the optical axis, and to emit the combined beam out along the optical axis to the image plane.

[0044] Understandably, a fixed beam combining prism 4 can be added as a key component for subsequent illumination or servo beam combining modules. The servo optical path can be expanded and shaped before being connected to the main optical path via a threaded connection, adding closed-loop control for stable imaging of the system, enabling the system to be stably positioned on the required plane for information extraction; the illumination optical path can also be combined with the main optical path via a threaded connection to achieve clear imaging requirements.

[0045] In one embodiment, the wavelength range of the first band beam is 450nm-1150nm, and the wavelength range of the second band beam is 350nm-430nm.

[0046] It should be noted that the aforementioned beam combining prism 4 in this system can have high transmittance in the 450nm-1150nm band and high reflectance in the 350nm-430nm band, making it suitable for wide-band imaging and blue light beam combining coaxial servo scenarios.

[0047] In one embodiment, the air gap between the first lens 3 and the beam combiner prism 4 is 0.3mm-1.3mm, the air gap between the beam combiner prism 4 and the third cemented lens 5 is 0.3mm-1.3mm, the air gap between the third cemented lens 5 and the fourth cemented lens 6 is 1mm-3mm, and the air gap between the fourth cemented lens 6 and the second lens 7 is 0.1mm-1.1mm.

[0048] In one embodiment, the object-side surface and the image-side surface of the first lens 3 are both aspherical, and the object-side surface and the image-side surface of the second lens 7 are both spherical.

[0049] In one embodiment, the incident surface, cemented surface, and exit surface of the first cemented lens 1, the second cemented lens 2, the third cemented lens 5, and the fourth cemented lens 6 are all spherical.

[0050] In one embodiment, the radius of curvature R1 of the incident surface of the first cemented lens 1 satisfies -25mm≤R1≤-15mm, the radius of curvature R2 of the cemented surface satisfies 5mm≤R2≤15mm, and the radius of curvature R3 of the exit surface satisfies 200mm≤R3≤300mm. The radius of curvature R4 of the incident surface of the second cemented lens 1 satisfies -25mm≤R4≤-20mm, the radius of curvature R5 of the cemented surface satisfies 15mm≤R5≤25mm, and the radius of curvature R6 of the exit surface satisfies 150mm≤R6≤250mm. The radius of curvature R7 of the object side of the first lens 3 satisfies 25mm≤R7≤35mm, and the radius of curvature R8 of the image side satisfies -25mm≤R8≤-15mm; The radius of curvature R9 of the incident surface of the third cemented lens 5 satisfies 15mm≤R9≤25mm, the radius of curvature R10 of the cemented surface satisfies -25mm≤R10≤-15mm, and the radius of curvature R11 of the exit surface satisfies -55mm≤R11≤-45mm. The radius of curvature R12 of the incident surface of the fourth cemented lens 6 satisfies 10mm≤R12≤20mm, the radius of curvature R13 of the cemented surface satisfies -20mm≤R13≤-10mm, and the radius of curvature R14 of the exit surface satisfies -30mm≤R14≤-20mm. The second lens 7 has an object side radius of curvature R15 that satisfies 5mm≤R15≤15mm, and an image side radius of curvature R16 that satisfies 5mm≤R16≤15mm.

[0051] In one embodiment, the first cemented lens 1, the second cemented lens 2, the third cemented lens 5, and the fourth cemented lens 6 are all cemented together from two lenses along the object side to the image side, and the difference in dispersion coefficient between the object-side lens and the image-side lens in each cemented lens is greater than 30.

[0052] In one embodiment, the beam-combining prism 4 includes two glued right-angle prisms, the light-transmitting surface of which is a high-transmittance anti-reflection coated surface, the glued surface of which is a beam-splitting coated surface, and the non-light-transmitting surface of which is a frosted surface.

[0053] In one embodiment, the beam-splitting coating has high transmittance for the first wavelength beam and high reflectivity for the second wavelength beam. That is, the beam-combining prism has high transmittance in the 450nm-1150nm wavelength band and high reflectivity in the 350nm-430nm wavelength band, making it suitable for wide-band imaging and blue light beam combining and coaxial servo applications.

[0054] In one embodiment, the center thickness of the object-side lens in the first cemented lens 1 ranges from 7mm to 9mm, and the center thickness of the image-side lens ranges from 1mm to 3mm. The center thickness of the object-side lens in the second cemented lens 2 ranges from 1mm to 3mm, and the center thickness of the image-side lens ranges from 1mm to 3mm. The center thickness of the first lens 3 ranges from 3mm to 5mm; The center thickness of the object-side lens in the third cemented lens 5 ranges from 3mm to 5mm, and the center thickness of the image-side lens ranges from 7mm to 9mm. The center thickness range of the object-side lens in the fourth cemented lens 6 is 4mm-6mm, and the center thickness range of the image-side lens is 7mm-9mm. The center thickness of the second lens 7 is 3mm-5mm.

[0055] In one embodiment, the aperture of the aperture stop ranges from 10mm to 15mm.

[0056] In one embodiment, the size range of the beam-combining prism 4 is A. 3 mm 3 The value of A ranges from 15mm to 17mm.

[0057] This application aims to provide an internal focusing lens optical system, the above-mentioned Figure 1 and Figure 2The provided optical system and related parameters enable internal focusing, suitable for the entire visible light band of 450nm-750nm and segmented narrow bands within 750nm-1150nm, with a working distance ranging from 0.9mm to 2.9mm and a focal length (NA) of 0.6 (NA approximately equal to D / 2f, where D represents the aperture diameter and f represents the focal length). While maintaining the lens position, single-group cemented lens focusing achieves 0mm-2mm in-glass correction, effectively resolving aberration issues and improving image quality. The system includes a reserved module for adding servo or illumination, further enhancing system stability to meet the needs of multi-dimensional information reading, high-precision optical imaging, and inspection applications.

[0058] Among them, the above Figure 1 and Figure 2 The optical system parameters shown are as follows: numerical aperture NA: 0.6; focal length f: 3.9mm-4.0mm; dominant wavelength: 450nm-1150nm (which can be divided into the entire visible light band of 450nm-750nm and the segmented narrow band within 750nm-1150nm), and the correction of glass with different thicknesses of 0mm-2mm is achieved through internal focusing; total optical length: 120mm (see the total thickness of cemented lens 1 to lens 7 in Table 1).

[0059] In a more specific embodiment, the above Figure 2 In the optical system shown, the parameters of each optical element are as shown in Table 1: Table 1 System Optical Component Parameter Table In Table 1, surfaces 1-3 represent the incident surface, cementing surface, and exit surface of the first cemented lens (cemented lens 1), respectively; surfaces 4-6 represent the incident surface, cementing surface, and exit surface of the second cemented lens (cemented lens 2), respectively; surfaces 7 and 8 represent the side of the first lens (lens 3) near the object plane and the side near the image plane, respectively; surfaces 9 and 10 can represent the side of the beam-combining prism (lens 4) near the object plane and the side near the image plane, respectively; surfaces 11-13 can represent the incident surface, cementing surface, and exit surface of the third cemented lens (cemented lens 5); surfaces 14-16 can represent the incident surface, cementing surface, and exit surface of the fourth cemented lens (cemented lens 6); and surfaces 17 and 18 can represent the side of the second lens (lens 7) near the object plane and the side near the image plane, respectively.

[0060] Among them, lens 8 represents the target object, namely glass with a thickness of d.

[0061] Those skilled in the art will understand that the side of a lens closer to the object plane is usually called the object side, and the side closer to the image plane is called the image side. This application will not make any further special explanation of the above concepts.

[0062] The thickness of surface 1 can represent the distance from the incident surface to the cemented surface of the first cemented lens (cemented lens 1), the thickness of surface 2 can represent the distance from the cemented surface to the exit surface of the first cemented lens (cemented lens 1), the thickness D1 of surface 3 can represent the distance from the exit surface of the first cemented lens (cemented lens 1) to the incident surface of the second cemented lens (cemented lens 2), and the same applies to surfaces 4-18.

[0063] In one embodiment, the material of the object-side lens in the first cemented lens 1 is H-K9L, and the material of the image-side lens is H-ZF2; The material of the object-side lens in the second cemented lens 2 is H-LAK54, and the material of the image-side lens is H-FK61; The material of the first lens 3 is D-FK95; The material of the object-side lens in the third cemented lens 5 is H-FK95N, and the material of the image-side lens is H-LAF4; The material of the object-side lens in the fourth cemented lens 6 is H-FK61, and the material of the image-side lens is H-TF3L; The material of the second lens 7 is H-LAK7A.

[0064] It should be noted that, referring to Table 1, both the object-side and image-side surfaces of the first lens are aspherical. In a specific embodiment, the aspherical coefficients of this optical system are shown in Table 2: Table 2 Aspherical Coefficients of Optical Systems Furthermore, the focus interval of this optical system varies as shown in Table 3 below: Table 3 Figure 1 and Figure 2 The table showing the focal interval variation of the optical system is provided. Figure 3 This is a schematic diagram of the optical system corresponding to the second working distance when a beam-combining prism is provided in the embodiments of this application; optionally, the second working distance is 1.9 mm.

[0065] Figure 4 This is a schematic diagram of the optical system corresponding to the third working distance when a beam-combining prism is provided in the embodiments of this application; optionally, the third working distance is 2.9 mm.

[0066] As can be seen from the first working distance to the third working distance mentioned above, the working distance range of the above optical system covers at least 0.9mm-2.9mm.

[0067] Figures 5 to 7 They are respectively Figures 2 to 4The diagram shows the modulation transfer function (MTF) curve of the corresponding optical system. The MTF curve represents the overall resolution of the optical system and describes the magnitude of the optical transfer function (OTF).

[0068] This optical system operates in the visible and near-infrared bands. See [link / reference] Figures 5 to 7 It can be seen that after balancing the performance and aberrations at different working distances, the MTF is greater than 0.2 at 1000LP / mm, which makes the system have high imaging quality.

[0069] Figures 8 to 10 They are respectively Figures 2 to 4 Schematic diagram of field curvature aberration of the corresponding optical system; Figures 8 to 10 As shown above, the axial chromatic aberration and astigmatism field curvature are both within ±2μm, and the distortion is within -0.5%. The aberrations are well corrected, which is beneficial for high-quality imaging.

[0070] Figures 11 to 13 They are respectively Figures 2 to 4 The diagram shows the wavefront of the corresponding optical system. It can be seen that at a working distance of 0.9 mm, the peak-to-valley (PV) error of the optical system is 0.1592λ, and the root mean square (RMS) error is 0.0434λ, where λ represents the wavelength. At a working distance of 1.9 mm, the wavefront PV error is 0.1492λ, and the RMS error is 0.0441λ. At a working distance of 2.9 mm, the wavefront PV error is 0.0490λ, and the RMS error is 0.0110λ.

[0071] Combination Figures 11 to 13 It can be seen that the PV of the wavefront of the optical system provided in this application embodiment is less than 0.2λ and the RMS is less than 0.05λ, which is beneficial for the optical system to achieve high resolution while making clear imaging.

[0072] like Figure 14 As shown, this application also provides a lens module, which includes a photosensitive chip 20 and the aforementioned... Figures 1 to 4The optical system 10 is shown. A photosensitive chip 20 is disposed on the image side of the optical system 10. The photosensitive surface of the photosensitive chip 10 is located on the imaging surface of the optical system 20. Light rays from an object passing through a lens and incident on the photosensitive surface can be converted into electrical signals for an image. The photosensitive chip 20 can be a complementary metal-oxide-semiconductor (CMOS) or a charge-coupled device (CCD). This lens module can be an imaging module integrated into an electronic device or a standalone lens. By incorporating the optical system provided in this application into the lens module, and by rationally designing the surface shape and refractive power of each lens in the optical system, focusing with a single set of cemented lenses while maintaining the lens position, 0mm-2mm in-glass correction can be achieved, effectively solving lens aberration problems and improving image quality.

[0073] See Figure 15 This application also provides an electronic device, which includes the aforementioned lens module 100 and housing 200, with the lens module 100 disposed within the housing 200. By incorporating the lens module 100 provided in this application into the electronic device, the device can possess continuous internal focusing functionality. This electronic device includes, but is not limited to, high-resolution biological imaging, microscopic topography measurement, micro / nano fabrication systems, industrial defect detection systems, and high-precision imaging systems.

[0074] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical system, characterized in that, Along the optical axis from the object side to the image side, it includes, in sequence: The first cemented lens has negative optical power, with the incident surface being concave near the optical axis, the cemented surface being convex near the optical axis, and the exit surface being concave near the optical axis. The second cemented lens has negative optical power, with the incident surface being concave near the optical axis, the cemented surface being convex near the optical axis, and the exit surface being concave near the optical axis. The first lens has positive optical power, and both the object-side and image-side surfaces are convex near the optical axis. The third cemented lens has positive optical power, with the incident surface being convex near the optical axis, the cemented surface being concave near the optical axis, and the exit surface being convex near the optical axis. The fourth cemented lens has positive optical power, with the incident surface being convex near the optical axis, the cemented surface being concave near the optical axis, and the exit surface being convex near the optical axis. The second lens has positive optical power, with the object side being convex near the optical axis and the image side being concave near the optical axis; The second cemented lens is movable along the optical axis to adjust the focal length of the optical system.

2. The optical system as described in claim 1, characterized in that, When the second cemented lens moves along the optical axis, the air gap D1 between the second cemented lens and the first cemented lens varies within the range of 38.296mm ≤ D1 ≤ 45.948mm, and the air gap D2 between the second cemented lens and the first lens varies within the range of 1.000mm ≤ D2 ≤ 8.652mm.

3. The optical system as described in claim 1, characterized in that, The air gap between the first lens and the third cemented lens is 15mm-20mm, the air gap between the third cemented lens and the fourth cemented lens is 1mm-3mm, and the air gap between the fourth cemented lens and the second lens is 0.1mm-1.1mm.

4. The optical system as claimed in claim 1, characterized in that, A beam-combining prism is also provided between the first lens and the third cemented lens; The beam combining prism is used to combine a first-band beam incident from the object plane along the optical axis and a second-band beam incident perpendicular to the optical axis, and to output the combined beam from the image plane along the optical axis. And / or the wavelength range of the first band beam is 450nm-1150nm, and the wavelength range of the second band beam is 350nm-430nm.

5. The optical system as claimed in claim 1, characterized in that, The object-side and image-side surfaces of the first lens are both aspherical, and the object-side and image-side surfaces of the second lens are both spherical; and / or the incident surface, cementing surface, and exit surface of the first cemented lens, the second cemented lens, the third cemented lens, and the fourth cemented lens are all spherical.

6. The optical system as claimed in claim 1, characterized in that, The radius of curvature R1 of the incident surface of the first cemented lens satisfies -25mm≤ R1≤-15mm, the radius of curvature R2 of the cemented surface satisfies 5mm≤ R2≤15mm, and the radius of curvature R3 of the exit surface satisfies 200mm≤ R3≤300mm. The radius of curvature R4 of the incident surface of the second cemented lens satisfies -25mm≤ R4≤-20mm, the radius of curvature R5 of the cemented surface satisfies 15mm≤ R5≤25mm, and the radius of curvature R6 of the exit surface satisfies 150mm≤ R6≤250mm. The radius of curvature R7 of the object side of the first lens satisfies 25mm ≤ R7 ≤ 35mm, and the radius of curvature R8 of the image side satisfies -25mm ≤ R8 ≤ -15mm; The radius of curvature R9 of the incident surface of the third cemented lens satisfies 15mm ≤ R9 ≤ 25mm, the radius of curvature R10 of the cemented surface satisfies -25mm ≤ R10 ≤ -15mm, and the radius of curvature R11 of the exit surface satisfies -55mm ≤ R11 ≤ -45mm. The radius of curvature R12 of the incident surface of the fourth cemented lens satisfies 10mm ≤ R12 ≤ 20mm, the radius of curvature R13 of the cemented surface satisfies -20mm ≤ R13 ≤ -10mm, and the radius of curvature R14 of the exit surface satisfies -30mm ≤ R14 ≤ -20mm. The second lens has an object side radius of curvature R15 that satisfies 5mm ≤ R15 ≤ 15mm, and an image side radius of curvature R16 that satisfies 5mm ≤ R16 ≤ 15mm.

7. The optical system as claimed in claim 1, characterized in that, The first, second, third, and fourth cemented lenses are all cemented together from the object side to the image side, and the difference in dispersion coefficient between the object-side and image-side lenses in each cemented lens is greater than 30; and / or the beam combiner prism comprises two cemented right-angle prisms, the light-transmitting surface of which is a high-transmittance anti-reflection coated surface, the cemented surface of which is a beam-splitting coated surface, and the non-light-transmitting surface of which is a frosted surface; the beam-splitting coated surface has high transmittance for the first band beam and high reflectivity for the second band beam.

8. The optical system as claimed in claim 4, characterized in that, The air gap between the first lens and the beam combiner prism is 0.3mm-1.3mm, the air gap between the beam combiner prism and the third cemented lens is 0.3mm-1.3mm, the air gap between the third cemented lens and the fourth cemented lens is 1mm-3mm, and the air gap between the fourth cemented lens and the second lens is 0.1mm-1.1mm. And / or the center thickness of the object-side lens in the first cemented lens ranges from 7mm to 9mm, and the center thickness of the image-side lens ranges from 1mm to 3mm; The center thickness of the object-side lens in the second cemented lens ranges from 1mm to 3mm, and the center thickness of the image-side lens ranges from 1mm to 3mm. The center thickness of the first lens ranges from 3mm to 5mm; The center thickness of the object-side lens in the third cemented lens ranges from 3mm to 5mm, and the center thickness of the image-side lens ranges from 7mm to 9mm. The center thickness of the object-side lens in the fourth cemented lens ranges from 4mm to 6mm, and the center thickness of the image-side lens ranges from 7mm to 9mm. The center thickness of the second lens is 3mm-5mm.

9. A lens module, characterized in that, It includes a photosensitive chip and an optical system as described in any one of claims 1 to 8, wherein the photosensitive chip is disposed on the image side of the optical system.

10. An electronic device, characterized in that, It includes a housing and a lens module as described in claim 9, wherein the lens module is disposed within the housing.

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