A doublet telecentric optical system, imaging detection method, device and medium

Abstract

This invention provides a dual-magnification telecentric optical system, imaging detection method, device, and medium, comprising: a common front lens group, a beam splitter, a first rear lens group, and a second rear lens group; the beam splitter is used to separate the incident light beam passing through the common front lens group into a first outgoing beam and a second outgoing beam, the optical axes of the two outgoing beams intersecting perpendicularly at the beam splitting surface of the beam splitter; the first rear lens group is disposed on the optical path of the first outgoing beam, forming a first-magnification telecentric optical path; the second rear lens group is disposed on the optical path of the second outgoing beam, forming a second-magnification telecentric optical path; wherein, the system aperture of the optical system is disposed on the beam splitting surface, thereby solving the problems of high hardware cost, low detection efficiency, and difficulty in accurately associating the field-of-view coordinates between multi-axis systems caused by using multiple sets of single-magnification telecentric lenses for time-division shooting in existing industrial vision inspection.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a double-magnification telecentric optical system, imaging detection method, device and medium. Background Technology

[0002] In the fields of precision manufacturing and automated assembly, machine vision inspection technology based on telecentric optical systems has become the mainstream solution for dimensional measurement and defect identification due to its low distortion, high precision, and parallax-free characteristics. Traditional telecentric lens designs typically follow a single-path, single-magnification architecture. As shown in commercially available industrial telecentric lenses, they contain only one coaxial optical path from the object plane to the image plane and provide a single optical magnification at a specific fixed working distance. However, with the improvement of inspection standards in industries such as electronics manufacturing and semiconductor packaging, different precision requirements often arise for the same inspection station. For example, in the automated optical inspection process of printed circuit boards, both large field-of-view, low-magnification imaging is needed to quickly locate the missing or offset of large-sized components (macroscopic defects), and small field-of-view, high-magnification imaging is needed to accurately measure the bridging or coplanarity deviation of fine-pitch chip pins (microscopic defects).

[0003] For the aforementioned multi-precision composite inspection scenarios, the current conventional approach is to configure two or more independent single-magnification telecentric optical systems, acquiring images at different magnifications through time-series shooting or station-by-station transfer. This approach has significant limitations in engineering practice: First, high hardware redundancy; the repetitive configuration of multiple lenses, cameras, and supporting light sources directly leads to increased system cost and installation space constraints. Second, limited inspection cycle time; mechanical switching or multiple exposure processes reduce production line throughput efficiency. Third, weak spatial coordinate correlation; physical deviations between different optical axis systems require complex secondary calibration algorithms to fit the field-of-view mapping relationship. Even so, mechanical vibration or thermal drift can easily cause misalignment of the region of interest between high and low magnification images, leading to misjudgments.

[0004] Therefore, there is an urgent need for a dual-magnification telecentric optical system to solve the technical problems of high hardware costs, low detection efficiency, and difficulty in accurately correlated field-of-view coordinates between multi-axis optical systems caused by using multiple single-magnification telecentric lenses for time-sharing in existing industrial vision inspection. Summary of the Invention

[0005] To overcome the problems existing in the related technologies, this disclosure provides a dual-magnification telecentric optical system, device, equipment, and medium to solve the technical problems of high hardware cost, low detection efficiency, and difficulty in accurately correlated field coordinates between multi-optical axis systems caused by using multiple sets of single-magnification telecentric lenses for time-sharing shooting in the related technologies.

[0006] This specification provides one or more embodiments of a double-magnification telecentric optical system, including a common front lens group, a beam splitter, a first rear lens group, and a second rear lens group arranged sequentially along the optical path: A beam splitter is used to separate an incident beam that has passed through the common front lens group into a first outgoing beam and a second outgoing beam, with the optical axes of the two outgoing beams intersecting perpendicularly at the beam splitting surface of the beam splitter. The first rear lens group is disposed in the optical path of the first emitted beam, forming a first magnification telecentric optical path; The second rear lens group is disposed in the optical path of the second emitted beam, forming a second magnification telecentric optical path; The system aperture of the optical system is disposed on the beam-splitting surface.

[0007] Preferably, the first-magnification telecentric optical path and the second-magnification telecentric optical path have a shared object-side working distance, and the ratio of the first magnification to the second magnification is 4:1; Both the first and second magnification telecentric optical paths have an aperture of F / 7.5, and can be adapted to an image plane diameter of 11mm.

[0008] Preferably, the common front lens group includes, from the object side to the image side, a first lens with positive optical power, a second lens with positive optical power, and a first cemented film. The first emitted beam is a beam transmitted through the beam splitter prism, and the first rear lens group includes, from the object side to the image side, a second cemented sheet, a third lens with positive optical power, a fourth lens with positive optical power, and a fifth lens with positive optical power. The second emitted beam is a beam reflected by the beam splitter prism, and the second rear lens group includes, from the object side to the image side, a third cemented sheet, a sixth lens with positive optical power, and a seventh lens with positive optical power.

[0009] Preferably, the object-side surface of the first lens is a plane, and the image-side surface is a convex surface; The object-side surface of the second lens is convex, and the image-side surface is concave. The first adhesive sheet consists of a first lens with positive optical power and a second lens with negative optical power, arranged sequentially from the object side to the image side. The object side of the first lens is convex and the image side is flat, while the object side of the second lens is flat and the image side is concave. The second laminate consists of a third lens with negative optical power and a fourth lens with positive optical power, arranged sequentially from the object side to the image side. The third laminate consists of a fifth lens with negative optical power and a sixth lens with positive optical power, arranged sequentially from the object side to the image side.

[0010] Preferably, the radius of curvature and material of the lens and the lamination meet the following conditions: The radius of curvature of the side surface of the first lens is -190mm ± 5%; The second lens has an object side curvature radius of 100mm ± 5% and an image side curvature radius of 170mm ± 5%. The first lens of the first laminate has an object-side curvature radius of 26mm ± 5%, and the second lens has an image-side curvature radius of 10mm ± 5%. The first lens is made of H-ZK3 material, and the second lens is made of H-LAK53 material; The first lens of the first laminate is made of H-FK61 material, and the second lens is made of H-ZK3A material.

[0011] Preferably, the total optical length of the optical system is 340mm ± 1%, wherein the optical spacing tolerance between the lenses in the common front lens group is ± 0.02mm, and the optical spacing tolerance between the lenses in the first rear lens group and the second rear lens group is ± 0.02mm.

[0012] This specification provides one or more embodiments of an imaging detection method using the above-described double-magnification telecentric optical system, comprising the following steps: Align the optical system with the object being measured so that the object surface is located at the common object-side working distance; The incident light passes sequentially through the shared front lens group and is then incident on the beam splitter. At the beam-splitting surface of the beam-splitting prism, the system aperture limits the beam aperture and splits the beam into transmitted light and reflected light; Transmitted light enters the first rear lens group and forms a telecentric image at a first magnification on the target surface of the first camera; The reflected light enters the second rear lens group and forms a telecentric image at a second magnification on the target surface of the second camera; The telecentric image at the first magnification and the telecentric image at the second magnification have the same field-of-view center coordinates.

[0013] Preferably, the first-magnification telecentric optical path and the second-magnification telecentric optical path have a shared object-side working distance, and the ratio of the first magnification to the second magnification is 4:1; Both the first and second magnification telecentric optical paths have an aperture of F / 7.5, and can be adapted to an image plane diameter of 11mm.

[0014] This specification provides one or more embodiments of a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the imaging detection method using the above-described double-magnification telecentric optical system.

[0015] This specification provides one or more embodiments of a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the imaging detection method using the double-magnification telecentric optical system described above.

[0016] The dual-magnification telecentric optical system, imaging detection method, device, and medium disclosed herein have the advantages of using a shared front lens group to perform preliminary focusing and aberration correction on the incident beam, providing a high-quality, large-field-of-view parallel or collimated optical path for subsequent beam splitting, ensuring consistent object-side imaging conditions for both telecentric optical paths; the beam splitter non-destructively and stably separates the incident beam, which has passed through the shared front lens group, into two outgoing beams with perpendicular optical axes, and the beam splitting surface achieves energy or spectral segmentation, ensuring that the two optical paths do not interfere with each other, while providing a spatially separated optical path basis for dual-magnification imaging; the first rear lens group receives the first outgoing beam. The first beam forms the first telecentric optical path, achieving imaging at a specific magnification while maintaining the object-side telecentric characteristics, eliminating perspective errors, and ensuring measurement accuracy. The second rear lens group receives the second outgoing beam, forming the second telecentric optical path, achieving a different magnification than the first path, providing complementary imaging capabilities for high resolution or large field of view, and meeting the needs of simultaneous observation at multiple scales. The system aperture is set on the beam splitter so that the system aperture is located at the conjugate position of the two rear lens groups, ensuring that the two telecentric optical paths share the same aperture aperture, synchronously controlling the direction of the principal ray, simplifying the structure, and reducing magnification chromatic aberration and parallax between the two optical paths. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in 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 recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a double-magnification telecentric optical system provided for one or more embodiments of this specification; Figure 2 System architecture diagrams provided for one or more embodiments of this specification; Figure 3A schematic diagram of a 0.436x telecentric 2D optical path structure and a schematic diagram of a 0.109x telecentric 2D optical path structure provided for one or more embodiments of this specification; Figure 4 A schematic diagram of a 0.109x telecentric 2D optical path structure provided for one or more embodiments of this specification; Figure 5 0.436x telecentric sector plot provided for one or more embodiments of this specification; Figure 6 A 0.109x telecentric sector plot provided for one or more embodiments of this specification; Figure 7 A schematic diagram of field curvature and distortion of a 0.436x telecentric system provided for one or more embodiments of this specification; Figure 8 A schematic diagram of field curvature and distortion of a 0.109 times telecentric system provided for one or more embodiments of this specification; Figure 9 A schematic diagram of the MTF curve of a 0.436 times telecentric system provided for one or more embodiments of this specification; Figure 10 A schematic diagram of the MTF curve of a 0.109 times telecentric system provided for one or more embodiments of this specification; Figure 11 A schematic diagram of the image plane illumination of a 0.436x telecentric system provided for one or more embodiments of this specification; Figure 12 A schematic diagram of the image plane illumination of a 0.109 times telecentric system provided for one or more embodiments of this specification; Figure 13 A schematic diagram of the dispersion circle distribution of a 0.436x telecentric system provided for one or more embodiments of this specification; Figure 14 A schematic diagram of the dispersion circle distribution of a 0.109-fold telecentric system provided for one or more embodiments of this specification; Figure 15 This is a schematic flowchart illustrating an imaging detection method using a double-magnification telecentric optical system, provided for one or more embodiments of this specification. Figure 16 This is a schematic diagram of the structure of a computer device provided for one or more embodiments of this specification. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this invention.

[0020] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0021] System Implementation Examples According to embodiments of the present invention, a double-magnification telecentric optical system is provided, such as... Figure 1 The diagram shown is a structural schematic of the double-magnification telecentric optical system provided in this embodiment. According to this embodiment, the double-magnification telecentric optical system comprises, sequentially along the optical path, a common front lens group 11, a beam splitter 12, a first rear lens group 13, and a second rear lens group 14. The beam splitter 12 is used to separate the incident beam that has passed through the common front lens group 11 into a first outgoing beam and a second outgoing beam, with the optical axes of the two outgoing beams intersecting perpendicularly at the beam splitting surface of the beam splitter 12.

[0022] The first rear lens group 13 is disposed in the optical path of the first emitted beam, forming a first magnification telecentric optical path, corresponding to outputting 0.436x telecentric imaging.

[0023] The second rear lens group 14 is disposed in the optical path of the second emitted beam, forming a second magnification telecentric optical path, corresponding to outputting 0.109x telecentric imaging.

[0024] The system aperture of the optical system is disposed on the beam-splitting surface. The lenses and apertures corresponding to the two optical paths are arranged in sequence with their respective optical axes as the rotation center, from left to right as follows: first lens 1, second lens 2, first cemented sheet 1, beam-splitting prism 12, second cemented sheet 2, third lens 3, fourth lens 4, fifth lens 5, third cemented sheet 3, sixth lens 6, and seventh lens 7. Among them, the beam-splitting prism 12 of the first lens 1, second lens 2, and first cemented sheet 1 is a common part of the two sets of optical paths. The two optical paths after the beam-splitting prism 12 are perpendicular to each other, corresponding to two imaging chips.

[0025] like Figure 2 The diagram shown is a system structure diagram provided in this embodiment.

[0026] The system provided in this embodiment uses a shared front lens group 11 to perform preliminary convergence and aberration correction on the incident beam, providing a high-quality, large-field-of-view parallel or collimated optical path for subsequent beam splitting, ensuring consistent object-side imaging conditions for the two telecentric optical paths. The beam splitter prism 12 non-destructively and stably separates the incident beam, which has passed through the shared front lens group, into two outgoing beams with perpendicular optical axes. The beam splitting surface achieves energy or spectral segmentation, ensuring that the two optical paths do not interfere with each other, and simultaneously providing a spatially separated optical path basis for double-magnification imaging. The first rear lens group 13 receives the first outgoing beam, forming a first-magnification telecentric beam. The optical path maintains the telecentric characteristics of the object side while achieving imaging at a specific magnification, eliminating perspective errors and ensuring measurement accuracy. The second rear lens group 14 receives the second outgoing beam, forming a second magnification telecentric optical path, achieving a different magnification than the first path, providing complementary imaging capabilities for high resolution or large field of view, and meeting the needs of simultaneous observation at multiple scales. The system aperture is set on the beam splitter so that the system aperture is located at the conjugate position of the two rear lens groups, ensuring that the two telecentric optical paths share the same aperture aperture, synchronously controlling the direction of the principal ray, simplifying the structure and reducing magnification chromatic aberration and parallax between the two optical paths.

[0027] In one embodiment, the first-magnification telecentric optical path and the second-magnification telecentric optical path share a common object-side working distance, and the ratio of the first magnification to the second magnification is 4:1. Specifically, the first magnification is 0.436 times and the second magnification is 0.109 times. The two imaging paths share the same object plane, the same field of view center, and the same working distance.

[0028] like Figure 3 The diagram shown is a schematic of the 0.436x telecentric 2D optical path structure provided in this embodiment. The 0.436x telecentric optical system consists of 5 sets of lenses, 2 sets of cemented plates, and a beam splitter arranged at certain optical intervals. The first lens 1, the second lens 2, and the first cemented plate 1 are shared by both magnifications. The leftmost side is the object plane of the system, and the rightmost side is the ideal image plane of the entire system. As shown in the figure above, the total optical length is 340mm.

[0029] like Figure 4 The diagram shown is a schematic of the 0.109x telecentric 2D optical path structure provided in this embodiment. The 0.109x telecentric optical system consists of four sets of lenses, two sets of cemented plates, and a beam splitter arranged at certain optical intervals. The first lens 1, the second lens 2, and the first cemented plate 1 are shared by both magnifications. The leftmost side is the object plane of the system, and the rightmost side is the ideal image plane of the entire system. As shown in the figure above, the total optical length is 227mm.

[0030] Both the first and second magnification telecentric optical paths have an F-number of F / 7.5, and can be adapted to an image plane diameter of 11mm. Within this image plane diameter range, the maximum optical distortion is less than 0.07%, and the relative illumination at the edge field of view is greater than 95%. The field of view at 0.436x magnification is 20.18mm*15.13mm, and the field of view at 0.109x magnification is 80.73mm*60.55mm (the field of view calculation reference chip size is 8.8mm*6.6mm), with a working distance of 126mm. The system operates in a visible light environment, with a designed operating wavelength between 486nm and 650nm, and a center wavelength of 550nm.

[0031] The system provided in this embodiment uses two telecentric optical paths to share the same object-side working distance, with a magnification ratio of 4:1. The aperture (F / 7.5) and the diameter of the adapted image plane (11mm) are the same, which can realize synchronous imaging at two magnifications and in the same field of view, simplifying system calibration and image fusion, and ensuring measurement consistency.

[0032] In one embodiment, the common front lens group 11 includes, from the object side to the image side, a first lens 1 with positive optical power, a second lens 1 with positive optical power, and a first laminate 1.

[0033] The first emitted beam is a beam transmitted through the beam splitter 12. The first rear lens group includes, from the object side to the image side, a second cemented sheet 2, a third lens 3 with positive optical power, a fourth lens 4 with positive optical power, and a fifth lens 5 with positive optical power.

[0034] The second emitted beam is a beam reflected by the beam splitter 12. The second rear lens group includes, from the object side to the image side, a third cemented sheet 3, a sixth lens 6 with positive optical power, and a seventh lens 7 with positive optical power.

[0035] The system provided in this embodiment effectively corrects spherical and chromatic aberrations through a combination of a positive power lens and a cemented plate using a shared front lens group, providing a high-quality beam for beam splitting. The first rear lens group employs multiple positive lenses and a cemented plate to ensure aberration balance and telecentricity at high magnification. The second rear lens group utilizes a cemented plate and two positive lenses to achieve a compact structure and maintain high resolution at low magnification. The overall design enables both telecentric optical paths to simultaneously achieve clear, low-distortion imaging performance using a shared front lens group.

[0036] In one embodiment, the object plane of the entire optical path structure is on the left, with an initial focusing object distance of 126mm (this focusing object distance is the common object distance for both optical paths, meaning both cameras are focusing on the same object plane); the image plane is on the right, with an image distance of 56mm at 0.436x magnification and 26mm at 0.109x magnification. We define the curvature of the left side of each lens as the object plane curvature, and the curvature of the right side as the image plane curvature, with the curvature facing the object plane being positive and the curvature facing the image plane being negative.

[0037] Therefore, the object side of the first lens 1 is flat, and the image side is convex; the object side of the second lens 2 is convex, and the image side is concave; the first cemented sheet 1 consists of a first lens with positive optical power and a second lens with negative optical power from the object side to the image side, wherein the object side of the first lens is convex and the image side is flat, and the object side of the second lens is flat and the image side is concave; the second cemented sheet 2 consists of a third lens with negative optical power and a fourth lens with positive optical power from the object side to the image side; the third cemented sheet 3 consists of a fifth lens with negative optical power and a sixth lens with positive optical power from the object side to the image side.

[0038] like Figure 5 The figure shows a 0.436x telecentric optical sector diagram provided in this embodiment. The diagram illustrates the set of aberrations generated by the 0.436x telecentric imaging system in different fields of view. The difference between meridional and sagittal aberrations can be seen in each field of view. Since the maximum corresponding image plane is 11mm, the maximum object plane actually used in the above figure is only 25.45mm.

[0039] like Figure 6 As shown, this is a 0.109x telecentric optical sector diagram provided in this embodiment. The diagram shows the set of aberrations generated by the 0.109x telecentric imaging system in different fields of view. The difference between meridional and sagittal aberrations can be seen in each field of view.

[0040] The system provided in this embodiment reduces manufacturing difficulty and efficiently converges the beam by combining the planar and convex surfaces of the first lens. The convex-concave shape of the second lens corrects primary aberrations. The first cemented sheet effectively eliminates chromatic aberration through positive and negative lenses and the planar cemented interface. The second and third cemented sheets adopt negative-positive structures respectively, further balancing spherical aberration and chromatic aberration in the two telecentric optical paths. The overall design enables the dual-magnification system to achieve high image quality, low distortion, and easy manufacturing performance by sharing a common front lens group.

[0041] In one embodiment, the main parameters of the optical system are the curvature, center thickness, aperture, optical spacing between lenses, and material of each lens. Since different materials have different optical properties, mainly different refractive indices and dispersion coefficients, the beam splitter divides the light path into two.

[0042] The curvature profile data for each lens are as follows: The first lens 1 has a flat object plane and a convex spherical image plane with a radius of curvature of -190mm; the second lens 2 has a convex spherical object plane with a radius of curvature of 100mm and a concave spherical image plane with a radius of curvature of 170mm; the first piece of the first cemented sheet 1 has a convex spherical object plane with a radius of curvature of 26mm and a flat image plane; the second piece of the first cemented sheet 1 also has a flat object plane and a concave spherical image plane with a radius of curvature of 10mm; the first piece of the second cemented sheet 2 has a concave spherical object plane with a radius of curvature of -75mm and a convex spherical image plane with a radius of curvature of -11mm; the second piece of the second cemented sheet 2 has a concave spherical object plane with the same curvature as the first piece of the second cemented sheet 2, and its image plane is a convex spherical with a radius of curvature of -35.78mm; the beam splitter 12 is a 90-degree beam splitter; the third lens 3 has a concave spherical object plane with a curvature of... The first object plane of the fourth lens 4 is a concave spherical surface with a radius of curvature of -24.65 mm and an image plane of -13.54 mm. The second object plane of the third cemented sheet 3 is a convex spherical surface with a radius of curvature of -77 mm and an image plane of -50.18 mm. The third object plane of the fourth lens 4 is a convex spherical surface with a radius of curvature of 75 mm and an image plane of -350 mm. The first object plane of the third cemented sheet 3 is a concave spherical surface with a radius of curvature of -9 mm and an image plane of -30 mm. The second object plane of the third cemented sheet 3 is a convex spherical surface with the same curvature as the first image plane of the third cemented sheet 3. The image plane is a convex spherical surface with a radius of curvature of -10 mm. The sixth object plane of the sixth lens 6 is a flat surface with a convex spherical surface and an image plane of -15 mm. The seventh object plane of the seventh lens 7 is a convex spherical surface with a radius of curvature of 30 mm and an image plane. The surface tolerance for all curvatures is 3-5 oz., and the local tolerance is 0.3-0.5 oz. (measured using an interferometer).

[0043] The focal length of the first lens 1 is 310.46 mm; the focal length of the second lens 2 is 236.16 mm; the focal length of the first lens of the first cemented sheet 1 is 40.85 mm, and the focal length of the second lens of the first cemented sheet 1 is -12.98 mm; the focal length of the first lens of the second cemented sheet 2 is 34.54 mm, and the focal length of the second lens of the second cemented sheet 2 is -21.86 mm; the focal length of the third lens 3 is 52.91 mm; the focal length of the fourth lens 4 is 224.21 mm; the focal length of the fifth lens 5 is 121.77 mm; the focal length of the first lens of the third cemented sheet 3 is -8.15 mm, and the focal length of the second lens of the third cemented sheet 3 is 18.54 mm; the focal length of the sixth lens 6 is 27.15 mm; and the focal length of the seventh lens 7 is 35.89 mm. All focal length calculations are performed at the 550 nm wavelength.

[0044] The material specifications for each lens are as follows: All lenses are made of Chengdu Guangming colorless glass and are labeled with Chengdu Guangming's brand name. In order to ensure subsequent industrial production, all brands are currently the recommended brands for mass production.

[0045] The first lens 1 is made of heavy crown glass (h-zk3); the second lens 2 is made of lanthanum crown glass (h-lak53); the first lens of the first cemented sheet 1 is made of fluorine crown glass (h-fk61), and the second lens is made of heavy crown glass (h-zk3a); the beam splitter prism 12 is made of crown glass (h-k9l); the first lens of the second cemented sheet 2 is made of flint glass (h-f4), and the second lens is made of crown glass (h-k51); the third lens 3 is made of heavy crown glass (h-zk11); the fourth lens 4 is made of heavy flint glass (h-zf52gt); the fifth lens 5 is made of heavy lanthanum flint glass (h-zlaf52a); the first lens of the third cemented sheet 3 is made of flint glass (h-f4), and the second lens is made of crown glass (h-k51); the sixth lens 6 is made of heavy flint glass (h-zf52gt); and the seventh lens 7 is made of heavy phosphorus crown glass (h-zpk1a).

[0046] like Figure 7 The diagram shows the field curvature and distortion of the 0.436 telecentric system provided in this embodiment. The left side shows the field curvature (image plane curvature). We can see that different curves represent different wavelengths. The maximum deviation of the image plane curvature is no more than 0.2162 mm, which can be ignored. The right side shows the optical distortion. Generally, the largest distortion occurs at the edge of the entire field of view, and the maximum optical distortion is less than 0.0678%, meeting the design requirements.

[0047] like Figure 8 The diagram shows the field curvature and distortion of the 0.109 telecentric system provided in this embodiment. The left side shows the field curvature (image plane curvature). We can see that different curves represent different wavelengths. The maximum deviation of the image plane curvature is no more than 0.0316 mm, which can be ignored. The right side shows the optical distortion. Generally, the largest distortion occurs at the edge of the entire field of view, and the maximum optical distortion is less than 0.0605%, meeting the design requirements.

[0048] The system provided in this embodiment effectively compensates for spherical aberration, chromatic aberration, and field curvature by precisely defining the curvature radius and other glass materials of each lens and cemented sheet. It achieves high image quality and low distortion in a double-magnification telecentric system while also taking into account the feasibility of processing and assembly.

[0049] In one embodiment, the first lens 1, the second lens 2, and the first cemented plate 1 of the system share two magnifications. The beam splitter is an energy-splitting prism, and the 50:50 splitting ratio refers to the ratio of transmitted to reflected energy. After splitting, the two sets of optical paths are respectively connected to two different sets of optical paths. One path passes through the second cemented plate 2, the third lens 3, the fourth lens 4, and the fifth lens 5 to enter the image plane 1; the other path passes through the third cemented plate 3, the sixth lens 6, and the seventh lens 7 to enter the image plane 2. The total optical length of the optical system (from the curvature center of the first surface of the first lens 1 to the image plane) is 340mm ± 1%. The optical spacing tolerance between the lenses in the shared front lens group 11 is ± 0.02mm, the optical spacing tolerance between the lenses inside the first rear lens group 13 and the second rear lens group 14 is ± 0.02mm, the optical spacing between the first lens 1 and the second lens 2 is 22mm with a tolerance of ± 0.02mm, and the optical spacing between the second lens 2 and the first cemented plate 1 is 104mm with a tolerance of ± 0.02mm. ±0.02mm; the optical distance from the first cemented sheet 1 to the beam splitter 12 is 2mm tolerance ±0.02mm; the system aperture is located at the beam splitting surface of the beam splitter 12, and the optical distance from the aperture to the second cemented sheet 2 is 2mm tolerance ±0.02mm; the optical distance from the second cemented sheet 2 to the third lens 3 is 3mm tolerance ±0.02mm; the optical distance from the third lens 3 to the fourth lens 4 is 11mm tolerance ±0.02mm; the optical distance from the fourth lens 4 to the fifth lens 5 is 71mm tolerance ±0.02mm; the optical distance from the system aperture to the third cemented sheet 3 is 4mm tolerance ±0.02mm; the optical distance from the third cemented sheet 3 to the sixth lens 6 is 0.5mm tolerance ±0.02mm; the optical distance from the sixth lens 6 to the seventh lens 7 is 5mm tolerance ±0.02mm.

[0050] like Figure 9 The figure shows a schematic diagram of the MTF curve (optical modulation transfer function) of the 0.436 telecentric system provided in this embodiment, representing the spatial transfer function of the entire optical system within the operating band. It is a representation of the imaging quality of the entire imaging system, with the horizontal axis representing line pairs / mm and the vertical axis representing frequency. Different lines represent different fields of view and differences in meridion or sagittal. As can be seen from the figure above, at a normalized contrast of 0.3, the number of line pairs is greater than 120 line pairs / mm (because the image size is 11mm, the object size is only referenced to data within 25.45).

[0051] like Figure 10The figure shows a schematic diagram of the MTF (Modulation Transfer Function) curve of the 0.109 telecentric system provided in this embodiment. This represents the spatial transfer function of the entire optical system within the operating wavelength band. It is a representation of the imaging quality of the entire imaging system, with the horizontal axis representing line pairs per millimeter and the vertical axis representing frequency. Different lines represent different fields of view and differences in meridion or sagittal. As can be seen from the figure above, at a normalized contrast of 0.3, the number of line pairs is greater than 130 line pairs per millimeter.

[0052] like Figure 11 The diagram shows the image plane illuminance of the 0.436 telecentric system provided in this embodiment. It illustrates the illumination distribution in different areas of the image plane after light from the 0.436 telecentric system passes through this optical system, demonstrating the attenuation of illuminance in different fields of view. This diagram is an important indicator for evaluating the image plane illuminance of the entire optical system. It can be seen from the diagram that the image illuminance at the edges can reach more than 100% of the illuminance at the center.

[0053] like Figure 12 The diagram shows the image plane illuminance of the 0.109 telecentric system provided in this embodiment. It illustrates the illumination distribution in different areas of the image plane after light from the 0.109 telecentric system passes through this optical system, demonstrating the attenuation of illuminance in different fields of view. This diagram is an important indicator for evaluating the image plane illuminance of the entire optical system. It can be seen from the diagram that the image illuminance at the edges can reach more than 100% of the illuminance at the center.

[0054] like Figure 13 The diagram shown illustrates the circle of confusion distribution of the 0.436x telecentric system provided in this embodiment. It depicts the diffusion of all entrance pupil rays converging onto the image plane in different field-of-view regions of the 0.436x telecentric system. Different curves represent different wavelengths, which is an important way to evaluate the overall imaging characteristics of an optical system. It can be seen that within the designed wavelength range, the geometric radius of the central field-of-view confusion spot can reach within 5.376 micrometers of the Airy disk radius (because the designed image plane is 11mm, only the data for the field-of-view region within 11mm of the image plane are referenced).

[0055] like Figure 14 The diagram shown illustrates the circle of confusion distribution of the 0.109x telecentric system provided in this embodiment. It shows the diffusion of all entrance pupil rays converging onto the image plane in different field-of-view regions of the 0.109x telecentric system. Different curves represent different wavelengths, which is also an important way to evaluate the overall imaging characteristics of an optical system. It can be seen that within the designed wavelength range, the geometric radii of both the center and edge field-of-view confusion spots can reach within 5.375 micrometers of the Airy disk radius.

[0056] The system provided in this embodiment effectively ensures the positional consistency, thermal stability, and imaging clarity of the dual-magnification telecentric optical path after assembly by strictly controlling the total optical length to 340mm±1% and setting a high-precision tolerance of ±0.02mm for the lens spacing inside the shared front lens group and the two rear lens groups. This reduces the debugging difficulty during mass production and ensures that the two optical paths focus synchronously and the magnification relationship is stable.

[0057] Method Implementation Examples According to embodiments of the present invention, an imaging detection method using the above-described double-magnification telecentric optical system is provided, such as... Figure 15 The diagram shown is a flowchart of the imaging detection method provided in this embodiment. The imaging detection method using a double-magnification telecentric optical system according to this embodiment includes the following steps: S1501. Align the optical system with the object being measured so that the object surface is located at the common object working distance.

[0058] S1502, the incident light passes through the common front lens group 11 and is incident on the beam splitter 12.

[0059] S1503 At the beam splitting surface of the beam splitter 12, the system aperture limits the beam aperture and splits the beam into transmitted light and reflected light.

[0060] S1504. Transmitted light enters the first rear lens group 13 and forms a telecentric image at a first magnification on the target surface of the first camera.

[0061] S1505, The reflected light enters the second rear lens group 14 and forms a telecentric image with a second magnification on the target surface of the second camera.

[0062] The telecentric image at the first magnification and the telecentric image at the second magnification have the same field-of-view center coordinates. The first-magnification telecentric optical path and the second-magnification telecentric optical path share a common object-side working distance, and the ratio of the first magnification to the second magnification is 4:1. The aperture number of both the first-magnification telecentric optical path and the second-magnification telecentric optical path is F / 7.5, and the compatible image plane diameter is 11mm.

[0063] The method provided in this embodiment ensures that the object plane is located at a shared object-side working distance, thereby ensuring that both telecentric optical paths simultaneously meet the object-side telecentric condition, avoiding defocus and magnification errors, and achieving synchronous and clear imaging of dual-magnification images. The incident light passes through a shared front lens group, where the beam is efficiently converged and aberration corrected before entering the beam splitter, providing uniform and low-distortion beam quality for subsequent beam splitting, ensuring consistency of object-side information in the two imaging paths. The system aperture at the beam splitter restricts and splits the beam, controlling the direction of the principal ray of the telecentric optical path and simultaneously dividing the beam into transmitted and reflected paths, achieving synchronous acquisition of dual-magnification images without interference. The transmitted light is imaged by the first rear lens, forming a first-magnification telecentric image on the first camera target surface, possessing high magnification and high resolution, suitable for high-precision measurement of fine structures. The reflected light is imaged by the second rear lens, forming a second-magnification telecentric image on the second camera target surface, with a smaller magnification and larger field of view, balancing overall contour observation and dual-magnification image fusion positioning, and the center coordinates of the two images' fields of view are the same, facilitating direct comparison.

[0064] The embodiments of the present invention are method embodiments corresponding to the above system embodiments. The specific operations of each Zhuzhou process can be understood by referring to the description of the system embodiments, and will not be repeated here.

[0065] like Figure 16 As shown, the present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it implements the imaging detection method of the double-magnification telecentric optical system in the above embodiments, or when the computer program is executed by a processor, it implements the imaging detection method of the double-magnification telecentric optical system in the above embodiments.

[0066] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0067] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for apparatus or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The apparatus and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. Components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. 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 or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and the contents not described in detail in the specification of the present invention are known to those skilled in the art.

Claims

1. A double-magnification telecentric optical system, characterized in that, It includes a common front lens group, a beam splitter, a first rear lens group, and a second rear lens group arranged sequentially along the optical path: A beam splitter is used to separate an incident beam that has passed through the common front lens group into a first outgoing beam and a second outgoing beam, with the optical axes of the two outgoing beams intersecting perpendicularly at the beam splitting surface of the beam splitter. The first rear lens group is disposed in the optical path of the first emitted beam, forming a first magnification telecentric optical path; The second rear lens group is disposed in the optical path of the second emitted beam, forming a second magnification telecentric optical path; The system aperture of the optical system is disposed on the beam-splitting surface.

2. The double-magnification telecentric optical system as described in claim 1, characterized in that, The first-magnification telecentric optical path and the second-magnification telecentric optical path share a common object-side working distance, and the ratio of the first magnification to the second magnification is 4:1; Both the first and second magnification telecentric optical paths have an aperture of F / 7.5, and can be adapted to an image plane diameter of 11mm.

3. The double-magnification telecentric optical system as described in claim 1, characterized in that, The common front lens group, from the object side to the image side, includes a first lens with positive optical power, a second lens with positive optical power, and a first cemented sheet in sequence. The first emitted beam is a beam transmitted through the beam splitter prism, and the first rear lens group includes, from the object side to the image side, a second cemented sheet, a third lens with positive optical power, a fourth lens with positive optical power, and a fifth lens with positive optical power. The second emitted beam is a beam reflected by the beam splitter prism, and the second rear lens group includes, from the object side to the image side, a third cemented sheet, a sixth lens with positive optical power, and a seventh lens with positive optical power.

4. The double-magnification telecentric optical system as described in claim 3, characterized in that, The object-side surface of the first lens is flat, and the image-side surface is convex. The object-side surface of the second lens is convex, and the image-side surface is concave. The first adhesive sheet consists of a first lens with positive optical power and a second lens with negative optical power, arranged sequentially from the object side to the image side. The object side of the first lens is convex and the image side is flat, while the object side of the second lens is flat and the image side is concave. The second laminate consists of a third lens with negative optical power and a fourth lens with positive optical power, arranged sequentially from the object side to the image side. The third laminate consists of a fifth lens with negative optical power and a sixth lens with positive optical power, arranged sequentially from the object side to the image side.

5. The double-magnification telecentric optical system as described in claim 3 or 4, characterized in that, The radius of curvature and material of the lens and the lamination meet the following conditions: The radius of curvature of the side surface of the first lens is -190mm ± 5%; The second lens has an object side curvature radius of 100mm ± 5% and an image side curvature radius of 170mm ± 5%. The first lens of the first laminate has an object-side curvature radius of 26mm ± 5%, and the second lens has an image-side curvature radius of 10mm ± 5%. The first lens is made of H-ZK3 material, and the second lens is made of H-LAK53 material; The first lens of the first laminate is made of H-FK61 material, and the second lens is made of H-ZK3A material.

6. The double-magnification telecentric optical system as described in claim 1, characterized in that, The total optical length of the optical system is 340mm ± 1%, wherein the optical spacing tolerance between the lenses in the common front lens group is ± 0.02mm, and the optical spacing tolerance between the lenses in the first rear lens group and the second rear lens group is ± 0.02mm.

7. An imaging detection method using the double-magnification telecentric optical system according to any one of claims 1 to 6, characterized in that, Includes the following steps: Align the optical system with the object being measured so that the object surface is located at the common object-side working distance; The incident light passes sequentially through the shared front lens group and is then incident on the beam splitter. At the beam-splitting surface of the beam-splitting prism, the system aperture limits the beam aperture and splits the beam into transmitted light and reflected light; Transmitted light enters the first rear lens group and forms a telecentric image at a first magnification on the target surface of the first camera; The reflected light enters the second rear lens group and forms a telecentric image at a second magnification on the target surface of the second camera; The telecentric image at the first magnification and the telecentric image at the second magnification have the same field-of-view center coordinates.

8. The imaging detection method as described in claim 7, characterized in that, The first-magnification telecentric optical path and the second-magnification telecentric optical path share a common object-side working distance, and the ratio of the first magnification to the second magnification is 4:1; Both the first and second magnification telecentric optical paths have an aperture of F / 7.5, and can be adapted to an image plane diameter of 11mm.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the imaging detection method as described in any one of claims 7 to 8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the imaging detection method as described in any one of claims 7 to 8.

Images