Large-breadth flange type telecentric field lens

Abstract

The utility model relates to the technical field of large-breadth infrared telecentric lens scanning, and discloses a large-breadth flange type telecentric field lens, and the main body of the field lens comprises a lens barrel and five lenses which are sequentially arranged along the light beam propagation direction. The first lens is of a biconcave structure, and the focal length is negative. The second lens is of a meniscus structure, and the focal length is positive. The third lens is meniscus-shaped, and the focal length is positive; the fourth lens is in a large-aperture plano-convex shape, and the focal length is positive; the fifth lens is a protective window lens and is in a large-aperture biplane shape, and the focal length of the fifth lens is infinite. And each lens is fixed in the lens cone through a threaded pressing ring. The focal length of the field lens main body is F420, the processing breadth is 200 * 200 mm, the central field angle is less than 0.5 degree, and the edge field angle is less than 3 degrees. Through reasonable optical design, combination of long focal length and large breadth processing is realized, the problems that an existing field lens is short in applicable focal length range and can only be used for small breadth processing are solved, and applicability and flexibility of the field lens in an industrial processing scene are effectively improved.

Description

A large-format flange-type telecentric field mirror Technical Field

[0001] This utility model relates to the field of large-format infrared telecentric lens scanning technology, and in particular to a large-format flange-type telecentric field lens. Background Technology

[0002] With the development of laser processing application technology, the market demand for telecentric field lenses is increasing. The advantage of telecentric scanning field lenses lies in the perpendicularity of light rays, which can effectively solve the problem of hole taper angle in laser drilling. However, most of the telecentric field lens products currently on the market are short focal length field lenses with an aperture of F200 or less, which can only be used for small-area processing within a range of 100x100mm.

[0003] For example, a telecentric field lens with ultra-long focal depth and large scanning area disclosed in Chinese announcement number CN208937802U includes an entrance pupil surface and a laser field lens working surface. A first lens, a second lens, a third lens, and a window are arranged sequentially between the entrance pupil surface and the laser field lens working surface. The first lens has a negative focal length, the second lens has a positive focal length, and the third lens has a positive focal length. The focal length of the entire field lens is 150-170 mm, the total optical length of the field lens is 110-130 mm, the focal depth is greater than or equal to 3 mm, the wavelength used is 1064 nm, and the scanning area is greater than 80*80 mm.

[0004] The above-mentioned solution has a short applicable focal length range and can only be used for small-format processing. Therefore, a new solution is needed to solve these problems. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a large-format flange-type telecentric field mirror.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a large-format flange-type telecentric field lens, comprising a field lens body, the field lens body including a lens barrel and a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the beam propagation direction within the lens barrel; the first lens is a biconcave structure with a negative focal length; the second lens is a meniscus structure with a positive focal length; the third lens is a meniscus shape with a positive focal length; the fourth lens is a large-aperture plano-convex shape with a positive focal length; the fifth lens is a protective window lens, a large-aperture biplanar shape with an infinite focal length; the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all fixed by threaded pressure rings that are threadedly connected to the lens barrel; the focal length of the field lens body is F420, the processing area is 200×200mm, the central field of view is less than 0.5°, and the edge field of view is less than 3°.

[0007] In a preferred embodiment of this utility model, the front surface curvature radius R1 of the first lens is -97.5mm, the rear surface curvature radius R2 is 188.6mm, the center thickness is 3mm, and the focal length is -142.4mm.

[0008] In a preferred embodiment of this invention, the front surface curvature radius R3 of the second lens is -295mm, the rear surface curvature radius R4 is -97.2mm, the center thickness is 6.5mm, and the focal length is 318mm.

[0009] In a preferred embodiment of this utility model, the front surface curvature radius R5 of the third lens is -404.2mm, the rear surface curvature radius R6 is -139mm, the center thickness is 30mm, and the focal length is 400mm.

[0010] In a preferred embodiment of this utility model, the front surface curvature radius R7 of the fourth lens is 515mm, the rear surface curvature radius R8 is infinite, the center thickness is 14mm, and the focal length is 1145.5mm.

[0011] In a preferred embodiment of this utility model, the front and rear surfaces of the protective window mirror have infinite radii of curvature, and the center thickness is 3mm.

[0012] In a preferred embodiment of this utility model, the first lens and the second lens are placed together and fixed by the same threaded retaining ring; the threaded retaining ring used to fix the first lens, the second lens and the fifth lens is made of polyurethane; the threaded retaining ring used to fix the third lens and the fourth lens is made of copper.

[0013] In a preferred embodiment of this utility model, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all made of quartz.

[0014] In a preferred embodiment of this utility model, the outer shell of the lens barrel adopts a flange structure, and a plurality of evenly distributed flange holes are provided on the outer side of the lens barrel for connection with the galvanometer.

[0015] In a preferred embodiment of this utility model, an O-ring is provided on the inner side of each threaded pressure ring.

[0016] This utility model solves the defects existing in the background technology, and has the following beneficial effects:

[0017] This application achieves a focal length of F420 through reasonable optical design, and achieves telecentric drilling processing with a center angle of less than 0.5 degrees and an edge angle of less than 3 degrees for a 200x200mm lens. This effectively solves the problem that existing field lenses have a short applicable focal length range and can only be used for small-format processing. At the same time, in terms of mechanical structure, in response to the problem of large lens diameter and heavy overall lens weight, a flange structure fixing method is adopted, which is different from the traditional threaded fixing structure. The lens barrel uses a threaded pressure ring with an O-ring seal, which effectively achieves dustproof sealing and prevents lens loosening. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 is a schematic diagram of the structure of the flange-type telecentric field mirror of this utility model;

[0020] Figure 2 is a light tracing diagram of an embodiment of the telecentric field mirror of this utility model;

[0021] Figure 3 is a dot diagram of an embodiment of the telecentric field mirror of this utility model;

[0022] Figure 4 is a field curvature / distortion distribution diagram of an embodiment of the telecentric field mirror of this utility model;

[0023] Figure 5 shows the optical transfer function of the telecentric field mirror of this invention;

[0024] In the diagram: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Lens barrel; 7. Threaded pressure ring one; 8. Threaded pressure ring two; 9. Threaded pressure ring three; 10. Flange hole. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0026] Example 1:

[0027] As shown in Figure 1, this embodiment provides a large-format flange-type telecentric field lens, including a field lens body. The field lens body consists of a lens barrel 6 and five lenses arranged sequentially along the beam propagation direction, including:

[0028] First lens 1: It adopts a biconcave structure with a negative focal length, specifically f1 = -142.4mm. Stable quartz was chosen as the material, with a front surface radius of curvature R1 = -97.5mm, a rear surface radius of curvature R2 = 188.6mm, and a center thickness of only 3mm. This design allows the first lens 1 to perform preliminary convergence control of light, laying the foundation for beam shaping by subsequent lenses.

[0029] Second lens 2: It has a meniscus structure, a positive focal length of f2 = 318mm, and is also made of quartz. The front surface curvature radius R3 = -295mm, the rear surface curvature radius R4 = -97.2mm, and the center thickness is 6.5mm. The meniscus structure optimizes the propagation direction and spot shape of the light beam during the convergence process, further improving the imaging quality of the optical system.

[0030] The third lens 3 is a large-aperture meniscus structure with a positive focal length of f3 = 400mm. It is made of quartz, with a front surface radius of curvature R5 = -404.2mm, a rear surface radius of curvature R6 = -139mm, and a center thickness of 30mm. The large-aperture design can accommodate more light and increase the amount of light transmitted, which is extremely important for ensuring the uniformity of illumination when the field lens is processed in a large format. At the same time, the setting of its focal length and radius of curvature helps to further refine the beam, making the light more regular and orderly during propagation.

[0031] The fourth lens (4) is a large-aperture plano-convex structure with a positive focal length of f4 = 1145.5 mm, made of quartz. The front surface has a radius of curvature of R7 = 515 mm, the rear surface has a radius of curvature of R8 = ∞, and a center thickness of 14 mm. The plano-convex structure gives this lens a unique advantage in light convergence, allowing for final fine adjustments to the light rays after they have been shaped by the preceding lenses, ensuring that the light converges ideally near the focal point. Its large aperture also helps maintain consistent optical performance across a large format.

[0032] The fifth lens 5 is designed to protect the window lens. It has a double-flat structure, an infinite focal length, and is made of quartz. The front and rear surfaces have infinite radii of curvature, and the center thickness is 3mm. This design plays a protective role, effectively preventing external impurities, dust, and debris generated during processing from entering the lens barrel 6 and causing contamination or damage to other precision lenses. This ensures the stability and reliability of the entire optical system and extends the service life of the field lens.

[0033] Furthermore, the first lens 1 and the second lens 2 are fixed together by a threaded retainer 7 made of polyurethane material. An O-ring is provided on the inner side of the threaded retainer 7. This sealing design can effectively prevent dust and other foreign objects from entering the lens barrel 6, ensuring that the first two lenses are always in a clean optical environment during long-term use, maintaining the stability and consistency of their optical performance. Moreover, the threaded retainer made of polyurethane material has sufficient mechanical strength to fix the lens, and also has a certain degree of elasticity, which can buffer the impact of external vibrations on the lens and protect the optical accuracy of the lens.

[0034] The third lens 3 and the fourth lens 4 are large-aperture lenses, and therefore heavy. They are fixed with copper threaded retaining rings 8. Copper has excellent elasticity and mechanical strength, which can provide a stable and reliable fixing force for the large-aperture third and fourth lenses 4. This ensures that they can maintain good optical position and posture stability even in complex industrial environments, such as when affected by vibration, temperature changes and other factors. The design of the threaded retaining ring can also absorb and disperse stress to a certain extent, avoiding damage to the lens due to excessive tightening. At the same time, it also helps to compensate for the small dimensional deviations that may occur during the manufacturing and installation of the lens, ensuring the overall assembly accuracy of the optical system.

[0035] The fifth lens 5 is fixed by a threaded retaining ring 3 9 with an O-ring. The cooperation between the O-ring and the threaded retaining ring 3 9 not only achieves a firm fixation of the fifth lens 5, but also further enhances its sealing and dustproof function. In industrial processing scenarios, good sealing can protect the optical components inside the field lens from the influence of the external environment, thereby effectively reducing maintenance costs and improving the operating efficiency and reliability of the field lens.

[0036] Furthermore, the lens barrel 6 adopts a flange structure with six evenly distributed flange holes 10 on the outer side, each with a diameter of 8mm, for mechanical connection with the galvanometer system. This flange design enhances the overall rigidity of the lens, making it suitable for vibration and shock in industrial environments. It not only enables a quick, convenient, and stable mechanical connection with the galvanometer but also ensures the installation accuracy and stability of the field lens during use. In addition, the flange structure facilitates the integration and docking of the field lens with other related equipment or components, improving the modularity and flexibility of the entire processing system, which is beneficial for system design, installation, commissioning, and subsequent maintenance and upgrades.

[0037] As shown in the ray tracing diagram in Figure 2, the field lens has a total focal length of F420 and an exit pupil located at infinity on the image side. This optical characteristic allows the field lens to achieve a large depth of field during use, maintaining good image sharpness on workpiece surfaces at different heights in large-format processing. The principal ray is perpendicularly incident on the processing surface at all field of view angles, with a central field of view angle of less than 0.5° and an edge field of view angle of less than 3°. This design effectively ensures minimal geometric distortion and accurate spot position across the entire field of view, providing strong optical support for high-precision processing. In practical processing applications, such as PCB drilling and precision cutting, precise spot positioning and low distortion characteristics can significantly improve processing accuracy and quality, reduce processing errors, and increase production efficiency and product yield.

[0038] As shown in Figures 3 and 4, the dot plot and field distortion diagrams in Figure 3 visually demonstrate the optical imaging quality of the field lens. The light spot distribution is uniform across the entire field of view, indicating that the field lens can distribute light evenly on the processing plane, avoiding inconsistent processing caused by uneven light spots.

[0039] Figure 5 shows the optical transfer function (OTF) curve, an important indicator for evaluating the imaging quality of an optical system. The OTF is a complex function describing the imaging quality of an optical system, comprising the modulation transfer function (MTF) and the phase transfer function (PTF). The OTF magnitude represents the optical system's ability to transmit modulation contrast for different spatial frequency components. Spatial frequency is a physical quantity used to describe the density of bright and dark fringes on an object or image, typically measured in line pairs per millimeter (lp / mm). It reflects the rate of spatial change of an object; the higher the spatial frequency, the faster the changes in object details, enabling clearer resolution of fine structures and features on the workpiece, meeting the requirements of high-resolution processing. As the spatial frequency increases, the OTF magnitude generally decreases. This is because optical systems are limited by various factors when transmitting high-frequency detail information (such as subtle textures on an object's surface, small edges, etc.), including aberrations of optical elements (such as spherical aberration, chromatic aberration, coma, etc.), diffraction effects, and absorption by optical materials. As shown in the optical transfer function diagram in Figure 5, the large-format flange-type telecentric field lens provided in this embodiment maintains a high OTF modulus value over a wide spatial frequency range, enabling better rendering of image details. In practical applications, such as drilling dense circuit holes and cutting fine patterns on PCBs, this high-resolution characteristic ensures that the processed graphics have clear edges and delicate lines, improving the overall quality and performance of the product.

[0040] The large-format flange-type telecentric field lens provided in this embodiment, through the combination of five lenses, a reasonable fixing method, and an excellent lens barrel structure, achieves a series of superior optical performances, including high resolution, low distortion, and uniform spot distribution, within a large-format processing range of 200×200mm. It effectively solves the problems of limited format and insufficient compatibility with long focal lengths in existing technologies, providing an efficient, stable, and reliable optical solution for industrial scenarios such as PCB drilling and precision cutting, and possesses broad market application prospects and significant technological innovation value.

[0041] Based on the preferred embodiments of this utility model described above, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A large-format flange-type telecentric field mirror, comprising a field mirror body, characterized in that, The field lens body includes a lens barrel (6) and a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), and a fifth lens (5) arranged sequentially along the beam propagation direction inside the lens barrel (6); the first lens (1) is a biconcave structure with a negative focal length; the second lens (2) is a meniscus structure with a positive focal length; the third lens (3) is a meniscus shape with a positive focal length; the fourth lens (4) is a large-aperture plano-convex shape with a positive focal length; the fifth lens (5) is a protective window lens with a large-aperture biplanar shape and an infinite focal length; the first lens (1), the second lens (2), the third lens (3), the fourth lens (4), and the fifth lens (5) are all fixed by threaded pressure rings that are threadedly connected to the lens barrel (6); the focal length of the field lens body is F420, the processing area is 200×200mm, the central field of view is less than 0.5°, and the edge field of view is less than 3°.

2. The large-format flange-type telecentric field mirror according to claim 1, characterized in that: The first lens (1) has a front surface curvature radius R1 of -97.5mm, a rear surface curvature radius R2 of 188.6mm, a center thickness of 3mm, and a focal length of -142.4mm.

3. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The second lens (2) has a front surface curvature radius R3 of -295mm, a rear surface curvature radius R4 of -97.2mm, a center thickness of 6.5mm, and a focal length of 318mm.

4. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The third lens (3) has a front surface curvature radius R5 of -404.2mm, a rear surface curvature radius R6 of -139mm, a center thickness of 30mm, and a focal length of 400mm.

5. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The fourth lens (4) has a front surface curvature radius R7 of 515mm, a rear surface curvature radius R8 of infinity, a center thickness of 14mm, and a focal length of 1145.5mm.

6. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The protective window mirror has infinite radii of curvature on both its front and rear surfaces, and a center thickness of 3 mm.

7. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The first lens (1) and the second lens (2) are placed together and fixed by the same threaded retainer; the threaded retainer used to fix the first lens (1), the second lens (2) and the fifth lens (5) is made of polyurethane; the threaded retainer used to fix the third lens (3) and the fourth lens (4) is made of copper.

8. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The first lens (1), the second lens (2), the third lens (3), the fourth lens (4) and the fifth lens (5) are all made of quartz.

9. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: The outer shell of the lens barrel (6) adopts a flange structure, and several evenly distributed flange holes (10) are provided on the outer side of the lens barrel (6) for connecting with the galvanometer.

10. A large-format flange-type telecentric field mirror according to claim 1, characterized in that: Each threaded pressure ring has an O-ring on its inner side.

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