Wide-spectrum zoom optical imaging system for welding seam detection

Abstract

The utility model relates to the technical field of optics, in particular to a wide-spectrum zoom optical imaging system for welding seam detection, which comprises a first fixing group, a zoom group, a compensation group, a second fixing group and a filter disc group which are sequentially arranged along a first direction. The first fixed group is fixedly arranged and is used for correcting distortion and converging light beams; the zoom group is movably arranged along a first direction and is used for correcting spherical aberration; the compensation group is movably arranged along a first direction and is used for correcting wide-spectrum chromatic aberration and converging a target light beam; the compensation group comprises an aperture diaphragm, a first negative lens, a first positive lens and a second negative lens which are sequentially arranged at intervals, and the light-out surface of the first negative lens and the light-in surface of the first positive lens are diffraction surfaces; the second fixed group is fixedly arranged and is used for correcting field curvature and converging the target light beam to the filter disc group; the filter disc group is fixedly arranged and used for filtering the target light beam to realize imaging. Therefore, wide-spectrum, high-quality and high-resolution imaging is ensured, the zoom range is large, and the structure is simple and compact.

Description

Technical Field

[0001] This utility model relates to the field of optical technology, and in particular to a broadband zoom optical imaging system for weld inspection. Background Technology

[0002] Weld inspection is a crucial step in evaluating weld quality. With technological advancements, zoom optical imaging systems have gradually replaced visual inspection as the primary method for weld inspection. Zoom optical imaging systems can change the focal length to acquire clear images of both the overall weld and specific areas, thereby detecting weld defects.

[0003] In existing technologies, zoom optical imaging systems struggle to achieve both high-resolution, high-quality imaging across a wide spectral range and a compact structure with a wide zoom range. Utility Model Content

[0004] The broadband zoom optical imaging system for weld inspection provided by this embodiment of the invention at least solves the problem that zoom optical imaging systems, while ensuring high-resolution and high-quality imaging across a wide spectrum, struggle to simultaneously achieve a compact structure and a large zoom range. Thus, it guarantees high-quality, high-resolution imaging across a wide spectrum, a large zoom range, and a simple and compact structure.

[0005] This invention provides a broadband zoom optical imaging system for weld inspection, comprising: a first fixed group, a zoom group, a compensation group, a second fixed group, and a filter group arranged sequentially along a first direction; the first fixed group is fixedly arranged and is used to correct distortion and converge the target beam to the zoom group; the zoom group is movably arranged along the first direction and is used to correct spherical aberration; the compensation group is movably arranged along the first direction and is used to correct broadband chromatic aberration and converge the target beam to the second fixed group; wherein, the compensation group includes an aperture stop, a first negative lens, a first positive lens, and a second negative lens arranged at intervals along the arrangement direction of the zoom group and the second fixed group, the light-emitting surface of the first negative lens and the light-incident surface of the first positive lens are both set as diffraction surfaces; the second fixed group is fixedly arranged and is used to correct field curvature and converge the target beam to the filter group; the filter group is fixedly arranged and is used to filter the target beam to achieve imaging.

[0006] In one embodiment of this invention, the radius of curvature of the incident surface of the first negative lens is... Satisfies the relation 12.5mm≤ ≤13.3mm; the radius of curvature of the light-emitting surface of the first negative lens Satisfies the relation, 9.2mm≤ ≤9.6mm; Radius of curvature of the incident surface of the first positive lens Satisfies the relation, 9.2mm≤ ≤9.6mm; Radius of curvature of the light-emitting surface of the first positive lens The relation is satisfied: -21.2mm ≤ ≤-20.1mm; Radius of curvature of the incident surface of the second negative lens The relationship is satisfied: -10.8mm ≤ ≤-9.9mm; Radius of curvature of the light-emitting surface of the second negative lens Satisfies the relation, 87.1mm≤ ≤87.9mm.

[0007] In one embodiment of this invention, the phase distribution function of the light-emitting surface of the first negative lens Satisfying the relation:

[0008] ,

[0009] In the formula, The phase coefficient of the light-emitting surface of the first negative lens; Let be the phase coordinates of the light-emitting surface of the first negative lens. , The phase distribution function coordinate system Axis coordinates The phase distribution function coordinate system Axis coordinates; wherein, the phase distribution function The coordinate system is a Cartesian rectangular coordinate system with the intersection of the light-emitting surface of the first negative lens and the optical axis of the target as the origin. The incident direction of the target beam is the phase distribution function. coordinate system The positive direction of the axis; the phase coefficient of the light-emitting surface of the first negative lens satisfies the following relationship. , , , , .

[0010] In one embodiment of this invention, the phase distribution function of the incident surface of the first positive lens Satisfying the relation:

[0011] ,

[0012] In the formula, Let be the phase coefficient of the incident surface of the first positive lens. Let be the phase coordinates of the incident surface of the first positive lens. , The phase distribution function coordinate system Axis coordinates The phase distribution function coordinate system Axis coordinates; wherein, the phase distribution function The coordinate system is a Cartesian rectangular coordinate system with the intersection of the incident surface of the first positive lens and the optical axis of the target beam as the origin. The incident direction of the target beam is the phase distribution function. coordinate system The positive direction of the axis; the phase coefficient of the incident surface of the first positive lens satisfies the following relationship. , , , , .

[0013] In one embodiment of this utility model, the distance between the aperture stop and the first negative lens along the first direction is... Satisfy the relation, .

[0014] In one embodiment of this invention, the Abbe number of the first negative lens is set to be less than the Abbe number of the first positive lens.

[0015] In one embodiment of this utility model, the first fixing group includes a second positive lens, a third negative lens, and a fourth negative lens arranged sequentially at intervals along the arrangement direction of the first fixing group and the zoom group; the radius of curvature of the incident surface of the second positive lens is... Satisfy the relation, The radius of curvature of the light-emitting surface of the second positive lens Satisfy the relation, The radius of curvature of the incident surface of the third negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the third negative lens Satisfy the relation, The radius of curvature of the incident surface of the fourth negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the fourth negative lens Satisfy the relation, .

[0016] In one embodiment of this utility model, the zoom group includes a fifth negative lens, a sixth negative lens, a seventh negative lens, and a third positive lens arranged sequentially at intervals along the arrangement direction of the first fixed group and the compensation group; the radius of curvature of the incident surface of the fifth negative lens is... Satisfy the relation, The radius of curvature of the light-emitting surface of the fifth negative lens Satisfy the relation, The radius of curvature of the incident surface of the sixth negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the sixth negative lens Satisfy the relation, The radius of curvature of the incident surface of the seventh negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the seventh negative lens Satisfy the relation, The radius of curvature of the incident surface of the third positive lens Satisfy the relation, The radius of curvature of the light-emitting surface of the third positive lens Satisfy the relation, .

[0017] In one embodiment of this utility model, the second fixing group includes an eighth negative lens and a fourth positive lens arranged sequentially at intervals along the arrangement direction of the compensation group and the filter group; the radius of curvature of the incident surface of the eighth negative lens is... Satisfy the relation, The radius of curvature of the light-emitting surface of the eighth negative lens Satisfy the relation, The radius of curvature of the incident surface of the fourth positive lens Satisfy the relation, The radius of curvature of the light-emitting surface of the fourth positive lens Satisfy the relation, .

[0018] In one embodiment of this utility model, the filter group includes a long-wavelength cutoff filter and a short-wavelength cutoff filter; the cutoff band of the long-wavelength cutoff filter... Satisfy the relation, The cutoff band of the short-wave cutoff filter Satisfy the relation, .

[0019] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial effects:

[0020] This utility model provides a broadband zoom optical imaging system for weld inspection. A front fixed group converges the target beam and corrects system distortion, while a zoom group corrects spherical aberration, improving imaging quality and resolution. The coordinated movement of the zoom and compensation groups achieves a wide zoom range. The inclusion of a first and second diffraction surface in the compensation group reduces the overall system size and mass; simultaneously, it utilizes a double-layer diffraction optical element to correct broadband chromatic aberration and off-axis aberration, increasing broadband coverage, improving diffraction efficiency, and enhancing broadband imaging quality and resolution. The second fixed group corrects the field curvature of the target beam converged by the compensation group, further improving imaging quality and resolution. A filter group filters out clutter, ensuring image quality. This broadband zoom optical imaging system achieves both high-quality, high-resolution broadband imaging and a compact structure. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 This is a schematic diagram of the short focal length state of the broadband zoom optical imaging system according to an embodiment of this utility model.

[0023] Figure 2 This is a schematic diagram of the focal state in a broadband zoom optical imaging system according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the structure of the broadband zoom optical imaging system in the long focal length state according to an embodiment of this utility model.

[0025] Figure 4 This is a ray tracing point diagram of the visible light band of a broadband zoom optical imaging system according to an embodiment of this utility model.

[0026] Figure 5 This is a modulation transfer function curve on the image plane corresponding to the short focal length state of the visible light band in an embodiment of this utility model.

[0027] Figure 6 This is a modulation transfer function curve on the image plane corresponding to the visible light band in the mid-focus state of an embodiment of this utility model.

[0028] Figure 7This is a modulation transfer function curve on the image plane corresponding to the visible light band in the telephoto state of an embodiment of this utility model.

[0029] Figure 8 This is a distortion curve diagram of the visible light band corresponding to the image plane in the short focal length state of an embodiment of this utility model.

[0030] Figure 9 This is a distortion curve diagram of the visible light band corresponding to the image plane in the mid-focus state of an embodiment of this utility model.

[0031] Figure 10 This is a distortion curve diagram of the visible light band corresponding to the image plane in the telephoto state of an embodiment of this utility model.

[0032] Figure 11 This is a ray tracing point diagram of the near-infrared band of a broadband zoom optical imaging system according to an embodiment of this utility model.

[0033] Figure 12 This is a modulation transfer function curve on the image plane corresponding to the near-infrared band in the short focal length state of an embodiment of this utility model.

[0034] Figure 13 This is a modulation transfer function curve on the image plane corresponding to the near-infrared band in the mid-focus state of an embodiment of this utility model.

[0035] Figure 14 This is a modulation transfer function curve on the image plane corresponding to the near-infrared band in the telephoto state of an embodiment of this utility model.

[0036] Figure 15 This is a distortion curve diagram of the near-infrared band corresponding to the image plane in the short focal length state of an embodiment of this utility model.

[0037] Figure 16 This is a distortion curve diagram of the near-infrared band corresponding to the image plane in the mid-focus state of an embodiment of this utility model.

[0038] Figure 17 This is a distortion curve diagram of the near-infrared band corresponding to the image plane in the long focal length state of an embodiment of this utility model.

[0039] Figure 18 This is the energy concentration curve on the image plane corresponding to the short focal length state of an embodiment of this utility model.

[0040] Figure 19 This is the energy concentration curve on the image plane corresponding to the central focal state in an embodiment of this utility model.

[0041] Figure 20 This is the energy concentration curve on the image plane corresponding to the telephoto state in an embodiment of this utility model.

[0042] Figure 21 This is a diffraction efficiency curve of the first and second diffraction surfaces according to an embodiment of the present invention.

[0043] Figure 22 This is a cam curve diagram of a broadband zoom optical imaging system according to an embodiment of the present invention.

[0044] The above-mentioned figures include the following reference numerals: D1, first direction; 10, first fixed group; 11, second positive lens; 12, third negative lens; 13, fourth negative lens; 20, zoom group; 21, fifth negative lens; 22, sixth negative lens; 23, seventh negative lens; 24, third positive lens; 30, compensation group; 31, aperture stop; 32, first negative lens; 321, first diffraction surface; 33, first positive lens; 331, second diffraction surface; 34, second negative lens; 40, second fixed group; 41, eighth negative lens; 42, fourth positive lens; 50, filter group; 51, long-wavelength cutoff filter; 52, short-wavelength cutoff filter; 60, imaging plane; 70, target optical axis. Detailed Implementation

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0048] It should be noted that with the development of technology, welding is becoming increasingly complex, and the control of weld quality is becoming more and more stringent. Weld inspection not only requires clearly identifying whether the surface is continuous, smooth, and free of excessive shine, and whether there are defects such as leakage, false welding, or adhesion, but also requires determining whether the weld positioning is correct. At the same time, it is necessary to capture a variety of key information about the inside and surface of the weld in complex environments.

[0049] Traditional inspection methods involve manual visual inspection, which is susceptible to subjective human error and prone to significant inaccuracies. With the development of industrial automation, machine vision inspection is gradually replacing visual inspection. Image acquisition during weld inspection typically employs a combination of optical imaging systems and light sources, along with software for automatic recognition and detection, thus improving the efficiency and quality of weld inspection.

[0050] To achieve clear imaging of key features such as the molten pool and weld formation, high-resolution zoom lenses are required for different working distances and weld sizes. Zoom lenses utilize the visible light band to clearly observe visible defects such as weld surface morphology, color changes, and oxide layers; and utilize the near-infrared band to monitor the molten pool temperature distribution and heat-affected zone changes in real time. Zoom lenses also allow for continuous adjustment of the focal length, enabling not only comprehensive inspection of the entire weld surface but also magnified inspection of specific weld areas.

[0051] The paper "Design of a Wide-Spectrum Zoom Optical Imaging System" ([D]. Xi'an University of Technology, 2024) designs a wide-spectrum 5x zoom imaging system. Based on the aberration theory of optical imaging systems, Gaussian optical calculations are performed to obtain the initial structure of the wide-spectrum zoom optical imaging system. Through iterative optimization, a wide-spectrum zoom optical imaging system with a wavelength range of 0.4μm to 1.7μm and a zoom range of 40mm to 200mm is designed.

[0052] However, the structure of this wide-spectrum zoom optical imaging system is relatively complex and its total length is too long, reaching 220mm, which has many limitations such as volume and weight; on the other hand, the short focal length of the system is about 40mm, resulting in a long working distance, making it difficult to use for close-range weld identification.

[0053] This indicates that, in related technologies, zoom optical imaging systems, while ensuring high-resolution and high-quality imaging across a wide spectral range, struggle to simultaneously achieve both a compact structure and a wide zoom range.

[0054] To solve the above technical problems, refer to Figures 1 to 3 As shown, this utility model provides a broadband zoom optical imaging system for weld inspection, comprising: a first fixed group 10, a zoom group 20, a compensation group 30, a second fixed group 40, and a filter group 50 arranged sequentially along a first direction D1.

[0055] Preferably, all components are aligned with the target optical axis 70. It is understood that the target optical axis 70 is a common axis passing through the centers of all core optical elements and the center of curvature. Preferably, the first direction D1 is parallel to the axial direction of the target optical axis 70.

[0056] When inspecting welds, a light source is typically used to illuminate the weld. The light beam reflected from the weld serves as the target beam and is transmitted to an optical imaging system. The system processes the light and creates an image, thus enabling the inspection of the weld.

[0057] Since the first fixed group 10 does not participate in the zoom process, but is only used to correct distortion and converge the target beam to the zoom group 20, the first fixed group 10 is fixed.

[0058] When the target beam enters the first fixed group 10, the lenses of the first fixed group 10 converge the diverging target beam into a convergent target beam through refraction, thereby matching the light transmission requirements of the subsequent zoom group 20 and transmitting it into the zoom group 20. In this way, the image quality and resolution can be improved.

[0059] The first fixed group 10 precisely controls the refraction angle of the edge field-of-view rays of the target beam, making the magnification of the edge field-of-view rays nearly identical to that of the central field-of-view rays, thereby canceling out the resulting distortion. The distortion occurs because the light rays in the edge field of view of the target beam are excessively or insufficiently refracted in various components, causing their magnification to differ from that of the central field of view, resulting in image distortion. The central field of view is the core region of the field of view, and the edge field of view is the outer region of the field of view; the field of view is the observable area.

[0060] Furthermore, because the first fixed group 10 is a fixed setting, the correction effect can stably cover the entire focal length range, ensuring image quality and resolution.

[0061] The zoom group 20 is movable along the first direction D1. By moving along the first direction D1, the distance between the zoom group 20 and the first fixed group 10 and the second fixed group 40 is changed, thereby adjusting the focal length of the broadband zoom optical imaging system. This enables a wide range of switching between short focal lengths and long focal lengths.

[0062] When switching to short focal length mode, the zoom group 20 moves along the first direction D1 towards the first fixed group 10, reducing the distance between it and the first fixed group 10. This reduces the system's focal length and increases the field of view, thereby enabling large-area weld inspection. When switching to short focal length mode, the zoom group 20 moves along the first direction D1 towards the second fixed group 40, increasing the distance between it and the first fixed group 10 and decreasing the distance between it and the second fixed group 40. This increases the system's focal length and decreases the field of view, thereby enabling localized weld inspection.

[0063] Furthermore, the target beam passes through the zoom group 20, which, through a combination of multiple lenses, solves the problem of inconsistent focal points of different rays in the target beam after refraction, thus compensating for spherical aberration. This improves the quality and resolution of the image.

[0064] The compensation group 30 is movable along the first direction D1 to cooperate with the zoom group 20 for focal length adjustment.

[0065] When switching to short focal length mode, the compensation group 30 moves along the first direction D1 towards the zoom group 20, reducing the distance between them. This decreases the system's focal length and increases the field of view, thereby enabling large-area weld inspection. When switching back to short focal length mode, the compensation group 30 moves along the first direction D1 towards the second fixed group 40, increasing the distance between it and the zoom group 20, and decreasing the distance between it and the second fixed group 40. This increases the system's focal length and decreases the field of view, thereby enabling localized weld inspection.

[0066] Furthermore, the compensation group 30 is also used to correct broadband chromatic aberration and to transmit the target beam emitted from the convergence multiplication group 20 to the second fixed group 40.

[0067] Specifically, the compensation group 30 includes an aperture stop 31, a first negative lens 32, a first positive lens 33, and a second negative lens 34, which are arranged at intervals along the arrangement direction of the zoom group 20 and the second fixed group 40. Among them, the light-emitting surface of the first negative lens 32 and the light-incident surface of the first positive lens 33 are both diffraction surfaces, namely the first diffraction surface 321 and the second diffraction surface 331, respectively.

[0068] For example, the aperture stop 31 is a thin metal light-blocking sheet with a centrally located light-passing hole. When the target beam enters the compensation group 30 from the zoom group 20, the aperture stop 31 filters out extremely deflected light rays in the target beam to avoid aggravating aberrations. After passing through the aperture stop 31, the target beam enters the first negative lens 32. The first negative lens 32 is a spherical lens with negative optical power, its incident surface is convex, and its exit surface is concave. The sign of the optical power determines the deflection direction of the lens on the target beam. If the optical power of the lens is positive, the lens deflects the incident target beam in the direction of the target optical axis 70, thus converging the target beam; if the optical power of the lens is negative, the lens deflects the incident target beam away from the target optical axis 70, thus diverging the target beam. Therefore, the first negative lens 32 diverges the target beam, preventing excessive convergence of the target beam.

[0069] The first positive lens 33 is a spherical lens with positive optical power, and its incident surface and exit surface are both convex. The target beam enters the first positive lens 33, which converges the target beam, compensates for the divergence of the first negative lens 32, and ensures that the target beam can be imaged.

[0070] The combination of the first diffraction surface 321 of the first negative lens 32 and the second diffraction surface 331 of the first positive lens 33 functions as a double-layer diffractive optical element, exhibiting negative dispersion characteristics. Combined with the positive dispersion characteristics of the first negative lens 32 and the first positive lens 33, this allows the focal points of different wavelengths of light in the target beam within a broadband band to tend to be consistent, thereby correcting broadband chromatic aberration. Preferably, the broadband band includes the wavelength range of visible and near-infrared light, ranging from 400 nm to 1500 nm.

[0071] Furthermore, the first diffraction surface 321, through phase modulation, reduces the excessive refraction of edge field rays in the target beam, and in conjunction with the diverging effect of the first negative lens 32, initially enhances the spherical aberration correction accuracy across the entire focal length. The second diffraction surface 331 further refines the focusing deviation between the central and edge rays, and in conjunction with the first positive lens 33, further enhances the spherical aberration correction accuracy across the entire focal length. The second diffraction surface 331 can also reduce the symmetrical refraction of edge field rays in the target beam, thereby correcting off-axis aberrations such as astigmatism and coma. Coma manifests as inconsistent focal points of off-axis rays, while astigmatism manifests as the inability of off-axis rays to focus into a clear point image; off-axis rays are rays that do not coincide with the target optical axis 70.

[0072] Furthermore, the arrangement of the first diffraction plane 321 and the second diffraction plane 331 forms a dual diffraction synergy, ensuring high efficiency of broadband diffraction.

[0073] The first diffraction surface 321 and the second diffraction surface 331 mentioned above correct broadband chromatic aberration and off-axis aberration, replacing the existing structure that uses multiple lenses to correct broadband chromatic aberration and off-axis aberration, simplifying the structure and reducing the overall size and mass of the system.

[0074] The target beam passes through the first positive lens 33 and then into the second negative lens 34. The second negative lens 34 is a spherical lens with negative optical power, its incident and exit surfaces being concave. The second negative lens 34 fine-tunes the final convergence of the target beam to ensure the stability of the image plane 60 at full focal length.

[0075] The second fixed group 40 is fixedly installed in the system to lock the final imaging quality of the entire broadband zoom optical imaging system and the position of the imaging plane 60, thus avoiding disruption of the synergistic correction effect of the first fixed group 10, the zoom group 20, and the compensation group 30. When the target beam is emitted from the second negative lens 34, light rays from different fields of view cannot be focused onto the same plane, resulting in field curvature. The second fixed group 40 is mainly used to counteract the superimposed field curvature of the first fixed group 10, the zoom group 20, and the compensation group 30, and to converge the target beam onto the filter group 50.

[0076] The filter group 50 is fixedly set to ensure imaging stability. After the target beam enters the filter group 50, the filter group 50 filters the light of the required detection band, filters out stray light and harmful bands from the welding site, and avoids stray light interference that causes image blurring, so as to transmit the target beam to the imaging surface 60 and form an image. The imaging surface 60 is a flat target surface that ultimately forms a clear real image.

[0077] In summary, the broadband zoom optical imaging system of this invention improves imaging quality and resolution by using a first fixed group 10 to converge the target beam and correct system distortion, and a zoom group 20 to correct spherical aberration. The coordinated movement of the zoom group 20 and the compensation group 30 achieves a wide zoom range. The placement of the first diffraction surface 321 and the second diffraction surface 331 in the compensation group 30 reduces the overall size and mass of the system; simultaneously, it corrects broadband chromatic aberration and off-axis aberration, increasing the broadband coverage, improving diffraction efficiency, and enhancing the quality and resolution of broadband imaging. The second fixed group 40 corrects the field curvature of the target beam converged by the compensation group 30, further improving imaging quality and resolution. A filter group filters out clutter, ensuring image quality. This broadband zoom optical imaging system achieves both high-quality, high-resolution broadband imaging and a compact structure.

[0078] In some embodiments, the radius of curvature of the incident surface of the first negative lens 32 Satisfies the relationship: 12.5mm≤ ≤13.3mm. Wherein, radius of curvature... In some cases, excessive curvature and over-bending of the lens can lead to increased spherical aberration and astigmatism, resulting in decreased image resolution. In such cases, excessively flat curvature and insufficient optical power reduce the ability of the compensation group 30 to correct chromatic aberration across a wide spectral range, especially in the near-infrared band. However, within 12.5mm ≤ With a spherical aberration of ≤13.3mm, the image quality is effectively controlled and clear. Specifically, The values ​​can be 12.5mm, 12.6mm, 12.7mm, 12.8mm, 12.9mm, 13.0mm, 13.1mm, 13.2mm, and 13.3mm.

[0079] In some embodiments, the radius of curvature of the light-emitting surface of the first negative lens 32 Satisfies the relationship: 9.2mm≤ ≤9.6mm. Wherein, radius of curvature In this case, excessive curvature leads to excessive optical power of the first negative lens 32, causing misalignment with the first diffraction surface 321 and resulting in increased field curvature. Simultaneously, in In cases where the curvature is too flat, the positive lens contributes insufficiently, resulting in a decrease in system resolution in the short-wave infrared band. However, in the case of 9.2mm ≤ With a diameter ≤9.6mm, it exhibits good phase matching with the first diffraction plane 321 and excellent correction effect for broadband chromatic aberration. Specifically, The values ​​can be 9.2mm, 9.3mm, 9.4mm, 9.5mm, and 9.6mm.

[0080] In some embodiments, the radius of curvature of the incident surface of the first positive lens 33 Satisfies the relationship: 9.2mm≤ ≤9.6mm. Wherein, radius of curvature In the case of excessive curvature, the optical focal length of the first positive lens 33 becomes too strong, causing a mismatch between it and the second diffraction surface 331, resulting in an increase in field curvature. In the case of excessively flat curvature, the contribution of the first positive lens 33 is insufficient, resulting in a decrease in system resolution in the short-wave infrared band. However, in the case of 9.2mm ≤ When the diameter is ≤9.6mm, the incident surface of the first positive lens 33 and the second diffraction surface 331 have good phase matching, resulting in excellent correction of broadband chromatic aberration. Specifically, The values ​​can be 9.2mm, 9.3mm, 9.4mm, 9.5mm, and 9.6mm.

[0081] In some embodiments, the radius of curvature of the light-emitting surface of the first positive lens 33 Satisfies the relationship: -21.2mm≤ ≤-20.1mm. Wherein, the radius of curvature... In such cases, excessively negative curvature leads to increased spherical aberration. In the case of excessively flat curvature, the back surface of the first positive lens 33 contributes insufficiently, resulting in a decrease in the imaging quality of the system in the near-infrared band. However, in the case of -21.2mm≤ Within the range of ≤-20.1mm, spherical aberration and coma can be effectively controlled. Specifically, The values ​​can be -21.2mm, -21.1mm, -21.0mm, -20.9mm, -20.8mm, -20.7mm, -20.6mm, -20.5mm, -20.4mm, -20.3mm, -20.2mm, and -20.1mm.

[0082] In some embodiments, the radius of curvature of the incident surface of the second negative lens 34 is... Satisfies the relationship: -10.8mm≤ ≤-9.9mm. Wherein, radius of curvature When the curvature is less than -10.8mm, the curvature is too negative, causing the image plane to shift and increasing the distortion of the edge field of view. When the curvature is greater than -9.9mm, the curvature is too flat, resulting in insufficient optical power of the second negative lens (34), thus increasing the overall length of the system. However, when the curvature is less than or equal to -10.8mm... With a thickness of ≤-9.9mm, the image plane is flat and distortion is well controlled. Specifically, The values ​​can be -10.8mm, -10.7mm, -10.6mm, -10.5mm, -10.4mm, -10.3mm, -10.2mm, -10.1mm, -10.0mm, and -9.9mm.

[0083] In some embodiments, the radius of curvature of the light-emitting surface of the second negative lens 34 Satisfies the relationship: 87.1mm≤ ≤87.9mm. Wherein, radius of curvature In such cases, a slightly larger curvature causes the image plane to shift, resulting in a decrease in resolution at the edges of the field of view. In such cases, if the curvature is too flat, the optical power of subsequent components will be insufficient, forcing an increase in the overall length of the system. However, within 87.1mm ≤ When the image thickness is ≤87.9mm, the image plane is flat and the field curvature is well controlled. Specifically, The values ​​can be 87.1mm, 87.2mm, 87.3mm, 87.4mm, 87.5mm, 87.6mm, 87.7mm, 87.8mm, and 87.9mm.

[0084] In some embodiments, the phase distribution function of the first diffraction surface 321 of the first negative lens 32 Satisfying the relation:

[0085] ,

[0086] In the formula, The phase coefficient of the first diffraction surface 321 of the first negative lens 32; The position coordinates of the phase of the first diffraction surface 321 of the first negative lens 32. , Phase distribution function coordinate system Axis coordinates Phase distribution function coordinate system Axis coordinates; where, phase distribution function The coordinate system is a Cartesian rectangular coordinate system with the intersection of the first diffraction surface 321 of the first negative lens 32 and the target optical axis 70 as the origin. The incident direction of the target beam is the phase distribution function. coordinate system The positive direction of the axis.

[0087] By finely designing the phase of the first diffraction surface 321 through the phase distribution function, functions such as dispersion buffering, aberration correction, and beam radial distribution optimization are achieved.

[0088] In some embodiments, the phase distribution function of the first diffraction surface 321 It has five phase coefficients, namely , , , , Among them, the phase coefficient of the quadratic term Phase coefficients of quartic terms They respectively satisfy the following relations: and Dominates primary spherical aberration correction and broadband fundamental dispersion buffer; sixth-order phase coefficient 8th term phase coefficient Phase coefficient of the tenth term They respectively satisfy the following relations: , and It effectively suppresses advanced spherical aberration and improves the focusing accuracy of rays in the edge field of view.

[0089] In some embodiments, the phase distribution function of the second diffraction surface 331 of the first positive lens 33 Satisfying the relation:

[0090] ,

[0091] In the formula, Let be the phase coefficient of the incident surface of the first positive lens 33. These are the phase coordinates of the incident surface of the first positive lens 33. , Phase distribution function coordinate system Axis coordinates Phase distribution function coordinate system Axis coordinates; where, phase distribution function The coordinate system is a Cartesian rectangular coordinate system with the intersection of the incident surface of the first positive lens 33 and the optical axis 70 of the target beam as the origin. The incident direction of the target beam is the phase distribution function. coordinate system The positive direction of the axis.

[0092] By finely designing the phase of the second diffraction surface 331 through the phase distribution function, functions such as dispersion buffering, aberration correction, and beam radial distribution optimization are achieved.

[0093] In some embodiments, the phase distribution function of the first diffraction surface 321 It has five phase coefficients, namely , , , , Among them, the phase coefficient of the quadratic term Phase coefficients of quartic terms They respectively satisfy the following relations: and Dominates primary spherical aberration correction and broadband fundamental dispersion buffer; sixth-order phase coefficient 8th term phase coefficient Phase coefficient of the tenth term They respectively satisfy the following relations: , and It effectively suppresses advanced spherical aberration and improves the focusing accuracy of rays in the edge field of view.

[0094] In some embodiments, the spacing between the aperture stop 31 and the first negative lens 32 along the first direction D1 is... Satisfy the relation, Specifically, The values ​​can be 0.4mm, 0.5mm, 0.6mm, or 0.7mm.

[0095] Specifically, when the distance between the aperture stop 31 and the first negative lens 32 is less than 0.4 mm, the aperture stop 31 is close to the first negative lens 32. When the target beam is incident on the first diffraction surface 321 and the second diffraction surface 331, the proportion of edge rays is too high, leading to a sharp increase in primary spherical aberration and coma, thus reducing image quality. If the distance between the aperture stop 31 and the first negative lens 32 is greater than 0.7 mm, the aperture stop 31 is far from the first negative lens 32. The incident angle of the target beam is dispersed, and the phase difference between the light rays at the center of the first diffraction surface 321 and the center and edge of the second diffraction surface 331 increases, exacerbating broadband chromatic aberration and reducing image quality. The incident distribution and phase distribution function of the target beam on the first diffraction plane 321 are such that... and The correction rules are precisely matched to balance aberrations while ensuring high transmittance of visible and near-infrared light. This guarantees high-quality and high-resolution imaging across a wide spectral band.

[0096] In some embodiments, the Abbe number of the first negative lens 32 is set to be less than the Abbe number of the first positive lens 33. The Abbe number is a parameter characterizing the dispersion characteristics of a lens; the smaller the Abbe number, the weaker the dispersion; the larger the Abbe number, the stronger the dispersion. Chromatic aberration is the specific manifestation of dispersion. Preferably, the Abbe number of the first positive lens 33 is 1.94 to 2.04 times that of the first negative lens 32. This results in a multiple relationship between the phase delays of light rays of different wavelengths, effectively improving diffraction efficiency and further enhancing image quality and resolution.

[0097] Specifically, the first diffraction surface 321 cancels out most of the dispersion across the broad spectrum with low diffraction order and weak back dispersion, reducing chromatic aberration. It also corrects the radial distribution unevenness of the target beam through low-order phase modulation, while simultaneously improving the diffraction efficiency of visible light in the target beam. The second diffraction surface 331 cancels out the residual dispersion of the first diffraction surface 321 and the dynamic dispersion of the zoom group 20 with medium diffraction order and strong back dispersion. It also corrects off-axis aberrations through high-order phase modulation, while simultaneously improving the diffraction efficiency of near-infrared light in the target beam. This ensures high-quality and high-resolution imaging.

[0098] In some embodiments, the first fixed group 10 includes a second positive lens 11, a third negative lens 12, and a fourth negative lens 13 arranged sequentially at intervals along the arrangement direction of the first fixed group 10 and the zoom group 20.

[0099] The second positive lens 11 is a spherical lens with positive optical power, its incident surface is convex, and its radius of curvature is... Satisfying the relation: The light-emitting surface is convex, with a radius of curvature of... Satisfying the relation: The third negative lens 12 is a spherical lens with negative optical power; its incident surface is concave, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is convex, with a radius of curvature of... Satisfying the relation: The fourth negative lens 13 is a spherical lens with negative optical power, its incident surface is concave, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is concave, with a radius of curvature of... Satisfying the relation: .

[0100] In some embodiments, The possible values ​​are 46.8mm, 46.9mm, 47.0mm, 47.1mm, 47.2mm, and 47.3mm. The values ​​can be 81.2mm, 81.3mm, 81.4mm, 81.5mm, 81.6mm, 81.7mm, 81.8mm, 81.9mm, 82.0mm, 82.1mm, 82.2mm, and 82.3mm. The values ​​can be -62.9mm, -62.8mm, -62.7mm, -62.6mm, -62.5mm, -62.4mm, -62.3mm, -62.2mm, -62.1mm, and -62.0mm. The values ​​can be -76.1mm, -76.0mm, -75.9mm, -75.8mm, -75.7mm, -75.6mm, -75.5mm, -75.4mm, -75.3mm, and -75.2mm. The values ​​can be -109.1mm, -109.0mm, -108.9mm, -108.8mm, -108.7mm, -108.6mm, -108.5mm, -108.4mm, -108.3mm, and -108.2mm. The values ​​can be 404.1mm, 404.2mm, 404.3mm, 404.4mm, 404.5mm, 404.6mm, 404.8mm, and 404.9mm.

[0101] Specifically, after the target beam enters the second positive lens 11, the second positive lens 11 deflects the light rays at the edge of the target beam's field of view toward a direction closer to the target optical axis 70, thereby converging the target beam and performing preliminary compensation for spherical aberration.

[0102] Furthermore, the target beam is transmitted from the second positive lens 11 to the third negative lens 12. The light rays in the central field of view of the target beam are deflected in a direction away from the target optical axis 70, while the light rays in the edge field of view are deflected more gently, which cancels out part of the converging effect of the second positive lens 11, making the deflection of the light rays in each field of view of the target beam more symmetrical, thereby balancing the total optical power of the first fixed group 10 and correcting the coma remaining in the second positive lens 11.

[0103] Furthermore, when the target beam passes through the third negative lens 12 into the fourth negative lens 13, the light rays in the central field of view of the target beam continue to deflect away from the target optical axis 70, while the light rays in the edge field of view deflect more gently. This ensures that the divergence of the target beam precisely matches the requirements of the subsequent zoom group 20 and corrects the astigmatism remaining in the third negative lens 12, guaranteeing the quality of the image. By diverging the target beam, the radial dimension of the target beam is controlled, avoiding excessive size of subsequent components and ensuring the compactness of the system structure.

[0104] In some embodiments, the zoom group 20 includes a fifth negative lens 21, a sixth negative lens 22, a seventh negative lens 23, and a third positive lens 24, which are arranged at intervals along the arrangement direction of the first fixed group 10 and the compensation group 30.

[0105] The fifth negative lens 21 is a spherical lens with negative optical power, its incident surface is convex, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is concave, with a radius of curvature of... Satisfying the relation: The sixth negative lens 22 is a spherical lens with negative optical power. Its incident surface is convex, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is concave, with a radius of curvature of... Satisfying the relation: The seventh negative lens 23 is a spherical lens with negative optical power. Its incident surface is concave, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is concave, with a radius of curvature of... Satisfying the relation: The third positive lens 24 is a spherical lens with positive optical power, its incident surface is convex, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is convex, with a radius of curvature of... Satisfying the relation: .

[0106] In some embodiments, The values ​​can be 22.8mm, 22.9mm, 23.0mm, 23.1mm, 23.2mm, 23.3mm, 23.4mm, 23.5mm, 23.6mm, 23.7mm, 23.8mm, and 23.9mm. The values ​​can be 19.8mm, 19.9mm, 20.0mm, 20.1mm, 20.2mm, 20.3mm, 20.4mm, and 20.5mm; The values ​​can be 88.1mm, 88.2mm, 88.3mm, 88.4mm, 88.5mm, 88.6mm, 88.7mm, 88.8mm, and 88.9mm. The values ​​can be 25.1mm, 25.2mm, 25.3mm, 25.4mm, 25.5mm, 25.6mm, 25.7mm, 25.8mm, and 25.9mm. The values ​​can be -34.1mm, -34.0mm, -33.9mm, -33.8mm, -33.7mm, -33.6mm, -33.5mm, -33.4mm, -33.3mm, -33.2mm, and -33.1mm. The values ​​can be 26.9mm, 27.0mm, 27.1mm, 27.2mm, 27.3mm, 27.4mm, and 27.5mm. The possible values ​​are 34.8mm, 34.9mm, 35.0mm, 35.1mm, 35.2mm, 35.3mm, 35.4mm, 35.5mm, and 35.6mm. The values ​​can be -138.1mm, -138.0mm, -137.9mm, -137.8mm, -137.6mm, -137.5mm, -137.4mm, -137.3mm, -137.2mm, and -137.1mm.

[0107] Specifically, the target beam is initially diverged by the fifth negative lens 21, providing the sixth negative lens 22 with a target beam in a controllable divergence state and correcting the primary spherical aberration of the first fixed group 10 in the preceding stage.

[0108] Furthermore, the target beam is transmitted to the sixth negative lens 22, which further diverges the target beam to balance the coma during the zoom process, making the off-axis rays more symmetrical and improving the imaging quality.

[0109] Furthermore, the target beam is transmitted from the sixth negative lens 22 to the seventh negative lens 23, which further diverges the target beam and further corrects the residual coma and astigmatism during the zoom process.

[0110] Furthermore, the target beam diverged by the seventh negative lens 23 is transmitted to the third positive lens 24. The third positive lens 24 converges the diverged target beam and transmits it to the compensation group 30, and corrects the residual spherical aberration of the zoom group 20, thus ensuring the sharpness of the full focal length imaging.

[0111] In some embodiments, the second fixing group 40 includes an eighth negative lens 41 and a fourth positive lens 42 arranged sequentially and at intervals along the arrangement direction of the compensation group 30 and the filter group 50. The eighth negative lens 41 is a spherical lens with negative optical power, its incident surface is concave, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is also concave, with a radius of curvature of... Satisfying the relation: The fourth positive lens 42 is a spherical lens with positive optical power, its incident surface is convex, and its radius of curvature is... Satisfying the relation: Its light-emitting surface is also convex, with a radius of curvature of... Satisfying the relation: .

[0112] In some embodiments, The values ​​can be -48.7mm, -48.6mm, -48.5mm, -48.4mm, -48.3mm, -48.2mm, -48.1mm, -48.0mm, -47.9mm, -47.8mm, -47.7mm, -47.6mm, -47.5mm, -47.4mm, -47.3mm, -47.2mm, and -47.1mm. The values ​​can be 41.7mm, 41.8mm, 41.9mm, 42.0mm, 42.1mm, 42.2mm, 42.3mm, 42.4mm, 42.5mm, 42.6mm, and 42.7mm. The values ​​can be 34.8mm, 34.9mm, 35.0mm, 35.1mm, 35.2mm, 35.3mm, 35.4mm, 35.5mm, 35.6mm, and 35.7mm. The values ​​can be -15.1mm, -15.0mm, -14.9mm, -14.8mm, -14.7mm, -14.6mm, and -14.5mm.

[0113] Specifically, the modulated target beam is transmitted to the eighth negative lens 41. The light rays in the edge field of view of the target beam are deflected to the outside of the target optical axis 70, while the light rays in the center field of view are deflected less, so that the focal points of the light rays in the center field of view and the edge field of view tend to be on the same plane, thereby reducing field curvature and helping to eliminate spherical aberration.

[0114] Furthermore, the target beam deflected by the eighth negative lens 41 is transmitted to the fourth positive lens 42. The fourth positive lens 42 refocuses the target beam towards the inside of the target optical axis 70, thereby adjusting the sharpness and brightness of the central and peripheral fields of view, and further adjusting the broadband chromatic aberration to ensure the uniformity of the image. Furthermore, the fourth positive lens 42, in conjunction with the eighth negative lens 41, balances the final optical power of the system, ensuring stable imaging position at full focal length and preventing image shift during zooming.

[0115] In some embodiments, the filter group 50 mainly includes a long-wavelength cutoff filter 51 and a short-wavelength cutoff filter 52. The long-wavelength cutoff filter 51 has a cutoff band of... Satisfying the relation: Near-infrared light has wavelengths between 800 nm and 1400 nm, while near-infrared light has wavelengths between 1400 nm and 1500 nm, which are considered short-wave near-infrared light. Therefore, the long-wave cutoff filter 51 can filter out short-wave near-infrared light with wavelengths greater than 800 nm and less than 1500 nm, as well as some long-wave near-infrared light. Wavelengths below 800 nm but above 760 nm remain short-wave near-infrared light, while wavelengths below 760 nm but above 380 nm are visible light. Therefore, the long-wave cutoff filter 51 allows some short-wave near-infrared light with wavelengths less than 800 nm and visible light to pass through.

[0116] The cutoff band of the short-wave cutoff filter 52 Then the following relation is satisfied: This filters out some short-wave near-infrared and visible light with wavelengths between 400nm and 800nm, while allowing short-wave near-infrared and long-wave near-infrared light with wavelengths greater than 800nm ​​to pass through.

[0117] The long-wavelength cutoff filter 51 and the short-wavelength cutoff filter 52 can eliminate stray light interference and ensure broadband imaging stability according to system requirements.

[0118] Depending on the system's different filtering requirements, either the long-wavelength cutoff filter 51 or the short-wavelength cutoff filter 52 is switched into the optical path. Specifically, the long-wavelength cutoff filter 51 and the short-wavelength cutoff filter 52 are respectively disposed around the circumference of the filter wheel, which is rotatable around the first direction D1. By rotating the filter wheel, either the long-wavelength cutoff filter 51 or the short-wavelength cutoff filter 52 is switched into the optical path, at which point the long-wavelength cutoff filter 51 or the short-wavelength cutoff filter 52 coincides with the target optical axis 70 along the central axis of the first direction D1. This ensures that the system meets the filtering requirements of different wavelengths across a wide spectral range, thereby improving the imaging quality.

[0119] Working principle:

[0120] As a preferred embodiment, refer to Figures 1 to 3 The figures shown are schematic diagrams of the short focal length, medium focal length, and long focal length states of a broadband zoom optical imaging system.

[0121] The total length L of the broadband zoom optical imaging system satisfies 148mm≤L≤152mm, with the preferred total length L being 150mm, ensuring a compact structure while retaining space design redundancy.

[0122] In some embodiments, the total length L of the broadband zoom optical imaging system can also be 148mm, 149mm, 151mm, or 152mm.

[0123] Therefore, the distances between the components under different focal lengths are shown in Table 1.

[0124] Table 1 Distances between components

[0125]

[0126] The parameters of the lenses in each component are shown in Table 2.

[0127] Table 2 Geometric parameters of each lens

[0128]

[0129] The Abbe number of the first negative lens 32 is preferably 32.2, the Abbe number of the first positive lens 33 is preferably 64.2, and the Abbe number of the second negative lens 34 is preferably 60.3.

[0130] If the Abbe number of the first negative lens 32 is too small, the material dispersion will be too large, resulting in poor chromatic aberration correction with the first diffraction surface 321, especially degrading the imaging quality in the visible light band. Conversely, if the Abbe number of the first negative lens 32 is too large, the material's dispersion capability will be insufficient, leading to an excessive correction burden on the first diffraction surface 321 and insufficient chromatic aberration correction in the near-infrared band. Therefore, when the Abbe number of the first negative lens 32 is preferably 32.2, the material and the diffraction surface form a complementary dispersion relationship, resulting in the best chromatic aberration correction effect across the broad spectrum.

[0131] If the Abbe number of the first positive lens 33 is too small, its dispersive ability will be insufficient, resulting in inadequate chromatic aberration correction when combined with the first negative lens 32. Conversely, if the Abbe number of the first positive lens 33 is too large, its dispersive ability will be too strong, leading to over-correction of chromatic aberration, especially in the long-wavelength direction, resulting in inverse chromatic aberration. However, when the Abbe number of the first positive lens 33 is preferably 64.2, a good dispersion balance is formed between the first positive lens 33, the first negative lens 32, the first diffraction surface 321, and the second diffraction surface 331, effectively correcting chromatic aberration across a wide spectral range.

[0132] The Abbe number of the second negative lens 34 should not be too small, otherwise the material dispersion will be too large, making broadband chromatic aberration correction difficult, especially in the transition band between visible and near-infrared light. At the same time, it should not be too large either, otherwise the material dispersion capability will be insufficient, leading to a mismatch in dispersion with the first positive lens 33 and insufficient chromatic aberration correction in the near-infrared band. Therefore, the preferred Abbe number of the second negative lens 34 is 60.3, which can form a good dispersion complementarity with the first positive lens 33 and work in conjunction with the second diffraction surface 331 to achieve broadband chromatic aberration balance correction.

[0133] At this point, calculations show that the zoom range of the broadband zoom optical imaging system is 20mm to 120mm, and the operating wavelength is 400nm to 1500nm. Using the visible light band of 400nm to 760nm, visible defects such as weld surface morphology, color changes, and oxide layers can be clearly detected. Utilizing the near-infrared band of 760nm to 1500nm, with its strong anti-interference capability and penetrating power, it can monitor the temperature distribution of the molten pool and changes in the heat-affected zone, as well as defects such as porosity and lack of fusion within the weld.

[0134] At the same time, like Fang The number ranges from 3.4 to 4.8; system fluctuation. The range of the number is 3.3 to 3.9.

[0135] In telephoto mode, total focal length The range is Preferably 120mm; object-side field of view The range of values ​​is The preferred angle is 4.7°. In short focal length mode, the total focal length... The range is Preferably 20mm; object-side field of view The range of values ​​is The optimal zoom angle is 28.1°. This achieves a 6x zoom ratio, ensuring both compatibility and image quality while maintaining a wide zoom range.

[0136] In some embodiments, in the telephoto mode, the total focal length It can also be 116mm, 118mm, 122mm, and 124mm, object-side field of view. It can also be 4.1°, 4.2°, 4.3°, 4.4°, 4.5°, 4.6°, 4.8°, 4.9°, 5.0°, 5.1°, 5.2°; total focal length in short focal length mode. It can also be 18mm or 22mm, object-side field of view. It can also be 27.7°, 27.8°, 27.9°, 28.0°, 28.2°, 28.3°, or 28.4°.

[0137] The phase coefficients of the first diffraction surface 321 and the second diffraction surface 331 are further set to determine the phase distribution functions of the first diffraction surface 321 and the second diffraction surface 331. Preferably, the quadratic phase coefficient of the first diffraction surface 321... quartic phase coefficient Phase coefficient of the sixth term octet phase coefficient Phase coefficient of the tenth term Phase coefficient of the quadratic term of the second diffraction plane 331 quartic phase coefficient Phase coefficient of the sixth term octet phase coefficient Phase coefficient of the tenth term .

[0138] Based on the above design parameters, the optical performance of the broadband zoom optical imaging system under different focal lengths is analyzed.

[0139] Reference Figure 4 The figure shows ray tracing point diagrams in the visible light band with wavelengths from 400nm to 760nm under short, medium, and long focal length conditions, used to analyze image quality. The focal length in the medium focal length condition is 90mm. As can be seen from the figure, regardless of whether it is in the short, medium, or long focal length condition, the root mean square radius of each field of view point diagram is less than 10.664μm, indicating good image quality.

[0140] Reference Figures 5 to 7 The figure shows the MTF (Mean Transfer Function) curves of the corresponding image planes in the visible light band (400nm to 760nm) at short, medium, and long focal lengths, used to analyze image quality. As can be seen from the figure, regardless of the focal length (short, medium, or long), within a zoom range of 40 lp / mm, the optical transfer function (MTF) across the entire working wavelength and field of view is greater than 0.65, approaching the diffraction limit. The curves are smooth and compact, indicating that this system produces clear and uniform images with excellent image quality in the visible light band and across the entire field of view.

[0141] The distortion of an image represents the degree of image deformation; therefore, the degree of distortion determines its quality and resolution. (Refer to...) Figures 8 to 10 As shown in the figure, the vertical axis represents the normalized field of view, and the horizontal axis represents the percentage of image distortion under each field of view. The figure shows that in the visible light band with wavelengths from 400nm to 760nm, regardless of whether it is a short focal length, medium focal length, or long focal length, the maximum distortion within the normalized field of view does not exceed 4.1%, indicating low image distortion and high image quality and resolution.

[0142] Reference Figure 11 The figure shows the ray tracing point diagrams in the near-infrared band with wavelengths from 760nm to 1500nm under short-focus, medium-focus, and long-focus conditions. As can be seen from the figure, regardless of the focal length (short-focus, medium-focus, or long-focus) condition, the root mean square radius of the point diagrams in each field of view is less than 13.462μm, indicating good imaging quality.

[0143] Reference Figures 12 to 14The figure shows the optical transfer function (MTF) on the corresponding image planes of various fields of view in the near-infrared band (760nm to 1500nm) under short, medium, and long focal length conditions. As can be seen from the figure, regardless of the focal length (short, medium, or long), within a zoom range of 40 lp / mm, the optical transfer function across the entire working wavelength and field of view is greater than 0.4, approaching the diffraction limit. The curves are smooth and compact, indicating that this system produces clear and uniform imaging with excellent image quality in the visible light band and across the entire field of view.

[0144] The distortion in the near-infrared band (760 nm to 1500 nm) was analyzed under short-focus, medium-focus, and long-focus conditions. (Refer to...) Figures 15 to 17 As shown in the figure, the vertical axis represents the normalized field of view, and the horizontal axis represents the percentage of image distortion under each field of view. The figure shows that, regardless of whether the image is in short-focus, medium-focus, or long-focus mode, the maximum distortion within the normalized field of view does not exceed 4.2%, resulting in a small degree of image distortion and high image quality and resolution.

[0145] The energy concentration of the focused image was analyzed under short, medium, and long focal length conditions. Figures 18 to 20 It can be seen that, regardless of whether it is in short focal length, medium focal length or long focal length, more than 90% of the energy is concentrated in the Airy spot area. The energy is relatively concentrated, which ensures the high quality and high resolution of the image.

[0146] Diffraction efficiency is a core indicator of the efficiency of light energy utilization in a target beam, and it determines the quality of the image. (Refer to...) Figure 21 As shown, the diffraction efficiency is 86% at its minimum over a wide wavelength range, maintaining high diffraction efficiency throughout. This has minimal impact on the actual imaging quality, ensuring high-quality and high-resolution imaging.

[0147] In a high-zoom optical system, the cam profile is the key component controlling the precise movement of the lenses in the zoom group 20 and compensation group 30 along the target optical axis 70. (Refer to...) Figure 22 As shown in the figure, the horizontal axis represents the moving distance of the zoom group 20 and the compensation group 30 along the target optical axis 70, and the vertical axis represents the system focal length. As can be seen from the figure, the cam curve of the broadband zoom optical system has a smooth transition without any inflection points, facilitating cam mechanical design, ease of manufacturing, and high system stability.

[0148] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0149] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0150] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A wide spectral band zoom optical imaging system for weld seam detection, characterized by, include: A first fixed group, a variable magnification group, a compensation group, a second fixed group, and a filter group are arranged sequentially along the first direction; The first fixed group is fixedly set and is used to correct distortion and converge the target beam to the zoom group; The zoom group is movably disposed along the first direction, and the zoom group is used to correct spherical aberration; The compensation group is movably arranged along the first direction. The compensation group is used to correct broadband chromatic aberration and converge the target beam to the second fixed group. The compensation group includes an aperture stop, a first negative lens, a first positive lens and a second negative lens arranged sequentially and at intervals along the arrangement direction of the zoom group and the second fixed group. The light-emitting surface of the first negative lens and the light-incident surface of the first positive lens are both set as diffraction surfaces. The second fixing group is fixedly installed and is used to correct the field curvature and converge the target beam to the filter group; The filter array is fixedly installed and is used to filter the target beam to achieve imaging.

2. The broadband zoom optical imaging system for weld inspection according to claim 1, characterized in that: The radius of curvature of the incident surface of the first negative lens Satisfies the relation 12.5mm≤ ≤13.3mm; the radius of curvature of the light-emitting surface of the first negative lens Satisfies the relation, 9.2mm≤ ≤9.6mm; The radius of curvature of the incident surface of the first positive lens Satisfies the relation, 9.2mm≤ ≤9.6mm; Radius of curvature of the light-emitting surface of the first positive lens The relation is satisfied: -21.2mm ≤ ≤-20.1mm; The radius of curvature of the incident surface of the second negative lens The relationship is satisfied: -10.8mm ≤ ≤-9.9mm; Radius of curvature of the light-emitting surface of the second negative lens Satisfies the relation, 87.1mm≤ ≤87.9mm.

3. The broadband zoom optical imaging system for weld inspection according to claim 1, characterized in that: Phase distribution function of the light-emitting surface of the first negative lens Satisfying the relation: ， In the formula, The phase coefficient of the light-emitting surface of the first negative lens; Let be the phase coordinates of the light-emitting surface of the first negative lens. , The phase distribution function coordinate system Axis coordinates The phase distribution function coordinate system Axis coordinates; wherein, the phase distribution function The coordinate system is a Cartesian rectangular coordinate system with the intersection of the light-emitting surface of the first negative lens and the optical axis of the target as the origin. The incident direction of the target beam is the phase distribution function. coordinate system The positive direction of the axis; The phase coefficient of the light-emitting surface of the first negative lens satisfies the following relationship. , , , , .

4. The broadband zoom optical imaging system for weld inspection according to claim 1, characterized in that: The phase distribution function of the light entrance surface of the first positive lens satisfies the relationship: ， In the formula, Let be the phase coefficient of the incident surface of the first positive lens. Let be the phase coordinates of the incident surface of the first positive lens. , The phase distribution function coordinate system Axis coordinates The phase distribution function coordinate system Axis coordinates; wherein, the phase distribution function The coordinate system is a Cartesian rectangular coordinate system with the intersection of the incident surface of the first positive lens and the optical axis of the target beam as the origin. The incident direction of the target beam is the phase distribution function. coordinate system The positive direction of the axis; The phase coefficient of the incident surface of the first positive lens satisfies the following relationship. , , , , .

5. The broadband zoom optical imaging system for weld inspection according to claim 1, characterized in that: a separation distance between the aperture stop and the first negative lens along the first direction satisfies a relationship, .

6. The broadband zoom optical imaging system for weld inspection according to claim 1, characterized in that: The Abbe number of the first negative lens is set to be less than the Abbe number of the first positive lens.

7. The broadband zoom optical imaging system for weld inspection according to any one of claims 1 to 6, characterized in that: The first fixed group includes a second positive lens, a third negative lens, and a fourth negative lens arranged at intervals along the arrangement direction of the first fixed group and the zoom group; The radius of curvature of the incident surface of the second positive lens Satisfy the relation, The radius of curvature of the light-emitting surface of the second positive lens Satisfy the relation, ; The radius of curvature of the incident surface of the third negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the third negative lens Satisfy the relation, ; The curvature radius of the light entrance surface of the fourth negative lens satisfies a relationship, The curvature radius of the light exit surface of the fourth negative lens satisfies a relationship, .

8. The broadband zoom optical imaging system for weld inspection according to any one of claims 1 to 6, characterized in that: The zoom group includes a fifth negative lens, a sixth negative lens, a seventh negative lens, and a third positive lens, which are arranged at intervals along the arrangement direction of the first fixed group and the compensation group. a radius of curvature of an entrance surface of the fifth negative lens satisfies a relationship, a radius of curvature of an exit surface of the fifth negative lens satisfies a relationship, ; The radius of curvature of the incident surface of the sixth negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the sixth negative lens Satisfy the relation, ; The radius of curvature of the incident surface of the seventh negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the seventh negative lens Satisfy the relation, ; The radius of curvature of the incident surface of the third positive lens Satisfy the relation, The radius of curvature of the light-emitting surface of the third positive lens Satisfy the relation, .

9. The broadband zoom optical imaging system for weld inspection according to any one of claims 1 to 6, characterized in that: The second fixing group includes an eighth negative lens and a fourth positive lens arranged at intervals along the arrangement direction of the compensation group and the filter group; The radius of curvature of the incident surface of the eighth negative lens Satisfy the relation, The radius of curvature of the light-emitting surface of the eighth negative lens Satisfy the relation, ; a radius of curvature of an entrance surface of the fourth positive lens satisfies a relationship, ; a radius of curvature of an exit surface of the fourth positive lens satisfies a relationship, .

10. The broadband zoom optical imaging system for weld inspection according to any one of claims 1 to 6, characterized in that: The filter group includes a long-wavelength cutoff filter and a short-wavelength cutoff filter; the cutoff band of the long-wavelength cutoff filter... Satisfy the relation, The cutoff band of the short-wave cutoff filter Satisfy the relation, .

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