A long focal length industrial lens

Abstract

The utility model discloses an embodiment of long focus industry lens, including the first lens of positive refractive power, the second lens of positive refractive power, the third lens of negative refractive power, the fourth lens of negative refractive power, the fifth lens of positive refractive power, the sixth lens of positive refractive power and the seventh lens of negative refractive power that arrange in order from object side to image side along optical axis, the first lens to the seventh lens satisfy specific proportion range. The utility model embodiment can realize that distortion is less than 0.1% under the condition of meeting the field of view angle demand, and the size of aperture is 2.0, that is, realizes big aperture, meets still having enough light quantity under the environment of relatively dark, increases the detection scanning precision of industry lens, meets still having enough precision under scanning at 2.4 meters distance.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, and in particular to a telephoto industrial lens. Background Technology

[0002] With the increasing demand for industrial lenses, the market requirements for telephoto industrial lenses are growing rapidly. The requirements for lens parameters such as high resolution and low distortion are becoming more and more stringent. At the same time, due to the small field of view, the overall light intake of the optical system is limited, resulting in a significant decrease in accuracy in dark working environments. Utility Model Content

[0003] This utility model provides a telephoto industrial lens that achieves distortion of less than 0.1% and an aperture of f / 2.0 while meeting the field of view requirements, ensuring sufficient light intake even in relatively dark environments and increasing the detection and scanning accuracy of the industrial lens.

[0004] This utility model embodiment provides a telephoto industrial lens, including a first lens with positive optical power, a second lens with positive optical power, a third lens with negative optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, and a seventh lens with negative optical power, arranged sequentially along the optical axis from the object side to the image side.

[0005] The first lens through the seventh lens satisfy the following conditions:

[0006] 0.638 < φ1 / φ < 0.98;

[0007] 0.370 < φ2 / φ < 1.139;

[0008] -2.137 < φ3 / φ < -1.595;

[0009] -1.609 < φ4 / φ < -0.762;

[0010] 0.503 < φ5 / φ < 1.817;

[0011] 1.064 < φ6 / φ < 1.536;

[0012] -0.900 < φ7 / φ < -0.026;

[0013] Wherein, φ1, φ2, φ3, φ4, φ5, φ6, and φ7 are the optical powers of the first lens to the seventh lens, respectively, and φ is the total optical power of the telephoto industrial lens.

[0014] Optionally, the object-side surface of the first lens is convex, and the image-side surface is either convex or concave.

[0015] The object-side surface of the second lens is convex, and the image-side surface is either convex or concave.

[0016] The object-side surface of the third lens is concave, and the image-side surface is also concave.

[0017] The fourth lens has a concave side surface and a concave side surface;

[0018] The object side of the fifth lens is convex or concave, and the image side is convex.

[0019] The object-side surface of the sixth lens is convex, and the image-side surface is also convex.

[0020] The object side of the seventh lens is concave, and the image side is either convex or concave.

[0021] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all glass spherical lenses.

[0022] Optionally, the surfaces of the second lens and the third lens adjacent to each other are cemented together to form a cemented lens group.

[0023] Optionally, the second lens and the third lens satisfy the following conditions:

[0024] 1.55≤Nd2≤1.61; 55≤Vd2≤85;

[0025] 1.56≤Nd3≤1.71; 25≤Vd3≤35.9;

[0026] Wherein, Nd2 and Nd3 are the refractive indices of the second lens and the third lens, respectively, and Vd2 and Vd3 are the Abbe numbers of the second lens and the third lens, respectively.

[0027] Optionally, the surfaces of the fourth lens and the fifth lens adjacent to each other are cemented together to form a cemented lens group.

[0028] Optionally, the fourth lens and the fifth lens satisfy the following conditions:

[0029] 1.46≤Nd⁴≤1.65; 20≤Vd⁴≤35.7;

[0030] 1.79≤Nd5≤1.95; 31.9≤Vd5≤80;

[0031] Wherein, Nd4 and Nd5 are the refractive indices of the fourth lens and the fifth lens, respectively, and Vd4 and Vd5 are the Abbe numbers of the fourth lens and the fifth lens, respectively.

[0032] Optionally, it may also include an aperture stop located between the third lens and the fourth lens.

[0033] Optionally, the telephoto industrial lens satisfies the following condition: 2.765 ≤ EFL / BFL ≤ 3.267;

[0034] Wherein, EFL is the focal length of the telephoto industrial lens, and BFL is the back focal length of the telephoto industrial lens.

[0035] Optionally, the telephoto industrial lens satisfies the following condition: |Dis|≤0.1%;

[0036] Where Dis represents the distortion of the telephoto industrial lens.

[0037] The technical solution of this utility model embodiment, through the precise combination of the optical power of seven lenses, can achieve a telephoto lens. At the same time, while meeting the field of view requirements, it can also achieve distortion of less than 0.1% and an aperture size of 2.0, which is a large aperture. This ensures sufficient light intake even in relatively dark environments, increases the detection and scanning accuracy of the industrial lens, and ensures sufficient accuracy when scanning at a distance of 2.4 meters. Ultimately, it realizes a telephoto industrial lens with high resolution, low distortion, and sufficient light intake. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 1 of this utility model;

[0039] Figure 2 for Figure 1 The diagram shows the axial aberration of a telephoto industrial lens.

[0040] Figure 3 for Figure 1 The diagram shows the chromatic aberration of a telephoto industrial lens.

[0041] Figure 4 for Figure 1 The field curvature distortion diagram of the telephoto industrial lens is shown.

[0042] Figure 5 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 2 of this utility model;

[0043] Figure 6 for Figure 5 The diagram shows the axial aberration of a telephoto industrial lens.

[0044] Figure 7 for Figure 5 The diagram shows the chromatic aberration of a telephoto industrial lens.

[0045] Figure 8 for Figure 5The field curvature distortion diagram of the telephoto industrial lens is shown.

[0046] Figure 9 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 3 of this utility model;

[0047] Figure 10 for Figure 9 The diagram shows the axial aberration of a telephoto industrial lens.

[0048] Figure 11 for Figure 9 The diagram shows the chromatic aberration of a telephoto industrial lens.

[0049] Figure 12 for Figure 9 The image shows the field curvature distortion of a telephoto industrial lens. Detailed Implementation

[0050] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0051] The terminology used in the embodiments of this utility model is for the purpose of describing specific embodiments only and is not intended to limit the utility model. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this utility model are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this utility model. Furthermore, in the context, it should be understood that when referring to an element being formed "upper" or "lower" of another element, it can be formed not only directly "upper" or "lower" of the other element, but also indirectly "upper" or "lower" of the other element through an intermediate element. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0052] The term "comprising" and its variations as used in this utility model are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0053] It should be noted that the concepts of "first" and "second" mentioned in this utility model are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0054] It should be noted that the terms "a" and "a plurality of" used in this utility model are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0055] Figure 1 This is a structural schematic diagram of a telephoto industrial lens provided in Embodiment 1 of this utility model, for reference. Figure 1 The telephoto industrial lens includes a first lens 1 with positive optical power, a second lens 2 with positive optical power, a third lens 3 with negative optical power, a fourth lens 4 with negative optical power, a fifth lens 5 with positive optical power, a sixth lens 6 with positive optical power, and a seventh lens 7 with negative optical power, arranged sequentially from the object side to the image side along the optical axis.

[0056] Lenses 1 through 7 satisfy the following conditions: 0.638 < φ1 / φ < 0.98; 0.370 < φ2 / φ < 1.139; -2.137 < φ3 / φ < -1.595; -1.609 < φ4 / φ < -0.762; 0.503 < φ5 / φ < 1.817; 1.064 < φ6 / φ < 1.536; -0.900 < φ7 / φ < -0.026; where φ1, φ2, φ3, φ4, φ5, φ6, and φ7 are the optical powers of lenses 1 through 7 respectively, and φ is the total optical power of the telephoto industrial lens.

[0057] First, for optical lenses, optical power equals the difference between the image-side beam convergence and the object-side beam convergence; it characterizes the optical system's ability to deflect light. The larger the absolute value of optical power, the stronger the bending ability of light; the smaller the absolute value, the weaker the bending ability. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).

[0058] In the telephoto industrial lens provided in this embodiment, all lenses can be housed in a single lens barrel. Figure 1 (not shown in the image) such as Figure 1As shown, in one specific embodiment, the telephoto industrial lens may further include an aperture stop STO, located between the third lens 3 and the fourth lens 4. In this embodiment, the first lens 1 and the second lens 2 are configured as lenses with positive optical power, allowing light entering the optical system to smoothly transition to the aperture stop STO. Simultaneously, the third lens 3 is configured as a lens with negative optical power, meeting the large aperture requirement of the optical system. The fourth lens 4, fifth lens 5, sixth lens 6, and seventh lens 7 are arranged in a negative-positive-positive-negative configuration. This configuration effectively corrects aberrations in the entire optical system behind the aperture stop STO, enabling the lens to meet high resolution requirements. This configuration also reduces lens distortion, achieving a low-distortion effect. Furthermore, in this embodiment of the present invention, by setting the optical power of the seven lenses and the total optical power of the entire lens to meet the above-mentioned specific ratio range, the essence is to limit the size of the optical power of different lenses in the optical system so that the optical power of the optical system can be reasonably distributed, which can reduce the tolerance sensitivity of the optical system, effectively improve the imaging quality of the optical system, and also improve the production yield to a certain extent.

[0059] The industrial lens provided in this embodiment of the utility model can achieve telephoto capability through the precise combination of the optical power of seven lenses. At the same time, while meeting the field of view requirements, it can also achieve distortion of less than 0.1% and an aperture size of 2.0, which is a large aperture. This ensures sufficient light intake even in relatively dark environments, increases the detection and scanning accuracy of the industrial lens, and ensures sufficient accuracy when scanning at a distance of 2.4 meters. Ultimately, it realizes a telephoto industrial lens with high resolution, low distortion, and sufficient light intake.

[0060] In one specific embodiment, optionally, the object-side surface of the first lens 1 is convex, and the image-side surface is either convex or concave; the object-side surface of the second lens 2 is convex, and the image-side surface is either convex or concave; the object-side surface of the third lens 3 is concave, and the image-side surface is concave; the object-side surface of the fourth lens 4 is concave, and the image-side surface is concave; the object-side surface of the fifth lens 5 is either convex or concave, and the image-side surface is convex; the object-side surface of the sixth lens 6 is convex, and the image-side surface is convex; and the object-side surface of the seventh lens 7 is concave, and the image-side surface is either convex or concave.

[0061] In one specific embodiment, optionally, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 are all glass spherical lenses.

[0062] In one specific embodiment, the adjacent surfaces of the second lens 2 and the third lens 3 may be cemented together to form a cemented lens group.

[0063] Furthermore, the second lens 2 and the third lens 3 satisfy the following conditions: 1.55≤Nd2≤1.61; 55≤Vd2≤85; 1.56≤Nd3≤1.71; 25≤Vd3≤35.9; where Nd2 and Nd3 are the refractive indices of the second lens 2 and the third lens 3, respectively, and Vd2 and Vd3 are the Abbe numbers of the second lens 2 and the third lens 3, respectively.

[0064] In one specific embodiment, optionally, the adjacent surfaces of the fourth lens 4 and the fifth lens 5 are cemented together to form a cemented lens group.

[0065] Furthermore, the fourth lens 4 and the fifth lens 5 satisfy the following conditions: 1.46≤Nd4≤1.65; 20≤Vd4≤35.7; 1.79≤Nd5≤1.95; 31.9≤Vd5≤80; where Nd4 and Nd5 are the refractive indices of the fourth lens 4 and the fifth lens 5, respectively, and Vd4 and Vd5 are the Abbe numbers of the fourth lens 4 and the fifth lens 5, respectively.

[0066] In the above embodiments, the use of all-glass lenses improves lens stability and ensures sufficient resolution under different usage conditions. Furthermore, the cemented lens group effectively corrects chromatic aberration in the optical system. Using the aforementioned cemented lens group effectively enhances the optical system's ability to correct chromatic aberration, further meeting the chromatic aberration requirements of industrial lenses.

[0067] Furthermore, as those skilled in the art will know, the refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium, primarily used to describe a material's ability to refract light; different materials have different refractive indices. The Abbe constant, on the other hand, is an index used to represent the dispersion ability of a transparent medium; the more severe the dispersion of the medium, the smaller the Abbe constant; conversely, the less severe the dispersion, the larger the Abbe constant. Therefore, in the above embodiments, by further limiting the refractive indices and Abbe numbers of the second lens 2 and the third lens 3, as well as the fourth lens 4 and the fifth lens 5 that make up the cemented lens group, the effect of the cemented lens on chromatic aberration correction of the optical system can be better improved, thereby enhancing the overall imaging quality of the lens.

[0068] In one specific embodiment, optionally, the telephoto industrial lens satisfies the following condition: 2.765≤EFL / BFL≤3.267; where EFL is the focal length of the telephoto industrial lens and BFL is the back focal length of the telephoto industrial lens.

[0069] In this embodiment, by limiting the range of the ratio of the lens's focal length to its back focal length to meet the above requirements, the lens can meet the focal length requirements while ensuring that the imaging sensor and the flat panel filter 8 have sufficient installation space. This ensures that the lens will not interfere with the base and housing during installation, and guarantees that the equipment process for the industrial lens is simple.

[0070] In one specific embodiment, optionally, the telephoto industrial lens satisfies the following condition: |Dis|≤0.1%; where Dis is the distortion of the telephoto industrial lens.

[0071] As those skilled in the art will understand, distortion describes the deformation between the actual image plane and the ideal image plane. Controlling distortion can control the geometry of the image and also change the image's data quality. In this embodiment, by limiting the lens's distortion data, a high-quality, low-distortion imaging effect can be obtained.

[0072] Based on the same concept described above, this utility model provides three different specific embodiments, and their optical power relationship and related physical optical parameter design ranges are shown in Table 1:

[0073] Table 1. Optical power relationship of each lens and design values ​​of related physical and optical parameters in the three embodiments.

[0074]

[0075] In Embodiment 1 of this utility model, reference is made to... Figure 1 Knowing the structure, shape, and location of each component in the system is crucial. As shown in the figure, the optical lens consists of seven glass spherical lenses. The fourth lens 4 and the fifth lens 5 are cemented together. The image-side surface of the first lens 1 is convex, the image-side surface of the second lens 2 is concave, the object-side surface of the fifth lens 5 is convex, and the image-side surface of the seventh lens 7 is concave. A flat plate filter 8 is also positioned along the object plane to the image plane, located on the image-side surface of the seventh lens 7. The flat plate filter 8 protects the photosensitive chip in the imaging sensor. Figure 1 The design parameters of each lens in the telephoto industrial lens of Embodiment 1 are shown in Table 2:

[0076] Table 2. Design values ​​of optical physical parameters for each lens in the industrial lens of Example 1

[0077]

[0078] The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "STO" represents the lens aperture; "IMA" represents the image plane; radius of curvature represents the curvature of the corresponding lens surface, with positive values ​​indicating the surface bends towards the image plane and negative values ​​indicating the surface bends towards the object plane. "INF" indicates the surface is flat with an infinite radius of curvature; thickness represents the central axial distance between the current surface and the next surface; refractive index represents the ability of the material between the current and next surfaces to deflect light; a blank space indicates the current location is air with a refractive index of 1. The technical specifications achieved by the lens shown in Embodiment 1 are shown in Table 3.

[0079] Table 3. Specific performance parameters of the industrial lens in Example 1.

[0080]

[0081] Figure 2 for Figure 1 The diagram shows the axial aberration of a telephoto industrial lens. The vertical direction represents the normalized aperture, with 0 indicating on the optical axis, and the vertical vertex representing the maximum pupil radius. The horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system's imaging, derived from... Figure 2 It can be seen that the axial aberrations at different wavelengths are all controlled within a reasonable range, indicating that the spherical aberration of this industrial lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications.

[0082] Figure 3 for Figure 1 The diagram shown is a transverse chromatic aberration diagram of a telephoto industrial lens. The vertical direction represents the normalized field of view, with 0 indicating on the optical axis. The dominant wavelength is 546 nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (µm). Figure 3 As can be seen, the transverse chromatic aberration of different wavelengths is controlled within a good range, indicating that the transverse chromatic aberration of this industrial lens is well controlled in industrial applications and can meet the requirements of wide spectrum applications.

[0083] Figure 4 for Figure 1 The diagram shown illustrates the field curvature and distortion of a telephoto industrial lens. In the left coordinate system, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height (unitless). T represents meridion, and S represents arc distortion. In the right coordinate system, the horizontal axis represents the magnitude of the distortion in %; the vertical axis represents the normalized image height (unitless). Figure 4 It can be seen that the lens provided in this embodiment effectively controls field curvature and distortion, that is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small.

[0084] Figure 5 This is a structural schematic diagram of a telephoto industrial lens provided in Embodiment 2 of this utility model, for reference. Figure 5 In the second embodiment of this utility model, reference is made to Figure 5Knowing the structure, shape, and location of each component in the system is crucial. As shown in the figure, the optical lens consists of seven glass spherical lenses. The second lens 2 and the third lens 3 are cemented together. The image-side surface of the first lens 1 is flat, the image-side surface of the second lens 2 is convex, the object-side surface of the fifth lens 5 is concave, and the image-side surface of the seventh lens 7 is convex. A flat plate filter 8 is also positioned along the object plane to the image plane, located on the image-side surface of the seventh lens 7. The flat plate filter 8 protects the photosensitive chip in the imaging sensor. Figure 5 The design parameters of each lens in the telephoto industrial lens of Embodiment 2 are shown in Table 4:

[0085] Table 4. Design values ​​of optical physical parameters for each lens in the industrial lens of Example 2

[0086]

[0087] The surface numbers in Table 4 are assigned according to the surface sequence of each lens. "STO" represents the lens aperture; "IMA" represents the image plane; radius of curvature represents the curvature of the corresponding lens surface, with positive values ​​indicating the surface bends towards the image plane and negative values ​​indicating the surface bends towards the object plane. "INF" indicates the surface is flat with an infinite radius of curvature; thickness represents the central axial distance between the current surface and the next surface; refractive index represents the ability of the material between the current and next surfaces to deflect light; a blank space indicates the current location is air with a refractive index of 1. The technical specifications achieved by the lens shown in Embodiment 2 are shown in Table 5.

[0088] Table 5 Specific performance parameters of the industrial lens in Example 2

[0089]

[0090] Figure 6 for Figure 5 The diagram shows the axial aberration of a telephoto industrial lens. The vertical direction represents the normalized aperture, with 0 indicating on the optical axis, and the vertical vertex representing the maximum pupil radius. The horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system's imaging, derived from... Figure 6 It can be seen that the axial aberrations at different wavelengths are all controlled within a reasonable range, indicating that the spherical aberration of this industrial lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications.

[0091] Figure 7 for Figure 5The diagram shown is a transverse chromatic aberration diagram of a telephoto industrial lens. The vertical direction represents the normalized field of view, with 0 indicating on the optical axis. The dominant wavelength is 546 nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (µm). Figure 7 As can be seen, the transverse chromatic aberration of different wavelengths is controlled within a good range, indicating that the transverse chromatic aberration of this industrial lens is well controlled in industrial applications and can meet the requirements of wide spectrum applications.

[0092] Figure 8 for Figure 5 The diagram shown illustrates the field curvature and distortion of a telephoto industrial lens. In the left coordinate system, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height (unitless). T represents meridion, and S represents arc distortion. In the right coordinate system, the horizontal axis represents the magnitude of the distortion in %; the vertical axis represents the normalized image height (unitless). Figure 8 It can be seen that the lens provided in this embodiment effectively controls field curvature and distortion, that is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small.

[0093] Figure 9 This is a structural schematic diagram of a telephoto industrial lens provided in Embodiment 3 of this utility model, for reference. Figure 9 In the third embodiment of this utility model, reference is made to Figure 9 The structure, shape, and location of each component in the system are known, which is crucial for the system. As shown in the figure, the optical lens consists of seven glass spherical lenses. The image-side surface of the first lens 1 and the second lens 2 is concave, the object-side surface of the fifth lens 5 is convex, and the image-side surface of the seventh lens 7 is concave. A flat plate filter 8 is also positioned along the object plane to the image plane, located on the image-side surface of the seventh lens 7. The flat plate filter 8 protects the photosensitive chip in the imaging sensor. Figure 9 The design parameters of each lens in the telephoto industrial lens of Embodiment 3 are shown in Table 6:

[0094] Table 6. Design values ​​of optical physical parameters for each lens in the industrial lens of Example 3

[0095]

[0096] The surface numbers in Table 6 are assigned according to the surface sequence of each lens. "STO" represents the lens stop; "IMA" represents the image plane; radius of curvature represents the curvature of the corresponding lens surface—a positive value indicates the surface curves towards the image plane, and a negative value indicates it curves towards the object plane. "INF" indicates the surface is flat with an infinite radius of curvature; thickness represents the central axial distance between the current surface and the next surface; refractive index represents the ability of the material between the current and next surfaces to deflect light; a blank space indicates the current location is air with a refractive index of 1. The technical specifications achieved by the lens shown in Embodiment 3 are shown in Table 7.

[0097] Table 7 Specific performance parameters of the industrial lens in Example 3

[0098]

[0099] Figure 10 for Figure 9 The diagram shows the axial aberration of a telephoto industrial lens. The vertical direction represents the normalized aperture, with 0 indicating on the optical axis, and the vertical vertex representing the maximum pupil radius. The horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system's imaging, derived from... Figure 10 It can be seen that the axial aberrations at different wavelengths are all controlled within a reasonable range, indicating that the spherical aberration of this industrial lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications.

[0100] Figure 11 for Figure 9 The diagram shown is a transverse chromatic aberration diagram of a telephoto industrial lens. The vertical direction represents the normalized field of view, with 0 indicating on the optical axis. The dominant wavelength is 546 nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (µm). Figure 11 As can be seen, the transverse chromatic aberration of different wavelengths is controlled within a good range, indicating that the transverse chromatic aberration of this industrial lens is well controlled in industrial applications and can meet the requirements of wide spectrum applications.

[0101] Figure 12 for Figure 9 The diagram shown illustrates the field curvature and distortion of a telephoto industrial lens. In the left coordinate system, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height (unitless). T represents meridion, and S represents arc distortion. In the right coordinate system, the horizontal axis represents the magnitude of the distortion in %; the vertical axis represents the normalized image height (unitless). Figure 12 It can be seen that the lens provided in this embodiment effectively controls field curvature and distortion, that is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small.

[0102] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A telephoto industrial lens, characterized in that, It includes a first lens with positive optical power, a second lens with positive optical power, a third lens with negative optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with positive optical power, and a seventh lens with negative optical power, arranged sequentially from the object side to the image side along the optical axis. The first lens through the seventh lens satisfy the following conditions: 0.638 < φ1 / φ < 0.98; 0.370 < φ2 / φ < 1.139; -2.137 < φ3 / φ < -1.595; -1.609 < φ4 / φ < -0.762; 0.503 < φ5 / φ < 1.817; 1.064 < φ6 / φ < 1.536; -0.900 < φ7 / φ < -0.026; Wherein, φ1, φ2, φ3, φ4, φ5, φ6, and φ7 are the optical powers of the first lens to the seventh lens, respectively, and φ is the total optical power of the telephoto industrial lens.

2. The telephoto industrial lens according to claim 1, characterized in that, The object-side surface of the first lens is convex, and the image-side surface is convex, planar, or concave. The object-side surface of the second lens is convex, and the image-side surface is either convex or concave. The object-side surface of the third lens is concave, and the image-side surface is also concave. The fourth lens has a concave side surface and a concave side surface; The object side of the fifth lens is convex or concave, and the image side is convex. The object-side surface of the sixth lens is convex, and the image-side surface is also convex. The object side of the seventh lens is concave, and the image side is either convex or concave.

3. The telephoto industrial lens according to claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all glass spherical lenses.

4. The telephoto industrial lens according to claim 1, characterized in that, The surfaces of the second lens and the third lens adjacent to each other are cemented together to form a cemented lens group.

5. The telephoto industrial lens according to claim 4, characterized in that, The second lens and the third lens satisfy the following conditions: 1.55≤Nd2≤1.61; 55≤Vd2≤85; 1.56≤Nd3≤1.71; 25≤Vd3≤35.9; Wherein, Nd2 and Nd3 are the refractive indices of the second lens and the third lens, respectively, and Vd2 and Vd3 are the Abbe numbers of the second lens and the third lens, respectively.

6. The telephoto industrial lens according to claim 1, characterized in that, The surfaces of the fourth lens and the fifth lens adjacent to each other are cemented together to form a cemented lens group.

7. The telephoto industrial lens according to claim 6, characterized in that, The fourth lens and the fifth lens satisfy the following conditions: 1.46≤Nd⁴≤1.65; 20≤Vd⁴≤35.7; 1.79≤Nd5≤1.95; 31.9≤Vd5≤80; Wherein, Nd4 and Nd5 are the refractive indices of the fourth lens and the fifth lens, respectively, and Vd4 and Vd5 are the Abbe numbers of the fourth lens and the fifth lens, respectively.

8. The telephoto industrial lens according to claim 1, characterized in that, It also includes an aperture stop, which is located between the third lens and the fourth lens.

9. The telephoto industrial lens according to claim 1, characterized in that, The telephoto industrial lens meets the following condition: 2.765≤EFL / BFL≤3.267; Wherein, EFL is the focal length of the telephoto industrial lens, and BFL is the back focal length of the telephoto industrial lens.

10. The telephoto industrial lens according to claim 1, characterized in that, The telephoto industrial lens meets the following condition: |Dis|≤0.1%; Where Dis represents the distortion of the telephoto industrial lens.

Images