A long focal length industrial lens

Abstract

The application discloses a long-focus industrial lens. The long-focus industrial lens is arranged with a first lens group, a diaphragm, a second lens group and a third lens group arranged in sequence along an optical axis from an object plane to an image plane; the first lens group has positive refractive power, the second lens group has negative refractive power, and the third lens group has positive refractive power; and the refractive power of the first lens group, the second lens group and the third lens group is limited to meet a certain proportion range, so that the refractive power can be more reasonably shared, the correction of spherical aberration is facilitated, the incidence angle and the emergence angle of light are reduced without affecting the refractive power of the first lens group, the sagittal aberration is reduced, the correction of field curvature, astigmatism, distortion and chromatic aberration and other aberrations is realized, and finally a long-focus industrial lens scheme with low aberration and high resolution is realized.

Description

Technical Field

[0001] This invention relates to the technical field of optical systems, and more particularly to a telephoto industrial lens. Background Technology

[0002] With the development of the times, machine vision has been applied in various fields, greatly improving the production efficiency of various industries. Replacing the highly complex manual vision with machine vision effectively safeguards human interests and safety. Machine vision technology can be used in special environments where manual labor is ineffective. However, modern industrial technology demands increasingly higher detection accuracy, driving the development of lenses towards higher image quality, and telephoto lenses can further improve detection accuracy.

[0003] Traditional industrial lenses with long focal lengths offer higher magnification, allowing for the distribution of more pixels across the image plane for the same-sized object, thus resulting in higher analytical accuracy. However, telephoto lenses typically come with greater chromatic aberration, leading to reduced image quality and blurry images. Summary of the Invention

[0004] This invention provides a telephoto industrial lens to achieve a low-aberration, high-resolution telephoto industrial lens solution.

[0005] In a first aspect, the present invention provides a telephoto industrial lens, comprising a first lens group, an aperture stop, a second lens group, and a third lens group arranged sequentially along the optical axis from the object plane to the image plane;

[0006] The first lens group has positive optical power, the second lens group has negative optical power, and the third lens group has positive optical power.

[0007] The first lens group, the second lens group, and the third lens group satisfy the following conditions:

[0008] 0.015≤ΦZ1≤0.025;

[0009] -0.035≤ΦZ2≤-0.025;

[0010] 0.010≤ΦZ3≤0.020;

[0011] Wherein, ΦZ1 is the optical power of the first lens group, ΦZ2 is the optical power of the second lens group, and ΦZ3 is the optical power of the third lens group.

[0012] Optionally, the first lens group includes a first lens and a second lens, the second lens group includes a third lens and a fourth lens, and the third lens group includes a fifth lens.

[0013] Optionally, the opposing surfaces of the first and second lenses are cemented together to form a first cemented lens group; the opposing surfaces of the third and fourth lenses are cemented together to form a second cemented lens group.

[0014] Optionally, the first lens group includes a first lens, the second lens group includes a second lens, a third lens, and a fourth lens, and the third lens group includes a fifth lens.

[0015] Optionally, the opposing surfaces of the second and third lenses are cemented together to form a third cemented lens group; or,

[0016] The opposing surfaces of the second, third, and fourth lenses are cemented together to form a fourth cemented lens group.

[0017] Optionally, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all glass spherical lenses.

[0018] Optionally, the fifth lens satisfies the following condition:

[0019] 1.0000≤Φ5 / Φ≤1.2300;

[0020] 1.82≤Nd5≤1.94;

[0021] Wherein, Φ5 is the optical power of the fifth lens, Φ is the optical power of the telephoto industrial lens, and Nd5 is the refractive index of the fifth lens.

[0022] Optionally, the second lens group includes at least two lenses, with the lens closer to the object side satisfying the following condition: VdZ2L1 / VdZ2L2≥2.69;

[0023] Wherein, VdZ2L1 is the Abbe number of the first lens in the second lens group closest to the aperture, and VdZ2L2 is the Abbe number of the second lens in the second lens group closest to the aperture.

[0024] Optionally, the first lens group and the telephoto industrial lens satisfy the following conditions:

[0025] 1.4200≤ΦZ1 / Φ≤1.6700;

[0026] MIN.RI ≥ 98.95%;

[0027] Where Φ represents the optical power of the telephoto industrial lens, and MIN.RI represents the minimum relative illumination of the telephoto industrial lens.

[0028] Optionally, telephoto industrial lenses must meet the following conditions:

[0029] 1.1800≤TTL / EFL≤1.2000;

[0030] 3.5000≤TTL / DM≤3.6100;

[0031] 0.225≤|β|≤0.240;

[0032] Where TTL is the total optical length from the front end of the first lens group to the image plane, EFL is the focal length of the telephoto industrial lens, DM is the maximum effective aperture of the telephoto industrial lens, and β is the transverse magnification of the telephoto industrial lens.

[0033] The technical solution of this invention, by setting a first lens group, an aperture, a second lens group, and a third lens group arranged sequentially along the optical axis from the object plane to the image plane; the first lens group has positive optical power, the second lens group has negative optical power, and the third lens group has positive optical power; and limiting the optical power of the first lens group, the second lens group, and the third lens group to meet a certain range, can more reasonably distribute the optical power, which is beneficial to the correction of spherical aberration. At the same time, without affecting the optical power of the first lens group, it reduces the incident angle and exit angle of light, reduces transverse aberration, and realizes the correction of aberrations such as field curvature astigmatism, distortion, and chromatic aberration, ultimately achieving a low-aberration, high-resolution telephoto industrial lens solution.

[0034] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 1 of the present invention;

[0037] Figure 2 for Figure 1 The ray fan diagram of the telephoto industrial lens in Embodiment 1 is shown.

[0038] Figure 3 for Figure 1 Field curvature distortion diagram of the telephoto industrial lens in Embodiment 1 shown;

[0039] Figure 4 for Figure 1 The transverse chromatic aberration diagram of the telephoto industrial lens in Embodiment 1 is shown.

[0040] Figure 5This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 2 of the present invention;

[0041] Figure 6 for Figure 5 The ray fan diagram of the telephoto industrial lens in Embodiment 2 is shown;

[0042] Figure 7 for Figure 5 Field curvature distortion diagram of the telephoto industrial lens in Example 2 shown;

[0043] Figure 8 for Figure 5 The transverse chromatic aberration diagram of the telephoto industrial lens in Example 2 is shown.

[0044] Figure 9 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 3 of the present invention;

[0045] Figure 10 for Figure 9 The ray fan diagram of the telephoto industrial lens in Embodiment 3 is shown;

[0046] Figure 11 for Figure 9 Field curvature distortion diagram of the telephoto industrial lens in Example 3 shown;

[0047] Figure 12 for Figure 9 The vertical chromatic aberration diagram of the telephoto industrial lens in Example 3 is shown. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.

[0050] Figure 1 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 1 of the present invention, with reference to... Figure 1A telephoto industrial lens comprises a first lens group 1, an aperture 2, a second lens group 3, and a third lens group 4 arranged sequentially along the optical axis from the object plane to the image plane (IMA); the first lens group 1 has positive optical power, the second lens group 3 has negative optical power, and the third lens group 4 has positive optical power; the first lens group 1, the second lens group 3, and the third lens group 4 satisfy the following conditions:

[0051] 0.015≤ΦZ1≤0.025;

[0052] -0.035≤ΦZ2≤-0.025;

[0053] 0.010≤ΦZ3≤0.020;

[0054] Wherein, ΦZ1 is the optical power of the first lens group, ΦZ2 is the optical power of the second lens group, and ΦZ3 is the optical power of the third lens group.

[0055] The optical power of a lens is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, characterizing the optical system's ability to deflect light. A larger absolute value of the optical power indicates a stronger ability to bend light, while a smaller absolute value indicates a weaker ability. When the optical power is positive, the refraction of light is converging; when the optical power is negative, the refraction of light is diverging. In this embodiment, all lenses can be housed in a single lens barrel (…). Figure 1 Within the lens (not shown), a first lens group 1 and a third lens group 4 are configured with positive optical power, while a second lens group 3 has negative optical power. These lens groups can converge or diverge light rays; that is, by coordinating the optical power of each lens group, the optical power can be rationally allocated to correct spherical aberration. Furthermore, the first lens group 1 is used to converge the object's light rays, the second lens group 3 is used to correct chromatic aberration, and the third lens group 4 is used to correct distortion, thus achieving a long-focus industrial lens with low distortion and low chromatic aberration.

[0056] Furthermore, setting the first lens group 1, the second lens group 3, and the third lens group 4 to satisfy the aforementioned ratio of optical power for each lens group essentially defines the specific roles they play in the overall optical system of the lens. These three lens groups can be used to converge or diverge light. In other words, by reasonably setting the positive and negative values ​​and specific ranges of the optical power of each lens group, the relative beam converging or diverging effects of each lens group within the entire lens are effectively limited. The aforementioned range of optical power for each lens group is a relationship obtained through reasonable experimentation. Under this optical power relationship, the entire lens can achieve imaging performance with a large target area and low chromatic aberration. It also facilitates the correction and balancing of aberrations such as distortion, spherical aberration, and field curvature astigmatism, especially effectively reducing the impact of distortion, improving imaging resolution, and ensuring the imaging quality of the IMA (Integrated Motion Area).

[0057] Furthermore, in this embodiment, an aperture stop 2 is provided between the first lens group 1 and the second lens group 3. The aperture stop 2 in the optical system is used to limit the beam size, determining the amount of light entering the photosensitive element through the lens, i.e., controlling the light transmission of the lens. In other words, the aperture stop 2 directly determines the aperture size of the telephoto industrial lens. In the telephoto industrial lens provided by this embodiment, the aperture stop 2 can be positioned between the first lens group 1 and the second lens group 3, utilizing the waist position of the entire optical system to control the light transmission. This ensures the amount of light passing through the aperture stop 2 while effectively limiting the aperture size of the optical system, thus ensuring image brightness. In addition, the aperture stop 2 can block off-axis light rays, effectively reducing off-axis aberrations and ensuring image sharpness.

[0058] The technical solution of this invention involves setting up a first lens group, an aperture stop, a second lens group, and a third lens group arranged sequentially along the optical axis from the object plane to the image plane (IMA). The first lens group has positive optical power, the second lens group has negative optical power, and the third lens group has positive optical power. Furthermore, the optical power of the first, second, and third lens groups is limited to a certain range, which allows for a more reasonable distribution of optical power, which is beneficial for the correction of spherical aberration. At the same time, without affecting the optical power of the first lens group, the incident and exit angles of light are reduced, and transverse aberration is decreased. This achieves the correction of aberrations such as field curvature astigmatism, distortion, and chromatic aberration, ultimately realizing a low-aberration, high-resolution telephoto industrial lens solution.

[0059] Based on the above embodiments, further optional references can be made. Figure 1 The first lens group 1 includes a first lens 10 and a second lens 20; the second lens group 3 includes a third lens 30 and a fourth lens 40; and the third lens group 4 includes a fifth lens 50. Optionally, the opposing surfaces of the first lens 10 and the second lens 20 are cemented together to form a first cemented lens group; and the opposing surfaces of the third lens 30 and the fourth lens 40 are cemented together to form a second cemented lens group. The cemented lens group can reduce the inter-lens spacing, appropriately correct chromatic aberration, and improve field curvature and coma, thereby further optimizing image quality.

[0060] In another optional embodiment, the first lens group 1 includes a first lens 10, the second lens group 3 includes a second lens 20, a third lens 30, and a fourth lens 40, and the third lens group 4 includes a fifth lens 50. Further optionally, the opposing surfaces of the second lens 20 and the third lens 30 are cemented together to form a third cemented lens group; or, the opposing surfaces of the second lens 20, the third lens 30, and the fourth lens 40 are cemented together to form a fourth cemented lens group. This reduces the inter-lens spacing, allows for appropriate correction of chromatic aberration, and improves field curvature and coma, thereby further optimizing image quality.

[0061] Optionally, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 are all glass spherical lenses. By utilizing the properties of glass, the sensitivity of imaging to temperature is reduced, the degree of lens deformation at different temperatures is minimized, and clear imaging is ensured even in high and low temperature environments.

[0062] Optionally, the fifth lens 50 satisfies the following condition:

[0063] 1.0000≤Φ5 / Φ≤1.2300;

[0064] 1.82≤Nd5≤1.94;

[0065] Wherein, Φ5 is the optical power of the fifth lens 50, Φ is the optical power of the telephoto industrial lens, and Nd5 is the refractive index of the fifth lens 50.

[0066] Refractive index represents the lens's ability to refract incident light; a higher refractive index means a stronger ability to refract incident light. Distortion represents the degree of distortion of the image formed by an optical system relative to the object itself; optical distortion refers to the degree of deformation calculated theoretically in optics. Using the above combination helps to better converge the chromatic aberration-corrected edge field of view rays onto the image plane (IMA), correcting edge field of view distortion and field curvature, and consistently controlling the maximum value of lens optical distortion within ±0.05%, thus better reflecting the actual value of the measured image.

[0067] Optionally, the second lens group 3 includes at least two lenses, with the lens closer to the object side satisfying the following condition: VdZ2L1 / VdZ2L2≥2.69;

[0068] Wherein, VdZ2L1 is the Abbe number of the first lens in the second lens group 3 closest to the aperture 2, and VdZ2L2 is the Abbe number of the second lens in the second lens group 3 closest to the aperture 2.

[0069] The Abbe number represents the index of the medium's dispersion capability; a higher Abbe number indicates less dispersion. By setting the Abbe numbers of the two lenses in the second lens group 3 closest to the aperture 2, a significant difference in the Abbe numbers between the two lenses can correct chromatic aberration in the lens's optical system, improve image quality, and make the detection results clearer and more accurate. For example, when the second lens group 3 includes a third lens 30 and a fourth lens 40, the above relationship can be the Abbe number relationship between the third lens 30 and the fourth lens 40; when the second lens group 3 includes a second lens 20, a third lens 30, and a fourth lens 40, the above relationship can be the Abbe number relationship between the second lens 20 and the third lens 30, and the specific relationship can be determined according to the actual situation.

[0070] Optionally, the first lens group 1 and the telephoto industrial lens satisfy the following conditions:

[0071] 1.4200≤ΦZ1 / Φ≤1.6700;

[0072] MIN.RI ≥ 98.95%;

[0073] Where Φ represents the optical power of the telephoto industrial lens, and MIN.RI represents the minimum relative illumination of the telephoto industrial lens.

[0074] Illuminance refers to the intensity of light shining on the surface of an object, while relative illuminance is the ratio between the illuminance at different coordinate points on a plane and the illuminance at the center point. This combination helps in designing telephoto lenses, allowing for a smoother convergence of the object-side light angle, maximizing luminous flux, and minimizing the loss of relative illuminance.

[0075] Optionally, telephoto industrial lenses must meet the following conditions:

[0076] 1.1800≤TTL / EFL≤1.2000;

[0077] 3.5000≤TTL / DM≤3.6100;

[0078] 0.225≤|β|≤0.240;

[0079] Where TTL is the total optical length from the front end of the first lens group 1 to the image plane IMA, EFL is the focal length of the telephoto industrial lens, DM is the maximum effective aperture of the telephoto industrial lens, and β is the transverse magnification of the telephoto industrial lens.

[0080] Specifically, TTL is the total optical length from the front end of the first lens group 1 to the image plane IMA, DM is the maximum effective aperture of the lens. While maintaining a constant image height, a shorter total optical length TTL results in a smaller maximum effective aperture DM, leading to a smaller lens size. Satisfying the above conditions allows for a large image height while reducing size. EFL represents the overall focal length of the lens. Telephoto lenses are typically longer and require more lenses for chromatic aberration correction. |β| represents the absolute value of the transverse magnification. When the image plane IMA is consistent, a higher transverse magnification allows for the distribution of more pixels on the image plane IMA for imaging of objects of the same size, thus resulting in higher analysis accuracy. Thus, this invention can be achieved using only 5 spherical glass lenses, keeping the total length within 89.55mm while achieving a transverse magnification exceeding 0.225, minimizing cost and size while ensuring clear image resolution.

[0081] Based on the same inventive concept, this invention provides three different specific embodiments, the optical power relationship and related physical and optical parameter design ranges of which are shown in Table 1:

[0082] Table 1. Optical power relationships and related physical and optical parameter design ranges of long-focal-length industrial lenses in three embodiments of the present invention.

[0083]

[0084] In Embodiment 1 of the present invention, as Figure 1 As shown, the first lens group 1 includes a first lens 10 and a second lens 20; the second lens group 3 includes a third lens 30 and a fourth lens 40; and the third lens group 4 includes a fifth lens 50. The opposing surfaces of the first lens 10 and the second lens 20 are cemented together to form a first cemented lens group; the opposing surfaces of the third lens 30 and the fourth lens 40 are cemented together to form a second cemented lens group. The parameter design values ​​for each lens in the telephoto industrial lens of this embodiment are shown in Table 2.

[0085] Table 2. Design values ​​for each lens in the telephoto industrial lens of Example 1

[0086]

[0087] The surface numbers in Table 2 are assigned according to the surface sequence of each lens, where "1" represents the front surface of the first lens 10, "2" represents the rear surface of the first lens 10, and so on. The radius of curvature represents the degree of curvature of the lens surface; a positive value indicates that the surface bends towards the image plane (IMA), and a negative value indicates that the surface bends towards the object plane. 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 surface and the next surface to deflect light; a blank space indicates that the current position is air, with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. Half-aperture indicates half the aperture size of the current surface. When the 9th surface interval is 52.328 mm, focusing can reach an object distance of 250 mm; when the 9th surface interval is 32.802 mm, focusing can reach an object distance of 500 mm.

[0088] Figure 2 for Figure 1 The ray fan diagram of the telephoto industrial lens in Embodiment 1 is shown below, with reference to... Figure 2 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane (IMA). The interval on the vertical axis of the curve corresponds to the maximum dispersion range of the beam on the ideal image plane. The fan diagram not only reflects monochromatic aberrations of different wavelengths but also represents the magnitude of transverse chromatic aberration. Figure 2It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength in the telephoto industrial lens is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of this telephoto industrial lens is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0089] Figure 3 for Figure 1 The field curvature distortion diagram of the telephoto industrial lens in Embodiment 1 is shown below, with reference to... Figure 3 As shown, Figure 3 In the left-hand coordinate system, the horizontal coordinate represents the magnitude of the field curvature in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; Figure 3 It can be seen that the telephoto industrial lens provided in this embodiment effectively controls field curvature, meaning that during imaging, the difference in image quality between the center and the periphery is small, resulting in good consistency; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage, while the vertical axis represents the normalized image height, which has no unit; from Figure 3 It can be seen that the distortion of the telephoto industrial lens provided in this embodiment has been well corrected, with optical distortion less than ±0.04%.

[0090] Figure 4 for Figure 1 The transverse chromatic aberration diagram of the telephoto industrial lens in Embodiment 1 is shown for reference. Figure 4 It is known that the telephoto industrial lens provided by this invention has a chromatic aberration smaller than the Airy disk size from the center field of view to the edge field of view in the 449nm-680nm band, ensuring clear imaging quality.

[0091] Figure 5 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 2 of the present invention, with reference to... Figure 5 As shown, in Embodiment 2 of the present invention, the first lens group 1 includes a first lens 10, the second lens group 3 includes a second lens 20, a third lens 30 and a fourth lens 40, and the third lens group 4 includes a fifth lens 50. The opposing surfaces of the second lens 20 and the third lens 30 are glued together to form a third cemented lens group, which is different from the lens structure in the first lens group 1 and the second lens group 3 in Embodiment 1, and also different from the cemented lens group in the second lens group 3. Figure 5 The optical power relationship and related physical and optical parameter design ranges of the telephoto industrial lens in Embodiment 2 are shown in Table 1. The design values ​​of one parameter for each lens in this telephoto industrial lens are shown in Table 3.

[0092] Table 3. Design values ​​for each lens in the telephoto industrial lens of Example 2.

[0093]

[0094] The surface numbers in Table 3 are assigned according to the surface sequence of each lens, where "1" represents the front surface of the first lens 10, "2" represents the rear surface of the first lens 10, and so on. The radius of curvature represents the degree of curvature of the lens surface; a positive value indicates that the surface bends towards the image plane (IMA), and a negative value indicates that the surface bends towards the object plane. 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 surface and the next surface to deflect light; a blank space indicates that the current position is air, with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. Half-aperture indicates half the aperture size of the current surface. When the 10th surface interval is 51.220 mm, focusing can reach an object distance of 250 mm; when the 10th surface interval is 32.458 mm, focusing can reach an object distance of 500 mm.

[0095] Figure 6 for Figure 5 The ray fan diagram of the telephoto industrial lens in Embodiment 2 is shown below, for reference only. Figure 6 As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane (IMA). The interval on the vertical axis of the curve corresponds to the maximum dispersion range of the beam on the ideal image plane. The fan diagram not only reflects monochromatic aberrations of different wavelengths but also represents the magnitude of transverse chromatic aberration. Figure 6 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength in the telephoto industrial lens is well corrected. At the same time, there is no obvious dispersion in each wavelength, indicating that the chromatic aberration of the telephoto industrial lens is also well corrected, thus ensuring that the optical system can achieve high-resolution imaging requirements.

[0096] Figure 7 for Figure 5 The field curvature distortion diagram of the telephoto industrial lens in Example 2 is shown below, for reference. Figure 7 As shown, Figure 7 In the left-hand coordinate system, the horizontal coordinate represents the magnitude of the field curvature in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; Figure 7 It can be seen that the telephoto industrial lens provided in this embodiment 2 effectively controls field curvature, that is, during imaging, the difference between the image quality in the center and the image quality at the periphery is small, and the consistency is good; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion, in %; the vertical coordinate represents the normalized image height, which has no unit; from Figure 7 It can be seen that the distortion of the telephoto industrial lens provided in this embodiment 2 has been well corrected, with optical distortion less than ±0.025%.

[0097] Figure 8 for Figure 5 The transverse chromatic aberration diagram of the telephoto industrial lens in Embodiment 2 is shown below, for reference. Figure 8 It is known that the telephoto industrial lens provided by this invention has a chromatic aberration smaller than the Airy disk size from the center field of view to the edge field of view in the 449nm-680nm band, ensuring clear imaging quality.

[0098] Figure 9 This is a schematic diagram of the structure of a telephoto industrial lens provided in Embodiment 3 of the present invention, with reference to... Figure 9 As shown, in Embodiment 3 of the present invention, the first lens group 1 includes a first lens 10, the second lens group 3 includes a second lens 20, a third lens 30, and a fourth lens 40, and the third lens group 4 includes a fifth lens 50. The opposing surfaces of the second lens 20, the third lens 30, and the fourth lens 40 are cemented together to form a fourth cemented lens group. This differs from the lens structure in the first lens group 1 and the second lens group 3 in Embodiment 1, and also differs from the cemented lens group in the second lens group 3 in Embodiment 2, specifically the distance between the third lens 30 and the fourth lens 40 in Embodiment 2. Furthermore, Figure 9 The optical power relationship and related physical and optical parameter design ranges of the telephoto industrial lens in Embodiment 3 are shown in Table 1. The design values ​​of one parameter for each lens in this telephoto industrial lens are shown in Table 4.

[0099] Table 4. Design values ​​for each lens in the telephoto industrial lens of Example 3.

[0100]

[0101] The surface numbers in Table 4 are assigned according to the surface sequence of each lens, where "1" represents the front surface of the first lens 10, "2" represents the rear surface of the first lens 10, and so on. The radius of curvature represents the degree of curvature of the lens surface; a positive value indicates that the surface bends towards the image plane (IMA), and a negative value indicates that the surface bends towards the object plane. 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 surface and the next surface to deflect light; a blank space indicates that the current position is air, with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. Half-aperture indicates half the aperture size of the current surface. When the 9th surface interval is 54.917 mm, focusing can reach an object distance of 250 mm; when the 9th surface interval is 34.521 mm, focusing can reach an object distance of 500 mm.

[0102] Figure 10 for Figure 9 The ray fan diagram of the telephoto industrial lens in Embodiment 3 is shown below, for reference. Figure 10As shown, the horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane (IMA). The interval on the vertical axis of the curve corresponds to the maximum dispersion range of the beam on the ideal image plane. The fan diagram not only reflects monochromatic aberrations of different wavelengths but also represents the magnitude of transverse chromatic aberration. Figure 10 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength in the telephoto industrial lens is well corrected. At the same time, there is no obvious dispersion in each wavelength, indicating that the chromatic aberration of the telephoto industrial lens is also well corrected, thus ensuring that the optical system can achieve high-resolution imaging requirements.

[0103] Figure 11 for Figure 9 The field curvature distortion diagram of the telephoto industrial lens in Example 3 is shown below, for reference. Figure 11 As shown, Figure 11 In the left-hand coordinate system, the horizontal coordinate represents the magnitude of the field curvature in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the sagitta; Figure 11 It can be seen that the telephoto industrial lens provided in this embodiment three effectively controls field curvature, that is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small, and the consistency is good; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion, in %; the vertical coordinate represents the normalized image height, which has no unit; from Figure 11 It can be seen that the distortion of the telephoto industrial lens provided in this embodiment 3 has been well corrected, with optical distortion less than ±0.045%.

[0104] Figure 12 for Figure 9 The transverse chromatic aberration diagram of the telephoto industrial lens in Embodiment 3 is shown below, for reference. Figure 12 It is known that the telephoto industrial lens provided by this invention has a chromatic aberration smaller than the Airy disk size from the center field of view to the edge field of view in the 449nm-680nm band, ensuring clear imaging quality.

[0105] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0106] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A telephoto industrial lens, characterized in that, It includes a first lens group, an aperture, a second lens group, and a third lens group arranged sequentially along the optical axis from the object plane to the image plane; the total number of lenses is 5. The first lens group has positive optical power, the second lens group has negative optical power, and the third lens group has positive optical power; The first lens group, the second lens group, and the third lens group satisfy the following conditions: 0.015≤ΦZ1≤0.025; -0.035≤ΦZ2≤-0.025; 0.010≤ΦZ3≤0.020; Wherein, ΦZ1 is the optical power of the first lens group, ΦZ2 is the optical power of the second lens group, and ΦZ3 is the optical power of the third lens group; The first lens group includes a first lens and a second lens, the second lens group includes a third lens and a fourth lens, and the third lens group includes a fifth lens; or, the first lens group includes a first lens, the second lens group includes a second lens, a third lens and a fourth lens, and the third lens group includes a fifth lens; The telephoto industrial lens meets the following conditions: 1.1800≤TTL / EFL≤1.2000; 3.5000≤TTL / DM≤3.6100; 0.225≤|β|≤0.240； Wherein, TTL is the total optical length from the front end of the first lens group to the image plane, EFL is the focal length of the telephoto industrial lens, DM is the maximum effective aperture of the telephoto industrial lens, and β is the transverse magnification of the telephoto industrial lens.

2. The telephoto industrial lens according to claim 1, characterized in that, The opposing surfaces of the first lens and the second lens are glued together to form a first cemented lens group; the opposing surfaces of the third lens and the fourth lens are glued together to form a second cemented lens group.

3. The telephoto industrial lens according to claim 1, characterized in that, The opposing surfaces of the second lens and the third lens are cemented together to form a third cemented lens assembly; or, The opposing surfaces of the second lens, the third lens, and the fourth lens are cemented together to form a fourth cemented lens group.

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

5. The telephoto industrial lens according to claim 1, characterized in that, The fifth lens satisfies the following condition: 1.0000≤Φ5 / Φ≤1.2300; 1.82≤Nd5≤1.94; Wherein, Φ5 is the optical power of the fifth lens, Φ is the optical power of the telephoto industrial lens, and Nd5 is the refractive index of the fifth lens.

6. The telephoto industrial lens according to claim 1, characterized in that, The second lens group includes at least two lenses, and the lens closer to the object side satisfies the following condition: VdZ2L1 / VdZ2L2≥2.69; Wherein, VdZ2L1 is the Abbe number of the first lens in the second lens group closest to the aperture, and VdZ2L2 is the Abbe number of the second lens in the second lens group closest to the aperture.

7. The telephoto industrial lens according to claim 1, characterized in that, The first lens group and the telephoto industrial lens satisfy the following conditions: 1.4200≤ΦZ1 / Φ≤1.6700; MIN.RI ≥ 98.95%; Wherein, Φ is the optical power of the telephoto industrial lens, and MIN.RI is the minimum relative illumination of the telephoto industrial lens.

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