Line scanning industrial lens
By employing a fourteen-lens design and a floating focusing method, the problems of aberration correction difficulty and inconsistent image quality in line scan lenses at short focal lengths have been solved, resulting in a line scan lens with low distortion, large target area, and high resolution, thus meeting the market demand for a wide field of view.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2026-03-31
AI Technical Summary
Line scan lenses suffer from problems such as difficulty in aberration correction, inconsistent image quality, and severe edge field distortion when used with short focal lengths and wide working distances. In particular, with floating focus, it is difficult to achieve high-quality imaging at different object distances.
It adopts a fourteen-lens design, including one fixed group, two moving groups and three fixed groups. Through the combination of lens materials and optical power distribution, combined with floating focusing method, it can achieve low distortion and high resolution imaging of large target area within the working distance of 200mm to 1000mm.
At short focal lengths, distortion was reduced to less than 1%, and image quality reached MTF 71pl/mm > 0.3, ensuring high consistent image quality at different object distances and reducing lens size and cost.
Smart Images
Figure CN121763546A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lens technology, and more particularly to a line scan industrial lens. Background Technology
[0002] In the field of line scan machine vision for industrial lenses, there is a demand for short focal lengths and wide working distances. Under the premise of a constant target area, the shorter the focal length, the larger the field of view. When there are requirements for small distortion and a wide working distance, the difficulty of aberration correction increases dramatically.
[0003] Floating focus, as the mainstream focusing method for line scan lenses, has the advantages of low cost, short focusing travel, and compact overall lens structure. However, the image quality at different object distances still deteriorates significantly compared to the optimal object distance. Therefore, maintaining consistent high-quality imaging at different object distances is a major challenge for line scan lenses today.
[0004] Furthermore, as the market demand for the field of view of line scan lenses increases and the focal length becomes shorter, distortion and field curvature at the edge of the field of view have become problems that line scan lenses must solve. Summary of the Invention
[0005] This invention provides a line scan industrial lens. By combining lens materials and rationally allocating the optical power of each lens, and employing a floating focusing method, a high-resolution line scan lens design that can balance low distortion and large target area can be achieved within a working distance of 200mm to 1000mm. The system focal length is 31mm, the maximum aperture is F4, the optimal object distance is 600mm, the distortion is <1%, and the imaging quality can reach a modulation transfer function MTF 71pl / mm > 0.3.
[0006] According to one aspect of the present invention, a line scan industrial lens is provided, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, and a fourteenth lens arranged sequentially along the optical axis from the object side to the image side.
[0007] The first to the seventh lenses form a fixed group, the eighth to the twelfth lenses form two moving groups, and the thirteenth and fourteenth lenses form three fixed groups. The two moving groups reciprocate along the optical axis to achieve the change of object distance of the line scanning industrial lens.
[0008] The line scan industrial lens meets the following conditions:
[0009] 4.3600≤TTL / EFL≤4.4400;
[0010] 2.2000≤TTL / DM≤2.3900;
[0011] 81.8100°≤FOV≤82.9500°;
[0012] Wherein, TTL represents the distance from the object side to the image plane of the first lens, DM represents the maximum effective aperture of the lens, EFL represents the overall focal length of the line scan industrial lens, and FOV represents the field of view of the line scan industrial lens.
[0013] Optionally, the optical power of the first fixed group, the second moving group, and the third fixed group satisfies:
[0014] 0.0030≤ΦZ1≤0.0080;
[0015] 0.0250≤ΦZ2≤0.0260;
[0016] -0.0260≤ΦZ3≤-0.0230;
[0017] -1.1100≤ΦZ2 / ΦZ3≤-1.0000;
[0018] Wherein ΦZ1 represents the optical power of the first fixed group, ΦZ2 represents the optical power of the second moving group, and ΦZ3 represents the optical power of the third fixed group.
[0019] Optionally, the first lens has negative optical power, the second lens has negative optical power, the third lens has negative optical power, the fourth lens has positive optical power, the fifth lens has positive optical power, the sixth lens has negative optical power, the seventh lens has positive optical power, the eighth lens has positive optical power, the ninth lens has negative optical power, the tenth lens has negative optical angle, the eleventh lens has positive optical power, the twelfth lens has positive optical power, the thirteenth lens has positive optical power, and the fourteenth lens has negative optical power.
[0020] Optionally, the refractive indices of the first lens to the second lens satisfy:
[0021] 1.6990≤Nd.MIN(L1, L2);
[0022] -0.0220≤ΦL1-L2≤-0.0210;
[0023] Where ΦL1-L2 represents the total optical power from the first lens to the second lens, and Nd.MIN(L1, L2) represents the minimum refractive index of the lens from the first lens to the second lens.
[0024] Optionally, the Abbe numbers of the tenth lens to the eleventh lens satisfy:
[0025] 1.6000≤Vd11 / Vd10;
[0026] Wherein Vd10 represents the Abbe number of the tenth lens, and Vd11 represents the Abbe number of the eleventh lens.
[0027] Optionally, an aperture stop is also included, which is located between the ninth lens and the tenth lens.
[0028] Optionally, the sixth to ninth lenses and the tenth to thirteenth lenses form a Gaussian symmetric structure centered on the aperture stop;
[0029] The optical distortion of the line scan industrial lens satisfies:
[0030] 0 ≤ |MAX.DS| ≤ 1%;
[0031] Where |MAX.DS| represents the maximum optical distortion of the line scan industrial lens.
[0032] Optionally, the fourteenth lens satisfies:
[0033] -0.5540≤Φ14×TH≤-0.5300;
[0034] 2.0400≤Nd14;
[0035] Where Φ14 represents the optical power of the fourteenth lens, TH represents the on-axis air gap between the thirteenth and fourteenth lenses, and Nd14 represents the refractive index of the fourteenth lens.
[0036] Optionally, the first lens to the fourteenth lens are all glass spherical lenses.
[0037] Optionally, the working distance of the line scan industrial lens is 200mm to 1000mm, and the focal length is 31mm.
[0038] The line-scanning industrial lens provided in this invention includes fourteen lenses arranged sequentially from the object side to the image side along the optical axis. The first to seventh lenses form a fixed group, the eighth to twelfth lenses form two moving groups, and the thirteenth and fourteenth lenses form three fixed groups. The two moving groups reciprocate along the optical axis to achieve changes in the object distance of the line-scanning industrial lens. By combining lens materials and rationally allocating the optical power of each lens, and employing a floating focusing method, a high-resolution line-scanning lens design that balances low distortion and a large target area can be achieved within a working distance of 200mm to 1000mm. The system focal length is 31mm, the maximum aperture is F4, the optimal object distance is 600mm, |distortion| < 1%, and the imaging quality can reach MTF 71pl / mm > 0.3.
[0039] 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
[0040] 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.
[0041] Figure 1 This is a schematic diagram of the structure of a line scan industrial lens provided in an embodiment of the present invention;
[0042] Figure 2 For the corresponding Figure 1 A fan-shaped pattern of a line-scan industrial lens;
[0043] Figure 3 For the corresponding Figure 1 Field curvature distortion curve of a line scan industrial lens;
[0044] Figure 4 For the corresponding Figure 1 MTF curve of a line scan industrial lens at a 600mm object distance;
[0045] Figure 5 For the corresponding Figure 1 MTF curve of a line scan industrial lens at a 200mm object distance;
[0046] Figure 6 For the corresponding Figure 1 MTF curve of a line scan industrial lens at a 1000mm object distance;
[0047] Figure 7 This is a schematic diagram of another line-scan industrial lens provided in an embodiment of the present invention;
[0048] Figure 8 For the corresponding Figure 7 A fan-shaped pattern of a line-scan industrial lens;
[0049] Figure 9 For the corresponding Figure 7 Field curvature distortion curve of a line scan industrial lens;
[0050] Figure 10 For the corresponding Figure 7 MTF curve of a line scan industrial lens at a 600mm object distance;
[0051] Figure 11 For the corresponding Figure 7 MTF curve of a line scan industrial lens at a 200mm object distance;
[0052] Figure 12 For the corresponding Figure 7 MTF curve of a line scan industrial lens at a 1000mm object distance;
[0053] Figure 13 This is a schematic diagram of the structure of another line-scan industrial lens provided in an embodiment of the present invention;
[0054] Figure 14 For the corresponding Figure 13 A fan-shaped pattern of a line-scan industrial lens;
[0055] Figure 15 For the corresponding Figure 13 Field curvature distortion curve of a line scan industrial lens;
[0056] Figure 16 For the corresponding Figure 13 MTF curve of a line scan industrial lens at a 600mm object distance;
[0057] Figure 17 For the corresponding Figure 13 MTF curve of a line scan industrial lens at a 200mm object distance;
[0058] Figure 18 For the corresponding Figure 13 MTF curve of a line scan industrial lens at a 1000mm object distance. Detailed Implementation
[0059] 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.
[0060] 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 orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0061] Figure 1 This is a schematic diagram of the structure of a line scan industrial lens provided in an embodiment of the present invention, with reference to... Figure 1 ,from Figure 1 Knowing the structure and composition of each lens in the lens, as well as the shape and position of each component, is crucial for the system. The line-scanning industrial lens provided in this embodiment includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107, an eighth lens 201, a ninth lens 202, a tenth lens 203, an eleventh lens 204, a twelfth lens 205, a thirteenth lens 301, and a fourteenth lens 302 arranged sequentially along the optical axis from the object side to the image side. The first to seventh lenses 101 form a fixed group 100, the eighth to twelfth lenses 201 form two moving groups 200, and the thirteenth and fourteenth lenses 301 form three fixed groups 300. The two moving groups 200 reciprocate along the optical axis to achieve changes in the object distance of the line-scanning industrial lens.
[0062] Line scan industrial lenses must meet the following conditions:
[0063] 4.3600≤TTL / EFL≤4.4400;
[0064] 2.2000≤TTL / DM≤2.3900;
[0065] 81.8100°≤FOV≤82.9500°;
[0066] Wherein, TTL represents the distance from the object side to the image plane of the first lens 101, DM represents the maximum effective aperture of the lens, EFL represents the overall focal length of the line scan industrial lens, and FOV represents the field of view of the line scan industrial lens.
[0067] Optionally, the first lens 101 to the fourteenth lens 302 are all glass spherical lenses. While maintaining a constant image height, a shorter total length results in a smaller maximum effective aperture and a correspondingly smaller volume. Satisfying 2.2000≤TTL / DM≤2.3900 allows for a large image height while reducing volume. For large-area line-scan industrial lenses, they are typically bulky and require many lenses for aberration correction. However, this embodiment of the invention uses only 14 spherical glass lenses to achieve high-quality imaging on ultra-large target surfaces, minimizing cost and volume while keeping the total length within 137.01mm and ensuring clear resolution.
[0068] This invention provides an industrial lens capable of achieving a focal length of 31mm, optimal object distance support of 200mm to 1000mm, TTL ≤ 137.01mm, maximum effective lens diameter ≤ 57.52mm, maximum target surface area support of 57.4mm, supported field of view greater than or equal to 81.81°, and maximum distortion ≤ 1%. Optionally, the first lens 101, the second lens 102, and the third lens 103 have negative optical power. The fourth lens 104 has positive optical power, the fifth lens 105 has positive optical power, the sixth lens 106 has negative optical power, the seventh lens 107 has positive optical power, the eighth lens 201 has positive optical power, the ninth lens 202 has negative optical power, the tenth lens 203 has negative optical angle, the eleventh lens 204 has positive optical power, the twelfth lens 205 has positive optical power, the thirteenth lens 301 has positive optical power, and the fourteenth lens 302 has negative optical power.
[0069] As can be understood, optical power is the reciprocal of focal length and characterizes the ability of an optical system to deflect light. The larger the absolute value of optical power, the stronger the ability to bend light; the smaller the absolute value of optical power, the weaker the ability to bend light. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. By designing the relationship between the optical powers of various lenses, high-performance line-scan lenses can be designed.
[0070] Optionally, the optical power of one fixed group 100, two moving groups 200, and three fixed groups 300 satisfies:
[0071] 0.0030≤ΦZ1≤0.0080;
[0072] 0.0250≤ΦZ2≤0.0260;
[0073] -0.0260≤ΦZ3≤-0.0230;
[0074] -1.1100≤ΦZ2 / ΦZ3≤-1.0000;
[0075] Wherein ΦZ1 represents the optical power of a fixed group of 100, ΦZ2 represents the optical power of a moving group of 200, and ΦZ3 represents the optical power of a fixed group of 300.
[0076] By setting up one fixed group 100, two moving groups 200, and three fixed groups 300 to meet the above range, the optical performance of the lens can be better realized.
[0077] Optionally, the refractive indices of the first lens 101 to the second lens 102 satisfy:
[0078] 1.6990≤Nd.MIN(L1, L2);
[0079] -0.0220≤ΦL1-L2≤-0.0210;
[0080] Where ΦL1-L2 represents the total optical power from the first lens 101 to the second lens 102, and Nd.MIN(L1, L2) represents the minimum refractive index of the lens from the first lens 101 to the second lens 102.
[0081] The first lens 101 and the second lens 102 are the two frontmost lenses of the lens. Satisfying the above relationship helps to achieve a large field of view design, making the incident light at a large angle tend to flatten more quickly. While ensuring the maximum range of information collected from the object under test, the number of lenses is reduced, making the lens lighter.
[0082] Optionally, the Abbe numbers of the tenth lens 203 to the eleventh lens 204 satisfy:
[0083] 1.6000≤Vd11 / Vd10;
[0084] Where Vd10 represents the Abbe number of the tenth lens 203, and Vd11 represents the Abbe number of the eleventh lens 204.
[0085] The tenth lens 203 and the eleventh lens 204 are located near the aperture stop. The positive and negative lens groups that meet the above conditions have a large difference in Abbe number, which can effectively correct the chromatic aberration of the system, improve the imaging quality, and make the detection results clearer and more accurate.
[0086] Optional, continue to refer to Figure 1 The line scan industrial lens also includes an aperture 400, which is located between the ninth lens 202 and the tenth lens 203.
[0087] Optionally, the sixth lens 106 to the ninth lens 202 and the tenth lens 203 to the thirteenth lens 301 form a Gaussian symmetrical structure centered on the aperture 400; the optical distortion of the line scan industrial lens satisfies:
[0088] 0 ≤ |MAX.DS| ≤ 1%;
[0089] Where |MAX.DS| represents the maximum optical distortion of a line scan industrial lens.
[0090] By designing the sixth lens 106 to the thirteenth lens 301 to form a Gaussian symmetrical structure centered on the aperture 400, system distortion can be effectively corrected, the influence of imaging distortion can be reduced, and the maximum value of system optical distortion can always be controlled within ±1%, so as to better reflect the actual value of the measured object and make the data obtained by industrial testing more accurate.
[0091] Optionally, the fourteenth lens 302 satisfies:
[0092] -0.5540≤Φ14×TH≤-0.5300;
[0093] 2.0400≤Nd14;
[0094] Where Φ14 represents the optical power of the fourteenth lens 302, TH represents the on-axis air gap between the thirteenth lens 301 and the fourteenth lens 302, and Nd14 represents the refractive index of the fourteenth lens 302.
[0095] By setting the fourteenth lens 302 to be a high refractive index material and having a negative optical power, and placing it close to the image plane, a Pittswan field lens can be formed. By controlling the on-axis air gap between the thirteenth lens 301 and the fourteenth lens 302, the field curvature of the system can be effectively corrected, and a small degree of actual image plane curvature can be guaranteed at different object distances.
[0096] For example, Table 1 shows the corresponding... Figure 1 Specific parameters of the line scan industrial lens:
[0097] Table 1. Specific parameters of line scan industrial lenses.
[0098] Example 1 lower limit upper limit TTL / EFL 4.4381 4.3600 4.4400 TTL / DM 2.3822 2.2000 2.3900 EFL 30.8701 30.8600 31.3600 TTL 137.0050 136.9900 137.0100 FOV 82.9483 81.8100 82.9500 Nd.MIN(L1-L2) 1.7008 1.6990 1.7100 ΦL1-L2 -0.0217 -0.0220 -0.0210 Vd11 / Vd10 2.5949 1.6000 2.6000 Φ14×TH -0.5515 -0.5540 -0.5300 Nd14 2.0587 2.0400 2.0600 |MAX.DS| 0.5143％ 0.0000％ 0.9800％ ΦZ1 0.0038 0.0030 0.0080 ΦZ2 0.0252 0.0250 0.0260 ΦZ3 -0.0251 -0.0260 -0.0230 ΦZ2 / ΦZ3 -1.0047 -1.1100 -1.0000
[0099] Table 2 shows the corresponding... Figure 1 Parameter data of each lens
[0100]
[0101]
[0102] The surface numbers are assigned according to the order of the lens surfaces; the radius of curvature indicates the degree of curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane; the thickness indicates the central axial distance between the current surface and the next surface; the refractive index indicates the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number indicates 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. OBJ represents the object plane, IMA represents the image plane, 12, 16, and 20 are cemented surfaces, and 14 and 24 are virtual surfaces. When the 14th surface is spaced at -0.368mm and the 24th surface at 0.368mm, the focusing distance can reach 200mm; when the 14th surface is spaced at 1.431mm and the 24th surface at -1.431mm, the focusing distance can reach 1000mm.
[0103] Figure 2 For the corresponding Figure 1 The fan plot of a line-scan industrial lens is one of the most commonly used evaluation methods in modern optical design. The horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. Ideally, the fan plot is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis corresponding to this line-scan curve represents the maximum dispersion range of the beam on the ideal image plane. The fan plot can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figure 2 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 is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.
[0104] Figure 3 For the corresponding Figure 1 Field curvature distortion curve of a line scan industrial lens. 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 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; the vertical axis represents the normalized image height, which has no unit; from Figure 3 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with optical distortion less than ±0.6%.
[0105] Figure 4 For the corresponding Figure 1The MTF curve of the line scan industrial lens at a 600mm object distance is shown, where the horizontal axis represents spatial frequency in line pairs / mm, and the vertical axis represents OTF modulus. All MTF orientation plots have the same coordinates. The lens provided in this embodiment has an image quality of 71pl / mm from the center field of view to the edge field of view that is higher than 0.3MTF, and the imaging has excellent resolution.
[0106] Figure 5 For the corresponding Figure 1 The MTF curve of the line scan industrial lens at a 200mm object distance shows that the image quality of the lens provided in this embodiment is higher than 0.3MTF from the center field of view to the edge field of view, with a resolution of 71pl / mm.
[0107] Figure 6 For the corresponding Figure 1 The MTF curve of the line scan industrial lens at a distance of 1000mm shows that the image quality of the lens from the center field of view to the edge field of view is 71pl / mm, which is higher than 0.3MTF, and the imaging has excellent resolution.
[0108] Figure 7 This is a schematic diagram of another line-scan industrial lens provided in an embodiment of the present invention. Table 3 shows the corresponding structure. Figure 7 Specific parameters of the line scan industrial lens:
[0109] Table 3. Specific parameters of line scan industrial lenses
[0110] Example 2 lower limit upper limit TTL / EFL 4.3736 4.3600 4.4400 TTL / DM 2.2021 2.2000 2.3900 EFL 31.3237 30.8600 31.3600 TTL 136.9990 136.9900 137.0100 FOV 81.8587 81.8100 82.9500 Nd.MIN(L1-L2) 1.7007 1.6990 1.7100 ΦL1-L2 -0.0216 -0.0220 -0.0210 Vd11 / Vd10 1.6004 1.6000 2.6000 Φ14×TH -0.5535 -0.5540 -0.5300 Nd14 2.0448 2.0400 2.0600 |MAX.DS| 0.9153％ 0.0000％ 0.9800％ ΦZ1 0.0056 0.0030 0.0080 ΦZ2 0.0256 0.0250 0.0260 ΦZ3 -0.0231 -0.0260 -0.0230 ΦZ2 / ΦZ3 -1.1093 -1.1100 -1.0000
[0111] Table 4 shows the corresponding... Figure 7 Parameter data of each lens
[0112]
[0113]
[0114] The surface numbers are assigned according to the order of the lens surfaces; the radius of curvature indicates the degree of curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane; the thickness indicates the central axial distance between the current surface and the next surface; the refractive index indicates the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number indicates 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. OBJ represents the object plane, IMA represents the image plane, 17 and 21 are cemented surfaces, and 15 and 25 are virtual surfaces. When the 15th surface is spaced at -0.318mm and the 25th surface at 0.318mm, the focusing distance can reach 200mm; when the 15th surface is spaced at 1.601mm and the 25th surface at -1.601mm, the focusing distance can reach 1000mm.
[0115] Figure 8 For the corresponding Figure 7 The fan plot of a line-scan industrial lens is one of the most commonly used evaluation methods in modern optical design. The horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. Ideally, the fan plot is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis corresponding to this line-scan curve represents the maximum dispersion range of the beam on the ideal image plane. The fan plot can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figure 8 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 is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.
[0116] Figure 9 For the corresponding Figure 7 Field curvature distortion curve of a line scan industrial lens. Figure 9 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 9 It can be seen that the 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; the vertical axis represents the normalized image height, which has no unit; from Figure 9 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with optical distortion less than ±1%.
[0117] Figure 10 For the corresponding Figure 7The MTF curve of the line scan industrial lens at a 600mm object distance shows that the image quality of the lens provided in this embodiment is higher than 0.3MTF from the center field of view to the edge field of view, with a resolution of 71pl / mm.
[0118] Figure 11 For the corresponding Figure 7 The MTF curve of the line scan industrial lens at a 200mm object distance shows that the image quality of the lens provided in this embodiment is higher than 0.3MTF from the center field of view to the edge field of view, with a resolution of 71pl / mm.
[0119] Figure 12 For the corresponding Figure 7 The MTF curve of the line scan industrial lens at a distance of 1000mm shows that the image quality of the lens from the center field of view to the edge field of view is 71pl / mm, which is higher than 0.3MTF, and the imaging has excellent resolution.
[0120] Figure 13 This is a schematic diagram of another line-scan industrial lens provided in an embodiment of the present invention. Table 5 shows the corresponding structure. Figure 13 Specific parameters of the line scan industrial lens:
[0121] Table 5. Specific parameters of line scan industrial lenses.
[0122] Example 3 lower limit upper limit TTL / EFL 4.3692 4.3600 4.4400 TTL / DM 2.2276 2.2000 2.3900 EFL 31.3563 30.8600 31.3600 TTL 137.0030 136.9900 137.0100 FOV 81.8171 81.8100 82.9500 Nd.MIN(L1-L2) 1.6991 1.6990 1.7100 ΦL1-L2 -0.0217 -0.0220 -0.0210 Vd11 / Vd10 1.7977 1.6000 2.6000 Φ14×TH -0.5303 -0.5540 -0.5300 Nd14 2.0557 2.0400 2.0600 |MAX.DS| 0.9783％ 0.0000％ 0.9800％ ΦZ1 0.0077 0.0030 0.0080 ΦZ2 0.0252 0.0250 0.0260 ΦZ3 -0.0238 -0.0260 -0.0230 ΦZ2 / ΦZ3 -1.0593 -1.1100 -1.0000
[0123] Table 6 shows the corresponding... Figure 13 Parameter data of each lens
[0124]
[0125]
[0126] The surface numbers are assigned according to the order of the lens surfaces; the radius of curvature indicates the degree of curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane; the thickness indicates the central axial distance between the current surface and the next surface; the refractive index indicates the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the Abbe number indicates 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. OBJ represents the object plane, IMA represents the image plane, 16 and 20 are cemented surfaces, and 14 and 24 are virtual surfaces. When the 14th surface is spaced at -0.694mm and the 24th surface at 0.694mm, the focusing distance can reach 200mm; when the 14th surface is spaced at 1.203mm and the 24th surface at -1.203mm, the focusing distance can reach 1000mm.
[0127] Figure 14 For the corresponding Figure 13 The fan plot of a line-scan industrial lens is one of the most commonly used evaluation methods in modern optical design. The horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. Ideally, the fan plot is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. The interval on the vertical axis corresponding to this line-scan curve represents the maximum dispersion range of the beam on the ideal image plane. The fan plot can reflect not only monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figure 14 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 is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.
[0128] Figure 15 For the corresponding Figure 13 Field curvature distortion curve of a line scan industrial lens. Figure 15 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 15 It can be seen that the 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; the vertical axis represents the normalized image height, which has no unit; from Figure 15 As can be seen, the distortion of the lens provided in this embodiment has been well corrected, with optical distortion less than ±1%.
[0129] Figure 16 For the corresponding Figure 13 The MTF curve of the line scan industrial lens at a 600mm object distance shows that the image quality of the lens provided in this embodiment is higher than 0.3MTF from the center field of view to the edge field of view, with a resolution of 71pl / mm.
[0130] Figure 17 For the corresponding Figure 13 The MTF curve of the line scan industrial lens at a 200mm object distance shows that the image quality of the lens provided in this embodiment is higher than 0.3MTF from the center field of view to the edge field of view, with a resolution of 71pl / mm.
[0131] Figure 18 For the corresponding Figure 13 The MTF curve of the line scan industrial lens at a distance of 1000mm shows that the image quality of the lens from the center field of view to the edge field of view is 71pl / mm, which is higher than 0.3MTF, and the imaging has excellent resolution.
[0132] 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 line scan industrial lens, characterized in that, It includes the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, tenth lens, eleventh lens, twelfth lens, thirteenth lens and fourteenth lens arranged sequentially along the optical axis from the object side to the image side; The first to the seventh lenses form a fixed group, the eighth to the twelfth lenses form two moving groups, and the thirteenth and fourteenth lenses form three fixed groups. The two moving groups reciprocate along the optical axis to achieve the change of object distance of the line scanning industrial lens. The line scan industrial lens meets the following conditions: 4.3600≤TTL / EFL≤4.4400; 2.2000≤TTL / DM≤2.3900; 81.8100°≤FOV≤82.9500°; Wherein, TTL represents the distance from the object side to the image plane of the first lens, DM represents the maximum effective aperture of the lens, EFL represents the overall focal length of the line scan industrial lens, and FOV represents the field of view of the line scan industrial lens.
2. The line scan industrial lens according to claim 1, characterized in that, The optical power of the first fixed group, the second moving group, and the third fixed group satisfies: 0.0030≤ΦZ1≤0.0080; 0.0250≤ΦZ2≤0.0260; -0.0260≤ΦZ3≤-0.0230; -1.1100≤ΦZ2 / ΦZ3≤-1.0000; Wherein ΦZ1 represents the optical power of the first fixed group, ΦZ2 represents the optical power of the second moving group, and ΦZ3 represents the optical power of the third fixed group.
3. The line scan industrial lens according to claim 1, characterized in that, The first lens has negative optical power, the second lens has negative optical power, the third lens has negative optical power, the fourth lens has positive optical power, the fifth lens has positive optical power, the sixth lens has negative optical power, the seventh lens has positive optical power, the eighth lens has positive optical power, the ninth lens has negative optical power, the tenth lens has negative optical angle, the eleventh lens has positive optical power, the twelfth lens has positive optical power, the thirteenth lens has positive optical power, and the fourteenth lens has negative optical power.
4. The line scan industrial lens according to claim 1, characterized in that, The refractive indices of the first lens and the second lens satisfy the following: 1.6990≤Nd.MIN(L1, L2); -0.0220≤ΦL1-L2≤-0.0210; Where ΦL1-L2 represents the total optical power from the first lens to the second lens, and Nd.MIN(L1, L2) represents the minimum refractive index of the lens from the first lens to the second lens.
5. The line scan industrial lens according to claim 1, characterized in that, The Abbe numbers of the tenth lens to the eleventh lens satisfy: 1.6000≤Vd11 / Vd10; Wherein Vd10 represents the Abbe number of the tenth lens, and Vd11 represents the Abbe number of the eleventh lens.
6. The line scan industrial lens according to claim 1, characterized in that, It also includes an aperture stop, which is located between the ninth lens and the tenth lens.
7. The line scan industrial lens according to claim 6, characterized in that, The sixth to ninth lenses and the tenth to thirteenth lenses form a Gaussian symmetric structure centered on the aperture stop; The optical distortion of the line scan industrial lens satisfies: 0 ≤ |MAX.DS| ≤ 1%; Where |MAX.DS| represents the maximum optical distortion of the line scan industrial lens.
8. The line scan industrial lens according to claim 1, characterized in that, The fourteenth lens satisfies: -0.5540≤Φ14×TH≤-0.5300; 2.0400≤Nd14; Where Φ14 represents the optical power of the fourteenth lens, TH represents the on-axis air gap between the thirteenth and fourteenth lenses, and Nd14 represents the refractive index of the fourteenth lens.
9. The line scan industrial lens according to claim 1, characterized in that, The first lens to the fourteenth lens are all glass spherical lenses.
10. The line scan industrial lens according to claim 1, characterized in that, The working distance of the line scan industrial lens is 200mm to 1000mm, and the focal length is 31mm.