Industrial lens

Abstract

The invention discloses an industrial lens. The industrial lens comprises a first lens group, a second lens group and a third lens group, the positions of the first lens group and the third lens group are fixed, and the position of the second lens group is floatable; the first lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens; the second lens group comprises a ninth lens; and the third lens group comprises a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens. The second lens group moves along the optical axis to realize focusing of different object distances, and the first lens group and the third lens group are fixed, so that the influence of focusing to different object distances on resolution can be reduced, and the balance of image quality of each working distance is ensured. And the number of the lenses in each lens group is reasonably set, so that the industrial lens with high image quality imaging performance is facilitated.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical devices, and in particular to an industrial lens. Background Art

[0002] Short-focus industrial lenses have important applications in the field of precision measurement and detection. Their high resolution and low distortion can accurately capture changes in tiny objects. In the manufacturing industry, they are widely used in automated assembly and quality inspection to ensure the consistency of product quality. In the field of security monitoring, they can be used for close-range monitoring and identification, which helps to improve the accuracy and reliability of monitoring. In medical equipment, they are mostly used in microscopes, endoscopes and other equipment to help with accurate diagnosis. Even in emerging application areas, such as virtual reality and augmented reality technologies, they provide a wider perspective and a more realistic experience.

[0003] As the market demands for short-focus industrial lenses become increasingly higher, industrial lenses that achieve high-quality imaging performance have become a research hotspot. Summary of the invention

[0004] The present invention provides an industrial lens, which realizes an industrial lens with high image quality imaging performance.

[0005] An embodiment of the present invention provides an industrial lens, comprising a first lens group, a second lens group, and a third lens group arranged in sequence from an object plane to an image plane along an optical axis; the positions of the first lens group and the third lens group are fixed, and the position of the second lens group can float along the optical axis;

[0006] The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens; the second lens group includes a ninth lens; and the third lens group includes a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens.

[0007] Optionally, the total optical length of the industrial lens is TTL, the focal length is EFL, the maximum effective aperture is DM, the image plane size is IM, the aperture number is FNO, and the field of view angle is FOV;

[0008] Among them, 17.5200≤TTL / EFL≤17.6500, 2.0400≤TTL / DM≤2.0600,

[0009] 3.0500≤IM / FNO≤3.0700, FOV≥96.3700.

[0010] Optionally, the optical focal power of the first lens is negative; the optical focal power of the second lens is negative; the optical focal power of the third lens is negative; the optical focal power of the fourth lens is positive; the fifth lens and the sixth lens are glued together to form a first glued lens, and the optical focal power of the first glued lens is negative; the seventh lens and the eighth lens are glued together to form a second glued lens, and the optical focal power of the second glued lens is positive; the optical focal power of the ninth lens is positive; the tenth lens and the eleventh lens are glued together to form a third glued lens, and the optical focal power of the third glued lens is positive; the twelfth lens, the thirteenth lens and the fourteenth lens are glued together to form a fourth glued lens, and the optical focal power of the fourth glued lens is negative; the optical focal power of the fifteenth lens is positive.

[0011] Optionally, the optical power of the fifth lens is Φ5, and the refractive index is ND5; the optical power of the sixth lens is Φ6, and the refractive index is ND6;

[0012] Among them, -1.7900≤Φ5 / Φ6≤-1.1300, 1.2700≤ND6 / ND5≤1.3600.

[0013] Optionally, the Abbe number of the seventh lens is VD7, the Abbe number of the eighth lens is VD8, the Abbe number of the thirteenth lens is VD13, and the Abbe number of the fourteenth lens is VD14;

[0014] Among them, 1.9100≤|VD7 / VD8|≤2.9500, 4.6800≤VD13 / VD14≤5.3000.

[0015] Optionally, the total optical length of the industrial lens is TTL, the focal length is EFL, the maximum effective aperture is DM, the image plane size is IM, the working F number is FNO, and the field of view angle is FOV;

[0016] Among them, 17.5200≤TTL / EFL≤17.6500, 2.0400≤TTL / DM≤2.0600,

[0017] 3.0500≤IM / FNO≤3.0700, FOV≥96.3700°.

[0018] Optionally, the refractive index Nd1 of the first lens satisfies Nd1≥1.9300.

[0019] Optionally, the industrial lens further includes an aperture, and the aperture is arranged in the optical path between the eleventh lens and the twelfth lens;

[0020] The focal power of the lens group formed by the ninth lens, the tenth lens and the eleventh lens is ΦZ1, the focal power of the lens group formed by the twelfth lens, the thirteenth lens and the fourteenth lens is ΦZ2, and the maximum optical distortion of the industrial lens is DISG.MAX;

[0021] Among them, -0.9600≤ΦZ1 / ΦZ2≤-0.7500; 0≤|DISG.MAX|≤0.500%.

[0022] Optionally, the shape factor of the fourth lens is ξ4, and the minimum value of the full-field relative illumination of the industrial lens is RI.MIN;

[0023] Among them, 6.0400≤|ξ4|≤12.1400; 84.2000%≤RI.MIN.

[0024] Optionally, the first lens includes a first object-side surface close to the object plane and a first image-side surface close to the image plane, the first object-side surface is a convex surface, and the first image-side surface is a concave surface;

[0025] The second lens comprises a second object-side surface close to the object plane and a second image-side surface close to the image plane, the second object-side surface is a convex surface, and the second image-side surface is a concave surface;

[0026] The third lens comprises a third object-side surface close to the object plane and a third image-side surface close to the image plane, the third object-side surface is a concave surface, and the third image-side surface is a concave surface;

[0027] The fourth lens comprises a fourth object-side surface close to the object plane and a fourth image-side surface close to the image plane, the fourth object-side surface is a concave surface, and the fourth image-side surface is a convex surface;

[0028] The fifth lens comprises a fifth object-side surface close to the object plane and a fifth image-side surface close to the image plane, the fifth object-side surface is a concave surface, and the fifth image-side surface is a convex surface;

[0029] The sixth lens comprises a sixth object-side surface close to the object plane and a sixth image-side surface close to the image plane, the sixth object-side surface is a concave surface, and the sixth image-side surface is a convex surface;

[0030] The seventh lens comprises a seventh object-side surface close to the object plane and a seventh image-side surface close to the image plane, the seventh object-side surface is a concave surface or a convex surface, and the seventh image-side surface is a concave surface or a convex surface;

[0031] The eighth lens comprises an eighth object-side surface close to the object plane and an eighth image-side surface close to the image plane, the eighth object-side surface is a convex surface or a concave surface, and the eighth image-side surface is a convex surface;

[0032] The ninth lens comprises a ninth object-side surface close to the object plane and a ninth image-side surface close to the image plane, the ninth object-side surface is a convex surface, and the ninth image-side surface is a concave surface or a convex surface;

[0033] The tenth lens comprises a tenth object-side surface close to the object plane and a tenth image-side surface close to the image plane, the tenth object-side surface is a convex surface, and the tenth image-side surface is a concave surface;

[0034] The eleventh lens comprises an eleventh object-side surface close to the object plane and an eleventh image-side surface close to the image plane, the eleventh object-side surface is a convex surface, and the eleventh image-side surface is a concave surface or a convex surface;

[0035] The twelfth lens comprises a twelfth object-side surface close to the object plane and a twelfth image-side surface close to the image plane, the twelfth object-side surface is a convex surface, and the twelfth image-side surface is a concave surface;

[0036] The thirteenth lens comprises a thirteenth object-side surface close to the object plane and a thirteenth image-side surface close to the image plane, the thirteenth object-side surface is a convex surface, and the thirteenth image-side surface is a convex surface;

[0037] The fourteenth lens comprises a fourteenth object-side surface close to the object plane and a fourteenth image-side surface close to the image plane, the fourteenth object-side surface is a concave surface, and the fourteenth image-side surface is a concave surface or a convex surface;

[0038] The fifteenth lens includes a fifteenth object-side surface close to the object plane and a fifteenth image-side surface close to the image plane. The fifteenth object-side surface is a convex surface, and the fifteenth image-side surface is a convex surface.

[0039] Optionally, the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens, the thirteenth lens, and the fourteenth lens are all glass spherical lenses;

[0040] The second lens and the fifteenth lens are both glass aspherical lenses.

[0041] The industrial lens provided by the embodiment of the present invention is provided with a second lens group that can float along the optical axis, so as to ensure that focusing can be achieved at different working distances and clear imaging can be achieved at different working object distances; and the second lens group only includes the ninth lens, that is, only one lens is used for floating focusing, the number of floating focusing lenses is small, and the lens stability is high. Furthermore, the first lens group and the third lens group are fixed, so that the influence of focusing at different object distances on the resolution can be reduced, ensuring that the image quality at each working distance is balanced, and realizing an industrial lens with high image quality imaging performance.

[0042] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 This is a schematic structural diagram of an industrial lens provided by Embodiment 1 of the present invention at an optimal object distance;

[0045] Figure 2 Schematic diagram of Ray Fan of an industrial lens at an optimal object distance provided by Embodiment 1 of the present invention;

[0046] Figure 3 1 is a schematic diagram of a field curvature distortion curve of an industrial lens at an optimal object distance provided by the first embodiment of the present invention;

[0047] Figure 4 1 is a schematic diagram of an MTF curve of an industrial lens at an optimal object distance provided by the first embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of axial chromatic aberration of an industrial lens at an optimal object distance provided by the first embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of vertical axis chromatic aberration of an industrial lens at an optimal object distance provided by the first embodiment of the present invention;

[0050] Figure 7 This is a schematic diagram of the structure of an industrial lens at an optimal object distance provided by the second embodiment of the present invention;

[0051] Figure 8Schematic diagram of Ray Fan of an industrial lens at an optimal object distance provided by Embodiment 2 of the present invention;

[0052] Fig. 9 This is a schematic diagram of a field curvature distortion curve of an industrial lens at an optimal object distance provided by the second embodiment of the present invention;

[0053] Fig.10 This is a schematic diagram of an MTF curve of an industrial lens at an optimal object distance provided by Embodiment 2 of the present invention;

[0054] Fig.11 This is a schematic diagram of axial chromatic aberration of an industrial lens at an optimal object distance provided by the second embodiment of the present invention;

[0055] Fig.12 This is a schematic diagram of vertical axis chromatic aberration of an industrial lens at an optimal object distance provided by the second embodiment of the present invention;

[0056] Fig.13 This is a schematic diagram of the structure of an industrial lens at an optimal object distance provided by Embodiment 3 of the present invention;

[0057] Fig.14 Schematic diagram of Ray Fan of an industrial lens at an optimal object distance provided by Embodiment 3 of the present invention;

[0058] Fig.15 1 is a schematic diagram of a field curvature distortion curve of an industrial lens at an optimal object distance provided by Embodiment 3 of the present invention;

[0059] Fig.16 Schematic diagram of an MTF curve of an industrial lens at an optimal object distance provided by Embodiment 3 of the present invention;

[0060] Fig.17 This is a schematic diagram of axial chromatic aberration of an industrial lens at an optimal object distance provided by Embodiment 3 of the present invention;

[0061] Fig.18 This is a schematic diagram of vertical axis chromatic aberration of an industrial lens at an optimal object distance provided by Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0062] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0063] Embodiment 1

[0064] Figure 1 Schematic diagram of the structure of an industrial lens at an optimal object distance provided by the first embodiment of the present invention. Figure 1 As shown, the industrial lens provided by the embodiment of the present invention includes a first lens group S1, a second lens group S2 and a third lens group S3 which are arranged in sequence from the object plane to the image plane along the optical axis; the positions of the first lens group S1 and the third lens group S3 are fixed, and the position of the second lens group S2 can float along the optical axis; the first lens group S1 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 and an eighth lens 108; the second lens group S2 includes a ninth lens 109; the third lens group S3 includes a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a thirteenth lens 113, a fourteenth lens 114 and a fifteenth lens 115.

[0065] Specifically, the industrial lens provided by the embodiment of the present invention includes a first lens group S1, a third lens group S3, and a second lens group S2 located between the first lens group S1 and the third lens group S3 along the optical axis. Among them, the first lens group S1 and the third lens group S3 can be understood as lenses whose lens positions are fixed and unchanged, and the second lens group S2 can be understood as a lens group whose lens group position changes. The second lens group S2 specifically moves between the first lens group S1 and the third lens group S3. The focal length of the industrial lens is adjusted by the position change of the second lens group S2 to ensure that the industrial lens can achieve focus at different object distances and ensure clear imaging at different object distances. In addition, since the positions of the first lens group S1 and the third lens group S3 remain unchanged, under different working distances, the aberration change caused by the forward and backward movement of the second lens group S2 will be weakened by the movement of the second lens group S2 on the aberration because the first lens group S1 and the third lens group S3 are fixed and maintained symmetry, ensuring that the image quality of each working distance is balanced and the imaging quality is guaranteed.

[0066] Further, the first lens group S1 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 and an eighth lens 108; the second lens group S2 includes a ninth lens 109; the third lens group S3 includes a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a thirteenth lens 113, a fourteenth lens 114 and a fifteenth lens 115. That is, the first lens group S1 includes eight lenses, the second lens group S2 includes one lens, and the third lens group S3 includes six lenses. That is, the industrial lens includes fourteen lenses that remain fixed, and only one lens floats. In this way, only one lens floats to achieve floating focus. The number of lenses for floating focus is small, and the industrial lens has high stability, which ensures that the industrial lens can achieve high image quality imaging performance.

[0067] In summary, the industrial lens provided by the embodiment of the present invention is provided with a second lens group that can float along the optical axis, so as to ensure that focusing can be achieved at different working distances and clear imaging can be achieved at different working object distances; and the second lens group only includes the ninth lens, that is, only one lens is used for floating focusing, there are fewer lenses for floating focusing, and the lens has high stability. Furthermore, the first lens group and the third lens group are fixed, so that the influence of focusing on different object distances on the resolution can be reduced, and the image quality at each working distance is balanced, so as to achieve an industrial lens with high image quality imaging performance. In addition, the setting of fifteen lenses ensures that the number of lenses in the optical system is reasonably set, and the lens volume will not be larger due to too many lenses, nor will the aberration of a single lens due to the large optical focal length caused by too few lenses be larger. While miniaturizing the optical system, the imaging aberration is small and the imaging quality is high.

[0068] Based on the above embodiments, continue to refer to Figure 1 As shown, the industrial lens provided by the embodiment of the present invention also includes an aperture 116 and a filter 117. The aperture 116 can adjust the propagation direction of the light beam, which is beneficial to improving the imaging quality. In addition, in the industrial lens, the aperture 116 is arranged in the optical path between the eleventh lens 111 and the twelfth lens 112, that is, the aperture STO is arranged in the optical system, which is beneficial to reducing the aperture value and achieving a large aperture. The filter 117 is arranged in the optical path between the fifteenth lens 115 and the image plane, which can filter out stray light and improve the imaging effect.

[0069] Furthermore, the industrial lens provided in the embodiment of the present invention may also include a protective glass and an image acquisition element. The protective glass may be arranged on the image side of the filter, and the image acquisition element may be arranged on the image side of the protective glass. The protective glass is used to protect the optical system, and the image is acquired by the image acquisition element to realize the normal imaging function of the optical system.

[0070] On the basis of the above embodiments, the optical power of the first lens 101 is negative; the optical power of the second lens 102 is negative; the optical power of the third lens 103 is negative; the optical power of the fourth lens 104 is positive; the fifth lens 105 and the sixth lens 106 are cemented to form a first cemented lens, and the optical power of the first cemented lens is negative; the seventh lens 107 and the eighth lens 108 are cemented to form a second cemented lens, and the optical power of the second cemented lens is positive; the optical power of the ninth lens 109 is positive; the tenth lens 110 and the eleventh lens 111 are cemented to form a third cemented lens, and the optical power of the third cemented lens is positive; the twelfth lens 112, the thirteenth lens 113 and the fourteenth lens 114 are cemented to form a fourth cemented lens, and the optical power of the fourth cemented lens is negative; the optical power of the fifteenth lens 115 is positive.

[0071] Specifically, the focal length is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent.

[0072] In the industrial lens provided by the embodiment of the present invention, the first lens 101, the second lens 102 and the third lens 103 are the lenses that first adjust the incident light in the industrial lens. The setting of their negative focal length can ensure that the light has a larger diameter before entering the aperture, increasing the aperture of the industrial lens. The larger the aperture of the lens, the greater the amount of light entering, so that the lens can still clearly image in dim or dark conditions. In the embodiment of the present invention, the aperture number FNO of the industrial lens can be 1.9, which meets the large aperture setting of the industrial lens.

[0073] Furthermore, the setting of the positive optical power of the fourth lens 104 can realize timely correction of the large aberrations generated by the first lens 101, the second lens 102 and the third lens 103, especially can have a significant correction effect on the edge aberration of the industrial lens, thereby improving the imaging resolution of the optical system.

[0074] Furthermore, the fifth lens 105 and the sixth lens 106 have opposite optical powers and are glued together to form a first glued lens with negative optical power; the seventh lens 107 and the eighth lens 108 have opposite optical powers and are glued together to form a second glued lens with positive optical power; the tenth lens 110 and the eleventh lens 111 are glued together to form a third glued lens with positive optical power; the twelfth lens 112, the thirteenth lens 113 and the fourteenth lens 114 are glued together to form a fourth glued lens with negative optical power. Glued lenses can be used to minimize or eliminate chromatic aberration. Using glued lenses in industrial lenses can improve image quality and reduce reflection loss of light energy, thereby improving the clarity of lens imaging. In addition, the gluing of lenses omits the air space between the two lenses, making the optical system compact as a whole and meeting the requirements of system miniaturization. In addition, the gluing of lenses can reduce the tolerance sensitivity problems such as tilt / eccentricity generated by the lens unit during the assembly process. Exemplarily, the fifth lens 105 and the sixth lens 106 may be supported by a gasket or may be glued together by glue; the seventh lens 107 and the eighth lens 108 may be supported by a gasket or may be glued together by glue; the tenth lens 110 and the eleventh lens 111 may be supported by a gasket or may be glued together by glue; the twelfth lens 112, the thirteenth lens 113 and the fourteenth lens 114 may be supported by a gasket or may be glued together by glue. In addition, the first glued lens, the second glued lens, the ninth lens 109, the third glued lens, the fourth glued lens and the fifteenth lens 115 adopt a negative-positive-positive-positive-positive-negative-positive matching method, and the positive focal power and the negative focal power are matched, which is conducive to the correction of aberrations.

[0075] On the basis of the above embodiment, the optical power of the fifth lens 105 is Φ5, and the refractive index is ND5; the optical power of the sixth lens 106 is Φ6, and the refractive index is ND6; wherein, -1.7900≤Φ5 / Φ6≤-1.1300, 1.2700≤ND6 / ND5≤1.3600. The fifth lens 105 and the sixth lens 106 are two lenses matched with positive and negative lenses, and the refractive index of the materials of the two lenses is greatly different. When the above conditions are met, the spherical aberration can be effectively corrected to improve the imaging quality during detection.

[0076] On the basis of the above embodiment, the Abbe number of the seventh lens 107 is VD7, the Abbe number of the eighth lens 108 is VD8, the Abbe number of the thirteenth lens 113 is VD13, and the Abbe number of the fourteenth lens 114 is VD14; wherein, 1.9100≤|VD7 / VD8|≤2.9500, 4.6800≤VD13 / VD14≤5.3000. The seventh lens 107 and the eighth lens 108 are glued together, and the thirteenth lens 113 and the fourteenth lens 114 are also glued together. When the Abbe numbers of the lenses in the glued lens group differ greatly, the system chromatic aberration can be effectively corrected, the imaging quality can be improved, and the detection effect of the industrial lens can be clearer and more accurate.

[0077] Based on the above embodiment, the total optical length of the industrial lens is TTL, the focal length is EFL, the maximum effective aperture is DM, the image plane size is IM, the working F number is FNO, and the field of view is FOV; wherein, 17.5200≤TTL / EFL≤17.6500, 2.0400≤TTL / DM≤2.0600,

[0078] 3.0500≤IM / FNO≤3.0700, FOV≥96.3700°.

[0079] Specifically, TTL is the distance from the front end of the first lens 101 to the image plane, and DM is the maximum effective aperture of the lens. While ensuring that the image height remains unchanged, the shorter the total length, the smaller the maximum effective aperture, and the smaller the corresponding volume. Therefore, setting 2.0400≤TTL / DM≤2.0600 can reduce the volume while achieving a large image height. Further, EFL represents the overall focal length of the lens, and FOV represents the field of view of the lens. Line scanning industrial lenses with large target surfaces are usually large in size and require many lenses for aberration correction. Therefore, setting 17.5200≤TTL / EFL≤17.6500 and FOV≥96.3700° can ensure good aberration correction effect and good imaging quality under a larger field of view. Further, IM represents the image plane size of the lens, and FNO represents the working aperture number of the lens. For the same image plane, the smaller the working aperture number, the larger the aperture of the lens, and the greater the amount of light entering, so that the brightness and clarity of the obtained picture are higher. Therefore, setting 3.0500≤IM / FNO≤3.0700 to meet this range can ensure good brightness and clarity of the imaging picture. The present invention uses only 15 lenses to achieve high-quality imaging pictures on a super-large target surface, while controlling the total length within 90.01 mm, minimizing the cost and volume, and ensuring clear resolution quality.

[0080] Based on the above embodiment, the refractive index Nd1 of the first lens 101 satisfies Nd1 ≥ 1.9300. As the front-end lens of the industrial lens, the first lens 101 has a higher refractive index, which is helpful for the design of short-focus lenses, so that incident light at large angles tends to be flatter more quickly, and while ensuring the maximum range of information collection of the object to be tested, the number of lenses is reduced to meet the design requirements of lightweight industrial lenses.

[0081] Based on the above embodiments, continue to refer to Figure 1 As shown, the industrial lens also includes an aperture 116, which is arranged in the optical path between the eleventh lens 111 and the twelfth lens 112; the optical focal length of the lens group formed by the ninth lens 109, the tenth lens 110 and the eleventh lens 111 is ΦZ1, and the optical focal length of the lens group formed by the twelfth lens 112, the thirteenth lens 113 and the fourteenth lens 114 is ΦZ2; the maximum optical distortion of the industrial lens is DISG.MAX; wherein, -0.9600≤ΦZ1 / ΦZ2≤-0.7500; 0≤|DISG.MAX|≤0.500%.

[0082] Specifically, the aperture 116 can be set to adjust the propagation direction of the light beam, which is beneficial to improving the imaging quality. In addition, in the scanning lens, the aperture 116 is set in the optical path between the eleventh lens 111 and the twelfth lens 112, that is, the aperture STO is set in the optical system, which is beneficial to reducing the aperture value and achieving a large aperture. Further, the ninth lens 109 to the fourteenth lens 114 form a symmetrical structure with the aperture 116 as the center, the front and rear lens groups have opposite focal lengths, and the absolute values ​​are close, that is, -0.9600≤ΦZ1 / ΦZ2≤-0.7500, which can effectively correct the optical distortion of the system, reduce the impact of imaging distortion, and always control the maximum value of the optical distortion of the system within the range of ±0.5%, reduce the field curvature of the system, better reflect the actual value of the measured object, and make the data obtained from industrial detection more accurate.

[0083] Based on the above embodiment, the shape factor of the fourth lens 104 is ξ4, and the minimum value of the full-field relative illumination of the industrial lens is RI.MIN; wherein, 6.0400≤|ξ4|≤12.1400; 84.2000%≤RI.MIN.

[0084] Specifically, the shape factor is a parameter that affects the basic optical performance of the lens. The shape factor can be adjusted by changing the curvature, aperture, material, etc. of the lens. The fourth lens 104 is made of a high refractive index material and has a positive focal length. It is located at a position where light converges and has a large shape factor, which can optimize the focusing ability and imaging quality of the system. When the lens at this position meets the above conditions, it can more effectively correct aberrations and improve imaging quality and relative illumination.

[0085] On the basis of the above embodiment, the first lens 101 includes a first object-side surface close to the object plane and a first image-side surface close to the image plane, the first object-side surface is convex, and the first image-side surface is concave; the second lens 102 includes a second object-side surface close to the object plane and a second image-side surface close to the image plane, the second object-side surface is convex, and the second image-side surface is concave; the third lens 103 includes a third object-side surface close to the object plane and a third image-side surface close to the image plane, the third object-side surface is concave, and the third image-side surface is concave; the fourth lens 104 includes a fourth object-side surface close to the object plane and a fourth image-side surface close to the image plane, the fourth object-side surface is concave, The fourth image side surface is convex; the fifth lens 105 includes a fifth object side surface close to the object plane and a fifth image side surface close to the image plane, the fifth object side surface is concave, and the fifth image side surface is convex; the sixth lens 106 includes a sixth object side surface close to the object plane and a sixth image side surface close to the image plane, the sixth object side surface is concave, and the sixth image side surface is convex; the seventh lens 107 includes a seventh object side surface close to the object plane and a seventh image side surface close to the image plane, the seventh object side surface is concave or convex, and the seventh image side surface is concave or convex; the eighth lens 108 includes an eighth object side surface close to the object plane and an eighth image side surface close to the image plane, the eighth object side surface is concave or convex. The eighth object side surface is convex or concave, and the eighth image side surface is convex; the ninth lens 109 includes a ninth object side surface close to the object plane and a ninth image side surface close to the image plane, the ninth object side surface is convex, and the ninth image side surface is concave or convex; the tenth lens 110 includes a tenth object side surface close to the object plane and a tenth image side surface close to the image plane, the tenth object side surface is convex, and the tenth image side surface is concave; the eleventh lens 111 includes an eleventh object side surface close to the object plane and an eleventh image side surface close to the image plane, the eleventh object side surface is convex, and the eleventh image side surface is concave or convex; the twelfth lens 112 includes a twelfth object side surface close to the object plane The twelfth object side surface is convex, and the twelfth image side surface is concave; the thirteenth lens 113 includes a thirteenth object side surface close to the object plane and a thirteenth image side surface close to the image plane, the thirteenth object side surface is convex, and the thirteenth image side surface is convex; the fourteenth lens 114 includes a fourteenth object side surface close to the object plane and a fourteenth image side surface close to the image plane, the fourteenth object side surface is concave, and the fourteenth image side surface is concave or convex; the fifteenth lens 115 includes a fifteenth object side surface close to the object plane and a fifteenth image side surface close to the image plane, the fifteenth object side surface is convex, and the fifteenth image side surface is convex.

[0086] Specifically, the object side of the lens can be understood as the surface of the lens close to the object plane, and the image side of the lens can be understood as the surface of the lens close to the image plane. The object side of the first lens 101 is convex, and the image side is concave. The object side of the second lens 102 is convex, and the image side is concave. It can be understood that the object side of the first lens 101 and the second lens 102 are both convex toward the object plane at the near optical axis position, and the image side is both concave toward the image plane at the near optical axis position, that is, the first lens 101 and the second lens 102 are both lenses of convex-concave structure. In addition, the first lens 101 and the second lens 102 can be meniscus negative lenses. The surface shape of the first lens 101 is combined with the optical power parameters of the first lens 101, and the surface shape of the second lens 102 is combined with the optical power parameters of the second lens 102, which can gather as much light of a large field of view as possible into the system, which is conducive to improving the field of view angle of the optical system. The object side surface of the third lens 103 is a concave surface, and the image side surface is a concave surface, which can be understood as the object side surface of the third lens 103 is concave toward the object plane at the near optical axis position, and the image side surface is concave toward the image plane at the near optical axis position, that is, the third lens 103 is a lens with a double concave structure. The object side surfaces of the fourth lens 104, the fifth lens 105, and the sixth lens 106 are all concave surfaces, and the image side surfaces are all convex surfaces, which can be understood as the object side surfaces of the fourth lens 104, the fifth lens 105, and the sixth lens 106 are all concave toward the object plane at the near optical axis position, and the image side surfaces are all convex toward the image plane at the near optical axis position, that is, the fourth lens 104, the fifth lens 105, and the sixth lens 106 are all lenses with concave-convex structures. The object side surface of the seventh lens 107 is a concave or convex surface, and the image side surface is a concave or convex surface. It can be understood that the object side surface of the seventh lens 107 is concave or convex toward the object plane at the near optical axis position, and the image side surface is concave or convex toward the image plane at the near optical axis position, that is, the seventh lens 107 can be a lens with a double convex structure, a lens with a concave-convex structure, or a lens with a convex-concave structure. Embodiment 1 is described by taking the seventh lens 107 as a lens with a double convex structure as an example. The object side surface of the eighth lens 108 is a concave or convex surface, and the image side surface is a convex surface. It can be understood that the object side surface of the eighth lens 108 is concave or convex toward the object plane at the near optical axis position, and the image side surface is convex toward the image plane at the near optical axis position, that is, the eighth lens 108 can be a lens with a concave-convex or double convex structure. Embodiment 1 is described by taking the eighth lens 108 as a lens with a concave-convex structure as an example. The object side surface of the ninth lens 109 is a convex surface, and the image side surface is a concave surface or a convex surface. It can be understood that the object side surface of the ninth lens 109 is convex toward the object plane at the near optical axis position, and the image side surface is concave or convex toward the image plane at the near optical axis position, that is, the ninth lens 109 can be a lens with a convex-concave or biconvex structure. Embodiment 1 is described by taking the ninth lens 109 as a lens with a biconvex structure as an example.The object side surface of the tenth lens 110 is convex, and the image side surface of the tenth lens is concave. It can be understood that the object side surface of the tenth lens is convex toward the object plane at the near optical axis position, and the image side surface is concave toward the image plane at the near optical axis position, that is, the tenth lens 110 is a lens with a convex-concave structure. The object side surface of the eleventh lens 111 is convex, and the image side surface is concave or convex. It can be understood that the object side surface of the eleventh lens is convex toward the object plane at the near optical axis position, and the image side surface is concave or convex toward the image plane at the near optical axis position, that is, the eleventh lens 111 can be a lens with a convex-concave or biconvex structure. Embodiment 1 is described by taking the eleventh lens as a lens with a convex-concave structure as an example. The object side surface of the twelfth lens 112 is convex, and the image side surface is concave. It can be understood that the object side surface of the twelfth lens is convex toward the object plane at the near optical axis position, and the image side surface is concave toward the image plane at the near optical axis position, that is, the twelfth lens 112 is a lens with a convex-concave structure. The object side surface of the thirteenth lens 113 is convex, and the three image side surfaces are convex. It can be understood that the object side surface of the thirteenth lens is convex toward the object plane at the near optical axis position, and the image side surfaces are all convex toward the image plane at the near optical axis position, that is, the thirteenth lens 113 is a lens with a double convex structure. The object side surface of the fourteenth lens 114 is a concave surface, and the image side surface is a concave surface or a convex surface. It can be understood that the object side surface of the fourteenth lens is concave toward the object plane at the near optical axis position, and the image side surface is concave or convex toward the image plane at the near optical axis position, that is, the fourteenth lens 114 is a lens with a double concave or concave-convex structure. Embodiment 1 is described by taking the fourteenth lens as a lens with a double concave structure as an example. The object side surface of the fifteenth lens 115 is a convex surface, and the image side surface is a convex surface. It can be understood that the object side surface of the fifteenth lens is convex toward the object plane at the near optical axis position, and the image side surface is convex toward the image plane at the near optical axis position, that is, the fifteenth lens 112 is a lens with a double convex structure. By properly setting the concave and convex surface types of each lens, for a glued lens, at least two adjacent lenses can be glued together. On the other hand, the distance between adjacent lenses can be reduced, which is conducive to realizing a small-volume industrial lens design.

[0087] Based on the above embodiments, the first lens 101, the third lens 103, the fourth lens 104, the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the ninth lens 109, the tenth lens 110, the eleventh lens 111, the twelfth lens 112, the thirteenth lens 113, and the fourteenth lens 114 are all glass spherical lenses; the second lens 102 and the fifteenth lens 115 are all glass aspherical lenses.

[0088] Specifically, by setting the second lens 102 and the fifteenth lens 115 to be aspherical lenses, off-axis aberrations can be corrected, including field curvature, coma, astigmatism, etc. The first lens 101, the third lens 103, the fourth lens 104, the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the ninth lens 109, the tenth lens 110, the eleventh lens 111, the twelfth lens 112, the thirteenth lens 113 and the fourteenth lens 14 are all glass spherical lenses. The optical structure of 13 glass spherical lenses and 2 glass aspherical lenses is used to better correct chromatic aberration and aberration, improve image quality, and reduce processing costs to achieve higher cost performance. The materials of the glass spherical lens and the glass aspherical lens are various types of glass known to those skilled in the art, and the embodiments of the present invention will not be repeated or limited to this.

[0089] As a feasible implementation method, the parameters of each lens in the industrial lens are described below.

[0090] Table 1 Optical design values ​​of industrial lens in Example 1

[0091] Scope of protection Example 1 Lower limit Upper limit TTL / EFL 17.6451 17.5200 17.6500 TTL / DM 2.0454 2.0400 2.0600 IM / FNO 3.0617 3.0500 3.0700 EFL 5.1006 5.1000 5.1400 TTL 90.0000 89.9900 90.0100 FOV 96.8057 96.3700 96.8100 ND1 1.9722 1.9300 2.0800 |VD7 / VD8| 2.9412 1.9100 2.9500 VD13 / VD14 5.2947 4.6800 5.3000 ND6 / ND5 1.2906 1.2700 1.3600 Φ5 / Φ6 -1.1534 -1.7900 -1.1300 ΦZ1 / ΦZ2 -0.9523 -0.9600 -0.7500 |DISG.MAX| 0.4927％ 0.4900％ 0.5000％ |ξ4| 6.1367 6.0400 12.1400 RI.MIN 84.2088％ 84.2000％ 86.1000％ Φ1 -0.0156 -0.0220 -0.0150 Φ2 -0.0438 -0.0440 -0.0400 Φ3 -0.0457 -0.0540 -0.0300 Φ4 0.0108 0.0090 0.0180 Φ5-6 -0.0013 -0.0110 -0.0010 Φ7-8 0.0114 0.0110 0.0230 Φ9 0.0293 0.0160 0.0300 Φ10-11 0.0097 0.0090 0.0270 Φ12-14 -0.0402 -0.0530 -0.0400 Φ15 0.1060 0.1010 0.1070

[0092] Table 2 Design values ​​of optical physical parameters of industrial lenses

[0093]

[0094]

[0095] The surface numbers in Table 2 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface, "2" represents the object side surface of the first lens, "3" represents the image side surface of the first lens, and so on. The radius of curvature represents the degree of curvature of the corresponding lens surface. A positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side. "Infinity" represents that the surface is a plane and the radius of curvature is infinite. The thickness represents the central axial distance from the current surface to the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. The space represents that the current position is air and the refractive index is 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to the light. The semi-aperture represents half of the aperture size of the current surface. When the interval of the 15th surface is 0.138mm and the interval of the 18th surface is -0.138mm, the focus can be focused to an infinite object distance. When the interval of the 15th surface is 4.793mm and the interval of the 18th surface is -4.793mm, the focus can be focused to an object distance of 50mm.

[0096] Table 3 Design value of aspheric coefficient of industrial lens

[0097]

[0098] The K value in Table 2 represents the numerical value of the cone coefficient of the aspheric surface.

[0099] 1.406197E-04 means 1.406197*10 -4 , the remaining parameters can be expressed in this way.

[0100] Furthermore, the aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0101]

[0102] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the cone coefficient; AE is the coefficient of the 4th, 6th, 8th, 10th, and 12th order terms of the aspheric polynomial.

[0103] Figure 2 This is a Ray Fan diagram of an industrial lens at an optimal object distance provided by Example 1 of the present invention. The ray fan diagram is one of the most commonly used evaluation methods in modern optical design. The horizontal axis is the beam aperture, and the vertical axis is the vertical axis aberration. The most ideal curve is a straight line that coincides with the horizontal axis, indicating that all light rays converge at the same point on the image plane, and the corresponding interval on the vertical axis of the curve is the maximum dispersion range of the light beam on the ideal image plane. The ray fan diagram can not only reflect the monochromatic aberrations of different wavelengths, but also indicate the size of the vertical axis chromatic aberration. By Figure 2 It can be seen that each wavelength of the system in each field of view is well close to the horizontal axis, indicating that the vertical axis aberration of each wavelength of the system 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, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0104] Figure 3 1 is a schematic diagram of a field curvature distortion curve of an industrial lens at an optimal object distance provided by the first embodiment of the present invention. In the left coordinate system of the figure, the horizontal coordinate represents the magnitude of the field curvature, in units of mm; the vertical coordinate represents the normalized image height, in units of mm; wherein T represents the meridian, S represents the sagittal; Figure 3 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at 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 size of the distortion, in units of %; the vertical coordinate represents the normalized image height, without units. Figure 3 It can be seen that the distortion of the lens provided in this embodiment is well corrected, and the optical distortion is less than ±0.5%.

[0105] Figure 4This is a schematic diagram of the MTF curve of an industrial lens at an optimal object distance provided by the first embodiment of the present invention. The horizontal axis is the spatial frequency, which refers to the number of black and white line pairs / 1mm, and the vertical axis is the modulation modulus (M' / M). M refers to the grating modulation degree before imaging, and M' refers to the grating modulation degree after imaging, so 0≤M' / M≤1. The MTF curve shows the resolution of the optical system for objects at different frequencies in different fields of view, meridian and sagittal directions, and reflects the degree of imaging of the image quality of the object after passing through the optical system. The higher the MTF, the higher the imaging quality of the lens. Figure 4 It can be seen that the image quality of the lens of the present invention at 200 pl / mm from the center field of view to the edge field of view is higher than 0.3 MTF, and the imaging has excellent resolution.

[0106] Figure 5 This is a schematic diagram of the axial chromatic aberration of an industrial lens at the optimal object distance provided by the first embodiment of the present invention. In the figure, the vertical direction represents the normalization of the pupil plane of the 0 field of view, 0 represents the center of the pupil, and the vertical vertex represents the vertex of the pupil; the horizontal direction is the axial chromatic aberration of different wavelengths (specifically 460nm, 530nm and 620nm), in millimeters (mm). As can be seen in the figure, the axial chromatic aberration of the full pupil of the lens of the present invention is less than 19μm, and the imaging has excellent clarity.

[0107] Figure 6 This is a schematic diagram of vertical axis chromatic aberration of an industrial lens at an optimal object distance provided by the first embodiment of the present invention. In the figure, the vertical direction represents the field of view angle, 0 represents the field of view angle parallel to the optical axis, and the vertical vertex represents the maximum half field of view angle. As can be seen from the figure, at each wavelength of the system (specifically 460nm, 530nm and 620nm), the vertical axis chromatic aberration from the center field of view to the edge field of view of the lens is less than 1.1μm, resulting in higher imaging quality.

[0108] In summary, the industrial lens provided by the embodiment of the present invention adopts an all-glass 15G structure, and achieves focusing from 50mm to infinity by matching lens materials and reasonably allocating the focal length of each component, and adopts an intermediate group focusing method. At the optimal object distance, the industrial lens design with low distortion and large target surface and high resolution can be taken into account. The system focal length is 5mm, the maximum aperture is F1.9, the optimal object distance is 150mm, |maximum optical distortion| <0.5%, and the imaging quality can reach 200pl / mm>0.3MTF.

[0109] Embodiment 2

[0110] Figure 7 Schematic diagram of the structure of an industrial lens at an optimal object distance provided by the second embodiment of the present invention. Figure 7As shown, the industrial lens provided by the second embodiment of the present invention includes a first lens group S1, a second lens group S2 and a third lens group S3, whose optical axes are arranged in sequence from the object plane to the image plane; the positions of the first lens group S1 and the third lens group S3 are fixed, and the position of the second lens group S2 can float along the optical axis; the first lens group S1 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 and an eighth lens 108; the second lens group S2 includes a ninth lens 109; the third lens group S3 includes a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a thirteenth lens 113, a fourteenth lens 114 and a fifteenth lens 115

[0111] The difference between the second embodiment and the first embodiment is that the object side surface of the seventh lens is a concave surface, the image side surface of the eleventh lens is a convex surface, and the image side surface of the fourteenth lens is a convex surface.

[0112] Other parameters are the same as those in the first embodiment and will not be described again here.

[0113] As another feasible implementation, specific parameters in the industrial lens are described below.

[0114] Table 4 Optical design values ​​of the fixed focus lens in Example 2

[0115] Scope of protection Example 2 Lower limit Upper limit TTL / EFL 17.6022 17.5200 17.6500 TTL / DM 2.0515 2.0400 2.0600 IM / FNO 3.0581 3.0500 3.0700 EFL 5.1127 5.1000 5.1400 TTL 89.9950 89.9900 90.0100 FOV 96.6232 96.3700 96.8100 ND1 1.9393 1.9300 2.0800 |VD7 / VD8| 1.9596 1.9100 2.9500 VD13 / VD14 5.2943 4.6800 5.3000 ND6 / ND5 1.3571 1.2700 1.3600 Φ5 / Φ6 -1.3107 -1.7900 -1.1300 ΦZ1 / ΦZ2 -0.8269 -0.9600 -0.7500 |DISG.MAX| 0.4947％ 0.4900％ 0.5000％ |ξ4| 12.1330 6.0400 12.1400 RI.MIN 84.5525％ 84.2000％ 86.1000％ Φ1 -0.0213 -0.0220 -0.0150 Φ2 -0.0403 -0.0440 -0.0400 Φ3 -0.0304 -0.0540 -0.0300 Φ4 0.0100 0.0090 0.0180 Φ5-6 -0.0052 -0.0110 -0.0010 Φ7-8 0.0116 0.0110 0.0230 Φ9 0.0242 0.0160 0.0300 Φ10-11 0.0216 0.0090 0.0270 Φ12-14 -0.0522 -0.0530 -0.0400 Φ15 0.1018 0.1010 0.1070

[0116] Table 5 Design values ​​of optical physical parameters of industrial lenses

[0117]

[0118]

[0119] The surface numbers in Table 5 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface, "2" represents the object side surface of the first lens, "3" represents the image side surface of the first lens, and so on. The radius of curvature represents the degree of curvature of the corresponding lens surface. A positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side. "Infinity" represents that the surface is a plane and the radius of curvature is infinite. The thickness represents the central axial distance from the current surface to the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. The space represents that the current position is air and the refractive index is 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to the light. The semi-aperture represents half of the aperture size of the current surface. When the interval of the 15th surface is 0.148mm and the interval of the 18th surface is -0.148mm, the focus can be focused to an infinite object distance. When the interval of the 15th surface is 5.617mm and the interval of the 18th surface is -5.617mm, the focus can be focused to an object distance of 50mm.

[0120] Table 6 Design value of aspheric coefficient of industrial lens

[0121]

[0122] The K value in Table 6 represents the numerical value of the cone coefficient of the aspheric surface.

[0123] 1.543630E-04 means 1.543630*10 -4 , the remaining parameters can be expressed in this way.

[0124] Furthermore, the aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0125]

[0126] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the cone coefficient; AE is the coefficient of the 4th, 6th, 8th, 10th, and 12th order terms of the aspheric polynomial.

[0127] Figure 8 This is a Ray Fan diagram of an industrial lens at an optimal object distance provided by Example 2 of the present invention. The ray fan diagram is one of the most commonly used evaluation methods in modern optical design. The horizontal axis is the beam aperture, and the vertical axis is the vertical axis aberration. The most ideal curve is a straight line that coincides with the horizontal axis, indicating that all light rays converge at the same point on the image plane, and the corresponding interval on the vertical axis of the curve is the maximum dispersion range of the light beam on the ideal image plane. The ray fan diagram can not only reflect the monochromatic aberrations of different wavelengths, but also indicate the size of the vertical axis chromatic aberration. By Figure 8 It can be seen that each wavelength of the system in each field of view is well close to the horizontal axis, indicating that the vertical axis aberration of each wavelength of the system 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, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0128] Fig. 9 : is a schematic diagram of a field curvature distortion curve of an industrial lens at an optimal object distance provided by the second embodiment of the present invention. In the left coordinate system of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; wherein T represents the meridian, and S represents the sagittal; Fig. 9 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at 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 size of the distortion, in units of %; the vertical coordinate represents the normalized image height, without units. Fig. 9It can be seen that the distortion of the lens provided in this embodiment is well corrected, and the optical distortion is less than ±0.5%.

[0129] Fig.10 This is a schematic diagram of the MTF curve of an industrial lens at the optimal object distance provided by the second embodiment of the present invention. The horizontal axis is the spatial frequency, which refers to the number of black and white line pairs / 1mm, and the vertical axis is the modulation modulus (M' / M). M refers to the grating modulation degree before imaging, and M' refers to the grating modulation degree after imaging, so 0≤M' / M≤1. The MTF curve shows the resolution of the optical system for objects at different frequencies in different fields of view, meridian and sagittal directions, and reflects the imaging degree of the image quality of the object after passing through the optical system. The higher the MTF, the higher the imaging quality of the lens. Fig.10 It can be seen that the image quality of the lens of the present invention at 200 pl / mm from the center field of view to the edge field of view is higher than 0.38 MTF, and the imaging has excellent resolution.

[0130] Fig.11 This is a schematic diagram of the axial chromatic aberration of an industrial lens at the optimal object distance provided by the second embodiment of the present invention. In the figure, the vertical direction represents the normalization of the pupil plane of the 0 field of view, 0 represents the center of the pupil, and the vertical vertex represents the vertex of the pupil; the horizontal direction is the axial chromatic aberration of different wavelengths (specifically 460nm, 530nm and 620nm), in millimeters (mm). As can be seen in the figure, the axial chromatic aberration of the full pupil of the lens of the present invention is less than 9μm, and the imaging has excellent clarity.

[0131] Fig.12 This is a schematic diagram of vertical axis chromatic aberration of an industrial lens at an optimal object distance provided by Example 2 of the present invention. In the figure, the vertical direction represents the field of view angle, 0 represents the field of view angle parallel to the optical axis, and the vertical vertex represents the maximum half field of view angle. As can be seen from the figure, at each wavelength of the system (specifically 460nm, 530nm and 620nm), the vertical axis chromatic aberration from the center field of view to the edge field of view of the lens is less than 0.9μm, resulting in higher imaging quality.

[0132] In summary, the industrial lens provided by the embodiment of the present invention adopts an all-glass 15G structure, and achieves focusing from 50mm to infinity by matching lens materials and reasonably allocating the focal length of each component, and adopts an intermediate group focusing method. At the optimal object distance, the industrial lens design with low distortion and large target surface and high resolution can be taken into account. The system focal length is 5mm, the maximum aperture is F1.9, the optimal object distance is 150mm, |maximum optical distortion| <0.5%, and the imaging quality can reach 200pl / mm>0.38MTF.

[0133] Embodiment 3

[0134] Fig.13Schematic diagram of the structure of an industrial lens at an optimal object distance provided by the third embodiment of the present invention. Fig.13 As shown, the industrial lens provided by Embodiment 3 of the present invention comprises a first lens group S1, a second lens group S2 and a third lens group S3, whose optical axes are arranged in sequence from the object plane to the image plane; the positions of the first lens group S1 and the third lens group S3 are fixed, and the position of the second lens group S2 can float along the optical axis; the first lens group S1 comprises 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 and an eighth lens 108; the second lens group S2 comprises a ninth lens 109; and the third lens group S3 comprises a tenth lens 110, an eleventh lens 111, a twelfth lens 112, a thirteenth lens 113, a fourteenth lens 114 and a fifteenth lens 115.

[0135] The difference between the third embodiment and the first embodiment is that the image side surface of the seventh lens is a concave surface, the object side surface of the eighth lens is a convex surface, the image side surface of the ninth lens is a concave surface, and the image side surface of the eleventh lens is a convex surface.

[0136] Other parameters are the same as those in the first embodiment and will not be described again here.

[0137] As another feasible implementation, specific parameters in the industrial lens are described below.

[0138] Table 7 Optical design values ​​of the fixed focus lens in Example 3

[0139] Scope of protection Example 3 Lower limit Upper limit TTL / EFL 17.5290 17.5200 17.6500 TTL / DM 2.0427 2.0400 2.0600 IM / FNO 3.0673 3.0500 3.0700 EFL 5.1343 5.1000 5.1400 TTL 89.9990 89.9900 90.0100 FOV 96.3739 96.3700 96.8100 ND1 2.0734 1.9300 2.0800 |VD7 / VD8| 1.9190 1.9100 2.9500 VD13 / VD14 4.6815 4.6800 5.3000 ND6 / ND5 1.2722 1.2700 1.3600 Φ5 / Φ6 -1.7859 -1.7900 -1.1300 ΦZ1 / ΦZ2 -0.7583 -0.9600 -0.7500 |DISG.MAX| 0.4926％ 0.4900％ 0.5000％ |ξ4| 6.0441 6.0400 12.1400 RI.MIN 86.0924％ 84.2000％ 86.1000％ Φ1 -0.0175 -0.0220 -0.0150 Φ2 -0.0405 -0.0440 -0.0400 Φ3 -0.0530 -0.0540 -0.0300 Φ4 0.0174 0.0090 0.0180 Φ5-6 -0.0101 -0.0110 -0.0010 Φ7-8 0.0221 0.0110 0.0230 Φ9 0.0164 0.0160 0.0300 Φ10-11 0.0266 0.0090 0.0270 Φ12-14 -0.0521 -0.0530 -0.0400 Φ15 0.1046 0.1010 0.1070

[0140] Table 8 Optical design values ​​of each lens in industrial lens

[0141]

[0142]

[0143] The surface numbers in Table 8 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface, "2" represents the object side surface of the first lens, "3" represents the image side surface of the first lens, and so on. The radius of curvature represents the degree of curvature of the corresponding lens surface. A positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side. "Infinity" represents that the surface is a plane and the radius of curvature is infinite. The thickness represents the central axial distance from the current surface to the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. The space represents that the current position is air and the refractive index is 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to the light. The semi-aperture represents half of the aperture size of the current surface. When the interval of the 15th surface is 0.131mm and the interval of the 18th surface is -0.131mm, the focus can be adjusted to an infinite object distance. When the interval of the 15th surface is 5.986mm and the interval of the 18th surface is -5.986mm, the focus can be adjusted to an object distance of 50mm.

[0144] Table 9 Design value of aspheric coefficient of industrial lens

[0145]

[0146] The K value in Table 9 represents the numerical value of the cone coefficient of the aspheric surface.

[0147] 1.565131E-04 means 1.565131*10 - 4. The remaining parameters can be expressed in this way.

[0148] Furthermore, the aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0149]

[0150] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the cone coefficient; AE is the coefficient of the 4th, 6th, 8th, 10th, and 12th order terms of the aspheric polynomial.

[0151] Fig.14 This is a Ray Fan diagram of an industrial lens at an optimal object distance provided by Example 3 of the present invention. The ray fan diagram is one of the most commonly used evaluation methods in modern optical design. The horizontal axis is the beam aperture, and the vertical axis is the vertical axis aberration. The most ideal curve is a straight line that coincides with the horizontal axis, indicating that all light rays converge at the same point on the image plane, and the corresponding interval on the vertical axis of the curve is the maximum dispersion range of the light beam on the ideal image plane. The ray fan diagram can not only reflect the monochromatic aberrations of different wavelengths, but also indicate the size of the vertical axis chromatic aberration. By Fig.14It can be seen that each wavelength of the system in each field of view is well close to the horizontal axis, indicating that the vertical axis aberration of each wavelength of the system 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, thereby ensuring that the optical system can achieve high-resolution imaging requirements.

[0152] Fig.15 1 is a schematic diagram of a field curvature distortion curve of an industrial lens at an optimal object distance provided by the third embodiment of the present invention. In the left coordinate system of the figure, the horizontal coordinate represents the magnitude of the field curvature, in units of mm; the vertical coordinate represents the normalized image height, in units of mm; wherein T represents the meridian, S represents the sagittal; Fig.15 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at 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 size of the distortion, in units of %; the vertical coordinate represents the normalized image height, without units. Fig.15 It can be seen that the distortion of the lens provided in this embodiment is well corrected, and the optical distortion is less than ±0.5%.

[0153] Fig.16 This is a schematic diagram of the MTF curve of an industrial lens at the optimal object distance provided by the third embodiment of the present invention. The horizontal axis is the spatial frequency, which refers to the number of black and white line pairs / 1mm, and the vertical axis is the modulation modulus (M' / M). M refers to the grating modulation degree before imaging, and M' refers to the grating modulation degree after imaging, so 0≤M' / M≤1. The MTF curve shows the resolution of the optical system for objects at different frequencies in different fields of view, meridian and sagittal directions, and reflects the imaging degree of the image quality of the object after passing through the optical system. The higher the MTF, the higher the imaging quality of the lens. Fig.16 It can be seen that the image quality of the lens of the present invention at 200 pl / mm from the center field of view to the edge field of view is higher than 0.34 MTF, and the imaging has excellent resolution.

[0154] Fig.17 This is a schematic diagram of the axial chromatic aberration of an industrial lens at the optimal object distance provided by the third embodiment of the present invention. In the figure, the vertical direction represents the normalization of the pupil plane of the 0 field of view, 0 represents the center of the pupil, and the vertical vertex represents the vertex of the pupil; the horizontal direction is the axial chromatic aberration of different wavelengths (specifically 460nm, 530nm and 620nm), in millimeters (mm). As can be seen in the figure, the axial chromatic aberration of the full pupil of the lens of the present invention is less than 9μm, and the imaging has excellent clarity.

[0155] Fig.18This is a schematic diagram of vertical axis chromatic aberration of an industrial lens at an optimal object distance provided by Example 3 of the present invention. In the figure, the vertical direction represents the field of view angle, 0 represents the field of view angle parallel to the optical axis, and the vertical vertex represents the maximum half field of view angle. As can be seen from the figure, at each wavelength of the system (specifically 460nm, 530nm and 620nm), the vertical axis chromatic aberration from the center field of view to the edge field of view of the lens is less than 0.8μm, resulting in higher imaging quality.

[0156] In summary, the industrial lens provided by the embodiment of the present invention adopts an all-glass 15G structure, and achieves focusing from 50mm to infinity by matching lens materials and reasonably allocating the focal length of each component, and adopts an intermediate group focusing method. At the optimal object distance, the industrial lens design with low distortion and large target surface and high resolution can be taken into account. The system focal length is 5mm, the maximum aperture is F1.9, the optimal object distance is 150mm, |maximum optical distortion| <0.5%, and the imaging quality can reach 200pl / mm>0.34MTF.

[0157] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An industrial lens, characterized in that: It comprises a first lens group, a second lens group and a third lens group which are arranged in sequence from the object plane to the image plane along the optical axis; the positions of the first lens group and the third lens group are fixed, and the position of the second lens group can float along the optical axis; The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens; the second lens group includes a ninth lens; and the third lens group includes a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens.

2. The industrial lens according to claim 1, characterized in that: The optical focal power of the first lens is negative; the optical focal power of the second lens is negative; the optical focal power of the third lens is negative; the optical focal power of the fourth lens is positive; the fifth lens and the sixth lens are cemented to form a first cemented lens, and the optical focal power of the first cemented lens is negative; the seventh lens and the eighth lens are cemented to form a second cemented lens, and the optical focal power of the second cemented lens is positive; the optical focal power of the ninth lens is positive; the tenth lens and the eleventh lens are cemented to form a third cemented lens, and the optical focal power of the third cemented lens is positive; the twelfth lens, the thirteenth lens and the fourteenth lens are cemented to form a fourth cemented lens, and the optical focal power of the fourth cemented lens is negative; the optical focal power of the fifteenth lens is positive.

3. The industrial lens according to claim 2, characterized in that: The optical power of the fifth lens is Φ5, and the refractive index is ND5; the optical power of the sixth lens is Φ6, and the refractive index is ND6; Among them, -1.7900≤Φ5 / Φ6≤-1.1300, 1.2700≤ND6 / ND5≤1.3600.

4. The industrial lens according to claim 2, characterized in that: The Abbe number of the seventh lens is VD7, the Abbe number of the eighth lens is VD8, the Abbe number of the thirteenth lens is VD13, and the Abbe number of the fourteenth lens is VD14; Among them, 1.9100≤|VD7 / VD8|≤2.9500, 4.6800≤VD13 / VD14≤5.3000.

5. The industrial lens according to claim 1, characterized in that: The total optical length of the industrial lens is TTL, the focal length is EFL, the maximum effective aperture is DM, the image plane size is IM, the working F number is FNO, and the field of view angle is FOV; Among them, 17.5200≤TTL / EFL≤17.6500, 2.0400≤TTL / DM≤2.0600, 3.0500≤IM / FNO≤3.0700, FOV≥96.3700°.

6. The industrial lens according to claim 1, characterized in that: The refractive index Nd1 of the first lens satisfies Nd1≥1.9300.

7. The industrial lens according to claim 1, characterized in that: The industrial lens further comprises an aperture, which is arranged in the optical path between the eleventh lens and the twelfth lens; The focal power of the lens group formed by the ninth lens, the tenth lens and the eleventh lens is ΦZ1, the focal power of the lens group formed by the twelfth lens, the thirteenth lens and the fourteenth lens is ΦZ2, and the maximum optical distortion of the industrial lens is DISG.MAX; Among them, -0.9600≤ΦZ1 / ΦZ2≤-0.7500; 0≤|DISG.MAX|≤0.500%.

8. The industrial lens according to claim 1, characterized in that: The shape factor of the fourth lens is ξ4, and the minimum value of the full-field relative illumination of the industrial lens is RI.MIN; Among them, 6.0400≤|ξ4|≤12.1400; 84.2000%≤RI.MIN.

9. The industrial lens according to claim 1, characterized in that: The first lens comprises a first object-side surface close to the object plane and a first image-side surface close to the image plane, the first object-side surface is a convex surface, and the first image-side surface is a concave surface; The second lens comprises a second object-side surface close to the object plane and a second image-side surface close to the image plane, the second object-side surface is a convex surface, and the second image-side surface is a concave surface; The third lens comprises a third object-side surface close to the object plane and a third image-side surface close to the image plane, the third object-side surface is a concave surface, and the third image-side surface is a concave surface; The fourth lens comprises a fourth object-side surface close to the object plane and a fourth image-side surface close to the image plane, the fourth object-side surface is a concave surface, and the fourth image-side surface is a convex surface; The fifth lens comprises a fifth object-side surface close to the object plane and a fifth image-side surface close to the image plane, the fifth object-side surface is a concave surface, and the fifth image-side surface is a convex surface; The sixth lens comprises a sixth object-side surface close to the object plane and a sixth image-side surface close to the image plane, the sixth object-side surface is a concave surface, and the sixth image-side surface is a convex surface; The seventh lens comprises a seventh object-side surface close to the object plane and a seventh image-side surface close to the image plane, the seventh object-side surface is a concave surface or a convex surface, and the seventh image-side surface is a concave surface or a convex surface; The eighth lens comprises an eighth object-side surface close to the object plane and an eighth image-side surface close to the image plane, the eighth object-side surface is a convex surface or a concave surface, and the eighth image-side surface is a convex surface; The ninth lens comprises a ninth object-side surface close to the object plane and a ninth image-side surface close to the image plane, the ninth object-side surface is a convex surface, and the ninth image-side surface is a concave surface or a convex surface; The tenth lens comprises a tenth object-side surface close to the object plane and a tenth image-side surface close to the image plane, the tenth object-side surface is a convex surface, and the tenth image-side surface is a concave surface; The eleventh lens comprises an eleventh object-side surface close to the object plane and an eleventh image-side surface close to the image plane, the eleventh object-side surface is a convex surface, and the eleventh image-side surface is a concave surface or a convex surface; The twelfth lens comprises a twelfth object-side surface close to the object plane and a twelfth image-side surface close to the image plane, the twelfth object-side surface is a convex surface, and the twelfth image-side surface is a concave surface; The thirteenth lens comprises a thirteenth object-side surface close to the object plane and a thirteenth image-side surface close to the image plane, the thirteenth object-side surface is a convex surface, and the thirteenth image-side surface is a convex surface; The fourteenth lens comprises a fourteenth object-side surface close to the object plane and a fourteenth image-side surface close to the image plane, the fourteenth object-side surface is a concave surface, and the fourteenth image-side surface is a concave surface or a convex surface; The fifteenth lens includes a fifteenth object-side surface close to the object plane and a fifteenth image-side surface close to the image plane. The fifteenth object-side surface is a convex surface, and the fifteenth image-side surface is a convex surface.

10. The industrial lens according to claim 1, characterized in that: The first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens, the thirteenth lens, and the fourteenth lens are all glass spherical lenses; The second lens and the fifteenth lens are both glass aspherical lenses.

Images