Large-target-surface industrial lens

Abstract

The invention discloses a large-target-surface industrial lens. Comprising a first lens with positive focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with negative focal power and an eighth lens with positive focal power which are sequentially arranged along an optical axis, the system comprises a first lens with positive focal power, a second lens with positive focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power, a sixth lens with positive focal power, a ninth lens with positive focal power, a diaphragm, a tenth lens with negative focal power, an eleventh lens with positive focal power, a twelfth lens with positive focal power, a thirteenth lens with negative focal power, and a fourteenth lens with negative focal power. The third lens and the fourteenth lens are glass aspheric lenses, and the rest lenses are glass spherical lenses. Through reasonable glass material selection and focal power distribution, collaborative optimization of a 4 / 3'inch super-large target surface, an image space F # 2.0 large aperture, high resolution and low distortion is realized, and a reliable solution is provided for a next-generation industrial visual system.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical lenses, and in particular to a large-surface industrial lens. Background Art

[0002] As a core component of machine vision systems, the optical performance of industrial lenses directly impacts image quality and detection accuracy. With the rapid development of intelligent manufacturing, semiconductor inspection, and high-precision measurement, the market is placing more stringent technical requirements on industrial lenses.

[0003] The current industrial lens has a small target surface, making it difficult to match high-resolution sensors and large apertures. It cannot meet the signal-to-noise ratio requirements in low-light environments, and cannot take into account both high resolution and low distortion to ensure deformation control of the edge field of view. Summary of the Invention

[0004] The present invention provides a large-target-area industrial lens. By using glass aspheric surfaces and anomalous dispersion glass, the lens achieves a 4 / 3-inch ultra-large target area, a large aperture of F#2.0 on the image side, and the coordinated optimization of high resolution and low distortion while controlling the number of lenses. This provides a reliable optical solution for the next generation of industrial vision systems.

[0005] An embodiment of the present invention provides a large-surface industrial lens, comprising a compensation group, a focus group, and a diaphragm arranged in sequence along an optical axis;

[0006] The compensation group includes a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, and a sixth lens with positive optical power, which are arranged in sequence along the optical axis;

[0007] The focusing group includes a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, a tenth lens with negative optical power, an eleventh lens with positive optical power, a twelfth lens with positive optical power, a thirteenth lens with negative optical power, and a fourteenth lens with negative optical power, arranged in sequence along the optical axis;

[0008] The aperture is located between the ninth lens and the tenth lens;

[0009] Among the first to fourteenth lenses, the third lens and the fourteenth lens are glass aspherical lenses, and the remaining lenses are glass spherical lenses.

[0010] Optionally, the second lens and the third lens meet the following conditions: 40 <VD3<85;

[0011] in, is the optical power of the second lens, is the optical power of the third lens, and VD3 is the Abbe constant of the third lens.

[0012] Optionally, the fourth lens and the fifth lens are cemented together to form a first doublet lens group.

[0013] Optionally, the fourth lens and the fifth lens meet the following conditions:

[0014]

[0015] in, is the optical power of the fourth lens, is the optical power of the fifth lens, VD4 is the Abbe constant of the fourth lens, VD5 is the Abbe constant of the fifth lens, is the optical power of the large-target industrial lens.

[0016] Optionally, the seventh lens, the eighth lens, and the ninth lens meet the following conditions:

[0017]

[0018] in, is the focal power of the seventh lens, is the focal power of the eighth lens, is the focal length of the ninth lens, VD7 is the Abbe constant of the seventh lens, VD8 is the Abbe constant of the eighth lens, and VD9 is the Abbe constant of the ninth lens. is the optical power of the large-target industrial lens.

[0019] Optionally, the tenth lens and the eleventh lens are cemented together to form a second doublet lens group.

[0020] Optionally, the tenth lens and the eleventh lens meet the following conditions:

[0021]

[0022] in, is the optical power of the second doublet lens group, is the optical power of the tenth lens, is the optical power of the eleventh lens, VD10 is the Abbe constant of the tenth lens, and VD11 is the Abbe constant of the eleventh lens.

[0023] Optionally, the twelfth lens and the thirteenth lens are cemented together to form a third doublet lens group.

[0024] Optionally, the twelfth lens, the thirteenth lens, and the fourteenth lens meet the following conditions:

[0025]

[0026] in, is the focal power of the twelfth lens, is the optical power of the thirteenth lens, is the optical power of the fourteenth lens, ND12 is the refractive index of the twelfth lens, ND13 is the refractive index of the thirteenth lens, is the optical power of the large-target industrial lens.

[0027] Optionally, the large-area industrial lens meets the following conditions: 2 <SDmax / H<2.4,8<TTL / f<9.5;

[0028] Among them, SDmax is the maximum aperture of the lens in the large-target-area industrial lens, H is the maximum image height of the large-target-area industrial lens, TTL is the distance from the midpoint of the object side of the first lens to the midpoint of the imaging surface, and f is the focal length of the large-target-area industrial lens.

[0029] An industrial lens with a large image area according to an embodiment of the present invention includes a compensation group, a focusing group, and an aperture arranged in sequence along an optical axis. The compensation group includes a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, and a sixth lens with positive optical power. The focusing group includes a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, a tenth lens with negative optical power, an eleventh lens with positive optical power, a twelfth lens with positive optical power, a thirteenth lens with negative optical power, and a fourteenth lens with negative optical power. The aperture is located between the ninth and tenth lenses. Of the first to fourteenth lenses, the third and fourteenth lenses are glass aspherical lenses, and the remaining lenses are glass spherical lenses. Through the rational selection of glass materials and the appropriate distribution of lens power, an optical structure comprising fourteen lenses achieves a focal length of approximately 12mm at an optimal working distance of 300mm, optical distortion <0.3%, an image-space F# of 2, a maximum half-image height of 11.5mm, and rear-group focus adjustment for object distances from 100mm to 1000mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of a large-target-area industrial lens provided in the first embodiment of the present invention;

[0031] Figure 2 for Figure 1The full-frequency MTF diagram of the visible light band of the large-area industrial lens shown in the figure;

[0032] Figure 3 for Figure 1 The axial chromatic aberration curve of the large-surface industrial lens is shown;

[0033] Figure 4 for Figure 1 The field area and distortion diagram of the large-area industrial lens shown;

[0034] Figure 5 This is a schematic structural diagram of a large-target-area industrial lens provided by the second embodiment of the present invention;

[0035] Figure 6 for Figure 5 The full-frequency MTF diagram of the visible light band of the large-area industrial lens shown in the figure;

[0036] Figure 7 for Figure 5 The axial chromatic aberration curve of the large-surface industrial lens is shown;

[0037] Figure 8 for Figure 5 The field area and distortion diagram of the large-area industrial lens shown;

[0038] Figure 9 This is a schematic structural diagram of a large-target-area industrial lens provided by the third embodiment of the present invention;

[0039] Figure 10 for Figure 9 The full-frequency MTF diagram of the visible light band of the large-area industrial lens shown in the figure;

[0040] Figure 11 for Figure 9 The axial chromatic aberration curve of the large-surface industrial lens is shown;

[0041] Figure 12 for Figure 9 The field of view and distortion diagram of the large-area industrial lens shown. DETAILED DESCRIPTION

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0043] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described based on the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be formed directly "on" or "under" another element, but can also be formed indirectly "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not indicate any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The term "including" and its variations used in the present invention are open inclusions, that is, "including but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment."

[0045] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or mutual dependence.

[0046] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0047] Figure 1 This is a schematic diagram of the structure of a large-surface industrial lens provided by the first embodiment of the present invention, with reference to Figure 1 The large-surface industrial lens includes a compensation group G1, a focusing group G2 and a stop STO arranged in sequence along the optical axis.

[0048] The compensation group G1 includes a first lens 1 with positive focal power, a second lens 2 with negative focal power, a third lens 3 with negative focal power, a fourth lens 4 with positive focal power, a fifth lens 5 with negative focal power, and a sixth lens 6 with positive focal power, which are arranged in sequence along the optical axis; the focusing group G2 includes a seventh lens 7 with negative focal power, an eighth lens 8 with positive focal power, a ninth lens 9 with positive focal power, a tenth lens 10 with negative focal power, an eleventh lens 11 with positive focal power, a twelfth lens 12 with positive focal power, a thirteenth lens 13 with negative focal power, and a fourteenth lens 14 with negative focal power, which are arranged in sequence along the optical axis; the aperture STO is located between the ninth lens 9 and the tenth lens 10.

[0049] Among the first to fourteenth lenses, the third and fourteenth lenses are glass aspherical lenses, and the remaining lenses are glass spherical lenses.

[0050] First of all, it can be understood that the optical focal length is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, which characterizes the ability of the optical system to deflect light. The larger the absolute value of the optical focal length, the stronger the ability to bend light, and the smaller the absolute value of the optical focal length, the weaker the ability to bend light. When the optical focal length is a positive number, the refraction of light is convergent; when the optical focal length is a negative number, the refraction of light is divergent. The optical focal length can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens or lens group, and can also be used to characterize a system composed of multiple lenses (i.e., a group or lens group). It can also be understood that in the field of industrial lenses, in order to ensure clear imaging and stable image plane position within different working distances, i.e., object distances, the focus group and the compensation group need to cooperate to achieve this. The focusing group is used to change the focal length or back focus of the lens' optical system, allowing objects at different distances (object distances) to be clearly imaged on the target surface of the image sensor (CCD / CMOS). In short, the focusing group is responsible for ensuring that the lens can clearly see targets near or far. The compensation group is used to move synchronously along a specific trajectory to offset the negative effects of the focus group's movement. For example, it can maintain image stability: the focal plane is accurately "pulled back" and stabilized at the target surface position of the image sensor, ensuring that the focus always falls on the chip. Another example is correcting aberration changes: it is used to actively correct these aberration changes caused by focusing, thereby maintaining high and consistent image quality (resolution, contrast, low distortion) throughout the entire focus range.

[0051] In the embodiments of the present invention, on the one hand, by setting the third lens 3 and the fourteenth lens 14 as glass aspherical lenses and the remaining lenses as glass spherical lenses, the two glass aspherical lenses at key positions of the entire optical system can be used to effectively correct various aberrations. At the same time, only these two lenses are set as glass aspherical lenses for cost considerations, reducing the processing difficulty and saving the material cost. On the other hand, by setting the aperture stop STO between the ninth lens 9 and the tenth lens 10, it can ensure that a relatively large beam aperture is generated after the light passes through, increasing the aperture of the optical system and meeting the usage requirements under different conditions. All in all, through comprehensive consideration of aberration correction effect, material cost, processing difficulty, material optical properties, etc., the embodiments of the present invention adopt reasonable selection of glass materials and reasonable distribution of lens focal power, and use an optical structure of fourteen lenses to achieve that when the optimal working distance is 300 mm, the lens focal length is about 12 mm, |optical distortion| < 0.3%, the image-side F# number is 2, the maximum semi-image height is 11.5 mm, and the working object distance is focused by group movement from 100 mm to 1000 mm object distance. It should be added that the large target surface industrial lens in the embodiments of the present invention is also provided with a filter F, and the filter F is located on the image side of the fourteenth lens. The filter F can prevent light in non-designed wavelength bands from entering the image sensor.

[0052] In a specific embodiment, optionally, the second lens 2 and the third lens 3 satisfy the following conditions: 40 < VD3 < 85; where is the focal power of the second lens 2, is the focal power of the third lens 3, and VD3 is the Abbe number of the third lens 3.

[0053] Adopting the above conditions is beneficial to reducing the incident angle of light entering the optical system and reducing the lens volume. Among them, the consecutive negative lenses bending towards the aperture stop STO are beneficial to the correction of system distortion.

[0054] In a specific embodiment, optionally, the fourth lens 4 and the fifth lens 5 are mutually cemented to form the first doublet lens group. Further, the fourth lens 4 and the fifth lens 5 satisfy the following conditions: 40 < Vd5 - Vd4 < 60; where is the focal power of the fourth lens 4, is the focal power of the fifth lens 5, VD4 is the Abbe number of the fourth lens 4, VD5 is the Abbe number of the fifth lens 5, is the focal power of the large target surface industrial lens. Adopting the above conditions is beneficial to the correction of the field curvature of the optical system.

[0055] In a specific embodiment, optionally, the seventh lens 7, the eighth lens 8 and the ninth lens 9 satisfy the following conditions: 100 < VD7 + VD8 + VD9 < 130; where, is the optical power of the seventh lens 7, is the optical power of the eighth lens 8, is the optical power of the ninth lens 9, VD7 is the Abbe number of the seventh lens 7, VD8 is the Abbe number of the eighth lens 8, and VD9 is the Abbe number of the ninth lens 9, is the optical power of the large target surface industrial lens. With the above conditions, it is beneficial to reduce the on-axis aberration of the system and improve the resolution of the system.

[0056] In a specific embodiment, optionally, the tenth lens 10 and the eleventh lens 11 are glued together to form the second doublet lens group. Further, the tenth lens 10 and the eleventh lens 11 satisfy the following conditions: where, is the optical power of the second doublet lens group, is the optical power of the tenth lens 10, is the optical power of the eleventh lens 11, VD10 is the Abbe number of the tenth lens 10, and VD11 is the Abbe number of the eleventh lens 11. With the above conditions, it is beneficial for the doublet lens to exert the ability to correct the chromatic aberration of the optical system, thereby improving the resolution of the optical system.

[0057] In a specific embodiment, optionally, the twelfth lens 12 and the thirteenth lens 13 are glued together to form the third doublet lens group. Further, the twelfth lens 12, the thirteenth lens 13, and the fourteenth lens 14 satisfy the following conditions: where, is the optical power of the twelfth lens 12, is the optical power of the thirteenth lens 13, is the optical power of the fourteenth lens 14, ND12 is the refractive index of the twelfth lens 12, ND13 is the refractive index of the thirteenth lens 13, is the optical power of the large target surface industrial lens.

[0058] With the above conditions, it is beneficial to reduce the incident and exit angles of light on the lens surface, correct the off-axis aberration, and improve the resolution of the system.

[0059] In a specific embodiment, optionally, the large target surface industrial lens satisfies the following conditions: 2 < SDmax / H < 2.4, 8 < TTL / f < 9.5; where, SDmax is the maximum aperture of the lens in the large target surface industrial lens, H is the maximum image height of the large target surface industrial lens, TTL is the distance from the midpoint of the object side surface of the first lens to the midpoint of the imaging surface, and f is the focal length of the large target surface industrial lens.

[0060] With the above conditions, it is beneficial to reduce the volume and weight of the overall optical system and adapt to more usage environments.

[0061] Based on the same concept above, the present invention provides three different specific embodiments, whose optical power relationships and related physical optical parameter design ranges are shown in Table 1:

[0062] Table 1 Relationship between the focal powers of the lenses and the design values ​​of relevant physical optical parameters in the three embodiments

[0063]

[0064]

[0065] like Figure 1 The parameter design values ​​of each lens in the large target surface process lens of Example 1 are shown in Table 2:

[0066] Table 2 Design values ​​of each lens in the large-surface industrial lens of Example 1

[0067]

[0068]

[0069] The surface numbers in Table 2 are numbered according to the order of the surfaces of each lens, where "1" represents the front surface of the first lens, "2" represents the back surface of the first lens, and so on. "STO" represents the aperture in the lens. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane, and a negative value indicating that the surface is curved toward the object plane. 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. A blank space represents the current position as air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. dPgF represents local dispersion, a parameter that measures the dispersion characteristics of a material and is used in the design process to eliminate lateral chromatic aberration. The k value represents the numerical value of the best-fit conic coefficient of the aspheric surface.

[0070] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

[0071]

[0072] Where z is the axial sagittal 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 fitted conic coefficient; and AG are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspheric polynomial. The coefficients of the 14th and 16th order terms not shown are assumed to be 0 by default.

[0073] The even-order coefficients of each aspheric surface in the above embodiment 1 are shown in Table 3:

[0074] Table 3 Aspheric parameters of each lens in the large-area industrial lens of Example 1

[0075] Surface number A B C D E 6 -3.010369E-05 2.973035E-08 -3.805100E-12 1.093966E-13 -2.602133E-16 7 -6.120579E-05 -1.663092E-07 -1.029220E-10 2.232797E-12 -1.009092E-14 27 -3.421381E-04 2.266628E-06 3.558135E-09 -1.836836E-10 1.033322E-12 28 -2.055429E-04 1.715076E-06 1.043629E-08 -2.616591E-10 1.455051E-12

[0076] Among them, -3.010369E-05 means that the coefficient A of face number 6 is -3.010369*10 -5 , and so on.

[0077] The thickness of the focus interval at different object distances in Table 1 above is shown in Table 4:

[0078] Table 4 Thickness of focus interval at different object distances in Example 1

[0079] Object distance / mm 100 300 1000 Surface number 13 thickness / mm 0.2963 1.042 1.3691 Surface number 31 thickness / mm -0.2963 -1.042 -1.3691

[0080] Figure 2 for Figure 1 The full-frequency MTF diagram of the visible light band of the large-area industrial lens shown is shown in the figure. Figure 2 , where the vertical axis represents the modulation transfer function (MTF) and the horizontal axis represents the frequency. The simulated wavelength range is 460nm to 620nm. Figure 2 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all greater than 0.3 in the 150lp / mm frequency band, indicating that the image quality of this large-area industrial lens is well controlled.

[0081] Figure 3 for Figure 1 The axial chromatic aberration curve of the large image surface industrial lens is shown in the figure. Figure 3 , where the vertical direction represents the normalized aperture, 0 represents the optical axis, and the vertex in the vertical axis represents the maximum pupil radius; the horizontal direction represents the offset relative to the main wavelength, in millimeters (mm). Figure 3 It can be seen that at different wavelengths (620nm, 530nm, 460nm), the axial aberration of the normalized aperture is controlled within a reasonable range, indicating that the axial chromatic aberration of this large-scale industrial lens is well controlled and meets the usage requirements.

[0082] Figure 4 for Figure 1 The field area and distortion diagram of the large-area industrial lens shown in the figure are referenced Figure 4 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; T represents the meridian, and S represents the arc loss; Figure 4It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled at a wavelength of 460nm. That is, when imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the degree of distortion, in units of %, and the vertical coordinate represents the normalized image height, without units.

[0083] Figure 5 This is a schematic diagram of the structure of a large-surface industrial lens provided by the second embodiment of the present invention, with reference to Figure 5 The parameter design values ​​of each lens in the large-surface industrial lens of the second embodiment are shown in Table 5:

[0084] Table 5: Design values ​​of each lens in the large-area industrial lens of Example 2

[0085]

[0086]

[0087] The surface numbers in Table 5 are numbered according to the order of the surfaces of each lens, where "1" represents the front surface of the first lens, "2" represents the back surface of the first lens, and so on. "STO" represents the aperture in the lens. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane, and a negative value indicating that the surface is curved toward the object plane. 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. A blank space represents the current position as air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. dPgF represents local dispersion, a parameter that measures the dispersion characteristics of a material and is used in the design process to eliminate lateral chromatic aberration. The k value represents the numerical value of the best-fit conic coefficient of the aspheric surface.

[0088] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

[0089]

[0090] Where z is the axial sagittal 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 fitted conic coefficient; and AG are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspheric polynomial. The coefficients of the 14th and 16th order terms not shown are assumed to be 0 by default.

[0091] The even-order coefficients of each aspheric surface in the above-mentioned embodiment 2 are shown in Table 6:

[0092] Table 6 Aspheric parameters of each lens in the large-area industrial lens of Example 2

[0093] Surface number A B C D E 6 -1.108012E-05 -4.684824E-08 1.475704E-10 4.492862E-13 -1.497726E-15 7 -8.880323E-05 -9.929069E-08 -8.795879E-10 7.396640E-12 -2.340944E-14 27 -2.822989E-04 2.586549E-06 -1.540714E-08 7.576793E-11 -8.710105E-14 28 -2.072166E-04 2.572371E-06 -1.756396E-08 8.658611E-11 -5.296664E-14

[0094] Among them, -1.108012E-05 means that the coefficient A of face number 6 is -1.108012*10 -5 , and so on.

[0095] The thickness of the focus interval at different object distances in Table 5 above is shown in Table 7:

[0096] Table 7 Thickness of focus interval at different object distances in Example 2

[0097] Object distance / mm 100 300 1000 Surface number 13 thickness / mm 0.3 0.945 1.2412 Surface number 31 thickness / mm -0.3 -0.945 -1.2412

[0098] Figure 6 for Figure 5 The full-frequency MTF diagram of the visible light band of the large-area industrial lens shown is shown in the figure. Figure 6 , where the vertical axis represents the modulation transfer function (MTF) and the horizontal axis represents the frequency. The simulated wavelength range is 460nm to 620nm. Figure 6 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all greater than 0.3 in the 150lp / mm frequency band, indicating that the image quality of this large-area industrial lens is well controlled.

[0099] Figure 7 for Figure 5 The axial chromatic aberration curve of the large image surface industrial lens is shown in the figure. Figure 7 , where the vertical direction represents the normalized aperture, 0 represents the optical axis, and the vertex in the vertical axis represents the maximum pupil radius; the horizontal direction represents the offset relative to the main wavelength, in millimeters (mm). Figure 7 It can be seen that at different wavelengths (620nm, 530nm, 460nm), the axial aberration of the normalized aperture is controlled within a reasonable range, indicating that the axial chromatic aberration of this large-scale industrial lens is well controlled and meets the usage requirements.

[0100] Figure 8 for Figure 5 The field area and distortion diagram of the large-area industrial lens shown in the figure are referenced Figure 8 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; T represents the meridian, and S represents the arc loss; Figure 8 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled at a wavelength of 460nm. That is, when imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the degree of distortion, in units of %, and the vertical coordinate represents the normalized image height, without units.

[0101] Figure 9This is a schematic diagram of the structure of a large-surface industrial lens provided by the third embodiment of the present invention, with reference to Figure 9 The parameter design values ​​of each lens in the large-surface industrial lens of the third embodiment are shown in Table 8:

[0102] Table 8: Design values ​​of each lens in the large-area industrial lens of Example 3

[0103]

[0104]

[0105] The surface numbers in Table 8 are numbered according to the order of the surfaces of each lens, where "1" represents the front surface of the first lens, "2" represents the back surface of the first lens, and so on. "STO" represents the aperture in the lens. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane, and a negative value indicating that the surface is curved toward the object plane. 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. A blank space represents the current position as air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. dPgF represents local dispersion, a parameter that measures the dispersion characteristics of a material and is used in the design process to eliminate lateral chromatic aberration. The k value represents the numerical value of the best-fit conic coefficient of the aspheric surface.

[0106] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

[0107]

[0108] Where z is the axial sagittal 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 fitted conic coefficient; and AG are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspheric polynomial. The coefficients of the 14th and 16th order terms not shown are assumed to be 0 by default.

[0109] The even-order coefficients of each aspheric surface in the third embodiment are shown in Table 9:

[0110] Table 9 Aspheric parameters of each lens in the large-area industrial lens of Example 3

[0111] Surface number A B C D E 6 -2.030241E-05 -5.961184E-08 2.868950E-10 5.649621E-17 -1.154541E-15 7 -5.252653E-05 -2.457760E-07 -4.510092E-10 6.409942E-12 -2.284848E-14 27 -2.373212E-04 2.083505E-06 -1.268898E-08 5.892599E-11 -8.241924E-14 28 -1.555523E-04 2.377708E-06 -2.036013E-08 1.307607E-10 -3.028694E-13

[0112] Among them, -2.030241E-05 means that the coefficient A of face number 6 is -2.030241*10 -5 , and so on.

[0113] The thickness of the focus interval at different object distances in Table 8 above is shown in Table 10:

[0114] Table 10 Thickness of focus interval at different object distances in Example 3

[0115] Object distance / mm 100 300 1000 Surface number 13 thickness / mm 0.3 0.985 1.2986 Surface number 31 thickness / mm -0.3 -0.985 -1.2986

[0116] Figure 10 for Figure 9 The full-frequency MTF diagram of the visible light band of the large-area industrial lens shown is shown in the figure. Figure 10 , where the vertical axis represents the modulation transfer function (MTF) and the horizontal axis represents the frequency. The simulated wavelength range is 460nm to 620nm. Figure 10 It can be seen that the modulation transfer function values ​​of each frequency under different fields of view are all controlled within a reasonable range. The modulation transfer function values ​​in the entire field of view are all greater than 0.3 in the 150lp / mm frequency band, indicating that the image quality of this large-area industrial lens is well controlled.

[0117] Figure 11 for Figure 9 The axial chromatic aberration curve of the large image surface industrial lens is shown in the figure. Figure 11 , where the vertical direction represents the normalized aperture, 0 represents the optical axis, and the vertex in the vertical axis represents the maximum pupil radius; the horizontal direction represents the offset relative to the main wavelength, in millimeters (mm). Figure 11 It can be seen that at different wavelengths (620nm, 530nm, 460nm), the axial aberration of the normalized aperture is controlled within a reasonable range, indicating that the axial chromatic aberration of this large-scale industrial lens is well controlled and meets the usage requirements.

[0118] Figure 12 for Figure 9 The field area and distortion diagram of the large-area industrial lens shown in the figure are referenced Figure 12 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; T represents the meridian, and S represents the arc loss; Figure 12 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled at a wavelength of 460nm. That is, when imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the degree of distortion, in units of %, and the vertical coordinate represents the normalized image height, without units.

[0119] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A large-area industrial lens, characterized in that: It includes a compensation group, a focus group and an aperture arranged in sequence along the optical axis; The compensation group includes a first lens with positive optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, and a sixth lens with positive optical power, which are arranged in sequence along the optical axis; The focusing group includes a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, a tenth lens with negative optical power, an eleventh lens with positive optical power, a twelfth lens with positive optical power, a thirteenth lens with negative optical power, and a fourteenth lens with negative optical power, arranged in sequence along the optical axis; The aperture is located between the ninth lens and the tenth lens; Among the first to fourteenth lenses, the third lens and the fourteenth lens are glass aspherical lenses, and the remaining lenses are glass spherical lenses.

2. The large-area industrial lens according to claim 1, characterized in that: The second lens and the third lens meet the following conditions: -1<φ2 / φ+φ3 / φ<-0.85; 40 <VD3<85; Wherein, φ2 is the focal length of the second lens, φ3 is the focal length of the third lens, and VD3 is the Abbe constant of the third lens.

3. The large-area industrial lens according to claim 1, characterized in that: The fourth lens and the fifth lens are cemented together to form a first doublet lens group.

4. The large-area industrial lens according to claim 3, characterized in that: The fourth lens and the fifth lens meet the following conditions: 0.3<φ4 / φ<0.6, 0.2<|φ5 / φ|<0.5, 40 <Vd5-Vd4<60; Among them, φ4 is the optical power of the fourth lens, φ5 is the optical power of the fifth lens, VD4 is the Abbe constant of the fourth lens, VD5 is the Abbe constant of the fifth lens, and φ is the optical power of the large-target-area industrial lens.

5. The large-area industrial lens according to claim 1, characterized in that: The seventh lens, the eighth lens, and the ninth lens meet the following conditions: 0.2<φ7 / φ+φ8 / φ+φ9 / φ<0.5, 100 <VD7+VD8+VD9<130; Among them, φ7 is the optical focal length of the seventh lens, φ8 is the optical focal length of the eighth lens, φ9 is the optical focal length of the ninth lens, VD7 is the Abbe constant of the seventh lens, VD8 is the Abbe constant of the eighth lens, VD9 is the Abbe constant of the ninth lens, and φ is the optical focal length of the large-target industrial lens.

6. The large-area industrial lens according to claim 1, characterized in that: The tenth lens and the eleventh lens are cemented together to form a second doublet lens group.

7. The large-area industrial lens according to claim 6, characterized in that: The tenth lens and the eleventh lens satisfy the following conditions: 100*|φ10+φ11-φ10_11|<0.5, 100*|φ10 / VD10+φ11 / VD11|<0.5; Wherein, φ10_11 is the optical power of the second doublet lens group, φ10 is the optical power of the tenth lens, φ11 is the optical power of the eleventh lens, VD10 is the Abbe constant of the tenth lens, and VD11 is the Abbe constant of the eleventh lens.

8. The large-area industrial lens according to claim 1, characterized in that: The twelfth lens and the thirteenth lens are cemented together to form a third doublet lens group.

9. The large-area industrial lens according to claim 8, characterized in that: The twelfth lens, the thirteenth lens, and the fourteenth lens meet the following conditions: 0.2<φ12 / φ+φ13 / φ+φ14 / φ<0.5, 3.3 <ND12+ND13<4; Among them, φ12 is the optical focal length of the twelfth lens, φ13 is the optical focal length of the thirteenth lens, φ14 is the optical focal length of the fourteenth lens, ND12 is the refractive index of the twelfth lens, ND13 is the refractive index of the thirteenth lens, and φ is the optical focal length of the large-target industrial lens.

10. The large-area industrial lens according to claim 1, characterized in that: The large-area industrial lens meets the following conditions: 2 <SDmax / H<2.4,8<TTL / f<9.5; Among them, SDmax is the maximum aperture of the lens in the large-target-area industrial lens, H is the maximum image height of the large-target-area industrial lens, TTL is the distance from the midpoint of the object side of the first lens to the midpoint of the imaging surface, and f is the focal length of the large-target-area industrial lens.

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