Industrial lens

Abstract

The application discloses an industrial lens, which comprises, in sequence from the object side to the imaging surface along the optical axis, a first lens with positive focal length, the object side of which is a convex surface; a second lens with positive focal length, the object side of which is a convex surface and the image side of which is a concave surface; a third lens with negative focal length, the image side of which is a concave surface; a voltage-driven zoom lens; a diaphragm; a fourth lens with negative focal length, the object side of which is a concave surface and the image side of which is a concave surface; a fifth lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface; and a sixth lens with positive focal length, the object side of which is a convex surface and the image side of which is a convex surface. The industrial lens of the application adopts the combination of six spherical lenses and one voltage-driven zoom lens, and can ensure good image quality when used at different object distances.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lens, in particular to an industrial lens. BACKGROUND

[0002] In recent years, with the development of automation industry, machine vision has achieved explosive growth, and the application field of industrial lens is also more and more extensive. Because the industrial lens has the characteristics of high resolution, high definition and good stability, it is widely used in size measurement, defect detection, image acquisition and other fields.

[0003] In order to realize good imaging effect, such industrial lens usually requires high resolution, small picture distortion degree, and high relative luminance to ensure the uniformity of picture luminance. At the same time, in order to make the lens have good imaging effect at different working distances, the lens needs to collect images of different working distances through focusing. The focusing mode of traditional lens is realized based on mechanical movement, such as installing motor in the lens, the motor can drive the lens or lens group to move transversely along the optical axis, so as to change the optical interval between the lens or between the lens and the camera chip, thereby compensating for the shift of imaging focus point of the lens caused by the change of working distance.

[0004] However, such mechanical focusing lens has slow focusing speed, needs manual focusing, and has large volume, which is difficult to meet the use demand of application scene with high real-time requirement. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an industrial lens with fast focusing speed and high imaging quality.

[0006] In order to achieve the above purpose, the technical scheme of the present application is as follows:

[0007] The present application provides an industrial lens, which comprises, in sequence along the optical axis from the object side to the imaging surface: a first lens with positive focal power, the object side surface of the first lens being convex; a second lens with positive focal power, the object side surface of the second lens being convex, and the image side surface of the second lens being concave; a third lens with negative focal power, the image side surface of the third lens being concave; a voltage driven zoom lens; a diaphragm; a fourth lens with negative focal power, the object side surface of the fourth lens being concave, and the image side surface of the fourth lens being concave; a fifth lens with positive focal power, the object side surface of the fifth lens being convex, and the image side surface of the fifth lens being convex; a sixth lens with positive focal power, the object side surface of the sixth lens being convex, and the image side surface of the sixth lens being convex; wherein the industrial lens satisfies the following conditional expression: 0.8<|f min / f max <1.5; wherein f minrepresents a minimum imaging focal length of the industrial lens, f max represents a maximum imaging focal length of the industrial lens.

[0008] Compared with the prior art, the present application adopts 6 pieces of lenses with specific optical power and surface type and 1 piece of voltage-driven zoom lens, can not only realize fast focusing, so that the lens can have super high resolution under different object distances, can well meet the use requirements of the application scene with relatively high real-time requirement, but also reduces the weight of the lens, realizes the light weight of the lens, meets the requirements of high image quality and small distortion of the industrial lens. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 a structural schematic diagram of an industrial lens provided for the first embodiment of the present application is shown;

[0010] Figure 2 a distortion curve diagram of the industrial lens provided for the first embodiment of the present application is shown;

[0011] Figure 3 an MTF diagram of the industrial lens provided for the first embodiment of the present application is shown;

[0012] Figure 4 a vertical axis chromatic aberration curve diagram of the industrial lens provided for the first embodiment of the present application is shown;

[0013] Figure 5 a structural schematic diagram of an industrial lens provided for the second embodiment of the present application is shown;

[0014] Figure 6 a distortion curve diagram of the industrial lens provided for the second embodiment of the present application is shown;

[0015] Figure 7 an MTF diagram of the industrial lens provided for the second embodiment of the present application is shown;

[0016] Figure 8 a vertical axis chromatic aberration curve diagram of the industrial lens provided for the second embodiment of the present application is shown;

[0017] Figure 9 a structural schematic diagram of an industrial lens provided for the third embodiment of the present application is shown;

[0018] Figure 10 a distortion curve diagram of the industrial lens provided for the third embodiment of the present application is shown;

[0019] Figure 11 an MTF diagram of the industrial lens provided for the third embodiment of the present application is shown;

[0020] Figure 12 a vertical axis chromatic aberration curve diagram of the industrial lens provided for the third embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] In order to make the objects, features and advantages of the present application more clear, the detailed description of the specific embodiments of the present application is given below with reference to the accompanying drawings. Several embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided for the purpose of making the disclosure of the present application more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.

[0023] The present application provides an industrial lens, which comprises, in order from the object side to the image plane along the optical axis, a first lens, a second lens, a third lens, a voltage-driven zoom lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a filter, and the optical centers of the lenses are located on the same line.

[0024] The first lens has positive refractive power, and the object side surface of the first lens is convex;

[0025] The second lens has positive refractive power, the object side surface of the second lens is convex, and the image side surface of the second lens is concave;

[0026] The third lens has negative refractive power, and the image side surface of the third lens is concave;

[0027] The voltage-driven zoom lens presents different focal lengths according to different applied voltages;

[0028] The diaphragm;

[0029] The fourth lens has negative refractive power, the object side surface of the fourth lens is concave, and the image side surface of the fourth lens is concave;

[0030] The fifth lens has positive refractive power, the object side surface of the fifth lens is convex, the image side surface of the fifth lens is convex, and the fourth lens and the fifth lens form a cemented lens;

[0031] The sixth lens has positive refractive power, the object side surface of the sixth lens is convex, and the image side surface of the sixth lens is convex.

[0032] The voltage-driven zoom lens is a lens based on a special material, which is a special conductive material. By applying power to the special material, the curvature radius and other parameters of the lens can be changed, and the zoom function of the lens can be realized. When the industrial lens is working, a starting voltage is applied to the voltage-driven zoom lens. At this time, the voltage-driven zoom lens is in the initial working state, and the industrial lens is also in the best working distance of the object distance. When the working object distance of the industrial lens changes within the preset working range, the voltage applied to the voltage-driven zoom lens is automatically adjusted to change the focal length of the voltage-driven zoom lens, thereby changing the focal length of the entire optical system to achieve a better image quality at different object distances. At the same time, by using the voltage-driven zoom lens, compared with the traditional zoom system, the lens has lighter weight, smaller size and faster zoom speed.

[0033] The diaphragm is located between the voltage-driven zoom lens and the fourth lens, which can effectively improve the field angle of the industrial lens and better match the incident angle of the chip.

[0034] In some embodiments, the industrial lens also satisfies the following conditional expression:

[0035] 0.8<|f min / f max |<1.5; (1)

[0036] wherein f min represents the minimum imaging focal length of the industrial lens, and f max represents the maximum imaging focal length of the industrial lens. By reasonably controlling the ratio of the minimum imaging focal length to the maximum imaging focal length of the optical system, the optical power of the optical system can be reasonably distributed, so that the lens has good imaging quality and reduces sensitivity.

[0037] In some embodiments, the industrial lens also satisfies the following conditional expression:

[0038] 0.25<CT45 / CT36<0.5; (2)

[0039] wherein CT45 represents the distance on the optical axis from the image side surface of the second lens to the object side surface of the third lens; and CT36 represents the distance on the optical axis from the object side surface of the second lens to the image side surface of the third lens. Satisfying the above conditional expression (2) is conducive to the correction of coma, so that the lens obtains better image quality.

[0040] In some embodiments, the industrial lens also satisfies the following conditional expression:

[0041] 0.1<CT34 / TTL<0.3; (3)

[0042] Wherein, CT34 represents the air gap between the third lens and the fourth lens on the optical axis, and TTL represents the total optical length of the industrial lens. Satisfying the above condition formula (3), the size of the air gap before and after the voltage-driven zoom lens can be effectively controlled, so that the industrial lens can meet the assembly conditions of the voltage-driven zoom lens and also maintain good overall resolving power.

[0043] In some embodiments, the industrial lens also satisfies the following condition formula:

[0044] 1 < DT11 / DT61 < 2; (4)

[0045] Wherein, DT11 represents the maximum effective diameter of the object side of the first lens, and DT61 represents the maximum effective diameter of the object side of the sixth lens. Satisfying the above condition formula (4), by controlling the ratio of the maximum effective diameter of the object side of the first lens to the maximum effective diameter of the object side of the sixth lens, the size of the lens can be reduced, the lens can be miniaturized, and the resolving power of the lens can be improved.

[0046] In some embodiments, the industrial lens also satisfies the following condition formula:

[0047] 20 < |VD4-VD5| < 40; (5)

[0048] 0.01 < |ND4-ND5| < 0.09; (6)

[0049] Wherein, VD4 represents the Abbe number of the fourth lens, VD5 represents the Abbe number of the fifth lens, ND4 represents the refractive index of the fourth lens, and ND5 represents the refractive index of the fifth lens. Satisfying the above condition formulas (5) and (6), by matching high and low dispersion materials, the system aberration can be optimized, and the imaging quality of the lens can be improved.

[0050] In some embodiments, the industrial lens also satisfies the following condition formula:

[0051] |Φ21 / R21-Φ22 / R22| / 4 > 0.1; (7)

[0052] Wherein, Φ21 represents the effective clear aperture of the object side of the second lens, R21 represents the curvature radius of the object side of the second lens, Φ22 represents the effective clear aperture of the image side of the second lens, and R22 represents the curvature radius of the image side of the second lens. Satisfying the above condition formula (7), the processing difficulty of the second lens can be reduced, and the yield of the lens can be improved.

[0053] In some embodiments, the industrial lens also satisfies the following condition formula:

[0054] 0.2 < IH / TTL < 0.4; (8)

[0055] Wherein, TTL represents the total optical length of the industrial lens, and IH represents the image height of the industrial lens. When the value of IH / TTL exceeds the lower limit, the lens aberration correction is difficult due to the excessive power of each lens, and the resolving power is significantly reduced. When the value of IH / TTL exceeds the upper limit, the total length of the lens is too long, and it is difficult to meet the miniaturization requirement. Or the target surface is too small in the case of a total length small enough, and it is difficult to match a larger chip.

[0056] In some embodiments, the industrial lens further satisfies the following conditional expression:

[0057] 1.5 < U / f < 3.8; (9)

[0058] Wherein, U represents the voltage of the voltage-driven zoom lens at the working object distance, and f represents the effective focal length of the industrial lens. Satisfying the above conditional expression (9), better image quality can be obtained at different working object distances.

[0059] In some embodiments, the industrial lens further satisfies the following conditional expression:

[0060] 0.8 < (f4+f5+f6) / f < 1.2; (10)

[0061] Wherein, f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, and f represents the effective focal length of the industrial lens. Satisfying the above conditional expression (10), the fourth lens to the sixth lens can bear the main optical power of the optical system, the refractive power of each lens can cooperate with each other, which is helpful for the correction of the spherical aberration of the optical system, and better resolving power can be provided.

[0062] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical lenses.

[0063] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens can be made of glass-plastic hybrid materials, or all made of glass material lenses or all made of plastic material lenses.

[0064] The application will be further described in the following embodiments. In each embodiment, the thickness, the radius of curvature, and the material selection of each lens in the industrial lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the application, but the embodiments of the application are not limited to the following embodiments only, and any changes, substitutions, combinations or simplifications made without departing from the innovative points of the application should be regarded as equivalent replacement methods, and are included in the protection scope of the application.

[0065] First embodiment

[0066] AsFigure 1 The diagram shown is a structural schematic of an industrial lens 100 provided in the first embodiment of the present invention. The industrial lens 100 includes, along the optical axis from the object side to the imaging surface, the following components in sequence: a first lens L1, a second lens L2, a third lens L3, a voltage-driven zoom lens L4, an aperture ST, a fourth lens L5, a fifth lens L6, a sixth lens L7, and a filter G1. The optical centers of each lens are located on the same straight line.

[0067] The first lens L1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being planar.

[0068] The second lens L2 has positive optical power, and its object side S3 is convex and its image side S4 is concave.

[0069] The third lens L3 has negative optical power, and its object side S5 is a plane and its image side S6 is a concave surface;

[0070] Voltage-driven zoom lens L4;

[0071] Aperture ST;

[0072] The fourth lens L5 has negative optical power, and its object side S7 is concave and its image side is concave.

[0073] The fifth lens L6 has positive optical power, and its object side and image side S9 are convex. The fourth lens L4 and the fifth lens L5 form a cemented lens body, and their cementing surface is S8.

[0074] The sixth lens L7 has positive optical power, and its object side S10 is convex and its image side S11 is convex.

[0075] The object plane of filter G1 is S12, and the image plane is S13.

[0076] Table 1 shows the relevant parameters of each lens element of the industrial lens 100 in this embodiment.

[0077] Table 1

[0078]

[0079] like Figure 2 , Figure 3 and Figure 4 The figures shown are the distortion curve, MTF diagram, and lateral chromatic aberration curve of the industrial lens 100 provided in the first embodiment of the present invention. Figure 2 It can be seen that the F-Tan (Theta) distortion of the industrial lens 100 is within ±2%, indicating that the distortion of the industrial lens 100 has been well corrected; from Figure 3It can be seen that at a spatial frequency of 180 lp / mm, the MTF value of the industrial lens is above 0.3 across the entire field of view, indicating that the industrial lens 100 has good imaging quality; Figure 4 As can be seen, the transverse chromatic aberration at different wavelengths is controlled within ±3μm, indicating that the transverse chromatic aberration of the industrial lens 100 is well corrected. Therefore, it can be considered that the industrial lens 100 maintains good image quality while achieving good correction of distortion and transverse chromatic aberration.

[0080] Second Embodiment

[0081] like Figure 5 The diagram shown is a structural schematic of the industrial lens 200 provided in the second embodiment. The industrial lens 200 in this embodiment is largely the same as the industrial lens 100 in the first embodiment, except that the relevant parameters of each lens are different from those of the industrial lens 100 in the first embodiment.

[0082] Table 2 shows the relevant parameters of each lens element of the industrial lens 200 in this embodiment.

[0083] Table 2

[0084]

[0085] like Figure 6 , Figure 7 and Figure 8 The figures shown are the distortion curve, MTF diagram, and lateral chromatic aberration curve of the industrial lens 200 provided in the second embodiment of the present invention. Figure 6 It can be seen that the F-Tan (Theta) distortion of the industrial lens 200 is within ±2%, indicating that the distortion of the industrial lens 200 has been well corrected; from Figure 7 It can be seen that at a spatial frequency of 180 lp / mm, the MTF value of the industrial lens is above 0.3 across the entire field of view, indicating that the industrial lens 200 has good imaging quality; Figure 8 As can be seen, the transverse chromatic aberration at different wavelengths is controlled within ±1μm, indicating that the transverse chromatic aberration of the industrial lens 200 is well corrected. Therefore, it can be considered that the industrial lens 200 maintains good image quality while achieving good correction of distortion and transverse chromatic aberration.

[0086] Third Embodiment

[0087] like Figure 9 The diagram shown is a structural schematic of the lens 300 provided in the third embodiment. The lens 300 in this embodiment is largely the same as the lens 100 in the first embodiment, except that the relevant parameters of each lens element are different from those of the lens element in the lens 100 in the first embodiment.

[0088] Table 3 shows the relevant parameters of each lens of the lens 300 in the embodiment.

[0089] Table 3

[0090]

[0091] As shown in Figure 10 , Figure 11 and Figure 12 respectively are the distortion curve, MTF curve and the curve of the axial chromatic aberration of the industrial lens 300 provided by the third embodiment of the present application. As can be seen from Figure 10 , the F-Tan(Theta) distortion of the industrial lens 300 is within ±1%, which shows that the distortion of the industrial lens 300 is well corrected; as can be seen from Figure 11 , the MTF value of the industrial lens in the full field of view is above 0.3 at the spatial frequency of 180 lp / mm, which shows that the industrial lens 300 has good imaging quality; as can be seen from Figure 12 , the axial chromatic aberration at different wavelengths is controlled within ±2μm, which shows that the axial chromatic aberration of the industrial lens 300 is well corrected. Therefore, it can be considered that the industrial lens 300 can maintain good imaging quality while the distortion and the axial chromatic aberration are well corrected.

[0092] Table 4 is the optical characteristics of the lens corresponding to each of the above embodiments, including the field of view FOV, image height IH, effective focal length f, aperture number F / # and total optical length TTL of the industrial lens, and also including the relevant values corresponding to each of the above conditional expressions.

[0093] Table 4

[0094] Conditional expression First embodiment Second embodiment Third embodiment FOV 30° 29° 29.2° IH (mm) 9.2 8.8 9.2 TTL (mm) 29.2 31.3 26.1 f (mm) 16 16 16 F / # 4.2 4.6 4.0 f1 (mm) 25.2 22.7 25.6 f2 (mm) 17.3 18.9 14.2 f3 (mm) -8.8 -7.9 -6.2 f4 (mm) -4.0 -4.7 -8.8 f5 (mm) 5.2 5.4 7.7 f6 (mm) 14.1 15.2 18.4 f min / f max ]]> 1.07 1.07 1.13 CT45 / CT36 0.39 0.32 0.43 CT34 / TTL 0.17 0.20 0.19 DT11 / DT61 1.23 1.25 1.64 |VD4-VD5| 18.466 18.465 20.151 |ND4-ND5| 0.047 0.047 0.082 |Φ21 / R21-Φ22 / R22| / 4 0.12 0.12 0.16 IH / TTL 0.31 0.28 0.35 U / f 1.96-3.58 1.90-3.47 1.68-3.54 (f4+f5+f6) / f 0.95 0.99 1.08

[0095] Compared with the prior art, the industrial lens provided by the present application adopts the combination of 6 spherical lenses with specific optical power and surface shape and 1 voltage-driven zoom lens, which can enable the industrial lens to realize fast focusing and ensure good image quality when used at different object distances, and can well meet the use requirements of application scenarios with relatively high real-time requirements.

[0096] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0097] The above-described embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An industrial lens, six pieces of lens and a piece of voltage-driven zoom lens, characterized in that, In order from the object side to the imaging surface along the optical axis, the industrial lens comprises: a first lens with positive refractive power, the object side surface of the first lens being convex; a second lens with positive refractive power, the object side surface of the second lens being convex, the image side surface of the second lens being concave; a third lens with negative refractive power, the image side surface of the third lens being concave; a voltage-driven zoom lens; a diaphragm; a fourth lens with negative refractive power, the object side surface of the fourth lens being concave, the image side surface of the fourth lens being concave; a fifth lens with positive refractive power, the object side surface of the fifth lens being convex, the image side surface of the fifth lens being convex; a sixth lens with positive refractive power, the object side surface of the sixth lens being convex, the image side surface of the sixth lens being convex; wherein the industrial lens satisfies the following conditional expression: 0.8<|f min / f max |<1.5; wherein f min represents the minimum imaging focal length of the industrial lens, f max represents the maximum imaging focal length of the industrial lens; The voltage-driven zoom lens is energized to change the radius of curvature of the voltage-driven zoom lens.

2. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 0.25 < CT45 / CT36 < 0.5; wherein CT45 represents the distance on the optical axis from the image side surface of the second lens to the object side surface of the third lens, and CT36 represents the distance on the optical axis from the object side surface of the second lens to the image side surface of the third lens.

3. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 0.1 < CT34 / TTL < 0.3; wherein CT34 represents the air gap on the optical axis between the third lens and the fourth lens, and TTL represents the total optical length of the industrial lens.

4. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 1 < DT11 / DT61 < 2; wherein DT11 represents the maximum effective diameter of the object side surface of the first lens, and DT61 represents the maximum effective diameter of the object side surface of the sixth lens.

5. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 20 < |VD4-VD5| < 40; 0.01 < |ND4-ND5| < 0.09; wherein VD4 represents the Abbe number of the fourth lens, VD5 represents the Abbe number of the fifth lens, ND4 represents the refractive index of the fourth lens, and ND5 represents the refractive index of the fifth lens.

6. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: |Φ21 / R21-Φ22 / R22| / 4 > 0.1; wherein Φ21 represents the effective clear aperture of the object side surface of the second lens, R21 represents the radius of curvature of the object side surface of the second lens, Φ22 represents the effective clear aperture of the image side surface of the second lens, and R22 represents the radius of curvature of the image side surface of the second lens.

7. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 0.2 < IH / TTL < 0.4; wherein TTL represents the total optical length of the industrial lens, and IH represents the image height of the industrial lens.

8. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 1.5 < U / f < 3.8; wherein U represents the voltage of the voltage-driven zoom lens at a working object distance, and f represents the effective focal length of the industrial lens.

9. The industrial lens of claim 1, wherein, The industrial lens further satisfies the following conditional expression: 0.8 < (f4+f5+f6) / f < 1.2; Wherein f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, and f represents the effective focal length of the industrial lens.

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