Near-infrared floating focusing machine vision lens and working method thereof

Abstract

The present application relates to a kind of near-infrared floating focusing machine vision lens and its working method, belong to imaging optical system design technical field.The lens includes first lens G1, second lens G2, third lens G3, fourth lens G4, fifth lens G5, diaphragm STOP, sixth lens G6, seventh lens G7, eighth lens G8, ninth lens G9, tenth lens G10 and eleventh lens G11 and protective lens are sequentially arranged from object side to image side along optical axis.The present application uses eleven global surface lenses, adopts floating focusing, moves by controlling the diaphragm front group to cooperate under different working distance work.Can be applicable to chip size 1'', with large aperture, meet the requirements of high illumination, low chromatic aberration, small distortion and other requirements of semiconductor detection lens in machine vision detection field.

Description

Technical Field

[0001] This invention belongs to the field of imaging optical system design technology, specifically relating to a near-infrared floating focusing machine vision lens and its working method. Background Technology

[0002] The intelligent inspection of photovoltaic cells based on machine vision is developing rapidly. It monitors cell defects in real time by detecting the infrared light emitted by the cells. For such scenarios, the lens needs a large aperture to ensure sufficient light intake and focus at different object distances. However, the quality of related lenses on the market varies greatly, and their working distances and application wavelength ranges cannot meet the requirements well. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a near-infrared floating focusing machine vision lens and its working method, which can achieve the characteristics of large aperture, large target surface, small distortion, and long working distance, and is sensitive to the fluorescence band emitted by the detection of battery cells, with good chromatic aberration and spherical aberration correction.

[0004] To achieve the above objectives, the technical solution of the present invention is: a near-infrared floating focusing machine vision lens, comprising a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, an aperture stop STOP, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, a tenth lens G10, and an eleventh lens G11 arranged sequentially along the optical axis from the object side to the image side.

[0005] In one embodiment of the present invention, the first lens G1 is a convex-plano positive lens, the second lens G2 is a meniscus negative lens, the third lens G3 is a meniscus negative lens, the fourth lens G4 is a biconcave negative lens, the fifth lens G5 is a biconvex positive lens, the sixth lens G6 is a meniscus positive lens, the seventh lens G7 is a biconvex positive lens, the eighth lens G8 is a biconcave negative lens, the ninth lens G9 is a biconvex positive lens, the tenth lens G10 is a meniscus positive lens, and the eleventh lens G11 is a convex-plano negative lens.

[0006] In one embodiment of the present invention, the seventh lens G7 and the eighth lens G8 are cemented together to form a first cemented lens; the tenth lens G10 and the eleventh lens G11 are cemented together to form a second cemented lens.

[0007] In one embodiment of the present invention, the air gap between the first lens G1 and the second lens G2 is 0.15 mm, the air gap between the second lens G2 and the third lens G3 is 2.51 mm, the air gap between the third lens G3 and the fourth lens G4 is adjustable, the air gap between the fourth lens G4 and the fifth lens G5 is 5.17 mm, the air gap between the fifth lens G5 and the stop is adjustable, the air gap between the stop and the sixth lens G6 is 7.93 mm, the air gap between the sixth lens G6 and the seventh lens G7 is 0.15 mm, the air gap between the eighth lens G8 and the ninth lens G9 is 7.13 mm, and the air gap between the ninth lens G9 and the tenth lens G10 is 0.15 mm.

[0008] In one embodiment of the present invention, the first lens G1, the second lens G2 and the third lens G3 constitute a first lens group L1, the fourth lens G4 and the fifth lens G5 constitute a second lens group L2, and the sixth lens G6, the seventh lens G7, the eighth lens G8, the ninth lens G9, the tenth lens G10 and the eleventh lens G11 constitute a third lens group L3.

[0009] In one embodiment of the present invention, the refractive index and dispersion coefficient from the first lens G1 to the eleventh lens G11 satisfy the following:

[0010] 1.60≤n1≤1.80; 50.0≤v1≤65.0;

[0011] 1.70≤n²≤1.90; 20.0≤v²≤35.0;

[0012] 1.75≤n3≤1.95; 20.0≤v3≤35.0;

[0013] 1.50≤n4≤1.70; 35.0≤v4≤50.0;

[0014] 1.70≤n5≤1.90; 30.0≤v5≤50.0;

[0015] 1.60≤n6≤1.80; 45.0≤v6≤60.0;

[0016] 1.50≤n7≤1.70; 60.0≤v7≤75.0;

[0017] 1.60≤n8≤1.80; 25.0≤v8≤40.0;

[0018] 1.60≤n9≤1.80; 45.0≤v9≤60.0;

[0019] 1.80≤n10≤2.00;20.0≤v10≤35.0;

[0020] 1.75≤n11≤1.95; 30.0≤v11≤45.0;

[0021] Wherein, nd1, nd2, nd3, nd4, nd5, nd6, nd7, nd8, nd9, nd10 and nd11 are the refractive indices of the first lens G1 to the eleventh lens G11, respectively; vd1, vd2, vd3, vd4, vd5, vd6, vd7, vd8, vd9, vd10 and vd11 are the dispersion coefficients of the first lens G1 to the eleventh lens G11, respectively.

[0022] In one embodiment of the present invention, the first lens group L1, the second lens group L2 and the third lens group L3 are all spherical glass lenses.

[0023] In one embodiment of the present invention, a photosensitive chip is provided on the image side, and a filter group and / or protective glass are provided between the eleventh lens G11 and the photosensitive chip.

[0024] In one embodiment of the present invention, the design spectrum of the near-infrared floating focus machine vision lens is 900nm-1500nm wavelength of near-infrared light, with a maximum F-number of 1.6 at full aperture, using a large aperture to achieve a large amount of light intake, an image size Φ = 16mm, and an applicable image sensor size of 1.

[0025] The present invention also provides a working method based on the lens described above, which adopts a floating focusing method to achieve a wide working distance. That is, by moving the first lens group L1 and the second lens group L2 back and forth, the lens can work at different working distances to ensure the imaging quality at different object distances.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] 1. It uses two sets of cemented lens groups to achromatic, and adopts a floating focusing structure to achieve a clear image from 300mm to infinity. The positive and negative optical powers are matched, and the structure is reasonable.

[0028] 2. The design spectrum is 900-1500nm near-infrared light. The maximum F number is 1.6 when the aperture is fully open. The large aperture achieves a large amount of light intake. The image size is Φ=16mm, which can be used with a chip size of 1” to achieve a large target surface. It performs better under low light conditions. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a near-infrared floating focusing machine vision lens structure according to the present invention.

[0030] Figure 2This is the MTF plot of Embodiment 1 of the present invention at an object distance of 600 mm;

[0031] Figure 3 This is the vertical chromatic difference image of Embodiment 1 of the present invention at an object distance of 600mm;

[0032] Figure 4 This is an optical distortion curve of Embodiment 1 of the present invention at an object distance of 600 mm.

[0033] In the diagram, G1 is the first lens; G2 is the second lens; G3 is the third lens; G4 is the fourth lens; G5 is the fifth lens; G6 is the sixth lens; G7 is the seventh lens; G8 is the eighth lens; G9 is the ninth lens; G10 is the tenth lens; G11 is the eleventh lens; H1 is the filter group / protective glass; STOP is the variable aperture; and IMA is the imaging plane. Detailed Implementation

[0034] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] Reference Figure 1 As shown, this is a near-infrared floating focusing machine vision lens according to an embodiment of the present invention. The optical system of the lens includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, an aperture stop, a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, a tenth lens G10, an eleventh lens G11 and a protective lens, which are arranged sequentially from front to back along the incident light path.

[0037] In this embodiment of the invention, the first lens G1 is a convex-plano positive lens, the second lens G2 is a meniscus negative lens, the third lens G3 is a meniscus negative lens, the fourth lens G4 is a biconcave negative lens, the fifth lens G5 is a biconvex positive lens, the sixth lens G6 is a meniscus positive lens, the seventh lens G7 is a biconvex positive lens, the eighth lens G8 is a biconcave negative lens, the ninth lens G9 is a biconvex positive lens, the tenth lens G10 is a meniscus positive lens, and the eleventh lens G11 is a convex-plano negative lens.

[0038] In this embodiment of the invention, the seventh lens G7 and the eighth lens G8 are cemented together to form a first cemented lens, and the tenth lens G10 and the eleventh lens G11 are cemented together to form a second cemented lens.

[0039] In this embodiment of the invention, the air gap between the first lens G1 and the second lens G2 is 0.15 mm, the air gap between the second lens G2 and the third lens G3 is 2.51 mm, the air gap between the third lens G3 and the fourth lens G4 is adjustable, the air gap between the fourth lens G4 and the fifth lens G5 is 5.17 mm, the air gap between the fifth lens G5 and the stop is adjustable, the air gap between the stop and the sixth lens G6 is 7.93 mm, the air gap between the sixth lens G6 and the seventh lens G7 is 0.15 mm, the air gap between the eighth lens G8 and the ninth lens G9 is 7.13 mm, and the air gap between the ninth lens G9 and the tenth lens G10 is 0.15 mm.

[0040] In this embodiment of the invention, the first lens G1, the second lens G2 and the third lens G3 form the first lens group L1, the fourth lens G4 and the fifth lens G5 form the second lens group L2, and the sixth lens G6, the seventh lens G7, the eighth lens G8, the ninth lens G9, the tenth lens G10 and the eleventh lens G11 form the third lens group L3.

[0041] In this embodiment of the invention, the refractive index and dispersion coefficient of the lens from the first lens to the eleventh lens satisfy the following:

[0042] 1.60≤n1≤1.80; 50.0≤v1≤65.0;

[0043] 1.70≤n²≤1.90; 20.0≤v²≤35.0;

[0044] 1.75≤n3≤1.95; 20.0≤v3≤35.0;

[0045] 1.50≤n4≤1.70; 35.0≤v4≤50.0;

[0046] 1.70≤n5≤1.90; 30.0≤v5≤50.0;

[0047] 1.60≤n6≤1.80; 45.0≤v6≤60.0;

[0048] 1.50≤n7≤1.70; 60.0≤v7≤75.0;

[0049] 1.60≤n8≤1.80; 25.0≤v8≤40.0;

[0050] 1.60≤n9≤1.80; 45.0≤v9≤60.0;

[0051] 1.80≤n10≤2.00;20.0≤v10≤35.0;

[0052] 1.75≤n11≤1.95; 30.0≤v11≤45.0;

[0053] Wherein, nd1, nd2, nd3, nd4, nd5, nd6, nd7, nd8, nd9, nd10 and nd11 are the refractive indices of the first to eleventh lenses, respectively; vd1, vd2, vd3, vd4, vd5, vd6, vd7, vd8, vd9, vd10 and vd11 are the dispersion coefficients of the first to eleventh lenses, respectively.

[0054] In this embodiment of the invention, the first lens group L1, the second lens group L2, and the third lens group L3 are all spherical glass lenses.

[0055] In this embodiment of the invention, a photosensitive chip is provided on the image side, and a filter group and / or protective glass are provided between the eleventh lens and the photosensitive chip.

[0056] To illustrate with a specific example, the radii of curvature, thickness, refractive index, and dispersion coefficient of the glass used in this optical system are as follows:

[0057] Table 1. Detailed optical data of a near-infrared floating focus machine vision lens:

[0058]

[0059] In this specific embodiment, the focusing movement distance at different working distances must meet the parameter requirements shown in Table 2.

[0060] Table 2 shows the focusing movement distance parameters under different working distances.

[0061]

[0062] In this specific embodiment, the lens achieves the following optical specifications:

[0063] (1) The working object distance of the lens ranges from 300mm to infinity;

[0064] (2) The maximum image area of ​​the lens is φ16mm, which can be adapted to a chip with a 1-inch target surface;

[0065] (3) The focal length of the lens is 35mm;

[0066] (4) A lens with an MTF greater than 0.2 at 120 lp / mm line pairs can provide a clear image;

[0067] (5) The lens has an F-number of 1.6 and a relative illumination greater than 80% within the working distance range;

[0068] (6) Distortion at all object distances is less than 1%;

[0069] (7) CRA less than 3°.

[0070] See Figure 1 As can be seen from Tables 1 and 2, this specific embodiment ensures imaging quality at different object distances by moving the first lens group and the second lens group back and forth.

[0071] In a specific embodiment, the optical imaging lens has a focal length f = 35mm; a maximum aperture FNO = 1.6; an image plane size Φ = 16mm; and a distance TTL between the object side 1 of the first lens and the imaging plane 24 on the optical axis = 143.94mm. It employs front and rear floating focusing, controlling the movement of the first and second lens groups to coordinate the lens's operation at different working distances, achieving distortion of less than 1% across all object distances. It is compatible with a 1-inch image sensor (effective target area Φ = 16mm), exhibits good imaging quality in the near-infrared band, and demonstrates good chromatic and spherical aberration correction.

[0072] Figure 2 The figure shows the MTF curve of this specific embodiment at an object distance of 600mm. The horizontal axis is the spatial frequency of the MTF curve, in lp / mm, and the vertical axis is the value of the modulation transfer function, which represents the degree of image reproduction. This figure shows that the MTF of this lens is >0.2 at 120lp / mm.

[0073] Figure 3 The figure shows the optical distortion curve of this specific embodiment at an object distance of 600mm. The horizontal axis represents the distortion percentage, and the vertical axis represents the normalized field of view height. This figure indicates that the distortion of this lens is <1%.

[0074] This solution achieves an optical system with a large aperture, large target surface, low chromatic aberration, and low distortion optical lens with a focal length of 35mm through the above structure. The maximum F number at the image side is 1.6, the maximum resolution can reach 120lp / mm, and the maximum optical distortion across the entire field of view is less than 1%. It adopts a floating focusing method to achieve a wide working distance and can be matched with various manufacturers' testing equipment.

[0075] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A near-infrared floating focusing machine vision lens, characterized in that, The system comprises a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, an aperture stop (STOP), a sixth lens G6, a seventh lens G7, an eighth lens G8, a ninth lens G9, a tenth lens G10, and an eleventh lens G11, arranged sequentially along the optical axis from the object side to the image side. The first lens G1 is a convex plano-positive lens; the second lens G2 is a meniscus negative lens; the third lens G3 is a meniscus negative lens; the fourth lens G4 is a biconcave negative lens; the fifth lens G5 is a biconvex positive lens; the sixth lens G6 is a meniscus positive lens; the seventh lens G7 is a biconvex positive lens; the eighth lens G8 is a biconcave negative lens; the ninth lens G9 is a biconvex positive lens; the tenth lens G10 is a meniscus positive lens; and the eleventh lens G11 is a convex plano-positive lens. The refractive index and dispersion coefficient of the first lens G1 to the eleventh lens G11 satisfy the following conditions: 1.60≤n1≤1.80; 50.0≤v1≤65.0; 1.70≤n²≤1.90; 20.0≤v²≤35.0; 1.75≤n3≤1.95; 20.0≤v3≤35.0; 1.50≤n4≤1.70; 35.0≤v4≤50.0; 1.70≤n5≤1.90; 30.0≤v5≤50.0; 1.60≤n6≤1.80; 45.0≤v6≤60.0; 1.50≤n7≤1.70; 60.0≤v7≤75.0; 1.60≤n8≤1.80; 25.0≤v8≤40.0; 1.60≤n9≤1.80; 45.0≤v9≤60.0; 1.80≤n10≤2.00;20.0≤v10≤35.0; 1.75≤n11≤1.95; 30.0≤v11≤45.0; Wherein, nd1, nd2, nd3, nd4, nd5, nd6, nd7, nd8, nd9, nd10 and nd11 are the refractive indices of the first lens G1 to the eleventh lens G11, respectively; vd1, vd2, vd3, vd4, vd5, vd6, vd7, vd8, vd9, vd10 and vd11 are the dispersion coefficients of the first lens G1 to the eleventh lens G11, respectively.

2. The near-infrared floating focusing machine vision lens according to claim 1, characterized in that, The air gap between the first lens G1 and the second lens G2 is 0.15 mm, the air gap between the second lens G2 and the third lens G3 is 2.51 mm, the air gap between the third lens G3 and the fourth lens G4 is adjustable, the air gap between the fourth lens G4 and the fifth lens G5 is 5.17 mm, the air gap between the fifth lens G5 and the stop is adjustable, the air gap between the stop and the sixth lens G6 is 7.93 mm, the air gap between the sixth lens G6 and the seventh lens G7 is 0.15 mm, the air gap between the eighth lens G8 and the ninth lens G9 is 7.13 mm, and the air gap between the ninth lens G9 and the tenth lens G10 is 0.15 mm.

3. A near-infrared floating focusing machine vision lens according to claim 1, characterized in that, The first lens G1, the second lens G2, and the third lens G3 form the first lens group L1; the fourth lens G4 and the fifth lens G5 form the second lens group L2; and the sixth lens G6, the seventh lens G7, the eighth lens G8, the ninth lens G9, the tenth lens G10, and the eleventh lens G11 form the third lens group L3.

4. A near-infrared floating focusing machine vision lens according to claim 3, characterized in that, The first lens group L1, the second lens group L2, and the third lens group L3 are all spherical glass lenses.

5. A near-infrared floating focusing machine vision lens according to claim 1, characterized in that, A photosensitive chip is provided on the image side, and a filter group and / or protective glass are provided between the eleventh lens G11 and the photosensitive chip.

6. A near-infrared floating focusing machine vision lens according to claim 5, characterized in that, The design spectrum of the near-infrared floating focus machine vision lens is 900nm-1500nm wavelength near-infrared light. The maximum F number is 1.6 when the aperture is wide open, and a large aperture is used to achieve a large amount of light intake. The image plane size is Φ=16mm, and the applicable image sensor size is 1 inch.

7. A method for operating a lens based on claim 3 or 4, characterized in that, A floating focus method is adopted to achieve a wide working distance. That is, by moving the first lens group L1 and the second lens group L2 back and forth, the lens can work at different working distances to ensure the imaging quality at different object distances.

Images