Optical lens for a video displacement meter

Abstract

The application relates to the technical field of optical lenses, in particular to an optical lens for a video displacement meter, which comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the light incidence direction, that is, a six-group seven-piece structure is adopted to meet the use requirements. The central field MTF value of the optical system is greater than 0.2 at 250 lp / mm, the edge field MTF value is greater than 0.2 at 200 lp / mm, the Fno is 2.6, the relative luminance is greater than 50%, the total optical length is less than 15 mm, the use object distance is short, is 20 mm, the horizontal object height is 35 mm, the optical distortion is 15%, and the optical lens is suitable for a 1 / 2.7 chip used by the video displacement meter.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and more particularly to an optical lens for a video displacement meter. Background Technology

[0002] With the increasing demand for digitalization and intelligentization in pumping products, fire trucks, and other applications, hydraulic cylinder displacement detection has become a crucial digital acquisition and fault monitoring point. Especially in the industrial field, for object displacement marker detection, imported wire sensors are currently the primary method. However, these sensors suffer from high prices and high failure rates, becoming a bottleneck in the digital closed-loop control of pumping products. The industry urgently needs digital, stable video displacement gauges. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an optical lens for a video displacement meter.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] An optical lens for a video displacement meter includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light.

[0006] The first lens is a meniscus lens, the second lens is a biconcave lens, the third lens is a biconvex lens, the fourth and fifth lenses form a closely spaced cemented group, the sixth lens is a biconvex lens, and the seventh lens is a meniscus lens.

[0007] The air gap between the first lens and the second lens is 1mm to 2mm, the air gap between the second lens and the third lens is 0mm to 1mm, the air gap between the third lens and the aperture is 0mm to 1mm, the air gap between the aperture and the fourth lens is 0mm to 1mm, the air gap between the fifth lens and the sixth lens is 0mm to 1mm, and the air gap between the sixth lens and the seventh lens is 1mm to 2mm.

[0008] The beneficial effects of this invention are as follows:

[0009] This invention provides an optical lens for a video displacement meter, comprising a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident light direction, i.e., a six-group, seven-element structure, meeting usage requirements. The optical system has a center field-of-view MTF value greater than 0.2 at 250 lp / mm, an edge field-of-view MTF value greater than 0.2 at 200 lp / mm, an Fno of 2.6, a relative illumination greater than 50%, a total optical length less than 15 mm, a short object distance of 20 mm, a horizontal object height of 35 mm, and an optical distortion of 15%, suitable for 1 / 2.7" chips used in video displacement meters. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of an optical lens for a video displacement meter according to the present invention;

[0011] Figure 2 This is an MTF diagram of an optical lens for a video displacement meter according to the present invention;

[0012] Figure 3 This is a distortion diagram of an optical lens for a video displacement meter according to the present invention;

[0013] Label Explanation:

[0014] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens. Detailed Implementation

[0015] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0016] Please refer to Figure 1 The present invention provides an optical lens for a video displacement meter, comprising a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light.

[0017] The first lens is a meniscus lens, the second lens is a biconcave lens, the third lens is a biconvex lens, the fourth and fifth lenses form a closely spaced cemented group, the sixth lens is a biconvex lens, and the seventh lens is a meniscus lens.

[0018] The air gap between the first lens and the second lens is 1mm to 2mm, the air gap between the second lens and the third lens is 0mm to 1mm, the air gap between the third lens and the aperture is 0mm to 1mm, the air gap between the aperture and the fourth lens is 0mm to 1mm, the air gap between the fifth lens and the sixth lens is 0mm to 1mm, and the air gap between the sixth lens and the seventh lens is 1mm to 2mm.

[0019] As can be seen from the above description, the beneficial effects of the present invention are as follows:

[0020] This invention provides an optical lens for a video displacement meter, comprising a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident light direction, i.e., a six-group, seven-element structure, meeting usage requirements. The optical system has a center field-of-view MTF value greater than 0.2 at 250 lp / mm, an edge field-of-view MTF value greater than 0.2 at 200 lp / mm, an Fno of 2.6, a relative illumination greater than 50%, a total optical length less than 15 mm, a short object distance (20 mm), a horizontal object height of 35 mm, and an optical distortion of 15%, suitable for 1 / 2.7" chips used in video displacement meters.

[0021] Furthermore, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens further satisfy the following optical conditions:

[0022] 1.4 <n1<1.5,70<v1<80;

[0023] 1.5 <n2<1.6,40<v2<50;

[0024] 2.0 <n3<2.1,20<v3<30;

[0025] 1.7 <n4<1.8,20<v4<30;

[0026] 1.5 <n5<1.6,60<v5<70;

[0027] 1.5 <n6<1.6,60<v6<70;

[0028] 1.6 <n7<1.7,30<v7<40;

[0029] Where n1-n7 are the refractive indices of the first lens to the seventh lens, respectively, and v1-v7 are the Abbe coefficients of the first lens to the seventh lens, respectively.

[0030] Furthermore, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens further satisfy the following optical conditions:

[0031] The radius of curvature of the side of the first lens away from the second lens is 4 to 6 mm, and the radius of curvature of the side of the first lens closer to the second lens is 2 to 3 mm.

[0032] The radius of curvature of the side of the second lens furthest from the third lens ranges from -30 to -20 mm, and the radius of curvature of the side of the second lens closest to the third lens ranges from 3 to 10 mm.

[0033] The radius of curvature of the side of the third lens away from the fourth lens is in the range of 0 to 10 mm, and the radius of curvature of the side of the third lens close to the fourth lens is in the range of -10 to -5 mm.

[0034] The radius of curvature of the side of the fourth lens away from the fifth lens is in the range of -5 to -4 mm, and the radius of curvature of the side of the fourth lens closer to the fifth lens is in the range of 2 to 3 mm.

[0035] The radius of curvature of the side of the fifth lens away from the sixth lens is in the range of 2 to 3 mm, and the radius of curvature of the side of the fifth lens close to the sixth lens is in the range of -5 to -3 mm.

[0036] The radius of curvature of the side of the sixth lens away from the seventh lens is 5 to 10 mm, and the radius of curvature of the side of the sixth lens close to the seventh lens is -10 to -5 mm.

[0037] The radius of curvature of the side of the seventh lens closest to the sixth lens ranges from -7 to -3 mm, and the radius of curvature of the side of the seventh lens furthest from the sixth lens ranges from -10 to 0 mm.

[0038] Furthermore, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens further satisfy the following optical conditions:

[0039] The center thickness of the first lens ranges from 0 mm to 1 mm;

[0040] The center thickness of the second lens ranges from 0 mm to 1 mm;

[0041] The center thickness of the third lens ranges from 1 mm to 2 mm;

[0042] The center thickness of the fourth lens ranges from 1 mm to 2 mm;

[0043] The center thickness of the fifth lens ranges from 2mm to 3mm;

[0044] The central thickness of the sixth lens ranges from 1 mm to 2 mm;

[0045] The central thickness of the seventh lens ranges from 0 mm to 1 mm.

[0046] Furthermore, the combined focal length of the first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, the sixth lens, and the seventh lens is 4 mm, and the overall optical length of the optical lens is less than 15 mm.

[0047] Please refer to Figures 1 to 3 , Example 1 of the present invention is as follows:

[0048] As Figure 1 , an optical lens for a video displacement meter provided by the present invention includes a first lens 1, a second lens 2, a third lens 3, an aperture stop, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a seventh lens 7 arranged in sequence along the light incident direction;

[0049] The first lens 1 is a meniscus lens, the second lens 2 is a biconcave lens, the third lens 3 is a biconvex lens, the fourth lens 4 and the fifth lens 5 form a closely adhered cemented group, the sixth lens 6 is a biconvex lens, and the seventh lens 7 is a meniscus lens;

[0050] The air gap between the first lens 1 and the second lens 2 ranges from 1 mm to 2 mm, the air gap between the second lens 2 and the third lens 3 ranges from 0 mm to 1 mm, the air gap between the third lens 3 and the aperture stop ranges from 0 mm to 1 mm, the air gap between the aperture stop and the fourth lens 4 ranges from 0 mm to 1 mm, the air gap between the fifth lens 5 and the sixth lens 6 ranges from 0 mm to 1 mm, and the air gap between the sixth lens 6 and the seventh lens 7 ranges from 1 mm to 2 mm.

[0051] The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens further satisfy the following optical conditions:

[0052] 1.4 < n1 < 1.5, 70 < v1 < 80; the radius of curvature of the side surface (S1 surface) of the first lens away from the second lens ranges from 4 to 6 mm, the radius of curvature of the side surface (S2 surface) of the first lens close to the second lens ranges from 2 to 3 mm; the central thickness of the first lens ranges from 0 mm to 1 mm;

[0053] In this embodiment, n1 is taken as 1.49, v1 is taken as 70.4, the radius of curvature of the S1 surface is 4.3, and the radius of curvature of the S2 surface is 2.19.

[0054] 1.5 < n2 < 1.6, 40 < v2 < 50; The radius of curvature range of the side (S3 surface) of the second lens away from the third lens is -30 to -20 mm, and the radius of curvature range of the side (S4 surface) of the second lens close to the third lens is 3 to 10 mm; The central thickness range of the second lens is 0 mm to 1 mm;

[0055] In this embodiment, the value of n2 is 1.57, the value of v1 is 42.8, the radius of curvature of the S3 surface is -21.73 mm, and the radius of curvature of the S4 surface is 3.27 mm.

[0056] 2.0 < n3 < 2.1, 20 < v3 < 30; The radius of curvature range of the side (S5 surface) of the third lens away from the fourth lens is 0 to 10 mm, and the radius of curvature range of the side (S6 surface) of the third lens close to the fourth lens is -10 to -5 mm; The central thickness range of the third lens is 1 mm to 2 mm;

[0057] In this embodiment, the value of n3 is 2.00, the value of v3 is 29.1, the radius of curvature of the S5 surface is 4.3 mm, and the radius of curvature of the S6 surface is -7.65 mm.

[0058] 1.7 < n4 < 1.8, 20 < v4 < 30; The radius of curvature range of the side (S8 surface) of the fourth lens away from the fifth lens is -5 to -4 mm, and the radius of curvature range of the side (S9 surface) of the fourth lens close to the fifth lens is 2 to 3 mm; The central thickness range of the fourth lens is 1 mm to 2 mm;

[0059] In this embodiment, the value of n4 is 1.72, the value of v4 is 29.5, the radius of curvature of the S8 surface is -4.05 mm, and the radius of curvature of the S9 surface is 3 mm.

[0060] 1.5 < n5 < 1.6, 60 < v5 < 70; The radius of curvature range of the side (S9 surface) of the fifth lens away from the sixth lens is 2 to 3 mm, and the radius of curvature range of the side (S10 surface) of the fifth lens close to the sixth lens is -5 to -3 mm; The central thickness range of the fifth lens is 2 mm to 3 mm;

[0061] In this embodiment, the value of n5 is 1.59, the value of v5 is 68.3, the radius of curvature of the S9 surface is 3 mm, and the radius of curvature of the S10 surface is -3.57 mm.

[0062] 1.5 < n6 < 1.6, 60 < v6 < 70; The radius of curvature of the side of the sixth lens away from the seventh lens (S11 surface) ranges from 5 to 10 mm, and the radius of curvature of the side of the sixth lens close to the seventh lens (S12 surface) ranges from -10 to -5 mm; The central thickness of the sixth lens ranges from 1 mm to 2 mm;

[0063] In this embodiment, n6 is taken as 1.59, v6 is taken as 68.3, the radius of curvature of the S11 surface is 6.94 mm, and the radius of curvature of the S12 surface is -6.94 mm.

[0064] 1.6 < n7 < 1.7, 30 < v7 < 40; The radius of curvature of the side of the seventh lens close to the sixth lens (S13 surface) ranges from -7 to -3 mm, and the radius of curvature of the side of the seventh lens away from the sixth lens (S14 surface) ranges from -10 to 0 mm. The central thickness of the seventh lens ranges from 0 mm to 1 mm.

[0065] In this embodiment, n7 is taken as 1.65, v7 is taken as 33.8, the radius of curvature of the S13 surface is -3.9 mm, and the radius of curvature of the S14 surface is -7.1 mm.

[0066] Among them, n1 - n7 are the refractive indices of the first lens - the seventh lens in sequence, and v1 - v7 are the Abbe numbers of the first lens - the seventh lens in sequence.

[0067] The combined focal length of the first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, the sixth lens, and the seventh lens is 4 mm, and the overall optical length of the optical lens is less than 15 mm.

[0068] In this implementation scheme, the overall optical length is 15 mm, Fno 2.6, the maximum horizontal object height is 35 mm, the relative illumination is 50%, and the distortion is 15%.

[0069] The specific implementation data is as shown in Table 1 below:

[0070]

[0071] Table 1

[0072] Such as Figures 2 to 3 , The present invention has the following advantages:

[0073] This invention provides an optical lens for a video displacement meter, employing a six-group, seven-element structure. The center field-of-view MTF value is 0.4 at 250 lp / mm, the peripheral field-of-view MTF value is 0.2 at 200 lp / mm, and the distortion is 15%. It achieves image clarity without blurring under conditions ranging from -30° to 70°. It achieves a lens centering factor >0.1, an angle of attack <60°, and a thickness >0.6mm with a short total optical length, making it easy to manufacture.

[0074] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An optical lens for a video displacement meter, characterized in that, The optical lens adopts a six-group, seven-element structure, and includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light. The first lens is a meniscus lens, the second lens is a biconcave lens, the third lens is a biconvex lens, the fourth and fifth lenses form a closely spaced cemented group, the sixth lens is a biconvex lens, and the seventh lens is a meniscus lens. The air gap between the first lens and the second lens is 1mm to 2mm, the air gap between the second lens and the third lens is 0mm to 1mm, the air gap between the third lens and the aperture is 0mm to 1mm, the air gap between the aperture and the fourth lens is 0mm to 1mm, the air gap between the fifth lens and the sixth lens is 0mm to 1mm, and the air gap between the sixth lens and the seventh lens is 1mm to 2mm.

2. The optical lens for a video displacement meter according to claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens further satisfy the following optical conditions: 1.4 <n1<1.5,70<v1<80; 1.5 <n2<1.6,40<v2<50; 2.0 <n3<2.1,20<v3<30; 1.7 <n4<1.8,20<v4<30; 1.5 <n5<1.6,60<v5<70; 1.5 <n6<1.6,60<v6<70; 1.6 <n7<1.7,30<v7<40; Where n1~n7 are the refractive indices of the first lens to the seventh lens, respectively, and v1~v7 are the Abbe coefficients of the first lens to the seventh lens, respectively.

3. An optical lens for a video displacement meter according to claim 2, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens further satisfy the following optical conditions: The radius of curvature of the side of the first lens away from the second lens is 4 to 6 mm, and the radius of curvature of the side of the first lens closer to the second lens is 2 to 3 mm. The radius of curvature of the side of the second lens furthest from the third lens ranges from -30 to -20 mm, and the radius of curvature of the side of the second lens closest to the third lens ranges from 3 to 10 mm. The radius of curvature of the side of the third lens away from the fourth lens is in the range of 0 to 10 mm, and the radius of curvature of the side of the third lens close to the fourth lens is in the range of -10 to -5 mm. The radius of curvature of the side of the fourth lens away from the fifth lens is in the range of -5 to -4 mm, and the radius of curvature of the side of the fourth lens closer to the fifth lens is in the range of 2 to 3 mm. The radius of curvature of the side of the fifth lens away from the sixth lens is in the range of 2 to 3 mm, and the radius of curvature of the side of the fifth lens close to the sixth lens is in the range of -5 to -3 mm. The radius of curvature of the side of the sixth lens away from the seventh lens is 5 to 10 mm, and the radius of curvature of the side of the sixth lens close to the seventh lens is -10 to -5 mm. The radius of curvature of the side of the seventh lens closest to the sixth lens ranges from -7 to -3 mm, and the radius of curvature of the side of the seventh lens furthest from the sixth lens ranges from -7.1 mm.

4. An optical lens for a video displacement meter according to claim 2, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens further satisfy the following optical conditions: The center thickness of the first lens ranges from 0 mm to 1 mm; The center thickness of the second lens ranges from 0 mm to 1 mm; The center thickness of the third lens ranges from 1 mm to 2 mm; The center thickness of the fourth lens ranges from 1 mm to 2 mm; The center thickness of the fifth lens ranges from 2mm to 3mm; The center thickness of the sixth lens ranges from 1 mm to 2 mm; The center thickness of the seventh lens ranges from 0 mm to 1 mm.

5. An optical lens for a video displacement meter according to claim 1, characterized in that, The combined focal length of the first lens, second lens, third lens, aperture, fourth lens, fifth lens, sixth lens, and seventh lens is 4mm, and the total optical length of the optical lens is less than 15mm.

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