Prime lens and machine vision equipment

Abstract

The utility model discloses a prime lens and machine vision equipment. The prime lens comprises a first lens with negative 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 focal power, a sixth lens with focal power and a seventh lens with positive focal power which are sequentially arranged from the object space to the image space. An eighth lens with positive focal power, a ninth lens with focal power and a tenth lens with focal power; wherein the fifth lens and the sixth lens are glued to form a first glued lens with negative focal power, and the ninth lens and the tenth lens are glued to form a second glued lens with positive focal power. The focal length of the prime lens is 16mm, the field angle is 39.4 degrees, the TV distortion of the lens is less than 0.04%, the optical distortion is less than 0.4%, and the lens can work stably at 10-50 DEG C.

Description

Technical Field

[0001] The utility model relates to the technical field of optics, in particular to a fixed-focus lens and machine vision equipment. Background Art

[0002] Machine vision lenses are widely used in industries such as warehousing and logistics, and industrial automation. Industrial automation places high demands on machine vision lenses for image clarity, reliability, distortion reduction, and field of view. Traditional machine vision lenses suffer from low resolution and significant distortion. Utility Model Content

[0003] The utility model provides a fixed-focus lens and a machine vision device. The fixed-focus lens adopts a spherical glass lens and has the characteristics of large aperture, small distortion, high relative illumination, uniform imaging, and low cost. It can match a sensor chip with a maximum target surface of 2 / 3".

[0004] To achieve the above-mentioned object, the present invention provides a fixed-focus lens, comprising a first lens having negative optical power, a second lens having positive optical power, a third lens having positive optical power, a fourth lens having negative optical power, a fifth lens having optical power, a sixth lens having optical power, a seventh lens having positive optical power, an eighth lens having positive optical power, a ninth lens having optical power, and a tenth lens having optical power, which are arranged in sequence from the object side to the image side.

[0005] The fifth lens and the sixth lens are cemented together to form a first cemented lens with negative optical power, and the ninth lens and the tenth lens are cemented together to form a second cemented lens with positive optical power.

[0006] Optionally, the object side surface of the first lens is concave, and the image side surface is concave; the object side surface of the second lens is convex, and the image side surface is convex; the object side surface of the third lens is convex, and the image side surface is convex; the object side surface of the fourth lens is convex, and the image side surface is concave; the object side surface of the fifth lens is concave, and the image side surface is concave; the object side surface of the sixth lens is convex, and the image side surface is convex; the object side surface of the seventh lens is convex, and the image side surface is convex; the object side surface of the eighth lens is convex, and the image side surface is convex; the object side surface of the ninth lens is convex, and the image side surface is concave; and the object side surface of the tenth lens is convex, and the image side surface is convex.

[0007] Optionally, the object side surface of the first lens is convex, and the image side surface is concave; the object side surface of the second lens is concave, and the image side surface is convex; the object side surface of the third lens is convex, and the image side surface is convex; the object side surface of the fourth lens is convex, and the image side surface is concave; the object side surface of the fifth lens is concave, and the image side surface is concave; the object side surface of the sixth lens is convex, and the image side surface is convex; the object side surface of the seventh lens is convex, and the image side surface is convex; the object side surface of the eighth lens is convex, and the image side surface is convex; the object side surface of the ninth lens is convex, and the image side surface is concave; the object side surface of the tenth lens is convex, and the image side surface is concave.

[0008] Optionally, the object side surface of the first lens is concave, and the image side surface is concave; the object side surface of the second lens is convex, and the image side surface is convex; the object side surface of the third lens is convex, and the image side surface is concave; the object side surface of the fourth lens is convex, and the image side surface is concave; the object side surface of the fifth lens is concave, and the image side surface is concave; the object side surface of the sixth lens is convex, and the image side surface is convex; the object side surface of the seventh lens is convex, and the image side surface is convex; the object side surface of the eighth lens is convex, and the image side surface is convex; the object side surface of the ninth lens is convex, and the image side surface is concave; and the object side surface of the tenth lens is convex, and the image side surface is concave.

[0009] Optionally, the focal powers of the first to tenth lenses and the focal power of the fixed-focus lens satisfy the following relationship:

[0010] in, is the optical focal length.

[0011] Optionally, a curvature radius R41 on the object side of the fourth lens, a curvature radius R42 on the image side, and an axial thickness D4 of the fourth lens satisfy the following relationship:

[0012] 0.02≤||R41-R42|-D4|≤1.55.

[0013] Optionally, the curvature radius R51 on the object plane side of the first cemented lens, the curvature radius R62 on the image plane side, and the axial thickness D56 of the first cemented lens satisfy the following relationship:

[0014] 0.05≤||R51-R62|-D56|≤1.55.

[0015] Optionally, the refractive indices of the first lens to the tenth lens satisfy the following relationship:

[0016] 1.75≤n1≤1.85;1.60≤n2≤1.65;1.80≤n3≤1.85;1.60≤n4≤1.65;

[0017] 1.80≤n5≤1.85;1.60≤n6≤1.65;1.55≤n7≤1.60;1.60≤n8≤1.65;

[0018] 1.60≤n9≤1.70; 1.45≤n8≤1.55, where n is the refractive index.

[0019] Optionally, the Abbe numbers of the first lens to the tenth lens satisfy the following relationship:

[0020] 25.5≤v1≤30.0;55.0≤v2≤57.0;37.0≤v3≤37.5;58.0≤v4≤60.5;

[0021] 25.0≤v5≤25.5;63.0≤v6≤63.5;68.0≤v7≤69.0;55.0≤v8≤57.0;

[0022] 56.5≤v9≤58.5; 80.5≤v8≤82.0, where v is the Abbe number.

[0023] To achieve the above-mentioned purpose, the present invention further proposes a machine vision device, comprising the fixed-focus lens proposed in any embodiment of the present invention, wherein the fixed-focus lens is applied to a machine vision lens.

[0024] The fixed-focus lens and machine vision equipment proposed in this utility model include a first lens with negative optical power, a second lens with positive optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with optical power, a sixth lens with optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with optical power, and a tenth lens with optical power, arranged sequentially from the object side to the image side. The fifth and sixth lenses are cemented together to form a first cemented lens with negative optical power, and the ninth and tenth lenses are cemented together to form a second cemented lens with positive optical power. The fixed-focus lens has a focal length of 16mm and a field of view of 39.4°. The lens exhibits TV distortion of less than 0.04% and optical distortion of less than 0.4%, and can operate stably at temperatures between 10°C and 50°C.

[0025] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 1 is a schematic structural diagram of a fixed-focus lens provided according to the first embodiment of the present utility model;

[0028] Figure 2 This is an MTF diagram of the fixed-focus lens provided according to the first embodiment of the present invention;

[0029] Figure 3 This is a relative illumination diagram of the fixed-focus lens provided according to the first embodiment of the present utility model;

[0030] Figure 4 This is an optical distortion diagram of the fixed-focus lens provided according to the first embodiment of the present utility model;

[0031] Figure 5 This is a schematic structural diagram of a fixed-focus lens provided according to the second embodiment of the present utility model;

[0032] Figure 6 This is an MTF diagram of the fixed-focus lens provided in Example 2 of the present utility model;

[0033] Figure 7 This is a relative illumination diagram of the fixed-focus lens provided in Example 2 of the present utility model;

[0034] Figure 8 This is an optical distortion diagram of the fixed-focus lens provided according to the second embodiment of the present utility model;

[0035] Figure 9 1 is a schematic structural diagram of a fixed-focus lens provided according to the third embodiment of the present invention;

[0036] Figure 10 This is an MTF diagram of the fixed-focus lens provided in Example 3 of the present utility model;

[0037] Figure 11 This is a relative illumination diagram of a fixed-focus lens provided according to the third embodiment of the present utility model;

[0038] Figure 12 This is an optical distortion diagram of the fixed-focus lens provided according to the third embodiment of the present utility model; DETAILED DESCRIPTION

[0039] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the present invention described herein can be implemented in an order other than that illustrated or described herein.

[0041] Figure 1 1 is a schematic structural diagram of a fixed-focus lens provided according to the first embodiment of the present utility model; Figure 5 This is a schematic structural diagram of a fixed-focus lens provided according to the second embodiment of the present utility model; Figure 9 : is a structural diagram of a fixed-focus lens provided according to the third embodiment of the present utility model; Figure 1 、 Figure 5 and Figure 9 As shown, the fixed-focus lens includes a first lens L1 with negative optical power, a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, a fifth lens L5 with optical power, a sixth lens L6 with optical power, a seventh lens L7 with positive optical power, an eighth lens L8 with positive optical power, a ninth lens L9 with optical power, and a tenth lens L10 with optical power, which are arranged in sequence from the object side to the image side.

[0042] The fifth lens L5 and the sixth lens L6 are cemented together to form a first cemented lens with negative refractive power, and the ninth lens L9 and the tenth lens L10 are cemented together to form a second cemented lens with positive refractive power.

[0043] It should be noted that the optical power is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the optical power, the stronger the ability to bend light, and the smaller the absolute value of the optical power, the weaker the ability to bend light. When the optical power is a positive number, the refraction of light is convergent; when the optical power is a negative number, the refraction of light is divergent. The optical power 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, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group). Reasonable distribution of the lens optical power allows light to be smooth during propagation and not be excessively deflected on a certain surface, so as to avoid introducing greater aberrations.

[0044] A filter PL and a photosensitive element are also provided on the image side. An aperture stop STO is disposed between the fourth lens L4 and the fifth lens L5.

[0045] The first lens L1 is a negative lens, capable of collecting light with a wide field of view and transferring it to the second lens L2. Both the second and third lenses L2 and L3 are positive lenses, converging the collected light for smooth transmission to the fourth lens L4. This reduces the light's entrance height, reduces the back port diameter, and achieves miniaturization. The fourth lens L4 is a negative lens, diverging the light. The arrangement of the first through fourth lenses L1 through L4 allows light to pass through the aperture and reach the first cemented lens. The negative focal power of the first cemented lens expands the light after passing through the aperture, minimizing aberrations. The light is then smoothly transmitted to the seventh and eighth lenses L7 and L8, where it is refocused and transmitted to the second cemented lens, where it is diverged for collection by the photosensitive element. Lenses L1 through L10 are all made of spherical glass, adaptable to varying temperatures, offering excellent temperature control and a long service life and stability.

[0046] Alternatively, as Figure 1 As shown in the figure, the object-side surface of the first lens L1 is concave, and the image-side surface is concave; the object-side surface of the second lens L2 is convex, and the image-side surface is convex; the object-side surface of the third lens L3 is convex, and the image-side surface is convex; the object-side surface of the fourth lens L4 is convex, and the image-side surface is concave; the object-side surface of the fifth lens L5 is concave, and the image-side surface is concave; the object-side surface of the sixth lens L6 is convex, and the image-side surface is convex; the object-side surface of the seventh lens L7 is convex, and the image-side surface is convex; the object-side surface of the eighth lens L8 is convex, and the image-side surface is convex; the object-side surface of the ninth lens L9 is convex, and the image-side surface is concave; and the object-side surface of the tenth lens L10 is convex, and the image-side surface is convex.

[0047] Alternatively, as Figure 5As shown in the figure, the object-side surface of the first lens L1 is convex, and the image-side surface is concave; the object-side surface of the second lens L2 is concave, and the image-side surface is convex; the object-side surface of the third lens L3 is convex, and the image-side surface is convex; the object-side surface of the fourth lens L4 is convex, and the image-side surface is concave; the object-side surface of the fifth lens L5 is concave, and the image-side surface is concave; the object-side surface of the sixth lens L6 is convex, and the image-side surface is convex; the object-side surface of the seventh lens L7 is convex, and the image-side surface is convex; the object-side surface of the eighth lens L8 is convex, and the image-side surface is convex; the object-side surface of the ninth lens L9 is convex, and the image-side surface is concave; and the object-side surface of the tenth lens L10 is convex, and the image-side surface is concave.

[0048] Alternatively, as Figure 9 As shown in the figure, the object-side surface of the first lens L1 is concave, and the image-side surface is concave; the object-side surface of the second lens L2 is convex, and the image-side surface is convex; the object-side surface of the third lens L3 is convex, and the image-side surface is concave; the object-side surface of the fourth lens L4 is convex, and the image-side surface is concave; the object-side surface of the fifth lens L5 is concave, and the image-side surface is concave; the object-side surface of the sixth lens L6 is convex, and the image-side surface is convex; the object-side surface of the seventh lens L7 is convex, and the image-side surface is convex; the object-side surface of the eighth lens L8 is convex, and the image-side surface is convex; the object-side surface of the ninth lens L9 is convex, and the image-side surface is concave; and the object-side surface of the tenth lens L10 is convex, and the image-side surface is concave.

[0049] Among them, by making corresponding convex and concave designs on the object side and image side of each lens, the trend of light can be changed and deflected, and aberration and chromatic aberration can be reduced.

[0050] Optionally, the focal powers of the first lens L1 to the tenth lens L10 and the focal power of the fixed-focus lens satisfy the following relationship:

[0051] in, is the optical focal length.

[0052] in, is the focal length of the fixed-focus lens, The optical powers of the first lens L1 through the tenth lens L10 are arranged in order. By properly arranging the optical powers of the first lens L1 through the tenth lens L10, light can be transmitted smoothly without excessive deflection on any surface, achieving good image quality and reducing aberrations and sensitivity.

[0053] Optionally, a curvature radius R41 on the object side of the fourth lens L4, a curvature radius R42 on the image side, and an axial thickness D4 of the fourth lens L4 satisfy the following relationship:

[0054] 0.02≤||R41-R42|-D4|≤1.55. Reasonable design of the curvature of both sides of the lens is beneficial to meeting the system functionality while facilitating lens processing.

[0055] Optionally, the curvature radius R51 on the object plane side of the first cemented lens, the curvature radius R62 on the image plane side, and the axial thickness D56 of the first cemented lens satisfy the following relationship:

[0056] 0.05≤||R51-R62|-D56|≤1.55. Reasonable design of the curvature of both sides of the lens is beneficial to meeting the system functionality while facilitating lens processing.

[0057] Optionally, the refractive indices of the first lens L1 to the tenth lens L10 satisfy the following relationship:

[0058] 1.75≤n1≤1.85;1.60≤n2≤1.65;1.80≤n3≤1.85;1.60≤n4≤1.65;

[0059] 1.80≤n5≤1.85;1.60≤n6≤1.65;1.55≤n7≤1.60;1.60≤n8≤1.65;

[0060] 1.60≤n9≤1.70; 1.45≤n8≤1.55, where n is the refractive index.

[0061] Among them, n1, n2, n3, n4, n5, n6, n7, n8, n9, and n10 are the refractive indices of the first lens L1 to the tenth lens L10 respectively.

[0062] Optionally, the Abbe numbers of the first lens L1 to the tenth lens L10 satisfy the following relationship:

[0063] 25.5≤v1≤30.0;55.0≤v2≤57.0;37.0≤v3≤37.5;58.0≤v4≤60.5;

[0064] 25.0≤v5≤25.5;63.0≤v6≤63.5;68.0≤v7≤69.0;55.0≤v8≤57.0;

[0065] 56.5≤v9≤58.5; 80.5≤v8≤82.0, where v is the Abbe number.

[0066] It should be noted that v1, v2, v3, v4, v5, v6, v7, v8, v9, and v10 are the Abbe numbers of the first lens L1 to the tenth lens L10, respectively.

[0067] By properly configuring the refractive index and Abbe number of the first lens L1 to the tenth lens L10, the chromatic aberration of the optical lens can be improved and corrected.

[0068] The present invention also provides a machine vision device, comprising the fixed-focus lens provided in any embodiment of the present invention, wherein the fixed-focus lens is applied to a machine vision lens.

[0069] The present invention proposes a fixed-focus lens and machine vision device. The fixed-focus lens comprises a first lens L1 with negative optical power, a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, a fifth lens L5 with optical power, a sixth lens L6 with optical power, a seventh lens L7 with positive optical power, an eighth lens L8 with positive optical power, a ninth lens L9 with optical power, and a tenth lens L10 with optical power, arranged sequentially from the object side to the image side. The fifth lens L5 and the sixth lens L6 are cemented together to form a first cemented lens with negative optical power, and the ninth lens L9 and the tenth lens L10 are cemented together to form a second cemented lens with positive optical power. The fixed-focus lens has a focal length of 16 mm and a field of view of 39.4°. The lens exhibits TV distortion of less than 0.04% and optical distortion of less than 0.4%, and operates stably at temperatures between 10°C and 50°C.

[0070] The following describes the fixed-focus lens proposed by the present invention with reference to specific embodiments. Table 1 is a table showing the specific data of various embodiments of the present invention.

[0071] Table 1 Specific data table of the utility model embodiment 1 to embodiment 3

[0072]

[0073]

[0074] In Example 1, the fixed-focus lens meets the following parameters: focal length: 16.17mm; aperture: F1.4; field of view: 39.3°; total optical length: 76.00mm, total axial length: 67.97mm. Table 2 shows the physical parameters of each lens in the fixed-focus lens of Example 1.

[0075] Table 2 Physical parameters of each lens in the fixed focus lens of Example 1

[0076] Surface number Surface Radius of curvature thickness Material (n) Materials (v) Semi-diameter S1 spherical surface -1342.948 2.000 1.785 25.720 10.439 S2 spherical surface 23.203 12.123 9.691 S3 spherical surface 50.338 2.327 1.639 55.45 9.930 S4 spherical surface -142.453 0.096 9.868 S5 spherical surface 27.919 2.898 1.834 37.211 9.574 S6 spherical surface -203.334 0.784 9.317 S7 spherical surface 15.431 8.023 1.620 60.339 7.965 S8 spherical surface 7.385 3.452 5.025 STO spherical surface unlimited 3.883 4.676 S10 spherical surface -7.187 0.800 1.805 25.456 4.709 S11 spherical surface 401.000 4.190 1.618 63.406 5.470 S12 spherical surface -10.896 0.100 6.498 S13 spherical surface 142.716 3.358 1.593 68.342 7.737 S14 spherical surface -16.170 0.100 8.057 S15 spherical surface 58.831 2.283 1.639 55.446 8.423 S16 spherical surface -52.822 4.059 Focus on demand 8.449 S17 spherical surface 23.344 -2.223 1.623 58.154 8.202 S18 spherical surface 8.907 1.500 1.497 81.612 7.508 S19 spherical surface -331.600 5.000 7.414 S20 spherical surface PL 2.8 1.517 64.198 6.309

[0077] In Table 2, the surface numbers are numbered according to the order of the surfaces of each lens. For example, the surface number "S1" represents the object side surface of the first lens, the surface number "S2" represents the image side surface of the first lens, and so on; "STO" represents the aperture of the lens; the radius of curvature represents the degree of curvature of the lens surface, a positive value represents that the surface is bent toward the object side with the center close to the image side, and a negative value represents that the surface is bent toward the image side with the center close to the object side; the thickness represents the axial distance from the center of the current surface to the next surface; the material (n) represents the refractive index, that is, the ability of the material between the current surface and the next surface to deflect light; a blank space represents that the current position is air with a refractive index of 1; the material (v) represents the Abbe number, that is, the dispersion characteristics of the material between the current surface and the next surface to light; a blank space represents that the current position is air.

[0078] Figure 2 is an MTF diagram of the fixed-focus lens provided according to the first embodiment of the present invention; wherein, Figure 2 The solid line represents the meridian, and the dotted line represents the sagittal. (Black represents the diffraction limit, blue represents 0.0000mm, green represents 1.0000mm, red represents 2.0000mm, yellow represents 3.3000mm, purple represents 4.4000mm, and cyan represents 5.5000mm.) The MTF values ​​of light of different wavelengths (0.436μm, 0.580μm, 0.656μm) and different fields of view are relatively high, 160lp / mm ≥ 0.2, indicating that the lens can well meet the needs of machine vision. Figure 3 This is a relative illumination diagram of the fixed-focus lens provided in Example 1 of the present invention (wavelength is 486nm). The ordinate is the normalized relative illumination value, and the abscissa is the corresponding field of view. It can be seen from the figure that the relative illumination of the edge field of view of the optical system is higher than 47%, and the imaging uniformity is good. Figure 4 : is an optical distortion diagram of the fixed-focus lens provided according to the first embodiment of the present utility model, wherein: Figure 4 The solid line in the middle represents the meridian, the dashed line represents the sagittal, and blue represents a wavelength of 436 nm, green represents 486 nm, red represents 546 nm, yellow represents 587 nm, and purple represents 656 nm. The ordinate represents the field of view (FOV) angle, and the abscissa represents the corresponding FOV. The figure shows that the maximum optical distortion of this optical system is less than 0.4%, and the image reproduction is excellent, meeting the requirements of machine vision. The maximum FOV is 18.482°, the sagittal curvature is 0.0607 mm, and the meridional curvature is 0.0426 mm. The maximum distortion is 0.2508%.

[0079] In Example 2, the fixed-focus lens meets the following parameters: focal length: 16.17mm; aperture: F1.4; field of view: 38.8°; total optical length: 76.00mm, total axial length: 67.96mm. Table 3 shows the physical parameters of each lens in Example 2.

[0080] Table 3 Physical parameters of each lens in the fixed focus lens of Example 2

[0081]

[0082]

[0083] In Table 3, the surface numbers are numbered according to the order of the surfaces of each lens. For example, the surface number "S1" represents the object side surface of the first lens, the surface number "S2" represents the image side surface of the first lens, and so on; "STO" represents the aperture of the lens; the radius of curvature represents the degree of curvature of the lens surface, a positive value represents that the surface is bent toward the object side with the center close to the image side, and a negative value represents that the surface is bent toward the image side with the center close to the object side; the thickness represents the axial distance from the center of the current surface to the next surface; the material (n) represents the refractive index, that is, the ability of the material between the current surface and the next surface to deflect light, and a blank space represents that the current position is air with a refractive index of 1; the material (v) represents the Abbe number, that is, the dispersion characteristics of the material between the current surface and the next surface to light, and a blank space represents that the current position is air.

[0084] Figure 6 This is the MTF diagram of the fixed-focus lens provided according to the second embodiment of the present invention, wherein: Figure 6 The solid line represents the meridian, and the dotted line represents the sagittal. (Black represents the diffraction limit, blue represents 0.0000mm, green represents 1.0000mm, red represents 2.0000mm, yellow represents 3.3000mm, purple represents 4.4000mm, and cyan represents 5.5000mm.) The MTF values ​​of light of different wavelengths (0.436μm, 0.580μm, 0.656μm) and different fields of view are relatively high, with 160lp / mm ≥ 0.15, indicating that the lens can well meet the needs of machine vision. Figure 7 This is a relative illumination diagram of the fixed-focus lens provided in Example 2 of the present invention (wavelength is 486nm). The ordinate is the normalized relative illumination value, and the abscissa is the corresponding field of view. It can be seen from the figure that the relative illumination of the edge field of view of the optical system is higher than 45%, and the imaging uniformity is good. Figure 8 This is an optical distortion diagram of the fixed-focus lens provided according to the second embodiment of the present utility model, wherein: Figure 8The solid line in the middle represents the meridian, the dashed line represents the sagittal, blue represents a wavelength of 436 nm, green represents a wavelength of 486 nm, red represents a wavelength of 546 nm, yellow represents a wavelength of 587 nm, and purple represents a wavelength of 656 nm. The ordinate represents the field of view (FOV) angle, and the abscissa represents the corresponding FOV. The figure shows that the maximum optical distortion of this optical system is less than 0.4%, and the image reproduction is good enough to meet machine vision requirements. The maximum FOV is 18.726°, the sagittal field curvature is 0.0461 mm, and the meridional field curvature is 0.0203 mm. The maximum distortion is 0.3635%.

[0085] In Example 3, the fixed-focus lens meets the following parameters: focal length: 16.17mm; aperture: F1.4; field of view: 39.18°; total optical length: 76.02mm, total axial length: 67.97mm. Table 4 shows the physical parameters of each lens in the fixed-focus lens of Example 3.

[0086] Table 4 Physical parameters of each lens in the fixed focus lens of Example 3

[0087]

[0088]

[0089] In Table 4, the surface numbers are numbered according to the order of the surfaces of each lens. For example, the surface number "S1" represents the object side surface of the first lens, the surface number "S2" represents the image side surface of the first lens, and so on; "STO" represents the aperture of the lens; the radius of curvature represents the degree of curvature of the lens surface, a positive value represents that the surface is bent toward the object side with the center close to the image side, and a negative value represents that the surface is bent toward the image side with the center close to the object side; the thickness represents the axial distance from the center of the current surface to the next surface; the material (n) represents the refractive index, that is, the ability of the material between the current surface and the next surface to deflect light; a blank space represents that the current position is air with a refractive index of 1; the material (v) represents the Abbe number, that is, the dispersion characteristics of the material between the current surface and the next surface to light; a blank space represents that the current position is air.

[0090] Figure 10 This is the MTF diagram of the fixed-focus lens provided according to the third embodiment of the present invention, wherein: Figure 10 The solid line represents the meridian, and the dotted line represents the sagittal. (Black represents the diffraction limit, blue represents 0.0000mm, green represents 1.0000mm, red represents 2.0000mm, yellow represents 3.3000mm, purple represents 4.4000mm, and cyan represents 5.5000mm.) The MTF values ​​of light of different wavelengths (0.436μm, 0.580μm, 0.656μm) and different fields of view are relatively high, with 160lp / mm ≥ 0.15, indicating that the lens can well meet the needs of machine vision. Figure 11 This is a relative illumination diagram of the fixed-focus lens provided in Example 3 of the present invention (wavelength is 486nm). The ordinate is the normalized relative illumination value, and the abscissa is the corresponding field of view. It can be seen from the figure that the relative illumination of the edge field of view of the optical system is higher than 45%, and the imaging uniformity is good. Figure 12 This is an optical distortion diagram of the fixed-focus lens provided according to the third embodiment of the present invention, wherein: Figure 12 The solid line in the middle represents the meridian, the dashed line represents the sagittal, and blue represents a wavelength of 436 nm, green represents 486 nm, red represents 546 nm, yellow represents 587 nm, and purple represents 656 nm. The ordinate represents the field of view (FOV) angle, and the abscissa represents the corresponding FOV. The figure shows that the maximum optical distortion of this optical system is less than 0.4%, and the image reproduction is excellent, meeting the requirements of machine vision. The maximum FOV is 18.665°, the sagittal curvature is 0.0539 mm, and the meridional curvature is 0.0321 mm. The maximum distortion is 0.3374%.

[0091] The above specific embodiments do not limit the scope of protection of this utility model. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model shall be included within the scope of protection of this utility model.

Claims

1. A fixed-focus lens, characterized in that: The lens comprises a first lens having negative optical power, a second lens having positive optical power, a third lens having positive optical power, a fourth lens having negative optical power, a fifth lens having optical power, a sixth lens having optical power, a seventh lens having positive optical power, an eighth lens having positive optical power, a ninth lens having optical power, and a tenth lens having optical power, which are arranged in sequence from the object side to the image side. The fifth lens and the sixth lens are cemented together to form a first cemented lens with negative optical power, and the ninth lens and the tenth lens are cemented together to form a second cemented lens with positive optical power.

2. The fixed-focus lens according to claim 1, wherein: The object-side surface of the first lens is concave, and the image-side surface is concave; the object-side surface of the second lens is convex, and the image-side surface is convex; the object-side surface of the third lens is convex, and the image-side surface is convex; the object-side surface of the fourth lens is convex, and the image-side surface is concave; the object-side surface of the fifth lens is concave, and the image-side surface is concave; the object-side surface of the sixth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is convex, and the image-side surface is convex; the object-side surface of the eighth lens is convex, and the image-side surface is convex; the object-side surface of the ninth lens is convex, and the image-side surface is concave; and the object-side surface of the tenth lens is convex, and the image-side surface is convex.

3. The fixed-focus lens according to claim 1, wherein: The object-side surface of the first lens is convex, and the image-side surface is concave; the object-side surface of the second lens is concave, and the image-side surface is convex; the object-side surface of the third lens is convex, and the image-side surface is convex; the object-side surface of the fourth lens is convex, and the image-side surface is concave; the object-side surface of the fifth lens is concave, and the image-side surface is concave; the object-side surface of the sixth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is convex, and the image-side surface is convex; the object-side surface of the eighth lens is convex, and the image-side surface is convex; the object-side surface of the ninth lens is convex, and the image-side surface is concave; and the object-side surface of the tenth lens is convex, and the image-side surface is concave.

4. The fixed-focus lens according to claim 1, wherein: The object-side surface of the first lens is concave, and the image-side surface is concave; the object-side surface of the second lens is convex, and the image-side surface is convex; the object-side surface of the third lens is convex, and the image-side surface is concave; the object-side surface of the fourth lens is convex, and the image-side surface is concave; the object-side surface of the fifth lens is concave, and the image-side surface is concave; the object-side surface of the sixth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is convex, and the image-side surface is convex; the object-side surface of the eighth lens is convex, and the image-side surface is convex; the object-side surface of the ninth lens is convex, and the image-side surface is concave; and the object-side surface of the tenth lens is convex, and the image-side surface is concave.

5. The fixed-focus lens according to claim 1, wherein: The focal powers of the first to tenth lenses and the focal power of the fixed-focus lens satisfy the following relationship: -0.57<φ1 / φ<-0.45; 0.12<φ2 / φ<0.301; 0.54<φ3 / φ<0.69; -0.52<φ4 / φ<-0.345 ;-1.87<φ5 / φ<-1.825; 0.91<φ6 / φ<0.99; 0.65<φ7 / φ<0.695; 0.23<φ8 / φ<0.38; 0.67<φ9 / φ<0.72; -0.928<φ10 / φ<-0.920, where φ is the optical power.

6. The fixed-focus lens according to claim 1, wherein: The curvature radius R41 on the object side of the fourth lens, the curvature radius R42 on the image side, and the axial thickness D4 of the fourth lens satisfy the following relationship: 0.02≤||R41-R42|-D4|≤1.

55.

7. The fixed-focus lens according to claim 1, wherein: The following relationship is satisfied between the radius of curvature R51 on the object side of the first cemented lens, the radius of curvature R62 on the image side, and the axial thickness D56 of the first cemented lens: 0.05≤||R51-R62|-D56|≤1.

55.

8. The fixed-focus lens according to claim 1, wherein: The refractive indices of the first lens to the tenth lens satisfy the following relationship: 1.75≤n1≤1.85;1.60≤n2≤1.65;1.80≤n3≤1.85;1.60≤n4≤1.65; 1.80≤n5≤1.85;1.60≤n6≤1.65;1.55≤n7≤1.60;1.60≤n8≤1.65; 1.60≤n9≤1.70; 1.45≤n8≤1.55, where n is the refractive index.

9. The fixed-focus lens according to claim 1, wherein: The Abbe numbers of the first lens to the tenth lens satisfy the following relationship: 25.5≤v1≤30.0;55.0≤v2≤57.0;37.0≤v3≤37.5;58.0≤v4≤60.5; 25.0≤v5≤25.5;63.0≤v6≤63.5;68.0≤v7≤69.0;55.0≤v8≤57.0; 56.5≤v9≤58.5; 80.5≤v8≤82.0, where v is the Abbe number.

10. A machine vision device, characterized in that: The fixed-focus lens comprises the fixed-focus lens according to any one of claims 1 to 9, wherein the fixed-focus lens is applied to a machine vision lens.

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