Sammer lens and industrial camera comprising same

Abstract

The invention provides a Gamma lens and an industrial camera comprising the Gamma lens, the Gamma lens is an optical imaging system, and the Gamma lens sequentially comprises a first lens to a ninth lens with specific diopters and surface types and a diaphragm from an object side to an image side along an optical axis; by optimizing lens configuration, material matching and optical parameters, the problems of small target surface, easy thermal defocus, small inclination angle, small numerical aperture and the like in the prior art are effectively solved; the lens has the advantages of a large imaging target surface (the diameter of an imaging ring is 22 mm), good athermalization performance (the working temperature range is-20 DEG C to + 60 DEG C), a large object plane inclination angle (larger than 50 degrees), a large numerical aperture (NA = 0.12), a specific working wave band (395-415 nm) and the like, and the imaging quality, the environmental adaptability and the measurement precision in the fields of machine vision, 3D measurement and the like are remarkably improved; the invention also discloses an industrial camera comprising the Sammer lens.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a SAM lens and an industrial camera incorporating the SAM lens. Background Technology

[0002] With the rapid development of industrial automation technology, 3D vision measurement equipment is widely used in product dimension inspection, 3D modeling, quality monitoring, and other fields, which places increasingly higher demands on the performance of optical lenses. Scham lenses, by tilting the imaging plane, align the object plane, the principal plane of the lens, and the image plane in a single line (Scham's Law), thus enabling the acquisition of clear images over a large depth of field. They are a core component of 3D measurement systems such as line laser scanning.

[0003] However, existing SAM lenses have many limitations: 1) The imaging target surface is small, which cannot be adapted to large-size photosensitive elements, limiting the field of view of a single measurement; 2) They lack effective calorimetry design, and are prone to defocusing and blurring due to thermal expansion and contraction of materials in high and low temperature environments (such as the -20℃~+60℃ common in industrial sites); 3) The allowable object tilt angle is small, which limits the achievable measurement depth of field; 4) The numerical aperture (NA) is small, resulting in insufficient light transmission. In low-light environments, the exposure time needs to be extended, which easily produces motion blur, affecting measurement speed and accuracy.

[0004] Therefore, there is an urgent need for a high-performance SAM lens with a large target area, no pyrolysis, a large tilt angle, and a large numerical aperture to meet the needs of modern high-precision, high-efficiency, and highly environmentally adaptable 3D measurement. Summary of the Invention

[0005] This invention provides a SAM lens that can effectively solve the above-mentioned problems.

[0006] This invention is implemented as follows: A SAM lens, as an optical imaging system, comprises, in sequence along the optical axis from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, an aperture stop, a sixth lens, a seventh lens, an eighth lens, and a ninth lens. The first lens has positive diopter and the object-side surface is convex. The second lens has positive diopter, with the object-side surface being convex and the image-side surface being concave. The third lens has positive diopter, with the object-side surface being convex and the image-side surface being concave. The fourth lens has positive diopter, with the object-side surface being convex and the image-side surface being concave. The fifth lens has negative refractive power, with the object-side surface being convex and the image-side surface being concave. The sixth lens has negative refractive power, with the object-side surface being convex and the image-side surface being concave. The seventh lens has negative refractive power, and the object side is concave and the image side is concave. The eighth lens has positive diopter, and the object side and the image side are both convex. The ninth lens is a biconvex lens with positive diopter.

[0007] As a further improvement, the radius of curvature of the object side of the first lens is set to be 57.07~53.94, and the radius of curvature of the image side of the first lens is set to be -245.33~-207.48. The radius of curvature of the object side of the second lens is set to be 21.33~21.44, and the radius of curvature of the image side of the second lens is set to be 46.08~47.7. The radius of curvature of the object side of the third lens is set to be 16.98~17.73, and the radius of curvature of the image side of the third lens is set to be 28.03~28.91. The radius of curvature of the object side of the fourth lens is set to be 12.26~13.43, and the radius of curvature of the image side of the fourth lens is set to be 18.18~21.1.

[0008] As a further improvement, the radius of curvature of the object side of the fifth lens is set to be 19.71~22.7, and the radius of curvature of the image side of the fifth lens is set to be 9.65~10.42. The radius of curvature of the object side of the sixth lens is set to be 19.05~19.17, and the radius of curvature of the image side of the sixth lens is set to be 10.22~10.65. The radius of curvature of the object-side surface of the seventh lens is set to -32.55 to -32.54. The radius of curvature of the object side of the eighth lens is set to 15.4~15.74, and the radius of curvature of the image side of the eighth lens is set to -31.62~-30.56. The radius of curvature of the object side of the ninth lens is set to 39.46~40.24, and the radius of curvature of the image side of the ninth lens is set to -91.34~-90.69.

[0009] As a further improvement, the thickness interval between the object side and the image side of the first lens is set to be 0.1~2.43. The thickness interval between the object-side surface and the image-side surface of the second lens is set to a range of 0.1~2.58. The thickness interval between the object side and the image side of the third lens is set to be 0.1~2.46. The thickness interval between the object side and the image side of the fourth lens is set to be 0.78~2.38.

[0010] As a further improvement, the thickness interval between the object side and the image side of the fifth lens is set to be 0.66~1.02. The thickness interval between the object side and the image side of the sixth lens is set to a range of 1 to 2.12. The thickness interval between the object side and the image side of the seventh lens is set to 1. The thickness interval between the object side and the image side of the eighth lens is set to be 2.76~7.55. The thickness interval between the object side and the image side of the ninth lens is set to be 3.16~26.94.

[0011] As a further improvement, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all made of glass.

[0012] As a further improvement, the refractive indices of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are set to 1.8, 1.8, 1.6, 1.5, 1.8, 1.5, 1.8, 1.5, and 1.9, respectively.

[0013] As a further improvement, the focal length range of the first lens is set to 56.9~57.6; The focal length range of the second lens is set to 46.8~47.5; The focal length range of the third lens is set to 65.4~70.3. The focal length range of the fourth lens is set to 65.4~66.

[0014] As a further improvement, the focal length range of the fifth lens is set to -21.9 to -21.7. The focal length range of the sixth lens is set to -50.4 to -45.6. The focal length range of the seventh lens is set to -12.6 to -12.4. The focal length range of the eighth lens is set to 20.6~21.1. The focal length range of the ninth lens is set to 30.2~30.6.

[0015] An industrial camera includes a window plate disposed along an optical path from the object side to the image side, a SAM lens as described above, and a photosensitive element; the window plate is coated with a specific film layer to filter out spectra other than the operating wavelength, and the window plate is disposed perpendicular to the optical axis.

[0016] Compared with the prior art, the beneficial effects of the present invention include: 1) Adopting a nine-element lens structure, rationally allocating positive and negative optical power and optimizing the surface shape, it achieves a large target surface (22mm imaging circle diameter) design, with less noise, high latitude, and good signal-to-noise ratio in low-light environments. It can be adapted to larger-sized photosensitive chips, expanding the field of view for single measurements.

[0017] 2) Through the matching design of the all-glass lens and the frame material, the non-thermal performance is achieved in a wide temperature range of -20℃ to +60℃. The back focus change is small and the image plane is stable under high and low temperature environments, effectively preventing thermal defocusing and preventing image blur caused by temperature drift.

[0018] 3) It has a large numerical aperture (NA=0.12), which allows for a large amount of light to pass through. This results in more light entering the camera within the same exposure time, which is beneficial for working in low-light environments, shortening the exposure time, avoiding motion blur, and making it suitable for environments with high ambient light. It also meets the needs of high-speed instantaneous image acquisition.

[0019] 4) It supports a large object tilt angle. Compared with the coaxial state, the tilt is >50°, which can meet the needs of a wide measurement depth range. Combined with the optimized Sham angle (35°<α<50°), the light difference between the far point and the near point of the object is equal in the tilt state, and the object is clearly imaged, thus ensuring that the sharpness of the far and near points on the tilted focal plane is consistent.

[0020] 5) The working spectrum is limited to the short-wavelength range of 395-415nm. By utilizing the diffraction limit advantage of the short-wavelength field, it can effectively suppress laser dispersion noise, reduce ambient light interference, improve the signal-to-noise ratio, and ensure that the laser line is uniformly focused on the tilted focal plane, avoiding line broadening caused by long-wavelength dispersion.

[0021] 6) It has a wide range of object distances, and can clearly image objects within the range of 81-102mm. It has a large depth of field and is highly practical.

[0022] 7) The magnification in coaxial mode is moderate, satisfying 0.3 < |M| < 0.9, so that the horizontal field of view meets the application requirements of 32mm.

[0023] 8) It maintains good imaging balance in both coaxial and tilted states, with excellent MTF performance, ensuring overall imaging quality.

[0024] 9) Industrial cameras incorporating this SAM lens further filter out stray light through coated windows, improving the system's signal-to-noise ratio and measurement accuracy. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is the optical path diagram of the Sham lens according to Embodiment 1 of the present invention.

[0027] Figure 2 The MTF of the Sham lens in Embodiment 1 of this invention under visible light Figure 1 .

[0028] Figure 3 The distortion of the Sham lens in Embodiment 1 of this invention under visible light Figure 1 .

[0029] Figure 4 The MTF of the Sham lens in Embodiment 1 of this invention under visible light Figure 2 .

[0030] Figure 5 The distortion of the Sham lens in Embodiment 1 of this invention under visible light Figure 2 .

[0031] Figure 6 This is the optical path diagram of the Sham lens in Embodiment 2 of the present invention.

[0032] Figure 7 The MTF of the Sham lens in Embodiment 2 of this invention under visible light Figure 1 .

[0033] Figure 8 The distortion of the Sham lens in the second embodiment of the present invention under visible light. Figure 1 .

[0034] Figure 9 The MTF of the Sham lens in Embodiment 2 of this invention under visible light Figure 2 .

[0035] Figure 10 The distortion of the Sham lens in the second embodiment of the present invention under visible light. Figure 2 .

[0036] Figure 11 This is the optical path diagram of the Sham lens according to Embodiment 3 of the present invention.

[0037] Figure 12 The MTF of the Sham lens in Embodiment 3 of this invention under visible light Figure 1 .

[0038] Figure 13 The distortion of the Sham lens in visible light according to Embodiment 3 of the present invention. Figure 1 .

[0039] Figure 14 The MTF of the Sham lens in Embodiment 3 of this invention under visible light Figure 2 .

[0040] Figure 15 The distortion of the Sham lens in visible light according to Embodiment 3 of the present invention. Figure 2 . Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0043] Reference Figures 1-15 As shown, a Sham lens, arranged sequentially along the optical axis from the object side to the image side, includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, an aperture stop, a sixth lens, a seventh lens, an eighth lens, and a ninth lens.

[0044] The first lens is a positive diopter lens with a convex object-side (the side facing the object); the second lens is a positive diopter lens with a convex object-side and a concave image-side (the side facing the image plane); the third lens is a positive diopter lens with a convex object-side and a concave image-side; the fourth lens is a positive diopter lens with a convex object-side and a concave image-side; the fifth lens is a negative diopter lens with a convex object-side and a concave image-side; the aperture stop is located after the fifth lens and is used to control the amount of light entering the lens; the sixth lens is a negative diopter lens with a convex object-side and a concave image-side; the seventh lens is a negative diopter lens with a concave object-side and a concave image-side; the eighth lens is a positive diopter lens with a convex object-side and a convex image-side; the ninth lens is a positive diopter biconvex lens.

[0045] The first, second, third, and fourth lenses form the front group, which mainly serves to improve optical power and correct aberrations. The fifth, sixth, seventh, eighth, and ninth lenses form the rear group, which is used to further balance phase aberrations, control image telecentrism, and achieve calorimetry.

[0046] Furthermore, the SAM lens has an image circle diameter of no less than 22mm, resulting in low noise, high dynamic range, and good signal-to-noise ratio in low-light environments. Moreover, within an operating temperature range of -20℃ to +60℃, the matching design of the all-glass lens and frame materials achieves heat-free operation, suppressing back focus changes under high and low temperature conditions within a preset range and preventing image blur caused by temperature drift. Additionally, the SAM lens has a numerical aperture (NA) of 0.12, providing a large light-gathering aperture and allowing for a greater amount of light to enter at the same time, effectively avoiding motion blur and making it suitable for environments with high ambient light levels, while also meeting the requirements for high-speed, instantaneous image acquisition.

[0047] Furthermore, the SAM lens allows for an object tilt angle greater than 50°, satisfying the requirement for a wide measurement depth of field. In addition, the magnification M of the SAM lens in coaxial mode satisfies 0.3 < |M| < 0.9, ensuring a horizontal field of view that meets the 32mm application requirement. Moreover, the SAM angle α of the SAM lens satisfies 35° < α < 50°, ensuring equal light aberration between the far and near points of the object in tilted mode, resulting in clear imaging of the object.

[0048] Furthermore, the Sham lens operates in the spectral range of 395nm to 415nm, leveraging the diffraction limit in short-wavelength fields to suppress laser dispersion noise. This spectral range is ideal for use with narrowband filters, while also reducing environmental interference, improving the signal-to-noise ratio, ensuring uniform focusing of the laser line on the tilted focal plane, and preventing line broadening due to long-wavelength dispersion. Moreover, the Sham lens achieves an MTF value greater than 0.4 at a spatial frequency of 50 lp / mm in a coaxial configuration and greater than 0.1 at the same spatial frequency in a tilted configuration. All lenses are made of optical glass, and the performance targets of this Sham lens are achieved through meticulous design of parameters such as the radius of curvature, thickness, spacing, refractive index, and Abbe number of each lens, and by selecting glass combinations that match the coefficient of thermal expansion of the lens barrel (frame) material.

[0049] The optical design parameters of this Sham lens are described in detail below through three specific embodiments.

[0050] In the tables of the various embodiments, "thickness interval" refers to the on-axis distance from the current surface to the next optical surface, and "focal length" refers to the focal length of a single lens.

[0051] Example 1: Reference Figures 1-5 The specific optical parameters of this embodiment are shown in Table 1. The first to fourth lenses all use high refractive index or special dispersion glass (e.g., refractive index 1.8, 1.5, Abbe number 52 to 82), forming a front group with strong positive optical power, which is beneficial for compressing the overall system length and correcting primary phase aberration. The fifth lens uses high refractive index, low Abbe number glass (refractive index 1.8, Abbe number 24), providing negative optical power to correct the positive spherical aberration and field curvature generated by the front group. The combination of the sixth and seventh lenses effectively controls Pets and field curvature. The combination of the eighth and ninth lenses uses medium to high refractive index glass with different dispersion characteristics (refractive index 1.5 / 1.9, Abbe number 82 / 39), providing the necessary positive optical power while achieving good chromatic aberration correction and thermal compensation.

[0052] Table 1: Optical Parameters Table for Example 1

[0053] Example 2: Reference Figures 6-10, this embodiment makes fine-tuning on the basis of Embodiment 1, optimizing the curvature, thickness and spacing of some lenses to adapt to more stringent tolerance requirements or achieve specific performance trade-offs. For example, the radius of curvature of the first lens is reduced, the thicknesses of the second and third lenses are slightly increased, and the radius of curvature of the fifth lens is increased. These adjustments help to further optimize the high-order aberrations and manufacturing sensitivities. This embodiment also achieves all the beneficial effects shown in Embodiment 1.

[0054] Table II: Optical Parameter Table of Embodiment 2

[0055] Embodiment 3: Referring to Figures 11-15 , the parameters of this embodiment are similar to those of Embodiment 2, only slightly different in the radius of curvature of the ninth lens (39.46 mm vs 39.56 mm), which shows that under the lens configuration of the Scheimpflug lens, the design parameters can be flexibly adjusted within a small range to adapt to the material characteristics of different batches or fine-tune the final system performance (such as back focal length, distortion, etc.) without departing from the protection scope of the present invention. This fine-tuning further proves the robustness and manufacturability of the Scheimpflug lens.

[0056] Table III: Optical Parameter Table of Embodiment 3

[0057] The Scheimpflug lens constructed based on any of the above embodiments can achieve the following comprehensive performance: The imaging circle diameter ≥ 22 mm; the numerical aperture NA = 0.12; the working spectral range is set at 395 - 415 nm; the support surface tilt angle > 50°; the Scheimpflug angle α is about 42°, that is, the Scheimpflug angle satisfies 35° < α < 50°; the coaxial magnification |M| is about 0.6, that is, the magnification satisfies 0.3 < |M| < 0.9; within the temperature range of -20°C to +60°C, athermalization is achieved through material matching and the change of the back focal length is extremely small; in the coaxial state, the MTF value at the spatial frequency of 50 lp / mm in the full field of view is greater than 0.4, and the corresponding MTF value in the maximum tilt state is greater than 0.1; clear imaging is achieved within the object distance range of 81 - 102 mm.

[0058] This invention also provides an industrial camera, comprising a window, the aforementioned Sham lens, and a photosensitive element (such as a CMOS or CCD sensor) arranged sequentially along the light incident direction. The window surface is coated with a bandpass filter film with a center wavelength matching the operating band of the Sham lens (e.g., 405nm), exhibiting a narrow half-width to efficiently filter out ambient stray light outside the operating band. The window is mounted strictly perpendicular to the optical axis. The photosensitive surface of the photosensitive element is located at the image plane (IMG) position of the Sham lens.

[0059] When this industrial camera is working, the laser lines (such as 405nm line laser) on the surface of the object being measured are filtered through a window and then imaged onto the photosensitive element through a SAM lens. Because the SAM lens has a large tilt angle, large numerical aperture, large target surface, and no pyrolysis characteristics, this camera can achieve high-speed, high-precision, and large depth-of-field 3D measurement of object contours in various complex industrial environments.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Sharm lens for an optical imaging system, characterized in that, Arranged sequentially along the optical axis from the object side to the image side are: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, an aperture stop, a sixth lens, a seventh lens, an eighth lens, and a ninth lens; The first lens has positive diopter and the object-side surface is convex. The second lens has positive diopter, with the object-side surface being convex and the image-side surface being concave. The third lens has positive diopter, with the object-side surface being convex and the image-side surface being concave. The fourth lens has positive diopter, with the object-side surface being convex and the image-side surface being concave. The fifth lens has negative refractive power, with the object-side surface being convex and the image-side surface being concave. The sixth lens has negative refractive power, with the object-side surface being convex and the image-side surface being concave. The seventh lens has negative refractive power, and the object side is concave and the image side is concave. The eighth lens has positive diopter, and the object side and the image side are both convex. The ninth lens is a biconvex lens with positive diopter.

2. The Sharm lens of claim 1, wherein, The radius of curvature of the object side of the first lens is set to be 57.07~53.94, and the radius of curvature of the image side of the first lens is set to be -245.33~-207.

48. The radius of curvature of the object side of the second lens is set to be 21.33~21.44, and the radius of curvature of the image side of the second lens is set to be 46.08~47.

7. The radius of curvature of the object side of the third lens is set to be 16.98~17.73, and the radius of curvature of the image side of the third lens is set to be 28.03~28.

91. The radius of curvature of the object side of the fourth lens is set to be 12.26~13.43, and the radius of curvature of the image side of the fourth lens is set to be 18.18~21.

1.

3. The Sharm lens of claim 1, wherein, The radius of curvature of the object side of the fifth lens is set to be 19.71~22.7, and the radius of curvature of the image side of the fifth lens is set to be 9.65~10.

42. The radius of curvature of the object side of the sixth lens is set to be 19.05~19.17, and the radius of curvature of the image side of the sixth lens is set to be 10.22~10.

65. The radius of curvature of the object-side surface of the seventh lens is set to -32.55 to -32.

54. The radius of curvature of the object side of the eighth lens is set to 15.4~15.74, and the radius of curvature of the image side of the eighth lens is set to -31.62~-30.

56. The radius of curvature of the object side of the ninth lens is set to 39.46~40.24, and the radius of curvature of the image side of the ninth lens is set to -91.34~-90.

69.

4. The Sharm lens of claim 1, wherein, The thickness interval between the object-side surface and the image-side surface of the first lens is set to a range of 0.1~2.

43. The thickness interval between the object-side surface and the image-side surface of the second lens is set to a range of 0.1~2.

58. The thickness interval between the object side and the image side of the third lens is set to be 0.1~2.

46. The thickness interval between the object side and the image side of the fourth lens is set to be 0.78~2.

38.

5. The Sharm lens of claim 1, wherein, The thickness interval between the object side and the image side of the fifth lens is set to be 0.66~1.

02. The thickness interval between the object side and the image side of the sixth lens is set to a range of 1 to 2.

12. The thickness interval between the object side and the image side of the seventh lens is set to 1. The thickness interval between the object side and the image side of the eighth lens is set to be 2.76~7.

55. The thickness interval between the object side and the image side of the ninth lens is set to be 3.16~26.

94.

6. The Sharm lens of claim 1, wherein, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are all made of glass.

7. The Sharm lens of claim 1, wherein, The refractive indices of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are set to 1.8, 1.8, 1.6, 1.5, 1.8, 1.5, 1.8, 1.5, and 1.9, respectively.

8. The Sharm lens of claim 1, wherein, The focal length range of the first lens is set to 56.9~57.6; The focal length range of the second lens is set to 46.8~47.5; The focal length range of the third lens is set to 65.4~70.

3. The focal length range of the fourth lens is set to 65.4~66.

9. The Sharm lens of claim 1, wherein, The focal length range of the fifth lens is set to -21.9 to -21.

7. The focal length range of the sixth lens is set to -50.4 to -45.

6. The focal length range of the seventh lens is set to -12.6 to -12.

4. The focal length range of the eighth lens is set to 20.6~21.

1. The focal length range of the ninth lens is set to 30.2~30.

6.

10. An industrial camera, characterized in that, The device includes a window plate disposed along the optical path from the object side to the image side, a Sham lens as described in any one of claims 1 to 9, and a photosensitive element; the window plate is coated with a specific film layer to filter out spectra other than the operating wavelength, and the window plate is disposed perpendicular to the optical axis.

Images