Large-aperture laser displacement sensor imaging lens and optical system thereof

Abstract

The present application relates to the technical field of optical measurement sensor, disclose a kind of large aperture laser displacement sensor imaging lens and its optical system.The optical system is sequentially arranged from object side to image side parallel protection glass plate G0, the first lens G1 with positive focal power, the second lens G2 with negative focal power, the third lens G3 with positive focal power, diaphragm A0, the fourth lens G4 with negative focal power and the fifth lens G5 with positive focal power are constituted.The optical system meets the stronger light collection ability, also comply with the requirement of current mainstream sensor shape size;In addition, the lens aberration is small, can effectively present the image of laser emission part.High resolution, the transition pixel of light spot presented on sensor is less, greatly improve the detection precision of displacement sensor.

Description

Technical Field

[0001] This invention relates to the field of optical measurement sensor technology, and in particular to a large-aperture laser displacement sensor imaging lens and its optical system. Background Technology

[0002] The mainstream technology for laser displacement sensors is laser triangulation, which achieves non-contact displacement measurement through three steps: laser emission, spot imaging, and triangulation calculation. Specifically, the sensor's built-in laser emitter projects a laser beam onto the surface of the object being measured. The diffusely reflected light from the object's surface is focused by the receiving lens, forming a spot on the detector (CCD / CMOS). When the object moves, the spot's position on the detector shifts. The system calculates the displacement distance based on the triangular geometric relationship formed by the laser emitter, imaging lens, and detector, combined with a pre-defined algorithm. In this measurement process, the imaging lens plays a crucial role in accurately focusing the diffusely reflected light from the measured surface onto the detector's image plane, thus determining the upper limit of the displacement sensor's measurement accuracy.

[0003] With the progress of industrialization, the application environments of laser displacement sensors are becoming increasingly complex. To adapt to more diverse detection environments and improve detection accuracy and sampling frequency, it is essential to equip them with high-resolution and large-aperture imaging lenses. Large-aperture lenses can improve light energy utilization, reduce sensor exposure time, and increase image acquisition rate. However, residual aberrations in existing laser displacement sensor lens designs increase the size of the diffuse spot on the detector and cause geometric shifts in the spot's centroid, thus significantly reducing the repeatability and absolute accuracy of displacement measurements.

[0004] Therefore, there is an urgent need in this field to develop a large-aperture laser displacement sensor imaging lens that has good resolution and a small spot size, provides good imaging effect during measurement, and has the ability to converge scattered light from the surface of the object being measured, so as to achieve clear spot focusing within the measurement range.

[0005] The above information is provided as background information only to aid in understanding this disclosure and does not constitute an assertion or admission that any of the above content can be used as prior art relative to this disclosure. Summary of the Invention

[0006] The purpose of this invention is to provide a large-aperture laser displacement sensor imaging lens and its optical system to solve or at least partially solve the technical problems existing in the prior art.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an optical system for an imaging lens of a large-aperture laser displacement sensor, comprising a parallel protective glass plate G0 arranged sequentially from the object side to the image side, a first lens G1 with positive optical power, a second lens G2 with negative optical power, a third lens G3 with positive optical power, an aperture stop A0, a fourth lens G4 with negative optical power, and a fifth lens G5 with positive optical power; wherein the second lens G2 and the third lens G3 form a cemented doublet lens U1; The optical system has a focal length of f', the first lens G1 has a focal length of f1, the second lens G2 has a focal length of f2, the third lens G3 has a focal length of f3, and the cemented doublet lens U1 has a focal length of f'. U1 The fourth lens G4 has a focal length of f4, and the fifth lens G5 has a focal length of f5, satisfying the following relationships: 1.0≤|f1 / f'|≤2.0, 0.1≤|f2 / f'|≤1.0, 0.1≤|f3 / f'|≤1.0, 4.0≤|f U1 / f'|≤5.0, 2.0≤|f4 / f'|≤3.0, 0.1≤|f5 / f'|≤1.0.

[0008] Optionally, the refractive index of the first lens G1 is n1, and the Abbe number is v1, satisfying the following relationships: 1.9≤n1≤2.0; 30≤v1≤40; The refractive index of the second lens G2 is n2, and the Abbe number is v2, satisfying the following relationships: 1.7≤n2≤1.8; 20≤v2≤30; The refractive index of the third lens G3 is n3, and the Abbe number is v3, satisfying the following relationships: 1.8≤n3≤1.9; 40≤v3≤50; The fourth lens G4 has a refractive index of n4 and an Abbe number of v4, satisfying the following relationships: 1.5≤n4≤1.6; 50≤v4≤60; The fifth lens G5 has a refractive index of n5 and an Abbe number of v5, satisfying the following relationships: 1.8≤n5≤1.9; 40≤v5≤50; Optionally, the first lens G1, the third lens G3, and the fifth lens G5 are all biconvex lenses, the second lens G2 is a biconcave lens, and the fourth lens G4 is a meniscus lens, with the convex surface of the fourth lens G4 facing the object side.

[0009] Optionally, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, and the fifth lens G5 are all glass spherical lenses, and the optical axes of all the glass spherical lenses coincide.

[0010] Optionally, the object height of the optical system is y', which satisfies the relationship: |y' / f'|≤1.0.

[0011] Optionally, the optical system has an F-number of 2.85, a working distance of 90 mm, and a measurement range of ±15.6 mm after being adapted to the optical path of the laser displacement sensor.

[0012] Optionally, the aperture of the aperture A0 is a circular aperture.

[0013] Secondly, the present invention provides a large-aperture laser displacement sensor imaging lens, including the optical system of the large-aperture laser displacement sensor imaging lens as described above.

[0014] Optionally, a reflector G6 is also provided between the fifth lens G5 and the image plane; the placement angle of the reflector G6 is determined by the spatial position of the image plane, and it is used to reflect the outgoing light from the fifth lens G5 to the image plane.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This application presents an optical system constructed through the rational combination of multiple lenses. The lens has an F-number of 2.85, which satisfies both strong light-gathering capabilities and meets the current mainstream sensor size requirements. Furthermore, the lens has low aberrations, effectively capturing the image of the laser emission portion. High resolution and fewer transition pixels in the light spot projected onto the sensor significantly improve the detection accuracy of the displacement sensor.

[0016] The present invention has other features and advantages, which will be apparent from or will be set forth in detail in the accompanying drawings and the following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the optical system of a large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention.

[0019] Figure 2 for Figure 1 Optical path diagram Figure 3 A dot diagram of an optical system for a large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention.

[0020] Figure 4The MTF diagram of an optical system for a large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the optical system of another large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention.

[0022] Figure 6 for Figure 5 The optical path diagram.

[0023] Figure 7 A dot diagram of an optical system for another large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention.

[0024] Figure 8 MTF diagram of an optical system for a large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention. Detailed Implementation

[0025] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0026] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0027] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0028] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0029] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0030] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0031] As understood in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0032] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0033] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0034] Example 1: Please see Figure 1 , Figure 1 This is a schematic diagram of the optical system of a large-aperture laser displacement sensor imaging lens provided in an embodiment of the present invention.

[0035] like Figure 1 As shown, the optical system consists of a parallel protective glass plate G0 arranged sequentially from the object side to the image side, a first lens G1 with positive optical power, a second lens G2 with negative optical power, a third lens G3 with positive optical power, an aperture stop A0, a fourth lens G4 with negative optical power, and a fifth lens G5 with positive optical power; wherein, the second lens G2 and the third lens G3 form a cemented doublet lens U1; The optical system has a focal length of f', the first lens G1 has a focal length of f1, the second lens G2 has a focal length of f2, the third lens G3 has a focal length of f3, and the cemented doublet lens U1 has a focal length of f'. U1 The fourth lens G4 has a focal length of f4, and the fifth lens G5 has a focal length of f5, satisfying the following relationships: 1.0≤|f1 / f'|≤2.0, 0.1≤|f2 / f'|≤1.0, 0.1≤|f3 / f'|≤1.0, 4.0≤|f U1 / f'|≤5.0, 2.0≤|f4 / f'|≤3.0, 0.1≤|f5 / f'|≤1.0.

[0036] Furthermore, the refractive index of the first lens G1 is n1, and the Abbe number is v1, satisfying the following relationships: 1.9≤n1≤2.0; 30≤v1≤40; The refractive index of the second lens G2 is n2, and the Abbe number is v2, satisfying the following relationships: 1.7≤n2≤1.8; 20≤v2≤30; The refractive index of the third lens G3 is n3, and the Abbe number is v3, satisfying the following relationships: 1.8≤n3≤1.9; 40≤v3≤50; The fourth lens G4 has a refractive index of n4 and an Abbe number of v4, satisfying the following relationships: 1.5≤n4≤1.6; 50≤v4≤60; The fifth lens G5 has a refractive index of n5 and an Abbe number of v5, satisfying the following relationships: 1.8≤n5≤1.9; 40≤v5≤50; Specifically, the first lens G1, the third lens G3, and the fifth lens G5 are all biconvex lenses, the second lens G2 is a biconcave lens, and the fourth lens G4 is a meniscus lens, with the convex surface of the fourth lens G4 facing the object side.

[0037] In this embodiment, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, and the fifth lens G5 are all glass spherical lenses, and the optical axes of all the glass spherical lenses coincide.

[0038] Specifically, the object height of the optical system is y', which satisfies the relationship: |y' / f'|≤1.0.

[0039] The optical system provided in this embodiment has an F-number of 2.85, a working distance of 90 mm, and a measurement range of ±15.6 mm after being adapted to the optical path of a laser displacement sensor.

[0040] In this embodiment, the aperture of the stop A0 is a circular aperture, and the aperture value of the stop A0 can be adjusted according to specific needs.

[0041] Furthermore, two application examples are given below, as follows: Example 1: The optical system in Example 1 is as follows Figure 1 As shown, the relevant data for this optical system are presented in Tables 1 to 3: Table 1 Table 2 Table 3 Table 1 shows the imaging lens parameters of the laser displacement sensor, Table 2 shows the focal length and object height of each lens, and Table 3 shows the ratio of the focal lengths of each lens.

[0042] In this example, the focal length of the imaging lens is 32.87mm, and the total length of the lens is 34.1mm.

[0043] Figure 3 The dot plot of the imaging lens in Example 1 shows that the root mean square radius of the entire field of view is less than 4μm at a working wavelength of 650nm. This indicates that the optical system has high energy concentration. The dot plot shows that the optical system has high resolution, small spot size and good aberration balance under the full field of view, making it suitable for high-precision laser displacement sensors used in harsh environments.

[0044] Figure 4 The MTF plot of the imaging lens in Example 1 shows that at a meridional spatial frequency of 30 lp / mm across the entire field of view, the modulation transfer function (MTF) value is greater than 0.8. The entire MTF curve exhibits a smooth, monotonically decreasing trend, without any abnormal local dips or steps, indicating that the optical system has no obvious abnormal aberrations or structural defects. At the Nyquist frequency of the detector (50 lp / mm), the MTF values ​​across the entire field of view are all greater than 0.65, demonstrating its excellent high-resolution imaging capability across the entire field of view.

[0045] Example 2: The optical system in Example 2 is as follows Figure 5 As shown, its optical path diagram is as follows: Figure 6 As shown, the relevant data for this optical system are presented in Tables 4 to 6: Table 4 Table 5 Table 6 Table 4 shows the imaging lens parameters of the laser displacement sensor in Example 2, Table 5 shows the focal length and object height of each lens, and Table 6 shows the ratio of the focal lengths of each lens.

[0046] In Example 2, the focal length of the imaging lens is 33.5mm, and the total length of the lens is 37.0mm.

[0047] Figure 7 The dot plot of the imaging lens in Example 2 shows that, at a working wavelength of 650 nm, the root mean square radius of the entire field of view is less than 4.2 μm. This indicates that the system has high energy concentration. Except for the maximum field of view, the root mean square radii of the remaining fields of view are all around 2 μm, indicating a very small measurement spot.

[0048] Figure 8 The MTF plot of the imaging lens in Example 2 shows that the modulation transfer function value is greater than 0.8 at the spatial frequency of 30 lp / mm across the entire field of view. At the Nyquist frequency of the detector (50 lp / mm), the MTF value across the entire field of view is greater than 0.7, indicating that it has good high-resolution imaging capability across the entire field of view.

[0049] In summary, the optical system of the large-aperture laser displacement sensor lens provided in this embodiment has an F-number of 2.85, which not only meets the requirements of strong light collection capability but also conforms to the current mainstream sensor size requirements; in addition, the lens has small aberrations, which can effectively present the image of the laser emission part; the high resolution results in fewer transition pixels of the light spot on the sensor, which greatly improves the detection accuracy of the displacement sensor.

[0050] Example 2: This embodiment provides a large-aperture laser displacement sensor imaging lens, including the optical system of a large-aperture laser displacement sensor imaging lens as described in Embodiment 1.

[0051] Since the optical system has been described in detail in Embodiment 1, it will not be repeated in this embodiment.

[0052] Furthermore, in practical applications, the physical installation position of the image plane (sensor) is often predetermined. To guide the light emitted from the lens to the designated position, a corresponding light-guiding device needs to be added in front of the image plane; for example... Figure 2 and Figure 6 As shown, a reflector G6 is also provided between the fifth lens G5 and the image plane. The placement angle of the reflector G6 is determined by the spatial position of the image plane and is used to reflect the light emitted from the fifth lens G5 to the image plane.

[0053] In summary, this embodiment 1, through the reasonable combination of multiple lenses, constructs an optical system that realizes a large-aperture laser displacement sensor imaging lens. This lens has good resolution and a small spot size, provides good imaging effect during measurement, and has the ability to converge scattered light from the surface of the measured object, enabling clear focusing of the light spot within the measurement range.

[0054] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical system for a large-aperture laser displacement sensor imaging lens, characterized in that, The system consists of a parallel protective glass plate G0 arranged sequentially from the object side to the image side, a first lens G1 with positive optical power, a second lens G2 with negative optical power, a third lens G3 with positive optical power, an aperture stop A0, a fourth lens G4 with negative optical power, and a fifth lens G5 with positive optical power; wherein, the second lens G2 and the third lens G3 form a cemented doublet lens U1. The optical system has a focal length of f', the first lens G1 has a focal length of f1, the second lens G2 has a focal length of f2, the third lens G3 has a focal length of f3, and the cemented doublet lens U1 has a focal length of f'. U1 The fourth lens G4 has a focal length of f4, and the fifth lens G5 has a focal length of f5, satisfying the following relationships: 1.0 ≤ |f1 / f'| ≤ 2.0, 0.1 ≤ |f2 / f'| ≤ 1.0, 0.1 ≤ |f3 / f'| ≤ 1.0, 4.0 ≤ |f U1 / f'|≤5.0, 2.0≤|f4 / f'|≤3.0, 0.1≤|f5 / f'|≤1.0。 2. The optical system of a large-aperture laser displacement sensor imaging lens according to claim 1, characterized in that, The first lens G1 has a refractive index of n1 and an Abbe number of v1, satisfying the following relationships: 1.9≤n1≤2.0; 30≤v1≤40; The refractive index of the second lens G2 is n2, and the Abbe number is v2, satisfying the following relationships: 1.7≤n2≤1.8; 20≤v2≤30; The refractive index of the third lens G3 is n3, and the Abbe number is v3, satisfying the following relationships: 1.8≤n3≤1.9; 40≤v3≤50; The fourth lens G4 has a refractive index of n4 and an Abbe number of v4, satisfying the following relationships: 1.5≤n4≤1.6; 50≤v4≤60; The fifth lens G5 has a refractive index of n5 and an Abbe number of v5, satisfying the following relationships: 1.8≤n5≤1.9; 40≤v5≤50.

3. The optical system of a large-aperture laser displacement sensor imaging lens according to claim 2, characterized in that, The first lens G1, the third lens G3, and the fifth lens G5 are all biconvex lenses, the second lens G2 is a biconcave lens, and the fourth lens G4 is a meniscus lens, with the convex surface of the fourth lens G4 facing the object side.

4. The optical system of a large-aperture laser displacement sensor imaging lens according to claim 3, characterized in that, The first lens G1, the second lens G2, the third lens G3, the fourth lens G4, and the fifth lens G5 are all glass spherical lenses, and the optical axes of all the glass spherical lenses coincide.

5. The optical system of a large-aperture laser displacement sensor imaging lens according to claim 4, characterized in that, The object height of the optical system is y', which satisfies the relationship: |y' / f'|≤1.

0.

6. The optical system of a large-aperture laser displacement sensor imaging lens according to claim 5, characterized in that, The optical system has an F-number of 2.85, a working distance of 90 mm, and a measurement range of ±15.6 mm after being adapted to the optical path of a laser displacement sensor.

7. The optical system of a large-aperture laser displacement sensor imaging lens according to claim 1, characterized in that, The aperture of aperture A0 is a circular hole.

8. A large-aperture laser displacement sensor imaging lens, characterized in that, The optical system includes a large-aperture laser displacement sensor imaging lens as described in any one of claims 1-7.

9. The large-aperture laser displacement sensor imaging lens according to claim 8, characterized in that, A reflector G6 is also provided between the fifth lens G5 and the image plane; the placement angle of the reflector G6 is determined by the spatial position of the image plane, and it is used to reflect the light emitted from the fifth lens G5 to the image plane.

Images