Multi-angle inner wall detection lens device and optical system thereof

Abstract

The application relates to the technical field of optical imaging, and discloses a lens device for multi-angle inner wall detection and an optical system thereof. The optical system comprises a reflection assembly T1 and an imaging lens group T2 arranged in sequence from an object side to an image side; the reflection assembly T1 comprises a first mirror group M1 and a second mirror group M2; the included angle between incident light of the reflection assembly T1 and the optical axis of the imaging lens group T2 is alpha, the included angle between the first mirror group M1 and the optical axis of the imaging lens group T2 is beta1, the included angle between the second mirror group M2 and the optical axis of the imaging lens group is beta2, alpha, beta1 and beta2 satisfy the following relationship: 10 DEG <= alpha <= 60 DEG, 15 DEG <= beta2 <= 40 DEG, and alpha = 2*beta2-2*beta1. Through the structural design of the optical system, multi-angle optical imaging of the inner wall of a cylindrical product or a cavity workpiece is realized, six-angle images can be obtained through single shooting, the condition of the entire inner wall is completely presented, and space and cost are greatly saved.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a lens device and optical system for multi-angle inner wall detection. Background Technology

[0002] With the rapid development of the microelectronics industry, high-resolution, high-speed machine vision systems are constantly emerging, with an increasing application in the inspection of the inner walls of cylindrical products or cavity workpieces. Inner wall inspection generally requires accurate identification of internal defects such as cracks, scratches, and dirt. Specially designed high-resolution imaging is key to improving inspection accuracy, which places new demands on optical lenses. Conventional machine vision lenses can only image in a planar plane. To obtain complete information about the inner wall of cylindrical products or cavity workpieces, the lens needs to be angled towards one side of the inner wall to acquire an image, and then the workpiece needs to be rotated to capture the image on the other side. This inspection method is time-consuming, involves complex assembly, and results in incomplete inner wall inspection.

[0003] In order to reduce shooting space and shooting costs, there is an urgent need for a machine vision lens that can shoot the bottom of the inner hole and the vertical inner wall of an object from multiple perspectives.

[0004] 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

[0005] The purpose of this invention is to provide a lens device and optical system for multi-angle inner wall detection, so as to solve or at least partially solve the technical problems existing in the prior art.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an optical system for a lens device for multi-angle inner wall detection, comprising a reflective component T1 and an imaging lens group T2 arranged sequentially from the object side to the image side;

[0008] The reflective assembly T1 includes a first reflector group M1 and a second reflector group M2, and a ring light source S0 is provided between the first reflector group M1 and the second reflector group M2.

[0009] The angle between the incident ray from the reflecting component T1 and the optical axis of the imaging lens group T2 is α, the angle between the optical axis of the first reflecting mirror group M1 and the optical axis of the imaging lens group T2 is β1, and the angle between the optical axis of the second reflecting mirror group M2 and the optical axis of the imaging lens group is β2. α, β1, and β2 satisfy the following relationship:

[0010] 10°≤α≤60°, 15°≤β2≤40°, α=2*β2-2*β1.

[0011] Optionally, the imaging lens group T2 includes a front group L1 with positive optical power, an aperture A0, and a rear group L2 with positive optical power arranged sequentially from the object side to the image side.

[0012] The front group L1 includes a first lens G1 with positive optical power, a second lens G2 with positive optical power, and a third lens G3 with negative optical power arranged sequentially from the object side to the image side. The second lens G2 and the third lens G3 are cemented together to form a first cemented lens group U1 with positive optical power.

[0013] The rear group L2 includes a fourth lens G4 with negative optical power, a fifth lens G5 with positive optical power, and a sixth lens G6 with positive optical power. The fourth lens G4 and the fifth lens G5 are cemented together to form a second cemented lens group U2 with negative optical power.

[0014] Optionally, the focal length of the first lens G1 is f. G1 The focal length of the front group L1 is f L1 f G1 with f L1 Satisfies the relation: 1.20 < |f G1 / f L1 | < 1.90;

[0015] The focal length of the sixth lens G6 is f G6 The focal length of the rear L2 group is f. L2 f G6 with f L2 Satisfies the relation: 0.70 < |f G6 / f L2 | < 1.25.

[0016] Optionally, the Abbe number of the second lens G2 is V2, and the Abbe number of the third lens G3 is V3. V2 and V3 satisfy the relationship: 10 < |V2-V3| < 45.

[0017] The Abbe number of the fourth lens G4 is V4, and the Abbe number of the fifth lens G5 is V5. V4 and V5 satisfy the relationship: 25 < |V4-V5| < 55.

[0018] Optionally, the first lens G1, the second lens G2, the fifth lens G5 and the sixth lens G6 are all biconvex lenses, and the third lens G3 and the fourth lens G4 are both biconcave lenses.

[0019] Optionally, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6 and the sixth lens G6 are all glass spherical lenses.

[0020] Optionally, the first lens G1 is made of heavy phosphorus crown glass, the second lens G2 is made of fluorine crown glass, the third lens G3 is made of lanthanum flint glass, the fourth lens G4 is made of heavy flint glass, the fifth lens G6 is made of heavy phosphorus crown glass, and the sixth lens G6 is made of heavy lanthanum flint glass.

[0021] Optionally, the first mirror group M1 includes six rectangular first plane mirrors evenly distributed around the optical axis; the second mirror group M2 includes six isosceles trapezoidal second plane mirrors evenly distributed around the optical axis, each used in a one-to-one correspondence with the six first plane mirrors.

[0022] The side of the second planar reflector furthest from the first lens G1 is a narrower base of an isosceles trapezoid, and the narrower base is positioned close to the optical axis of the imaging lens group T2.

[0023] Optionally, the optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 all coincide with the optical axis of the imaging lens group T2;

[0024] The aperture of stop A0 is a circular aperture, and the center of the circular aperture is on the optical axis of the imaging lens group T2.

[0025] Secondly, the present invention provides a lens device for multi-angle inner wall detection, including the optical system of the lens device for multi-angle inner wall detection as described above.

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

[0027] This invention, through the aforementioned optical system, enables multi-angle optical imaging of the inner wall of cylindrical products or cavity workpieces. Six-angle images can be obtained in a single shot, fully presenting the condition of the entire inner wall, greatly saving space and cost.

[0028] 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

[0029] 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.

[0030] Figure 1 This is a schematic diagram of the optical system of a lens device for multi-angle inner wall detection provided in Embodiment 1 of the present invention.

[0031] Figure 2 The optical path diagram is provided for the optical system of a lens device for multi-angle inner wall detection according to Embodiment 1 of the present invention.

[0032] Figure 3 A diagram of a reflective component with β1 = 0° provided for an embodiment of the present invention.

[0033] Figure 4 A diagram of another reflective component with β1 = 10° provided for an embodiment of the present invention.

[0034] Figure 5 The MTF transfer function curve of the optical system of a lens device for multi-angle inner wall detection provided in an embodiment of the present invention.

[0035] Figure 6 An imaging image of the inner wall of a cylindrical product provided in an embodiment of the present invention. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Similar to the understanding 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.

[0043] 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.

[0044] 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.

[0045] Example 1:

[0046] Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the optical system of a lens device for multi-angle inner wall detection provided in Embodiment 1 of the present invention. Figure 2 The optical path diagram is provided for the optical system of a lens device for multi-angle inner wall detection according to Embodiment 1 of the present invention.

[0047] like Figure 1 or Figure 2 As shown, the optical system includes:

[0048] The reflective component T1 and the imaging lens group T2 are arranged sequentially from the object side to the image side;

[0049] The reflective assembly T1 includes a first reflector group M1 and a second reflector group M2, and a ring light source S0 is provided between the first reflector group M1 and the second reflector group M2.

[0050] For better understanding, please refer to... Figure 3 or Figure 4 , Figure 3 This is a diagram of a reflective component with β1 = 0° provided in an embodiment of the present invention. Figure 4 A diagram of another reflective component with β1 = 10° provided for an embodiment of the present invention;

[0051] like Figure 3 As shown, the angle between the incident ray from the reflecting component T1 and the optical axis of the imaging lens group T2 is set as α, as follows: Figure 4 As shown, the optical axis angle between the first reflecting mirror group M1 and the imaging lens group T2 is set to β1, and the optical axis angle between the second reflecting mirror group M2 and the imaging lens group is set to β2.

[0052] In this embodiment, α, β1, and β2 satisfy the following relationship:

[0053] 10°≤α≤60°, 15°≤β2≤40°, α=2*β2-2*β1.

[0054] Specifically, in this embodiment, the first reflector group M1 includes six rectangular first plane reflectors evenly distributed around the optical axis; the second reflector group M2 includes six isosceles trapezoidal second plane reflectors evenly distributed around the optical axis, each used in a one-to-one correspondence with the six first plane reflectors.

[0055] The side of the second plane mirror furthest from the first lens G1 is a narrower base of an isosceles trapezoid, which is positioned close to the optical axis of the imaging lens group T2.

[0056] Specifically, the imaging lens group T2 includes a front group L1 with positive optical power, an aperture A0, and a rear group L2 with positive optical power, arranged sequentially from the object side to the image side.

[0057] The front group L1 includes a first lens G1 with positive optical power, a second lens G2 with positive optical power, and a third lens G3 with negative optical power arranged sequentially from the object side to the image side. The second lens G2 and the third lens G3 are cemented together to form a first cemented lens group U1 with positive optical power.

[0058] The rear group L2 includes a fourth lens G4 with negative optical power, a fifth lens G5 with positive optical power, and a sixth lens G6 with positive optical power. The fourth lens G4 and the fifth lens G5 are cemented together to form a second cemented lens group U2 with negative optical power.

[0059] Furthermore, the focal length of the first lens G1 is f. G1 The focal length of the front group L1 is f L1 f G1 with f L1 Satisfies the relation: 1.20 < |f G1 / f L1 | < 1.90;

[0060] The focal length of the sixth lens G6 is f G6 The focal length of the rear L2 group is f. L2 f G6 with f L2 Satisfies the relation: 0.70 < |f G6 / f L2 | < 1.25.

[0061] The Abbe number of the second lens G2 is V2, and the Abbe number of the third lens G3 is V3. V2 and V3 satisfy the relationship: 10 < |V2-V3| < 45.

[0062] The Abbe number of the fourth lens G4 is V4, and the Abbe number of the fifth lens G5 is V5. V4 and V5 satisfy the relationship: 25 < |V4-V5| < 55.

[0063] More specifically, the first lens G1, the second lens G2, the fifth lens G5 and the sixth lens G6 are all biconvex lenses, and the third lens G3 and the fourth lens G4 are both biconcave lenses.

[0064] The first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 are all glass spherical lenses.

[0065] As an optional implementation, in this embodiment, the first lens G1 is made of heavy phosphorus crown glass, the second lens G2 is made of fluorine crown glass, the third lens G3 is made of lanthanum flint glass, the fourth lens G4 is made of heavy flint glass, the fifth lens G6 is made of heavy phosphorus crown glass, and the sixth lens G6 is made of heavy lanthanum flint glass.

[0066] It should be noted that the optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 all coincide with the optical axis of the imaging lens group T2.

[0067] The aperture of stop A0 is a circular aperture, and the center of the circular aperture is on the optical axis of the imaging lens group T2.

[0068] Understandably, the aperture value of stop T needs to be adjusted according to the specific application scenario.

[0069] To verify whether the optical system described above meets the design objectives, the following are specific application examples based on the above settings in this embodiment:

[0070] In this application example, the lens data of the optical system are shown in Table 1 below:

[0071] Table 1

[0072] surface Radius (mm) Thickness (mm) Abbe number Angle with optical axis surface flat 25 Mirror M1 flat 37.6 0° Mirror M2 flat 51.4 17.5° G1 front surface 75.7 4.4 64.5 G1 rear surface -164.2 42.3 U1 front surface 18.4 4.4 81 U1 Adhesive Surface -107.4 7.6 47 U1 rear surface 46.7 21.5 Aperture flat 6.2 U2 front surface -10.3 9.9 23.5 U2 adhesive surface 28.8 10.0 64.5 U2 rear surface -20.5 1.9 G6 front surface 72.8 2.8 28 G6 rear surface -51.7 39.1 Image flat

[0073] It should be noted that in Table 1, "front surface" corresponds to... Figure 1 The left surface of the lens or lens group corresponds to the middle surface, while the rear surface corresponds to the left surface. Figure 1 The right side surface of the corresponding lens or lens group; or it can be understood as: the object surface in Figure 1 On the left, the image plane (or image surface) is... Figure 1 On the right side, the surface closer to the object is called the "front surface", and the surface closer to the image is called the "back surface".

[0074] In this application example, such as Figure 3 As shown, the angle α between the incident ray from the reflecting device T1 and the optical axis of the imaging lens group T2 is 35°, the angle β1 between the first reflecting mirror group M1 and the optical axis of the imaging lens group T2 is 0°, the angle β2 between the second reflecting mirror group M2 and the optical axis of the imaging lens group is 17.5°, and the focal length f of the front group L1 of the imaging lens group T2 is... L1 =54.63mm, focal length f of rear group L2 L2 =28.24mm, the focal length f of the first lens G1 G1 = 86.23mm, the focal length f of the sixth lens G6 G6 =30.25mm.

[0075] Various relational expressions:

[0076] α=35°; β1=0°; β2=17.5°;

[0077] |f G1 / f L1 |=1.58; |V2-V3|=34; |V4-V5|=41; |f G6 / f L2 |=1.07.

[0078] Satisfying the relation:

[0079] 10°≤α≤60°, 15°≤β2≤40°, α=2*β2-2*β1;

[0080] 1.20 < |f G1 / f L1 |<1.90;10<|V2-V3|<45;25<|V4-V5|<55;

[0081] 0.70 < |f G6 / f L2 | < 1.25.

[0082] Please refer to Figure 5 and Figure 6 , Figure 5 The MTF (Modulation Transfer Function) transfer function curve of the optical system of a lens device for multi-angle inner wall detection provided in this embodiment of the invention is shown. Figure 6 An imaging image of the inner wall of a cylindrical product provided in an embodiment of the present invention;

[0083] like Figure 6 As shown, the above structure enables multi-angle optical imaging of the inner wall of cylindrical products or cavity workpieces. Six images can be obtained from a single shot, fully presenting the entire inner wall and significantly saving space and cost. Figure 5 As shown, the lens device has a maximum resolution of 65 lp / mm and a maximum imaging circle of Φ10 mm.

[0084] Example 2:

[0085] This embodiment provides a lens device for multi-angle inner wall detection, including the optical system of a lens device for multi-angle inner wall detection as described in Embodiment 1.

[0086] like Figure 1 or Figure 2 As shown, the optical system includes:

[0087] The reflective component T1 and the imaging lens group T2 are arranged sequentially from the object side to the image side;

[0088] The reflective assembly T1 includes a first reflector group M1 and a second reflector group M2, and a ring light source S0 is provided between the first reflector group M1 and the second reflector group M2.

[0089] For better understanding, please refer to... Figure 3 or Figure 4 , Figure 3 This is a diagram of a reflective component with β1 = 0° provided in an embodiment of the present invention. Figure 4 A diagram of another reflective component with β1 = 10° provided for an embodiment of the present invention;

[0090] like Figure 3 As shown, the angle between the incident ray from the reflecting component T1 and the optical axis of the imaging lens group T2 is set as α, as follows: Figure 4 As shown, the optical axis angle between the first reflecting mirror group M1 and the imaging lens group T2 is set to β1, and the optical axis angle between the second reflecting mirror group M2 and the imaging lens group is set to β2.

[0091] In this embodiment, α, β1, and β2 satisfy the following relationship:

[0092] 10°≤α≤60°, 15°≤β2≤40°, α=2*β2-2*β1.

[0093] Specifically, in this embodiment, the first reflector group M1 includes six rectangular first plane reflectors evenly distributed around the optical axis; the second reflector group M2 includes six isosceles trapezoidal second plane reflectors evenly distributed around the optical axis, each used in a one-to-one correspondence with the six first plane reflectors.

[0094] The side of the second plane mirror furthest from the first lens G1 is a narrower base of an isosceles trapezoid, which is positioned close to the optical axis of the imaging lens group T2.

[0095] Specifically, the imaging lens group T2 includes a front group L1 with positive optical power, an aperture A0, and a rear group L2 with positive optical power, arranged sequentially from the object side to the image side.

[0096] The front group L1 includes a first lens G1 with positive optical power, a second lens G2 with positive optical power, and a third lens G3 with negative optical power arranged sequentially from the object side to the image side. The second lens G2 and the third lens G3 are cemented together to form a first cemented lens group U1 with positive optical power.

[0097] The rear group L2 includes a fourth lens G4 with negative optical power, a fifth lens G5 with positive optical power, and a sixth lens G6 with positive optical power. The fourth lens G4 and the fifth lens G5 are cemented together to form a second cemented lens group U2 with negative optical power.

[0098] Furthermore, the focal length of the first lens G1 is f. G1 The focal length of the front group L1 is f L1 f G1 with f L1 Satisfies the relation: 1.20 < |f G1 / f L1 | < 1.90;

[0099] The focal length of the sixth lens G6 is f G6 The focal length of the rear L2 group is f. L2 f G6 with f L2 Satisfies the relation: 0.70 < |f G6 / f L2 | < 1.25.

[0100] The Abbe number of the second lens G2 is V2, and the Abbe number of the third lens G3 is V3. V2 and V3 satisfy the relationship: 10 < |V2-V3| < 45.

[0101] The Abbe number of the fourth lens G4 is V4, and the Abbe number of the fifth lens G5 is V5. V4 and V5 satisfy the relationship: 25 < |V4-V5| < 55.

[0102] More specifically, the first lens G1, the second lens G2, the fifth lens G5 and the sixth lens G6 are all biconvex lenses, and the third lens G3 and the fourth lens G4 are both biconcave lenses.

[0103] The first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 are all glass spherical lenses.

[0104] As an optional implementation, in this embodiment, the first lens G1 is made of heavy phosphorus crown glass, the second lens G2 is made of fluorine crown glass, the third lens G3 is made of lanthanum flint glass, the fourth lens G4 is made of heavy flint glass, the fifth lens G6 is made of heavy phosphorus crown glass, and the sixth lens G6 is made of heavy lanthanum flint glass.

[0105] It should be noted that the optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 all coincide with the optical axis of the imaging lens group T2.

[0106] The aperture of stop A0 is a circular aperture, and the center of the circular aperture is on the optical axis of the imaging lens group T2.

[0107] Understandably, the aperture value of stop T needs to be adjusted according to the specific application scenario.

[0108] In summary, the angle α between the incident light and the optical axis of the imaging lens group T2 of this lens device ranges from 10° to 60°, enabling the detection of cylindrical products or cavity workpieces with an inner diameter of 1mm to 15mm. The ratio of depth to inner diameter that can be measured can range from 5.6:1 to 0.6:1. In addition, the reflective device contains a ring light source S0, and the integrated lighting design makes it more convenient to illuminate.

[0109] 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 lens device for multi-angle inner wall detection, characterized in that, It consists of a reflective component T1 and an imaging lens group T2 arranged sequentially from the object side to the image side; The reflective assembly T1 includes a first reflector group M1 and a second reflector group M2, and a ring light source S0 is provided between the first reflector group M1 and the second reflector group M2. The imaging lens group T2 consists of a front group L1 with positive optical power, an aperture A0, and a rear group L2 with positive optical power, arranged sequentially from the object side to the image side. The front group L1 consists of a first lens G1 with positive optical power, a second lens G2 with positive optical power, and a third lens G3 with negative optical power arranged sequentially from the object side to the image side. The second lens G2 and the third lens G3 are cemented together to form a first cemented lens group U1 with positive optical power. The rear group L2 consists of a fourth lens G4 with negative optical power, a fifth lens G5 with positive optical power, and a sixth lens G6 with positive optical power. The fourth lens G4 and the fifth lens G5 are cemented together to form a second cemented lens group U2 with negative optical power. The focal length of the first lens G1 is f G1 The focal length of the front group L1 is f L1 f G1 with f L1 Satisfies the relation: 1.20 < |f G1 / f L1 | < 1.90; The focal length of the sixth lens G6 is f G6 The focal length of the rear L2 group is f. L2 f G6 with f L2 Satisfies the relation: 0.70 < |f G6 / f L2 | < 1.25; The first reflector group M1 consists of six rectangular first plane reflectors evenly distributed around the optical axis; the second reflector group M2 consists of six isosceles trapezoidal second plane reflectors evenly distributed around the optical axis, each used in a one-to-one correspondence with the six first plane reflectors. The side of the second plane mirror away from the first lens G1 is a narrower base of an isosceles trapezoid, and the narrower base is positioned close to the optical axis of the imaging lens group T2. The angle between the incident ray from the reflecting component T1 and the optical axis of the imaging lens group T2 is α, the angle between the optical axis of the first reflecting mirror group M1 and the optical axis of the imaging lens group T2 is β1, and the angle between the optical axis of the second reflecting mirror group M2 and the optical axis of the imaging lens group is β2. α, β1, and β2 satisfy the following relationship: 10°≤α≤60°,15°≤β2≤40°,α＝2*β2-2*β1。 2. The optical system of the lens device for multi-angle inner wall detection according to claim 1, characterized in that, The Abbe number of the second lens G2 is V2, and the Abbe number of the third lens G3 is V3. V2 and V3 satisfy the relationship: 10 < |V2-V3| < 45. The Abbe number of the fourth lens G4 is V4, and the Abbe number of the fifth lens G5 is V5. V4 and V5 satisfy the relationship: 25 < |V4-V5| < 55.

3. The optical system of the lens device for multi-angle inner wall detection according to claim 1, characterized in that, The first lens G1, the second lens G2, the fifth lens G5, and the sixth lens G6 are all biconvex lenses, while the third lens G3 and the fourth lens G4 are both biconcave lenses.

4. The optical system of the lens device for multi-angle inner wall detection according to claim 3, characterized in that, The first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 are all glass spherical lenses.

5. The optical system of the lens device for multi-angle inner wall detection according to claim 4, characterized in that, The first lens G1 is made of heavy phosphorus crown glass, the second lens G2 is made of fluorine crown glass, the third lens G3 is made of lanthanum flint glass, the fourth lens G4 is made of heavy flint glass, the fifth lens G6 is made of heavy phosphorus crown glass, and the sixth lens G6 is made of heavy lanthanum flint glass.

6. The optical system of the lens device for multi-angle inner wall detection according to claim 1, characterized in that, The optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G6, and the sixth lens G6 all coincide with the optical axis of the imaging lens group T2. The aperture of stop A0 is a circular aperture, and the center of the circular aperture is on the optical axis of the imaging lens group T2.

7. A lens device for multi-angle inner wall detection, characterized in that, An optical system including a lens device for multi-angle inner wall detection as described in any one of claims 1-6.

Images