Industrial telecentric lens and optical system thereof

Abstract

The present invention relates to the technical field of machine vision lenses, and discloses an industrial telecentric lens and its optical system. The optical system comprises a front lens group S1 with positive focal power, a dichroic prism P, an aperture T, and a rear lens group S2 with positive focal power, which are arranged in sequence from the object side to the image side. The aperture T is arranged at the focus of the front lens group S1 to form an object-side telecentric structure; the front lens group S1 comprises a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with negative focal power, and a fourth lens G4 with positive focal power; the rear lens group S2 comprises a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, and a seventh lens G7 with positive focal power. The industrial telecentric lens and its optical system provided by the present invention have a working distance of 65 mm, a small external size, and good optical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of machine vision lenses, and in particular to an industrial telecentric lens and an optical system thereof. Background Art

[0002] In machine vision inspection systems, the use of ordinary industrial lenses will cause problems such as magnification changing with working distance, parallax, and large distortion, making it difficult to meet high-precision inspection requirements. Telecentric lenses can improve or even eliminate the above problems. Within a certain object distance range, the image magnification will not change with changes in object distance. Its principle advantages make it very suitable for the field of visual inspection.

[0003] In actual applications, the sizes and dimensions of objects that need to be measured in different application scenarios are different, and there are also many items to be inspected. Therefore, telecentric lenses of different specifications need to be designed to cope with them. In size-restricted inspection applications, the use of industrial telecentric lenses with short working distances and small dimensions is conducive to reducing the size of the mechanism and achieving miniaturization. The current mainstream short working distance industrial telecentric lenses on the market have a working distance of 65mm. This type of telecentric lens has problems such as small aperture, low resolution, and insufficient target surface. As the system's requirements for imaging performance continue to increase, there is an urgent need for short working distance industrial telecentric lenses with better imaging performance and larger target surface.

[0004] The above information is presented as background information only to assist with an understanding of the present disclosure and is not a determination or admission that any of the above may be applicable as prior art with respect to the present disclosure. Summary of the Invention

[0005] The object of the present invention is to provide an industrial telecentric lens and an optical system thereof, so as to solve or at least partially solve the technical problems existing in the prior art.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an optical system of an industrial telecentric lens, comprising a front lens group S1 with positive focal power, a beam splitter prism P, an aperture T, and a rear lens group S2 with positive focal power, arranged in sequence from the object side to the image side, wherein the aperture T is arranged at the focus of the front lens group S1, forming an object-side telecentric structure;

[0008] The front lens group S1 includes a first lens G1 with positive refractive power, a second lens G2 with positive refractive power, a third lens G3 with negative refractive power, and a fourth lens G4 with positive refractive power. The second lens G2 and the third lens G3 form a cemented lens U1 with negative refractive power. The rear lens group S2 includes a fifth lens G5 with negative refractive power, a sixth lens G6 with positive refractive power, and a seventh lens G7 with positive refractive power.

[0009] Among them, the combined focal length of the front S1 lens group is f S1 The combined focal length of the rear S2 lens group is smaller than f S2 .

[0010] Optionally, the first lens G1 and the second lens G2 are both biconvex lenses, the third lens G3 is a biconcave lens; and the fourth lens G4 is a meniscus lens or a biconvex lens.

[0011] The focal length of the first lens G1 is f1, and f1 and f S1 Satisfies the following relationship: 1.3<|f1 / f S1 |<1.9;

[0012] The focal length of the cemented lens U1 is f U1 , f U1 With f S1 Satisfies the relationship: 2<|f U1 / f S1 |<8;

[0013] The focal length of the fourth lens G4 is f4, and f4 is equal to f S1 Satisfies the following relationship: 0.8<|f 4 / f S1 |<1.25.

[0014] Optionally, the second lens G2 and the fourth lens G4 are made of crown glass.

[0015] Optionally, the focal length of the fifth lens G5 is f5, and f5 is equal to f S2 Satisfies the relationship: 0.18<|f5 / f S2 |<0.4;

[0016] The focal length of the seventh lens G7 is f7;

[0017] The sixth lens G6 is a meniscus lens, and the focal length of the sixth lens G6 is f6. S2 Satisfies the relationship: 0.8<|f6 / f S2 |<1.2, f7 and f6 satisfy the relationship: 0.8<|f7 / f6|<1.2; or, the sixth lens G6 includes a lens G61 with negative focal power and a lens G62 with positive focal power, and the lens G61 and the lens G62 are cemented together to form a cemented lens U2 with positive focal power, f U2 With f S2 Satisfies the relationship: 0.8<|f U2 / f S2 |<1.2, f7 and f U2 Satisfies the relationship: 0.8<|f7 / f U2 |<1.2.

[0018] Optionally, f S1 and f S2 Satisfies the relationship: 0.5<|f S1 / f S2 |<1.

[0019] Optionally, the optical axes of all lenses of the front lens group S1 and the rear lens group S2 coincide with the predetermined optical axis.

[0020] Optionally, the working distance of the optical system is WD, the on-axis distance from the first lens G1 to the image plane is TTL (Total Track Length, total length of the lens), and WD and TTL satisfy the relationship: WD / TTL<0.4.

[0021] Optionally, the half-image height y' of the optical system satisfies the relationship: y'<9.5 mm.

[0022] Optionally, the aperture of the diaphragm T is a circular hole, and the center of the circular hole is on the predetermined optical axis.

[0023] In a second aspect, the present invention provides an industrial telecentric lens, including an optical system of the industrial telecentric lens as described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides an industrial telecentric lens and an optical system thereof, which have a working distance of 65 mm and a small external size, have good optical performance, and support mainstream 10 million pixel 1.1-inch target surface cameras.

[0026] The present invention has other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and the following detailed description incorporated herein, which together serve to explain certain principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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.

[0028] Figure 1 The figure is a schematic structural diagram of an optical system of an industrial telecentric lens provided by an embodiment of the present invention.

[0029] Figure 2The figure is an object-space MTF curve diagram of an optical system of an industrial telecentric lens provided by an embodiment of the present invention.

[0030] Figure 3 This is an optical distortion curve of an optical system of an industrial telecentric lens provided by an embodiment of the present invention.

[0031] Figure 4 It is a structural schematic diagram of an optical system of another industrial telecentric lens provided by an embodiment of the present invention.

[0032] Figure 5 This is an object-space MTF curve diagram of an optical system of another industrial telecentric lens provided by an embodiment of the present invention.

[0033] Figure 6 This is an optical distortion curve of an optical system of another industrial telecentric lens provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to explain in detail the possible application scenarios, technical principles, specific solutions that can be implemented, and the purpose and effects of this application, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0035] References to "embodiments" herein mean that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the word "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the various technical features mentioned in the embodiments can be combined in any manner to form a corresponding implementable technical solution.

[0036] Unless otherwise defined, the technical terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0037] In the description of this application, the term "and / or" is used to describe a logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and both A and B exist. In addition, the character " / " in this document generally indicates that the objects before and after are in a logical "or" relationship.

[0038] In this application, terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, priority or sequence relationship between these entities or operations.

[0039] Without further limitations, in this application, the words "include", "comprise", "have" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those defined elements, but also other elements not explicitly listed, or elements inherent to such process, method or product.

[0040] Consistent with the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceed" are understood to exclude the number itself; expressions such as "above," "below," and "within" are understood to include the number itself. Furthermore, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this manner, such as "multiple groups," "multiple times," etc., unless otherwise specifically defined.

[0041] In the description of the embodiments of the present application, the space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating 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, it should not be understood as a limitation on the embodiments of the present application.

[0042] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms "installed", "connected", "connected", "fixed", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated 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 elements or the interaction relationship between two elements. For those skilled in the art of the present application, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0043] Example 1:

[0044] See also Figure 1 , Figure 1 The figure is a schematic structural diagram of an optical system of an industrial telecentric lens provided by an embodiment of the present invention.

[0045] like Figure 1 As shown, the optical system includes a front lens group S1 with positive focal length, a dichroic prism P, an aperture T, and a rear lens group S2 with positive focal length, which are arranged in sequence from the object side to the image side. The aperture T is set at the focus of the front lens group S1 to form an object-side telecentric structure. The combined focal length f of the front lens group S1 is S1 The combined focal length of the rear S2 lens group is smaller than f S2 .

[0046] Since the beam splitter prism P is disposed between the fourth lens element G4 and the aperture T, a coaxial illumination light source or other imaging system can be introduced through the beam splitter prism P.

[0047] Specifically, the front lens group S1 includes a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with negative focal power, and a fourth lens G4 with positive focal power. The second lens G2 and the third lens G3 form a cemented lens U1 with negative focal power; the rear lens group S2 includes a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, and a seventh lens G7 with positive focal power.

[0048] By satisfying the above relationship, the deflection and refraction capabilities of the front and rear groups can be reasonably distributed, and the overall dimensions of the optical system can be reduced.

[0049] Furthermore, the first lens G1 and the second lens G2 are both biconvex lenses, the third lens G3 is a biconcave lens; and the fourth lens G4 is a meniscus lens or a biconvex lens.

[0050] The focal length of the first lens G1 is f1, and f1 and f S1 Satisfies the following relationship: 1.3<|f1 / f S1 |<1.9;

[0051] The focal length of the doublet lens U1 is f U1 , f U1 With f S1 Satisfies the relationship: 2<|f U1 / f S1 |<8;

[0052] The focal length of the fourth lens G4 is f4, and f4 is equal to f S1 Satisfies the following relationship: 0.8<|f 4 / f S1 |<1.25.

[0053] As a preferred embodiment, the second lens G2 is made of crown glass, which is conducive to correcting system chromatic aberration; the fourth lens G4 is made of crown glass, which is conducive to reducing chromatic aberration and correcting spherical aberration.

[0054] Furthermore, the focal length of the fifth lens G5 is f5, and f5 is equal to f S2 Satisfies the relationship: 0.18<|f5 / f S2 |<0.4;

[0055] The focal length of the seventh lens G7 is f7, and f7 and f6 satisfy the relationship: 0.8<|f7 / f6|<1.2;

[0056] The sixth lens G6 is a meniscus lens, and the focal length of the sixth lens G6 is f6. S2 Satisfies the relationship: 0.8<|f6 / f S2 |<1.2; Its meniscus structure can improve the system's ability to correct astigmatism and field curvature, while also helping to reduce the system's overall dimensions;

[0057] In this embodiment, f S1 and f S2 Satisfies the relationship: 0.5<|f S1 / f S2 |<1.

[0058] It should be noted that, in this embodiment, the optical axes of all lenses of the front lens group S1 and the rear lens group S2 coincide with the predetermined optical axis.

[0059] Assume that the working distance of the optical system is WD (Working Distance), the on-axis distance from the first lens G1 to the image plane is TTL (Total Track Length), and WD and TTL satisfy the relationship: WD / TTL<0.4.

[0060] The half-image height y' of the optical system satisfies the relationship: y'<9.5mm.

[0061] For example, in this example, the relevant data of the optical system are shown in Table 1:

[0062] Table 1

[0063]

[0064]

[0065] It should be noted that in Table 1, the “front surface” corresponds to Figure 1 The left side surface of the lens or lens group corresponds to the "back surface" Figure 1The right side surface of the corresponding lens or lens group; or it can be understood as: the object side is Figure 1 On the left, the image side (or image plane) is Figure 1 On the right, the surface closer to the object side is the "front surface" and the surface closer to the image side is the "back surface".

[0066] In this example, the combined focal length of the front group S1 is f S1 =42mm; the combined focal length of the rear group S2 is f S2 =49mm; the focal length of the first lens G1 is f1 = 68mm; the focal length of the cemented lens group U1 is f U1 = -238mm; the focal length of the fourth lens G4 is f4 = 45mm; the focal length of the fifth lens G5 is f5 = -14mm; the focal length of the sixth lens G6 is f6 = 38mm; and the focal length of the seventh lens G7 is f7 = 39mm. Substituting the above values ​​into the respective equations, we obtain: |f1 / f S1 |=1.62,|f U1 / f S1 |=5.67,|f 4 / f S1 |=1.07,|f5 / f S2 |=0.29, |f7 / f6|=1.03, |f S1 / f S2 |=0.86; all satisfy the above relationship;

[0067] Please refer to Figure 2 and Figure 3 , Figure 2 : is an object-space MTF curve diagram of an optical system of an industrial telecentric lens provided by an embodiment of the present invention, Figure 3 is an optical distortion curve of an optical system of an industrial telecentric lens provided by an embodiment of the present invention; the optical parameters of the optical system are shown in Table 2 below:

[0068] Table 2

[0069]

[0070]

[0071] According to experimental verification, this embodiment realizes an optical system with an industrial telecentric lens having a focal length and a working distance of 65 mm through the structural design of the above-mentioned optical system. The maximum optical distortion of the entire field of view is less than 0.1%, and it has the characteristics of a large aperture and a compact structure, and has good optical performance.

[0072] Example 2:

[0073] See also Figure 4 , Figure 4It is a structural schematic diagram of an optical system of another industrial telecentric lens provided by an embodiment of the present invention.

[0074] like Figure 4 As shown, the optical system includes a front lens group S1 with positive focal length, a dichroic prism P, an aperture T, and a rear lens group S2 with positive focal length, which are arranged in sequence from the object side to the image side. The aperture T is set at the focus of the front lens group S1 to form an object-side telecentric structure. The combined focal length f of the front lens group S1 is S1 The combined focal length of the rear S2 lens group is smaller than f S2 .

[0075] Since the beam splitter prism P is disposed between the fourth lens element G4 and the aperture T, a coaxial illumination light source or other imaging system can be introduced through the beam splitter prism P.

[0076] Specifically, the front lens group S1 includes a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with negative focal power, and a fourth lens G4 with positive focal power. The second lens G2 and the third lens G3 form a cemented lens U1 with negative focal power; the rear lens group S2 includes a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, and a seventh lens G7 with positive focal power.

[0077] By satisfying the above relationship, the deflection and refraction capabilities of the front and rear groups can be reasonably distributed, thereby reducing the overall dimensions of the optical system.

[0078] Furthermore, the first lens G1 and the second lens G2 are both biconvex lenses, the third lens G3 is a biconcave lens; and the fourth lens G4 is a meniscus lens or a biconvex lens.

[0079] The focal length of the first lens G1 is f1, and f1 and f S1 Satisfies the following relationship: 1.3<|f1 / f S1 |<1.9;

[0080] The focal length of the cemented lens U1 is f U1 , f U1 With f S1 Satisfies the relationship: 2<|f U1 / f S1 |<8;

[0081] The focal length of the fourth lens G4 is f4, and f4 is equal to f S1 Satisfies the following relationship: 0.8<|f 4 / f S1 |<1.25.

[0082] As a preferred embodiment, the second lens G2 is made of crown glass, which is conducive to correcting system chromatic aberration; the fourth lens G4 is made of crown glass, which is conducive to reducing chromatic aberration and correcting spherical aberration.

[0083] Furthermore, the focal length of the fifth lens G5 is f5, and f5 is equal to f S2 Satisfies the relationship: 0.18<|f5 / f S2 |<0.4;

[0084] The sixth lens G6 includes a lens G61 with negative refractive power and a lens G62 with positive refractive power. The lens G61 and the lens G62 are cemented together to form a cemented lens U2 with positive refractive power. U2 With f S2 Satisfies the relationship: 0.8<|f U2 / f S2 |<1.2; Compared with the meniscus structure, the doublet lens structure can further improve the system's ability to correct astigmatism and field curvature. At the same time, the lens surface has a higher degree of freedom, which can better improve the system's imaging performance;

[0085] The focal length of the seventh lens G7 is f7, and f7 is equal to f U2 Satisfies the relationship: 0.8<|f7 / f U2 |<1.2.

[0086] In this embodiment, f S1 and f S2 Satisfies the relationship: 0.5<|f S1 / f S2 |<1.

[0087] It should be noted that, in this embodiment, the optical axes of all lenses of the front lens group S1 and the rear lens group S2 coincide with the predetermined optical axis.

[0088] Assume that the working distance of the optical system is WD, the on-axis distance from the first lens G1 to the image plane is TTL, and WD and TTL satisfy the relationship: WD / TTL<0.4.

[0089] The half-image height y' of the optical system satisfies the relationship: y'<9.5mm.

[0090] For example, in this example, the relevant data of the optical system are shown in Table 3:

[0091] Table 3

[0092]

[0093]

[0094] It should be noted that in Table 3, the “front surface” corresponds to Figure 4 The left side surface of the lens or lens group corresponds to the "back surface" Figure 4 The right side surface of the corresponding lens or lens group; or it can be understood as: the object side is Figure 4 On the left, the image side (or image plane) is Figure 4 On the right, the surface closer to the object side is the "front surface" and the surface closer to the image side is the "back surface".

[0095] In this example, the combined focal length of the front group S1 is f S1 =40mm; the combined focal length of the rear group S2 is f S2 =65mm; the focal length of the first lens G1 is f1 = 59mm; the focal length of the cemented lens group U1 is f U1 = -114mm; the focal length of the fourth lens G4 is f4 = 40mm; the focal length of the fifth lens G5 is f5 = -15mm; the focal length of the sixth lens G6 of the cemented structure is f U2 =42mm; the focal length of the seventh lens G7 is f7 = 43mm. Substituting the above values ​​into the respective equations, we obtain: |f1 / f S1 |=1.48,|f U1 / f S1 |=2.85,|f 4 / f S1 |=1,|f5 / f S2 |=0.23,|f7 / f U2 |=1.02,|f S1 / f S2 |=0.65; all satisfy the above relationship;

[0096] Please refer to Figure 5 and Figure 6 , Figure 5 : is an object-space MTF curve diagram of an optical system of another industrial telecentric lens provided by an embodiment of the present invention, Figure 6 This is an optical distortion curve of another optical system of an industrial telecentric lens provided by an embodiment of the present invention; the optical parameters of the optical system are shown in Table 4 below:

[0097] Table 4

[0098]

[0099]

[0100] According to experimental verification, this embodiment realizes an optical system with an industrial telecentric lens having a focal length and a working distance of 65 mm through the structural design of the above-mentioned optical system. The maximum optical distortion of the entire field of view is less than 0.1%, and it has the characteristics of a large aperture and a compact structure, and has good optical performance.

[0101] Example 3:

[0102] This embodiment provides an industrial telecentric lens, which adopts the optical system of the industrial telecentric lens described in the first or second embodiment.

[0103] Since the optical system has been described in detail in the above embodiment, it will not be described again in this embodiment.

[0104] In summary, the embodiment of the present invention realizes an industrial telecentric lens with a working distance of 65mm, a maximum optical distortion of less than 0.1% in the entire field of view, a large aperture and a compact structure, good optical performance, and supports mainstream 10 million pixel 1.1-inch target surface cameras.

[0105] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical system of an industrial telecentric lens, characterized in that: The optical system comprises a front lens group S1 with positive focal length, a dichroic prism P, a stop T, and a rear lens group S2 with positive focal length, which are arranged in sequence from the object side to the image side. The stop T is arranged at the focus of the front lens group S1 to form an object-side telecentric structure. The optical system has two lens groups, wherein the combined focal length f of the front lens group S1 is S1 The combined focal length of the rear S2 lens group is smaller than f S2 ; The front lens group S1 includes a first lens G1 with positive refractive power, a second lens G2 with positive refractive power, a third lens G3 with negative refractive power, and a fourth lens G4 with positive refractive power. The second lens G2 and the third lens G3 form a cemented lens U1 with negative refractive power. The rear lens group S2 includes a fifth lens G5 with negative refractive power, a sixth lens G6 with positive refractive power, and a seventh lens G7 with positive refractive power. The first lens G1 and the second lens G2 are both biconvex lenses, the third lens G3 is a biconcave lens; the fourth lens G4 is a meniscus lens or a biconvex lens; The focal length of the first lens G1 is f1, and f1 and f S1 Satisfies the following relationship: 1.3<|f1 / f S1 |<1.9; The focal length of the cemented lens U1 is f U1 , f U1 With f S1 Satisfies the relationship: 2<|f U1 / f S1 |<8; The focal length of the fourth lens G4 is f4, and f4 is equal to f S1 Satisfies the following relationship: 0.8<|f 4 / f S1 |<1.

25.

2. The optical system of an industrial telecentric lens according to claim 1, characterized in that: The second lens G2 and the fourth lens G4 are made of crown glass.

3. The optical system of an industrial telecentric lens according to claim 1, characterized in that: The focal length of the fifth lens G5 is f5, and f5 is equal to f S2 Satisfies the relationship: 0.18<|f5 / f S2 |<0.4; The focal length of the seventh lens G7 is f7; The sixth lens G6 is a meniscus lens, and the focal length of the sixth lens G6 is f6. S2 Satisfies the relationship: 0.8<|f6 / f S2 |<1.2, f7 and f6 satisfy the relationship: 0.8<|f7 / f6|<1.2; or, the sixth lens G6 includes a lens G61 with negative focal power and a lens G62 with positive focal power, and the lens G61 and the lens G62 are cemented together to form a cemented lens U2 with positive focal power, and the focal length of the cemented lens U2 is f U2 , f U2 With f S2 Satisfies the relationship: 0.8<|f U2 / f S2 |<1.2, f7 and f U2 Satisfies the relationship: 0.8<|f7 / f U2 |<1.

2.

4. The optical system of an industrial telecentric lens according to claim 3, characterized in that: f S1 and f S2 Satisfies the relationship: 0.5<|f S1 / f S2 |<1.

5. The optical system of an industrial telecentric lens according to claim 1, characterized in that: The optical axes of all lenses of the front lens group S1 and the rear lens group S2 coincide with the predetermined optical axis.

6. The optical system of an industrial telecentric lens according to claim 5, characterized in that: The working distance of the optical system is WD, the on-axis distance from the first lens G1 to the image plane is TTL, and WD and TTL satisfy the relationship: WD / TTL < 0.

4.

7. The optical system of an industrial telecentric lens according to claim 6, characterized in that: The half-image height y' of the optical system satisfies the relationship: y'<9.5 mm.

8. The optical system of an industrial telecentric lens according to claim 5, characterized in that: The aperture of the diaphragm T is a circular hole, and the center of the circular hole is on the predetermined optical axis.

9. An industrial telecentric lens, characterized in that: An optical system comprising an industrial telecentric lens as claimed in any one of claims 1 to 8.

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