A 2.5 micron pixel camera and high resolution low distortion dual telecentric lens and optical system thereof

Abstract

The application relates to the technical field of machine vision lenses, and discloses a 2.5-micron-pixel camera and a high-resolution low-distortion double-telecentric lens and an optical system thereof. The optical system comprises, arranged in sequence from an object side to an image side, a first lens G1 with positive refractive power, a second lens G2 with positive refractive power, a third lens with positive refractive power, a fourth lens G4 with negative refractive power, a fifth lens G5 with negative refractive power, a sixth lens G6 with positive refractive power, a seventh lens G7 with positive refractive power, an eighth lens G8 with positive refractive power and a ninth lens G9 with negative refractive power, and the optical axes of all the lenses coincide with a predetermined optical axis. The application realizes a high-resolution low-distortion double-telecentric lens, the full-field distortion of which is less than 0.02%, and the resolution of which can reach 200 lp / mm, so that the measurement precision can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machine vision lenses, in particular to a 2.5-micron-pixel camera and a high-resolution low-distortion double-telecentric lens and an optical system thereof. BACKGROUND

[0002] In a machine vision precision optical measurement system, using ordinary industrial lenses can cause problems such as different magnification, parallax, large distortion, etc. due to changes in object distance, which is difficult to meet the high detection requirements. However, a telecentric lens can reduce or even eliminate the above problems. It can keep the image magnification constant within a certain object distance range. Its principle advantage makes it very suitable for precision measurement and detection fields. Telecentric lenses are widely used in the field of machine vision precision detection, such as product measurement and judgment, defect detection in the fields of semiconductors, 3C electronics, new energy, packaging and printing, intelligent logistics, automobile manufacturing, and pharmaceuticals.

[0003] With the continuous development of the machine vision industry and the continuous improvement of the resolution of camera chips, the technical requirements for telecentric lenses are also continuously improving. Lower distortion and higher resolution are a development direction for telecentric lenses. In order to meet market demand, it is urgent to design a double-telecentric lens that needs to have the characteristics of high resolution and low distortion, thereby improving the accuracy of measurement.

[0004] The above information is given as background information only to assist with an understanding of the present disclosure, and does not constitute admission or recognition that any of the above information constitutes prior art with respect to the present disclosure. SUMMARY

[0005] The purpose of the present application is to provide a 2.5-micron-pixel camera and a high-resolution low-distortion double-telecentric lens and an optical system thereof to solve or at least partially solve the technical problems existing in the prior art.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides an optical system of a high-resolution low-distortion double-telecentric lens, comprising a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with positive focal power, a fourth lens G4 with negative focal power, a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, a seventh lens G7 with positive focal power, an eighth lens G8 with positive focal power, and a ninth lens G9 with negative focal power, which are arranged in order from the object side to the image side, and the optical axes of all lenses coincide with the predetermined optical axis.

[0008] The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3.

[0009] The aperture stop S is located between the fourth lens G4 and the fifth lens G5; the light rays incident parallel to the first lens G1 are refracted by the second lens G2 and the cemented lens U1 and converge at the aperture stop S.

[0010] Optionally, the center distance between the front surface of the first lens G1 and the aperture stop S is L1, and the center distance between the aperture stop S and the image plane is L2.

[0011] The focal length f1 of the first lens G1 satisfies the following relationship: 0.9 < |f1 / L1| < 1.3;

[0012] The focal length f2 of the second lens G2 satisfies the following relationship: 0.8 < |f2 / L1| < 1.3;

[0013] The focal length f of the cemented lens group U1 U1 The relation is satisfied: 0.3 < |f U1 / L1|<0.6;

[0014] The focal length f of the cemented lens group U2 U2 The relation is satisfied: 0.5 < |f U2 / L2|<0.8;

[0015] The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35 < |f7 / L2| < 0.62;

[0016] The focal length f of the cemented lens group U3 U3 The relation is satisfied: 0.75 < |f U3 / L2|<1.05.

[0017] Optionally, the first lens G1 is a biconvex glass spherical lens, the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all meniscus glass spherical lenses, the fifth lens G5 is a biconcave glass spherical lens, and the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all biconvex glass spherical lenses.

[0018] Optionally, the refractive index of the third lens G3 is n3, and the Abbe number is v3, where n3 and v3 satisfy the following relationship: 1.47 <n3<60,65<v3<82。

[0019] Optionally, the refractive index of the eighth lens G8 is less than that of the ninth lens G9.

[0020] Optionally, the aperture of the stop S is a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0021] The aperture of the diaphragm is adjusted in the range of F4.8 to F32.

[0022] In a second aspect, the application provides a high-resolution low-distortion dual-telecentric lens, comprising an optical system of a high-resolution low-distortion dual-telecentric lens as described above.

[0023] In a third aspect, the application further provides a 2.5-micron-pixel camera equipped with a high-resolution low-distortion dual-telecentric lens as described above.

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

[0025] The optical system composed of the first lens G1 to the ninth lens G9 provided by the application realizes a high-resolution low-distortion dual-telecentric lens, the total field distortion of which is less than 0.02%, the distortion is extremely low, and the object can be measured almost without deformation; the resolution can reach 200 lp / mm, and the measurement accuracy can be effectively improved.

[0026] The application has other characteristics and advantages, which will be apparent or will be described in detail in the accompanying drawings and subsequent specific embodiments incorporated herein, which are collectively used to explain the specific principles of the application. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 is a structural schematic diagram of an optical system of a high-resolution low-distortion dual-telecentric lens provided by the embodiment of the application.

[0029] Figure 2 is a structural schematic diagram of an optical system of a high-resolution low-distortion dual-telecentric lens provided by the embodiment of the application when the working distance is 306 mm.

[0030] Figure 3 is an MTF curve diagram of an optical system of a high-resolution low-distortion dual-telecentric lens provided by the embodiment of the application when the working distance is 306 mm.

[0031] Figure 4is an optical distortion curve of the optical system of the high-resolution low-distortion dual-telecentric lens provided by the embodiment of the present application when the working distance is 306mm.

[0032] Figure 5 is a structural schematic diagram of the optical system of another high-resolution low-distortion dual-telecentric lens provided by the embodiment of the present application when the working distance is 312mm.

[0033] Figure 6 is an MTF curve diagram of the optical system of another high-resolution low-distortion dual-telecentric lens provided by the embodiment of the present application when the working distance is 312mm.

[0034] Figure 7 is an optical distortion curve of the optical system of another high-resolution low-distortion dual-telecentric lens provided by the embodiment of the present application when the working distance is 312mm. DETAILED DESCRIPTION

[0035] To make the possible application scenarios, technical principles, specific schemes that can be implemented, purposes and effects that can be achieved of the present application clear, the following will be described in detail in combination with the specific embodiments listed and the accompanying drawings. The embodiments described in the present text are only used to more clearly illustrate the technical schemes of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0036] In the present text, the term “embodiment” means that the specific features, structures or characteristics described in combination with the embodiment can be contained in at least one embodiment of the present application. The term “embodiment” appearing at various positions in the specification does not necessarily refer to the same embodiment, and does not particularly limit the independence or association between other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form a corresponding implementable technical scheme.

[0037] Unless otherwise defined, the meanings of the technical terms used in the present text are the same as those generally understood by the person skilled in the art to which the present application belongs; the use of related terms in the present text is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0038] In the description of the present application, the phrase “and / or” is a description of the logical relationship between the objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases: A exists, B exists, and A and B exist at the same time. In addition, the character “ / ” in the present text generally represents that the associated objects before and after are a “or” logical relationship.

[0039] In the present application, the 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 number, primary or secondary, or order relationship between the entities or operations.

[0040] In the present application, the "comprise", "include", "have" or other similar expressions used in the statements are intended to cover the non-exclusive inclusion, and the expressions do not exclude the presence of additional elements in the process, method or product comprising the elements, so that the process, method or product comprising a series of elements can not only include those defined elements, but also include other elements not explicitly listed, or also include the elements inherent to such process, method or product.

[0041] As the same understanding as in the "Guidelines for Examination", in the present application, the expressions such as "greater than", "less than", "exceed" are understood as not including the number; the expressions such as "above", "below", "within" are understood as including the number. In addition, in the description of the embodiments of the present application, the meaning of "multiple" is more than two (including two), and similar expressions related to "multiple" are also understood in this way, for example, "multiple groups", "multiple times" and the like, unless otherwise explicitly specified.

[0042] In the description of the embodiments of the present application, the spatial-related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. The indicated orientation or position relationship is based on the orientation or position relationship shown in the specific embodiment or the drawing, and is only for the convenience of describing the specific embodiments of the present application or for the reader to understand, and does not indicate or imply that the indicated device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0043] Unless otherwise explicitly specified or limited, in the description of the embodiments of the present application, the terms "mount", "connect", "connect", "fix", "set", etc. should be understood in a broad sense. For example, the "connection" can be a fixed connection, or a detachable connection, or an integral setting; it can be a mechanical connection, or an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art to which the present application belongs, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0044] Embodiment one:

[0045] Please refer to Figure 1 , Figure 1 is a high-resolution low-distortion double-telecentric lens optical system structure schematic diagram provided by the embodiment of the application.

[0046] As Figure 1 shown, the optical system includes first lens G1 with positive focal length, second lens G2 with positive focal length, third lens G3 with positive focal length, fourth lens G4 with negative focal length, fifth lens G5 with negative focal length, sixth lens G6 with positive focal length, seventh lens G7 with positive focal length, eighth lens G8 with positive focal length and ninth lens G9 with negative focal length arranged in order from object side to image side, and the optical axes of all lenses coincide with the predetermined optical axis;

[0047] The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3;

[0048] The stop S is arranged between the fourth lens G4 and the fifth lens G5; the light rays parallel incident to the first lens G1 converge at the stop S after being refracted by the second lens G2 and the cemented lens U1.

[0049] Further, the center distance between the front surface of the first lens G1 and the stop S is L1, and the center distance between the stop S and the image plane is L2;

[0050] The focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.3;

[0051] The first lens G1 converges the parallel incident light rays to the stop S, and by satisfying the above relationship, on the one hand, the height of the light rays can be quickly reduced, which is beneficial to reducing the system length size, and on the other hand, the lenses behind can be brought together to the stop position, thereby reducing the outer diameter size of the lenses.

[0052] Further, the focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3; the second lens G2 is away from the first lens G1 and close to the stop S side, which can maintain a small outer diameter size; as Figure 1 shown, the second lens G2 is a meniscus structure bending towards the stop, which can moderate the incident light ray angle and balance the spherical aberration and coma;

[0053] The focal length f U1 of the cemented lens group U1 satisfies the relationship: 0.3<|f U1|L1|<0.6; in this embodiment, the third lens G3 is made of low dispersion material, which can better correct chromatic aberration. Specifically, the third lens G3 has a refractive index n3 and an Abbe number v3, and n3 and v3 satisfy the following relationships: 1.47 < n3 < 60 and 65 < v3 < 82, respectively.

[0054] The focal length f of the cemented lens group U2 U2 The relationship 0.5 < |f U2 |L2| < 0.8; in this embodiment, the fifth lens G5 and the sixth lens G6 of the cemented lens group U2 are both made of high refractive index material, which can bear a large incident angle while maintaining a suitable shape to form small field curvature and spherical aberration.

[0055] The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35 < |f7 / L2| < 0.62;

[0056] The focal length f of the cemented lens group U3 U3 The relationship 0.75 < |f U3 |L2| < 1.05. In this embodiment, the eighth lens G8 has a refractive index n8 and the ninth lens G9 has a refractive index n9, and they satisfy the relationship n8 < n9. By satisfying the above relationship, the cemented surface of the cemented lens has negative focal power, which can balance the residual spherical aberration of the front lens, coma, and is also beneficial to the correction of distortion.

[0057] In this embodiment, the first lens G1 to the ninth lens G9 are all glass spherical lenses. Specifically, the first lens G1 is a double-convex glass spherical lens, the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all glass spherical lenses with a meniscus structure, the fifth lens G5 is a double-concave glass spherical lens, and the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all double-convex glass spherical lenses.

[0058] In this embodiment, the aperture of the diaphragm S is a circular hole, and the center of the circular hole is on the predetermined optical axis.

[0059] The aperture adjustment range of the diaphragm is F4.8~F32.

[0060] For example, based on the above design idea, an optical system is designed in this embodiment, as shown in Figure 2 The related data of the optical system is shown in Table 1 as follows:

[0061] Table 1

[0062] Surface Radius (mm) Thickness (mm) Refractive index Abbe number G1 front surface 409.8 24.4 1.70 25 G1 rear surface -827.0 247.9 G2 front surface 79.2 10.6 1.65 G2 rear surface 118.1 18.5 G3 front surface 28.5 13.9 1.50 80 G3, G4 cementing surface 95.4 10.3 1.80 G4 rear surface 21.9 25.9 Stop S ∞ 6.5 G5 front surface -8.2 1.3 1.95 G5, G6 cementing surface 75.9 5.5 1.80 G6 rear surface -12.3 0.1 G7 front surface 286.1 5.7 1.90 G7 rear surface -27.0 3.2 G8 front surface 56.3 7.7 1.95 G8, G9 cementing surface -19.3 8.5 2.0 25 G9 rear surface -188.6 18.9 Image surface /

[0063] It should be noted that in Table 1, the "front surface" corresponds to the Figure 2The "front surface" corresponds to the left surface of the corresponding lens or lens group, and the "back surface" corresponds to the right surface of the corresponding lens or lens group. Figure 2 The "front surface" corresponds to the left surface of the corresponding lens or lens group, and the "back surface" corresponds to the right surface of the corresponding lens or lens group. Figure 2 The "front surface" corresponds to the left surface of the corresponding lens or lens group, and the "back surface" corresponds to the right surface of the corresponding lens or lens group. Figure 1 The "front surface" corresponds to the left surface of the corresponding lens or lens group, and the "back surface" corresponds to the right surface of the corresponding lens or lens group.

[0064] In the optical system shown in the table, the distance L1=351mm, the distance L2=57mm, the focal length f1 of the first lens G1=391mm, the focal length f2 of the second lens G2=332mm, the focal length f of the cemented lens group U1=-158mm, the focal length f of the cemented lens group U2=-38mm, the focal length f of the cemented lens group U3=51mm, and the focal length f7 of the seventh lens G7=27mm. U1 In the optical system shown in the table, the distance L1=351mm, the distance L2=57mm, the focal length f1 of the first lens G1=391mm, the focal length f2 of the second lens G2=332mm, the focal length f of the cemented lens group U1=-158mm, the focal length f of the cemented lens group U2=-38mm, the focal length f of the cemented lens group U3=51mm, and the focal length f7 of the seventh lens G7=27mm. U2 In the optical system shown in the table, the distance L1=351mm, the distance L2=57mm, the focal length f1 of the first lens G1=391mm, the focal length f2 of the second lens G2=332mm, the focal length f of the cemented lens group U1=-158mm, the focal length f of the cemented lens group U2=-38mm, the focal length f of the cemented lens group U3=51mm, and the focal length f7 of the seventh lens G7=27mm. U3 In the optical system shown in the table, the distance L1=351mm, the distance L2=57mm, the focal length f1 of the first lens G1=391mm, the focal length f2 of the second lens G2=332mm, the focal length f of the cemented lens group U1=-158mm, the focal length f of the cemented lens group U2=-38mm, the focal length f of the cemented lens group U3=51mm, and the focal length f7 of the seventh lens G7=27mm.

[0065] The optical system is a double-telecentric structure, the working distance is 306mm, the object field of view is Φ150mm, the maximum aperture is F4.8, and the maximum imaging surface is Φ11mm.

[0066] Please refer to Figure 3 and Figure 4 , Figure 3 is an MTF curve of an optical system of a high-resolution low-distortion double-telecentric lens provided by the embodiment of the present application, Figure 4 is an optical distortion curve of an optical system of a high-resolution low-distortion double-telecentric lens provided by the embodiment of the present application.

[0067] As shown in Figure 3 , the MTF value of the optical system at 200lp / mm is greater than 0.3, and high-resolution imaging of the optical system can be realized.

[0068] As shown in Figure 4 , it can be seen that the distortion of the optical system is less than 0.02%, and the distortion is very small, which can meet the requirements of high-precision measurement.

[0069] The embodiment realizes a high-resolution low-distortion double-telecentric lens through the structural design of the above-mentioned optical system, the distortion of the full field of view is less than 0.02%, the resolution can reach 200lp / mm, and the high-resolution camera with a 2.5-micron pixel can be supported.

[0070] Embodiment Two:

[0071] Please refer to Figure 1 , Figure 1 is a structural schematic diagram of an optical system of a high-resolution low-distortion double-telecentric lens provided by the embodiment of the present application.

[0072] AsFigure 1 As shown in the figure, the optical system comprises, in order from the object side to the image side, a first lens G1 having positive refractive power, a second lens G2 having positive refractive power, a third lens G3 having positive refractive power, a fourth lens G4 having negative refractive power, a fifth lens G5 having negative refractive power, a sixth lens G6 having positive refractive power, a seventh lens G7 having positive refractive power, an eighth lens G8 having positive refractive power, and a ninth lens G9 having negative refractive power, and the optical axes of all the lenses coincide with the predetermined optical axis;

[0073] The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3;

[0074] The diaphragm S is arranged between the fourth lens G4 and the fifth lens G5; the light rays parallel to the first lens G1 are refracted by the second lens G2 and the cemented lens U1 and converge at the diaphragm S.

[0075] Further, the center distance between the front surface of the first lens G1 and the diaphragm S is L1, and the center distance between the diaphragm S and the image plane is L2;

[0076] The focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.3;

[0077] The first lens G1 converges the parallel incident light rays to the diaphragm S, and by satisfying the above relationship, on the one hand, the height of the light rays can be quickly reduced, which is beneficial to reducing the system length size, and on the other hand, the lenses behind can be brought together to the diaphragm position, thereby reducing the outer diameter size of the lenses.

[0078] Further, the focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3; the second lens G2 is far away from the first lens G1 and close to the diaphragm S side, which can maintain a small outer diameter size; as Figure 1 As shown in the figure, the second lens G2 is a crescent structure bending towards the diaphragm, which can moderate the incident light angle and balance the spherical aberration and coma;

[0079] The focal length f U1 of the cemented lens group U1 satisfies the relationship: 0.3<|f U1 / L1|<0.6; in this embodiment, the third lens G3 adopts a low-dispersion material, which can better correct chromatic aberration. Specifically, the refractive index of the third lens G3 is n3, and the Abbe number is v3, and n3 and v3 satisfy the relationship: 1.47<n3<60, 65<v3<82.

[0080] The focal length f U2 of the cemented lens group U2 satisfies the relationship: 0.5<|f U2|f7 / L2|<0.8; in this embodiment, the two lenses of the cemented lens group U2, i.e. the fifth lens G5 and the sixth lens G6, are made of a material with a relatively high refractive index, can bear a relatively large incident angle, and meanwhile maintain a proper shape, thereby forming a relatively small field curvature and spherical aberration.

[0081] The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35<|f7 / L2|<0.62;

[0082] The focal length f U3 satisfies the relationship: 0.75<|f U3 / L2|<1.05. In this embodiment, the refractive index of the eighth lens G8 is n8, and the refractive index of the ninth lens G9 is n9, which satisfy the relationship: n8

[0083] In this embodiment, the first lens G1 to the ninth lens G9 are all glass spherical lenses. Specifically, the first lens G1 is a glass spherical lens with a double-convex structure, the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all glass spherical lenses with a meniscus structure, the fifth lens G5 is a glass spherical lens with a double-concave structure, and the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses with a double-convex structure.

[0084] In this embodiment, the aperture of the diaphragm S is a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0085] The aperture adjustment range of the diaphragm is F4.8~F32.

[0086] For example, based on the above design idea, an optical system is designed in this embodiment, as shown in Table 2. Figure 5 The related data of the optical system are shown in Table 2.

[0087] Table 2

[0088] Surface Radius (mm) Thickness (mm) Refractive index Abbe number G1 front surface 394.4 19.1 1.85 24 G1 rear surface -779.5 191.4 G2 front surface 80.9 12.5 1.50 G2 rear surface 133.9 3.3 G3 front surface 27.2 14.7 1.50 80 G3, G4 cementing surface 162.5 14.2 1.75 G4 rear surface 17.1 22.0 Stop S ∞ 3.3 G5 front surface -8.9 1.6 1.92 G5, G6 cementing surface 32.0 5 . 4]] 1.75 G6 rear surface -12.3 0.9 G7 front surface 99.4 8.0 1.80 G7 rear surface -30.1 10.2 G8 front surface 56.6 8.0 1.94 G8, G9 cementing surface -37.8 7.8 1.95 30 G9 rear surface -143.8 16.7 Image surface /

[0089] It should be noted that in Table 2, the "front surface" corresponds to the left side surface of the corresponding lens or lens group in Figure 5 , and the "rear surface" corresponds to the right side surface of the corresponding lens or lens group in Figure 5 ; or it can be understood that: the object side is on the left side, and the image side (or image plane) is on the right side, the side surface close to the object side is the "front surface", and the side surface close to the image side is the "rear surface". Figure 5 Figure 1

[0090] ​​In the optical system shown in the above table, the distance L1 = 280 mm, the distance L2 = 62 mm, the focal length f1 of the first lens G1 = 304 mm, the focal length f2 of the second lens G2 = 338 mm, the focal length f of the cemented lens group U1 = -93 mm, the focal length f of the cemented lens group U2 = -48 mm, the focal length f of the cemented lens group U3 = 49 mm, and the focal length f7 of the seventh lens G7 = 29 mm. U1 U2 U3

[0091] In the second embodiment, the lens optical system is a double-telecentric structure, the working distance is 312 mm, the object field of view is Φ120 mm, the maximum aperture is F4.2, and the maximum imaging surface is φ11 mm.

[0092] Please refer to Figure 6 and Figure 7 , Figure 6 is the MTF curve of the optical system of another high-resolution low-distortion double-telecentric lens provided in the embodiment of the application when the working distance is 312 mm, Figure 7 is the optical distortion curve of the optical system of another high-resolution low-distortion double-telecentric lens provided in the embodiment of the application when the working distance is 312 mm.

[0093] As shown in Figure 6 , the MTF value of the optical system at 230 lp / mm is greater than 0.3, the highest can support a 2.2-micron pixel camera, and high-resolution imaging of the optical system can be realized.

[0094] As shown in Figure 7 , it can be seen that the distortion of the optical system is less than 0.012%, the distortion is very small, and the object can be measured almost without deformation.

[0095] The above-mentioned optical system is designed by the structure of the embodiment, and a high-resolution low-distortion double-telecentric lens is realized, the full-field distortion is less than 0.012%, the resolution can reach 230 lp / mm, and a 2.5-micron pixel high-resolution camera can be supported.

[0096] Embodiment three

[0097] The embodiment provides a high-resolution low-distortion double-telecentric lens, which comprises the optical system of the high-resolution low-distortion double-telecentric lens according to the first embodiment or the second embodiment.

[0098] Based on the detailed description of the optical system in the above-mentioned embodiments, the description is not repeated in this embodiment.

[0099] Further, the embodiment also provides a 2.5-micron pixel camera, which is assembled with the high-resolution low-distortion double-telecentric lens.​​​

[0100] In summary, the embodiment of the present application realizes a high-resolution low-distortion double-telecentric lens, the full field distortion is less than 0.02%, the resolution can reach 200 lp / mm, can adapt to a high-resolution camera with 2.5 micron pixels, and effectively improves the measurement accuracy.

[0101] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the foregoing embodiments of the present application have been described in detail, those skilled in the art should understand: the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical system of a high-resolution low-distortion dual-telecentric lens, characterized by, The first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7, the eighth lens G8 and the ninth lens G9 are sequentially arranged from the object side to the image side, and all the lenses have the same optical axis as the predetermined optical axis; The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3; The stop S is arranged between the fourth lens G4 and the fifth lens G5, and the light parallel to the first lens G1 is refracted by the second lens G2 and the cemented lens U1 and converges at the stop S; The first lens G1 is a double-convex glass spherical lens, the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all double-concave glass spherical lenses, the fifth lens G5 is a double-convex glass spherical lens, and the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all double-convex glass spherical lenses; wherein the convex surface of the third lens G3 and the fourth lens G4 and the concave surface of the ninth lens G9 are arranged towards the object side; The center distance between the front surface of the first lens G1 and the stop S is L1, and the focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.

3.

2. The optical system of claim 1, wherein, The center distance between the stop S and the image plane is L2; The focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3; focal length f of the cemented lens group U1 U1 satisfies the relationship: 0.3<|f U1 / L1|<0.6; focal length f of the cemented lens group U2 U2 satisfies the relationship: 0.5<|f U2 / L2|<0.8; The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35<|f7 / L2|<0.62; focal length f of the cemented lens group U3 U3 satisfies the relationship: 0.75<|f U3 / L2|<1.

05.

3. The optical system of a high-resolution low-distortion dual-telecentric lens according to claim 2, characterized in that, The refractive index of the third lens G3 is n3, and the Abbe number is v3, and n3 and v3 satisfy the relationships: 1.47<n3<60 and 65<v3<82, respectively.

4. The optical system of claim 2, wherein, The refractive index of the eighth lens G8 is less than that of the ninth lens G9.

5. The optical system of claim 1, wherein the high-resolution low-distortion dual-telecentric lens is characterized by: The stop S has a circular aperture, and the center of the circular aperture is on the predetermined optical axis; The aperture adjustment range of the stop is F4.8~F32.

6. A high resolution, low distortion double telecentric lens characterized by, An optical system comprising a high-resolution low-distortion double-telecentric lens according to any one of claims 1-5.

7. A 2.5 micron pixel camera, characterized by, A high-resolution low-distortion double-telecentric lens according to claim 6.

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