A double-rate large-field telecentric lens

Abstract

The present invention discloses a double magnification large field of view telecentric lens, which includes a first lens group, a prism assembly, a second lens group, and a third lens group. The prism assembly is a semi-transmissive and semi-reflective prism. The first lens group is located in the incident light direction of the prism assembly, the second lens group is located in the transmitted light direction of the prism assembly, and the third lens group is located in the reflected light direction of the prism assembly. The first lens group, the prism assembly, and the second lens group are on a straight line, and the first lens group and the third lens group are perpendicular to each other at the prism assembly. With the above structure, the telecentric lens of the present invention has two magnifications of different sizes, realizes the simultaneous use of the double magnification of the telecentric lens, and selects a suitable magnification for the measurement of products of different sizes. Compared with the telecentric lens with a single magnification, it has the advantages of a wide application range and high detection efficiency.

Description

Technical Field

[0001] The present invention relates to the field of telecentric optical systems, and in particular to a double magnification large field of view telecentric lens. Background Art

[0002] In a machine vision precision measurement system, there are some problems when using ordinary industrial lenses. For example, changes in object distance will cause different magnification ratios, parallax, large distortion, etc., making it difficult to meet high detection requirements. While telecentric lenses can reduce or even eliminate the above problems. They can make the magnification ratio of the obtained image not change with the change of object distance within a certain range of object distances. Its principle advantages make it very suitable for the field of machine vision measurement and detection.

[0003] However, the telecentric lenses used in actual industrial measurements have a fixed magnification ratio. In industrial on-site production, the sizes of products are different, and the items to be detected are also diverse. It is extremely troublesome to replace the lens for detection every time. Therefore, there is an urgent need to design a lens with convertible multiple magnification ratios, which can convert to a small magnification ratio and also switch to a large magnification ratio when measuring the same component, avoiding the trouble of frequently replacing the lens when measuring the same workpiece. Summary of the Invention

[0004] In order to implement the above telecentric lens, the object of the present invention is to provide a double magnification large field of view telecentric lens. This telecentric lens has two different magnification ratios, can be connected to two cameras for detection simultaneously, greatly improves the efficiency of product detection, and the selective use of different magnification ratios enhances the flexibility of use of this telecentric lens, meeting the needs of different detection occasions.

[0005] The technical solution adopted by the present invention is: comprising: a first lens group, a prism assembly, a second lens group, and a third lens group;

[0006] The first lens group includes a first lens with positive optical power and a plano-convex structure, and a second lens with positive optical power and a plano-convex structure;

[0007] The prism assembly is a semi-transmissive and semi-reflective prism;

[0008] The second lens group includes a third lens with negative optical power and a convex-concave structure, a first aperture stop, a first cemented lens with negative optical power, and a fourth lens with positive optical power and a biconvex structure;

[0009] The third lens group includes a fifth lens with positive optical power and a convex-concave structure, a second cemented lens with negative optical power, a second aperture stop, a third cemented lens with positive optical power, and a sixth lens with positive optical power and a biconvex structure;

[0010] The first lens group is located in the incident light direction of the prism assembly, the second lens group is located in the transmitted light direction of the prism assembly, and the third lens group is located in the reflected light direction of the prism assembly. The first lens group, the prism assembly, and the second lens group are on a straight line, and the first lens group and the third lens group are perpendicular to each other at the prism assembly.

[0011] Further, the first cemented lens is composed of a seventh lens with a negative optical power and a double-concave structure and an eighth lens with a positive optical power and a double-convex structure, which are cemented together using optical cement.

[0012] Further, the second cemented lens is composed of a ninth lens with a positive optical power and a plano-convex structure and a tenth lens with a negative optical power and a concave-convex structure, which are cemented together using optical cement.

[0013] Further, the third cemented lens is composed of an eleventh lens with a negative optical power and a double-concave structure and a twelfth lens with a positive optical power and a double-convex structure, which are cemented together using optical cement.

[0014] Further, the material of the first lens is H-K9L glass, the material of the second lens is H-ZF52 glass, the material of the third lens is H-ZK2 glass, the material of the seventh lens of the first cemented lens is H-ZLAF75A glass, the material of the eighth lens of the first cemented lens is H-ZK3 glass, the material of the fourth lens is H-ZK11 glass, the material of the fifth lens is H-ZF3 glass, the material of the ninth lens of the second cemented lens is H-ZK9B glass, the material of the tenth lens of the second cemented lens is H-ZF50 glass, the material of the eleventh lens of the third cemented lens is H-ZK2 glass, the material of the twelfth lens of the third cemented lens is H-K50 glass, and the material of the sixth lens is H-LAF54 glass.

[0015] Further, the clear aperture of the first lens is Φ161(-0.14, -0.04)mm, the central thickness is 18 ± 0.05mm, the clear aperture of the second lens is Φ150(-0.14, -0.04)mm, the central thickness is 13 ± 0.05mm, the clear aperture of the third lens is Φ15(-0.04, -0.02)mm, the central thickness is 5.81 ± 0.02mm, the clear aperture of the seventh lens of the first cemented lens is Φ13(-0.04, -0.02)mm, the central thickness is 2.91 ± 0.02mm, the clear aperture of the eighth lens of the first cemented lens is Φ13(-0.04, -0.02)mm, the central thickness is 5.46 ± 0.02mm, the clear aperture of the fourth lens is Φ15(-0.04, -0.02)mm, the central thickness is 3.73 ± 0.02mm, the clear aperture of the fifth lens is Φ13(-0.04, -0.02)mm, the central thickness is 7.45 ± 0.02mm, the clear aperture of the ninth lens of the second cemented lens is Φ13(-0.04, -0.02)mm, the central thickness is 6.9 ± 0.02mm, the clear aperture of the tenth lens of the second cemented lens is Φ13(-0.04, -0.02)mm, the central thickness is 3.04 ± 0.02mm, the clear aperture of the eleventh lens of the third cemented lens is Φ13(-0.04, -0.02)mm, the central thickness is 2.14 ± 0.02mm, the clear aperture of the twelfth lens of the third cemented lens is Φ13(-0.04, -0.02)mm, the central thickness is 5.72 ± 0.02mm, and the clear aperture of the sixth lens is Φ17(-0.04, -0.02)mm, the central thickness is 4.03 ± 0.02mm.

[0016] Further, the prism assembly is a cube structure made of H-K9L glass coated with a semi-transparent and semi-reflective material, with a reflectivity of 50% and a transmittance of 50%, and a clear aperture of 50*50(-0.2, -0.1)mm.

[0017] Advantages of the present invention:

[0018] The present invention relates to a double magnification large field of view telecentric lens, which includes a first lens group, a prism assembly, a second lens group, and a third lens group. The first lens group is located in the incident light direction of the prism assembly, the second lens group is located in the transmitted light direction of the prism assembly, and the third lens group is located in the reflected light direction of the prism assembly. The first lens group, the prism assembly, and the second lens group are on a straight line, and the first lens group and the third lens group are perpendicular to each other at the prism assembly. In the present invention, a prism assembly is added to the telecentric optical system. The prism assembly is a semi-transmissive and semi-reflective prism, which makes 50% of the incident light reflect and 50% transmit, corresponding to two different optical paths, and can connect two cameras for simultaneous detection, greatly improving the detection efficiency. This telecentric lens has two magnification ratios, corresponding to a large field of view range and a small field of view range respectively, and can accurately collect product information features within different field of view ranges, improving the flexibility of use of the telecentric lens and meeting the needs of different detection occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a schematic diagram of the optical system of a double magnification large field of view telecentric lens proposed by the present invention;

[0020] Figure 2 FIG. is a schematic diagram of the optical structure of a double magnification large field of view telecentric lens proposed by the present invention;

[0021] Figure 3 FIG. is an optical modulation transfer function diagram of the optical system of a double magnification large field of view telecentric lens with a small magnification at room temperature proposed by the present invention;

[0022] Figure 4 FIG. is an optical modulation transfer function diagram of the optical system of a double magnification large field of view telecentric lens with a large magnification at room temperature proposed by the present invention;

[0023] Figure 5 FIG. is a schematic diagram of the distortion curve of the optical system of a double magnification large field of view telecentric lens with a small magnification proposed by the present invention;

[0024] Figure 6 FIG. is a schematic diagram of the distortion curve of the optical system of a double magnification large field of view telecentric lens with a large magnification proposed by the present invention.

[0025] DESCRIPTION OF THE REFERENCE NUMERALS

[0026] 100 - The first lens group, 110 - The first lens, 120 - The second lens, 200 - The prism assembly, 300 - The second lens group, 310 - The third lens, 320 - The first aperture stop, 330 - The first cemented lens, 331 - The seventh lens, 332 - The eighth lens, 340 - The fourth lens, 400 - The third lens group, 410 - The fifth lens, 420 - The second cemented lens, 421 - The ninth lens, 422 - The tenth lens, 430 - The second aperture stop, 440 - The third cemented lens, 441 - The eleventh lens, 442 - The twelfth lens, 450 - The sixth lens. Detailed implementation manners

[0027] The following describes the detailed implementation manners of the present invention in conjunction with the accompanying drawings and embodiments:

[0028] It should be noted that the structures, ratios, sizes, etc. illustrated in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the implementation conditions of the present invention. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention.

[0029] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of clear narration, and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope that the present invention can implement.

[0030] As Figure 1 、 Figure 2 shown, it shows the detailed implementation manners of the present invention; A double magnification large field of view telecentric lens disclosed by the present invention includes: the first lens group 100, the prism assembly 200, the second lens group 300, and the third lens group 400;

[0031] The first lens group 100 includes the first lens 110 having a positive optical power and a plano-convex structure, and the second lens 120 having a positive optical power and a plano-convex structure;

[0032] The prism assembly 200 is a semi-transmissive and semi-reflective prism;

[0033] The second lens group 300 includes the third lens 310 having a negative optical power and a convex-concave structure, the first aperture stop 320, the first cemented lens 330 having a negative optical power, and the fourth lens 340 having a positive optical power and a biconvex structure;

[0034] The third lens group 400 described above includes a fifth lens 410 with a positive focal power and a convex-concave structure, a second cemented lens 420 with a negative focal power, a second aperture stop 430, a third cemented lens 440 with a positive focal power, and a sixth lens 450 with a positive focal power and a biconvex structure;

[0035] The first lens group 100 is located in the incident light direction of the prism assembly 200, the second lens group 300 is located in the transmitted light direction of the prism assembly 200, the third lens group 400 is located in the reflected light direction of the prism assembly 200. The first lens group 100, the prism assembly 200, and the second lens group 300 are on a straight line, and the first lens group 100 and the third lens group 400 are perpendicular to each other at the prism assembly 200.

[0036] Preferably, the first cemented lens 330 is composed of a seventh lens 331 with a negative focal power and a biconcave structure and an eighth lens 332 with a positive focal power and a biconvex structure, which are cemented together with an optical adhesive.

[0037] Preferably, the second cemented lens 420 is composed of a ninth lens 421 with a positive focal power and a plano-convex structure and a tenth lens 422 with a negative focal power and a convex-concave structure, which are cemented together with an optical adhesive.

[0038] Preferably, the third cemented lens 440 is composed of an eleventh lens 441 with a negative focal power and a biconcave structure and a twelfth lens 442 with a positive focal power and a biconvex structure, which are cemented together with an optical adhesive.

[0039] In the present invention, as Figure 1 、 Figure 2 shown, there are a total of twelve lenses and one semi-transmissive and semi-reflective mirror in this telecentric lens. Among them, the twelve lenses all adopt a spherical structure that is easy to process, and the semi-transmissive and semi-reflective mirror is a plane mirror.

[0040] Preferably, as Figure 1 、 Figure 2 shown, the first lens 110 is a spherical lens made of H-K9L glass, with a clear aperture of Φ161 (-0.14, -0.04) mm and a central thickness of 18 ± 0.05 mm.

[0041] The parameters in the brackets are the tolerance ranges. This description is standard and the tolerance range description in a commonly used optical system in the art. This embodiment is a negative tolerance, and the purpose is to obtain ideal imaging parameters of the optical system.

[0042] The following description of the tolerance is also the same.

[0043] Preferably, as Figure 1 、 Figure 2As shown, the second lens 120 is a spherical lens made of H-ZF52 glass, with an aperture diameter of Φ150(-0.14, -0.04)mm and a central thickness of 13±0.05mm.

[0044] Preferably, as Figure 1 、 Figure 2 As shown, the third lens 310 is a spherical lens made of H-ZK2 glass, with an aperture diameter of Φ15(-0.04, -0.02)mm and a central thickness of 5.81±0.02mm.

[0045] Preferably, as Figure 1 、 Figure 2 As shown, the seventh lens 331 of the first cemented lens 330 is a spherical lens made of H-ZLAF75A glass, with an aperture diameter of Φ13(-0.04, -0.02)mm and a central thickness of 2.91±0.02mm.

[0046] Preferably, as Figure 1 、 Figure 2 As shown, the eighth lens 332 of the first cemented lens 330 is a spherical lens made of H-ZK3 glass, with an aperture diameter of Φ13(-0.04, -0.02)mm and a central thickness of 5.46±0.02mm.

[0047] Preferably, as Figure 1 、 Figure 2 As shown, the fourth lens 340 is a spherical lens made of H-ZK11 glass, with an aperture diameter of Φ15(-0.04, -0.02)mm and a central thickness of 3.73±0.02mm.

[0048] Preferably, as Figure 1 、 Figure 2 As shown, the fifth lens 410 is a spherical lens made of H-ZF3 glass, with an aperture diameter of Φ13(-0.04, -0.02)mm and a central thickness of 7.45±0.02mm.

[0049] Preferably, as Figure 1 、 Figure 2 As shown, the ninth lens 421 of the second cemented lens 420 is a spherical lens made of H-ZK9B glass, with an aperture diameter of Φ13(-0.04, -0.02)mm and a central thickness of 6.9±0.02mm.

[0050] Preferably, as Figure 1 、 Figure 2As shown, the tenth lens 422 of the second cemented lens 420 is a spherical lens made of H-ZF50 glass, with a clear aperture of Φ13 (-0.04, -0.02) mm and a central thickness of 3.04 ± 0.02 mm.

[0051] Preferably, as Figure 1 , Figure 2 shown, the eleventh lens 441 of the third cemented lens 440 is a spherical lens made of H-ZK2 glass, with a clear aperture of Φ13 (-0.04, -0.02) mm and a central thickness of 2.14 ± 0.02 mm.

[0052] Preferably, as Figure 1 , Figure 2 shown, the twelfth lens 442 of the third cemented lens 440 is a spherical lens made of H-K50 glass, with a clear aperture of Φ13 (-0.04, -0.02) mm and a central thickness of 5.72 ± 0.02 mm.

[0053] Preferably, as Figure 1 , Figure 2 shown, the sixth lens 450 is a spherical lens made of H-LAF54 glass, with a clear aperture of Φ17 (-0.04, -0.02) mm and a central thickness of 4.03 ± 0.02 mm.

[0054] Preferably, the prism assembly 200 is a cube structure made of H-K9L glass coated with a semi-transmissive and semi-reflective material, with a reflectivity of 50% and a transmittance of 50%, and a clear aperture of 50 * 50 (-0.2, -0.1) mm.

[0055] As Figure 3 shown is the optical modulation transfer function graph of the optical system of a double-rate large-field telecentric lens with a small magnification at room temperature proposed by the present invention. The abscissa is the spatial modulation frequency, and the ordinate is the optical modulation function. It can be seen that the lens of the present invention has good high-quality imaging quality at room temperature and normal pressure.

[0056] As Figure 4 shown is a schematic diagram of the distortion curve of the optical system of a double-rate large-field telecentric lens with a small magnification proposed by the present invention. The abscissa is the percentage of optical distortion, and the ordinate is the field angle of the optical system. It can be seen that the distortion of the optical lens of the present invention is less than 0.1%, with a small amount of distortion.

[0057] As Figure 5 shown is the optical modulation transfer function graph of the optical system of a double-rate large-field telecentric lens with a large magnification at room temperature proposed by the present invention. The abscissa is the spatial modulation frequency, and the ordinate is the optical modulation function. It can be seen that the lens of the present invention has good high-quality imaging quality at room temperature and normal pressure.

[0058] As shown Figure 6 in the figure is a schematic diagram of the distortion curve of a double-rate large-field telecentric lens with a large magnification optical system proposed by the present invention. The abscissa is the optical distortion percentage, and the ordinate is the field of view angle of the optical system. It can be seen that the distortion of the optical lens of the present invention is less than 0.1%, and has a small distortion amount.

[0059] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

[0060] Many other changes and modifications can be made without departing from the concept and scope of the present invention. It should be understood that the present invention is not limited to specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A double-rate large-field telecentric lens, comprising: a first lens group (100), a prism assembly (200), a second lens group (300), and a third lens group (400); The first lens group (100) includes a first lens (110) having a positive focal power and a plano-convex structure, and a second lens (120) having a positive focal power and a plano-convex structure; The prism assembly (200) is a semi-transmissive and semi-reflective prism; The second lens group (300) includes a third lens (310) having a negative focal power and a convex-concave structure, a first aperture stop (320), a first cemented lens (330) having a negative focal power, and a fourth lens (340) having a positive focal power and a bi-convex structure; The third lens group (400) includes a fifth lens (410) having a positive focal power and a convex-concave structure, a second cemented lens (420) having a negative focal power, a second aperture stop (430), a third cemented lens (440) having a positive focal power, and a sixth lens (450) having a positive focal power and a bi-convex structure; The first lens group (100) is located in the incident light direction of the prism assembly (200), the second lens group (300) is located in the transmitted light direction of the prism assembly (200), the third lens group (400) is located in the reflected light direction of the prism assembly (200). The first lens group (100), the prism assembly (200), and the second lens group (300) are on a straight line, and the first lens group (100) and the third lens group (400) are perpendicular to each other at the prism assembly (200); The first cemented lens (330) is composed of a seventh lens (331) having a negative focal power and a bi-concave structure and an eighth lens (332) having a positive focal power and a bi-convex structure, which are cemented with an optical adhesive; The second cemented lens (420) is composed of a ninth lens (421) having a positive focal power and a plano-convex structure and a tenth lens (422) having a negative focal power and a convex-concave structure, which are cemented with an optical adhesive; The third cemented lens (440) is composed of an eleventh lens (441) having a negative focal power and a bi-concave structure and a twelfth lens (442) having a positive focal power and a bi-convex structure, which are cemented with an optical adhesive.

2. A double-rate large-field telecentric lens according to claim 1, characterized in that: The material of the first lens (110) is H-K9L glass; The material of the second lens (120) is H-ZF52 glass; The material of the third lens (310) is H-ZK2 glass; The material of the seventh lens (331) of the first cemented lens (330) is H-ZLAF75A glass; The material of the eighth lens (332) of the first cemented lens (330) is H-ZK3 glass; The material of the fourth lens (340) is H-ZK11 glass; The material of the fifth lens (410) is H-ZF3 glass; The material of the ninth lens (421) of the second cemented lens (420) is H-ZK9B glass; The material of the tenth lens (422) of the second cemented lens (420) is H-ZF50 glass; The material of the eleventh lens (441) of the third cemented lens (440) is H-ZK2 glass; The material of the twelfth lens (442) of the third cemented lens (440) is H-K50 glass; The material of the sixth lens (450) is H-LAF54 glass.

3. A double magnification large field of view telecentric lens according to claim 1, characterized in that: The clear aperture of the first lens (110) is Φ161 (-0.14, -0.04) mm, and the center thickness is 18 ± 0.05 mm; The clear aperture of the second lens (120) is Φ150 (-0.14, -0.04) mm, and the center thickness is 13 ± 0.05 mm; The clear aperture of the third lens (310) is Φ15 (-0.04, -0.02) mm, and the center thickness is 5.81 ± 0.02 mm; The clear aperture of the seventh lens (331) of the first cemented lens (330) is Φ13 (-0.04, -0.02) mm, and the center thickness is 2.91 ± 0.02 mm; The clear aperture of the eighth lens (332) of the first cemented lens (330) is Φ13 (-0.04, -0.02) mm, and the center thickness is 5.46 ± 0.02 mm; The clear aperture of the fourth lens (340) is Φ15 (-0.04, -0.02) mm, and the center thickness is 3.73 ± 0.02 mm; The clear aperture of the fifth lens (410) is Φ13 (-0.04, -0.02) mm, and the center thickness is 7.45 ± 0.02 mm; The clear aperture of the ninth lens (421) of the second cemented lens (420) is Φ13 (-0.04, -0.02) mm, and the center thickness is 6.9 ± 0.02 mm; The clear aperture of the tenth lens (422) of the second cemented lens (420) is Φ13 (-0.04, -0.02) mm, and the center thickness is 3.04 ± 0.02 mm; The clear aperture of the eleventh lens (441) of the third cemented lens (440) is Φ13 (-0.04, -0.02) mm, and the center thickness is 2.14 ± 0.02 mm; The clear aperture of the twelfth lens (442) of the third cemented lens (440) is Φ13 (-0.04, -0.02) mm, and the center thickness is 5.72 ± 0.02 mm; The clear aperture of the sixth lens (450) is Φ17 (-0.04, -0.02) mm, and the center thickness is 4.03 ± 0.02 mm.

4. A double magnification large field of view telecentric lens according to claim 1, characterized in that, The material of the prism assembly (200) is H-K9L glass, with a cube structure coated with a semi-transparent and semi-reflective film, a reflectivity of 50%, a transmittance of 50%, and a clear aperture of 50 × 50 (-0.2, -0.1) mm.

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