Dual field measurement lens and optical system thereof

Abstract

The application relates to the technical field of machine vision lenses, and discloses a double-view measurement lens and an optical system thereof. The optical system comprises a front group, a light splitting prism and a rear group arranged in sequence from an object side to an image side; the rear group comprises a first-magnification rear group arranged on a refractive path of the light splitting prism and a second-magnification rear group arranged on a reflection path of the light splitting prism; a first diaphragm is arranged between the first-magnification rear group and the light splitting prism, and the first diaphragm is arranged at a combined focal length of the front group on the refractive path; a second diaphragm is arranged between the second-magnification rear group and the light splitting prism, and the second diaphragm is arranged at a combined focal length of the front group on the reflection path. The optical system provided by the application has a compact structure, two rear groups with different magnifications, and can be connected with two cameras to simultaneously perform detection, realize simultaneous measurement of a large view field and a small view field, shorten the measurement time while improving the precision, and improve the test efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machine vision lens, and in particular to a dual-view measurement lens and an optical system thereof. BACKGROUND

[0002] With the rapid development of the machine vision industry, image instruments based on visual detection can realize accurate measurement and analysis of product size, shape and surface features, and have been rapidly popularized in the industrial manufacturing field, such as 3C electronic factories and precision hardware processing factories. Many image measurement lenses on the market have only a single view and a single magnification, and cannot realize simultaneous measurement by dual cameras, resulting in low measurement efficiency. Existing dual-view image measurement lenses have the problem of long structure length, resulting in bulky optical structures.

[0003] Therefore, for those skilled in the art, how to improve the precision while shortening the measurement time and improving the test efficiency has become a technical problem to be solved in the art.

[0004] The above information is given as background information only to assist with an understanding of the present disclosure, and does not constitute a admission 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 dual-view measurement 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 dual-view measurement lens, comprising a front group with positive focal power, a light splitting prism and a rear group arranged in order from the object side to the image side;

[0008] The front group comprises a first lens with positive focal power, a second lens with positive focal power, a third lens with positive focal power and a fourth lens with negative focal power; wherein the third lens and the fourth lens form a first cemented lens with negative focal power;

[0009] The rear group comprises a first magnification rear group with positive focal power arranged on the refractive path of the light splitting prism and a second magnification rear group with positive focal power arranged on the reflection path of the light splitting prism;

[0010] A first diaphragm is arranged between the first magnification rear group and the light splitting prism, and the first diaphragm is arranged at the combined focal length of the front group on the refractive path; a second diaphragm is arranged between the second magnification rear group and the light splitting prism, and the second diaphragm is arranged at the combined focal length of the front group on the reflection path.

[0011] Optionally, the combined focal length of the front group is f 100 , the focal length of the first lens is f 110 , the focal length of the second lens 120 is f 120 , the focal length of the first cemented lens is f U1 ;

[0012] f 110 and f 100 satisfy the relationship: 1.5<|f 110 / f 100 |<2.5;

[0013] f 110 and f 120 satisfy the relationship: 0.75<|f 110 / f 120 |<1.25;

[0014] f U1 and f 100 satisfy the relationship: 0.5<|f U1 / f 100 |<0.75.

[0015] Optionally, the first magnification rear group comprises, in order from the first diaphragm to the first image plane, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with positive optical power; wherein the fifth lens and the sixth lens form a second cemented lens with negative optical power;

[0016] The combined focal length of the first magnification rear group is f 200 , the focal length of the second cemented lens is f U2 , the focal length of the seventh lens is f 230 , and the focal length of the eighth lens is f 240 ;

[0017] f 230 and f 200 satisfy the relationship: 1.4<|f 230 / f 200 |<3;

[0018] f 240 and f 200 satisfy the relationship: 1.2<|f 240 / f 200 |<2;

[0019] f U2 and f 200 satisfy the relationship: 1.5<|f U2 / f 200 |<2.5.

[0020] Optionally, the second magnification rear group comprises, in sequence from the second diaphragm to the second image plane, a ninth lens with negative focal power, a tenth lens with positive focal power, an eleventh lens with positive focal power, and a twelfth lens with positive focal power; wherein the ninth lens and the tenth lens form a third cemented lens with negative focal power.

[0021] The combined focal length of the second magnification rear group is f 300 , the focal length of the third cemented lens is f U3 , the focal length of the eleventh lens is f 330 , and the focal length of the twelfth lens is f 340 .

[0022] f U3 and f 300 satisfy the relationship: 1.6<|f U3 / f 300 |<2.6.

[0023] f 330 and f 300 satisfy the relationship: 2<|f 330 / f 300 |<3.

[0024] f 340 and f 300 satisfy the relationship: 1.8<|f 340 / f 300 |<2.8.

[0025] Optionally, in the front group, the first lens is a plano-convex lens or a meniscus lens, and the second lens, the third lens, and the fourth lens are all meniscus lenses.

[0026] In the first magnification rear group, the fifth lens is a double-concave lens, and the sixth lens, the seventh lens, and the eighth lens are all double-convex lenses.

[0027] In the second magnification rear group, the ninth lens is a double-concave lens, and the tenth lens, the eleventh lens, and the twelfth lens are all double-convex lenses.

[0028] Optionally, the light splitting prism is a semi-transparent semi-reflective prism.

[0029] Optionally, the materials of the second lens and the third lens are crown glass.

[0030] Optionally, the optical axes of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are all on a predetermined first optical axis; the optical axes of the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens are all on a predetermined second optical axis; and the first optical axis and the second optical axis are perpendicular.

[0031] The center of the aperture of the first diaphragm is on the first optical axis, and the center of the aperture of the second diaphragm is on the second optical axis.

[0032] Optionally, the magnification of the first magnification rear group is less than the magnification of the second magnification rear group.

[0033] In a second aspect, the application provides a dual-view measurement lens, comprising an optical system of a dual-view measurement lens as described above.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] The application realizes a dual-view measurement lens, which is compact in structure and can effectively compress the length size; the dual-view measurement lens has two rear groups with different magnifications, so that two cameras can be connected to perform detection at the same time, large and small fields of view can be measured at the same time, the measurement time is shortened while the accuracy is improved, and the test efficiency is improved.

[0036] The application has other characteristics and advantages, which will be apparent or will be described in detail in the drawings and subsequent specific embodiments incorporated herein, which are collectively used to explain the specific principles of the application. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0038] Figure 1 is a structural schematic diagram of an optical system of a dual-view measurement lens provided by the embodiments of the application.

[0039] Figure 2 is an optical path diagram of an optical system of a dual-view measurement lens provided by the embodiments of the application.

[0040] Figure 3 is a structural schematic diagram of a front group provided by the embodiments of the application.

[0041] Figure 4 is a structural schematic diagram of a first magnification rear group provided by the embodiments of the application.

[0042] Figure 5 is a structural schematic diagram of a second magnification rear group provided by the embodiments of the application.

[0043] Figure 6The MTF diagram of the small magnification optical system provided for the embodiment of the present application.

[0044] Figure 7 The MTF diagram of the large magnification optical system provided for the embodiment of the present application.

[0045] Figure 8 The distortion diagram of the small magnification optical system provided for the embodiment of the present application.

[0046] Figure 9 The distortion diagram of the large magnification optical system provided for the embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to make the possible application scenarios, technical principles, specific schemes that can be implemented, purposes and effects achieved, etc. of the present application clear, the following will be described in detail in combination with the specific embodiments listed and with the accompanying drawings. The embodiments described herein 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.

[0048] In this document, the term "embodiment" means that the specific features, structures or characteristics described in combination with the embodiment can be included 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, each technical feature mentioned in each embodiment can be combined in any way to form a corresponding implementable technical scheme.

[0049] Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the art to which the present application belongs; the use of related terms in this document is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0050] In the description of the present application, the word "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 this document generally represents that the associated objects before and after are a "or" logical relationship.

[0051] In the present application, the terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary and secondary or order relationship between the entities or operations.

[0052] In the present application, the terms "comprise", "contain", "include", or other similar phrases as used in a clause means to encompass the non-exclusive inclusion, and the terms 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 can not only include those limited elements, but also include other elements not explicitly listed, or also include elements inherent to such process, method, or product.

[0053] As understood in the same way as in the "Examination Guidelines", in the present application, the expressions "greater than", "less than", "exceed" and the like are understood as not including the number; the expressions "above", "below", "within" and the like 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.

[0054] In the description of the embodiments of the present application, the spatial-related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "perpendicular", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or the drawings, and are only for the convenience of describing the specific embodiments of the present application or for the reader to understand, and do 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.

[0055] Unless otherwise explicitly specified or limited, in the description of the embodiments of the present application, the terms "mount", "connect", "connect", "fix", "set", and the like should be understood broadly. 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 communication or 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.

[0056] Embodiment one:

[0057] Please refer to Figure 1 and Figure 2 , Figure 1 is a structural schematic diagram of an optical system of a dual-view measurement lens provided by the embodiments of the present application, Figure 2A light path diagram of an optical system of a dual-view field measurement lens is provided for an embodiment of the present application.

[0058] As shown in Figure 1 , the optical system comprises:

[0059] comprises a front group 100 with positive focal power, a beam splitter BS and a rear group arranged in order from the object side to the image side;

[0060] The front group 100 comprises a first lens 110 with positive focal power, a second lens 120 with positive focal power, a third lens 130 with positive focal power and a fourth lens 140 with negative focal power; wherein the third lens 130 and the fourth lens 140 form a first cemented lens U1 with negative focal power;

[0061] The rear group comprises a first magnification rear group 200 with positive focal power arranged on the refractive path of the beam splitter BS and a second magnification rear group 300 with positive focal power arranged on the reflection path of the beam splitter BS;

[0062] A first stop S1 is arranged between the first magnification rear group 200 and the beam splitter BS, and the first stop S1 is arranged at the combined focal length of the front group 100 on the refractive path; a second stop S2 is arranged between the second magnification rear group 300 and the beam splitter BS, and the second stop S2 is arranged at the combined focal length of the front group 100 on the reflection path.

[0063] Please refer to Figures 3-5 , Figure 3 The structure schematic diagram of the front group 100 provided for an embodiment of the present application, Figure 4 The structure schematic diagram of the first magnification rear group 200 provided for an embodiment of the present application, Figure 5 The structure schematic diagram of the second magnification rear group 300 provided for an embodiment of the present application;

[0064] As shown in Figure 4 and Figure 5 , the first magnification rear group 200 is placed along the transmission light direction of the beam splitter BS, and the second magnification rear group 300 is placed along the reflection light direction of the beam splitter BS; the first stop S1 and the second stop S2 are both located at the combined focal length of the front group 100, forming a telecentric architecture to reduce measurement error.

[0065] Further, the combined focal length of the front group 100 is f 100 , the focal length of the first lens 110 is f 110 , the focal length of the second lens 120 is f 120 , and the focal length of the first cemented lens U1 is f U1 ;

[0066] f 110 and f 100Satisfies the relation: 1.5 < |f 110 / f 100 |<2.5;

[0067] f 110 and f 120 The relation is satisfied: 0.75 < |f 110 / f 120 |<1.25;

[0068] f U1 and f 100 Satisfies the relation: 0.5 < |f U1 / f 100 |<0.75.

[0069] like Figure 3 As shown, in this embodiment, the first lens 110 and the second lens 120 have similar focal lengths, which can better share the ability to deflect light, which is beneficial to compressing the system length. At the same time, the incident angle of light will not be too large, reducing off-axis aberrations.

[0070] Furthermore, the first magnification rear group 200 includes a fifth lens 210 with negative optical power, a sixth lens 220 with positive optical power, a seventh lens 230 with positive optical power, and an eighth lens 240 with positive optical power, arranged sequentially from the first aperture S1 to the first image plane; wherein, the fifth lens 210 and the sixth lens 220 form a second cemented lens U2 with negative optical power.

[0071] The combined focal length of the first magnification group 200 is f. 200 The focal length of the second cemented lens U2 is f. U2 The focal length of the seventh lens 230 is f. 230 The focal length of the eighth lens 240 is f. 240 ;

[0072] f 230 and f 200 Satisfies the relation: 1.4 < |f 230 / f 200 |<3;

[0073] f 240 and f 200 The relation 1.2 < |f is satisfied. 240 / f 200 |<2;

[0074] f U2 and f 200 Satisfies the relation: 1.5 < |f U2 / f 200 |<2.5.

[0075] The front group 100 causes the light rays to enter the first power rear group 200 at an increased angle due to the length compression, and the sixth lens 220, the seventh lens 230 and the eighth lens 240 all have positive focal power and a double-convex structure, which is conducive to reducing the aberration caused by the light rays entering at a large angle. In the embodiment, the seventh lens 230 and the eighth lens 240 are made of a glass material with a high refractive index, which is conducive to relaxing the angle of incidence of the light rays entering the lens and reducing the tolerance sensitivity.

[0076] Specifically, the second power rear group 300 includes, sequentially from the second stop S2 to the second image plane, a ninth lens 310 with negative focal power, a tenth lens 320 with positive focal power, an eleventh lens 330 with positive focal power, and a twelfth lens 340 with positive focal power; wherein the ninth lens 310 and the tenth lens 320 form a third cemented lens U3 with negative focal power.

[0077] The combined focal length of the second power rear group 300 is f 300 , the focal length of the third cemented lens U3 is f U3 , the focal length of the eleventh lens 330 is f 330 , and the focal length of the twelfth lens 340 is f 340 .

[0078] f U3 and f 300 satisfy the relationship: 1.6<|f U3 / f 300 |<2.6.

[0079] f 330 and f 300 satisfy the relationship: 2<|f 330 / f 300 |<3.

[0080] f 340 and f 300 satisfy the relationship: 1.8<|f 340 / f 300 |<2.8.

[0081] More specifically, in the embodiment, in the front group 100, the first lens 110 is a plano-convex lens or a meniscus lens, and the second lens 120, the third lens 130 and the fourth lens 140 are all meniscus lenses.

[0082] In the first power rear group 200, the fifth lens 210 is a double-concave lens, and the sixth lens 220, the seventh lens 230 and the eighth lens 240 are all double-convex lenses.

[0083] In the second power rear group 300, the ninth lens 310 is a double-concave lens, and the tenth lens 320, the eleventh lens 330 and the twelfth lens 340 are all double-convex lenses.

[0084] The splitting prism BS is a half-transmission half-reflection prism.

[0085] As a preferred embodiment, the second lens 120 and the third lens 130 are made of crown glass. The use of crown glass lens combination is more conducive to correcting the chromatic aberration of the system.

[0086] As shown in Figure 1 or Figure 2 The optical axes of the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 210, the sixth lens 220, the seventh lens 230 and the eighth lens 240 are all on the predetermined first optical axis (the dashed line transversely in Figure 1 The optical axes of the ninth lens 310, the tenth lens 320, the eleventh lens 330 and the twelfth lens 340 are all on the predetermined second optical axis (the dashed line longitudinally in Figure 1 The first optical axis and the second optical axis are perpendicular.

[0087] The center of the aperture of the first diaphragm S1 is on the first optical axis, and the center of the aperture of the second diaphragm S2 is on the second optical axis.

[0088] It should be noted that the magnification of the first magnification rear group 200 is smaller than the magnification of the second magnification rear group 300. In this embodiment, the first magnification rear group 200 is a small magnification rear group, and the second magnification rear group 300 is a large magnification rear group.

[0089] It can be understood that the aperture value of the diaphragm needs to be adjusted according to the specific application scenario.

[0090] In order to verify whether the above optical system meets the design purpose, the following is a specific test example given according to the above settings of this embodiment:

[0091] In this test example, the lens data of the measurement lens optical system composed of the front group 100 and the first magnification rear group 200 is shown in Table 1 as follows:

[0092] Table 1

[0093]

[0094]

[0095] It should be noted that in Table 1, the "front surface" corresponds to the left surface of the corresponding lens or lens group, and the "rear surface" corresponds to the right surface of the corresponding lens or lens group. Figure 1 Figure 1

[0096] ​​The lens data of the measurement lens optical system composed of the front group 100 and the second magnification rear group 300 is shown in Table 2 below:

[0097] Table 2

[0098]

[0099]

[0100] It should be noted that in Table 2, the "front surface" of each lens in the second magnification rear group 300 corresponds to the lower surface (or the left surface) of the corresponding lens or lens group in the second magnification rear group 300, Figure 1 the "rear surface" corresponds to the upper surface (or the right surface) of the corresponding lens or lens group in the second magnification rear group 300. Figure 5 Figure 1 Figure 5

[0101] In this test example, the combined focal length f 100 of the front group 100 is 119 mm; the focal length f 110 of the first lens 110 is 234 mm, the focal length f 120 of the second lens 120 is 221 mm, the focal length f U1 of the first cemented lens U1 is -89 mm; the combined focal length f 200 of the first magnification rear group 200 is 19 mm, the focal length f 230 of the seventh lens 230 is 32 mm, the focal length f 240 of the eighth lens 240 is 40 mm, the focal length f U2 of the second cemented lens U2 is -42 mm;

[0102] The combined focal length f 300 of the second magnification rear group 300 is 51 mm, the focal length f 330 of the eleventh lens 330 is 67 mm, the focal length f 340 of the twelfth lens 340 is 110 mm, the focal length f U3 of the third cemented lens U3 is -128 mm.

[0103] Substituting the above values into the respective relationships shows that they all satisfy the relevant relationships of the present embodiment, i.e.:

[0104] 1.5 < |f 110 / f 100 | < 2.5, 0.75 < |f 110 / f 120 | < 1.25, 0.5 < |f U1 / f 100 | < 0.75. ​​​

[0105] 1.4<|f 230 / f 200 |<3,1.2<|f 240 / f 200 |<2,1.5<|f U2 / f 200 |<2.5;

[0106] 1.6<|f U3 / f 300 |<2.6,2<|f 330 / f 300 |<3,1.8<|f 340 / f 300 |<2.8。

[0107] Please refer to Figures 6-9 , Figure 6 the MTF (Modulation Transfer Function) diagram of the small-magnification optical system provided by the embodiment of the application, Figure 7 the MTF diagram of the large-magnification optical system of the embodiment of the utility model, Figure 8 the distortion schematic diagram of the small-magnification optical system of the embodiment of the utility model, Figure 9 the distortion schematic diagram of the large-magnification optical system of the embodiment of the utility model.

[0108] In the example, the front group 100 and the first-magnification rear group 200 form a small-magnification measurement lens optical system, and the optical parameters are shown in Table Three as follows:

[0109] Table Three

[0110]

[0111] In the example, the front group 100 and the second-magnification rear group 300 form a large-magnification measurement lens optical system, and the optical parameters are shown in Table Four as follows:

[0112] Table Four

[0113] Working distance WD 150 mm Magnification 0.44 times Field of view Φ 40 mm Target surface 1.1 inch MTF 30 > 140 lp / mm Telecentricity <0.02° Distortion <0.03％

[0114] In summary, the optical system of the dual-view measurement lens is realized through the above structure, the structure is compact, the length size can be effectively compressed, two magnifications, 0.16 times and 0.44 times, respectively, can connect two cameras to detect at the same time, realize large field of view and small field of view measurement at the same time, improve the precision, shorten the measurement time, and improve the test efficiency.

[0115] Embodiment Two

[0116] The embodiment provides a dual-view measurement lens, comprising an optical system of a dual-view measurement lens as described in the first embodiment.

[0117] Based on the detailed description of the optical system in the above embodiment, the embodiment will not be described again.

[0118] In conclusion, the dual-view measurement lens is realized by the above structure, the structure is compact, the length size can be effectively compressed, two magnifications are provided, the magnifications are 0.16 times and 0.44 times respectively, two cameras can be connected to simultaneously detect, large and small fields of view can be simultaneously measured, the appearance size or the overall shape of the target object can be enlarged and quickly captured by the large-view camera, the position requiring fine shape and precision is switched to the small-view camera to measure, and thus the measurement time can be shortened while the precision is improved.

[0119] The above embodiment is only used to illustrate the technical solutions of the present application, rather than limit the present application; although the present application is described in detail with reference to the above embodiment, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced by the equivalent; and the modification or replacement does not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical system of a dual field measuring lens, characterized by, The front group (100) with positive focal length, the light splitting prism and the rear group are sequentially arranged from the object side to the image side; The front group (100) is composed of a first lens (110) with positive focal length, a second lens (120) with positive focal length, a third lens (130) with positive focal length and a fourth lens (140) with negative focal length; wherein the third lens (130) and the fourth lens (140) form a first cemented lens with negative focal length; The rear group is composed of a first magnification rear group (200) with positive focal length arranged on the refractive path of the light splitting prism and a second magnification rear group (300) with positive focal length arranged on the reflection path of the light splitting prism; A first diaphragm is arranged between the first magnification rear group (200) and the light splitting prism, and the first diaphragm is arranged at the combined focal length of the front group (100) on the refractive path; a second diaphragm is arranged between the second magnification rear group (300) and the light splitting prism, and the second diaphragm is arranged at the combined focal length of the front group (100) on the reflection path; The first magnification rear group (200) is composed of a fifth lens (210) with negative focal length, a sixth lens (220) with positive focal length, a seventh lens (230) with positive focal length and an eighth lens (240) with positive focal length sequentially arranged from the first diaphragm to the first image surface; wherein the fifth lens (210) and the sixth lens (220) form a second cemented lens with negative focal length; The combined focal length of the first magnification rear group (200) is f 200 , the focal length of the second cemented lens is f U2 , the focal length of the seventh lens (230) is f 230 , and the focal length of the eighth lens (240) is f 240 ; f 230 and f 200 satisfies the relationship: 1.4 < |f 230 f 200 | < 3; f 240 and f 200 satisfies the relationship: 1.2 < |f 240 / f 200 | < 2; f U2 and f 200 satisfies the relation: 1.5 < |f U2 / f 200 < 2.5; The second magnification rear group (300) is composed of a ninth lens (310) with negative focal length, a tenth lens (320) with positive focal length, an eleventh lens (330) with positive focal length and a twelfth lens (340) with positive focal length sequentially arranged from the second diaphragm to the second image surface; wherein the ninth lens (310) and the tenth lens (320) form a third cemented lens with negative focal length; The combined focal length of the second-magnification group (300) is f 300 , the focal length of the third cemented lens is f U3 , the focal length of the eleventh lens (330) is f 330 , the focal length of the twelfth lens (340) is f 340 ; f U3 and f 300 satisfies the relationship: 1.6 < |f U3 / f 300 | < 2.6; f 330 and f 300 satisfy the relation: 2<|f 330 / f 300 |<3; f 340 and f 300 satisfies the relationship: 1.8 < |f 340 / f 300 | < 2.

8.

2. The optical system of a dual field measurement lens according to claim 1, wherein, The combined focal length of the front group (100) is f 100 The focal length of the first lens (110) is f 110 The focal length of the second lens 120 is f 120 The focal length of the first cemented lens is f U1 ; f 110 and f 100 satisfies the relation: 1.5 < |f 110 / f 100 | < 2.5; f 110 and f 120 satisfies the relation: 0.75 < |f 110 / f 120 | < 1.25; f U1 and f 100 satisfies the relation: 0.5<|f U1 / f 100 |<0.

75.

3. The optical system of a dual field measurement lens according to claim 1, wherein, In the front group (100), the first lens (110) is a plano-convex lens or a meniscus lens, and the second lens (120), the third lens (130) and the fourth lens (140) are all meniscus lenses; In the first magnification rear group (200), the fifth lens (210) is a double-concave lens, and the sixth lens (220), the seventh lens (230) and the eighth lens (240) are all double-convex lenses; In the second magnification rear group (300), the ninth lens (310) is a double-concave lens, and the tenth lens (320), the eleventh lens (330) and the twelfth lens (340) are all double-convex lenses.

4. The optical system of a dual field measurement lens according to claim 1, wherein, The light splitting prism is a half-transmission half-reflection prism.

5. The optical system of a dual field measurement lens according to claim 1, wherein, The materials of the second lens (120) and the third lens (130) are crown glass.

6. The optical system of a dual field measuring lens according to claim 1, wherein The optical axes of the first lens (110), the second lens (120), the third lens (130), the fourth lens (140), the fifth lens (210), the sixth lens (220), the seventh lens (230) and the eighth lens (240) are all on a predetermined first optical axis; Optical axes of the ninth lens (310), the tenth lens (320), the eleventh lens (330) and the twelfth lens (340) are on a predetermined second optical axis; the first optical axis and the second optical axis are perpendicular; An aperture center of the first diaphragm is on the first optical axis, and an aperture center of the second diaphragm is on the second optical axis.

7. The optical system of a dual field measurement lens according to claim 1, wherein, The first magnification rear group (200) has a magnification smaller than a magnification of the second magnification rear group (300).

8. A dual field measuring lens characterized by comprising: An optical system comprising a dual field measurement lens as claimed in any one of claims 1-7.

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