Infinity conjugate microscope objective lens group

Abstract

The present invention provides an infinity conjugate microscope objective lens group, relating to the technical field of microscope objectives. The lens group includes: a first optical component, a second optical component, a third optical component, a fourth optical component, a fifth optical component, and a sixth optical component that are sequentially arranged from the object side to the image side and coaxially arranged; wherein, the first optical component, the second optical component, and the third optical component constitute a long working distance flat field apochromatic microscope objective, and the fourth optical component, the fifth optical component, and the sixth optical component constitute a sleeve lens; the long working distance flat field apochromatic microscope objective and the sleeve lens are combined to form the infinity conjugate microscope objective lens group, with a working distance up to 51 mm, having a simple structure and being easy to process. The distance between the long working distance flat field apochromatic microscope objective and the sleeve lens is adjustable within the range of 45 mm to 100 mm. The present invention can meet the requirements for microscope objectives in various fields.

Description

Technical Field

[0001] The present invention relates to the technical field of microscopic objectives, and particularly to an infinity conjugate microscopic objective lens group. Background Art

[0002] Long working distance plan apochromatic objectives are increasingly widely used in industries such as semiconductor, electronics, metallurgy, and biological microscopic imaging, and are widely used in various occasions such as semiconductor defect detection, microscopic biological sample observation, and laser repair.

[0003] At present, the general working distance of a high-definition long working distance 5x microscopic objective represented by Mitutoyo of Japan is 34 mm. However, in the actual industrial microscopic measurement field, there are higher requirements for the working distance, and the existing long working distance plan apochromatic objectives cannot meet such requirements. At the same time, to meet the high-precision measurement requirements such as long working distance plan apochromatism, the design of high-precision microscopic objectives is mostly complex and difficult to process. Summary of the Invention

[0004] In view of the above problems, the present invention provides an infinity conjugate microscopic objective lens group, which constitutes a complete system of a long working distance plan apochromatic objective and a sleeve lens through an optical lens group with a relatively simple structure. All the objective lenses of the present invention adopt spherical lenses, and have a simple structure and a reasonable design, and can be completely realized under the existing processing and inspection processes.

[0005] The infinity conjugate microscopic objective lens group provided by the present invention includes: a first optical component, a second optical component, a third optical component, a fourth optical component, a fifth optical component, and a sixth optical component that are sequentially arranged from the object side to the image side and arranged coaxially; wherein, the first optical component, the second optical component, and the third optical component constitute a long working distance plan apochromatic microscopic objective, and the fourth optical component, the fifth optical component, and the sixth optical component constitute a sleeve lens; the long working distance plan apochromatic microscopic objective and the sleeve lens are combined to form the infinity conjugate microscopic objective lens group, and the distance between the long working distance plan apochromatic microscopic objective and the sleeve lens is adjustable within the range of 45 mm to 100 mm.

[0006] According to an embodiment of the present invention, the first optical component includes a plano-convex lens with a positive optical power, the second optical component includes a first doublet lens with a positive optical power, and the third optical component includes a second doublet lens with a negative optical power, wherein: the first optical component and the second optical component are used to bear the positive optical power required by the long working distance flat-field apochromatic microscope objective and compensate for the negative optical power of the third optical component; the third optical component is used to compensate for the remaining aberrations of the first optical component and the second optical component and jointly form a retrofocus system with the first optical component and the second optical component, and the working distance of the retrofocus system is greater than the focal length.

[0007] According to an embodiment of the present invention, the sleeve lens is a Cooke-type objective lens with a focal length of 200 mm.

[0008] According to an embodiment of the present invention, the fourth optical component includes a biconvex lens with a positive optical power, the fifth optical component includes a biconcave lens with a negative optical power, and the sixth optical component includes a meniscus lens with a positive optical power.

[0009] According to an embodiment of the present invention, the side with the larger curvature radius of the plano-convex lens faces the object side, and it is made of H-ZPK1A material with a refractive index n = 1.618 and an Abbe number v = 63.406.

[0010] According to an embodiment of the present invention, the first doublet lens includes a biconvex lens and a plano-concave lens glued together, wherein: the biconvex lens is made of H-ZPK5 material with a refractive index n = 1.5928 and an Abbe number v == 68.525; the plano-concave lens is made of H-F1 material with a refractive index n = 1.6034 and an Abbe number v = 38.009.

[0011] According to an embodiment of the present invention, the second doublet lens includes a plano-convex lens and a biconcave lens glued together, wherein: the plano-convex lens is made of D-ZF93 material with a refractive index n = 2.0017 and an Abbe number v = 20.705; the biconcave lens is made of H-F1 material with a refractive index n = 1.6034 and an Abbe number v = 38.009.

[0012] According to an embodiment of the present invention, the side with the larger radius of curvature in the biconvex lens faces the image side, and the side with the smaller radius of curvature faces the object side. It is made of H-ZK7A material, with a refractive index n = 1.6131 and an Abbe number v = 60.384. In the biconcave lens, the side with the larger radius of curvature faces the object side, and the side with the smaller radius of curvature faces the image side. It is made of TF3 material, with a refractive index n = 1.6124 and an Abbe number v = 44.093. In the meniscus lens, the side with the larger radius of curvature faces the object side, and the convex side faces the image side. It is made of H-ZK21 material, with a refractive index n = 1.623 and an Abbe number v = 58.154.

[0013] According to an embodiment of the present invention, the magnification of the long working distance planachromat microscope objective lens is 5 times, the numerical aperture is 0.14, and the working distance is 51 mm.

[0014] Compared with the prior art, the infinity conjugate microscope objective lens group provided by the present invention has at least the following beneficial effects:

[0015] (1) The long working distance planachromat objective lens provided by the present invention, in cooperation with the sleeve lens, can meet the requirements for microscope objectives in various fields.

[0016] (2) The long working distance planachromat objective lens provided by the present invention uses all spherical lenses, which can be completely realized under the existing processing and inspection processes. It has a simple structure, reasonable design, high clarity in the entire field of view, a longer working distance, a wider wavelength band, and expands the application requirements for precision measurement.

[0017] (3) The infinity conjugate microscope objective lens group provided by the present invention is applicable to the field of high-precision industrial microscopic measurement and meets the application requirements of long working distance, high clarity, and small distortion in industrial microscopic measurement. Description of the Drawings

[0018] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0019] Figure 1 Schematically shows the structural diagram of the infinity conjugate microscope objective lens group according to an embodiment of the present invention;

[0020] Figure 2 Schematically shows the field curvature and distortion diagram of the long working distance planachromat microscope objective lens according to an embodiment of the present invention, where (a) is the field curvature diagram and (b) is the distortion diagram;

[0021] Figure 3 Schematically shows the chromatic aberration curve diagram of the long working distance planachromat microscope objective lens according to an embodiment of the present invention;

[0022] Figure 4 Schematically illustrates a spot diagram of a long working distance plan apochromatic microscope objective according to an embodiment of the present invention;

[0023] Figure 5 The MTF curve of the long working distance plan apochromatic microscope objective according to an embodiment of the present invention is schematically shown.

[0024] [Description of Reference Numerals]

[0025] 1-first optical component; 2-second optical component; 3-third optical component; 4-fourth optical component; 5-fifth optical component; 6-sixth optical component. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0028] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to direct connection or indirect connection through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0029] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0030] Figure 1 The structure of an infinite conjugate microscope objective lens assembly according to an embodiment of the present invention is schematically shown.

[0031] like Figure 1As shown in the figure, the infinity conjugate microscope objective lens group according to this embodiment includes: a first optical component 1, a second optical component 2, a third optical component 3, a fourth optical component 4, a fifth optical component 5, and a sixth optical component 6, which are sequentially arranged from the object side to the image side and coaxially arranged.

[0032] Among them, the first optical component 1, the second optical component 2, and the third optical component 3 constitute a long working distance flat field apochromatic microscope objective, and the fourth optical component 4, the fifth optical component 5, and the sixth optical component 6 constitute a sleeve lens.

[0033] The long working distance flat field apochromatic microscope objective and the sleeve lens are combined to form an infinity conjugate microscope objective lens group, and the distance between the long working distance flat field apochromatic microscope objective and the sleeve lens is adjustable within the range of 45 mm to 100 mm.

[0034] Through the above embodiment, the infinity conjugate microscope objective lens group provided by the present invention is formed by combining a long working distance flat field apochromatic microscope objective and a sleeve lens, has a long working distance, good flat field apochromatic correction effect, the distance from the sleeve lens to the microscope objective is adjustable, and the structure is relatively simple, which can meet the requirements of microscope objectives in various fields.

[0035] Specifically, the first optical component 1 includes a plano-convex lens with a positive optical power, the second optical component 2 includes a first doublet lens with a positive optical power, and the third optical component 3 includes a second doublet lens with a negative optical power. Among them, the first optical component 1 and the second optical component 2 are used to bear the positive optical power required by the long working distance flat field apochromatic microscope objective and compensate for the negative optical power of the third optical component 3. The third optical component 3 is used to compensate for the remaining aberrations of the first optical component 1 and the second optical component 2, and together with the first optical component 1 and the second optical component 2, they constitute a retrofocus system, and the working distance of the retrofocus system is greater than the focal length.

[0036] The fourth optical component 4, the fifth optical component 5, and the sixth optical component 6 constitute a sleeve lens, and this sleeve lens is a Cooke-type objective lens with a focal length of 200 mm.

[0037] Specifically, the fourth optical component 4 includes a double convex lens with a positive optical power, the fifth optical component 5 includes a double concave lens with a negative optical power, and the sixth optical component 6 includes a meniscus lens with a positive optical power.

[0038] Since the intervals between the fourth optical component 4 and the fifth optical component 5, and between the fifth optical component 5 and the sixth optical component 6 are both large, in the sleeve lens, the separation of the positive and negative optical powers results in a large linear field of view of the sleeve lens, OPN = 24 mm.

[0039] Furthermore, the beam between the sleeve lens and the microscope objective is highly collimated, ensuring high clarity across the entire field of view and forming a flat-field objective.

[0040] Please continue to refer to Figure 1 , when the first optical component 1 is specifically a plano-convex lens with a positive optical power, the side with the larger radius of curvature (i.e., the plane) in this plano-convex lens faces the object side, is made of H-ZPK1A material, with a refractive index n = 1.618 and an Abbe number v = 63.406.

[0041] When the second optical component 2 is specifically a first doublet lens with a positive optical power, this first doublet lens includes a biconvex lens and a plano-concave lens glued together. Among them, the biconvex lens is made of H-ZPK5 material, with a refractive index n = 1.5928 and an Abbe number v = 68.525. The plano-concave lens is made of H-F1 material, with a refractive index n = 1.6034 and an Abbe number v = 38.009. Thus, the first optical component 1 and the second optical component 2 not only undertake all the positive optical power required for the long working distance flat-field apochromatic microscope objective, but also compensate for the negative optical power of the third optical component 3.

[0042] When the third optical component 3 is specifically a second doublet lens with a negative optical power, this second doublet lens includes a plano-convex lens and a biconcave lens glued together. Among them, the plano-convex lens is made of D-ZF93 material, with a refractive index n = 2.0017 and an Abbe number v = 20.705. The biconcave lens is made of H-F1 material, with a refractive index n = 1.6034 and an Abbe number v = 38.009.

[0043] Through the above embodiments, the third optical component 3 in the present invention not only compensates for the remaining aberrations of the first optical component 1 and the second optical component 2, but also together with the first optical component 1 and the second optical component 2 with positive optical power constitutes a retrofocus system, and the working distance of the retrofocus system is greater than the focal length. Specifically, in this retrofocus system, the retrofocus coefficient (i.e., the working distance divided by the focal length) can reach 1.27. This feature enables the long working distance flat-field apochromatic microscope objective to have high clarity of flat-field apochromatism while significantly increasing the working distance.

[0044] When the fourth optical component 4 is a biconvex lens with a positive optical power, the side with the larger radius of curvature in this biconvex lens faces the image side (e.g., Figure 1 the right side in Figure 1 ), and the side with the smaller radius of curvature faces the object side (e.g.,

[0045] Meanwhile, when the fifth optical component 5 is a biconcave lens with a negative optical power, the surface with a larger radius of curvature in the biconcave lens faces the object side, and the surface with a smaller radius of curvature faces the image side. The biconcave lens is made of TF3 material, with a refractive index n = 1.6124 and an Abbe number v = 44.093.

[0046] When the sixth optical component 6 is a meniscus lens with a positive optical power, the surface with a larger radius of curvature in the meniscus lens faces the object side, and the convex surface faces the image side. The meniscus lens is made of H-ZK21 material, with a refractive index n = 1.623 and an Abbe number v = 58.154.

[0047] The following Table 1 summarizes the detailed data of the radius of curvature R, central thickness, refractive index n, and Abbe number v of each lens in the above embodiments.

[0048] Table 1

[0049]

[0050] It should be noted that in Table 1, INFINITY in the radius of curvature R indicates an infinite plane. For example, if the first optical component 1 is a plano-convex lens with a positive optical power, the surface facing the object side (e.g., Figure 1 the left side in ) is a plane, so the previous radius of curvature R of the first optical component 1 in Table 1 is represented as INFINITY.

[0051] Based on the above disclosure, combined with the optical software ZEMAX, a long working distance planapochromatic microscope objective with a magnification of 5 times, a numerical aperture of 0.14, and good imaging quality can be obtained, and its working distance is 51 mm.

[0052] Figure 2 Schematically shows the field curvature and distortion diagram of the long working distance planapochromatic microscope objective according to an embodiment of the present invention, where (a) is the field curvature diagram and (b) is the distortion diagram.

[0053] As Figure 2 It can be seen that the field curvature < 0.05 mm and the distortion < 0.2%, indicating that the long working distance planapochromatic microscope objective of the embodiment of the present invention effectively ensures good flat field performance.

[0054] Figure 3 Schematically shows the chromatic aberration curve diagram of the long working distance planapochromatic microscope objective according to an embodiment of the present invention.

[0055] As Figure 3It can be seen that in the (F, d, C) visible light band, apochromatism is achieved, and the axial aberration of the short-wavelength g-line (0.436 μm line) is small. There is an obvious high-order amount of spherical aberration, making the spherical aberration curve closely adhere to the vertical axis as a whole, and good image quality is obtained.

[0056] Figure 4 Schematically shows the spot diagram of the long working distance plan apochromatic microscopic objective lens according to an embodiment of the present invention.

[0057] As Figure 4 It can be seen that the blur spots at 0, 0.707 and 1 fields of view (full field of view) are all uniformly smaller than the Airy disk (diffraction limit), and the energy is very concentrated.

[0058] Figure 5 Schematically shows the MTF curve diagram of the long working distance plan apochromatic microscopic objective lens according to an embodiment of the present invention.

[0059] As Figure 5 It can be seen that the modulation transfer function (MTF) of each field of view uniformly approaches the diffraction limit, indicating that the system has good transmission performance for signals of different spatial frequencies.

[0060] Through the above embodiments, it can be Figures 2 - 5 known that the design of the long working distance plan apochromatic microscopic objective lens is close to the diffraction limit and meets the design requirements. Thus, the infinity conjugate microscopic objective lens group provided by the present invention is applicable to the field of high-precision industrial microscopic measurement, and meets the application requirements of long working distance, high definition, and small distortion in industrial microscopic measurement.

[0061] From the above description, it can be seen that the infinity conjugate microscopic objective lens group provided by the above embodiments of the present invention is formed by combining a long working distance plan apochromatic microscopic objective lens and a sleeve lens, and at least achieves the following technical effects:

[0062] (1) Long working distance; using a retrofocus structure, the working distance is up to 51 mm, far exceeding the 34 mm working distance of ordinary Mitutoyo microscopic lenses, and can be used for microscopes in the field of precision measurement;

[0063] (2) Good plan apochromatic correction effect; the maximum remaining aberration of the lens at the 0.707 field of view is <1 μm, the geometric aberration can be corrected within 1 times the Airy disk, and the blur spot (SPT) <1 DL (Diffraction Limited);

[0064] (3) The distance between the sleeve lens and the microscopic objective lens is adjustable; the distance between the sleeve lens and the microscopic objective lens is adjustable within the range of 45 - 100 mm;

[0065] (4) The structure is relatively simple; the structure of the microscope objective lens and the sleeve lens is simple. The microscope objective lens uses 5 lenses, and the sleeve lens uses 3 lenses. The 4th and 5th lenses of the objective lens adopt H-ZPK5 material, using two pieces of heavy phosphate crown glass (ZPK), which can correct the secondary spectrum and achieve apochromatism.

[0066] (5) The applicable wavelength band is extended; it is extended from the commonly used visible light wavelength bands (F, d, C) to the blue-violet g line (0.436μm) close to the ultraviolet.

[0067] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. When it may cause confusion in the understanding of the present invention, the conventional structure or construction will be omitted. And the shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual sizes, ratios, and actual positional relationships.

[0068] Similarly, in order to streamline the present invention and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0069] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined. In addition, the word "a" or "an" before an element does not exclude the existence of a plurality of such elements. Unless otherwise stated, the expressions "about", "approximately", "substantially", and "around" mean within 10%, preferably within 5%.

[0070] The specific embodiments described above further elaborate on the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An infinity conjugate microscope objective lens group, characterized in that, Comprising: A first optical component (1), a second optical component (2), a third optical component (3), a fourth optical component (4), a fifth optical component (5), and a sixth optical component (6) that are sequentially arranged from the object side to the image side and coaxially arranged; Among them, the first optical component (1), the second optical component (2), and the third optical component (3) constitute a long working distance planachromatic apochromatic microscope objective, and the fourth optical component (4), the fifth optical component (5), and the sixth optical component (6) constitute a sleeve lens; The long working distance planachromatic apochromatic microscope objective and the sleeve lens are combined to form the infinity conjugate microscope objective group, and the distance between the long working distance planachromatic apochromatic microscope objective and the sleeve lens is adjustable within the range of 45 mm to 100 mm; The first optical component (1) includes a plano-convex lens with a positive focal power, the second optical component (2) includes a first doublet lens with a positive focal power, and the third optical component (3) includes a second doublet lens with a negative focal power, where: The first optical component (1) and the second optical component (2) are used to bear the positive focal power required by the long working distance planachromatic apochromatic microscope objective and compensate for the negative focal power of the third optical component (3); The third optical component (3) is used to compensate for the remaining aberrations of the first optical component (1) and the second optical component (2), and together with the first optical component (1) and the second optical component (2), constitutes a retrofocus system, and the working distance of the retrofocus system is greater than the focal length.

2. The infinity conjugate microscopic objective lens group according to claim 1, wherein The sleeve lens is a Cooke-type objective lens with a focal length of 200 mm.

3. The infinity conjugate microscopic objective lens group according to claim 1, characterized in that, The fourth optical component (4) includes a biconvex lens with a positive focal power, the fifth optical component (5) includes a biconcave lens with a negative focal power, and the sixth optical component (6) includes a meniscus lens with a positive focal power.

4. The infinity conjugate microscopic objective lens group according to claim 1, characterized in that, The side with the larger curvature radius of the plano-convex lens faces the object side, and it is made of H-ZPK1A material, with a refractive index n = 1.618 and an Abbe number v = 63.

406.

5. The infinity conjugate microscopic objective lens group according to claim 1, characterized in that The first doublet lens includes a biconvex lens and a plano-concave lens glued together, where: The biconvex lens is made of H-ZPK5 material, with a refractive index n = 1.5928 and an Abbe number v = 68.525; The plano-concave lens is made of H-F1 material, with a refractive index n = 1.6034 and an Abbe number v = 38.

009.

6. The infinity conjugate microscopic objective lens group according to claim 1, characterized in that, The second doublet lens includes a plano-convex lens and a biconcave lens glued together, where: The plano-convex lens is made of D-ZF93 material, with a refractive index n = 2.0017 and an Abbe number v = 20.705; The biconcave lens is made of H-F1 material, with a refractive index n = 1.6034 and an Abbe number v = 38.

009.

7. The infinity conjugate microscopic objective lens group according to claim 3, characterized in that, The side with the larger curvature radius of the biconvex lens faces the image side, and the side with the smaller curvature radius faces the object side, and it is made of H-ZK7A material, with a refractive index n = 1.6131 and an Abbe number v = 60.384; The side with a larger radius of curvature in the biconcave lens faces the object side, and the side with a smaller radius of curvature faces the image side. It is made of TF3 material, with a refractive index n = 1.6124 and an Abbe number v = 44.093; The side with a larger radius of curvature in the meniscus lens faces the object side, and the convex side faces the image side. It is made of H-ZK21 material, with a refractive index n = 1.623 and an Abbe number v = 58.

154.

8. The infinity conjugate microscopic objective lens group according to claim 1, characterized in that, The magnification of the long working distance planapochromatic microscope objective is 5 times, the numerical aperture is 0.14, and the working distance is 51 mm.

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