Dispersion-compensated objective assembly and device, spectral confocal interferometric system and method

Abstract

The application relates to a dispersion compensation objective lens assembly and device, a spectral confocal interference system and a method, wherein the dispersion compensation objective lens assembly comprises seven lenses coaxially arranged, and the seven lenses are a first negative lens, a first positive lens, a second positive lens, a second negative lens, a third positive lens, a fourth positive lens and a positive meniscus lens in sequence; the first negative lens and the first positive lens are cemented into a first cemented lens, and the second positive lens and the second negative lens are cemented into a second cemented lens; the materials of at least two lenses are different, and the materials of any two lenses satisfy the following constraint condition: Delta P ij / Delta V ij <= 0.0006. The dispersion compensation objective lens assembly provided by the application only uses one meniscus lens, thereby reducing the assembly difficulty and the manufacturing cost of the dispersion compensation objective lens assembly, and solving the problem of high assembly difficulty of the existing dispersion compensation objective lens.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging, in particular to a dispersion compensation objective assembly and device, a spectral confocal interference system and method. BACKGROUND

[0002] The spectral confocal interference technology is a non-contact optical measurement method combining the spectral interference technology and the color confocal microscope technology, and can realize accurate measurement of the three-dimensional surface topography and optical characteristics of a sample. The measurement arm in the spectral confocal interference system is mainly used for collecting the light signal reflected by the surface of the sample, and the reference arm is mainly used for introducing the interference effect. By comparing the optical path difference of the sample arm with the reference arm, the interference signal is obtained, so that the accurate measurement of the surface topography and optical characteristics of the sample is realized. The dispersion of the reference arm in the spectral confocal interference system has a great influence on the interference signal. For example, the dispersion can broaden the envelope of the interference signal, reduce the contrast of the interference signal, make the interference signal asymmetric, change the period of the interference signal, and reduce the axial resolution of the interference system. Therefore, the dispersion of the reference arm needs to be compensated to match the dispersion of the two arms. The dispersion compensation can be realized by a dispersion compensation objective. By specific optical design and material selection, the light of different wavelengths can be focused on the same focal point after passing through the dispersion compensation objective, so as to effectively reduce or eliminate the chromatic aberration. Therefore, the performance of the dispersion compensation objective determines the accuracy, longitudinal resolution and measurement range of the measurement system to some extent.

[0003] In order to obtain good imaging quality, the existing dispersion compensation objective usually uses a plurality of meniscus lenses (the meniscus lens referred to in the present application is a lens with a curvature radius of two walls less than 30 mm). The meniscus lens is difficult to process and relatively thin, and the meniscus lens is easy to break during the assembly of the dispersion compensation objective, which greatly increases the assembly difficulty of the dispersion compensation objective.

[0004] At present, there is no effective solution to the problem of high assembly difficulty of the existing dispersion compensation objective. SUMMARY

[0005] In the present application, a dispersion compensation objective assembly and device, a spectral confocal interference system and method are provided to solve the problem of high assembly difficulty of the existing dispersion compensation objective.

[0006] In a first aspect, a dispersion compensation objective assembly is provided in the present application, which comprises seven lenses coaxially arranged, and the seven lenses are sequentially a first negative lens, a first positive lens, a second positive lens, a second negative lens, a third positive lens, a fourth positive lens and a positive meniscus lens.

[0007] The first negative lens and the first positive lens are cemented together to form a first cemented lens, and the second positive lens and the second negative lens are cemented together to form a second cemented lens;

[0008] The materials of at least two of the lenses are different and the materials of any two of the lenses satisfy the following constraints:

[0009] ΔP ij / ΔV ij ≤0.0006

[0010] Where ΔP ij The difference in the material partial dispersion coefficient between the i-th lens and the j-th lens, ΔV ij Represents the material Abbe number difference between the i-th lens and the j-th lens.

[0011] In a second aspect, the present invention provides a dispersion compensation device, comprising a housing and a dispersion compensation objective lens assembly installed in the housing, wherein the dispersion compensation objective lens assembly is the dispersion compensation objective lens assembly described in the first aspect.

[0012] In a third aspect, the present invention provides a spectral confocal interference system, comprising a reference arm for introducing an interference effect and a dispersion compensating objective lens assembly for performing dispersion compensation on the reference arm, wherein the dispersion compensating objective lens assembly is the dispersion compensating objective lens assembly described in the first aspect.

[0013] In a fourth aspect, the present invention provides a spectral confocal interference system, comprising a reference arm for introducing an interference effect and a dispersion compensation device for performing dispersion compensation on the reference arm, wherein the dispersion compensation device is the dispersion compensation device described in the second aspect.

[0014] In a fifth aspect, the present invention provides a spectral confocal interference method, which performs dispersion compensation on a reference arm through the dispersion compensation objective lens assembly described in the first aspect or the dispersion compensation device described in the second aspect.

[0015] Compared with the related art, the dispersion-compensating objective lens assembly provided by the present invention uses only one meniscus lens. Compared with the existing dispersion-compensating objective lens assembly, the number of meniscus lenses is reduced, thereby reducing the assembly difficulty and manufacturing cost of the dispersion-compensating objective lens assembly, and solving the problem of the high assembly difficulty of the existing dispersion-compensating objective lens.

[0016] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1is a structural diagram of a dispersion compensation objective lens assembly provided in an embodiment of the present invention;

[0018] Figure 2 is a diagram illustrating the imaging principle of a dispersion compensation objective lens assembly provided in an embodiment of the present invention;

[0019] Figure 3 is an aberration dispersion pattern of the dispersion compensation objective lens assembly provided in an embodiment of the present invention;

[0020] Figure 4 is a chromatic focus shift diagram of the dispersion-compensating objective lens assembly provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical terms or scientific terms involved in this application should have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "an", "a", "the", "these" and the like in this application do not indicate quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "plurality" involved in this application refers to two or more. "And / or" describes the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. Generally, the character " / " indicates that the related objects are in an "or" relationship. The terms "first," "second," "third," etc. used in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0023] The present invention provides a dispersion compensation objective lens assembly, Figure 1 is a structural diagram of a dispersion compensation objective lens assembly provided in an embodiment of the present invention, Figure 2 Schematic diagram of light transmission of the dispersion compensation objective lens assembly provided in an embodiment of the present invention.

[0024] like Figure 1 and Figure 2 As shown, the dispersion compensation objective lens assembly includes seven lenses arranged coaxially, which are respectively a first negative lens 1, a first positive lens 2, a second positive lens 3, a second negative lens 4, a third positive lens 5, a fourth positive lens 6 and a positive meniscus lens 7.

[0025] The first negative lens 1 and the first positive lens 2 are cemented into a first cemented lens 10, and the second positive lens 3 and the second negative lens 4 are cemented into a second cemented lens 20; the third positive lens 5, the fourth positive lens 6 and the positive meniscus lens 7 are all single lenses.

[0026] The materials of at least two lenses are different and the materials of any two lenses satisfy the following constraints:

[0027] ΔP ij / ΔV ij ≤0.0006

[0028] Where ΔP ij The difference in the material partial dispersion coefficient between the i-th lens and the j-th lens, ΔV ij Represents the material Abbe number difference between the i-th lens and the j-th lens.

[0029] Specifically, the material partial dispersion coefficient P of the i-th lens is i The calculation formula is:

[0030]

[0031] Among them, n Fi 、n di 、n Ci They represent the refractive index of the material of the i-th lens under the characteristic light of F, d, and C respectively.

[0032] In the above technical solution, since the use of a single glass material cannot produce a good achromatic effect, a combination of at least two optical glass materials is required, so that the materials of at least two lenses are different. At the same time, the different materials are required to meet the above constraints. At this time, it can be ensured that the dispersion compensation objective lens assembly can better eliminate chromatic aberration.

[0033] In addition, the entire dispersion-compensating objective lens assembly uses only one meniscus lens, which reduces the number of meniscus lenses compared to existing dispersion-compensating objective lens assemblies, thereby reducing the assembly difficulty and manufacturing cost of the dispersion-compensating objective lens assembly, and solving the problem of the high assembly difficulty of existing dispersion-compensating objective lenses.

[0034] In some embodiments, the first negative lens 1 and the third positive lens 5 are both made of heavy crown glass with a refractive index between 1.90 and 1.96; the first positive lens 2 and the positive meniscus lens 7 are both made of fluorine crown glass with a refractive index between 1.45 and 1.50; the second positive lens 3, the second negative lens 4 and the fourth positive lens 6 are all made of lanthanum flint glass with a refractive index between 1.74 and 1.77.

[0035] In this embodiment, a total of three different types of materials are used for the different lenses. While the dispersion-compensating objective lens assembly is capable of effectively eliminating chromatic aberration, an excessive number of different types of materials are not used, thereby reducing the manufacturing difficulty of the dispersion-compensating objective lens assembly. Among them, the materials of the first negative lens 1 and the first positive lens 2 constituting the first cemented lens 10 are heavy crown glass and fluor crown glass, respectively, which is an optimal material combination and can reduce the manufacturing difficulty of the first cemented lens 10. At the same time, the materials of the second positive lens 3 and the second negative lens 4 constituting the second cemented lens 20 are both lanthanum flint glass, which is also an optimal material combination and can reduce the manufacturing difficulty of the second cemented lens 20. In summary, through the above-mentioned material selection, while the dispersion-compensating objective lens assembly is capable of effectively eliminating chromatic aberration, the manufacturing difficulty of the dispersion-compensating objective lens assembly is greatly reduced.

[0036] Based on the above embodiment, in a further embodiment, the center thickness of the first negative lens 1 is 2.5 mm, the center thickness of the first positive lens 2 is 4.2 mm, the center thickness of the second positive lens 3 is 4.3 mm, the center thickness of the second negative lens 4 is 8.2 mm, the center thickness of the third positive lens 5 is 4.4 mm, the center thickness of the fourth positive lens 6 is 5.5 mm, and the center thickness of the positive meniscus lens 7 is 3.4 mm. The air gap between the first cemented lens 10 and the second positive lens 3 is 0.5 mm; the air gap between the second cemented lens 20 and the third positive lens 5 is 13.9 mm; the air gap between the third positive lens 5 and the fourth positive lens 6 is 17.6 mm; and the air gap between the fourth positive lens 6 and the positive meniscus lens 7 is 5.5 mm. In the same reference direction, the curvature radii of the front and rear surfaces of the first negative lens 1 are -173.9 mm and 42.0 mm respectively, the curvature radii of the front and rear surfaces of the first positive lens 2 are 42.mm and -29 mm respectively, the curvature radii of the front and rear surfaces of the second positive lens 3 are 32.8 mm and -32.8 mm respectively, the curvature radii of the front and rear surfaces of the second negative lens 4 are -32.8 mm and -256.6 mm respectively, the curvature radii of the front and rear surfaces of the third positive lens 5 are -58.1 mm and -40.1 mm respectively, the curvature radii of the front and rear surfaces of the fourth positive lens 6 are 41.1 mm and 169.1 mm respectively, and the curvature radii of the front and rear surfaces of the positive meniscus lens 7 are 18.6 mm and 26.2 mm respectively.

[0037] In this embodiment, a specific structural parameter of a dispersion compensation objective lens assembly is specifically given. Among them, the air gap between lenses refers to the length of the air gap between two lenses, from the vertex of one lens to the vertex of the other lens. For example, referring to Figure 1 The air gap between the third positive lens 5 and the fourth positive lens 6 is the distance from the rightmost side of the third positive lens 5 to the leftmost side of the fourth positive lens 6.

[0038] The center thickness and curvature radius of each of the above lenses can be summarized as shown in Table 1.

[0039] Table 1 Summary of some parameters of dispersion compensation objective lens components

[0040]

[0041] The dispersion-compensating objective lens assembly can have a high chromatic aberration elimination performance by adopting the above parameters.

[0042] Specifically, the dispersion compensation objective lens assembly in the above embodiment has an operating wavelength range of 500-700 nm, and the imaging quality of each spectral component is good. Figure 3 As shown in FIG, three wavelengths of 500, 600 and 700 nm are set at equal intervals in the range of 500-700 nm, and the diffuse spots of each spectral component are smaller than the Airy disk.

[0043] Furthermore, the dispersion-compensating objective lens assembly in the above embodiment has an object distance greater than 85 mm, facilitating the integration of other optical components at the front end of the spectral confocal interferometer system. Furthermore, the distance from the rearmost lens surface to the image plane is greater than 20 mm, and the image-side numerical aperture is greater than 0.29, resulting in a large numerical aperture and high lateral resolution.

[0044] In summary, the dispersion compensation objective lens assembly in the above embodiment overcomes the imaging defects of a single lens to achieve the effect of achromatism in the wavelength range of 500-700nm, and plays a good dispersion compensation role in the spectral confocal interferometer system. Figure 4 As shown, the maximum focus displacement is 3.7149 μm in the wavelength range of 500-700 nm.

[0045] Specifically, compared with the existing dispersion-compensating objective lens assembly, the dispersion-compensating objective lens assembly provided by the present invention has the following advantages.

[0046] 1. The dispersion-compensating objective lens assembly provided by the present invention uses only one meniscus lens. Compared with the existing dispersion-compensating objective lens assembly, the number of meniscus lenses is reduced, thereby reducing the assembly difficulty and manufacturing cost of the dispersion-compensating objective lens assembly, and solving the problem of the high assembly difficulty of the existing dispersion-compensating objective lens.

[0047] 2、The application greatly reduces the manufacturing difficulty of the dispersion compensation objective lens assembly by optimizing the material selection and combination of different lenses on the basis of enabling the dispersion compensation objective lens assembly to eliminate chromatic aberration well.

[0048] 3、The numerical aperture is large, and the lateral resolution is high, and the image-side numerical aperture NA is greater than 0.29.

[0049] 4、The maximum focal point displacement is 3.7149 mu m, and achromatism of 500 nm to 700 nm waveband is realized, and the requirement of the dispersion compensation objective lens is met.

[0050] 5、The dispersion compensation objective lens has a long object distance, the object distance of the dispersion compensation objective lens is greater than 85 mm, the distance from the last surface of the lens to the image plane is greater than 20 mm, the front end optical path of the objective lens is convenient to adjust, and the dispersion compensation objective lens can be applied to different measurement systems, such as a spectral confocal interference measurement system.

[0051] In the application, a dispersion compensation device is also provided, which comprises a shell and a dispersion compensation objective lens assembly installed in the shell, and the dispersion compensation objective lens assembly is the dispersion compensation objective lens assembly provided in the application.

[0052] In the application, a spectral confocal interference system is also provided, which comprises a reference arm for introducing an interference effect and a dispersion compensation objective lens assembly or a dispersion compensation device for dispersion compensation of the reference arm, the dispersion compensation objective lens assembly is the dispersion compensation objective lens assembly provided in the application, and the dispersion compensation device is the dispersion compensation device provided in the application.

[0053] In the application, a spectral confocal interference method is also provided, and the spectral confocal interference method performs dispersion compensation on a reference arm through the dispersion compensation objective lens assembly provided in the application or the dispersion compensation device provided in the application.

[0054] It should be understood that the specific embodiments described herein are only used to explain this application, but not to limit it. According to the embodiments provided in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0055] Obviously, the drawings are only some examples or embodiments of the application, and the application can also be applied to other similar cases without creative labor according to the drawings for those skilled in the art. In addition, it can be understood that although the work done in the development process may be complex and long, some design, manufacture or production changes according to the technical content disclosed in the application are only conventional technical means for those skilled in the art, and should not be regarded as insufficient disclosure of the application.

Claims

1. A dispersion-compensating objective lens assembly, characterized in that: The dispersion compensation objective lens assembly includes seven lenses arranged coaxially, wherein the seven lenses are respectively a first negative lens, a first positive lens, a second positive lens, a second negative lens, a third positive lens, a fourth positive lens and a positive meniscus lens; The first negative lens and the first positive lens are cemented together to form a first cemented lens, and the second positive lens and the second negative lens are cemented together to form a second cemented lens; The materials of at least two of the lenses are different and the materials of any two of the lenses satisfy the following constraints: ΔP ij / ΔV ij ≤0.0006 Where ΔP ij The difference in the material partial dispersion coefficient between the i-th lens and the j-th lens, ΔV ij Represents the material Abbe number difference between the i-th lens and the j-th lens.

2. The dispersion-compensating objective lens assembly according to claim 1, wherein: The first negative lens and the third positive lens are both made of heavy crown glass and have a refractive index between 1.90 and 1.96; The first positive lens and the positive meniscus lens are both made of fluor-crown glass and have a refractive index between 1.45 and 1.50; The second positive lens, the second negative lens, and the fourth positive lens are all made of lanthanum flint glass, and their refractive indices are all between 1.74 and 1.

77.

3. The dispersion-compensating objective lens assembly according to claim 2, wherein: The center thickness of the first negative lens is 2.5 mm, the center thickness of the first positive lens is 4.2 mm, the center thickness of the second positive lens is 4.3 mm, the center thickness of the second negative lens is 8.2 mm, the center thickness of the third positive lens is 4.4 mm, the center thickness of the fourth positive lens is 5.5 mm, and the center thickness of the positive meniscus lens is 3.4 mm.

4. The dispersion-compensating objective lens assembly according to claim 3, wherein: The air gap between the first cemented lens and the second positive lens is 0.5 mm; And / or, the air gap between the second cemented lens and the third positive lens is 13.9 mm; And / or, the air gap between the third positive lens and the fourth positive lens is 17.6 mm; And / or, the air gap between the fourth positive lens and the positive meniscus lens is 5.5 mm.

5. The dispersion-compensating objective lens assembly according to claim 4, wherein: In the same reference direction, the curvature radii of the front surface and the back surface of the first negative lens are -173.9 mm and 42.0 mm respectively, the curvature radii of the front surface and the back surface of the first positive lens are 42.mm and -29 mm respectively, the curvature radii of the front surface and the back surface of the second positive lens are 32.8 mm and -32.8 mm respectively, the curvature radii of the front surface and the back surface of the second negative lens are -32.8 mm and -256.6 mm respectively, the curvature radii of the front surface and the back surface of the third positive lens are -58.1 mm and -40.1 mm respectively, the curvature radii of the front surface and the back surface of the fourth positive lens are 41.1 mm and 169.1 mm respectively, and the curvature radii of the front surface and the back surface of the positive meniscus lens are 18.6 mm and 26.2 mm respectively.

6. The dispersion-compensating objective lens assembly according to claim 5, wherein: The working wavelength band of the dispersion compensation objective lens assembly is 500-700nm.

7. A dispersion compensation device comprising a housing and a dispersion compensation objective lens assembly mounted in the housing, characterized in that: The dispersion-compensating objective lens assembly is the dispersion-compensating objective lens assembly according to any one of claims 1 to 6.

8. A spectral confocal interferometer system comprising a reference arm for introducing an interference effect and a dispersion compensation objective lens assembly for performing dispersion compensation on the reference arm, characterized in that: The dispersion-compensating objective lens assembly is the dispersion-compensating objective lens assembly according to any one of claims 1 to 6.

9. A spectral confocal interferometer system comprising a reference arm for introducing an interference effect and a dispersion compensation device for performing dispersion compensation on the reference arm, characterized in that: The dispersion compensation device is the dispersion compensation device according to claim 7.

10. A spectral confocal interferometry method, characterized in that: The spectral confocal interference method performs dispersion compensation on the reference arm through the dispersion compensation objective lens assembly described in any one of claims 1 to 6 or the dispersion compensation device described in claim 7.

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