Microscope objective and optical system of a microscope objective

Abstract

The application relates to a microscope objective and an optical system of the microscope objective, the optical system of the microscope objective comprising a first lens group with positive refractive power, a second lens group with positive refractive power and a third lens group with positive or negative refractive power arranged in sequence from an object side to an image side; the first lens group comprises at least one and more than one optical element with positive refractive power, the second lens group comprises at least two and more than two optical elements with positive refractive power, and the Abbe number of the material of the optical elements is greater than a first threshold value. The optical system of the microscope objective can work in the whole waveband by setting the Abbe number of the material of the optical elements in the first lens group and the second lens group; the first lens group, the second lens group and the third lens group are arranged to make the optical system of the microscope objective have high resolution, realize chromatic aberration correction in the whole waveband of visible light, and meanwhile keep the characteristics of small field curvature and small distortion.

Description

Technical Field

[0001] This application relates to the field of microscopy technology, and more particularly to a microscope objective and an optical system for the microscope objective. Background Technology

[0002] In the field of microscopy, in addition to visual observation using eyepieces, the use of digital cameras to acquire microscope images for observation and analysis is expanding significantly. In recent years, the demand for high-resolution, wide-field-of-view, and large-aperture microscope objectives has been increasing. Existing microscopes with normal apochromatic function have a magnification of 20, a numerical aperture (NA) of 0.75, an object-side field of view of 1.25 mm, and a working distance of 0.677 mm. However, these microscopes suffer from insufficient numerical aperture, low resolution, insufficient working distance, and a narrow working wavelength, resulting in low resolution and significant distortion. Summary of the Invention

[0003] This application provides a microscope objective and an optical system for the microscope objective, which solves the technical problems of existing microscopes, such as insufficient numerical aperture, insufficient resolution, insufficient working distance, and insufficient working wavelength.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] On the one hand, an optical system for a microscope objective is provided, comprising a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having positive or negative refractive power arranged sequentially from the object side to the image side.

[0006] The first lens group includes at least one or more optical elements with positive refractive power, and the second lens group includes at least two or more optical elements with positive refractive power, wherein the material of the optical elements has an Abbe number greater than a first threshold.

[0007] Preferably, the ratio of the focal distance of the first lens group to the focal distance of the optical system is greater than a second threshold and less than a third threshold; the ratio of the focal distance of the second lens group to the focal distance of the optical system is greater than a fourth threshold and less than a fifth threshold; the ratio of the focal distance of the third lens group to the focal distance of the optical system is greater than a sixth threshold and less than a seventh threshold; and the ratio of the length formed by the first lens group, the second lens group, and the third lens group to the focal distance of the optical system is greater than an eighth threshold and less than a ninth threshold.

[0008] Preferably, the second threshold is 0.9, the third threshold is 1.2, the fourth threshold is 7.0, the fifth threshold is 15.0, the sixth threshold is -30, the seventh threshold is 40, the eighth threshold is 5.0, and the ninth threshold is 5.8.

[0009] Preferably, the ratio of the distance from the object side to the first lens group to the focal distance of the optical system is less than a tenth threshold; the ratio of the distance from the first lens group to the second lens group to the focal distance of the optical system is less than an eleventh threshold; and the ratio of the distance from the second lens group to the third lens group to the focal distance of the optical system is less than a twelfth threshold.

[0010] Preferably, the tenth threshold is 0.12, the eleventh threshold is 0.4, and the twelfth threshold is 0.3.

[0011] Preferably, the first threshold is 70.

[0012] Preferably, the first lens group includes a first optical element with negative refractive power, a second optical element with positive refractive power, and a third optical element with positive refractive power arranged sequentially from the object side to the image side; and / or, the second lens group includes a fourth optical element with positive refractive power and a fifth optical element with negative refractive power arranged sequentially from the object side to the image side; and / or, the third lens group includes a sixth optical element with negative refractive power and a seventh optical element with positive refractive power arranged sequentially from the object side to the image side.

[0013] Preferably, the first optical element is a lens or a first cemented lens, the second optical element is a lens, and the third optical element is a lens or a first cemented lens; and / or, the fourth optical element is a second cemented lens, and the fifth optical element is a first cemented lens; and / or, the sixth optical element is a first cemented lens, and the seventh optical element is a lens.

[0014] Preferably, the first cemented lens is a cemented lens composed of two lenses; and / or, the second cemented lens is a cemented lens composed of two or more lenses.

[0015] On the other hand, a microscope objective is provided, comprising an optical system of the microscope objective described above, wherein the distortion of the microscope objective is controlled within -1% to 1%.

[0016] The microscope objective and its optical system include a first lens group with positive refractive power, a second lens group with positive refractive power, and a third lens group with positive or negative refractive power arranged sequentially from the object side to the image side; the first lens group includes at least one or more optical elements with positive refractive power, and the second lens group includes at least two or more optical elements with positive refractive power, wherein the material of the optical elements has an Abbe number greater than a first threshold.

[0017] As can be seen from the above technical solutions, this application has the following advantages: the optical system of the microscope objective can work across the entire wavelength range by setting the Abbe number of the optical element materials in the first and second lens groups; the arrangement of the first, second, and third lens groups enables the optical system of the microscope objective to have high resolution, achieve chromatic aberration correction across the entire visible light wavelength range, and maintain the characteristics of small field curvature and small distortion; it solves the technical problems of existing microscopes, such as insufficient numerical aperture, insufficient resolution, insufficient working distance, and too small working wavelength range.

[0018] This microscope objective achieves a long working distance with a large numerical aperture by limiting the focal distances of the first, second, and third lens groups, while using fewer lenses and initially correcting spherical aberration, field curvature, and distortion. Further aberration correction is achieved by limiting the spacing between the first, second, and third lens groups. Chromatic aberration across the entire visible light spectrum is corrected by limiting the Abbe number of the materials of each optical element in the first, second, and third lens groups. Thus, this microscope objective achieves a large numerical aperture, a long working distance, full visible light chromatic aberration correction, and also possesses good field flatness, low distortion, and high resolution. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the optical system of the microscope objective described in the embodiments of this application;

[0021] Figure 2 This is a schematic diagram of the optical system of a microscope objective according to another embodiment of this application;

[0022] Figure 3 The optical system of the microscope objective described in the embodiments of this application Figure 1 Field curvature diagram of the structure;

[0023] Figure 4 The optical system of the microscope objective described in the embodiments of this application Figure 1 Distortion diagram of the structure;

[0024] Figure 5 The optical system of the microscope objective described in the embodiments of this application Figure 2 Field curvature diagram of the structure;

[0025] Figure 6 The optical system of the microscope objective described in the embodiments of this application Figure 2 Distortion diagram of the structure. Detailed Implementation

[0026] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] In the embodiments of this application, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0029] This application provides a microscope objective and its optical system, which solves the technical problems of existing microscopes, such as insufficient numerical aperture, insufficient resolution, insufficient working distance, and insufficient working wavelength.

[0030] Example 1:

[0031] Figure 1 This is a schematic diagram of the optical system of the microscope objective described in the embodiments of this application.

[0032] like Figure 1 As shown, this application provides an optical system for a microscope objective, including a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, and a third lens group G3 with positive or negative refractive power arranged sequentially from the object side to the image side.

[0033] It should be noted that the first lens group G1, the second lens group G2, and the third lens group G3 are arranged sequentially from the object side to the image side to form the optical system of the microscope objective.

[0034] In the embodiments of this application, the first lens group G1 includes at least one or more optical elements with positive refractive power, and the second lens group G2 includes at least two or more optical elements with positive refractive power. The Abbe number of the material of the optical elements is greater than a first threshold.

[0035] It should be noted that the first threshold can be 70. The optical element can be a lens. In this embodiment, the Abbe number of the optical element material is set by the first lens group G1 and the second lens group G2, enabling the optical system of the microscope objective to have chromatic aberration correction capability across the entire visible light spectrum. Since the Abbe number affects the chromatic aberration correction across the entire visible light spectrum of the microscope objective's optical system, by including at least one lens with positive refractive power in the first lens group G1, and the Abbe number V of the lens material being greater than 70; and by including at least two lenses with positive refractive power in the second lens group G2, and the Abbe number V of the lens material being greater than 70, the optical system of the microscope objective can operate across the entire visible light spectrum. In other embodiments, the first threshold can also be set as needed.

[0036] This application provides an optical system for a microscope objective, comprising a first lens group with positive refractive power, a second lens group with positive refractive power, and a third lens group with positive or negative refractive power, arranged sequentially from the object side to the image side. The first lens group includes at least one or more optical elements with positive refractive power, and the second lens group includes at least two or more optical elements with positive refractive power. The Abbe number of the material of the optical elements is greater than a first threshold. By setting the Abbe number of the optical element material in the first and second lens groups, the optical system of this microscope objective can operate across the entire wavelength range. The arrangement of the first, second, and third lens groups enables the optical system of this microscope objective to achieve high resolution, realize chromatic aberration correction across the entire visible light wavelength range, and maintain the characteristics of low field curvature and low distortion. This solves the technical problems of existing microscopes, such as insufficient numerical aperture, insufficient resolution, insufficient working distance, and too small working wavelength.

[0037] In one embodiment of this application, the ratio of the focal distance of the first lens group G1 to the focal distance of the optical system is greater than a second threshold and less than a third threshold; the ratio of the focal distance of the second lens group G2 to the focal distance of the optical system is greater than a fourth threshold and less than a fifth threshold; the ratio of the focal distance of the third lens group G3 to the focal distance of the optical system is greater than a sixth threshold and less than a seventh threshold; and the ratio of the length formed by the first lens group G1, the second lens group G2, and the third lens group G3 to the focal distance of the optical system is greater than an eighth threshold and less than a ninth threshold.

[0038] It should be noted that the second threshold can be 0.9, the third threshold can be 1.2, the fourth threshold can be 7.0, the fifth threshold can be 15.0, the sixth threshold can be -30, the seventh threshold can be 40, the eighth threshold can be 5.0, and the ninth threshold can be 5.8. In this embodiment, in order to enable the optical system of the microscope objective to have a large numerical aperture, a long working distance, and use a small number of lenses, the optical system of the microscope objective must meet the following first constraint condition, which is:

[0039] 0.9 <fG1 / f<1.2

[0040] 7.0 <fG2 / f<15.0

[0041] -30 <fG3 / f<40

[0042] 5.0 <L / f<5.8

[0043] In the formula, f is the focal distance of the optical system, fG1 is the focal distance of the first lens group, fG2 is the focal distance of the second lens group, fG3 is the focal distance of the third lens group, and L is the length formed by the first lens group G1, the second lens group G2, and the third lens group G3. L can also be understood as the total length of the optical system of the microscope objective. Because fG1 affects the numerical aperture of the optical system of the microscope objective, fG2 affects the chromatic aberration of the optical system of the microscope objective, and fG3 affects the field curvature of the optical system of the microscope objective, the optical system of the microscope objective, through the defined first constraint condition, possesses the characteristics of a large numerical aperture and a long working distance, and uses fewer lenses, thus reducing the cost of the optical system of the microscope objective.

[0044] Figure 2 This is a schematic diagram of the optical system of a microscope objective according to another embodiment of this application.

[0045] In one embodiment of this application, the first lens group G1 includes a first optical element L1 with negative refractive power, a second optical element L2 with positive refractive power, and a third optical element L3 with positive refractive power, arranged sequentially from the object side to the image side; and / or, the second lens group G2 includes a fourth optical element L4 with positive refractive power and a fifth optical element L5 with negative refractive power, arranged sequentially from the object side to the image side; and / or, the third lens group G3 includes a sixth optical element L6 with negative refractive power and a seventh optical element L7 with positive refractive power, arranged sequentially from the object side to the image side. Wherein, the ratio of the distance from the object side to the first lens group G1 to the focal distance of the optical system is less than a tenth threshold; the ratio of the distance from the first lens group G1 to the second lens group G2 to the focal distance of the optical system is less than an eleventh threshold; and the ratio of the distance from the second lens group G2 to the third lens group G3 to the focal distance of the optical system is less than a twelfth threshold.

[0046] It should be noted that the tenth threshold can be 0.12, the eleventh threshold can be 0.4, and the twelfth threshold can be 0.3. In this embodiment, as... Figure 1 As shown, the first optical element L1 is selected as a lens, the second optical element L2 is selected as a lens, the third optical element L3 is selected as a first cemented lens; the fourth optical element L4 is selected as a second cemented lens, the fifth optical element L5 is selected as a first cemented lens; the sixth optical element L6 is selected as a first cemented lens, and the seventh optical element L7 is selected as a lens. Figure 2 As shown, the first optical element L1 is selected as the first cemented lens, the second optical element L2 is selected as a lens, and the third optical element L3 is selected as a lens; the fourth optical element L4 is selected as the second cemented lens, and the fifth optical element L5 is selected as the first cemented lens; the sixth optical element L6 is selected as the first cemented lens, and the seventh optical element L7 is selected as a lens. To ensure that the optical system of this microscope objective has high resolution, achieves chromatic aberration correction across the entire visible light spectrum, and maintains low field curvature and low distortion, the optical system parameters of this microscope objective must satisfy the following second constraint condition:

[0047] d1 / f<0.12

[0048] d² / f < 0.4

[0049] d3 / f < 0.3

[0050] In the formula, d1 is the distance from the object side to the first lens group, d2 is the distance from the first lens group to the second lens group, d3 is the distance from the second lens group to the third lens group, and f is the focal distance of the optical system.

[0051] In the embodiments of this application, the first cemented lens is a cemented lens composed of two lenses; the second cemented lens is a cemented lens composed of two or more lenses.

[0052] Figure 3 The optical system of the microscope objective described in the embodiments of this application Figure 1 Field curvature diagram of the structure Figure 4 The optical system of the microscope objective described in the embodiments of this application Figure 1 Distortion diagram of the structure Figure 5 The optical system of the microscope objective described in the embodiments of this application Figure 2 Field curvature diagram of the structure Figure 6 The optical system of the microscope objective described in the embodiments of this application Figure 2 The distortion diagram of the structure. Among them, Figure 3 and Figure 5 The x-axis represents the offset from the object surface, in mm. Figure 3 and Figure 5 The ordinate is the normalized field of view, with a maximum value of 1. Figure 3 and Figure 5 The solid line represents the sagittal plane of the light ray. Figure 3 and Figure 5 The dashed line represents the meridional plane of the light. Figure 4 and Figure 6 The x-axis represents the distorted variable, in percentage. Figure 4 and Figure 6 The ordinate is the normalized field of view, with a maximum value of 1.

[0053] In this application embodiment, the optical system of the microscope objective is illustrated using the following two examples. Example 1: Figure 1 As shown, the optical system of this microscope objective includes an object plane, a first lens group G1, a second lens group G2, and a third lens group G3. The object-side numerical aperture NA of the optical system is set to 0.8, the object-side field of view to 1.25 mm, the focal distance f to 9 mm, the working distance to 0.81 mm, and the magnification to 20X. The parameters of the optical system of this microscope objective are shown in Table 1.

[0054] Table 1 shows the parameters of the optical system for the microscope objectives in Example 1.

[0055]

[0056] Based on the parameters in Table 1, we obtain fG1 / f=1.0, fG2 / f=8.3, fG3 / f=-23.6, L / f=5.3, d1 / f=0.09, d2 / f=0.31, d3 / f=0.17, the Abbe number of the material of the second optical element L2 is VL2=81.6, the focal length of the second optical element L2 is fL2=22.6mm, the Abbe number of the material of the third lens is VL=71.3, the focal length of the third lens is fL=13.4mm, the Abbe number of the material of the sixth lens is VL=71.3, the focal length of the sixth lens in the fourth optical element L4 is fL=15.2mm, the Abbe number of the material of the eighth lens in the fifth optical element L5 is VL=81.6, and the focal length of the eighth lens in the fifth optical element L5 is fL=16.3mm. As described above, in the optical system of the microscope objective of this embodiment, the focal length of the first lens group G1 is 9.2 mm, the focal length of the second lens group G2 is 74.5 mm, and the focal length of the third lens group G3 is -212 mm. Figure 1 It can be seen that, from the object side to the image side, the following are arranged: a first lens L1 with negative refractive power, a second lens L2 with positive refractive power, a third optical element L3 composed of a third lens with positive refractive power and a fourth lens with negative refractive power, a fourth optical element L4 composed of a fifth lens with negative refractive power and a sixth lens with positive refractive power, a fifth optical element L5 composed of a seventh lens with negative refractive power and an eighth lens with positive refractive power, a sixth optical element L6 composed of a ninth lens with positive refractive power and a tenth lens with negative refractive power, and an eleventh lens L7 with positive refractive power. The third optical element L3, formed by combining the third and fourth lenses, has a focal length of 32.3 mm. The fourth optical element L4, formed by combining the fifth and sixth lenses, has a focal length of 53.6 mm. The fifth optical element L5, formed by combining the seventh and eighth lenses, has a focal length of -178 mm. The sixth optical element L6, formed by combining the ninth and tenth lenses, has a focal length of -24.3 mm. Figure 3 The field curvature distribution shows that the field curvature of the optical system of this large numerical aperture, large field-of-view microscope objective is controlled within ±0.7 mm, indicating that the optical system of this microscope objective has excellent field flatness. From Figure 4 The distribution of distortion shows that the distortion of the optical system of this microscope objective is controlled within ±1%, indicating that the optical system of this microscope objective has small distortion.

[0057] In the embodiments of this application, Case 2: Figure 2As shown, the optical system of this microscope objective includes an object plane, a first lens group G1, a second lens group G2, and a third lens group G3. The object-side numerical aperture NA of the optical system is set to 0.8, the object-side field of view to 1.25 mm, the focal distance f to 9 mm, the working distance to 0.84 mm, and the magnification to 20X. The parameters of the optical system of this microscope objective are shown in Table 2.

[0058] Table 2 shows the parameters of the optical system for the microscope objectives in Example 2.

[0059]

[0060] Based on the parameters in Table 1, we obtain fG1 / f=1.1, fG2 / f=13.6, fG3 / f=-34.8, L / f=5.5, d1 / f=0.09, d2 / f=0.02, d3 / f=0.13, the Abbe number of the material of the third optical element L3 is VL3=81.6, the focal length of the third optical element L3 is fL3=28.3mm, the Abbe number of the material of the seventh lens in the fourth optical element L4 is VL=81.6, the focal length of the seventh lens in the fourth optical element L4 is fL=21.9mm, the Abbe number of the material of the ninth lens in the fifth optical element L5 is VL=81.6, the focal length of the ninth lens in the fifth optical element L5 is fL=21.9mm, and the focal length of the eighth lens in the fifth optical element L5 is fL=16.3mm. As described above, in the optical system of the microscope objective of this embodiment, the focal length of the first lens group G1 is 9.5 mm, the focal length of the second lens group G2 is 122 mm, and the focal length of the third lens group G3 is 313 mm. Figure 2 It can be seen that, from the object side to the image side, the following optical elements are configured: a first optical element L1 consisting of a first lens with negative refractive power and a second lens with positive refractive power; a second optical element L2 consisting of a positive refractive power; a third optical element L3 consisting of a positive refractive power; a fourth optical element L4 consisting of a fifth lens with positive refractive power, a sixth lens with negative refractive power, and a seventh lens with positive refractive power; a fifth optical element L5 consisting of an eighth lens with negative refractive power and a ninth lens with positive refractive power; a sixth optical element L6 consisting of a tenth lens with positive refractive power and an eleventh lens with negative refractive power; and a seventh optical element L7 consisting of positive refractive power. The first optical element L1, formed by combining the first and second lenses, has a focal length of -32.8 mm. The fourth optical element L4, formed by combining the fifth, sixth, and seventh lenses, has a focal length of 71.0 mm. The fifth optical element L5, formed by combining the eighth and ninth lenses, has a focal length of -149 mm. The sixth optical element L6, formed by combining the tenth and eleventh lenses, has a focal length of -41.4 mm. Figure 5The field curvature distribution shows that the field curvature of the optical system of this large numerical aperture, large field-of-view microscope objective is controlled within ±1.0 mm, indicating that the optical system of this microscope objective has excellent field flatness. From Figure 6 The distribution of distortion shows that the distortion of the optical system of this microscope objective is controlled within ±0.8%, indicating that the optical system of this microscope objective has small distortion.

[0061] In this embodiment, the optical system of the microscope objective uses fewer lenses by limiting the Abbe number of the lens material in combination with the first and second constraints. It also features a large numerical aperture, high resolution, long working distance, and chromatic aberration correction across the entire visible light spectrum, while maintaining low field curvature and low distortion.

[0062] Example 2:

[0063] This application provides a microscope objective, including the optical system of the microscope objective described above, wherein the distortion of the microscope objective is controlled within -1% to 1%.

[0064] It should be noted that the optical system of the microscope objective has been described in Embodiment 1, and will not be repeated in this embodiment. In this embodiment, the microscope objective is configured with a first lens group, a second lens group, and a third lens group. The first lens group has positive refractive power, the second lens group has positive refractive power, and the third lens group has either positive or negative refractive power. This ensures a long working distance of the microscope objective while maintaining a large numerical aperture. Furthermore, the arrangement of the optical elements in the first, second, and third lens groups results in a large aperture, high resolution, good imaging performance over a wide wavelength range, and well-corrected chromatic aberration.

[0065] In this embodiment, the microscope objective achieves a long working distance with a large numerical aperture by limiting the focal distance of the first, second, and third lens groups, while using fewer lenses and initially correcting spherical aberration, field curvature, and distortion. The microscope objective further corrects aberrations by limiting the spacing between the first, second, and third lens groups. The microscope objective corrects chromatic aberration across the entire visible light spectrum by limiting the Abbe number of the materials of each optical element in the first, second, and third lens groups. Thus, the microscope objective achieves a large numerical aperture, a long working distance, full-spectrum chromatic aberration correction, and also possesses good field flatness, low distortion, and high resolution.

[0066] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0067] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0068] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0069] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0070] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An optical system of a microscope objective, characterized in that The first lens group, the second lens group and the third lens group are arranged in the order of object side to image side, the first lens group has positive refractive power, the second lens group has positive refractive power, and the third lens group has positive or negative refractive power; The first lens group comprises at least one and more than one optical element with positive refractive power, the second lens group comprises at least two and more than two optical elements with positive refractive power, and the Abbe number of the material of the optical elements is greater than a first threshold value; The ratio of the distance from the object side to the first lens group to the focal length of the optical system is less than a tenth threshold value; The ratio of the distance from the first lens group to the second lens group to the focal length of the optical system is less than an eleventh threshold value, the ratio of the distance from the second lens group to the third lens group to the focal length of the optical system is less than a twelfth threshold value, the tenth threshold value is 0.12, the eleventh threshold value is 0.4, and the twelfth threshold value is 0.3; The third lens group comprises a sixth optical element with negative refractive power and a seventh optical element with positive refractive power arranged in the order of object side to image side, the sixth optical element is a first cemented lens, and the seventh optical element is a lens.

2. The optical system of a microscope objective according to claim 1, characterized in that The ratio of the focal length of the first lens group to the focal length of the optical system is greater than a second threshold value and less than a third threshold value, the ratio of the focal length of the second lens group to the focal length of the optical system is greater than a fourth threshold value and less than a fifth threshold value, the ratio of the focal length of the third lens group to the focal length of the optical system is greater than a sixth threshold value and less than a seventh threshold value, and the ratio of the length of the first lens group, the second lens group and the third lens group to the focal length of the optical system is greater than an eighth threshold value and less than a ninth threshold value.

3. The optical system of a microscope objective according to claim 2, characterized in that The second threshold value is 0.9, the third threshold value is 1.2, the fourth threshold value is 7.0, the fifth threshold value is 15.0, the sixth threshold value is -30, the seventh threshold value is 40, the eighth threshold value is 5.0, and the ninth threshold value is 5.

8.

4. The optical system of a microscope objective according to any one of claims 1 to 3, characterized in that The first threshold value is 70.

5. The optical system of a microscope objective according to any one of claims 1 to 3, characterized in that The first lens group comprises a first optical element with negative refractive power, a second optical element with positive refractive power and a third optical element with positive refractive power arranged in the order of object side to image side, and / or the second lens group comprises a fourth optical element with positive refractive power and a fifth optical element with negative refractive power arranged in the order of object side to image side.

6. The optical system of a microscope objective according to claim 5, characterized in that The first optical element is a lens or a first cemented lens, the second optical element is a lens, and the third optical element is a lens or a first cemented lens, and / or the fourth optical element is a second cemented lens, and the fifth optical element is a first cemented lens.

7. The optical system of a microscope objective according to claim 6, characterized in that The first cemented lens is a cemented lens composed of two lenses, and / or the second cemented lens is a cemented lens composed of two and more than two lenses.

8. A microscope objective, characterized in that An optical system comprising the microscope objective according to any one of claims 1-7, wherein the distortion of the microscope objective is controlled within -1% to 1%.

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