An optical microscope objective
By designing a lens group with negative and positive optical power, combined with ultra-low dispersion materials and cemented lenses, the trade-off between working distance and numerical aperture in optical microscope objectives has been resolved. This has resulted in optical microscope objectives with high magnification, long working distance, and large numerical aperture, reducing production costs and improving imaging quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- XIAMEN UNIV OF TECH
- Filing Date
- 2024-01-16
- Publication Date
- 2026-05-26
AI Technical Summary
In optical microscope objectives, how to balance working distance and numerical aperture to achieve high magnification, long working distance, large numerical aperture, and simple processing, while solving the problem of increased difficulty in correcting on-axis aberrations and magnification chromatic aberration.
The lens design employs a first group of negative optical power, a second group of positive optical power, and a third group of positive optical power. It combines ultra-low dispersion materials and cemented lens combinations to optimize focal length relationships and lens combinations, eliminate chromatic aberration and axial chromatic aberration, and improve numerical aperture.
This invention enables optical microscope objectives with ultra-long working distance and large numerical aperture, reducing production costs and improving imaging quality and resolution to meet high detection requirements.
Smart Images
Figure CN224287239U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lens technology, specifically to an optical microscope objective. Background Technology
[0002] With the development of the semiconductor industry, the requirements for inspecting the surface roughness of semiconductor wafers are becoming increasingly stringent. To reduce the limitations of using optical microscope objectives, these objectives must avoid contact with the sample and possess high resolution. This makes optical microscope objectives with long working distances and large numerical apertures the preferred choice for industrial inspection.
[0003] However, with long working distances, increasing the numerical aperture of optical microscope objectives makes it more difficult to correct on-axis aberrations and chromatic aberration, severely affecting imaging performance. Therefore, in conventional optical microscope objectives, to achieve higher detection resolution, the working distance must be sacrificed; while to improve the operability of actual detection, the numerical aperture needs to be reduced.
[0004] Finding a balance between working distance and numerical aperture to achieve optical microscope objectives with high magnification, long working distance, large numerical aperture, and simple fabrication has become an urgent problem to be solved. Utility Model Content
[0005] The technical problem to be solved by this utility model is to provide an optical microscope objective.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:
[0007] An optical microscope objective includes a first group (A) of negative optical power, a second group (B) of positive optical power, and a third group (C) of positive optical power arranged sequentially along the incident direction of light.
[0008] The focal lengths of each group satisfy the following relationship:
[0009] 5.1 < |fA / fS| < 6.3;
[0010] 2.2 < |fC / fS| < 3.4;
[0011] Where: fA is the focal length of the first group, fC is the focal length of the third group, and fS is the focal length of the objective lens;
[0012] The focal length fA of the first group is: -29mm < fA < -17mm;
[0013] The focal length fC of the third group is: 6mm < fC < 18mm.
[0014] As a further improvement, the first group (A) employs two sets of cemented doublet lenses and one set of lenses, which is beneficial for controlling field curvature and eliminating chromatic aberration; the second group (B) employs two sets of cemented doublet lenses and two sets of cemented triplet lenses, which is beneficial for eliminating axial chromatic aberration of the system; the third group (C) has at least three meniscus single lenses, which can be used to significantly increase the numerical aperture.
[0015] To improve resolution, at least two lenses in the first group (A) use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0016] To further improve resolution, at least six lenses in the second group (B) use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0017] As a preferred embodiment, the first group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the incident direction of light.
[0018] The first lens is a biconvex lens with positive optical power, and the second lens is a biconvex lens with negative optical power. The first lens and the second lens form a cemented doublet.
[0019] The third lens is a biconcave lens with negative optical power, and the fourth lens is a meniscus lens with negative optical power. The third lens and the fourth lens form a cemented doublet.
[0020] The fifth lens is a meniscus lens with positive optical power.
[0021] As a preferred embodiment, the second group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens arranged sequentially along the incident direction of light.
[0022] The sixth lens is a negative optical power biconcave lens, and the seventh lens is a positive optical power biconvex lens. The sixth lens and the seventh lens form a cemented doublet.
[0023] The eighth lens is a negative optical power biconcave lens, and the ninth lens is a positive optical power biconvex lens. The eighth lens and the ninth lens form a double cemented lens assembly.
[0024] The tenth lens is a biconvex lens with negative optical power, the eleventh lens is a biconcave lens with negative optical power, and the twelfth lens is a biconvex lens with positive optical power. The tenth lens, the eleventh lens, and the twelfth lens form a three-cemented lens group.
[0025] The thirteenth lens is a biconvex lens with negative optical power, the fourteenth lens is a biconcave lens with negative optical power, and the fifteenth lens is a biconvex lens with positive optical power. The thirteenth, fourteenth, and fifteenth lenses form a triplet.
[0026] As a preferred embodiment, the third group includes a sixteenth lens, a seventeenth lens, and an eighteenth lens arranged sequentially along the incident direction of the light;
[0027] The sixteenth lens is a biconcave lens with positive optical power, the seventeenth lens is a meniscus lens with positive optical power, and the eighteenth lens is a meniscus lens with positive optical power.
[0028] The beneficial effects of this utility model are as follows:
[0029] This invention provides an optical microscope objective that, compared to similar designs, boasts an ultra-long working distance (greater than 6.10 mm) and a large numerical aperture (greater than or equal to 0.75), while also being simple to manufacture, significantly reducing the actual production cost of the objective. The first group employs two sets of cemented doublet lenses and one set of single lenses, which helps control field curvature and eliminate chromatic aberration; the second group employs two sets of cemented doublet lenses and two sets of cemented triplets, which helps eliminate axial chromatic aberration in the system; the third group contains at least three meniscus single lenses, which can be used to significantly increase the numerical aperture. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the optical microscope objective structure according to Embodiment 1 of this utility model;
[0031] Figure 2 This is the MTF curve of the optical microscope objective of Embodiment 1 of this utility model;
[0032] Figure 3 This is the optical path difference diagram of the optical microscope objective of Embodiment 1 of this utility model;
[0033] Figure 4 This is a field curvature distortion diagram of the optical microscope objective of Embodiment 1 of this utility model;
[0034] Figure 5 This is a schematic diagram of the optical microscope objective structure according to Embodiment 2 of this utility model;
[0035] Figure 6 This is the MTF curve of the optical microscope objective of Embodiment 2 of this utility model;
[0036] Figure 7 This is the optical path difference diagram of the optical microscope objective of Embodiment 2 of this utility model;
[0037] Figure 8 This is a field curvature distortion diagram of the optical microscope objective of Embodiment 2 of this utility model;
[0038] Figure 9 This is a schematic diagram of the optical microscope objective lens structure according to Embodiment 3 of this utility model;
[0039] Figure 10 This is the MTF curve of the optical microscope objective of Embodiment 3 of this utility model;
[0040] Figure 11 This is the optical path difference diagram of the optical microscope objective of Embodiment 3 of this utility model;
[0041] Figure 12 This is a field curvature distortion diagram of the optical microscope objective of Embodiment 3 of this utility model;
[0042] Label Explanation:
[0043] A, First group; A1, First lens; A2, Second lens; A3, Third lens; A4, Fourth lens; A5, Fifth lens;
[0044] B, Second Group; B1, Sixth Lens; B2, Seventh Lens; B3, Eighth Lens; B4, Ninth Lens; B5, Tenth Lens; B6, Eleventh Lens; B7, Twelfth Lens; B8, Thirteenth Lens; B9, Fourteenth Lens; B10, Fifteenth Lens;
[0045] C, Group 3; C1, Lens 16; C2, Lens 17; C3, Lens 18. Detailed Implementation
[0046] To explain in detail the technical content, objectives, and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.
[0047] Example 1:
[0048] This embodiment relates to an optical microscope objective, such as... Figure 1 As shown, it includes a first group A of negative optical power, a second group B of positive optical power, and a third group C of positive optical power arranged sequentially from the object side to the image side along the optical axis;
[0049] The focal lengths of each group satisfy the following relationship:
[0050] 5.1 < |fA / fS| < 6.3;
[0051] 2.2 < |fC / fS| < 3.4;
[0052] Where: fA is the focal length of the first group, fC is the focal length of the third group, and fS is the focal length of the objective lens;
[0053] The focal length fA of the first group is: -27mm < fA < -14mm;
[0054] The focal length fC of the third group is: 6mm < fC < 18mm.
[0055] As a further improvement, the first group A uses two sets of cemented doublet lenses and one set of lenses, which is beneficial for controlling field curvature and eliminating chromatic aberration; the second group B uses two sets of cemented doublet lenses and two sets of cemented triplet lenses, which is beneficial for eliminating axial chromatic aberration of the system; the third group C has at least three meniscus single lenses, which can be used to significantly increase the numerical aperture.
[0056] To improve resolution, at least two lenses in the first group A use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0057] To further improve resolution, at least six lenses in the second group B use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0058] As a preferred embodiment, the first group includes a first lens A1, a second lens A2, a third lens A3, a fourth lens A4, and a fifth lens A5 arranged sequentially along the incident direction of light.
[0059] The first lens A1 is a biconvex lens with positive optical power, and the second lens A2 is a biconvex lens with negative optical power. The first lens A1 and the second lens A2 form a cemented doublet.
[0060] The third lens A3 is a biconcave lens with negative optical power, and the fourth lens A4 is a meniscus lens with negative optical power. The third lens A3 and the fourth lens A4 form a cemented doublet.
[0061] The fifth lens A5 is a meniscus lens with positive optical power.
[0062] As a preferred embodiment, the second group includes a sixth lens B1, a seventh lens B2, an eighth lens B3, a ninth lens B4, a tenth lens B5, an eleventh lens B6, a twelfth lens B7, a thirteenth lens B8, a fourteenth lens B9, and a fifteenth lens B10 arranged sequentially along the incident direction of light.
[0063] The sixth lens B1 is a negative optical power biconcave lens, and the seventh lens B2 is a positive optical power biconvex lens. The sixth lens B1 and the seventh lens B2 form a double cemented lens.
[0064] The eighth lens B3 is a biconcave lens with negative optical power, and the ninth lens B4 is a biconvex lens with positive optical power. The eighth lens B3 and the ninth lens B4 form a double cemented lens.
[0065] The tenth lens B5 is a biconvex lens with negative optical power, the eleventh lens B6 is a biconcave lens with negative optical power, and the twelfth lens B7 is a biconvex lens with positive optical power. The tenth lens B5, the eleventh lens B6, and the twelfth lens B7 form a triplet.
[0066] The thirteenth lens B8 is a biconvex lens with negative optical power, the fourteenth lens B9 is a biconcave lens with negative optical power, and the fifteenth lens B10 is a biconvex lens with positive optical power. The thirteenth lens B8, the fourteenth lens B9, and the fifteenth lens B10 form a triplet.
[0067] As a preferred embodiment, the third group includes a sixteenth lens C1, a seventeenth lens C2, and an eighteenth lens C3 arranged sequentially along the incident direction of light.
[0068] The sixteenth lens C1 is a biconcave lens with positive optical power, the seventeenth lens C2 is a meniscus lens with positive optical power, and the eighteenth lens C3 is a meniscus lens with positive optical power.
[0069] Specifically, the lens has a focal length fS of 3.98mm, a focal length NA of 0.75, an image plane diameter of 0.482mm, an entrance pupil diameter of 5.97mm, and a total lens length of 97.00mm. The radius of curvature, center thickness, refractive index nd, and Abbe number vd of each lens are shown in Table 1 below (the surface numbers in the table are set sequentially along the direction of light incidence).
[0070]
[0071]
[0072] Table 1
[0073] Based on the data in Table 1 and the relevant formulas above, we can obtain:
[0074] fS=3.98; fA=-22.907; fC=13.178; |fA / fS|=5.756; |fC / fS|=3.311.
[0075] The lens provided in Embodiment 1 will be further described below through a detailed optical system analysis.
[0076] Figure 2 The MTF curve of the optical microscope objective in this embodiment represents the entire field of view. The vertical axis represents the normalized OTF modulus, and the horizontal axis represents the spatial frequency, with units of lp / mm. The figure shows that both the on-axis and off-axis full-field transfer function curves are close to the diffraction limit, indicating that the optical system has good imaging quality and clear tonal range across the entire field of view.
[0077] Figure 3The graph shows the optical path difference of the optical microscope objective. It can be seen that the optical path difference of the system is within 0.5 wavelength in the visible light band, and the performance of each field of view almost reaches the diffraction limit, which shows good imaging performance.
[0078] Figure 4 These are field curvature and distortion diagrams for optical microscope objectives. The left image shows the field curvature, where the vertical axis represents the field of view and the horizontal axis represents the field curvature, both in μm. The axial difference between the optimal focusing point at the edge of the field of view and the optimal focusing point at the center of the field of view is less than 2λ / NA², theoretically satisfying the requirement for sharpness across the entire field of view and meeting the requirements for a field-plan objective. The vertical axis represents the normalized field of view; the horizontal axis represents the field curvature, with a maximum value of 2 μm and a minimum value of -2 μm. The right image shows the distortion, where the vertical axis represents the field of view and the horizontal axis represents the distortion (percentage). As shown in the image, the distortion across the entire field of view is less than 0.5%.
[0079] Example 2:
[0080] Another embodiment has the following specific structure: This embodiment relates to an optical microscope objective, such as... Figure 4 As shown, it includes a first group A of negative optical power, a second group B of positive optical power, and a third group C of positive optical power arranged sequentially from the object side to the image side along the optical axis;
[0081] The focal lengths of each group satisfy the following relationship:
[0082] 5.1 < |fA / fS| < 6.3;
[0083] 2.2 < |fC / fS| < 3.4;
[0084] Where: fA is the focal length of the first group, fB is the focal length of the second group, fC is the focal length of the third group, and fS is the focal length of the objective lens;
[0085] The focal length fA of the first group is: -29mm < fA < -17mm;
[0086] The focal length fC of the third group is: 7mm < fC < 17mm.
[0087] As a further improvement, the first group A uses two sets of cemented doublet lenses and one set of lenses, which is beneficial for controlling field curvature and eliminating chromatic aberration; the second group B uses two sets of cemented doublet lenses and two sets of cemented triplet lenses, which is beneficial for eliminating axial chromatic aberration of the system; the third group C has at least three meniscus single lenses, which can be used to significantly increase the numerical aperture.
[0088] To improve resolution, at least two lenses in the first group A use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0089] To further improve resolution, at least six lenses in the second group B use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0090] As a preferred embodiment, the first group includes a first lens A1, a second lens A2, a third lens A3, a fourth lens A4, and a fifth lens A5 arranged sequentially along the incident direction of light.
[0091] The first lens A1 is a biconvex lens with positive optical power, and the second lens A2 is a biconvex lens with negative optical power. The first lens A1 and the second lens A2 form a cemented doublet.
[0092] The third lens A3 is a biconcave lens with negative optical power, and the fourth lens A4 is a meniscus lens with negative optical power. The third lens A3 and the fourth lens A4 form a cemented doublet.
[0093] The fifth lens A5 is a meniscus lens with positive optical power.
[0094] As a preferred embodiment, the second group includes a sixth lens B1, a seventh lens B2, an eighth lens B3, a ninth lens B4, a tenth lens B5, an eleventh lens B6, a twelfth lens B7, a thirteenth lens B8, a fourteenth lens B9, and a fifteenth lens B10 arranged sequentially along the incident direction of light.
[0095] The sixth lens B1 is a negative optical power biconcave lens, and the seventh lens B2 is a positive optical power biconvex lens. The sixth lens B1 and the seventh lens B2 form a double cemented lens.
[0096] The eighth lens B3 is a biconcave lens with negative optical power, and the ninth lens B4 is a biconvex lens with positive optical power. The eighth lens B3 and the ninth lens B4 form a double cemented lens.
[0097] The tenth lens B5 is a biconvex lens with negative optical power, the eleventh lens B6 is a biconcave lens with negative optical power, and the twelfth lens B7 is a biconvex lens with positive optical power. The tenth lens B5, the eleventh lens B6, and the twelfth lens B7 form a triplet.
[0098] The thirteenth lens B8 is a biconvex lens with negative optical power, the fourteenth lens B9 is a biconcave lens with negative optical power, and the fifteenth lens B10 is a biconvex lens with positive optical power. The thirteenth lens B8, the fourteenth lens B9, and the fifteenth lens B10 form a triplet.
[0099] As a preferred embodiment, the third group includes a sixteenth lens C1, a seventeenth lens C2, and an eighteenth lens C3 arranged sequentially along the incident direction of light.
[0100] The sixteenth lens C1 is a biconcave lens with positive optical power, the seventeenth lens C2 is a meniscus lens with positive optical power, and the eighteenth lens C3 is a meniscus lens with positive optical power.
[0101] Specifically, the lens has a focal length fS of 4.01 mm, a focal length NA of 0.75, an image plane diameter of 0.482 mm, an entrance pupil diameter of 6.00 mm, and a total lens length of 94.91 mm. The data for the radius of curvature, center thickness, refractive index nd, and Abbe number vd of each lens are shown in Table 2 below (the surface numbers in the table are set sequentially along the direction of light incidence).
[0102]
[0103]
[0104] Table 2
[0105] Based on the data in Table 2 and the relevant formulas above, we can obtain:
[0106] fS=4.01; fA=-23.497; fC=13.148; |fA / fS|=5.874; |fC / fS|=3.287.
[0107] The lens provided in Embodiment 2 will be further described below through a detailed optical system analysis.
[0108] Figure 6 The MTF curve of the optical microscope objective in this embodiment represents the entire field of view. The vertical axis represents the normalized OTF modulus, and the horizontal axis represents the spatial frequency, with units of lp / mm. The figure shows that both the on-axis and off-axis full-field transfer function curves are close to the diffraction limit, indicating that the optical system has good imaging quality and clear tonal range across the entire field of view.
[0109] Figure 7 The graph shows the optical path difference of the optical microscope objective. It can be seen that the optical path difference of the system is within 0.5 wavelength in the visible light band, and the performance of each field of view almost reaches the diffraction limit, which shows good imaging performance.
[0110] Figure 8 These are field curvature and distortion diagrams for optical microscope objectives. The left image shows the field curvature, where the vertical axis represents the field of view and the horizontal axis represents the field curvature, both in μm. The axial difference between the optimal focusing point at the edge of the field of view and the optimal focusing point at the center of the field of view is less than 2λ / NA², theoretically satisfying the requirement for sharpness across the entire field of view and meeting the requirements for a field-plan objective. The vertical axis represents the normalized field of view; the horizontal axis represents the field curvature, with a maximum value of 2 μm and a minimum value of -2 μm. The right image shows the distortion, where the vertical axis represents the field of view and the horizontal axis represents the distortion (percentage). As shown in the image, the distortion across the entire field of view is less than 0.5%.
[0111] Example 3:
[0112] Another embodiment has the following specific structure: This embodiment relates to an optical microscope objective, such as... Figure 7 As shown, it includes a first group A of negative optical power, a second group B of positive optical power, and a third group C of positive optical power arranged sequentially from the object side to the image side along the optical axis;
[0113] The focal lengths of each group satisfy the following relationship:
[0114] 4.8 < |fA / fS| < 7.0;
[0115] 2.0 < |fC / fS| < 4.3;
[0116] Where: fA is the focal length of the first group, fC is the focal length of the third group, and fS is the focal length of the objective lens;
[0117] The focal length fA of the first group is: -27mm < fA < -15mm;
[0118] The focal length fC of the third group is: 9mm < fC < 16mm.
[0119] As a further improvement, the first group A uses two sets of cemented doublet lenses and one set of lenses, which is beneficial for controlling field curvature and eliminating chromatic aberration; the second group B uses two sets of cemented doublet lenses and two sets of cemented triplet lenses, which is beneficial for eliminating axial chromatic aberration of the system; the third group C has at least three meniscus single lenses, which can be used to significantly increase the numerical aperture.
[0120] To improve resolution, at least two lenses in the first group A use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0121] To further improve resolution, at least six lenses in the second group B use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
[0122] As a preferred embodiment, the first group includes a first lens A1, a second lens A2, a third lens A3, a fourth lens A4, and a fifth lens A5 arranged sequentially along the incident direction of light.
[0123] The first lens A1 is a biconvex lens with positive optical power, and the second lens A2 is a biconvex lens with negative optical power. The first lens A1 and the second lens A2 form a cemented doublet.
[0124] The third lens A3 is a biconcave lens with negative optical power, and the fourth lens A4 is a meniscus lens with negative optical power. The third lens A3 and the fourth lens A4 form a cemented doublet.
[0125] The fifth lens A5 is a meniscus lens with positive optical power.
[0126] As a preferred embodiment, the second group includes a sixth lens B1, a seventh lens B2, an eighth lens B3, a ninth lens B4, a tenth lens B5, an eleventh lens B6, a twelfth lens B7, a thirteenth lens B8, a fourteenth lens B9, and a fifteenth lens B10 arranged sequentially along the incident direction of light.
[0127] The sixth lens B1 is a negative optical power biconcave lens, and the seventh lens B2 is a positive optical power biconvex lens. The sixth lens B1 and the seventh lens B2 form a double cemented lens.
[0128] The eighth lens B3 is a biconcave lens with negative optical power, and the ninth lens B4 is a biconvex lens with positive optical power. The eighth lens B3 and the ninth lens B4 form a double cemented lens.
[0129] The tenth lens B5 is a biconvex lens with negative optical power, the eleventh lens B6 is a biconcave lens with negative optical power, and the twelfth lens B7 is a biconvex lens with positive optical power. The tenth lens B5, the eleventh lens B6, and the twelfth lens B7 form a triplet.
[0130] The thirteenth lens B8 is a biconvex lens with negative optical power, the fourteenth lens B9 is a biconcave lens with negative optical power, and the fifteenth lens B10 is a biconvex lens with positive optical power. The thirteenth lens B8, the fourteenth lens B9, and the fifteenth lens B10 form a triplet.
[0131] As a preferred embodiment, the third group includes a sixteenth lens C1, a seventeenth lens C2, and an eighteenth lens C3 arranged sequentially along the incident direction of light.
[0132] The sixteenth lens C1 is a biconcave lens with positive optical power, the seventeenth lens C2 is a meniscus lens with positive optical power, and the eighteenth lens C3 is a meniscus lens with positive optical power.
[0133] Specifically, the lens has a focal length fS of 4.026mm, a focal length NA of 0.769, an image plane diameter of 0.482mm, an entrance pupil diameter of 6.200mm, and a total lens length of 95.012mm. The radius of curvature, center thickness, refractive index nd, and Abbe number vd of each lens are shown in Table 3 below (the surface numbers in the table are set sequentially along the direction of light incidence).
[0134]
[0135]
[0136] Table 3
[0137] Based on the data in Table 3 above and the relevant formulas, we can obtain:
[0138] fS = 4.026; fA = -23.582; fC = 13.166; |fA / fS| = 5.896; |fC / fS| = 3.270. The lens provided in Embodiment 3 will be further described below through a detailed optical system analysis.
[0139] Figure 10 The MTF curve of the optical microscope objective in this embodiment represents the entire field of view. The vertical axis represents the normalized OTF modulus, and the horizontal axis represents the spatial frequency, with units of lp / mm. The figure shows that both the on-axis and off-axis full-field transfer function curves are close to the diffraction limit, indicating that the optical system has good imaging quality and clear tonal range across the entire field of view.
[0140] Figure 11 The graph shows the optical path difference of the optical microscope objective. It can be seen that the optical path difference of the system is within 0.5 wavelength in the visible light band, and the performance of each field of view almost reaches the diffraction limit, which shows good imaging performance.
[0141] Figure 12 These are field curvature and distortion diagrams for optical microscope objectives. The left image shows the field curvature, where the vertical axis represents the field of view and the horizontal axis represents the field curvature, both in μm. The axial difference between the optimal focusing point at the edge of the field of view and the optimal focusing point at the center of the field of view is less than 2λ / NA², theoretically satisfying the requirement for sharpness across the entire field of view and meeting the requirements for a field-plan objective. The vertical axis represents the normalized field of view; the horizontal axis represents the field curvature, with a maximum value of 2 μm and a minimum value of -2 μm. The right image shows the distortion, where the vertical axis represents the field of view and the horizontal axis represents the distortion (percentage). As shown in the image, the distortion across the entire field of view is less than 0.5%.
[0142] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent modifications made based on the content of this utility model specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of this utility model.
Claims
1. An optical microscope, characterized in that: It includes a first group of negative optical powers, a second group of positive optical powers, and a third group of positive optical powers arranged sequentially along the optical axis from the object side to the image side; The focal lengths of each group satisfy the following relationship: 5.1 < |fA / fS| < 6.3; 2.2 < |fC / fS| < 3.4; Where: fA is the focal length of the first group, fC is the focal length of the third group, and fS is the focal length of the objective lens; The focal length fA of the first group is: -29mm < fA < -17mm; The focal length fC of the third group is: 6mm < fC < 18mm.
2. An optical microscope objective according to claim 1, characterized in that: The first group uses two sets of cemented doublet lenses and one set of lenses; the second group uses two sets of cemented doublet lenses and two sets of cemented triplet lenses; the third group has at least three meniscus single lenses.
3. An optical microscope objective according to claim 1, characterized in that: At least two lenses in the first group use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
4. The optical microscope objective according to claim 1, characterized in that: At least six lenses in the second group use ultra-low dispersion materials with an Abbe number ranging from 90 to 100.
5. An optical microscope objective according to claim 1, characterized in that: The first group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the incident direction of light; the first lens is a biconvex lens with positive optical power, the second lens is a biconvex lens with negative optical power, the first lens and the second lens form a cemented doublet, the third lens is a biconcave lens with negative optical power, the fourth lens is a meniscus lens with negative optical power, the third lens and the fourth lens form a cemented doublet, and the fifth lens is a meniscus lens with positive optical power.
6. An optical microscope objective according to claim 5, characterized in that: The second group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens arranged sequentially along the incident direction of light. The sixth lens is a biconcave lens with negative optical power, the seventh lens is a biconvex lens with positive optical power, and the sixth and seventh lenses form a cemented doublet. The eighth lens is a biconcave lens with negative optical power, the ninth lens is a biconvex lens with positive optical power, and the eighth and ninth lenses form a cemented doublet. The tenth lens is a biconvex lens with negative optical power, the eleventh lens is a biconcave lens with negative optical power, the twelfth lens is a biconvex lens with positive optical power, and the tenth, eleventh, and twelfth lenses form a cemented triplet. The thirteenth lens is a biconvex lens with negative optical power, the fourteenth lens is a biconcave lens with negative optical power, the fifteenth lens is a biconvex lens with positive optical power, and the thirteenth, fourteenth, and fifteenth lenses form a cemented triplet.
7. An optical microscope objective according to claim 6, characterized in that: The third group includes a sixteenth lens, a seventeenth lens, and an eighteenth lens arranged sequentially along the incident direction of light; the sixteenth lens is a biconcave lens with positive optical power, the seventeenth lens is a meniscus lens with positive optical power, and the eighteenth lens is a meniscus lens with positive optical power.