Large numerical aperture long working distance apochromatic microscope objective

Abstract

The application discloses a large numerical aperture long working distance apochromatic microscope objective, which comprises, in sequence from an image plane to an object plane along an optical path, a first lens group for converging a light beam and correcting high-order aberrations, a second lens group, a third lens group and a fourth lens group for correcting spherical aberration and field curvature aberration, wherein the second lens group and the third lens group are both three cemented lens groups, the second lens group adopts a negative-positive-negative refractive power combination, and the third lens group adopts a positive-negative-positive refractive power combination. The application forms a cooperative aberration correction structure of correction first and compensation later through the second lens group and the third lens group, can effectively inhibit axial drift of a near-infrared machining focal point relative to a visible light observation focal point while realizing large numerical aperture and high-resolution imaging, can keep the observation positioning focal point and the laser hidden cutting machining focal point matched, and can improve the precision, efficiency and yield of wafer hidden cutting machining.

Description

Technical Field

[0001] This invention relates to the field of semiconductor wafer processing equipment technology, specifically to a large numerical aperture, long working distance apochromatic microscope objective. Background Technology

[0002] In semiconductor chip manufacturing, wafers typically undergo a dicing process to separate the chips. Traditional contact cutting methods such as diamond wheel cutting and abrasive wheel cutting can easily introduce mechanical damage to the wafer surface or edges, leading to problems such as edge chipping, cracks, fragmentation, and decreased chip performance. Silicon-based materials have high transmittance to near-infrared lasers; therefore, short-pulse near-infrared lasers can be used to focus energy inside the silicon substrate, forming a modified layer or perforations within the wafer. Then, through processes such as film expansion, cracks are induced to propagate along a predetermined path, achieving stealth dicing.

[0003] Existing laser lithography equipment typically needs to operate in two modes: visible light imaging observation and near-infrared laser processing. If the visible and near-infrared bands cannot be well confocalized, the equipment needs to refocus during the switching between observation, positioning, and processing, affecting processing efficiency and cutting accuracy. Meanwhile, to obtain higher focusing energy density and higher resolution, the objective lens needs to have a larger numerical aperture; however, with a larger numerical aperture, aberration correction, apochromatic aberration, working distance, and assembly tolerance control all become significantly more difficult. Summary of the Invention

[0004] Technical objective: To address the shortcomings of existing laser holographic cutting equipment, this invention discloses a large numerical aperture, long working distance apochromatic microscope objective capable of achieving high-resolution imaging and high-precision laser holographic cutting.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution: A large numerical aperture, long working distance apochromatic microscope objective includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the image plane to the object plane along the optical path for converging the beam and correcting higher-order aberrations. The second and third lens groups are both cemented triplet lens groups. The second lens group adopts a negative-positive-negative optical power combination and includes an eighth, ninth, and tenth lens arranged sequentially along the optical path. The third lens group adopts a positive-negative-positive optical power combination and includes an eleventh, twelfth, and thirteenth lens arranged sequentially along the optical path.

[0006] Preferably, the eighth lens of the present invention is a negative power plano-concave lens, the ninth lens is a positive power biconvex lens, the tenth lens is a negative power meniscus lens, the eleventh lens is a positive power biconvex lens, the twelfth lens is a negative power biconcave lens, and the thirteenth lens is a positive power biconvex lens.

[0007] Preferably, the focal length of the eighth lens of the present invention satisfies -19≤f8≤-18; the focal length of the ninth lens satisfies 18≤f9≤19; the focal length of the tenth lens satisfies -32≤f10≤-31; the focal length of the eleventh lens satisfies 33≤f11≤34; and the focal length of the twelfth lens satisfies -22≤f12≤-21.

[0008] Preferably, the refractive index and Abbe number of the eighth lens of the present invention are Nd8 and Vd8, respectively, where Nd8 = 1.79 and 25 ≤ Vd8 ≤ 30; The refractive index and Abbe number of the ninth lens are Nd9 and Vd9, respectively, Nd9=1.43, 95≤Vd9≤100; The refractive index and Abbe number of the tenth lens are Nd10 and Vd10, respectively, where Nd10 = 1.80 and 35 ≤ Vd10 ≤ 40; The refractive index and Abbe number of the eleventh lens are Nd11 and Vd11, respectively, where Nd11 = 1.43 and 95 ≤ Vd11 ≤ 100. The refractive index and Abbe number of the twelfth lens are Nd12 and Vd12, respectively, Nd12=1.61, 40≤Vd12≤45; The refractive index and Abbe number of the thirteenth lens are Nd13 and Vd13, respectively, where Nd13 = 1.43 and 95 ≤ Vd13 ≤ 100.

[0009] Preferably, the first lens group of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the optical path direction. The first lens is a negative power biconcave lens, the second lens is a positive power meniscus lens, the third lens is a positive power biconvex lens, the fourth lens is a negative power biconcave lens, the fifth lens is a negative power biconcave lens, the sixth lens is a positive power biconvex lens, and the seventh lens is a positive power biconvex lens.

[0010] Preferably, the focal length of the first lens of the present invention satisfies -12≤f1≤-11; the focal length of the second lens satisfies 16≤f2≤17; the focal length of the third lens satisfies 14≤f3≤15; the focal length of the fourth lens satisfies -10≤f4≤-9; the focal length of the fifth lens satisfies -7≤f5≤-6; the focal length of the sixth lens satisfies 11≤f6≤12; and the focal length of the seventh lens satisfies 26≤f7≤27.

[0011] Preferably, the refractive index and Abbe number of the first lens of the present invention are Nd1 and Vd1, respectively, where Nd1 = 1.59 and 65 ≤ Vd1 ≤ 70; The refractive index and Abbe number of the second lens are Nd2 and Vd2, respectively, Nd2=1.73, 50≤Vd2≤55; The refractive index and Abbe number of the third lens are Nd3 and Vd3, respectively, Nd3=1.81, 25≤Vd3≤30; The refractive index and Abbe number of the fourth lens are Nd4 and Vd4, respectively, Nd4=1.59, 65≤Vd4≤70; The refractive index and Abbe number of the fifth lens are Nd5 and Vd5, respectively, Nd5=1.95, 30≤Vd5≤35; The refractive index and Abbe number of the sixth lens are Nd6 and Vd6, respectively, where Nd6 = 1.73 and 25 ≤ Vd6 ≤ 30. The refractive index and Abbe number of the seventh lens are Nd7 and Vd7, respectively, where Nd7 = 1.46 and 90 ≤ Vd7 ≤ 95.

[0012] Preferably, the fourth lens group of the present invention includes a fourteenth lens, a fifteenth lens, and a sixteenth lens arranged sequentially along the optical path direction. The fourteenth lens is a positive optical power biconvex lens, the fifteenth lens is a positive optical power meniscus lens, and the sixteenth lens is a positive optical power meniscus lens.

[0013] Preferably, the focal length of the fourteenth lens of the present invention satisfies 74≤f14≤75; the focal length of the fifteenth lens satisfies 64≤f15≤65; and the focal length of the sixteenth lens satisfies 35≤f16≤36.

[0014] Preferably, the refractive index and Abbe number of the fourteenth lens of the present invention are Nd14 and Vd14, respectively, where Nd14 = 1.63 and 55 ≤ Vd14 ≤ 60; The refractive index and Abbe number of the fifteenth lens are Nd15 and Vd15, respectively, Nd15=1.63, 55≤Vd15≤60; The refractive index and Abbe number of the sixteenth lens are Nd16 and Vd16, respectively, where Nd16 = 1.81 and 30 ≤ Vd16 ≤ 35.

[0015] Beneficial effects: The large numerical aperture, long working distance apochromatic microscope objective disclosed in this invention has the following beneficial effects: 1. The objective lens of this invention adopts a confocal design for the visible light band and the near-infrared band, which can realize the switching between imaging observation and laser covert cutting without refocusing, thereby improving the positioning and processing efficiency of laser covert cutting equipment.

[0016] 2. This invention achieves a large numerical aperture design by initially focusing the light beam and correcting advanced aberrations through the first lens group, thereby improving the resolution of the objective lens and facilitating the acquisition of higher focusing energy density and clearer processing and observation images.

[0017] 3. The second and third lens groups of the present invention adopt a three-cemented lens group to form a pre-correction and re-compensation synergistic correction structure for imaging. This can suppress the axial drift of the near-infrared processing focus relative to the visible light observation focus under the condition of a large aperture and high convergence beam, so that the observation positioning focus and the laser hidden cutting processing focus are matched, thereby improving the stability of the internal modification layer or the position of the perforation in the silicon substrate and the consistency of the hidden cutting processing.

[0018] 4. The ninth and eleventh lenses of the present invention are preferably made of calcium fluoride material, which can be used in combination with different dispersive glasses, reducing the influence of the second-order spectrum and achieving apochromatic aberration, thus ensuring imaging quality. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 This is a schematic diagram of the structure of the laser concealed lens of the present invention.

[0021] Among them, 1-first lens, 2-second lens, 3-third lens, 4-fourth lens, 5-fifth lens, 6-sixth lens, 7-seventh lens, 8-eighth lens, 9-ninth lens, 10-tenth lens, 11-eleventh lens, 12-twelfth lens, 13-thirteenth lens, 14-fourteenth lens, 15-fifteenth lens, 16-sixteenth lens, 17-seventeenth lens, 18-first lens group, 19-second lens group, 20-third lens group, 21-fourth lens group. Detailed Implementation

[0022] Reference will now be made in detail to embodiments of the present disclosure, one or more of which are set forth herein. Each embodiment and example is provided by way of explanation of the apparatus, composition, and materials of the present disclosure, and not by way of limitation. Rather, the following description provides convenient illustrations for implementing exemplary embodiments of the present disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0023] like Figure 1As shown, this invention discloses a large numerical aperture, long working distance apochromatic microscope objective, comprising a first lens group 18, a second lens group 19, a third lens group 20, and a fourth lens group 21 arranged sequentially from the image plane to the object plane along the optical path for converging the beam and correcting higher-order aberrations; the second lens group 19 and the third lens group 20 are both cemented triplet lens groups; the second lens group 19 adopts a negative-positive-negative optical power combination, including an eighth lens 8, a ninth lens 9, and a tenth lens 10 arranged sequentially along the optical path; the third lens group 20 adopts a positive-negative-positive optical power combination, including an eleventh lens 11, a twelfth lens 12, and a thirteenth lens 13 arranged sequentially along the optical path.

[0024] This invention provides a large numerical aperture input through a first lens group 18 to converge the light beam and correct advanced aberrations. In an embodiment of this invention, the first lens group 18 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a seventh lens 7 arranged sequentially along the optical path. The first lens 1 is a negative power biconcave lens, the second lens 2 is a positive power meniscus lens, the third lens 3 is a positive power biconvex lens, the fourth lens 4 is a negative power biconcave lens, the fifth lens 5 is a negative power biconcave lens, the sixth lens 6 is a positive power biconvex lens, and the seventh lens 7 is a positive power biconvex lens.

[0025] For semiconductor wafer fabrication scenarios, the numerical aperture NA of this invention is preferably 0.67, and the resolution is preferably 0.41 μm. The corresponding focal lengths of the first lens 1 satisfy -12≤f1≤-11; the focal lengths of the second lens 2 satisfy 16≤f2≤17; the focal lengths of the third lens 3 satisfy 14≤f3≤15; the focal lengths of the fourth lens 4 satisfy -10≤f4≤-9; the focal lengths of the fifth lens 5 satisfy -7≤f5≤-6; the focal lengths of the sixth lens 6 satisfy 11≤f6≤12; and the focal lengths of the seventh lens 7 satisfy 26≤f7≤27. The refractive index and Abbe number of the first lens 1 are Nd1 and Vd1, respectively, with Nd1 = 1.59 and 65 ≤ Vd1 ≤ 70; the refractive index and Abbe number of the second lens 2 are Nd2 and Vd2, respectively, with Nd2 = 1.73 and 50 ≤ Vd2 ≤ 55; the refractive index and Abbe number of the third lens 3 are Nd3 and Vd3, respectively, with Nd3 = 1.81 and 25 ≤ Vd3 ≤ 30; the refractive index and Abbe number of the fourth lens 4 are Nd4 and Vd2, respectively. The refractive index and Abbe number of the fifth lens 5 are Nd5 and Vd5, respectively, with Nd5=1.95 and 30≤Vd5≤35. The refractive index and Abbe number of the sixth lens 6 are Nd6 and Vd6, respectively, with Nd6=1.73 and 25≤Vd6≤30. The refractive index and Abbe number of the seventh lens 7 are Nd7 and Vd7, respectively, with Nd7=1.46 and 90≤Vd7≤95.

[0026] To ensure image quality even with large numerical apertures, the eighth lens 8 of this invention is a negative power plano-concave lens, the ninth lens 9 is a positive power biconvex lens, the tenth lens 10 is a negative power meniscus lens, the eleventh lens 11 is a positive power biconvex lens, the twelfth lens 12 is a negative power biconcave lens, and the thirteenth lens 13 is a positive power biconvex lens. The focal length of the eighth lens 8 satisfies -19 ≤ f8 ≤ -18; the focal length of the ninth lens 9 satisfies 18 ≤ f9 ≤ 19; the focal length of the tenth lens 10 satisfies -32 ≤ f10 ≤ -31; the focal length of the eleventh lens 11 satisfies 33 ≤ f11 ≤ 34; and the focal length of the twelfth lens 12 satisfies -22 ≤ f12 ≤ -21. The refractive index and Abbe number of the eighth lens 8 are Nd8 and Vd8, respectively, with Nd8 = 1.79 and 25 ≤ Vd8 ≤ 30; the refractive index and Abbe number of the ninth lens 9 are Nd9 and Vd9, respectively, with Nd9 = 1.43 and 95 ≤ Vd9 ≤ 100; the refractive index and Abbe number of the tenth lens 10 are Nd10 and Vd10, respectively, with Nd10 = 1.80 and 35 ≤ Vd10 ≤ 40; the eleventh lens 1... The refractive index and Abbe number of lens 1 are Nd11 and Vd11, respectively, with Nd11=1.43 and 95≤Vd11≤100; the refractive index and Abbe number of the twelfth lens 12 are Nd12 and Vd12, respectively, with Nd12=1.61 and 40≤Vd12≤45; the refractive index and Abbe number of the thirteenth lens 13 are Nd13 and Vd13, respectively, with Nd13=1.43 and 95≤Vd13≤100.

[0027] This invention utilizes a second lens group 19 and a third lens group 20 to form a synergistic aberration correction structure that corrects first and then compensates. The second lens group 19 employs a negative-positive-negative optical power combination, and through the coordination of different dispersive materials in each lens, it can first suppress axial chromatic aberration and second-order spectral distortion between the visible and near-infrared bands, and control the edge ray deflection angle, thereby reducing spherical aberration and field curvature caused by edge rays under large NA conditions. The ninth lens 9 and the eleventh lens 11 are preferably made of calcium fluoride material, and can be used in combination with other dispersive glasses to further reduce the influence of the second-order spectral distortion.

[0028] The third lens group 20 performs secondary compensation on the beam, and reverses the residual axial chromatic aberration, spherical aberration, field curvature, and focus drift caused by wavelength variation that were not completely eliminated by the second lens group 19, so that the visible light observation band and the 780nm and 1064nm near-infrared processing bands are consistent in the object-side focus position or within the allowable offset range.

[0029] For laser etched wafer dicing, the objective lens not only needs to obtain a clear visible light observation image, but also needs to ensure that the actual focusing position of the near-infrared laser inside the silicon substrate matches the visible light observation positioning position. If the near-infrared processing focus is axially offset relative to the visible light observation focus, it will cause the modification layer or via position inside the wafer to deviate from the predetermined depth, thereby affecting the crack induction path and etched wafer quality. This invention corrects the axial offset of the near-infrared processing focus relative to the visible light observation focus through the second lens group 19 and the third lens group 20, rather than simply performing broadband chromatic aberration correction as in ordinary microscopic imaging objectives, so as to keep the observation positioning focus matched with the laser etched wafer processing focus and ensure the quality of the wafer laser etched wafer dicing through the objective lens.

[0030] The fourth lens group 21 of the present invention includes a fourteenth lens 14, a fifteenth lens 15 and a sixteenth lens 16 arranged sequentially along the optical path direction. The fourteenth lens 14 is a positive optical power biconvex lens, the fifteenth lens 15 is a positive optical power meniscus lens and the sixteenth lens 16 is a positive optical power meniscus lens.

[0031] The focal length of the fourteenth lens 14 satisfies 74 ≤ f14 ≤ 75; the focal length of the fifteenth lens 15 satisfies 64 ≤ f15 ≤ 65; and the focal length of the sixteenth lens 16 satisfies 35 ≤ f16 ≤ 36. The refractive index and Abbe number of the fourteenth lens 14 are Nd14 and Vd14, respectively, with Nd14 = 1.63 and 55 ≤ Vd14 ≤ 60; the refractive index and Abbe number of the fifteenth lens 15 are Nd15 and Vd15, respectively, with Nd15 = 1.63 and 55 ≤ Vd15 ≤ 60; and the refractive index and Abbe number of the sixteenth lens 16 are Nd16 and Vd16, respectively, with Nd16 = 1.81 and 30 ≤ Vd16 ≤ 35. As a preferred option, to protect the objective lens during processing, a seventeenth lens 17 is provided behind the sixteenth lens 16. The seventeenth lens 17 is a flat protective glass, which is set at the front end of the objective lens to block debris, contaminants or splashes generated during laser processing, thereby reducing the risk of damage to internal optical components.

[0032] The working wavelengths of the objective lens provided in this embodiment of the invention include visible light (487 nm to 656 nm), near-infrared (780 nm ± 10 nm), and near-infrared (1064 nm ± 10 nm); its total optical length is preferably 100 mm, its total focal length is preferably 4 mm, its numerical aperture (NA) is preferably 0.67, its resolution is preferably 0.41 μm, and its working distance is preferably 10 mm.

[0033] The specific parameters are shown in Table 1: Table 1: Objective Lens Parameter Table

[0034] The surface number is assigned along the optical path in the order from the first lens 1 to the seventeenth lens 17. For example, the surface number of the first lens 1 is S01 and S02. The thickness represents the distance from the current surface to the next surface. For example, the thickness of S01 represents the distance between surface S01 and surface S02, and the thickness of S02 represents the distance between surface S02 and surface S03. A thickness of 0 indicates that the two surfaces are cemented together. For example, the thickness of surface S10 of the fifth lens 5 is 0, which means that the fifth lens 5 and the sixth lens 6 are cemented together to form a double cemented lens group.

[0035] The objective lens structure of this invention can effectively maintain high spatial resolution and stable focusing quality in the designed wavelength band, which is beneficial for achieving high-precision hidden cutting of short-pulse infrared lasers inside silicon substrates.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A large numerical aperture, long working distance apochromatic microscope objective, characterized in that, The microscope objective consists of 16 lenses, including a first lens group (18), a second lens group (19), a third lens group (20), and a fourth lens group (21) arranged sequentially from the image plane to the object plane along the optical path. The first lens group (18) is used to converge the beam and correct higher-order aberrations, and the fourth lens group (21) is used to correct spherical aberration and field curvature aberration. The second lens group (19) and the third lens group (20) are both cemented triplet lens groups. The second lens group (19) adopts a negative-positive-negative optical power combination, including an eighth lens (8), a ninth lens (9), and a tenth lens (10) arranged sequentially along the optical path. The third lens group (20) adopts a positive-negative-positive optical power combination, including an eleventh lens (11), a twelfth lens (12), and a thirteenth lens (13) arranged sequentially along the optical path. The eighth lens (8) is a negative optical power plano-concave lens, the ninth lens (9) is a positive optical power biconvex lens, the tenth lens (10) is a negative optical power meniscus lens, the eleventh lens (11) is a positive optical power biconvex lens, the twelfth lens (12) is a negative optical power biconcave lens, and the thirteenth lens (13) is a positive optical power biconvex lens. The first lens group (18) includes a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), a sixth lens (6) and a seventh lens (7) arranged sequentially along the optical path. The first lens (1) is a negative optical power biconcave lens, the second lens (2) is a positive optical power meniscus lens, the third lens (3) is a positive optical power biconvex lens, the fourth lens (4) is a negative optical power biconcave lens, the fifth lens (5) is a negative optical power biconcave lens, the sixth lens (6) is a positive optical power biconvex lens, and the seventh lens (7) is a positive optical power biconvex lens. The focal length of the first lens (1) satisfies -12≤f1≤-11; the focal length of the second lens (2) satisfies 16≤f2≤17; the focal length of the third lens (3) satisfies 14≤f3≤15; the focal length of the fourth lens (4) satisfies -10≤f4≤-9; the focal length of the fifth lens (5) satisfies -7≤f5≤-6; the focal length of the sixth lens (6) satisfies 11≤f6≤12; and the focal length of the seventh lens (7) satisfies 26≤f7≤27. The focal length unit is millimeters. The fourth lens group (21) includes a fourteenth lens (14), a fifteenth lens (15) and a sixteenth lens (16) arranged sequentially along the optical path. The fourteenth lens (14) is a positive optical power biconvex lens, the fifteenth lens (15) is a positive optical power meniscus lens, and the sixteenth lens (16) is a positive optical power meniscus lens.

2. The apochromatic microscope objective with a large numerical aperture and long working distance according to claim 1, characterized in that, The focal length of the eighth lens (8) satisfies -19≤f8≤-18; the focal length of the ninth lens (9) satisfies 18≤f9≤19; the focal length of the tenth lens (10) satisfies -32≤f10≤-31; the focal length of the eleventh lens (11) satisfies 33≤f11≤34; and the focal length of the twelfth lens (12) satisfies -22≤f12≤-21. The focal length unit is millimeters.

3. The apochromatic microscope objective with a large numerical aperture and long working distance according to claim 1, characterized in that, The refractive index and Abbe number of the eighth lens (8) are Nd8 and Vd8, respectively, Nd8=1.79, 25≤Vd8≤30; The refractive index and Abbe number of the ninth lens (9) are Nd9 and Vd9, respectively, Nd9=1.43, 95≤Vd9≤100; The refractive index and Abbe number of the tenth lens (10) are Nd10 and Vd10, respectively, Nd10=1.80, 35≤Vd10≤40; The refractive index and Abbe number of the eleventh lens (11) are Nd11 and Vd11, respectively, Nd11=1.43, 95≤Vd11≤100; The refractive index and Abbe number of the twelfth lens (12) are Nd12 and Vd12, respectively, Nd12=1.61, 40≤Vd12≤45; The refractive index and Abbe number of the thirteenth lens (13) are Nd13 and Vd13, respectively, Nd13=1.43, 95≤Vd13≤100.

4. The apochromatic microscope objective with a large numerical aperture and long working distance according to claim 1, characterized in that, The refractive index and Abbe number of the first lens (1) are Nd1 and Vd1, respectively, Nd1=1.59, 65≤Vd1≤70; The refractive index and Abbe number of the second lens (2) are Nd2 and Vd2, respectively, Nd2=1.73, 50≤Vd2≤55; The refractive index and Abbe number of the third lens (3) are Nd3 and Vd3, respectively, Nd3=1.81, 25≤Vd3≤30; The refractive index and Abbe number of the fourth lens (4) are Nd4 and Vd4, respectively, Nd4=1.59, 65≤Vd4≤70; The refractive index and Abbe number of the fifth lens (5) are Nd5 and Vd5, respectively, Nd5=1.95, 30≤Vd5≤35; The refractive index and Abbe number of the sixth lens (6) are Nd6 and Vd6, respectively, Nd6=1.73, 25≤Vd6≤30; The refractive index and Abbe number of the seventh lens (7) are Nd7 and Vd7, respectively, Nd7=1.46, 90≤Vd7≤95.

5. The apochromatic microscope objective with a large numerical aperture and long working distance according to claim 1, characterized in that, The focal length of the fourteenth lens (14) satisfies 74≤f14≤75; the focal length of the fifteenth lens (15) satisfies 64≤f15≤65; and the focal length of the sixteenth lens (16) satisfies 35≤f16≤36. The focal length unit is millimeters.

6. The apochromatic microscope objective with a large numerical aperture and long working distance according to claim 1, characterized in that, The refractive index and Abbe number of the fourteenth lens (14) are Nd14 and Vd14, respectively, Nd14=1.63, 55≤Vd14≤60; The refractive index and Abbe number of the fifteenth lens (15) are Nd15 and Vd15, respectively, Nd15=1.63, 55≤Vd15≤60; The refractive index and Abbe number of the sixteenth lens (16) are Nd16 and Vd16, respectively, Nd16=1.81, 30≤Vd16≤35.

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