A large field of view flat-field telecentric microscope objective

Abstract

The invention discloses a large-field flat-field telecentric microscope objective lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in sequence along the optical axis from the image side to the object side, wherein the first lens is a negative meniscus lens with negative optical power; the second lens is a negative double-cemented lens with negative optical power; the third lens is a positive biconvex lens with positive optical power; the fourth lens is a positive double-cemented lens with positive optical power; the fifth lens is a positive meniscus lens with positive optical power; the sixth lens is a positive meniscus lens with positive optical power; the seventh lens is a negative biconcave lens with negative optical power; and the eighth lens is a positive meniscus lens with positive optical power. The invention satisfies the large field of view while well ensuring the quality of imaging, and effectively improves the application scope of the microscope objective lens system.

Description

Technical Field

[0001] The invention relates to the technical field of optical instruments and equipment, and more particularly to a large-field flat-field telecentric microscope objective. Background Art

[0002] In recent years, due to the rapid development of industrial engineering technology, the structure and purity inspection of industrial materials, defect detection on the device surface, micron-level measurement, real-time microscopic observation, etc., all require optical microscopes to have a larger field of view, which makes the research on large-field microscopes very important.

[0003] In the field of microscopic imaging, the field of view is particularly important. A good objective lens structure has a far-reaching impact on the effect of microscope imaging. Ordinary microscope objectives cannot have both field of view and resolution. Improving the imaging quality of the objective lens is very important for the entire microscopic system. Here, the resolution of the microscopic system mainly depends on the diffraction limit of the objective lens, so the design of the objective lens is a crucial part of the entire microscopic system. Therefore, further improving the imaging quality and field of view of the microscope objective lens is of great significance to research in various fields.

[0004] With the development of science and technology, people are constantly pursuing larger and larger fields of view and higher and higher resolution. Today, optical microscopes play an important role in many fields such as biomedicine. In the 20th century, the resolution of optical microscopes has reached the nanometer scale. Now there are more and more applications that use microscopes for observations in a large field of view, and increasing the field of view of the microscope objective while having a higher resolution is the key to the design of microscope objective lenses in the future.

[0005] Therefore, how to provide a microscope objective lens with a large field of view and high resolution is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] In view of this, the present invention provides a large-field-of-view flat-field telecentric microscope objective lens, which satisfies the requirement of a large field of view while well ensuring the quality of imaging, and effectively improves the application scope of the microscope objective lens system.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A large field of view flat field telecentric microscope objective lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens sequentially arranged along the optical axis from the image side to the object side. The first lens is a negative meniscus lens with a negative focal power; the second lens is a negative doublet lens with a negative focal power; the third lens is a positive biconvex lens with a positive focal power; the fourth lens is a positive doublet lens with a positive focal power; the fifth lens is a positive meniscus lens with a positive focal power; the sixth lens is a positive meniscus lens with a positive focal power; the seventh lens is a negative biconcave lens with a negative focal power; the eighth lens is a positive meniscus lens with a positive focal power.

[0009] Preferably, both surfaces of the first lens are convex towards the object side. The focal length of the first lens is f1, and the focal length of the microscope objective lens is EFL. The focal length of the first lens satisfies -12 < f1 / EFL < -14.

[0010] Preferably, three surfaces of the second lens are convex towards the object side. The focal length of the second lens is f2, and the focal length of the microscope objective lens is EFL. The focal length of the second lens satisfies -24 < f2 / EFL < -26, where the exit surface S3 and the cemented surface S4 form a negative meniscus lens with a negative focal power, and the cemented surface S4 and the entrance surface S5 form a positive meniscus lens with a positive focal power.

[0011] Preferably, the exit surface S6 of the third lens is convex towards the image side, and the entrance surface S7 is convex towards the object side. The focal length of the third lens is f3, and the focal length of the microscope objective lens is EFL. The focal length of the third lens satisfies 3.2 < f3 / EFL < 3.8.

[0012] Preferably, three surfaces of the fourth lens are convex towards the image side. The focal length of the fourth lens is f4, and the focal length of the microscope objective lens is EFL. The focal length of the fourth lens satisfies 14 < f4 / EFL < 15.6, where the exit surface S8 and the cemented surface S9 form a positive meniscus lens with a positive focal power, and the cemented surface S9 and the entrance surface S10 form a negative meniscus lens with a negative focal power.

[0013] Preferably, both surfaces of the fifth lens are convex towards the image side. The focal length of the fifth lens is f5, and the focal length of the microscope objective lens is EFL. The focal length of the fifth lens satisfies 3.36 < f5 / EFL < 4.

[0014] Preferably, both surfaces of the sixth lens are convex towards the image side. The focal length of the sixth lens is f6, and the focal length of the microscope objective lens is EFL. The focal length of the sixth lens satisfies 4.3 < f6 / EFL < 5.2.

[0015] Preferably, the exit surface of the seventh lens is concave toward the image side, the incident surface is concave toward the object side, the focal length of the seventh lens is f7, the focal length of the microscope objective lens is EFL, and the focal length of the seventh lens satisfies -1.2 <f7 / EFL<-1.8。

[0016] Preferably, the double-sided convex surface of the eighth lens is toward the image side, the focal length of the eighth lens is f8, the focal length of the microscope objective lens is EFL, and the focal length of the eighth lens satisfies 2 <f8 / EFL<2.5。

[0017] Preferably, the angle between the principal ray of the object plane and the object plane in the full field of view of the microscope objective is less than 0.2°, and the diameter of the object field of view is not less than 20 mm.

[0018] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a large-field-of-view flat-field telecentric microscope objective lens, which solves the problem of the small field of view of a microscope with NA=0.25, thereby meeting the needs of various fields for the field of view of a microscope objective lens. Moreover, the microscope objective lens of the present invention all adopts spherical lenses, which can be fully realized under the existing processing and detection technology, and has a simple structure, reasonable design, and is easy to manufacture, meeting the requirements of mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0020] Figure 1 The accompanying drawing is a schematic diagram of the structure of a large-field flat-field telecentric microscope objective provided by 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.

[0022] Figure 2 1 is a transfer function curve diagram of a large field of view flat-field telecentric microscope objective lens implementing the present invention. In the figure, the ordinate is the value of the optical transfer function (MTF), and the abscissa is the spatial frequency. It can be seen from the figure that the optical transfer function curve is close to the diffraction limit, indicating that the flat-field microscope objective lens has excellent imaging quality.

[0023] Figure 3 The spot diagram of a large-field flat-field telecentric microscope objective lens implementing the present invention is shown above. It can be seen that most of the light in each field of view is within the range of the Airy disk.

[0024] Figure 4 This is a light fan diagram of a large-field flat-field telecentric microscope objective lens implementing the present invention. The ordinate in the diagram is the distance that the light deviates from the center on the image plane, and the abscissa represents the distance of the light from the center of the aperture stop. It can be seen that the optical system has a good characteristic curve.

[0025] FIG5 is a field curvature graph (a) and a distortion graph (b) of a large field of view flat-field telecentric microscope objective lens implementing the present invention. FIG5(a) is a field curvature graph, wherein the ordinate is the field of view, and the abscissa is the deviation of the meridian light and the sagittal light; FIG5(b) is a distortion graph, wherein the ordinate is the field of view, and the abscissa is the distortion ratio. In a general optical imaging system, as long as the image deformation caused by the distortion is not noticeable to the human eye, the distortion amount is allowable, and the allowable distortion value is about 4%. As shown in FIG5(b), the distortion is less than 1%, which is within the allowable range, so the distortion has been effectively corrected. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The embodiment of the present invention discloses a large-field flat-field telecentric microscope objective lens, which is used in conjunction with a tube lens. Figure 1 As shown, it 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, a seventh lens 7 and an eighth lens 8 which are arranged in sequence along the optical axis from the image side to the object side. The first lens 1 is a negative meniscus lens with negative optical power; the second lens 2 is a negative doublet lens with negative optical power; the third lens 3 is a positive biconvex lens with positive optical power; the fourth lens 4 is a positive doublet lens with positive optical power; the fifth lens 5 is a positive meniscus lens with positive optical power; the sixth lens 6 is a positive meniscus lens with positive optical power; the seventh lens 7 is a negative biconcave lens with negative optical power; and the eighth lens 8 is a positive meniscus lens with positive optical power.

[0028] As a specific embodiment, both sides of the first lens 1 are convex towards the object side, including an incident surface S2 and an exit surface S1. The S1 surface is simultaneously the aperture stop surface. The radius of curvature of the S1 surface is -89.338 mm ± 0.8 mm, the radius of curvature of the S2 surface is -121.165 mm ± 0.321 mm, and the thickness of the first lens 1 is 25.2 mm ± 0.27 mm, that is, the distance between the centers of the S1 surface and the S2 surface. The refractive index / Abbe number of the material is 1.8 / 44.28. The gap between the center of the incident surface of the first lens and the center of the exit surface of the second lens 2 is 21 mm ± 0.2 mm. The focal length of the first lens 1 is f1, and the focal length of the microscope lens is EFL. The focal length of the first lens 1 satisfies -12 < f1 / EFL < -14, and the preferred focal length is -650.7 mm.

[0029] As a specific embodiment, three sides of the second lens 2 are convex towards the object side. The radius of curvature of the S3 surface is -55.46 mm ± 0.25 mm, and the radius of curvature of the S4 surface is -272.9 mm ± 0.3 mm. Among them, S3 and S4 form a negative-power meniscus lens, and the thickness is 25.0 mm ± 0.2 mm. The refractive index / Abbe number of the material is 1.64 / 34.47. The radius of curvature of the S5 surface is -106.17 mm ± 0.3 mm, and S4 and S5 form a positive-power meniscus lens, and the thickness is 19 mm ± 0.15 mm. The refractive index / Abbe number of the material is 2 / 25.43. The gap between the center of the incident surface of the second lens and the center of the exit surface of the third lens 3 is 2 mm ± 0.05 mm. The focal length of the second lens 2 is f2, and the focal length of the microscope lens is EFL. The focal length of the second lens satisfies -24 < f2 / EFL < -26, and the preferred focal length is -1252.6 mm.

[0030] As a specific embodiment, the exit surface S6 of the third lens 3 is convex towards the image side, and the incident surface S7 is convex towards the object side. The radius of curvature of the S6 surface is 295.1 mm ± 1.2 mm, and the radius of curvature of the S7 surface is -485.3 mm ± 0.6 mm. The thickness of the third lens 3 is 8.6 mm ± 0.2 mm, that is, the distance between the centers of the S6 surface and the S7 surface. The refractive index / Abbe number of the material is 2 / 25.43. The gap between the center of the incident surface of the third lens and the center of the exit surface of the fourth lens 4 is 2 mm ± 0.1 mm. The focal length of the third lens 3 is f3, and the focal length of the microscope lens is EFL. The focal length of the third lens 3 satisfies 3.2 < f3 / EFL < 3.8, and the preferred focal length is 182 mm.

[0031] As a specific embodiment, three surfaces of the fourth lens 4 are convex toward the image side. The radius of curvature of the S8 surface is 73.7 mm ± 0.2 mm, the radius of curvature of the S9 surface is 138 mm ± 2.2 mm. Among them, S8 and S9 form a meniscus lens with positive optical power, and the thickness is 18.3 mm ± 0.2 mm. The refractive index / Abbe number of the material is 2 / 25.43. The radius of curvature of the S10 surface is -47.75 mm ± 0.15 mm. S9 and S10 form a meniscus lens with negative optical power, and the thickness is 18.9 mm ± 0.22 mm. The refractive index / Abbe number of the material is 1.64 / 34.5. The gap between the center of the incident surface of the fourth lens and the center of the exit surface of the fifth lens 5 is 4.3 mm ± 0.13 mm. The focal length of the fourth lens 4 is f4, and the focal length of the microscope lens is EFL. The focal length of the fourth lens 4 satisfies 14 < f4 / EFL < 15.6, and the preferred focal length is 745.8 mm.

[0032] As a specific embodiment, both surfaces of the fifth lens 5 are convex toward the image side, including the incident surface S12 and the exit surface S11. The radius of curvature of the S11 surface is 61.66 mm ± 0.52 mm, and the radius of curvature of the S12 surface is 83 mm ± 0.2 mm. The thickness of the fifth lens is 25 mm ± 1 mm, that is, the distance between the center of the S11 surface and the center of the S12 surface. The refractive index / Abbe number of the material is 1.8 / 22.69. The gap between the center of the incident surface of the fifth lens and the center of the exit surface of the sixth lens 6 is 2 mm ± 0.08 mm. The focal length of the fifth lens 5 is f5, and the focal length of the microscope lens is EFL. The focal length of the fifth lens 5 satisfies 3.36 < f5 / EFL < 4, and the preferred focal length is 191.5 mm.

[0033] As a specific embodiment, both surfaces of the sixth lens 6 are convex toward the image side, including the incident surface S14 and the exit surface S13. The radius of curvature of the S13 surface is 61.38 mm ± 0.2 mm, and the radius of curvature of the S14 surface is 83 mm ± 0.2 mm. The thickness of the sixth lens 6 is 17 mm ± 0.63 mm, that is, the distance between the center of the S13 surface and the center of the S14 surface. The refractive index / Abbe number of the material is 1.7 / 29.5. The gap between the center of the incident surface of the sixth lens and the center of the exit surface of the seventh lens 7 is 4.3 mm ± 0.2 mm. The focal length of the sixth lens 6 is f6, and the focal length of the microscope lens is EFL. The focal length of the sixth lens 6 satisfies 4.3 < f6 / EFL < 5.2, and the preferred focal length is 243.8 mm.

[0034] As a specific embodiment, the exit surface S15 of the seventh lens 7 is concave towards the image side, the entrance surface S16 is concave towards the object side, the radius of curvature of the S15 surface is -240.6 mm ± 1.6 mm, the radius of curvature of the S16 surface is 114.8 mm ± 2.2 mm, the thickness of the seventh lens 7 is 7.7 mm ± 0.12 mm, that is, the distance between the centers of the S15 surface and the S16 surface, the refractive index / Abbe number of the material is 1.92 / 22.88, the gap between the center of the entrance surface of the seventh lens and the center of the exit surface of the eighth lens 8 is 1.5 mm ± 0.03 mm, the focal length of the seventh lens 7 is f7, the focal length of the microscope lens is EFL, and the focal length of the seventh lens 7 satisfies -1.2 < f7 / EFL < -1.8, preferably the focal length is -82.7 mm.

[0035] As a specific embodiment, both sides of the eighth lens 8 are convex towards the image side, including an entrance surface S18 and an exit surface S17, the radius of curvature of the S17 surface is 40.7 mm ± 0.32 mm, the radius of curvature of the S18 surface is 163.3 mm ± 0.5 mm, the thickness of the eighth lens 8 is 9.4 mm ± 0.56 mm, that is, the distance between the centers of the S17 surface and the S18 surface, the refractive index / Abbe number of the material is 1.47 / 66.88, the focal length of the eighth lens 8 is f8, the focal length of the microscope lens is EFL, and the focal length of the eighth lens 8 satisfies 2 < f8 / EFL < 2.5, preferably the focal length is 112 mm.

[0036] The other parameters of the above examples are as follows:

[0037] The focal length of the large field of view flat field telecentric microscope objective is 50.12 mm, the incident light wavelength is 532 nm ± 0.1 nm, and the maximum numerical aperture is 0.25.

[0038] Figure 2 、 Figure 3 、 Figure 4 Figure 5 proves the superiority of the present invention, which can effectively increase the field of view range of the flat field microscope objective, and maintain a clear imaging effect of the flat field microscope objective in the whole field of view during the optimization process.

[0039] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0040] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A large field of view flat-field telecentric microscope objective lens, characterized in that: It is composed of an eighth lens, a seventh lens, a sixth lens, a fifth lens, a fourth lens, a third lens, a second lens and a first lens arranged in sequence along the optical axis from the image side to the object side. The first lens is a meniscus lens with a negative focal power; the second lens is a cemented doublet lens with a negative focal power; the third lens is a biconvex lens with a positive focal power; the fourth lens is a cemented doublet lens with a positive focal power; the fifth lens is a meniscus lens with a positive focal power; the sixth lens is a meniscus lens with a positive focal power; the seventh lens is a biconcave lens with a negative focal power; the eighth lens is a meniscus lens with a positive focal power.

2. A large field of view flat-field telecentric microscope objective according to claim 1, characterized in that: Both surfaces of the first lens are convex towards the object side. The focal length of the first lens is f1, and the focal length of the microscopic objective is EFL. The focal length of the first lens satisfies -14 < f1 / EFL < -12.

3. A large field of view flat-field telecentric microscope objective according to claim 1, characterized in that: Three surfaces of the second lens are convex towards the object side. The focal length of the second lens is f2, and the overall focal length of the microscopic objective is EFL. The focal length of the second lens satisfies -26 < f2 / EFL < -24, where the exit surface S3 and the cemented surface S4 form a meniscus lens with a negative focal power, and the cemented surface S4 and the entrance surface S5 form a meniscus lens with a positive focal power.

4. A large field of view flat-field telecentric microscope objective lens according to claim 1, characterized in that: The exit surface S6 of the third lens is convex towards the image side, and the entrance surface S7 is convex towards the object side. The focal length of the third lens is f3, and the focal length of the microscopic objective is EFL. The focal length of the third lens satisfies 3.2 < f3 / EFL < 3.

8.

5. A large field of view flat-field telecentric microscope objective lens according to claim 1, characterized in that: Three surfaces of the fourth lens are convex towards the image side. The focal length of the fourth lens is f4, and the focal length of the microscopic objective is EFL. The focal length of the fourth lens satisfies 14 < f4 / EFL < 15.6, where the exit surface S8 and the cemented surface S9 form a meniscus lens with a positive focal power, and the cemented surface S9 and the entrance surface S10 form a meniscus lens with a negative focal power.

6. A large field of view flat-field telecentric microscope objective according to claim 1, characterized in that: Both surfaces of the fifth lens are convex towards the image side. The focal length of the fifth lens is f5, and the focal length of the microscopic objective is EFL. The focal length of the fifth lens satisfies 3.36 < f5 / EFL < 4.

7. A large field of view flat-field telecentric microscope objective according to claim 1, characterized in that: Both surfaces of the sixth lens are convex towards the image side. The focal length of the sixth lens is f6, and the focal length of the microscopic objective is EFL. The focal length of the sixth lens satisfies 4.3 < f6 / EFL < 5.

2.

8. A large field of view flat-field telecentric microscope objective lens according to claim 1, characterized in that: The exit surface of the seventh lens is concave towards the image side, and the entrance surface is concave towards the object side. The focal length of the seventh lens is f7, and the focal length of the microscopic objective is EFL. The focal length of the seventh lens satisfies -1.8 < f7 / EFL < -1.

2.

9. A large field of view flat-field telecentric microscope objective according to claim 1, characterized in that: Both surfaces of the eighth lens are convex towards the image side. The focal length of the eighth lens is f8, and the focal length of the microscopic objective is EFL. The focal length of the eighth lens satisfies 2 < f8 / EFL < 2.

5.

10. A large field of view flat-field telecentric microscope objective lens according to claim 1, characterized in that: The angle between the chief ray of the object surface and the normal of the object surface within the entire field of view of the microscopic objective is less than 0.2°, and the object-side field diameter is not less than 20 mm.

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