Microscope tube lens, microscope, and semiconductor inspection apparatus

Abstract

The utility model provides a kind of microscope tube lens, microscope and semiconductor detection equipment. Wherein microscope tube lens includes: first lens group, second lens group and third lens group are sequentially arranged with optical axis from object side to image side;First lens group, second lens group and third lens group include at least two lenses respectively, and the refractive index of at least two lenses in each lens group is different;First lens group is convex towards object side, and it is convex towards image side;Second lens group is concave towards object side, and it is convex towards image side;Third lens group is concave towards object side, and it is convex towards image side. The utility model, by the parameter and structure of each lens are set, so that the image side field of view of microscope tube lens is 40.3mm, focal length is 200mm, improves imaging quality and image side field of view, and then the overall performance of microscope is promoted;Aberration correction is good, without vignetting;Realize self-design, solve the problem that existing tube lens cannot be well matched with semiconductor detection equipment.

Description

Technical Field

[0001] This utility model relates to the field of microscopes, and in particular to a microscope tube, a microscope, and a semiconductor testing device. Background Technology

[0002] With the rapid development of micro-nano fabrication technology, the feature size of integrated circuits is becoming increasingly smaller. To meet the ever-increasing integration requirements of semiconductor testing equipment, it is essential to use microscope tubes designed specifically for these needs. Currently, some foreign manufacturers can provide standard microscope tubes with image-square fields of view typically of 22mm, 24mm, and 30mm.

[0003] However, these foreign manufacturers do not provide high-order optical parameters for microscope tubes, which makes it impossible to design microscope tubes specifically for semiconductor inspection equipment, affecting system integration and even reducing the imaging quality of the optical system. Furthermore, the image-side field of view of conventional microscope tubes is less than 30mm, which cannot meet the large field-of-view measurement requirements of semiconductor inspection equipment. Utility Model Content

[0004] One objective of this invention is to effectively improve the imaging quality and image-side field of view of a microscope tube, thereby enhancing the overall performance of the microscope.

[0005] A further objective of this invention is to achieve independent design of microscope tubes, enabling microscope tubes to be better matched with semiconductor testing equipment.

[0006] Specifically, this utility model provides a microscope tube, comprising: a first lens group, a second lens group, and a third lens group arranged coaxially from the object side to the image side; the first lens group, the second lens group, and the third lens group each include at least two lenses, and the at least two lenses in each lens group have different refractive indices; the first lens group has a convex surface facing the object side and a convex surface facing the image side; the second lens group has a concave surface facing the object side and a convex surface facing the image side; the third lens group has a concave surface facing the object side and a convex surface facing the image side.

[0007] Optionally, 0.9 < fG1 / f < 1.1, 0.9 < fG2 / f < 1.1, -0.45 < fG3 / f < -0.3, where fG1 is the focal length of the first lens group, fG2 is the focal length of the second lens group, fG3 is the focal length of the third lens group, and f is the focal length of the microscope tube.

[0008] Optionally, the first lens group is a cemented doublet with positive optical power, including a first lens and a second lens starting from the object side; the first lens is convex when facing the object side and convex when facing the image side; the second lens is concave when facing the object side and convex when facing the image side; the second lens group is a cemented doublet with positive optical power, including a third lens and a fourth lens starting from the object side; the third lens is concave when facing the object side and concave when facing the image side; the fourth lens is convex when facing the object side and convex when facing the image side; the third lens group is a cemented doublet with negative optical power, including a fifth lens and a sixth lens starting from the object side; the fifth lens is concave when facing the object side and concave when facing the image side; the sixth lens is convex when facing the object side and convex when facing the image side.

[0009] Optionally, the first and fifth lenses satisfy the following conditions: 1.4 < nd < 1.6, 65 < Vd < 100, and the second, third, fourth, and sixth lenses satisfy the following conditions: 1.6 < nd < 1.9, 30 < Vd < 65, where nd is the refractive index at a wavelength of 587.6 nm and Vd is the Abbe number at a wavelength of 587.6 nm.

[0010] Optionally, the first lens has a refractive index of 1.45 and an Abbe number of 95; the second lens has a refractive index of 1.8 and an Abbe number of 50; the third lens has a refractive index of 1.64 and an Abbe number of 40; the fourth lens has a refractive index of 1.63 and an Abbe number of 34; the fifth lens has a refractive index of 1.55 and an Abbe number of 72; and the sixth lens has a refractive index of 1.66 and an Abbe number of 56.

[0011] Optionally, the object-facing surface of the first lens is the first mirror surface, the cemented surface of the first and second lenses is the second mirror surface, and the image-facing surface of the second lens is the third mirror surface; the object-facing surface of the third lens is the fourth mirror surface, the cemented surface of the third and fourth lenses is the fifth mirror surface, and the image-facing surface of the fourth lens is the sixth mirror surface; the object-facing surface of the fifth lens is the seventh mirror surface, the cemented surface of the fifth and sixth lenses is the eighth mirror surface, and the image-facing surface of the sixth lens is the ninth mirror surface; the radii of curvature of the first, fifth, and eighth mirror surfaces are positive; and the radii of curvature of the second, third, fourth, sixth, seventh, and ninth mirror surfaces are negative.

[0012] Optionally, the radius of curvature of the first mirror is 65mm, and the mirror distance between the first and second mirrors is 10mm; the radius of curvature of the second mirror is -40mm, and the mirror distance between the second and third mirrors is 1mm; the radius of curvature of the third mirror is -120mm, and the mirror distance between the third and fourth mirrors is 10mm; the radius of curvature of the fourth mirror is -80mm, and the mirror distance between the fourth and fifth mirrors is 2.5mm; the radius of curvature of the fifth mirror is 200mm. The mirror distance between the fifth and sixth mirrors is 8mm; the radius of curvature of the sixth mirror is -50mm, and the mirror distance between the sixth and seventh mirrors is 64mm; the radius of curvature of the seventh mirror is -40mm, and the mirror distance between the seventh and eighth mirrors is 2mm; the radius of curvature of the eighth mirror is 200mm, and the mirror distance between the eighth and ninth mirrors is 2mm; the radius of curvature of the ninth mirror is -220mm, and the mirror distance between the ninth mirror and the image plane is 65mm.

[0013] According to another aspect of the present invention, a microscope is also provided, comprising any of the microscope tubes described above.

[0014] According to another aspect of the present invention, a semiconductor detection device is also provided, including the microscope described above.

[0015] The microscope tube of this invention, by setting the specific parameters and structure of each lens, achieves an image-side field of view of 40.3mm and a focal length of 200mm. While improving the imaging quality, it also provides an image-side field of view that is higher than that of conventional tubes, which can meet the large field-of-view measurement requirements of semiconductor testing equipment and improve the overall performance of the microscope.

[0016] Furthermore, the microscope tube of this invention has good aberration correction and no vignetting; and it is completely independently designed, solving the problem that existing tubes cannot be well matched with semiconductor detection equipment.

[0017] The above and other objects, advantages and features of this utility model will become more apparent to those skilled in the art from the following detailed description of specific embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0018] The following sections will describe some specific embodiments of the present invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0019] Figure 1 This is a schematic diagram of the structure of a microscope tube according to an embodiment of the present invention;

[0020] Figure 2 This is a full-field, full-wavelength dot plot of a microscope tube according to an embodiment of the present invention;

[0021] Figure 3 This is a full-field transfer function curve of a microscope tube according to an embodiment of the present invention;

[0022] Figure 4 This is a full-field, non-vignetting ray fraction diagram of a microscope tube according to an embodiment of the present invention; and

[0023] Figure 5 This is a field distortion diagram of a microscope tube according to an embodiment of the present invention. Detailed Implementation

[0024] This embodiment provides a microscope tube that can effectively improve the imaging quality and image-side field of view of the microscope tube, thereby enhancing the overall performance of the microscope. Figure 1 This is a schematic diagram of the structure of a microscope tube according to an embodiment of the present invention. Figure 1 As shown, the microscope tube of this embodiment includes: a first lens group G1, a second lens group G2, and a third lens group G3 arranged coaxially from the object side to the image side.

[0025] The first lens group G1, the second lens group G2, and the third lens group G3 each include at least two lenses, and the at least two lenses in each lens group have different refractive indices. The first lens group G1 has a convex surface facing both the object side and the image side; the second lens group G2 has a concave surface facing both the object side and the image side; and the third lens group G3 has a concave surface facing both the object side and the image side.

[0026] In one specific embodiment, 0.9 < fG1 / f < 1.1, 0.9 < fG2 / f < 1.1, -0.45 < fG3 / f < -0.3, where fG1 is the focal length of the first lens group G1, fG2 is the focal length of the second lens group G2, fG3 is the focal length of the third lens group G3, and f is the focal length of the microscope tube.

[0027] In a preferred embodiment, the first lens group G1 is a cemented doublet lens with positive optical power, including a first lens L1 and a second lens L2 starting from the object side; the first lens L1 has a convex surface facing both the object and image sides; the second lens L2 has a concave surface facing both the object and image sides. Positive optical power refers to the optical power of an optical system that converges light rays, and its value is greater than zero. An optical system with positive optical power converges light rays, meaning that the light beam becomes more focused after passing through the system. A cemented doublet lens is a combined lens formed by cementing two lenses together, achieving better imaging results through the combination of the two lenses. Compared to a single lens, a cemented doublet lens can achieve a shorter focal length, greater magnification, better image quality, and higher axial resolution.

[0028] The second lens group G2 is a cemented doublet with positive optical power, including a third lens L3 and a fourth lens L4 starting from the object side; the third lens L3 is concave when facing the object side and concave when facing the image side; the fourth lens L4 is convex when facing the object side and convex when facing the image side.

[0029] The third lens group G3 is a cemented doublet with negative optical power, consisting of a fifth lens L5 and a sixth lens L6 starting from the object side; the fifth lens L5 is concave when facing the object side and concave when facing the image side; the sixth lens L6 is convex when facing the object side and convex when facing the image side. An optical system with negative optical power makes light rays more divergent, meaning that the light beam becomes more dispersed after passing through this system.

[0030] In one specific embodiment, the first lens L1 and the fifth lens L5 both satisfy the following conditions: 1.4 < nd < 1.6, 65 < Vd < 100, and the second lens L2, the third lens L3, the fourth lens L4, and the sixth lens L6 all satisfy the following conditions: 1.6 < nd < 1.9, 30 < Vd < 65, where nd is the refractive index at a wavelength of 587.6 nm and Vd is the Abbe number at a wavelength of 587.6 nm.

[0031] In a preferred embodiment, the specific values ​​of the refractive index and Abbe number of the first lens L1 to the sixth lens L6 can be referred to Table 1. As shown in Table 1, the refractive index of the first lens L1 is 1.45 and the Abbe number is 95; the refractive index of the second lens L2 is 1.8 and the Abbe number is 50; the refractive index of the third lens L3 is 1.64 and the Abbe number is 40; the refractive index of the fourth lens L4 is 1.63 and the Abbe number is 34; the refractive index of the fifth lens L5 is 1.55 and the Abbe number is 72; and the refractive index of the sixth lens L6 is 1.66 and the Abbe number is 56.

[0032] Table 1

[0033]

[0034]

[0035] In one specific embodiment, the object-facing surface of the first lens L1 is the first mirror surface S1, the cemented surface of the first lens L1 and the second lens L2 is the second mirror surface S2, and the image-facing surface of the second lens L2 is the third mirror surface S3. The object-facing surface of the third lens L3 is the fourth mirror surface S4, the cemented surface of the third lens L3 and the fourth lens L4 is the fifth mirror surface S5, and the image-facing surface of the fourth lens L4 is the sixth mirror surface S6. The object-facing surface of the fifth lens L5 is the seventh mirror surface S7, the cemented surface of the fifth lens L5 and the sixth lens L6 is the eighth mirror surface S8, and the image-facing surface of the sixth lens L6 is the ninth mirror surface S9.

[0036] Furthermore, the radii of curvature of the first mirror S1, the fifth mirror S5, and the eighth mirror S8 are positive; while the radii of curvature of the second mirror S2, the third mirror S3, the fourth mirror S4, the sixth mirror S6, the seventh mirror S7, and the ninth mirror S9 are negative.

[0037] In a preferred embodiment, the specific values ​​of the radii of curvature of the first mirror S1 to the ninth mirror S9 and the mirror distance between two adjacent mirrors can be referred to Table 2. As shown in Table 2, the radius of curvature of the first mirror S1 is 65mm, and the mirror distance between the first mirror S1 and the second mirror S2 is 10mm; the radius of curvature of the second mirror S2 is -40mm, and the mirror distance between the second mirror S2 and the third mirror S3 is 1mm; the radius of curvature of the third mirror S3 is -120mm, and the mirror distance between the third mirror S3 and the fourth mirror S4 is 10mm; the radius of curvature of the fourth mirror S4 is -80mm, and the mirror distance between the fourth mirror S4 and the fifth mirror S5 is 2.5mm; the radius of curvature of the fifth mirror S5 is 200mm. m, the mirror distance between the fifth mirror S5 and the sixth mirror S6 is 8mm; the radius of curvature of the sixth mirror S6 is -50mm, the mirror distance between the sixth mirror S6 and the seventh mirror S7 is 64mm; the radius of curvature of the seventh mirror S7 is -40mm, the mirror distance between the seventh mirror S7 and the eighth mirror S8 is 2mm; the radius of curvature of the eighth mirror S8 is 200mm, the mirror distance between the eighth mirror S8 and the ninth mirror S9 is 2mm; the radius of curvature of the ninth mirror S9 is -220mm, the mirror distance between the ninth mirror S9 and the image plane is 65mm.

[0038] Table 2

[0039]

[0040]

[0041] By setting the specific parameters and structures of each lens according to Tables 1 and 2 above, the image-side field of view of the microscope tube can be 40.3 mm, and the focal length can be 200 mm. The microscope tube of this embodiment improves the imaging quality, has a higher image-side field of view than conventional tubes, and is completely independently designed, solving the problem that existing tubes cannot be well matched with semiconductor detection equipment.

[0042] Figure 2 This is a full-field, full-wavelength dot plot of a microscope tube according to an embodiment of the present invention. Figure 2 The focusing of light with wavelengths from 0.4 μm to 0.7 μm at the focal point is shown under different image plane fields of view. The image plane half field of view of field of view (1) is 0 mm, the image plane half field of view of field of view (2) is 10.017 mm, and the image plane half field of view of field of view (3) is 20.15 mm. Therefore, the image plane fields of view corresponding to fields of view (1), (2), and (3) are 0 mm, 20.034 mm, and 40.3 mm, respectively. The test data are as follows: Airy disk radius (diffraction limit) is 13.505 μm, RMS radius (root mean square) at field of view (1) is 0.596 μm, GEO radius (maximum) is 1.501 μm, RMS radius at field of view (2) is 0.657 μm, GEO radius is 1.454 μm, RMS radius at field of view (3) is 0.643 μm, GEO radius is 1.423 μm.

[0043] The RMS radius, also known as the root mean square spot radius, is an indicator used to describe the size of a light beam. It is the spot radius obtained by taking the square root of the second average of the light intensity distribution. The GEO radius (Geometric Optical Radius) represents the radius of the smallest central circle that contains all light rays. Specifically, the GEO radius is the radius of the smallest central circle that allows all light rays to fall within its range. Figure 2 It can be seen that the focused light spots of different wavelengths of light in different fields of view are all within the Airy disk range, and the dot plots are all better than the diffraction limit, indicating that the image aberration of the microscope tube in this embodiment is well controlled and basically reaches the system limit.

[0044] Figure 3 This is a full-field transfer function curve of a microscope tube according to an embodiment of the present invention. Figure 3 The ordinate represents the magnitude of the normalized transfer function, and the abscissa represents the spatial frequency, with units of lp / mm. The outermost line is the transfer function curve of the system under diffraction-limited conditions. For example... Figure 3As shown, in this embodiment of the microscope tube, when the image plane field of view is 0mm, 20.034mm and 40.3mm, the transfer function curves of the meridional plane and the sagittal plane at each wavelength show that the on-axis field of view transfer function curve and the off-axis field of view transfer function curve are close to the diffraction limit, indicating that the imaging contrast of the optical system across the entire field of view is very high and the imaging layering is distinct.

[0045] Figure 4 This is a full-field, un-vignetted ray fraction diagram of a microscope tube according to an embodiment of the present invention. Figure 4 The horizontal axis represents the field of view, and the vertical axis represents the fraction of un-vignetted rays. Figure 4 The illustration shows that the fraction of non-vignetting rays in the entire field of view of the microscope tube in this embodiment is 1, indicating that the microscope tube has no vignetting in the entire field of view and the imaging brightness is uniform.

[0046] Figure 5 This is a field distortion diagram of a microscope tube according to an embodiment of the present invention. Figure 5 The left side of the graph is the field curvature diagram. The vertical axis represents the field of view in the direction of the incident light from the tube, and the horizontal axis represents the field curvature value, in mm. Figure 5 The right-hand side of the graph shows the distortion plot. The vertical axis represents the image-side field of view during imaging, and the horizontal axis represents the distortion percentage. The data obtained when testing the field curvature plot are as follows: maximum field of view 4mm, sagittal field curvature 0.0401mm, meridional field curvature 0.0794mm. The data obtained when testing the distortion plot are as follows: maximum field of view 4mm, maximum distortion 0.7442%. Figure 5 As shown, the field curvature values ​​in both the meridional and sagittal planes at each wavelength are below 0.12 mm, resulting in clear imaging across the entire field of view without introducing additional field curvature. The distortion across the entire field of view at each wavelength is within 0.8%, indicating good distortion correction and excellent large field-of-view imaging performance.

[0047] This embodiment also provides a microscope, which includes the microscope tube of any of the above embodiments. Furthermore, this embodiment also provides a semiconductor inspection device, which includes the aforementioned microscope. In a specific embodiment, by setting the specific parameters and structure of each lens, the image-side field of view of the microscope tube is made 40.3mm, and the focal length is 200mm. This improves image quality while providing a higher image-side field of view than conventional tubes, meeting the large field-of-view measurement requirements of semiconductor inspection equipment and enhancing the overall performance of the microscope. The microscope tube has good aberration correction and no vignetting; moreover, it is entirely independently designed, solving the problem that existing tubes cannot be well matched with semiconductor inspection equipment.

[0048] Those skilled in the art should understand that, unless otherwise specified, the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "clockwise," and "counterclockwise" used to indicate orientation or positional relationships in the embodiments of this utility model are merely for the convenience of describing and understanding the technical solution of this utility model, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0049] The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," etc., may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0050] Unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "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, unless otherwise expressly limited. Those skilled in the art should be able to understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0051] Furthermore, in the description of this embodiment, "above" or "below" the second feature can include direct contact between the first and second features, or it can include contact between the first and second features through another feature between them. That is, in the description of this embodiment, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "below" of the second feature can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0052] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0053] Therefore, those skilled in the art should recognize that although many exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A microscope endpiece, characterized in that, include: The first lens group, the second lens group, and the third lens group are arranged coaxially from the object side to the image side; The first lens group, the second lens group, and the third lens group each include at least two lenses, and the at least two lenses in each lens group have different refractive indices; The first lens group has a convex surface facing both the object and image sides; the second lens group has a concave surface facing both the object and image sides; and the third lens group has a concave surface facing both the object and image sides.

2. The microscope tube according to claim 1, characterized in that, 0.9 < fG1 / f < 1.1, 0.9 < fG2 / f < 1.1, -0.45 < fG3 / f < -0.3, where fG1 is the focal length of the first lens group, fG2 is the focal length of the second lens group, fG3 is the focal length of the third lens group, and f is the focal length of the microscope tube.

3. The microscope tube according to claim 2, characterized in that, The first lens group is a cemented doublet with positive optical power, including a first lens and a second lens starting from the object side; the first lens has a convex surface facing the object side and a convex surface facing the image side; the second lens has a concave surface facing the object side and a convex surface facing the image side. The second lens group is a cemented doublet with positive optical power, including a third lens and a fourth lens starting from the object side; the third lens has a concave surface facing the object side and a concave surface facing the image side; the fourth lens has a convex surface facing the object side and a convex surface facing the image side. The third lens group is a cemented doublet with negative optical power, including a fifth lens and a sixth lens starting from the object side; the fifth lens has a concave surface facing the object side and a concave surface facing the image side; the sixth lens has a convex surface facing the object side and a convex surface facing the image side.

4. The microscope tube according to claim 3, characterized in that, The first lens and the fifth lens both satisfy the following conditions: 1.4 < nd < 1.6, 65 < Vd < 100. The second lens, the third lens, the fourth lens, and the sixth lens all satisfy the following conditions: 1.6 < nd < 1.9, 30 < Vd < 65, where nd is the refractive index at a wavelength of 587.6 nm and Vd is the Abbe number at a wavelength of 587.6 nm.

5. The microscope tube according to claim 4, characterized in that, The first lens has a refractive index of 1.45 and an Abbe number of 95. The second lens has a refractive index of 1.8 and an Abbe number of 50. The third lens has a refractive index of 1.64 and an Abbe number of 40. The fourth lens has a refractive index of 1.63 and an Abbe number of 34. The fifth lens has a refractive index of 1.55 and an Abbe number of 72. The sixth lens has a refractive index of 1.66 and an Abbe number of 56.

6. The microscope tube according to claim 5, characterized in that, The object-facing surface of the first lens is the first mirror surface, the cemented surface of the first lens and the second lens is the second mirror surface, and the image-facing surface of the second lens is the third mirror surface. The object-facing surface of the third lens is the fourth mirror surface, the cemented surface of the third lens and the fourth lens is the fifth mirror surface, and the image-facing surface of the fourth lens is the sixth mirror surface. The object-facing surface of the fifth lens is the seventh mirror surface, the cemented surface of the fifth and sixth lenses is the eighth mirror surface, and the image-facing surface of the sixth lens is the ninth mirror surface. The radii of curvature of the first, fifth, and eighth mirrors are positive; the radii of curvature of the second, third, fourth, sixth, seventh, and ninth mirrors are negative.

7. The microscope tube according to claim 6, characterized in that, The radius of curvature of the first mirror is 65mm, and the mirror distance between the first mirror and the second mirror is 10mm. The radius of curvature of the second mirror is -40mm, and the mirror distance between the second mirror and the third mirror is 1mm; The radius of curvature of the third mirror is -120mm, and the mirror distance between the third mirror and the fourth mirror is 10mm; The radius of curvature of the fourth mirror is -80mm, and the mirror distance between the fourth mirror and the fifth mirror is 2.5mm; The radius of curvature of the fifth mirror is 200mm, and the mirror distance between the fifth mirror and the sixth mirror is 8mm; The radius of curvature of the sixth mirror is -50mm, and the mirror distance between the sixth mirror and the seventh mirror is 64mm; The radius of curvature of the seventh mirror is -40mm, and the mirror distance between the seventh mirror and the eighth mirror is 2mm; The radius of curvature of the eighth mirror is 200mm, and the mirror distance between the eighth mirror and the ninth mirror is 2mm; The radius of curvature of the ninth mirror is -220mm, and the mirror distance between the ninth mirror and the image plane is 65mm.

8. A microscope comprising the microscope tube as described in any one of claims 1 to 7.

9. A semiconductor testing device, comprising the microscope of claim 8.

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