10-time immersion liquid Mirau type interference microscope objective

Abstract

The invention relates to a 10-time immersion liquid Mirau type interference microscope objective, which comprises a cover glass, a first immersion medium, a spectroscope, a second immersion medium, a reflective mirror, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from an object plane to an image plane, the material and parameters of the objective lens structure are specifically designed. The numerical aperture of the microscope objective is 0.3, the focal length is 20 mm, the parfocal distance is 60 mm, the working distance is 10 mm, the object space field of view is 0.68 mm, the first immersion medium and the second immersion medium are both silicone oil, the refractive index of the immersion media is 1.403, the refractive index of the immersion media can be well matched with the refractive index of the human skin in the near-infrared band, and the microscope objective can be applied to the field of view of the human skin. The focal plane of the interference objective lens and the interference plane intersect during measurement, and aberration introduced by the silicone oil and the glass plate is corrected through the lens group at the rear end. The method is good in interference microscopic imaging quality, is suitable for low-coherence interference imaging, and can be well used for realizing three-dimensional imaging of human skin.

Description

Technical Field

[0001] The invention belongs to the field of microscope objective optical system design, in particular to a 10-fold immersion Mirau type interference microscope objective. Background Art

[0002] The statements in this section only provide background information related to the present disclosure, and these statements may constitute prior art. In the process of implementing the present invention, the inventors found that there are at least the following problems in the prior art.

[0003] Skin cancer is the most common cancer in humans. How to correctly identify skin cancer has attracted the attention of researchers from all over the world. Many countries have invested a lot of manpower, material resources, and financial resources in researching it, and many excellent clinically available technologies have emerged one after another, including non-invasive optical imaging technologies such as confocal microscopy (RCM), two-photon luminescence microscopy (TPL), and optical coherence tomography (OCT).

[0004] Optical coherence tomography (OCT) is an optical system that uses image interferometry technology. It provides an excellent imaging technology that can be used to examine cell characteristics and quantify skin structural characteristics. It has been widely used in tissue imaging reconstruction. It relies on low-coherence microscopy and can examine the surface morphology of skin tissue with high precision. However, when the OCT system images biological samples in the air, the following disadvantages will occur: first, after entering the biological sample, there is a mismatch between the coherence plane and the focal plane; second, the reflected light is much larger than the scattered light, which affects the fringe contrast; finally, the dispersion of the two interference arms does not match, affecting the imaging depth and imaging quality.

[0005] Among them, the interference objective is the core component of the OCT system. The structures of interference microscope objective lenses mainly include Linnik type, Mirau type and Michelson type. The Linnik type consists of two identical microscope objective lenses. To solve the above problems, the two interference arms can be immersed in a liquid with a refractive index close to that of the sample. However, the Linnik imaging system is complex and difficult to adjust and is generally used in high-magnification systems with high costs. The Mirau type interference structure has only one microscope objective lens, which is widely used because of its strong anti-interference ability and compact structure. It is a feasible solution to transform water-immersion and oil-immersion objective lenses into interference objective lenses. However, the refractive index of water is generally 1.33, while the oil-immersion objective lenses are mainly glycerol (1.47) and cedar oil (1.51), and the refractive index of human skin is about 1.40. Therefore, in addition to introducing additional aberrations and chromatic aberrations, the use of water-immersion and oil-immersion objective lenses to transform into Mirau objective lenses cannot solve the problem of mismatch between the coherence plane and the focal plane.

[0006] To this end, the patent application number CN201510504729.7, entitled "Three-dimensional optical coherence tomography device and its application", uses a specially designed Mirau-type objective lens and an optical microscope module that allows OCT mode and orthogonal polarization spectral imaging (OPSI) mode. Among them, the design of the Mirau-type objective lens is through an Olympus water immersion objective lens design, replacing the first immersion medium and the second immersion medium with silicone oil, the thickness of the reflector and the beam splitter is 150 microns, and the thickness of the cover glass is the same as the thickness of the two glass plates; and the immersion Mirau objective lens designed using an Olympus objective lens (LUMPLFLN20×W, NA: 0.5) also ensures that the refractive index of the first immersion medium and the second immersion medium is the same, and can ensure the coincidence of the focal plane and the coherence plane when used for human skin tissue detection. However, it was found in actual tests that the patented product cannot guarantee good imaging quality. In particular, the invention utilizes a water immersion objective lens. When the immersion medium is replaced with silicone oil and three glass plates are added, large chromatic aberration and spherical aberration are introduced, which seriously affects the imaging quality and causes certain errors in human skin detection.

[0007] How to ensure the overlap of the focal plane and the coherence plane while ensuring good imaging quality to ensure the accuracy of human skin detection is a problem that this field has always wanted to solve. Summary of the invention

[0008] In view of the above problems, the object of the present invention is to solve part of the problems in the prior art, or at least alleviate these problems.

[0009] A 10x immersion Mirau interference microscope objective lens comprises a cover glass, a first immersion medium, a beam splitter, a second immersion medium, a reflector and a lens group for correcting aberrations, which are arranged in sequence along an optical axis from an object side to an image side; the lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, which are arranged in sequence along the optical axis; the cover glass, the beam splitter and the reflector are flat glass; the first lens and the second lens are spherical lenses, the third lens and the fourth lens are double-cemented lenses, the fifth lens and the sixth lens are double-cemented lenses, and the seventh lens is a spherical lens;

[0010] The illumination light path passes through the seventh lens, the sixth lens, the fifth lens, the fourth lens, the third lens, the second lens, the first lens, the reflector and the second immersion medium in sequence and is divided into two beams of light; one beam of light is reflected by the beam splitter and the second immersion medium and then reaches the reflector surface and reflects again, and the other beam of light is transmitted through the beam splitter and passes through the first immersion medium and the cover glass and then reaches the sample surface, the scattered light on the sample surface and the reflected light on the reflector surface interfere, and the surface information of the sample is reconstructed according to the interference fringes;

[0011] The first immersion medium and the second immersion medium are media having the same or similar refractive index as that of the sample.

[0012] Furthermore, the cover glass, the beam splitter and the reflector have an aperture of 15 mm, a center thickness of 0.5 mm, and the glass material used is fused quartz; the first lens has an aperture of 16 mm, a center thickness of 3.024 mm, and both left and right surfaces are spherical, the left spherical surface has a curvature radius of -20.172 mm, and the right spherical surface has a curvature radius of -15.594 mm, and the glass material used is N-LAK34; the second lens has an aperture of 17 mm, a center thickness of 4.02 The diameter of the third lens is 19 mm, the center thickness is 2.377 mm, the left and right surfaces are both spherical, the radius of curvature of the left spherical surface is -28.282 mm, the radius of curvature of the right spherical surface is 18.525 mm, and the glass material used is H-ZF71; the diameter of the fourth lens is 19 mm The center thickness is 19 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is 18.525 mm, the right spherical surface curvature radius is -39.887 mm, and the glass material used is H-LAK53B; the diameter of the fifth lens is 19 mm, the center thickness is 3.883 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is 34.23 mm, the right spherical surface curvature radius is 22.287 mm, and the glass material used is H-QF3; the sixth lens The diameter of the lens is 19 mm, the center thickness is 3.82 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is 22.287 mm, the right spherical surface curvature radius is 25471 mm, and the glass material used is N-SF6HT; the diameter of the seventh lens is 16 mm, the center thickness is 1.82 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is 40.401 mm, the right spherical surface curvature radius is 16.858 mm, and the glass material used is N-SK16;

[0013] The filling medium thickness of the first immersion medium and the second immersion medium is 10 mm; the air gap between the reflector and the first lens is 2.6 mm, the air gap between the first lens and the second lens is 1.33 mm, the gap between the second lens and the third lens is 1.33 mm, the gap between the fourth lens and the fifth lens is 0.5 mm, and the gap between the sixth lens and the seventh lens is 9 mm.

[0014] The first immersion medium is filled in the beam splitter and the cover glass; the second immersion medium is filled in the reflector and the beam splitter.

[0015] Preferably, the first immersion medium and the second immersion medium are silicone oil, and the refractive index thereof is 1.403.

[0016] Furthermore, the cover glass is coated with an anti-reflection film, and the transmittance and reflectance ratios are 99.5%:0.5%.

[0017] Furthermore, the beam splitter is coated with a beam splitter film, and the transmittance and reflectance ratios are 80%:20%.

[0018] Furthermore, there is a circular spot coated with a reflective film at the center of the reflector, and the transmittance and reflectance ratios are 5%:95%.

[0019] The cover glass, beam splitter and reflector are all circular optical glass plates.

[0020] The microscope objective has a numerical aperture of 0.3, a focal length of 20 mm, a parfocal distance of 60 mm, a working distance of 10 mm, and an object field of view of 0.68 mm.

[0021] The present invention has the following beneficial effects:

[0022] 1. The 10x immersion Mirau interference microscope objective optical system of the present invention operates in the near-infrared band (820nm-870nm), has a numerical aperture of 0.3, a focal length of 20 mm, a parfocal distance of 60 mm, a working distance of 10 mm, an object field of view of 0.68 mm, a filling medium refractive index of 1.403, a first medium of silicone oil, and a second medium of silicone oil, which can well correct the chromatic aberration and spherical aberration introduced by silicone oil and glass plate, and reduce the mismatch between the interference plane and the focal plane, greatly improve the imaging quality, and the imaging quality is excellent, and the imaging quality is close to the diffraction limit;

[0023] 2. The structure of the present invention is simple and compact, insensitive to environmental interference, uses fewer optical elements, has low cost, is suitable for low-coherence interference, and can be well used for three-dimensional detection of the human skin surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a 10x immersion Mirau interference microscope objective optical system of the present invention.

[0025] Figure 2 It is a schematic diagram of the optical path of the 10x immersion Mirau interference microscope objective optical system of the present invention.

[0026] Figure 3 It is a transfer function diagram of the 10x immersion Mirau interference microscope objective optical system of the present invention.

[0027] Figure 4 It is a point arrangement diagram of the 10-fold immersion Mirau interference microscope objective optical system of the present invention.

[0028] Figure 5 It is a field curvature / distortion diagram of the 10x immersion Mirau interference microscope objective optical system of the present invention.

[0029] Figure 6 It is a light aberration diagram of the 10x immersion Mirau interference microscope objective optical system of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings. The embodiments of the present invention are only used to illustrate the present invention rather than to limit the present invention. Without departing from the technical idea of ​​the present invention, various substitutions and changes can be made according to common technical knowledge and customary means in the field, which should all be included in the scope of the present invention.

[0031] In order to solve the above problems, the present invention designs a 10-fold immersion Mirau interference objective lens.

[0032] like Figure 1 As shown, a 10x immersion Mirau interference microscope objective lens comprises a cover glass 1, a first immersion medium 101, a beam splitter 2, a second immersion medium 102, a reflector 3 and a lens group for correcting aberrations, which are arranged in sequence along the optical axis from the object side to the image side; the lens group comprises a first lens 4, a second lens 5, a third lens 6, a fourth lens 7, a fifth lens 8, a sixth lens 9 and a seventh lens 10, which are arranged in sequence along the optical axis; the cover glass 1, the beam splitter 2 and the reflector 3 are flat glass; the first lens 4 and the second lens 5 are spherical lenses, the third lens 6 and the fourth lens 7 are double-cemented lenses, the fifth lens 8 and the sixth lens 9 are double-cemented lenses, and the seventh lens 10 is a spherical lens;

[0033] like Figure 2 As shown, the illumination light path passes through the seventh lens 10, the sixth lens 9, the fifth lens 8, the fourth lens 7, the third lens 6, the second lens 5, the first lens 4, the reflector 3 and the second immersion medium 102 in sequence and is divided into two beams of light; one beam of light is reflected by the beam splitter 2 and the second immersion medium 102 and then reaches the surface of the reflector 3 and reflects again, and the other beam of light is transmitted through the beam splitter 2 and passes through the first immersion medium 101 and the cover glass 1 and then reaches the sample surface, and the scattered light on the sample surface and the reflected light on the surface of the reflector 3 interfere with each other, and the surface information of the sample is reconstructed according to the interference fringes;

[0034] The first immersion medium 101 and the second immersion medium 102 are media having the same or similar refractive index as the sample.

[0035] The sample here mainly refers to the human skin to be tested. The first immersion medium 101 and the second immersion medium 102 are silicone oil, whose refractive index is 1.403, which can well match the refractive index of human skin in the near infrared band, so that the focal plane of the interference objective lens and the interference plane intersect during measurement.

[0036] The first immersion medium 101 may be filled in the beam splitter 2 and the cover glass 1 ; the second immersion medium 102 may be filled in the reflector 3 and the beam splitter.

[0037] The present invention uses a first immersion medium and a second immersion medium with the same or similar refractive index as human skin to ensure the coincidence of the interference plane and the focal plane. In addition, the lens group at the rear end can correct the aberration introduced by silicone oil and glass plate, effectively reducing spherical aberration and chromatic aberration, greatly improving the imaging quality, and making the detection more accurate.

[0038] Combined with Table 1, the diameters of the cover glass 1, the beam splitter 2 and the reflector 3 are all 15 mm, the center thickness is 0.5 mm, and the glass material used is fused quartz; the diameter of the first lens 4 is 16 mm, the center thickness is 3.024 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is -20.172 mm, the right spherical surface curvature radius is -15.594 mm, and the glass material used is N-LAK34; the diameter of the second lens 5 is 17 mm, the center thickness is 4. 02 mm, both left and right surfaces are spherical, the left spherical surface curvature radius is 91.753 mm, the right spherical surface curvature radius is -32.323 mm, and the glass material used is H-LAK1; the third lens 6 has a diameter of 19 mm, a center thickness of 2.377 mm, both left and right surfaces are spherical, the left spherical surface curvature radius is -28.282 mm, the right spherical surface curvature radius is 18.525 mm, and the glass material used is H-ZF71; the fourth lens 7 has a diameter of 19 mm, a center thickness of 2.377 mm, both left and right surfaces are spherical, the left spherical surface curvature radius is -28.282 mm, the right spherical surface curvature radius is 18.525 mm, and the glass material used is H-ZF71; The diameter of the fifth lens 8 is 19 mm, the center thickness is 3.883 mm, the left and right surfaces are both spherical, the radius of curvature of the left spherical surface is 34.23 mm, the radius of curvature of the right spherical surface is 22.287 mm, and the glass material used is H-QF3; the sixth lens 9 has a diameter of 19 mm, a center thickness of 3.883 mm, and the left and right surfaces are both spherical, the radius of curvature of the left spherical surface is 34.23 mm, and the radius of curvature of the right spherical surface is 22.287 mm, and the glass material used is H-QF3; The diameter of the seventh lens 10 is 16 mm, the center thickness is 1.82 mm, the left and right surfaces are both spherical, the left spherical radius of curvature is 22.287 mm, the right spherical radius of curvature is 25471 mm, and the glass material used is N-SF6HT; the diameter of the seventh lens 10 is 16 mm, the center thickness is 1.82 mm, the left and right surfaces are both spherical, the left spherical radius of curvature is 40.401 mm, the right spherical radius of curvature is 16.858 mm, and the glass material used is N-SK16;

[0039] The filling medium thickness of the first immersion medium 101 and the second immersion medium 102 are both 10 mm; the air gap between the reflector 3 and the first lens 4 is 2.6 mm, the air gap between the first lens 4 and the second lens 5 is 1.33 mm, the gap between the second lens 5 and the third lens 6 is 1.33 mm, the gap between the fourth lens 7 and the fifth lens 8 is 0.5 mm, and the gap between the sixth lens 9 and the seventh lens 10 is 9 mm.

[0040]

[0041]

[0042] Table 1

[0043] Correspondingly, the numerical aperture of the microscope objective is 0.3, the focal length is 20 mm, the parfocal distance is 60 mm, the working distance is 10 mm, the object field of view is 0.68 mm, the refractive index of the filling medium is 1.403, the first medium is silicone oil, and the second medium is silicone oil. The structure with the above specific values ​​can reduce the mismatch between the interference plane and the focal plane, and can also solve the problem of dispersion mismatch between the two interference arms, ensuring the accuracy of human skin detection.

[0044] The cover glass 1, the beam splitter 2 and the reflector 3 can be a circular optical glass plate.

[0045] The cover glass 1 is coated with an anti-reflection film, and the transmittance and reflectance ratios are 99.5%:0.5%.

[0046] The beam splitter 2 is coated with a beam splitter film, and the transmittance and reflectance ratios are 80%:20%, so that when used for skin tissue detection, the interference fringes have a good contrast.

[0047] The center of the reflector 3 has a circular spot coated with a reflective film, and the transmittance and reflectance ratios are 5%:95%.

[0048] The above coating method can effectively solve the defect that the reflected light is much greater than the scattered light, thereby coordinating with other improvements to further improve the imaging quality.

[0049] Working principle:

[0050] Parallel light incident illumination is required during operation. The near-infrared LED light source emits a wide spectrum light source, which is collimated and expanded by a collimating lens, incident on a beam splitter prism, and after passing through a Mirau interference objective lens, one beam of light is focused on the reflector 3 for emission, and the other beam of light enters the sample for scattering. The light reflected by the reflector 3 interferes with the scattered light on the sample surface, and after being focused by the tube lens, the camera collects the interference fringes, which are then used for three-dimensional detection of the human skin surface.

[0051] Figure 3 This is the modulation transfer function diagram of the 10x immersion Mirau interference microscope objective lens of the present invention. As can be seen from the figure, the modulation transfer function is close to the diffraction limit at 0 field of view, 0.707 field of view and full field of view, and has high resolution. For the interference system, four pixels are used to resolve one period of interference fringes. The single pixel size of the CMOS camera used in the present invention is 8um, and the maximum spatial frequency is calculated to be 31.25lp / mm. When the spatial frequency is 35lp / mm, it is around 0.4. In general, it is believed that MTF>0.3 imaging is relatively perfect, so the objective lens can perform good imaging.

[0052] Figure 4This is a spot diagram of the 10x immersion Mirau interference microscope objective lens of the present invention. It can be seen from the figure that the RMS spot radius is smaller than the Airy disk radius, and the imaging quality is better than the diffraction limit in the full field of view.

[0053] Figure 5 This is a field curvature / distortion diagram of the 10x immersion Mirau interference microscope objective optical system of the present invention. Since the CMOS camera collects interference fringes, the detector cannot automatically focus to the optimal imaging position like the human eye, so it is required that the image is clearly visible in the entire field of view. It can be seen from the figure that the maximum distortion is less than 0.1%, the maximum field curvature is within ±0.5 mm, and the field curvature and distortion are well corrected to meet the requirement that the imaging surface is flat.

[0054] Figure 6 This is a light aberration diagram of the 10x immersion Mirau interference microscope objective lens of the present invention. It can be found from the figure that the maximum value of the ordinate in the figure is within ±100 microns, the wavelength is within the range of 820nm-870nm, the shapes of the various colors of light are similar, and the spherical aberration and chromatic aberration are well corrected.

[0055] The 10x immersion Mirau interference microscope objective lens of the present invention works in the near-infrared band (820nm-870nm), has a numerical aperture of 0.3, a focal length of 20 mm, a parfocal distance of 60 mm, a working distance of 10 mm, an object field of view of 0.68 mm, a filling medium refractive index of 1.403, a first medium of silicone oil, and a second medium of silicone oil, and corrects various aberrations of silicone oil and a glass plate, reduces the mismatch between a focal plane and a coherent plane, improves imaging quality, and the imaging quality is close to the diffraction limit.

[0056] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0057] The above embodiments should be understood to be only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the contents of the present invention, technicians can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A 10x immersion Mirau interference microscope objective lens, characterized in that: The invention comprises a cover glass (1), a first immersion medium (101), a beam splitter (2), a second immersion medium (102), a reflector (3) and a lens group for correcting aberrations, which are arranged in sequence along the optical axis from the object side to the image side; the lens group comprises a first lens (4), a second lens (5), a third lens (6), a fourth lens (7), a fifth lens (8), a sixth lens (9) and a seventh lens (10) which are arranged in sequence along the optical axis; the cover glass (1), the beam splitter (2) and the reflector (3) are flat glass; the first lens (4) and the second lens (5) are spherical lenses, the third lens (6) and the fourth lens (7) are doublet lenses, the fifth lens (8) and the sixth lens (9) are doublet lenses, and the seventh lens (10) is a spherical lens; The illumination light path passes through the seventh lens (10), the sixth lens (9), the fifth lens (8), the fourth lens (7), the third lens (6), the second lens (5), the first lens (4), the reflector (3) and the second immersion medium (102) in sequence and is then divided into two beams of light; one beam of light is reflected by the beam splitter (2) and the second immersion medium (102) and then reaches the surface of the reflector (3) and is reflected again; the other beam of light is transmitted through the beam splitter (2) and passes through the first immersion medium (101) and the cover glass (1) and then reaches the surface of the sample; the scattered light on the surface of the sample and the reflected light on the surface of the reflector (3) interfere with each other, and surface information of the sample is reconstructed based on the interference fringes; The first immersion medium (101) and the second immersion medium (102) are media having a refractive index that is the same as or close to that of the sample.

2. The 10x immersion Mirau interference microscope objective lens according to claim 1, characterized in that: The cover glass (1), the beam splitter (2) and the reflector (3) all have a diameter of 15 mm, a center thickness of 0.5 mm, and the glass material used is fused quartz; the first lens (4) has a diameter of 16 mm, a center thickness of 3.024 mm, and both left and right surfaces are spherical surfaces, the left spherical surface has a curvature radius of -20.172 mm, and the right spherical surface has a curvature radius of -15.594 mm, and the glass material used is N-LAK34; the second lens (5) has a diameter of 17 mm, a center thickness of The diameter of the third lens (6) is 19 mm, the center thickness is 2.377 mm, the left and right surfaces are both spherical, the radius of curvature of the left spherical surface is -28.282 mm, the radius of curvature of the right spherical surface is 18.525 mm, and the glass material used is H-ZF71; the diameter of the fourth lens (7) is 19 mm, the center thickness is 2.377 mm, the left and right surfaces are both spherical, the radius of curvature of the left spherical surface is -28.282 mm, and the radius of curvature of the right spherical surface is 18.525 mm, and the glass material used is H-ZF71; the diameter of the fourth lens (7) is 1 9 mm, the center thickness is 19 mm, the left and right surfaces are both spherical, the left spherical radius of curvature is 18.525 mm, the right spherical radius of curvature is -39.887 mm, and the glass material used is H-LAK53B; the fifth lens (8) has an aperture of 19 mm, a center thickness of 3.883 mm, the left and right surfaces are both spherical, the left spherical radius of curvature is 34.23 mm, the right spherical radius of curvature is 22.287 mm, and the glass material used is H-QF3; the sixth lens ( The diameter of the seventh lens (9) is 19 mm, the center thickness is 3.82 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is 22.287 mm, the right spherical surface curvature radius is 25471 mm, and the glass material used is N-SF6HT; the diameter of the seventh lens (10) is 16 mm, the center thickness is 1.82 mm, the left and right surfaces are both spherical, the left spherical surface curvature radius is 40.401 mm, the right spherical surface curvature radius is 16.858 mm, and the glass material used is N-SK16; The filling medium thickness of the first immersion medium (101) and the second immersion medium (102) is 10 mm; the air gap between the reflector (3) and the first lens (4) is 2.6 mm, the air gap between the first lens (4) and the second lens (5) is 1.33 mm, the gap between the second lens (5) and the third lens (6) is 1.33 mm, the gap between the fourth lens (7) and the fifth lens (8) is 0.5 mm, and the gap between the sixth lens (9) and the seventh lens (10) is 9 mm.

3. The 10x immersion Mirau interference microscope objective lens according to claim 2, characterized in that: The first immersion medium (101) is filled in the beam splitter (2) and the cover glass (1); and the second immersion medium (102) is filled in the reflector (3) and the beam splitter.

4. The 10x immersion Mirau interference microscope objective lens according to claim 2 or 3, characterized in that: The first immersion medium (101) and the second immersion medium (102) are silicone oil, and the refractive index thereof is 1.

403.

5. The 10x immersion Mirau interference microscope objective lens according to claim 2, characterized in that: The cover glass (1) is coated with an anti-reflection film, and the transmittance and reflectance ratios are 99.5%:0.5%.

6. The 10x immersion Mirau interference microscope objective lens according to claim 2, characterized in that: The beam splitter (2) is coated with a beam splitting film, and the transmittance and reflectance ratios are 80%:20%.

7. The 10x immersion Mirau interference microscope objective lens according to claim 2, characterized in that: The center of the reflector (3) is provided with a circular spot coated with a reflective film, and the transmittance and reflectance ratios are 5%:95%.

8. The 10x immersion Mirau interference microscope objective lens according to claim 1, characterized in that: The cover glass (1), beam splitter (2) and reflector (3) are all circular optical glass plates.

9. The 10x immersion Mirau interference microscope objective lens according to claim 1, characterized in that: The microscope objective has a numerical aperture of 0.3, a focal length of 20 mm, a parfocal distance of 60 mm, a working distance of 10 mm, and an object field of view of 0.68 mm.

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