Large-view-field large-numerical-aperture ultraviolet broadband microscopic optical system

Abstract

The invention provides an ultraviolet broadband microscopic optical system with a large field of view and a large numerical aperture, and relates to the technical field of optical microscopes, the system comprises a microscope objective which is of a coaxial refraction and reflection structure and is formed by arranging a microscope objective front group, a microscope objective middle group and a microscope objective rear group in sequence; the relay system is used for receiving the emergent light of the microscope objective, forming parallel light beams and relaying the virtual exit pupil as a real exit pupil; the imaging tube lens is used for receiving the light rays emitted by the relay system and imaging the light rays to a detector; the working wave band of the microscopic optical system ranges from 250 nm to 500 nm, the amplification factor ranges from 25 times to 100 times, the numerical aperture NA is larger than or equal to 0.9, and the field of view is larger than or equal to 1 mm. In addition, the field of view of the system can be enlarged to over 2mm through the amplification optical system. The system can be used in the fields of semiconductor wafer detection, gene sequencing, life science, industrial detection and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of optical microscopes, and particularly to a large-field and large-numerical-aperture ultraviolet wide-band microscopic optical system. Background Art

[0002] Microscopes play an important role in the fields of natural science research and industrial production, and are widely used in semiconductor manufacturing, biomedicine, industrial quality inspection, environmental science and other aspects. According to the Dawes criterion, the microscope resolution formula is λ / (2NA) (λ represents the wavelength, and NA represents the numerical aperture of the objective lens). As the requirements for microscope resolution in various fields continue to climb, the detection light source wavelength shortens from visible light to ultraviolet light. Although this improves the resolution, it also significantly increases the difficulty of chromatic aberration correction. At the same time, increasing the numerical aperture can also improve the resolution of the objective lens, but this increases the difficulty of correcting the spherical aberration of the optical system. Currently, it is difficult for microscopes to simultaneously have large-field and high-resolution performance. For example, low-magnification objective lenses (less than 20X) have a large field of view. For example, the field of view of the Olympus PLN4X objective lens can reach 5 mm, but the numerical aperture is small (NA = 0.1) and the resolution is low; high-magnification objective lenses (greater than 50X) have a small field of view. For example, the field of view of the Olympus MXPLFLN50XBD objective lens is less than 0.6 mm, but the numerical aperture is large (NA = 0.8) and the resolution is high. Microscopic optical systems with large numerical apertures and large fields of view are extremely difficult to design and develop due to the large Lagrange invariant, and general commercial objective lenses are difficult to have such performance. However, such optical systems can significantly improve the detection efficiency while obtaining high-resolution microscopic images, and are urgently needed in many application fields.

[0003] Against the background of the rapid development of the national semiconductor chips, gene sequencing, life science and other fields, the demand for microscopic optical systems has increased significantly, and technical requirements of high numerical aperture, large field of view and wide spectral band have been put forward. As the core component of the microscopic optical system, the objective lens directly affects the overall imaging performance. At present, the imaging spectral range of the objective lens is gradually expanding from visible light to the deep ultraviolet (DUV) spectral band, and the numerical aperture is also increasing continuously. However, due to the limitations of ultraviolet band materials, it has become increasingly difficult to design a wide-band high-NA large-field microscope.

[0004] Existing microscopic optical systems are difficult to balance high resolution, large field of view, and wide-band performance. Especially in the ultraviolet band, due to material limitations, refractive ultraviolet microscopic systems have a small numerical aperture under the condition of chromatic aberration correction, making it difficult to achieve high resolution and unable to meet the working requirements of ultraviolet detection. For ultraviolet light with a wavelength range starting from 250nm, the types of available optical materials are extremely limited, usually only fused silica and calcium fluoride. The dispersion characteristics of these two materials in the ultraviolet band are relatively similar, resulting in it being difficult for a single optical component (such as a long focal length tube lens or a microscopic objective lens) to achieve effective chromatic aberration correction. In particular, the achromatic design of the long focal length tube lens is extremely difficult. So far, there has been no relevant report on a high-resolution, large-field-of-view microscopic optical system that successfully uses only these two materials in the wavelength range from 250nm to the visible light band. Summary of the Invention

[0005] To this end, an embodiment of the present invention provides a large-field-of-view, large-numerical-aperture ultraviolet wide-band microscopic optical system, which is used to solve the problem that existing ultraviolet microscopic optical systems are difficult to simultaneously achieve high magnification, large numerical aperture, and large field of view in a wide band (especially the ultraviolet band starting from 250nm).

[0006] To solve the above problems, an embodiment of the present invention provides a large-field-of-view, large-numerical-aperture ultraviolet wide-band microscopic optical system, which includes:

[0007] A microscopic objective lens, adopting a coaxial catadioptric structure, which is sequentially composed of a front group of the microscopic objective lens, a middle group of the microscopic objective lens, and a rear group of the microscopic objective lens;

[0008] A relay system, used to receive the light rays emitted by the microscopic objective lens and form parallel light beams, and relay the virtual exit pupil to a real exit pupil;

[0009] An imaging tube lens, used to receive the light rays emitted by the relay system and image them onto a detector;

[0010] Among them, the working band of the microscopic optical system is from 250nm to 500nm, the magnification is in the range of 25 times to 100 times, the numerical aperture NA is greater than or equal to 0.9, and the field of view is greater than or equal to 1mm.

[0011] Preferably, the front group of the microscopic objective lens is composed of 3 to 6 lenses, which is used to reduce the incident angle of light rays and correct field curvature and lateral chromatic aberration. The front group of the microscopic objective lens at least includes one negative lens, and the focal length of the front group of the microscopic objective lens satisfies: 40 < |f front / f micro | < 250, where f micro is the focal length of the microscopic objective lens, and f front is the focal length of the front group of the microscopic objective lens.

[0012] Preferably, the middle group of the microscopic objective lens consists of 3 to 7 lenses, bears the main optical power of the microscopic objective lens, and corrects the secondary spectrum and field curvature. The focal length of the middle group of the microscopic objective lens satisfies: 1.5 < f middle / f micro <4, where f micro is the focal length of the microscopic objective lens, and f middle is the focal length of the middle group of the microscopic objective lens.

[0013] Preferably, the rear group of the microscopic objective lens consists of 2 to 4 lenses. Among them, if there are 3 lenses, the rear group of the microscopic objective lens includes a concave mirror, a thick meniscus lens, and a Mangin mirror; if there are 2 lenses, the rear group of the microscopic objective lens includes a thick meniscus lens and a Mangin mirror. The focal length of the rear group of the microscopic objective lens satisfies: 2 < f back / f micro <7, where f micro is the focal length of the microscopic objective lens, and f back is the focal length of the rear group of the microscopic objective lens.

[0014] Preferably, the curvature ρ of the rear surface of the Mangin mirror satisfies: ρ > -1 / 500 mm -1 , and the coated area of its reflecting surface is located outside the central optical aperture, which is used to correct the axial chromatic aberration and reduce the aperture of the concave mirror.

[0015] Preferably, the magnification β of the rear group of the microscopic objective lens satisfies: 1.3 < β < 2, and the curvature directions of the thick meniscus lens and the concave mirror are the same, which is used to eliminate the axial chromatic aberration.

[0016] Preferably, the concave mirror is provided with a central optical aperture, and its focal length satisfies: 0.5 < f mirror / f back <1.5, where f mirror is the focal length of the concave mirror.

[0017] Preferably, the relay system consists of 4 to 10 lenses, which is divided into the front group of the relay system and the rear group of the relay system. The absolute value of its focal length f a satisfies: |f a | ≥ 1000, and the ratio of the focal length f ar of the front group of the relay system to the focal length f af of the rear group of the relay system satisfies: 0.25 < f ar / f af < 4.

[0018] Preferably, the imaging tube lens consists of 2 to 10 lenses, and its focal length satisfies:

[0019]

[0020] where f adis the focal length of the imaging tube lens, f af is the focal length of the front group of the relay system, f ar is the focal length of the rear group of the relay system, f micro is the focal length of the microscopic objective lens.

[0021] Preferably, all optical elements of the microscopic objective lens, the relay system and the imaging tube lens are made of only two materials, fused silica and calcium fluoride, and chromatic aberration correction in the wavelength range of 250 nm to 500 nm is achieved through combined achromatic design.

[0022] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0023] (1) Compared with the existing commercial microscopic systems, the optical system of the present invention has a wider working wavelength range, covering the ultraviolet wavelength range of 250 nm - 500 nm, which can meet the wide-band ultraviolet imaging requirements; it has a higher numerical aperture, a larger field of view, a magnification between 20 - 100 times, a numerical aperture exceeding 0.9, a field of view exceeding 1 mm, and with the help of the magnifying optical system, the field of view can be expanded to more than 2 mm, greatly improving the imaging resolution and the observation range.

[0024] (3) The present invention uses only two materials, fused silica and calcium fluoride, and through a unique combined achromatic design of the tube lens and the objective lens, wide-band achromatic aberration is achieved. This not only breaks through the limitation of limited materials in the ultraviolet wavelength range, but also solves the problem of difficult achromatic aberration correction for a single optical part. While meeting the requirements of wide-band and high-resolution imaging, the types of materials used are reduced, and the cost and design complexity are lowered.

[0025] (3) The structural design of the present invention relatively relaxes the processing and assembly tolerances of the ultraviolet microscopic optical system, reducing the difficulty of system development. Through combined achromatic design to optimize the overall performance, while ensuring high resolution and large field of view, the dependence on the processing and assembly accuracy of the microscopic objective lens elements is reduced, improving production efficiency and product stability, and being more conducive to large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly describe the drawings required in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be construed as limiting the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0027] Figure 1 is a schematic structural diagram of a large-field-of-view and large-numerical-aperture ultraviolet wide-band microscopic optical system provided by the present invention;

[0028] Figure 2 Schematic diagram of the optical structure of the microscopic objective lens in the embodiment;

[0029] Figure 3 Schematic diagram of the optical structure of the relay system in the embodiment;

[0030] Figure 4 Schematic diagram of the optical structure of the imaging tube lens in the embodiment;

[0031] Figure 5 Schematic diagram of the axial chromatic aberration of Case 1 in the embodiment;

[0032] Figure 6 Schematic diagram of the axial chromatic aberration of Case 2 in the embodiment.

[0033] Reference numerals in the specification drawings: 11, first lens; 12, second lens; 13, third lens; 14, fourth lens; 15, fifth lens; 16, sixth lens; 17, seventh lens; 18, eighth lens; 19, ninth lens; 110, tenth lens; 111, concave mirror; 112, thick meniscus lens; 113, Mangin mirror; 114, object; 115, aperture; 21, eleventh lens; 22, twelfth lens; 23, thirteenth lens; 24, fourteenth lens; 25, fifteenth lens; 26, sixteenth lens; 27, seventeenth lens; 28, eighteenth lens; 29, real pupil; 31, nineteenth lens; 32, twentieth lens; 33, twenty - first lens; 34, twenty - second lens. Detailed implementation manners

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Embodiment 1

[0036] In the field of microscopic optics, it is quite difficult to achieve high resolution, large field of view and wide wavelength band simultaneously. Generally, ultraviolet light with a wavelength above 200 nm can be subdivided into three categories: UV - A, with a wavelength range of 320 nm to 400 nm; UV - B, with a wavelength between 280 nm and 320 nm; UV - C, with a wavelength of 200 nm to 280 nm. When the working wavelength band of the ultraviolet microscopic system covers at least one of the above - mentioned ultraviolet bands, it is called a wide - band ultraviolet microscopic system.

[0037] However, limited by the material properties in the ultraviolet band, the existing refractive ultraviolet microscopy systems have obvious shortcomings. In the case of eliminating chromatic aberration, the numerical aperture of such systems is often small, which makes it difficult to achieve high resolution and simply cannot meet the actual working requirements of ultraviolet detection.

[0038] To address these intractable problems, the present invention has developed an innovative approach: adopting a design scheme of combining a tube lens and an objective lens to correct chromatic aberration, thus breaking through the limitation of relying solely on a single optical component for chromatic aberration correction. In this way, the system can accurately correct chromatic aberration for broadband ultraviolet light, and then perfectly balance the three working requirements of high resolution, large field of view, and broadband.

[0039] As Figure 1 shown, an embodiment of the present invention provides a large field of view and large numerical aperture ultraviolet broadband microscopic optical system, which includes:

[0040] A microscopic objective lens, adopting a coaxial catadioptric structure, is sequentially composed of a front group, a middle group, and a rear group of the microscopic objective lens;

[0041] A relay system, used to receive the light rays emitted by the microscopic objective lens and form parallel light beams, and relay the virtual exit pupil to a real exit pupil;

[0042] An imaging tube lens, used to receive the light rays emitted by the relay system and image them onto a detector;

[0043] Among them, the working wavelength band of the microscopic optical system is from 250 nm to 500 nm, the magnification is in the range of 25 times to 100 times, the numerical aperture NA is greater than or equal to 0.9, and the field of view is greater than or equal to 1 mm.

[0044] From the above technical solutions, the present invention provides a large field of view and large numerical aperture ultraviolet broadband microscopic optical system. The microscopic objective lens adopts a coaxial catadioptric structure and is sequentially composed of a front group, a middle group, and a rear group to preliminarily process the light rays. The relay system receives the light rays emitted by the microscopic objective lens, forms parallel light beams and relays the virtual exit pupil to a real exit pupil. The imaging tube lens receives the light rays emitted by the relay system and images them onto a detector. The system of the present invention can work in a wide ultraviolet wavelength band to meet the broadband imaging requirements in related fields. The design of high magnification, large numerical aperture, and large field of view can provide high-resolution imaging and improve the detection efficiency. Each component works together to achieve large field of view and large numerical aperture ultraviolet broadband microscopic imaging, and the structural design is reasonable, reducing the difficulty of system development.

[0045] In this embodiment, the microscopic objective lens adopts a coaxial catadioptric structure, which is sequentially composed of a front group of the microscopic objective lens (composed of 3 to 6 lenses and at least including one negative lens), a middle group of the microscopic objective lens (composed of 3 to 7 lenses), and a rear group of the microscopic objective lens (composed of 2 to 4 lenses). Among them, if the rear group of the microscopic objective lens is composed of 3 lenses, the rear group of the microscopic objective lens includes a concave mirror 111, a thick meniscus lens 112, and a Mangin mirror 113; if the rear group of the microscopic objective lens is composed of 2 lenses, the rear group of the microscopic objective lens includes a thick meniscus lens 112 and a Mangin mirror 113.

[0046] Further, the focal length of the front group of the microscopic objective lens satisfies: 40 < |f front / f micro | < 250; the focal length of the middle group of the microscopic objective lens satisfies: 1.5 < f middle / f micro < 4; the focal length of the rear group of the microscopic objective lens satisfies: 2 < f back / f micro < 7, where f micro is the focal length of the microscopic objective lens, f front is the focal length of the front group of the microscopic objective lens, f middle is the focal length of the middle group of the microscopic objective lens, f back is the focal length of the rear group of the microscopic objective lens.

[0047] As Figure 2 shown, a specific structure of the microscopic objective lens is given. Adopting a coaxial catadioptric design, along the optical axis direction, from the image side to the object side, it can be sequentially divided into a front group of the microscopic objective lens, a middle group of the microscopic objective lens, and a rear group of the microscopic objective lens, and all lens surfaces are spherical surfaces.

[0048] Front group of the microscopic objective lens: It is composed of a first lens 11 (positive lens), a second lens 12 (negative lens), a third lens 13 (positive lens), a fourth lens 14 (positive lens), and a fifth lens 15 (positive lens). This part is mainly used to reduce the light incident angle, correct the field curvature and lateral chromatic aberration of the system, and at the same time play a balancing role for coma, astigmatism, and spherical aberration.

[0049] Middle group of the microscopic objective lens: It includes a sixth lens 16 (positive lens), a seventh lens 17 (positive lens), an eighth lens 18 (positive lens), a ninth lens 19 (negative lens), and a tenth lens 110 (positive lens). The middle group of the microscopic objective lens undertakes most of the optical power and forms a primary image. Among them, the eighth lens 18, the ninth lens 19, and the tenth lens 110 are used to correct the secondary spectrum, and the ninth lens 19 also plays a role in correcting the field curvature.

[0050] Rear group of the microscope objective: It consists of a concave mirror 111, a thick meniscus lens 112 (negative lens), and a Mangin mirror 113. The concave mirror 111 is provided with a central circular opening, undertakes the main optical power of the rear group, and magnifies the numerical aperture twice. The magnification β satisfies 1.3 < β < 2, and its focal length satisfies: 0.5 < f mirror / f back <1.5, where f mirror is the focal length of the concave mirror. The thick meniscus lens 112 is not in direct contact with other components, and the curvature radius direction of its meniscus surface is the same as that of the concave mirror 111, mainly used to eliminate axial chromatic aberration. The rear surface of the Mangin mirror 113 is coated with a reflective film outside the central circular area, and the central circular area allows the object light to pass through and enter the system. The rear surface has a very small curvature, and the curvature range is ρ > -1 / 500mm -1 , which is used to correct chromatic aberration and spherical aberration and reduce the aperture of the concave mirror 111. The rear group of the microscope objective works in cooperation with the first two groups of the microscope objective to correct axial chromatic aberration and spherical aberration.

[0051] Furthermore, the working principle of the microscope objective is as follows: The light starts from the object (or specimen) 114, first passes through the central optical hole of the Mangin mirror 113, then passes through the thick meniscus lens 112, and then is reflected on the surface of the concave mirror 111. The reflected light reaches the reflective surface of the Mangin mirror 113, and then the light passes through the central optical hole of the concave mirror 111 again, and an intermediate image is formed between the concave mirror 111 and the tenth lens 110. After the intermediate image is formed, the light beam sequentially passes through the tenth lens 110, the ninth lens 19, the eighth lens 18, the seventh lens 17, the sixth lens 16, the aperture stop 115, the fifth lens 15, the fourth lens 14, the third lens 13, the second lens 12, the first lens 11, and finally, with the help of the relay system and the imaging tube lens, an image is formed on the detector.

[0052] In this embodiment, the relay system adopts a coaxial structure and is composed of 4 to 10 lenses, which are divided into the front group and the rear group of the relay system. It is used to receive the light emitted by the microscope objective and form a parallel light beam, and relay the virtual exit pupil to a real exit pupil. The absolute value of the focal length f of the relay system satisfies: |f a |≥1000, and the ratio of the focal length f of the front group of the relay system to the focal length f of the rear group of the relay system satisfies: 0.25 < f a |≥1000, and the ratio of the focal length f of the front group of the relay system to the focal length f of the rear group of the relay system satisfies: 0.25 < f ar of the front group of the relay system to the focal length f af of the rear group of the relay system satisfies: 0.25 < f ar / f af < 4.

[0053] Such as Figure 3As shown, a specific structure of the relay system is given. Adopting a coaxial design, the front group of the relay system consists of the eleventh lens 21, the twelfth lens 22, the thirteenth lens 23, and the fourteenth lens 24; the rear group of the relay system consists of the fifteenth lens 25, the sixteenth lens 26, the seventeenth lens 27, and the eighteenth lens 28.

[0054] The main function of this relay system is to receive the light rays emitted from the microscopic objective lens. After the light rays enter the relay system, they sequentially pass through the eighteenth lens 28, the seventeenth lens 27, the sixteenth lens 26, the fifteenth lens 25, the fourteenth lens 24, the thirteenth lens 23, the twelfth lens 22, and the eleventh lens 21, and finally form a parallel light beam, and transmit this light beam to the real pupil 29 outside the relay system.

[0055] In this embodiment, the imaging tube lens consists of 2 to 10 lenses, and is used to receive the light rays emitted from the relay system and image them onto the detector. The focal length of the imaging tube lens satisfies:

[0056]

[0057] where f ad is the focal length of the imaging tube lens, f af is the focal length of the front group of the relay system, f ar is the focal length of the rear group of the relay system, f micro is the focal length of the microscopic objective lens.

[0058] As Figure 4 shown, a specific structure of the imaging tube lens is given, and the nineteenth lens 31, the twentieth lens 32, the twenty - first lens 33, and the twenty - second lens 34 are arranged in sequence from left to right.

[0059] To sum up, under the conditions of a narrow wavelength band and a small field of view, the microscopic objective lens of the present invention has good imaging performance. When the microscopic objective lens is jointly optimized with the imaging tube lens and the relay system, the residual chromatic aberration and distortion existing in the microscopic objective lens can be corrected, thereby broadening the working wavelength band of the system, expanding the field of view range, and improving the imaging quality of the entire optical system. After optimization, this optical system can achieve a magnification of 25 to 100 times within the wavelength band of 250 nm to 500 nm, the numerical aperture (NA) can reach 0.9, and the field of view exceeds 1 mm. In addition, with the help of the magnifying optical system, the field of view of this system can be further increased to more than 2 mm.

[0060] It is worth mentioning that this microscopic optical system only uses two kinds of optical glasses, fused silica and calcium fluoride, as materials.

[0061] The following combines specific cases to illustrate the advantages of the present invention.

[0062] Case 1: Provide a large-field and large numerical aperture ultraviolet wide-band microscopic optical system. The microscopic optical system is mainly composed of a microscopic objective lens, a relay system, and an imaging tube lens, and can operate in the wavelength range of 250nm to 500nm. Its magnification is 50 times, NA reaches 0.9, and the field of view is 1mm.

[0063] Microscopic objective lens: The structure is as Figure 2 shown, and it is divided into the front group of the microscopic objective lens, the middle group of the microscopic objective lens, and the rear group of the microscopic objective lens. Among them, the optical element parameters of the front group and the middle group of the microscopic objective lens are shown in Table 1, and the optical element parameters of the rear group of the microscopic objective lens are shown in Table 2. The front group of the microscopic objective lens only has a weak optical power, and its focal length f front is: |f front / f micro | = 151.01; The middle group of the microscopic objective lens undertakes most of the optical power of the objective lens, and its focal length f middle is: f middle / f micro = 2.76; The rear group of the microscopic objective lens undertakes part of the optical power of the objective lens, and its focal length f back is: f back / f micro = 2.65; At the same time, it plays a role in magnifying the numerical aperture, and the magnification β = 1.44. In addition, the concave mirror 111 undertakes the main optical power of the rear group of the microscopic objective lens, and its focal length f mirror is: f mirror / f back = 1.04; The curvature ρ of the rear surface of the Mangin mirror 113 is -1 / 1346.80mm -1 .

[0064] Relay system: The structure is as Figure 3 shown, and it is composed of the front group of the relay system and the rear group of the relay system. Its optical element parameters are shown in Table 3. The ratio of the focal length f ar of the front group of the relay system to the focal length f af of the rear group of the relay system is: f ar / f af = 0.97, and the focal length f a of the relay system is -2059.39.

[0065] Imaging tube lens: The structure is as Figure 4 shown, and its optical element parameters are shown in Table 4. The focal length of the imaging tube lens is

[0066] Table 1 Optical element parameters of the front group and the middle group of the microscopic objective lens in Case 1

[0067]

[0068] Table 2 Optical element parameters of the rear group of the microscopic objective lens in Case 1

[0069]

[0070] Table 3 Optical element parameters of the relay system in Case 1

[0071]

[0072]

[0073] Table 4 Optical element parameters of the imaging tube lens in Case 1

[0074]

[0075] From Figure 5 it can be intuitively seen that the microscopic optical system has successfully achieved achromatism in the wavelength range of 250nm to 500nm, further demonstrating the superiority of its optical performance.

[0076] Case 2: Provide a wide-field and large numerical aperture ultraviolet wide-band microscopic optical system. The microscopic optical system mainly consists of a microscopic objective lens, a relay system, and an imaging tube lens, and can operate in the wavelength range of 250nm to 500nm. Its magnification is 65 times, NA reaches 0.9, and the field of view is 0.8mm.

[0077] Microscopic objective lens: The structure is as Figure 2 shown, and it is divided into the front group of the microscopic objective lens, the middle group of the microscopic objective lens, and the rear group of the microscopic objective lens. Among them, the optical element parameters of the front group and the middle group of the microscopic objective lens are shown in Table 5, and the optical element parameters of the rear group of the microscopic objective lens are shown in Table 6. The front group of the microscopic objective lens only has a weak optical power, and its focal length f front is: |f front / f micro | = 151.01; the middle group of the microscopic objective lens undertakes most of the optical power of the objective lens, and its focal length f middle is: f middle / f micro = 2.76; the rear group of the microscopic objective lens undertakes part of the optical power of the objective lens, and its focal length f back is: f back / f micro = 2.65; at the same time, it plays a role in magnifying the numerical aperture, and the magnification β = 1.44. In addition, the concave mirror 111 undertakes the main optical power of the rear group of the microscopic objective lens, and its focal length f mirror is: f mirror / f back = 1.04; the curvature ρ of the rear surface of the Mangin mirror 113 is ρ = -1 / 1346.80mm -1 .

[0078] Relay system: The structure is as Figure 3As shown, it is composed of the front group of the relay system and the rear group of the relay system, and its optical element parameters are shown in Table 7. The focal length f of the front group of the relay system ar and the focal length f of the rear group of the relay system af The ratio is: f ar / f af = 0.8, and the focal length f of the relay system a = -1104.25.

[0079] Imaging tube lens: The structure is as shown in Figure 4 shown, and its optical element parameters are shown in Table 8. The focal length of the imaging tube lens is

[0080] Table 5 Optical element parameters of the front group and the middle group of the microscope objective in Case 2

[0081]

[0082] Table 6 Optical element parameters of the rear group of the microscope objective in Case 2

[0083]

[0084] Table 7 Optical element parameters of the relay system in Case 2

[0085]

[0086]

[0087] Table 8 Optical element parameters of the imaging tube lens in Case 2

[0088]

[0089] From Figure 6 it can be intuitively seen that the microscope optical system has successfully achieved achromatism in the wavelength range of 250 nm to 500 nm, further demonstrating the superiority of its optical performance.

[0090] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A wide-band ultraviolet microscope optical system with a large field of view and a large numerical aperture, characterized in that: include: The microscope objective lens adopts a coaxial catadioptric structure, and is composed of a front microscope objective lens group, a middle microscope objective lens group, and a rear microscope objective lens group arranged in sequence; A relay system, used to receive the light emitted by the microscope objective lens and form a parallel light beam, and relay the virtual exit pupil to a real exit pupil; An imaging tube lens, used to receive the light emitted by the relay system and image it onto a detector; The working wavelength band of the microscope optical system is 250nm to 500nm, the magnification is in the range of 25 times to 100 times, the numerical aperture NA is greater than or equal to 0.9, and the field of view is greater than or equal to 1mm.

2. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 1, characterized in that: The front group of the microscope objective lens is composed of 3 to 6 lenses, which are used to reduce the incident angle of light and correct field curvature and lateral chromatic aberration. The front group of the microscope objective lens includes at least one negative lens, and the focal length of the front group of the microscope objective lens satisfies: 40<|f front / f micro |<250, where f micro is the focal length of the microscope objective, f front is the focal length of the front group of the microscope objective.

3. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 1, characterized in that: The middle group of the microscope objective lens is composed of 3 to 7 lenses, which bear the main optical power of the microscope objective lens and correct the secondary spectrum and field curvature. The focal length of the middle group of the microscope objective lens satisfies: 1.5<f middle / f micro <4, where f micro is the focal length of the microscope objective, f middle is the focal length of the microscope objective group.

4. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 1, characterized in that: The rear group of the microscope objective lens is composed of 2 to 4 lenses, wherein if there are 3 lenses, the rear group of the microscope objective lens includes a concave reflector, a thick meniscus lens and a Mankin mirror; if there are 2 lenses, the rear group of the microscope objective lens includes a thick meniscus lens and a Mankin mirror; the focal length of the rear group of the microscope objective lens satisfies: 2<f back / f micro <7, where f micro is the focal length of the microscope objective, f back is the focal length of the rear group of the microscope objective.

5. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 4, characterized in that: The rear surface curvature ρ of the Mankin mirror satisfies: ρ>-1 / 500mm -1 , whose reflective surface coating area is located outside the central optical hole, is used to correct axial chromatic aberration and reduce the aperture of the concave reflector.

6. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 4, characterized in that: The magnification β of the rear group of the microscope objective lens satisfies: 1.3<β<2, and the curvature direction of the thick meniscus lens is consistent with that of the concave reflector, so as to eliminate axial chromatic aberration.

7. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 4, characterized in that: The concave reflector is provided with a central optical hole, and its focal length satisfies: 0.5< f mirror / f back <1.5, where f mirror is the focal length of the concave reflector.

8. The large-viewing-field, large-numerical-aperture, ultraviolet-wide-band microscope optical system according to claim 1, characterized in that: The relay system is composed of 4 to 10 lenses, which are divided into a front group of the relay system and a rear group of the relay system. a The absolute value satisfies: |f a |≥1000, and the focal length f of the front group of the relay system ar The focal length f of the rear group of the relay system af The ratio meets: 0.25 <f ar / f af <4.

9. The ultraviolet broadband microscope optical system with large viewing field and large numerical aperture according to claim 1, characterized in that: The imaging tube lens is composed of 2 to 10 lenses, and its focal length satisfies: where f ad is the focal length of the imaging tube lens, f af is the focal length of the front group of the relay system, f ar is the focal length of the rear group of the relay system, f micro is the focal length of the microscope objective.

10. The ultraviolet broadband microscope optical system with large viewing field and large numerical aperture according to claim 1, characterized in that: All optical elements of the microscope objective lens, relay system and imaging tube lens are made of only two materials: fused quartz and calcium fluoride, and chromatic aberration correction in the 250nm to 500nm band is achieved through a combined achromatic design.

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