A visible-ultraviolet dual-wavelength microscope objective lens and optical system

Abstract

The present invention relates to the technical field of optical instruments and discloses a visible-ultraviolet dual-wavelength microscope objective lens and an optical system. The optical system comprises a first lens group with positive optical power and a second lens group with negative optical power, which are arranged in sequence along the optical axis of the microscope objective lens from the object plane to the image plane. The second lens group comprises a front lens group with negative optical power, a middle lens group with positive optical power, and a rear lens group with positive optical power. The microscope objective lens also comprises an aperture stop, which is located between two adjacent lenses in the middle lens group. The microscope objective lens of the present invention effectively reduces the influence of chromatic aberration under a wide-spectrum light source by rationally matching positive and negative optical powers, maintains a high numerical aperture and a large field of view, and is capable of adapting to wide-spectrum ultraviolet laser wavelengths.

Description

Technical Field

[0001] The present invention relates to the technical field of optical instruments, and in particular to a visible-ultraviolet dual-wavelength microscope objective lens and an optical system. Background Art

[0002] Ultraviolet lasers have demonstrated significant advantages in target detection and identification, driving the rapid development of ultraviolet optical technology. With the increasing demand for detection accuracy in defense engineering, industrial inspection, space science, and other fields, microscope systems are gradually expanding into the ultraviolet band to improve resolution and contrast. The resolution of diffraction-limited features gradually improves with decreasing wavelength and increasing numerical aperture (NA), enabling the ultraviolet band to achieve resolution that surpasses that of visible light systems. At the same time, to meet the time requirements for full-surface wafer scanning and improve the throughput efficiency of automated optical inspection equipment, microscope objectives need to have ultraviolet operating bands, high numerical apertures, and large fields of view.

[0003] However, the deep ultraviolet high-resolution (large numerical aperture) microscope lenses currently on the market are mainly designed to be optimized for a single wavelength under narrow linewidth (pm level) conditions, which makes them insufficiently adaptable to the typical wider spectrum of ultraviolet laser wavelengths. Summary of the Invention

[0004] The present invention aims to improve at least one technical problem in the background technology.

[0005] A first aspect of the present invention provides a visible-ultraviolet dual-wavelength microscope objective lens, comprising a first lens group with positive optical power and a second lens group with negative optical power, which are sequentially arranged along the optical axis of the microscope objective lens from the object plane to the image plane;

[0006] The second lens group includes a front lens group having negative optical power, a middle lens group having positive optical power, and a rear lens group having positive optical power;

[0007] The microscope objective lens further includes an aperture stop, which is located between two adjacent lenses in the middle group.

[0008] The beneficial effects of the embodiments of the first aspect of the present invention are as follows: the present invention provides a visible-ultraviolet dual-wavelength microscope objective lens, wherein the first lens group serves as a tube lens in the microscope objective lens, provides an initial focal length and imaging space for subsequent lens groups, converges light with its positive optical power and assists in aberration correction; the second lens group serves as an objective lens in the microscope objective lens, wherein the front group utilizes its negative optical power to balance field curvature and assist in chromatic aberration correction; the middle group utilizes its positive optical power to correct chromatic aberration, spherical aberration, coma, astigmatism, field curvature and higher-order aberrations; the rear group utilizes its positive optical power to correct field curvature, ensuring high resolution and wide field of view imaging; the microscope objective lens of the present invention effectively reduces the influence of chromatic aberration under a wide spectrum light source through the reasonable combination of positive and negative optical powers, maintains a high numerical aperture and a wide field of view characteristics, and can adapt to a wide spectrum of ultraviolet laser wavelengths.

[0009] As some sub-solutions of the above technical solution, the first lens group includes a first lens with positive refractive power, a second lens with positive refractive power, and a third lens with negative refractive power, which are arranged in sequence from the object plane to the image plane along the optical axis direction;

[0010] The front group includes a fourth lens with positive refractive power, a fifth lens with negative refractive power, a sixth lens with negative refractive power, and a seventh lens with positive refractive power, which are arranged in sequence from the object plane to the image plane along the optical axis.

[0011] The middle group includes an eighth lens having positive refractive power, a ninth lens having negative refractive power, a tenth lens having positive refractive power, an eleventh lens having negative refractive power, a twelfth lens having positive refractive power, a thirteenth lens having positive refractive power, a fourteenth lens having negative refractive power, and a fifteenth lens having positive refractive power, arranged in sequence from the object plane to the image plane along the optical axis.

[0012] The rear group includes a sixteenth lens having positive refractive power, a seventeenth lens having positive refractive power, an eighteenth lens having positive refractive power, and a nineteenth lens having positive refractive power, which are arranged in sequence from the object plane to the image plane along the optical axis.

[0013] The aperture stop is located between the twelfth lens and the thirteenth lens.

[0014] As some sub-solutions of the above technical solution, the first lens, the second lens, the seventh lens, the eighth lens, the tenth lens, the twelfth lens, the thirteenth lens, the fifteenth lens, and the sixteenth lens are all biconvex lenses; the third lens, the fifth lens, the sixth lens, the ninth lens, the eleventh lens, and the fourteenth lens are all biconcave lenses;

[0015] The fourth lens, the seventeenth lens, the eighteenth lens, and the nineteenth lens are all meniscus lenses curved toward the image plane.

[0016] As some sub-solutions of the above technical solution, the fifth lens, the sixth lens, the ninth lens and the fourteenth lens are aspherical lenses, each of the aspherical lenses includes an even-order aspherical surface and a spherical surface, and the even-order aspherical surfaces are respectively located on the object-side surface of the fifth lens, the object-side surface of the sixth lens, the image-side surface of the ninth lens, and the image-side surface of the fourteenth lens.

[0017] As some sub-solutions of the above technical solution, the third lens, the fifth lens, the sixth lens, the ninth lens, the eleventh lens, and the fourteenth lens are all made of fused silica; and the first lens, the second lens, the fourth lens, the seventh lens, the eighth lens, the tenth lens, the twelfth lens, the thirteenth lens, the fifteenth lens, the sixteenth lens, the seventeenth lens, the eighteenth lens, and the nineteenth lens are all made of calcium fluoride glass.

[0018] As some sub-solutions of the above technical solution, the object side field of view radius of the microscope objective lens is 20.5 mm, and the image side field of view radius is 0.41 mm.

[0019] As some sub-solutions of the above technical solution, the image side working distance of the microscope objective lens is ≥2 mm, and the tube lens working distance is ≥120 mm.

[0020] As some sub-solutions of the above technical solution, the image side numerical aperture of the microscope objective lens is 0.80, and the maximum relative distortion is 0.0244%; the object side of the microscope objective lens is a telecentric object space, and the image side telecentricity is less than 3.5 mrad.

[0021] As some sub-solutions of the above technical solution, the microscopic imaging wavelength of the microscope objective is 266±0.1nm, the autofocus wavelength is 403.8±0.1nm, and the object-image conjugate distance is 400mm; the combined focal length of the first lens group is 200mm, and the combined focal length of the second lens group is 4mm. The first lens group and the second lens group cooperate to enable the microscope objective to achieve a magnification of 1 / 50.

[0022] A second embodiment of the present invention provides an optical system comprising any one of the visible-ultraviolet dual-wavelength microscope objective lenses described above.

[0023] The optical system according to the embodiment of the second aspect of the present invention also has corresponding beneficial effects because it includes the visible-ultraviolet dual-wavelength microscope objective lens of the above technical solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0025] Figure 1 A schematic structural diagram of a visible-ultraviolet dual-wavelength microscope objective lens provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the optical path of a visible-ultraviolet dual-wavelength microscope objective lens provided in an embodiment of the present invention;

[0027] Figure 3 is the wavefront diagram of the central field of view of the microscope objective lens at a wavelength of 266.0nm;

[0028] Figure 4 This is the wavefront diagram of the edge field of view of the microscope objective lens at a wavelength of 266.0nm;

[0029] Figure 5 It is the wavefront diagram of the central field of view of the microscope objective lens at a wavelength of 403.8nm;

[0030] Figure 6 This is the wavefront diagram of the edge field of view of the microscope objective lens at a wavelength of 403.8nm;

[0031] Figure 7 This is the polychromatic modulation transfer function diagram of the microscope objective lens at a wavelength of 266.0nm;

[0032] Figure 8 This is the polychromatic modulation transfer function diagram of the microscope objective lens at a wavelength of 403.8nm;

[0033] Figure 9 The field curvature and distortion diagram of the microscope objective lens at a wavelength of 266.0nm;

[0034] Figure 10 This is the spot diagram of the microscope objective light at a wavelength of 266.0 nm;

[0035] Figure 11 This is the object space telecentricity error diagram of the microscope objective at a wavelength of 266.0nm.

[0036] In the accompanying drawings: L1-first lens; L2-second lens; L3-third lens; L4-fourth lens; L5-fifth lens; L6-sixth lens; L7-seventh lens; L8-eighth lens; L9-ninth lens; L10-tenth lens; L11-eleventh lens; L12-twelfth lens; L13-thirteenth lens; L14-fourteenth lens; L15-fifteenth lens; L16-sixteenth lens; L17-seventeenth lens; L18-eighteenth lens; L19-nineteenth lens. DETAILED DESCRIPTION

[0037] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0038] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0039] In the description of the present invention, "several" means an indefinite quantity, "multiple" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" is solely for the purpose of distinguishing technical features and should not be understood to indicate or imply relative importance, or to implicitly indicate the number or order of the technical features indicated. "And / or" throughout the text represents three parallel solutions. For example, "A and / or B" means a solution where A satisfies, a solution where B satisfies, or a solution where both A and B satisfy.

[0040] In the description of the present invention, if there is a short sentence containing multiple parallel features, the attributive defines the closest feature. For example, "B, C, and E are arranged on A, and are connected to D" means that B is arranged on A and E is connected to D, and does not constitute a limitation on C. However, attributives that express the relationship between features, such as "spaced arrangement" or "circular arrangement", do not fall into this category. If the word "all" is preceded by an attributive, it means that all features in the short sentence are limited. For example, "B, C, and D are all arranged on A" means that B, C, and D are all arranged on A. In a sentence with an omitted subject, the omitted subject is the subject of the previous sentence, that is, "B is arranged on A, including C" means that B is arranged on A and A includes C.

[0041] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0042] The following combination Figures 1 to 11 Embodiments of the present invention are described.

[0043] Reference Figure 1 and Figure 2According to a first aspect of the present invention, there is provided a visible-ultraviolet dual-wavelength microscope objective lens, comprising a first lens group with positive optical power and a second lens group with negative optical power, which are sequentially arranged along the optical axis of the microscope objective lens from the object plane to the image plane.

[0044] The second lens group includes a front lens group having negative optical power, a middle lens group having positive optical power, and a rear lens group having positive optical power;

[0045] The microscope objective lens further includes an aperture stop, which is located between two adjacent lenses in the middle group.

[0046] The microscope objective uses the image sensor's photosensitive surface as the virtual object plane above and the sample surface as the real image plane below. Utilizing the principle of reversible optical paths, light is transferred from the image sensor downward to the sample surface. The microscope objective consists of two lens groups. The first lens group has a positive focal length of 200mm and serves as the tube lens in the microscope objective, providing the initial focal length and imaging space for subsequent lens groups. Its positive focal length focuses light and corrects aberrations. The second lens group has a negative focal length of 4mm and serves as the objective lens in the microscope optical system. The first and second lens groups work together to achieve a magnification of 1 / 50. The second lens group is further subdivided into front, middle, and rear groups, each with a different optical role. The front group uses its negative focal length to balance field curvature and assist in chromatic aberration correction. The middle group has a complex structure and is responsible for correcting various primary and higher-order aberrations, including chromatic aberration, spherical aberration, coma, astigmatism, and field curvature. The rear group is primarily responsible for further field curvature correction to ensure high resolution and large field of view imaging.

[0047] In view of the differences in optical properties between visible light and deep ultraviolet bands, especially the lack of available optical glue and high-transmittance materials in the deep ultraviolet band, the projection objective lens of the first embodiment of the present invention adopts fused quartz and calcium fluoride, two materials with high transmittance in the deep ultraviolet band. These two materials show excellent transmittance in the deep ultraviolet band, and the internal transmittance exceeds 99% at the working wavelength, which effectively eliminates chromatic aberration and ensures the high transmittance of the system.

[0048] The microscope objective utilizes optical glass with different Abbe numbers and a rational combination of positive and negative optical powers to effectively reduce the effects of chromatic aberration under broad-spectrum light sources, improve system image quality, and achieve finer resolution and superior imaging quality. The microscope objective is set to an operating wavelength of 266nm with a linewidth of ±0.1nm, which meets the adaptability range of ultraviolet laser wavelengths. The microscope objective also adapts to a wavelength of 403.8nm with a linewidth of ±0.1nm, which meets the requirements for use with autofocus lasers. This makes the microscope objective suitable for microscopic inspection in the visible-ultraviolet band and is also suitable for fields such as printing platemaking and photolithography objectives.

[0049] Specifically, the first lens group includes a first lens L1 with positive refractive power, a second lens L2 with positive refractive power, and a third lens L3 with negative refractive power, which are arranged in sequence from the object plane to the image plane along the optical axis.

[0050] The front group includes, arranged in order from its object plane to its image plane along its optical axis, a fourth lens L4 with positive refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with negative refractive power, and a seventh lens L7 with positive refractive power;

[0051] The middle group includes, arranged in order from the object plane to the image plane along the optical axis, an eighth lens L8 with positive refractive power, a ninth lens L9 with negative refractive power, a tenth lens L10 with positive refractive power, an eleventh lens L11 with negative refractive power, a twelfth lens L12 with positive refractive power, a thirteenth lens L13 with positive refractive power, a fourteenth lens L14 with negative refractive power, and a fifteenth lens L15 with positive refractive power;

[0052] The rear group includes a sixteenth lens L16 having positive refractive power, a seventeenth lens L17 having positive refractive power, an eighteenth lens L18 having positive refractive power, and a nineteenth lens L19 having positive refractive power, which are arranged in order from the object plane to the image plane along the optical axis.

[0053] The aperture stop is located between the twelfth lens L12 and the thirteenth lens L13.

[0054] In the first lens group, both the first lens L1 and the second lens L2 have positive refractive power. They work together to initially converge the light from the object plane, laying the foundation for the subsequent imaging process. The third lens L3 has negative refractive power and is used to adjust the degree of light convergence to balance the positive refractive power of the first and second lenses, thereby optimizing the aberration correction effect of the entire system.

[0055] In the front group of the second lens group, the fourth lens L4 has positive focal power and cooperates with the subsequent lenses to continue converging light. The fifth lens L5 and the sixth lens L6 both have negative focal power and jointly undertake the task of correcting chromatic aberration and helping to balance field curvature. The seventh lens L7 has positive focal power, further converging light and assisting in correcting aberrations.

[0056] The middle group of the second lens group includes lenses with various optical powers to comprehensively correct various aberrations, including chromatic aberration, spherical aberration, coma, astigmatism, and field curvature. Among them, the eighth through fifteenth lenses, L8 and L15, achieve fine control of light through alternating positive and negative optical powers, ensuring the system's high resolution and large field of view imaging capabilities.

[0057] In the rear group of the second lens group, the sixteenth to nineteenth lenses, L16 to L19, all have positive refractive power. They work together to converge light and perform the final field curvature correction task, ensuring a flat and sharp image.

[0058] The aperture stop is located between the twelfth lens L12 and the thirteenth lens L13. Its function is to limit the bundle of light passing through the system, thereby controlling the depth of field and image clarity, and also helps to reduce aberrations.

[0059] The microscope objective achieves precise control of light and high-quality aberration correction through carefully designed lens combinations and aperture diaphragm positions, thus ensuring excellent imaging performance of the system under high resolution and large field of view conditions.

[0060] Specifically, the first lens L1, the second lens L2, the seventh lens L7, the eighth lens L8, the tenth lens L10, the twelfth lens L12, the thirteenth lens L13, the fifteenth lens L15 and the sixteenth lens L16 are all biconvex lenses;

[0061] The third lens L3, the fifth lens L5, the sixth lens L6, the ninth lens L9, the eleventh lens L11 and the fourteenth lens L14 are all biconcave lenses;

[0062] The fourth lens L4, the seventeenth lens L17, the eighteenth lens L18 and the nineteenth lens L19 are all meniscus lenses curved toward the image plane.

[0063] The meniscus lens has a convex side and a concave side. Its design, which is curved toward the image plane, enables it to provide a smaller positive optical focal length. The meniscus lens is mainly used to correct field curvature in projection objectives. Its special shape and optical focal length distribution help to balance the imaging performance of the system.

[0064] The biconvex lens has convex surfaces on both sides, which can provide large positive optical power and enhance the focusing ability of the system. The biconvex lens is mainly used in projection objective lenses to enhance the focusing effect of light, and at the same time participates in the correction of aberrations such as chromatic aberration and spherical aberration.

[0065] Biconcave lenses, with concave surfaces on both sides, provide a large negative optical power that helps balance the positive optical power produced by other lenses in the system, thereby achieving further correction of aberrations.

[0066] Specifically, the fifth lens L5, the sixth lens L6, the ninth lens L9 and the fourteenth lens L14 are aspheric lenses, each of which includes an even-order aspheric surface and a spherical surface. The even-order aspheric surfaces are respectively located on the object-side surface of the fifth lens L5, the object-side surface of the sixth lens L6, the image-side surface of the ninth lens L9, and the image-side surface of the fourteenth lens L14.

[0067] Compared with traditional spherical lenses, aspheric lenses can better correct aberrations, including spherical aberration, coma, astigmatism, etc., thereby improving image clarity; even aspheric surfaces have higher degrees of freedom and can accurately correct specific aberrations, further improving image quality.

[0068] The four even-order aspheric surfaces in the projection objective can be further refined into:

[0069] The object side of the fifth lens L5 corrects the aberrations generated when light emitted from the projection object enters the lens, ensuring that the light can be accurately captured by the lens and transmitted to the subsequent lens;

[0070] The object side of the sixth lens element L6 further corrects aberrations caused by light propagation through the lens and helps adjust the convergence angle of light to ensure that light is accurately projected onto the screen.

[0071] Image side of the ninth lens L9: Before the light leaves the lens and is projected onto the screen, it performs final correction and adjustment on the light to ensure the clarity and accuracy of the projected image.

[0072] The image side surface of the fourteenth lens L14: optimizes the edge quality of the projected image and ensures the uniformity and consistency of the entire projected image.

[0073] In the microscope objective, all lenses except the fifth lens L5, the sixth lens L6, the ninth lens L9 and the fourteenth lens L14 have spherical structures.

[0074] Specifically, the third lens L3, the fifth lens L5, the sixth lens L6, the ninth lens L9, the eleventh lens L11, and the fourteenth lens L14 are all made of fused silica; the first lens L1, the second lens L2, the fourth lens L4, the seventh lens L7, the eighth lens L8, the tenth lens L10, the twelfth lens L12, the thirteenth lens L13, the fifteenth lens L15, the sixteenth lens L16, the seventeenth lens L17, the eighteenth lens L18, and the nineteenth lens L19 are all made of calcium fluoride glass.

[0075] Fused quartz, a material with high transmittance, low thermal expansion coefficient, and low dispersion, is particularly suitable for optical design in the deep ultraviolet and visible light bands. Lenses made of fused quartz help reduce chromatic aberration and improve imaging quality. Calcium fluoride glass, with its excellent transmittance and low dispersion in the UV band, is an ideal choice for deep ultraviolet optical design. Lenses made of calcium fluoride glass help ensure system imaging performance in the deep ultraviolet band. The fused quartz and calcium fluoride glass materials used in projection objectives have internal transmittances exceeding 99% at 248.6nm and 546nm, respectively.

[0076] Specifically, the object-side field of view radius of the microscope objective lens is 20.5 mm, and the image-side field of view radius is 0.41 mm.

[0077] The object side field of view radius is 20.5mm, and the image side field of view radius is 0.41mm, indicating that the magnification of the microscope objective lens meets the usage requirements.

[0078] Specifically, the image side working distance of the microscope objective is ≥2 mm, and the tube lens working distance is ≥120 mm.

[0079] The image-side working distance is ≥2mm, which means that the distance between the imaging surface of the microscope objective (such as the detector or film) and the last lens surface is at least 2mm, which ensures sufficient space to install the detector without interfering with the imaging; the tube lens working distance is ≥120mm, and the connection distance between the microscope objective and the eyepiece or camera adapter is sufficient, ensuring that the microscope objective can be flexibly connected to various observation or imaging equipment.

[0080] Specifically, the image side numerical aperture of the microscope objective lens is 0.80, and the maximum relative distortion is 0.0244%; the object side of the microscope objective lens is a telecentric object space, and the image side telecentricity is less than 3.5 mrad.

[0081] High numerical aperture and low distortion enable the projection objective to meet the requirements of high-power laser passage; the reverse optical path design may help reduce aberrations, thereby improving resolution; low telecentricity means that the imaging is more stable and is not affected by slight changes in the position of the object or detector.

[0082] Specifically, the microscopic imaging wavelength of the microscope objective is 266±0.1 nm, the autofocus wavelength is 403.8±0.1 nm, and the object-image conjugate distance is 400 mm; the combined focal length of the first lens group is 200 mm, and the combined focal length of the second lens group is 4 mm. The first lens group and the second lens group cooperate to enable the microscope objective to achieve a magnification of 1 / 50.

[0083] The wavelength of microscopic imaging is 266±0.1nm, which is suitable for high-resolution imaging or detection of specific materials. Due to its shorter wavelength, ultraviolet light can provide finer resolution, allowing the microscope objective to observe smaller details; the autofocus wavelength is 403.8±0.1nm, which is used for autofocus. Autofocus is a very important function in microscopic imaging. It can ensure that the microscope objective can accurately align with the object, thereby improving the accuracy and stability of imaging; the first lens group serves as a tube lens, and its combined focal length is longer, which helps to provide sufficient imaging space and focal length for the subsequent objective lens part. The second lens group serves as an objective lens, and its combined focal length is shorter, which helps to achieve higher magnification and resolution; in the system, the object-image conjugate distance is set to 400mm.

[0084] The various optical components of the projection objective lens provided in the embodiment of the first aspect of the present invention meet the conditions of Tables 1, 2 and 3; Table 1 is the constraint parameters of the projection objective lens; Table 2 is the design parameters of the projection objective lens; Table 3 is the surface coefficients of the aspheric lens.

[0085] Table 1

[0086]

[0087]

[0088] Table 2

[0089]

[0090]

[0091] It should be noted that the image distance in Table 2 is the data when the microscope objective lens has a central wavelength of 266.0 nm. When the central wavelength is 403.8 nm, the object distance is 2.229 mm.

[0092] Table 3

[0093] Face number 4th-order term 6th-order term 8th-order term 10th-order term 9 2.354E-004 -5.103E-006 -6.727E-009 4.863E-009 11 2.980E-005 3.572E-006 9.347E-009 1.708E-009 18 1.569E-005 -1.209E-009 -4.624E-011 -5.017E-013 29 2.286E-006 -3.536E-008 -9.632E-011 -5.166E-014

[0094] Under the conditions of working wavelength range, object field radius, image numerical aperture and other parameters in Table 1, according to the analysis and calculation of professional optical design software Opticstudio, the aberration correction degree of the microscope objective lens is as follows:

[0095] Reference Figure 3 and Figure 4 , Figure 3 、 Figure 4 They are the wavefront diagrams at the central wavelength λ = 266.0nm of the microscope objective optical system, the RMS wavefront value of the central field of view is 0.0320λ, and the RMS wavefront value of the edge field of view is 0.0251λ; Figure 5 and Figure 6 , Figure 5 、 Figure 6 : is the wavefront diagram of the projection objective optical system of this embodiment at the central wavelength λ=403.8nm, the RMS wavefront value of the central field of view is 0.0522λ, and the RMS wavefront value of the edge field of view is 0.0838λ; Figures 3 to 6 This shows that the wavefront aberration of the microscope objective is well corrected, the imaging quality is close to perfect imaging, and the chromatic aberration between wavelengths is well corrected.

[0096] Reference Figure 7 and Figure 8 , Figure 7 and Figure 8The polychromatic modulation transfer function (MTF) of the microscope objective at 266.0nm and 403.8nm is shown, respectively, approaching the diffraction limit. The MTF with 266.0nm as the central operating wavelength is greater than 0.31 at 3000 lp / mm, and the MTF with 403.8nm as the central operating wavelength is greater than 0.36 at 1800 lp / mm, fully meeting imaging requirements.

[0097] Reference Figure 9 , Figure 9 This is a diagram of the field curvature and distortion of the microscope objective. At the central wavelength of 266.0 nm, the field curvature is less than 0.4 μm, and the maximum relative distortion is 0.0242%, corresponding to a distortion of 87.51 nm. The field curvature and distortion have been well corrected.

[0098] Reference Figure 10 , Figure 10 This is the point diagram of the microscope objective lens with a central operating wavelength of 266.0 nm. The maximum RMS radius is 0.166 μm, which is better than the Airy radius of 201 μm and close to perfect imaging.

[0099] Reference Figure 11 , Figure 11 It is the object space telecentricity error of the microscope objective lens when the operating wavelength is centered at 266.0nm. The maximum value is 3.5mrad, and the image space telecentricity has been well corrected.

[0100] From the above, it can be seen that the visible-ultraviolet dual-wavelength microscope objective lens provided by the embodiment of the first aspect of the present invention has excellent imaging quality, achieves a magnification of 1 / 50, maintains a high numerical aperture and a large field of view, can adapt to deep ultraviolet wavelengths and simultaneously meet the dual-wavelength requirements required for observation and autofocus.

[0101] An optical system in an embodiment of the second aspect of the present invention includes the visible-ultraviolet dual-wavelength microscope objective lens of the above embodiment.

[0102] The optical system according to the embodiment of the second aspect of the present invention also has corresponding beneficial effects because it includes the visible-ultraviolet dual-wavelength microscope objective lens of the above technical solution.

[0103] The above specifically describes the preferred embodiments of the present invention, but the present disclosure is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present disclosure.

Claims

1. A visible-ultraviolet dual-wavelength microscope objective lens, characterized in that: The microscope comprises a first lens group with positive optical power and a second lens group with positive optical power, which are sequentially arranged from the object plane to the image plane along the optical axis direction of the microscope objective lens; The first lens group comprises a first lens (L1) with positive focal power, a second lens (L2) with positive focal power, and a third lens (L3) with negative focal power, which are sequentially arranged along the optical axis of the microscope objective lens from the object plane to the image plane; The second lens group includes a front lens group having negative optical power, a middle lens group having positive optical power, and a rear lens group having positive optical power; The front group comprises a fourth lens (L4) with negative optical power, a fifth lens (L5) with negative optical power, a sixth lens (L6) with negative optical power, and a seventh lens (L7) with positive optical power, which are arranged in sequence from the object plane of the microscope objective lens to the image plane along the optical axis of the microscope objective lens; The middle group includes an eighth lens (L8) with positive focal power, a ninth lens (L9) with negative focal power, a tenth lens (L10) with positive focal power, an eleventh lens (L11) with negative focal power, a twelfth lens (L12) with positive focal power, a thirteenth lens (L13) with positive focal power, a fourteenth lens (L14) with negative focal power, and a fifteenth lens (L15) with positive focal power, which are arranged in sequence from the object plane to the image plane along the optical axis of the microscope objective lens; The rear group includes a sixteenth lens (L16) with positive refractive power, a seventeenth lens (L17) with positive refractive power, an eighteenth lens (L18) with positive refractive power, and a nineteenth lens (L19) with positive refractive power, which are sequentially arranged along the optical axis of the microscope objective lens from the object plane to the image plane; The microscope objective lens further includes an aperture stop, wherein the aperture stop is located between the twelfth lens (L12) and the thirteenth lens (L13); The number of lenses with optical power in the microscope objective lens is 19; the design parameters of the microscope objective lens are as follows:

2. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 1, characterized in that: The object side field of view radius of the microscope objective lens is 20.5 mm, and the image side field of view radius is 0.41 mm.

3. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 1, characterized in that: The image-side numerical aperture of the microscope objective lens is 0.80, and the maximum relative distortion is 0.0244%; the object side of the microscope objective lens is a telecentric object space, and the image-side telecentricity is less than 3.5 mrad.

4. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 1, characterized in that: The microscope objective lens has a microscopic imaging wavelength of 266±0.1 nm and an autofocus wavelength of 403.8±0.1 nm.

5. An optical system, characterized in that: The invention comprises the visible-ultraviolet dual-wavelength microscope objective lens according to any one of claims 1 to 4.

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