Visible-ultraviolet dual-wavelength microscope objective and optical system

Abstract

The invention relates to the technical field of optical instruments, and discloses a visible-ultraviolet dual-wavelength microscope objective and an optical system.The visible-ultraviolet dual-wavelength microscope objective comprises a first lens set with positive focal power and a second lens set with negative focal power which are sequentially arranged from the object plane to the image plane of the microscope objective in the optical axis direction of the microscope objective; the second lens group comprises a front group with negative focal power, a middle group with positive focal power and a rear group with positive focal power; the microscope objective also comprises an aperture diaphragm; the aperture diaphragm is positioned between the two adjacent lenses in the middle group; according to the microscope objective, through reasonable matching of the positive focal power and the negative focal power, the influence of chromatic aberration under a wide-spectrum light source is effectively reduced, the high numerical aperture and the large view field characteristic are kept, and the microscope objective can adapt to the wide-spectrum ultraviolet laser wavelength.

Description

Technical Field

[0001] The 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 shown significant advantages in the field of target detection and identification, and have promoted the rapid development of ultraviolet optical technology. With the increasing requirements for detection accuracy in defense engineering, industrial detection, space science and other fields, microscope systems have gradually expanded to the ultraviolet band to improve resolution and contrast. The resolution of diffraction-limited features gradually increases with the decrease in wavelength and the increase in numerical aperture (NA), allowing the ultraviolet band to achieve resolution that exceeds that of visible light systems. At the same time, in order to meet the needs of full-surface wafer scanning time and improve the throughput efficiency of automatic optical inspection equipment, microscope objectives need to have ultraviolet working bands, high numerical apertures, and large field of view characteristics.

[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 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 direction from the object plane to the image plane of the microscope objective lens;

[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 comprises an aperture stop, wherein the aperture stop 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 focal length and assists in aberration correction; the second lens group serves as an objective lens in the microscope objective lens, wherein the front lens group utilizes its negative optical focal length to balance field curvature and assists in chromatic aberration correction; the middle lens group utilizes its positive optical focal length to correct chromatic aberration, spherical aberration, coma, astigmatism, field curvature and higher-order aberrations; the rear lens group utilizes its positive optical focal length to perform field curvature correction to ensure high-resolution and large-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 a reasonable combination of positive and negative optical focal lengths, maintains a relatively high numerical aperture and a large-field-of-view characteristic, and can adapt to a wide-spectrum ultraviolet laser wavelength.

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

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

[0011] The middle group includes an eighth lens with positive focal power, a ninth lens with negative focal power, a tenth lens with positive focal power, an eleventh lens with negative focal power, a twelfth lens with positive focal power, a thirteenth lens with positive focal power, a fourteenth lens with negative focal power and a fifteenth lens with positive focal power, which are sequentially arranged along the optical axis direction from the object plane to the image plane;

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

[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-schemes of the above technical scheme, the fifth lens, the sixth lens, the ninth lens and the fourteenth lens are aspherical lenses, and 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; 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 ≥2mm, and the tube lens working distance is ≥120mm.

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

[0021] As some sub-schemes of the above technical scheme, 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 aspect 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 easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0025] Figure 1 A schematic diagram of the structure 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 provided by an embodiment of the present invention;

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

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

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

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

[0031] Figure 7 It is the graph of the complex color modulation transfer function of the microscope objective lens at a wavelength of 266.0nm;

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

[0033] Fig. 9 It is the field curvature and distortion diagram of the microscope objective lens at a wavelength of 266.0nm;

[0034] Fig.10 It is the spot diagram of microscope objective light at a wavelength of 266.0nm;

[0035] Fig.11 This is the object 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] Embodiments of the present invention are described in detail below, examples of which 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 only used to explain the present invention, and cannot be understood 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., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and 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, and therefore should not be understood as a limitation on the present invention.

[0039] In the description of the present invention, the meaning of "several" is an indefinite quantity, the meaning of "multiple" is more than two, "greater than", "less than", "exceed", etc. are understood as not including the number itself, and "above", "below", "within", etc. are understood as including the number itself. If there is a description of the first and the second, it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features. The "and / or" that appears in the full text represents three parallel solutions. For example, A and / or B represents the solution satisfied by A, the solution satisfied by B, or the solution satisfied by both A and B.

[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 connected to D are arranged on A, which means that B is arranged on A and E is connected to D, and does not constitute a limitation on C; but attributives that indicate the relationship between features, such as "interval arrangement" or "circular arrangement", do not belong to this category. If the word "all" is preceded by an attributive, it means that all features in the short sentence are limited, such as B, C, and D are all arranged on A, which means that B, C, and D are all arranged on A. For 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, which 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, connecting, etc. 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 in combination with the specific content of the technical solution.

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

[0043] Reference Figure 1 and Figure 2, a first aspect of the present invention provides a visible-ultraviolet dual-wavelength microscope objective lens, comprising a first lens group with positive focal length and a second lens group with negative focal length, which are sequentially arranged along the optical axis direction from the object plane to the image plane of the microscope objective lens;

[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 comprises an aperture stop, wherein the aperture stop is located between two adjacent lenses in the middle group.

[0046] The microscope objective uses the photosensitive surface of the image sensor as a virtual object plane and the surface of the sample to be measured as a real image plane. The light path is transmitted from the image sensor downward to the sample surface by using the reversible principle of the optical path. The microscope objective consists of two lens groups. The first lens group has a positive focal length of 200mm. As the tube lens in the microscope objective, the first lens group provides the initial focal length and imaging space for the subsequent lens groups, converges light with its positive focal length and is responsible for aberration correction. The second lens group has a negative focal length of 4mm and is the objective lens part of the microscope optical system. The first lens group and the second lens group work together to achieve a magnification of 1 / 50. The second lens group is further subdivided into the front, middle and rear groups, each of which plays a different optical role: the front group uses its negative focal length to balance the field curvature and assist in chromatic aberration correction; the middle group has a complex structure and is responsible for correcting a variety of primary and advanced aberrations including chromatic aberration, spherical aberration, coma, astigmatism, field curvature, etc.; the rear group is mainly 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 of the embodiment of the first aspect 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 lens uses optical glass with different Abbe numbers and a reasonable combination of positive and negative optical powers to effectively reduce the influence of chromatic aberration under wide-spectrum light sources, improve the system image quality, and achieve finer resolution and excellent imaging quality. The working wavelength of the microscope objective lens is set to 266nm, and the line width is ±0.1nm, which meets the adaptability range of ultraviolet laser wavelengths; the microscope objective lens is also adapted to a wavelength of 403.8nm, and the line width is ±0.1nm, which meets the use of autofocus lasers; so that the microscope objective lens can be used for microscopic detection in the visible-ultraviolet band, and is also suitable for printing plate making lithography objectives and other fields.

[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 sequentially arranged along the optical axis direction from the object plane to the image plane;

[0050] The front group includes 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, which are arranged in sequence from the object plane to the image plane along the optical axis direction;

[0051] The middle group includes 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, which are arranged in sequence from the object plane to the image plane along the optical axis direction;

[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 sequence from the object plane to the image plane along the optical axis direction;

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

[0054] In the first lens group, the first lens L1 and the second lens L2 both have positive refractive power, and 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 its function is to adjust the convergence degree of light to balance the positive refractive power generated by 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 power, and cooperates with the subsequent lenses to continue to converge light; the fifth lens L5 and the sixth lens L6 both have negative power, and they jointly undertake the task of chromatic aberration correction and help balance field curvature; the seventh lens L7 has positive power, further converges light, and assists in correcting aberrations;

[0056] The middle group of the second lens group includes lenses with various optical powers, which are designed to fully correct various aberrations, including chromatic aberration, spherical aberration, coma, astigmatism and field curvature. Among them, the eighth lens L8 to the fifteenth lens L15 achieve fine control of light through the alternating arrangement of 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 lens L16 to the nineteenth lens L19 are all of positive refractive power. They work together to converge light and undertake the final field curvature correction task to ensure the flatness and clarity of the image plane;

[0058] The aperture stop is located between the twelfth lens L12 and the thirteenth lens L13. Its function is to limit the light beam 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 the carefully designed lens combination and the position of the aperture diaphragm, thus ensuring the 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 of bending 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 balance the imaging performance of the system.

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

[0065] Biconcave lenses are concave on both sides, providing 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 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 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-order 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 as follows:

[0069] The object side of the fifth lens L5: corrects the aberration generated when the 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 L6: further corrects the aberration generated during the propagation of light in the lens, and helps adjust the convergence angle of light to ensure that the light can be 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 makes the final correction and adjustment 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 are 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 is a material with high light transmittance, low expansion coefficient and low dispersion, which is particularly suitable for optical design in the deep ultraviolet and visible light bands; the lens is made of fused quartz material, which helps to reduce chromatic aberration and improve imaging quality; calcium fluoride glass has excellent light transmittance and low dispersion characteristics in the ultraviolet band, which is an ideal choice for deep ultraviolet optical design; the lens is made of calcium fluoride glass material, which helps to ensure the imaging performance of the system in the deep ultraviolet band. The internal transmittance of the fused quartz glass material and calcium fluoride glass material used in the projection objective lens exceeds 99% at 248.6nm and 546nm.

[0076] Specifically, the object-side field of view radius of the microscope objective 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 surface of the last lens 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 is 0.80, and the maximum relative distortion is 0.0244%; the object side of the microscope objective 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 and thus improve 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±0.1nm, 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.

[0083] The wavelength of microscopic imaging is 266±0.1nm, which is suitable for high-resolution imaging or detection of specific materials. Ultraviolet light can provide finer resolution due to its shorter wavelength, 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 provided in the embodiment of the first aspect of the present invention meet the conditions of Table 1, Table 2 and Table 3; Table 1 is the constraint parameters of the projection objective; Table 2 is the design parameters of the projection objective; 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 working wavelength range, object field radius, image numerical aperture and other parameter conditions in Table 1, according to the analysis and calculation of professional optical design software Opticstudio, the aberration correction degree of the microscope objective 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 a wavefront diagram of the projection objective optical system of this embodiment at a 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 It 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, which is close to the diffraction limit. Among them, the MTF with 266.0nm as the central working wavelength is greater than 0.31 at 3000lp / mm, and the MTF with 403.8nm as the central working wavelength is greater than 0.36 at 1800lp / mm, which fully meets the imaging requirements.

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

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

[0099] Reference Fig.11 , Fig.11 It is the object telecentricity error of the microscope objective lens with a central working wavelength of 266.0nm, of which the maximum value is 3.5mrad, and the image telecentricity has been well corrected.

[0100] From the above, it can be seen that the visible-ultraviolet dual-wavelength microscope objective 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 preferred embodiments of the present invention are described in detail above, 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: It comprises a first lens group with positive optical power and a second lens group with negative optical power which are arranged in sequence from the object plane to the image plane of the microscope objective lens along the optical axis direction thereof; 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 microscope objective lens further comprises an aperture stop, wherein the aperture stop is located between two adjacent lenses in the middle group.

2. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 1, characterized in that: The first lens group comprises 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 direction; The front group includes a fourth lens (L4) with positive focal power, a fifth lens (L5) with negative focal power, a sixth lens (L6) with negative focal power and a seventh lens (L7) with positive focal power, which are sequentially arranged along the optical axis direction from the object plane to the image plane; 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 direction; The rear group includes a sixteenth lens (L16) with positive focal power, a seventeenth lens (L17) with positive focal power, an eighteenth lens (L18) with positive focal power and a nineteenth lens (L19) with positive focal power, which are arranged in sequence from the object plane to the image plane along the optical axis direction; the aperture stop is located between the twelfth lens (L12) and the thirteenth lens (L13).

3. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 2, characterized in that: 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; 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; 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.

4. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 2, characterized in that: The fifth lens (L5), the sixth lens (L6), the ninth lens (L9) and the fourteenth lens (L14) are aspherical lenses, each of which comprises an even-order aspherical surface and a spherical surface, and the even-order aspherical surface is 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).

5. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 2, characterized in that: 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.

6. 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.

7. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 1, characterized in that: The image side working distance of the microscope objective lens is ≥2mm, and the tube lens working distance is ≥120mm.

8. 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.

9. The visible-ultraviolet dual-wavelength microscope objective lens according to claim 1, characterized in that: 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.

10. An optical system, characterized in that: The invention comprises the visible-ultraviolet dual-wavelength microscope objective lens as described in any one of claims 1 to 9.

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